Tooth Shade and Ambient Illuminance Interact to Affect the Trueness and Repeatability of Intraoral Scanners: A Full-Factorial Experimental Study

Tooth Shade and Ambient Illuminance Interact to Affect the Trueness and Repeatability of Intraoral Scanners: A Full-Factorial Experimental Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Tooth Shade and Ambient Illuminance Interact to Affect the Trueness and Repeatability of Intraoral Scanners: A Full-Factorial Experimental Study EREN OZTURK, ORHUN OZTURK, AYSEGUL GULERYUZ This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9329206/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Background The present study was designed to investigate the influence of tooth shade and ambient illuminance on the trueness and repeatability of three intraoral scanners and to determine whether these factors interact under controlled experimental conditions. Methods A mandibular phantom model was scanned using three intraoral scanners: ITERO Element 5D, SIRONA CEREC AC Omnicam, and SHINING Aoralscan 3. Two tooth shades (A1 and A4) were evaluated under four ambient illuminance levels (100, 500, 1000, and 5000 lux). A full-factorial experimental design (three-way ANOVA) was employed, yielding 240 scans and 960 distance measurements. Reference values were obtained using a desktop scanner (MEDIT T500). Trueness was calculated as the mean deviation of landmark distances (Δmean, µm), with clinical acceptability defined as Δmean ≤ 120 µm. Effects were analyzed using a three-way ANOVA with post hoc comparisons. Results Of the factors tested, scanner type had the strongest effect on trueness (η²p = 0.237), consistent with a large effect by conventional benchmarks. A three-way interaction was also detected among scanner type, tooth shade, and ambient illuminance (η²p = 0.138), indicating that the influence of tooth shade on trueness varied across scanner–illuminance combinations. ITERO demonstrated a shade-dependent crossover pattern, with trueness decreasing under A1 and improving under A4 at higher illuminance. SIRONA CEREC AC Omnicam showed intermediate trueness with relative illuminance stability. SHINING Aoralscan 3 exhibited the lowest trueness, with acceptance rates as low as 10% under A1 at L1000, rendering this condition clinically unsuitable. Repeatability remained high across all scanners (CV% < 0.33%). Conclusions Scanner type was the primary determinant of trueness. Illuminance effects were device- and shade-dependent, and no single illuminance level was optimal. Clinically acceptable group means may mask clinically unacceptable individual measurements, underscoring the value of individual-level evaluation in accuracy assessments. Ambient illuminance Digital impression Intraoral scanner Repeatability Trueness Tooth shade Figures Figure 1 Figure 2 Figure 3 Introduction Intraoral scanning has evolved significantly in digital dentistry over the past three decades. The CEREC system, introduced in the 1980s, has seen significant advancements in hardware and software, resulting in increased compactness, accuracy, and user-friendliness [ 1 ]. Subsequent generations of intraoral scanners have broadened their clinical applications, progressing from single-unit restorations to full-arch digital impressions for a range of prosthodontic indications [ 2 ]. In prosthetic treatment, accurate transfer of tooth and soft-tissue anatomy is critical for the fabrication of clinically acceptable indirect restorations [ 3 ]. Intraoral scanners, which employ a range of optical imaging technologies, have become integral to contemporary clinical workflows and offer well-documented advantages over conventional impression techniques, including improved repeatability, reduced procedural errors, and greater patient comfort [ 4 , 5 ]. Realizing these benefits requires both high trueness — defined as the closeness of agreement between scan data and true geometry — and high repeatability, as defined by ISO 20896-1:2019 [ 6 ]. Both parameters are susceptible to a range of technical and environmental factors, including scanning protocol, calibration frequency, ambient illuminance, restorative material surface properties, and the presence of mobile soft tissues [ 6 ]. Recent studies have also explored how various factors influence intraoral scanner performance. Although prior studies have established that ambient illuminance influences intraoral scanning trueness and that tooth shade may modulate scanner performance under varying lighting conditions, no previous study has systematically examined their combined interaction within a single controlled design [ 7 ]. Furthermore, no study has applied controlled spectrophotometric shade standardization across all scanner–illuminance combinations using the same physical model. This methodological gap precludes direct isolation of shade as an independent variable. As a result, clinicians currently lack device- and shade-specific illuminance recommendations [ 8 ]. Given this limitation, the present study was designed to evaluate the individual and combined effects of scanner type, tooth shade, and ambient illuminance on trueness and repeatability across a full-factorial experimental design. Three intraoral scanners were assessed under two standardized tooth shades and four illuminance levels using a phantom model with controlled spectrophotometric shade verification. In addition to conventional group-mean analysis, individual-measurement-level clinical acceptance rates were computed to detect failure patterns that group-level statistics alone may obscure [ 9 , 10 , 11 ]. This approach goes beyond conventional group-mean reporting and provides clinicians with practical, device-specific, and shade-specific guidance for scanning protocols. While newer generations of intraoral scanners have been introduced, the present study does not aim to provide a device-specific comparison limited to particular commercial models. Instead, it focuses on fundamental relationships between scanner type, surface optical properties, and ambient illuminance. These underlying mechanisms are inherent to optical acquisition systems and are not restricted to a single device generation. Therefore, the findings of this study may provide insights that remain relevant beyond the specific scanners evaluated, contributing to a broader understanding of intraoral scanning performance under varying clinical conditions. The null hypothesis was that scanner type, tooth shade, and ambient illuminance each exerted independent effects on intraoral scanner trueness, with no statistically significant interactions among them. This expectation was informed by prior studies that examined these variables in isolation, providing limited evidence of strong interdependencies. Accordingly, each factor was anticipated to contribute independently to trueness variance, without meaningfully modulating the effect of the other variables. Materials and Methods Study Design, Acquisition of Reference Data, and Model Preparation An in vitro study design was used to allow strict control of optical and environmental variables, particularly illuminance and surface shade. A full-arch mandibular phantom jaw model (Fuji Phantom Typodont) was used, as in vivo conditions can introduce several uncontrollable factors. These include saliva, patient movement, soft tissue dynamics, and variations in reflective surfaces. Such factors can obscure the independent and combined effects of scanner optics, tooth shade, and ambient lighting on measurement trueness. Metal projections were created on the incisal tips of the canine teeth and the mesiobuccal cusps of the first molars on the mandibular phantom model to standardize the measurements. The phantom teeth were adjusted to A1 and A4 shades using the Vita Classical shade guide and the Spectro Shade device (Spectro Shade Micro, MHT S.p.A., Milan, Italy). High-precision reference data (gold standard) were obtained from the phantom model using the MEDIT T500 desktop laboratory scanner (Medit Inc., Seoul, Korea). This device is known for its high resolution and accuracy in dental applications [12]. Desktop laboratory scanners, such as the MEDIT T500, are commonly used as reference systems in digital dentistry studies due to their superior trueness and resolution compared to intraoral scanners. The scanner uses structured light with a blue LED, with reported accuracy of <7 µm and a depth resolution of 0.1 mm. All measurement data were recorded in STL format using CloudCompare software (version 2.14) [13]. Adjustment of Color Conditions for Scanning Data The phantom mandibular jaw model was initially in the A1 shade and scanned under this condition. The model's teeth were then recolored to A4 using the GC Optiglaze Color kit (GC Europe N.V.) according to the manufacturer’s protocol. Two successive layers were applied to all tooth surfaces with a brush applicator, and each layer was light-cured for 20 seconds using a dental curing unit. Shade accuracy was verified using the Spectro Shade device both before and after the recoloring procedure. Determination of Ambient and Light Conditions for Digital Scanning All scans were performed at a controlled room temperature of 24 °C, which is within the typical range for dental operatory conditions (22–26 °C) [14]. Maintaining a stable temperature helped reduce potential thermal changes in the phantom model. This also ensured that any differences in the measurements were mainly due to experimental factors, such as scanner type, tooth shade, and illuminance, rather than temperature fluctuations. A Govee GBWW Smart LED Bulb lighting system was used to control illuminance and color temperature. The phantom models were placed inside a sealed box with a matte-coated interior surface to provide uniform lighting conditions. During scanning, light levels were measured around the scanning head using a lux meter (Testo AG, Germany) and maintained constant throughout the scans. Illuminance levels were chosen to represent the range commonly encountered in clinical dental settings: 100 lux (L100), 500 lux (L500), 1000 lux (L1000), and 5000 lux (L5000). According to TS EN 12464-1, 500 lux is recommended for routine examinations and 1000 lux for clinical procedures [15]. Color temperature was kept between 3500 and 6500 K to simulate natural daylight conditions. Measurements Obtained from Digital Scans on the Model According to ISO 20896-1:2019, the distances between the four pre-positioned metal projections on the model were determined as described below [16]. The reference points A, B, C, and D were defined as follows: – Point A: the incisal tip of tooth 43 – Point B: mesiobuccal cusp tip of tooth 46 – Point C: mesiobuccal cusp tip of tooth 36 – Point D: the incisal tip of tooth 33 Four linear inter-landmark distances were measured: A–B, B–C, C–D, and D–A, recorded in millimeters across all experimental conditions. The mandibular full-arch phantom model and the reference measurement points used for distance measurements are shown in Figure 1. Measurement Procedures with Digital Scanners The intraoral scanners used in this study were the ITERO Element 5D (Align Technology Inc., Tempe, AZ, USA), the SIRONA CEREC AC Omnicam (Sirona Dental Systems GmbH, Bensheim, Germany), and the SHINING Aoralscan 3 Wireless (SHINING 3D, Hangzhou, China). A total of 240 scans were obtained by performing ten scans for each combination of scanner, shade, and illuminance level (3 scanners × 2 shades × 4 illuminance levels × 10 repetitions). From each scan, four linear distance measurements were recorded, each representing the direct distance between two fixed reference points. Repeatability was assessed by repeating each scanning combination 10 times, and CV% was used to quantify measurement dispersion. Using the MEDIT T500 desktop scanner as the reference instrument, measurements were collected under a single standardized condition. The 10 repeated scans yielded 40 measurements in total (10 repetitions × 4 distances). Given that this device functions as a fixed-reference laboratory tool, its controlled acquisition chamber naturally provided identical conditions throughout all reference scans. All scanning procedures used the OWBP (Occlusal–Wiggling–Buccal–Palatal) scanning protocol. Scanning began with the occlusal surfaces, then used a wiggling motion across the dental arch to capture interproximal regions, and finished with buccal and palatal surfaces. This protocol is reported in the literature to yield high trueness and precision in intraoral digital impressions [17]. Every scanner, shade, and illuminance combination was scanned following the OWBP protocol, which served as a safeguard against systematic bias. To minimize operator-related variability, all scans were performed by a single experienced prosthodontist with more than five years of intraoral scanning practice. The scanning path and its starting point were standardized and maintained throughout all experimental conditions to minimize trajectory-related deviation [18]. Dependent and Independent Variables Accuracy was evaluated using the mean absolute linear deviation (Δmean, µm), representing the average difference between each intraoral scanner’s distance measurements and the MEDIT T500 reference values. Four inter-landmark distances were recorded: AB (≈20.908 mm), BC (≈45.425 mm), CD (≈21.091 mm), and AD (≈27.394 mm). Since the raw data were collected in millimeters, they were converted to micrometers (×1000) to facilitate interpretation and comparison. The absolute deviation for each distance was calculated as Δ = |dIOS − dref|, where dIOS is the distance measured by the intraoral scanner and dref is the reference value. The mean across the four distances (Δmean) was computed as Δmean = (ΔAB + ΔBC + ΔCD + ΔAD) / 4. Clinical acceptability was assessed against the 120 µm threshold, as defined by ISO 20896-1:2019 (an international standard for dental accuracy), and consistent with the criterion proposed for indirect dental restorations [19]. Raw distance deviations for each region (AB, BC, CD, and DA) are available in the Supplementary Tables. For the main statistical analysis, a combined deviation metric (Δmean) was used as the mean of the four regional deviations. Statistical analysis Before inferential analysis, normality of Δmean distributions was examined in each of the 24 experimental cells. Normality was assessed using the Shapiro–Wilk test, supported by visual inspection of P-P and Q-Q plots. The assumption of homogeneity of variances was evaluated using Levene’s test. As all assumptions were satisfied, parametric tests were applied throughout the analysis. A three-way ANOVA (Type III sum of squares) was performed. Scanner type, tooth shade, and illuminance were fixed factors. The statistical evaluation examined the main effects of each factor and their two-way and three-way interactions. Effect sizes were expressed as partial eta-squared (η 2 p), with conventional thresholds used to interpret magnitude (small (0.01–0.06), medium (0.06–0.14), and large (≥0.14)). Significant main effects were followed up with Tukey's HSD post hoc test to pinpoint group-level differences. Where interactions were significant, the analysis proceeded to simple effects, and a Bonferroni correction was applied to pairwise comparisons to control the familywise error rate. Measurement reliability was evaluated using the intraclass correlation coefficient (ICC; two-way mixed model, absolute agreement). A subset of 50 measurements was independently re-evaluated by a second examiner blinded to the primary examiner's results, and re-measured by the primary examiner after a two-week interval. Inter-examiner and intra-examiner ICC values were calculated to evaluate consistency. Among the computed statistics, CV% (expressed as [SD/mean] × 100) was used to assess repeatability. CV% values were calculated from four distance measurements across 10 scans per condition, and the mean CV% was used as the repeatability indicator. Sample size was determined via a priori power analysis (G*Power 3.1), assuming a large effect size (Cohen's f = 0.40; η 2 p ≈ 0.14), consistent with previous studies. At α = 0.05 and power = 0.95, a minimum of n = 6 per cell (N = 144) was needed. The chosen sample of n = 10 per cell (N = 240) gave a substantial safety margin above this minimum. All hypothesis tests were two-tailed (α = 0.05). Statistical analyses were performed in SPSS Version 27 (IBM Corp., Armonk, NY, USA); power analyses in G*Power 3 [20]. Results A total of 24 experimental conditions arose from crossing three scanners with two tooth shades and four illuminance levels. For each condition, measurement deviations (Δmean, µm) of the ITERO Element 5D, SIRONA CEREC AC Omnicam, and SHINING Aoralscan 3 were evaluated relative to the MEDIT T500 reference scanner, with testing carried out under shades A1 and A4 at illuminance levels L100, L500, L1000, and L5000. All values are reported in micrometers (µm) and summarised in Table 1. Mean values above the 120 µm clinical threshold are marked by †. Figure 2 shows the distribution of trueness values across conditions. ITERO Element 5D demonstrated the highest trueness among the three scanners, with a mean deviation of 85.6 ± 32.0 µm (95% CI: 78.6–92.6 µm). SIRONA CEREC AC Omnicam occupied an intermediate position with a mean deviation of 107.7 ± 32.9 μm (95% CI: 100.4–115.0 μm). SHINING Aoralscan 3 exhibited the lowest trueness and the highest mean deviation among the three scanners (122.8 ± 33.4 μm; 95% CI: 115.4–130.3 μm). Any mean value crossing the 120 μm clinical acceptance threshold is indicated by †. The difference between tooth shades A1 (107.3 ± 35.4 µm; 95% CI: 100.9–113.7 µm) and A4 (103.5 ± 36.8 µm; 95% CI: 96.8–110.1 µm) was not significant. The only significant difference in illuminance was between L1000 and L5000 (post hoc, p = 0.038). For SHINING Aoralscan 3 under shade A1, threshold violations occurred at L100 (146.8 µm), L1000 (139.0 µm), and L5000 (121.8 µm). A three-way ANOVA assessed the effects of scanner type, tooth shade, and illuminance level on trueness. The model explained 41.8% of the variance, as shown in Table 2. Scanner type significantly affected trueness outcomes (F(2, 216) = 33.536, p < 0.001, η 2 p = 0.237). Tooth shade did not have a significant effect (F(1, 216) = 1.049, p = 0.307, η 2 p=0.005). Illuminance was significant, though its effect size was small (F(3, 216) = 2.722, p = 0.045, η 2 p = 0.036), as shown in Table 2. All two-way and three-way interactions were statistically significant. The three-way interaction demonstrated that trueness depends on the combined effects of scanner type, tooth shade, and illuminance (F(6, 216) = 5.777, p < 0.001, η 2 p = 0.138). Tukey HSD post hoc testing confirmed that each scanner differed significantly in trueness. ITERO Element 5D had the highest trueness (85.6 ± 32.0 µm), followed by SIRONA CEREC AC Omnicam (107.7 ± 32.9 µm), and SHINING Aoralscan 3 (122.8 ± 33.4 µm). Each scanner was significantly different in trueness (ITERO vs SIRONA: 22.1 µm, p < 0.001; ITERO vs SHINING: 37.2 µm, p < 0.001; SIRONA vs SHINING: 15.2 µm, p = 0.003). ITERO Element 5D had the highest trueness, SIRONA CEREC AC Omnicam was intermediate, and SHINING Aoralscan 3 had the lowest. A significant difference among illuminance levels was observed only between L1000 and L5000 (L1000 = 114.0 µm, L5000 = 99.4 µm). All other pairwise comparisons were not significant. Two-way interactions were further examined to characterise the independent contributions of each factor pair before interpreting the three-way interaction. The interaction between scanner type and tooth shade was significant (F(2, 216) = 4.882, p = 0.008; η 2 p = 0.043), indicating scanner-dependent differences in how shade affected trueness. Estimated marginal means showed that A1 outperformed A4, with lower deviations for ITERO (80.0 vs 91.7 µm) and SHINING (130.6 vs 115.1 µm). However, SIRONA showed the opposite pattern — its deviations were smaller under A4 than A1 (103.7 vs 111.7 µm). SHINING stood out as the only scanner for which the shade effect was statistically significant (F(1, 216) = 5.791, p = 0.017), with A1 breaching the 120 µm clinical limit (130.6 µm†) and A4 remaining just below it (115.1 µm). Shade exerted no statistically significant influence on ITERO (F(1, 216) = 3.493, p = 0.063) or SIRONA (F(1, 216) = 1.530, p = 0.217), and neither scanner exceeded the clinical threshold under either shade condition. The Scanner × Illuminance interaction (F(6, 216) = 4.018, p = 0.001; η 2 p = 0.100) indicated that illuminance affected the three scanners differently. Whether illuminance affected trueness depended on which scanner was examined. ITERO's simple effect was significant (F(3, 216) = 2.881, p = 0.037), with estimated marginal means of 74.0, 86.0, 101.0, and 82.0 µm at L100 through L5000, respectively, none exceeding the clinical limit; only L100 and L1000 differed significantly (p = 0.028). SIRONA did not reach significance (F(3, 216) = 2.377, p = 0.071), and pairwise contrasts were uniformly non-significant, although the L1000 mean of 119.0 µm hovered just under the 120 µm threshold. SHINING's response to illuminance was both statistically strong (F(3, 216) = 5.499, p = 0.001) and clinically meaningful, its means spanning 37.0 µm from a low of 104.0 µm at L5000 to a high of 141.0 µm at L100 (†). The contrast between L100 and L5000 was significant (p < 0.001), as L100 exceeded the clinical threshold. Differences between shade–illuminance combinations were captured by a significant interaction effect (F(3, 216) = 3.492, p = 0.017; η²p = 0.046). When illuminance was low, measurements for A1 and A4 were largely equivalent (L100: 104.0 vs 105.0 µm; L500: 98.0 vs 109.0 µm), and a similar degree of agreement was observed at L1000 (116.0 vs 112.0 µm). At L5000, A4 registered 23.0 µm lower than A1 (88.0 vs 111.0 µm), a divergence absent at lower illuminance levels and consistent with a darker-shade benefit that emerges only under very high ambient light. From a clinical standpoint, the A1 measurement at L1000 (116.0 µm) approached the 120 µm threshold, whereas the A4 reading at L5000 (88.0 µm) remained well within an acceptable range. The three-way interaction (Scanner × Shade × Illuminance) was examined in detail by analysing the trueness profile of each scanner under A1 and A4 conditions across all four illuminance levels (Table 1). Mean values exceeding the 120 µm clinical acceptance threshold are indicated by †. Under shade A1, ITERO Element 5D stayed below the clinical acceptance threshold across all four illuminance levels, confirming mean-level clinical acceptability throughout the full illuminance range. The simple effect of illuminance within ITERO/A1 reached statistical significance (F(3, 216) = 5.694, p = 0.001). Deviations rose progressively from L100 (55.2 µm) to L500 (69.2 µm), L1000 (88.8 µm), and L5000 (105.0 µm), representing a 49.8 µm absolute increase across the range, yet all values remained well within the 120 µm clinical limit. L5000 differed significantly from both L100 (p = 0.001) and L500 (p = 0.037), while all other pairwise comparisons fell short of significance (all p > 0.05). Despite every A1 deviation staying below the clinical threshold, the significant rise at L5000 relative to lower illuminance levels suggests that very high ambient light reduces ITERO trueness for lighter tooth shades, albeit without entering a clinically unacceptable range. ITERO under A4 yielded a markedly different pattern. The illuminance effect within this subgroup was significant (F(3, 216) = 6.419, p < 0.001). At L100, the deviation was 93.5 µm. At L500 it rose to 102.0 µm, and at L1000 it reached 112.3 µm — all within the acceptable range. L5000 broke this trend entirely, bringing the deviation down to 58.9 µm. This drop was significant relative to L100 (p = 0.048), L500 (p = 0.006), and L1000 (p < 0.001), meaning 5000 lux genuinely improved trueness for this shade. The A1 vs A4 difference across ITERO as a whole did not reach significance (p = 0.063), but this masks an important point: the two shades responded to illuminance in opposite directions. L5000 was the worst condition for A1 and the best for A4. That reversal is the most clinically relevant finding this device produced. SIRONA CEREC AC Omnicam showed relatively stable trueness values under shade A1 across the tested illuminance levels. The measured deviations were 110.0 µm at L100, 110.5 µm at L500, 120.8 µm at L1000, and 105.5 µm at L5000, corresponding to an overall range of 15.3 µm across the full illuminance spectrum. Among these conditions, L1000 was the only level at which the clinical threshold was exceeded, with a mean deviation of 120.8 µm. The effect of illuminance within the SIRONA/A1 condition was not statistically significant (F(3, 216) = 0.497, p = 0.685), and all pairwise comparisons returned p = 1.000. The presence of a threshold violation despite the absence of statistically significant pairwise differences can be explained by the limited variability between conditions. Specifically, the relatively narrow range of 15.3 µm provides little separation between illuminance levels, reducing the ability of pairwise statistical contrasts to detect differences. For this reason, the clinical relevance of the L1000 finding should be considered independently of the p-value. Within the SIRONA system, the illuminance effect under shade A4 reached statistical significance (F(3, 216) = 3.695, p = 0.013), although none of the individual pairwise comparisons were significant. At lower illuminance levels, deviations remained relatively low, measuring 87.5 µm at L100 and 89.5 µm at L500. At higher illuminance levels, the values increased to 117.8 µm at L1000 and 120.0 µm at L5000, approaching but not exceeding the 120 µm threshold. Overall, the increase of 32.5 µm from L100 to L5000 represents a clinically notable change, even though pairwise statistical testing did not reveal significant contrasts. The global comparison between shades within the SIRONA system was not statistically significant (p = 0.217). Nevertheless, at lower illuminance levels—particularly L100 and L500—shade A4 demonstrated a clinically meaningful performance advantage. Among all devices tested, SHINING Aoralscan 3 generated the most clinically critical findings under shade A1. Threshold violations were recorded at three of the four illuminance levels: L100 (146.8 µm), L1000 (139.0 µm), and L5000 (121.8 µm), with only L500 (115.0 µm) falling within the acceptable range. The illuminance effect within SHINING/A1 did not reach statistical significance (F(3, 216) = 2.602, p = 0.053), missing the α = 0.05 cutoff by a narrow margin. Pairwise comparisons similarly returned no significant contrasts (all p > 0.05; minimum p = 0.089 for L100 vs L500). These non-significant results should not be interpreted as evidence of acceptable performance. Three of the four illuminance levels exceeded the clinical threshold, and the minimum individual acceptance rate reached only 10% at L1000. In this context, statistical non-significance reflects the similarity among clinically unacceptable values rather than any genuine equivalence across acceptable ones. Shade A4 brought a clinically meaningful improvement. A highly significant illuminance effect was found within SHINING/A4 (F(3, 216) = 6.897, p < 0.001). Deviations at L1000 (105.5 µm) and L5000 (85.5 µm) fell comfortably below the threshold, whereas L100 (134.5 µm) and L500 (134.8 µm) continued to exceed it. The most striking pairwise differences under A4 were between L5000 and L100 (p = 0.001) and between L5000 and L500 (p = 0.001), confirming that the clinical benefit of shade A4 for SHINING is concentrated at high illuminance levels. The improvement from A1 to A4 was statistically significant (p = 0.017). The reduction from 121.8 µm under A1 to 85.5 µm under A4 at L5000 represents a notable improvement. Repeatability and Measurement Reliability Repeatability was evaluated using the coefficient of variation (CV%) calculated for each scanner–shade–illuminance combination. Across all 24 experimental conditions, CV% values ranged from 0.13% to 0.33%, with an overall mean of 0.25%, indicating excellent repeatability for all combinations. At the device level, mean CV% values were highly consistent across the three scanners, ranging from 0.24% to 0.26%. These findings indicate that the substantial differences in trueness between devices are more likely attributable to systematic scanner-specific deviations than to differences in measurement precision, as all three scanners exhibited comparable levels of repeatability. Of particular note, SHINING Aoralscan 3 achieved CV% values comparable to those of ITERO despite producing considerably higher mean deviations, revealing that precision and trueness are distinct as performance properties. Inter-examiner ICC values ranged from 0.952 to 0.975, and intra-examiner ICC values ranged from 0.971 to 0.980, both indicating excellent reliability (ICC > 0.90). To complement the three-way ANOVA, the percentage of individual measurements below the 120 µm clinical threshold was calculated for each scanner–shade–illuminance combination. This provides clinical reliability data at the individual measurement level beyond group means (Table 1). Across scanners, ITERO Element 5D demonstrated the highest individual-measurement reliability, with 68 of 80 measurements (85.0%) falling below the clinical threshold. SIRONA CEREC AC Omnicam achieved moderate reliability (55/80; 68.8%), while SHINING Aoralscan 3 produced the lowest device-level acceptance rate (37/80; 46.3%). Six conditions achieved 100% individual acceptance: ITERO/A1/L100, ITERO/A1/L500, ITERO/A4/L100, ITERO/A4/L5000, SIRONA/A4/L100, and SHINING/A4/L5000. The most clinically critical finding was identified for SHINING/A1/L1000, in which only one measurement (10%) fell below the clinical threshold, while nine measurements (90%) exceeded 120 µm. This combination represents the highest clinical risk condition identified in the present study and is considered unsuitable for clinical use. SHINING Aoralscan 3 demonstrated markedly shade-dependent individual acceptance rates: 32.5% under A1 versus 60.0% under A4, with the highest performance at A4/L5000 (100% individual acceptance). An analysis of individual-measurement acceptance rates substantially complements the group-means delta table. For example, ITERO/A4/L500 yielded a mean deviation of 102.0 µm, which falls below the 120 µm threshold; however, the individual acceptance rate for this condition was only 60%, indicating that 4 of 10 measurements exceeded the clinical limit despite a clinically acceptable group mean. This finding reveals the limitations of group-mean-based assessment alone and supports reporting both mean values and individual-measurement distributions in intraoral scanner trueness research. ITERO was the only scanner to maintain mean-level clinical acceptability across all eight shade–illuminance combinations, establishing it as the most clinically reliable device in this study. SIRONA CEREC AC Omnicam exceeded the clinical threshold only at A1/L1000 (120.8 µm†); all other conditions were within the 120 µm limit, including A4/L5000, which met but did not exceed the threshold. Discussion This in vitro study examined the combined effects of scanner type, tooth shade, and ambient illuminance on intraoral scanner trueness using a full-factorial three-way design. Among the three factors, scanner type emerged as the dominant source of variance (η 2 p = 0.237). Although illuminance reached statistical significance, its effect size was small (η 2 p = 0.036), suggesting that its influence on trueness should be interpreted in the context of device and shade characteristics. The Shade × Illuminance interaction was significant (η 2 p = 0.046), showing that tooth shade and illuminance did not act independently on trueness. The three-way interaction (η 2 p = 0.138) further showed that the combined shade–illuminance effect varied across scanner types. In other words, illuminance may not be a stand-alone predictor. Its impact on trueness depends on both the scanner type and tooth shade. At the clinical level, individual-measurement analysis revealed that group-mean deviations below the 120 µm threshold did not necessarily ensure clinically acceptable individual outcomes. In addition, no single illuminance level proved optimal across all device–shade combinations. Darker tooth shades altered the optical reflectivity and light-scattering properties of the scanned surface, affecting image acquisition and surface reconstruction. Previous reports have demonstrated an inverse correlation between the L* value of scanned materials and scanner trueness. Our data extend this relationship by showing that shade-related trueness loss is further modulated by both illuminance level and scanner type. Inter-device differences were consistent with the underlying technologies [ 7 ]. ITERO Element 5D uses confocal imaging, SIRONA CEREC Omnicam uses triangulation projection, and SHINING Aoralscan 3 uses structured light. Each system shows different sensitivity to surface optical properties and ambient photon flux [ 5 , 21 , 22 ]. Differences in stitching algorithms and surface registration may also contribute to full-arch deviations [ 9 ]. The superior performance of ITERO across conditions was consistent with previous reports showing device-dependent differences in scanning accuracy under varying lighting conditions [ 23 ]. Lower ambient light has been associated with greater accuracy, which aligns with our A1 findings [ 24 ]. However, this pattern did not apply to darker shades. For A4, ITERO performed best at L5000 and worst at L1000 — a reversal that would not be detectable in single-shade study designs [ 24 ]. The combined effect of ambient and internal scanner light has been shown to influence accuracy differently across devices [ 25 ]. The higher Δmean values observed in this study relative to surface-based 3D RMS studies reflect the nature of landmark distance deviation as a measure of total geometric error across the full arch [ 9 ]. A systematic review has shown that ambient light affects scanner accuracy in a device-dependent manner [ 26 ]. In addition, both illuminance level and colour temperature have been reported to influence intraoral scanning trueness, with optimal settings varying across systems [ 27 ]. Our results further demonstrate that illuminance effects cannot be interpreted independently. Instead, they can be evaluated within the joint framework of scanner type and tooth shade. In this context, the observed higher-order interaction structure may help explain discrepancies between previous studies, particularly those that evaluated lighting conditions without incorporating shade-related variation. No single illuminance level was optimal for all device–shade combinations, highlighting the importance of examining factor interactions, since important differences may be missed when only main effects are considered [ 26 , 27 , 28 , 29 , 30 ]. A shade-dependent crossover pattern was observed with ITERO Element 5D. Under A1, trueness declined progressively as illuminance increased from L100 to L5000, yet all values remained below the clinical threshold. Conversely, under A4 conditions, the pattern reversed. The highest accuracy was achieved at L5000 (58.9 µm; 100% individual acceptance), while intermediate illuminance levels showed poorer performance. This indicates a non-monotonic response specific to 5000 lux. This behaviour may be explained by the confocal imaging principle of ITERO. Lighter shades tend to produce greater specular reflection under high illuminance, whereas darker shades may benefit from increased photon flux [ 5 ]. Prior studies identified optimal accuracy at 500 lux for a single scanner [ 31 ] and at 100 lux for the confocal Element 5D, consistent with our A1 findings [ 30 ]. The shade-related inversion observed under A4 has not been previously reported and represents a clinically relevant pattern that single-shade study designs cannot detect [ 24 , 30 , 31 ]. SHINING Aoralscan 3 exhibited the most pronounced shade-dependent trueness profile. Under A1 conditions, three of four illuminance levels exceeded the clinical threshold, with individual acceptance as low as 10% at L1000. Under A4 conditions, performance improved markedly at higher illuminance levels, reaching 100% individual acceptance at L5000. This pattern aligned with the previously reported inverse relationship between L* value and scanner trueness, whereby lighter shades generate greater surface reflection and increase the probability of image acquisition errors [ 7 ]. However, darker shading did not uniformly improve performance. Threshold violations persisted at L100 and L500 under A4, indicating a non-monotonic interaction between shade and illuminance for this device. The 120 µm threshold, originally established for cement film thickness, can reveal failures at the individual level that group-mean reporting alone cannot capture [ 19 ]. Previous studies have reported that tooth shade affects accuracy across lighting conditions [ 29 ]. However, the three-way interaction structure identified here revealed condition-specific failure patterns that single- or two-factor designs cannot detect. The absence of a significant main effect for tooth shade may appear to contradict the pronounced shade-related differences observed at the device level. This apparent inconsistency reflects a masking effect in which opposing directional changes across scanners were cancelled at the aggregated main-effect level. Crucially, tooth shade in this study was not a passive covariate but an experimentally manipulated factor: the same physical model was recoloured from A1 to A4 under controlled spectrophotometric verification, enabling direct isolation of shade as an independent variable. The significant Shade × Illuminance interaction (η 2 p = 0.046) demonstrated that shade effects on trueness varied across illuminance levels, with the largest A1–A4 divergence emerging at L5000. The three-way interaction further revealed that this pattern is scanner-dependent: under ITERO at 5000 lux, A4 trueness improved markedly while A1 trueness simultaneously declined, producing a crossover that suppressed the shade main effect when data were aggregated. Interpreting a non-significant main effect for shade as evidence of no clinically relevant shade influence when significant interaction terms are present, and underscores the necessity of full-factorial designs for detecting higher-order interaction structures. SIRONA CEREC AC Omnicam demonstrated the most stable trueness profile across illuminance levels, consistent with device-dependent illuminance responses reported for triangulation-based systems, which may exhibit lower sensitivity to external photon flux than confocal-based devices [ 25 , 30 , 32 , 33 ]. Under A1, illuminance changes produced only marginal variation, yet L1000 was the sole condition exceeding the clinical threshold, and individual acceptance remained at or below 70% throughout, indicating borderline clinical reliability. Under A4, a shade-dependent crossover emerged at L5000 — mirroring, in the opposite direction, the pattern observed for ITERO — where A4 deviations rose to the threshold level while A1 deviations remained lower. Our A1 findings were partly consistent with earlier reports [ 33 ]. The markedly reduced individual acceptance at A4/L5000 (40%), despite a mean deviation at the threshold, confirms that illuminance tolerance profiles are both technology- and shade-dependent. Precision was uniformly high across all 24 conditions regardless of scanner, shade, or illuminance level (CV%: 0.13–0.33%; mean: 0.25%), with negligible between-device differences (ITERO: 0.24%; SIRONA and SHINING: 0.26% each) [ 9 , 10 ]. These findings indicated that the substantial trueness differences observed across scanner types and experimental conditions reflected systematic device-specific deviations rather than random measurement variability, consistent with the conceptual distinction between trueness and precision as defined by ISO 20896-1:2019 [ 9 , 16 , 22 ]. Intraoral scanners acquire multiple sequential images that are digitally stitched together to reconstruct the complete surface geometry. Although this approach enables rapid full-arch digitisation, small alignment deviations between consecutive images may accumulate along the scanning path, resulting in cumulative stitching errors [ 8 ]. This phenomenon represents an inherent limitation of intraoral scanning systems and may partially explain the trueness deviations observed in the present study. Furthermore, high ambient illuminance may exacerbate stitching errors by reducing image contrast and signal-to-noise ratio during sequential frame acquisition, providing an additional mechanistic pathway through which illuminance influences scanning trueness [ 8 ]. The results have actionable implications for scanner-specific clinical protocols. When using ITERO Element 5D with lighter tooth shades, reducing ambient illuminance to the 100–500 lux range optimises trueness: both L100 (55.2 µm) and L500 (69.2 µm) achieved 100% individual acceptance, making either condition suitable for routine clinical use. At higher illuminance levels, individual reliability progressively declined — to 90% at L1000 and 70% at L5000 — indicating that even mean-acceptable conditions carried a non-trivial proportion of out-of-threshold measurements as ambient light increased. The shade-dependent crossover pattern observed for this device dictates a markedly different approach for darker shades: under A4, 5000 lux yielded the most favourable outcome (58.9 µm; 100% individual acceptance), and L100 was also clinically acceptable (93.5 µm; 100% individual acceptance). The intermediate conditions of L500 and L1000 should be avoided for A4 scanning, as both yielded only 60% individual acceptance despite sub-threshold group means of 102.0 and 112.3 µm — a finding that group-mean analysis alone would not reveal. Among the three devices, SHINING Aoralscan 3 showed the most restrictive clinical profile. For A1-range shades, three of the four illuminance levels tested produced mean deviations above the clinical threshold — L100 (146.8 µm; 30% individual acceptance), L1000 (139.0 µm; 10% individual acceptance), and L5000 (121.8 µm; 40% individual acceptance) — and should be considered unsuitable for clinical use. Although L500 remained below the mean-level threshold (115.0 µm), its individual acceptance rate of only 50% means that one in two measurements still exceeded the clinical limit. This failure rate warrants considerable caution. Clinicians using this scanner with A1-range shades should prefer L500 where feasible, while acknowledging that no tested condition achieved reliably acceptable individual-level performance. For A4-range shades, the lower illuminance levels remained problematic: L100 (134.5 µm; 30% individual acceptance) and L500 (134.8 µm; 40% individual acceptance) both exceeded the threshold. Trueness improved meaningfully from L1000 onward (105.5 µm; 70% individual acceptance), reaching its best performance at L5000 (85.5 µm; 100% individual acceptance). Darker shading, therefore, does not guarantee acceptable results with this scanner unless combined with high ambient illuminance. SIRONA CEREC AC Omnicam demonstrated generally acceptable performance with one notable exception: A1/L1000 (120.8 µm; 50% individual acceptance) exceeded the mean-level threshold and should be avoided. Under all remaining A1 conditions, individual acceptance rates were consistently at or below 70%, suggesting that borderline reliability persists even when group means remain within the acceptable range. For A4, performance was more favourable at lower illuminance levels — L100 (87.5 µm; 100% individual acceptance) and L500 (89.5 µm; 80%) both performed well — but individual acceptance declined to 70% at L1000 and to only 40% at L5000, where the mean deviation reached exactly 120.0 µm. Both higher illuminance conditions warrant clinical caution for this scanner, even in the absence of a mean-level threshold violation at L5000. The full-factorial three-way design used in this study offers a methodological advantage over the single- and two-factor approaches common in the literature [ 25 , 31 , 32 ]. By simultaneously manipulating scanner, shade, and illuminance across all combinations, the design enabled detection of interaction effects that would be invisible in single-variable protocols. This is particularly relevant, as the highest-risk condition—SHINING/A1/L1000 with only 10% individual acceptance—could not have been predicted based on the lighting effect alone. Only one significant pairwise difference between illuminance levels was identified, and this analysis provided no information on the direction or clinical magnitude of effects at the scanner × shade level. The robustness of the observed interaction effects is supported by their large effect sizes and consistent patterns across conditions. Several limitations warrant acknowledgement. The phantom model design, while enabling precise environmental control, precludes direct extrapolation to the clinical intraoral environment, where factors such as saliva, soft tissue reflections, patient movement, and operator skill introduce additional variance [ 34 ]. Only two shades from the VITA classical scale were evaluated, and the full chromatic range may yield different scanner-specific interaction patterns. Given the increasing prevalence of tooth whitening in clinical practice, future studies should prioritise the inclusion of high-luminosity bleached shades (e.g., B1, OM1), which represent particularly challenging conditions for structured-light and confocal systems due to their elevated specular reflectance. Colour temperature of the ambient light source was varied within the 3500–6500 K range to simulate natural daylight conditions; the independent and joint effects of specific colour temperature levels and illuminance were not systematically isolated in the present design and represent an important variable for future study [ 27 , 30 ]. The repeatability metric, CV% of landmark distances, is not directly comparable to full-surface 3D RMS deviation used in many published studies, and cross-study quantitative comparisons must therefore be made with caution. Finally, only one model geometry was scanned, and the influence of preparation design, arch complexity, and scan span on the observed interactions remains to be investigated. Conclusion These findings indicate that the clinical performance of an intraoral scanner cannot be characterised solely by device specifications. Identical ambient conditions yielded markedly different outcomes — ranging from complete individual acceptance to only 30% acceptance — within the same lux level. Future research should incorporate in vivo designs across diverse patient populations and extend the shade range to include the full VITA classical and 3D-Master scales. Studies systematically comparing confocal, triangulation, and structured-light technologies under matched conditions would further clarify the mechanistic basis of the technology-dependent illuminance responses observed here [ 35 ]. The integration of individual-measurement-level acceptance analysis alongside group means should become standard practice in intraoral scanner trueness research, as group means may mask clinically significant failure patterns at the individual level. Abbreviations ANOVA : Analysis of Variance CI : Confidence Interval CV% : Coefficient of Variation (%) HSD : Honestly Significant Difference ICC : Intraclass Correlation Coefficient IOS : Intraoral Scanner ISO : International Organization for Standardization LED : Light-Emitting Diode OWBP : Occlusal–Wiggling–Buccal–Palatal RMS : Root Mean Square SD : Standard Deviation SEM : Standard Error of the Mean Δmean : Mean Absolute Landmark Distance Deviation η²p : Partial Eta-Squared Declarations Acknowledgements We thank the Proofreading & Editing Office of the Dean for Research at Erciyes University for this manuscript's copyediting and proofreading service. Authors’ contributions E.O. conceived and designed the study, performed the experiments, collected the data, and wrote the manuscript. O.O. conducted the statistical analyses and contributed to data interpretation. A.G. contributed to the study design, supervised the research, and critically revised the manuscript. All authors reviewed and approved the final manuscript. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Ethics approval and consent to participate This in vitro study did not involve human participants or animals and therefore did not require ethics committee approval. Consent for Publication Not applicable. Competing interests The authors declare that they have no competing interests. References Mörmann WH. The evolution of CEREC system. J Am Dent Assoc. 2006;137(9 Suppl):7S–13S. Boeddinghaus M, Breloer ES, Rehmann P, Wöstmann B. Accuracy of single-tooth restorations based on intraoral digital and conventional impressions in patients. Clin Oral Investig. 2015;19:2027–34. Donovan TE, Chee WW. 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Tables Table 1 Trueness (Δmean, µm) and Individual Acceptance Rates (%) of Three Intraoral Scanners Across Tooth Shade and Ambient Illuminance Conditions Scanner Shade Illuminance Mean (µm) SD (µm) Min (µm) Max (µm) Acceptance Scanner ITERO A1 L100 55.2 15.1 35.0 75.0 100% 90.0% L500 69.2 15.8 40.0 92.5 100% L1000 88.8 26.5 42.5 135.0 90% L5000 105.0 28.0 52.5 150.0 70% A4 L100 93.5 23.1 40.0 120.0 100% 80.0% L500 102.0 38.7 52.5 155.0 60% L1000 112.3 24.3 75.0 147.5 60% L5000 58.9 26.7 27.5 105.0 100% SIRONA A1 L100 110.0 24.1 80.0 157.5 70% 65.0% L500 110.5 19.8 85.0 140.0 70% L1000 120.8† 22.8 92.5 170.0 50% L5000 105.5 20.7 72.5 135.0 70% A4 L100 87.5 19.3 50.0 115.0 100% 72.5% L500 89.5 33.7 47.5 145.0 80% L1000 117.8 34.4 70.0 175.0 70% L5000 120.0 59.7 35.0 210.0 40% SHINING A1 L100 146.8† 37.7 92.5 202.5 30%‡ 32.5% L500 115.0 40.8 45.0 160.0 50% L1000 139.0† 16.9 115.0 170.0 10%‡ L5000 121.8† 30.3 75.0 182.5 40% A4 L100 134.5† 26.0 95.0 175.0 30%‡ 60.0% L500 134.8† 21.6 115.0 172.5 40% L1000 105.5 27.4 65.0 162.5 70% L5000 85.5 20.4 57.5 120.0 100% SD: standard deviation; Δmean: mean absolute deviation (µm); Min: minimum observed Δmean (µm); Max: maximum observed Δmean (µm); n = 10 per cell. † mean exceeds 120 µm clinical acceptance threshold (ISO 20896-1:2019). ‡ individual acceptance rate <40% (high clinical risk). Overall Mean (%): mean individual acceptance rate across all four illuminance levels per scanner–shade combination. Table 2 Three-way ANOVA results evaluating the effects of scanner type, tooth shade, and illuminance level on Δmean values Source df F p η 2 p Effect Size Scanner 2 33.536 <0.001* 0.237 Large Tooth Shade 1 1.049 0.307 0.005 Negligible Illuminance Level 3 2.722 0.045* 0.036 Small Scanner × Shade 2 4.882 0.008* 0.043 Small Scanner × Illuminance 6 4.018 0.001* 0.100 Medium Shade × Illuminance 3 3.492 0.017* 0.046 Small Scanner × Shade × Illuminance 6 5.777 <0.001* 0.138 Medium df: degrees of freedom, η 2 p: partial eta squared, effect size benchmarks: 0.14 large, *p < 0.05 Additional Declarations No competing interests reported. Supplementary Files SupplementaryTablesBMC.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 06 May, 2026 Reviews received at journal 29 Apr, 2026 Reviewers agreed at journal 29 Apr, 2026 Reviews received at journal 27 Apr, 2026 Reviewers agreed at journal 27 Apr, 2026 Reviewers agreed at journal 27 Apr, 2026 Reviewers invited by journal 15 Apr, 2026 Editor invited by journal 13 Apr, 2026 Editor assigned by journal 10 Apr, 2026 Submission checks completed at journal 10 Apr, 2026 First submitted to journal 05 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9329206","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":627459091,"identity":"7d609152-d1da-4c16-9f7c-f969a532d49f","order_by":0,"name":"EREN OZTURK","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA50lEQVRIie3PMQrCMBSA4YQH7RLrmk5eQekkVHoWKcTF3kEoxEWd7eQtxFEJZPIGGRwKzi0uVRRsqyAOtnYTzD+8ZHgfIQjpdL/Y9nUFlOTTMOuIfJ4kJ3hZEGhCgDweq846hDJJN67n0SB23Mu6YwHCSTr+TGxp+FG0Z0DoyPGDhepxQGBH68+kK4kDLS4MQhmIYKZwTgxoVZL2CW5ckJL0Z8r7ghAAzAUtiI8yNawltmQOnnPWJfsj9OYT5XPAYeVfLCFidOauZ04Z0OyqBqtpuEvSCvIe5uWcfLtfdG2yrNPpdP/SHZz4SJ9CfF1QAAAAAElFTkSuQmCC","orcid":"","institution":"Erciyes University","correspondingAuthor":true,"prefix":"","firstName":"EREN","middleName":"","lastName":"OZTURK","suffix":""},{"id":627459092,"identity":"43f94e3f-5b65-4f5e-816f-b7f0875eece6","order_by":1,"name":"ORHUN OZTURK","email":"","orcid":"","institution":"Hacettepe University Faculty of Medicine","correspondingAuthor":false,"prefix":"","firstName":"ORHUN","middleName":"","lastName":"OZTURK","suffix":""},{"id":627459093,"identity":"405cb3b1-c048-4a03-a2e6-f41a0f2c2f3d","order_by":2,"name":"AYSEGUL GULERYUZ","email":"","orcid":"","institution":"Erciyes University","correspondingAuthor":false,"prefix":"","firstName":"AYSEGUL","middleName":"","lastName":"GULERYUZ","suffix":""}],"badges":[],"createdAt":"2026-04-06 02:38:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9329206/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9329206/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107868786,"identity":"88af3578-6593-4f19-877e-2f8607ab7116","added_by":"auto","created_at":"2026-04-27 07:33:52","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":342391,"visible":true,"origin":"","legend":"\u003cp\u003eMandibular full-arch phantom model and reference measurement points (A–D) used for distance analysis.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9329206/v1/a09ae5276801e1c4d306c3bc.png"},{"id":107675616,"identity":"5e259409-ed06-41f6-a883-327d281cca7f","added_by":"auto","created_at":"2026-04-24 00:44:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":329556,"visible":true,"origin":"","legend":"\u003cp\u003eTrueness (Δmean, µm) and Individual Acceptance Rates (%) of Three Intraoral Scanners by Tooth Shade and Ambient Illuminance Level.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003ePanels A–B: mean Δmean ± SD (n = 10 per cell); error bars indicate ±1 SD; dashed line: 120 µm clinical acceptance threshold; † Δmean \u0026gt; 120 µm. Panels C–D: percentage of individual measurements falling below the 120 µm threshold; dotted line: 40% high-risk threshold; ‡ acceptance rate \u0026lt;40%. Fill patterns: white = ITERO Element 5D; hatched (///) = SIRONA CEREC AC Omnicam; cross-hatched (×) = SHINING Aoralscan 3. Left panels (A, C): tooth shade A1; right panels (B, D): tooth shade A4.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9329206/v1/cd4397411e2947aaed89569d.png"},{"id":107706298,"identity":"45ba54e6-7298-498a-b543-9152fc86e80c","added_by":"auto","created_at":"2026-04-24 09:17:51","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":146740,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of ambient illuminance on intraoral scanner trueness (Δmean) stratified by scanner type and tooth shade.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003ePanel A: tooth shade A1; Panel B: tooth shade A4. Each data point represents the mean Δmean (µm) of n = 10 scans per condition; shaded bands indicate ±1 standard error of the mean (SEM). Circle (●): ITERO Element 5D; square (■): SIRONA CEREC AC Omnicam; triangle (▲): SHINING Aoralscan 3. The x-axis is log-scaled. The horizontal dotted line denotes the 120 µm clinical acceptance threshold (ISO 20896-1:2019). † Δmean exceeds the 120 µm clinical acceptance threshold. Δmean, mean absolute landmark distance deviation.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9329206/v1/089b8b241ca712369d1d30f4.png"},{"id":107871667,"identity":"b0cd1eef-0113-4093-81ff-f8fa4977c117","added_by":"auto","created_at":"2026-04-27 07:53:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1200661,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9329206/v1/5e3f010b-5970-4978-88d8-b5cb97f6ddd7.pdf"},{"id":107675614,"identity":"15d14fab-a9a9-41b4-813f-113b6fb6603e","added_by":"auto","created_at":"2026-04-24 00:44:30","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":19847,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryTablesBMC.docx","url":"https://assets-eu.researchsquare.com/files/rs-9329206/v1/281f6620548d5d518d25b77e.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Tooth Shade and Ambient Illuminance Interact to Affect the Trueness and Repeatability of Intraoral Scanners: A Full-Factorial Experimental Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIntraoral scanning has evolved significantly in digital dentistry over the past three decades. The CEREC system, introduced in the 1980s, has seen significant advancements in hardware and software, resulting in increased compactness, accuracy, and user-friendliness [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Subsequent generations of intraoral scanners have broadened their clinical applications, progressing from single-unit restorations to full-arch digital impressions for a range of prosthodontic indications [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn prosthetic treatment, accurate transfer of tooth and soft-tissue anatomy is critical for the fabrication of clinically acceptable indirect restorations [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Intraoral scanners, which employ a range of optical imaging technologies, have become integral to contemporary clinical workflows and offer well-documented advantages over conventional impression techniques, including improved repeatability, reduced procedural errors, and greater patient comfort [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Realizing these benefits requires both high trueness \u0026mdash; defined as the closeness of agreement between scan data and true geometry \u0026mdash; and high repeatability, as defined by ISO 20896-1:2019 [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Both parameters are susceptible to a range of technical and environmental factors, including scanning protocol, calibration frequency, ambient illuminance, restorative material surface properties, and the presence of mobile soft tissues [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRecent studies have also explored how various factors influence intraoral scanner performance. Although prior studies have established that ambient illuminance influences intraoral scanning trueness and that tooth shade may modulate scanner performance under varying lighting conditions, no previous study has systematically examined their combined interaction within a single controlled design [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Furthermore, no study has applied controlled spectrophotometric shade standardization across all scanner\u0026ndash;illuminance combinations using the same physical model. This methodological gap precludes direct isolation of shade as an independent variable. As a result, clinicians currently lack device- and shade-specific illuminance recommendations [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eGiven this limitation, the present study was designed to evaluate the individual and combined effects of scanner type, tooth shade, and ambient illuminance on trueness and repeatability across a full-factorial experimental design. Three intraoral scanners were assessed under two standardized tooth shades and four illuminance levels using a phantom model with controlled spectrophotometric shade verification. In addition to conventional group-mean analysis, individual-measurement-level clinical acceptance rates were computed to detect failure patterns that group-level statistics alone may obscure [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. This approach goes beyond conventional group-mean reporting and provides clinicians with practical, device-specific, and shade-specific guidance for scanning protocols.\u003c/p\u003e \u003cp\u003eWhile newer generations of intraoral scanners have been introduced, the present study does not aim to provide a device-specific comparison limited to particular commercial models. Instead, it focuses on fundamental relationships between scanner type, surface optical properties, and ambient illuminance. These underlying mechanisms are inherent to optical acquisition systems and are not restricted to a single device generation. Therefore, the findings of this study may provide insights that remain relevant beyond the specific scanners evaluated, contributing to a broader understanding of intraoral scanning performance under varying clinical conditions.\u003c/p\u003e \u003cp\u003eThe null hypothesis was that scanner type, tooth shade, and ambient illuminance each exerted independent effects on intraoral scanner trueness, with no statistically significant interactions among them. This expectation was informed by prior studies that examined these variables in isolation, providing limited evidence of strong interdependencies. Accordingly, each factor was anticipated to contribute independently to trueness variance, without meaningfully modulating the effect of the other variables.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e\u003cstrong\u003eStudy Design, Acquisition of Reference Data, and Model Preparation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAn in vitro study design was used to allow strict control of optical and environmental variables, particularly illuminance and surface shade. A full-arch mandibular phantom jaw model (Fuji Phantom Typodont) was used, as in vivo conditions can introduce several uncontrollable factors. These include saliva, patient movement, soft tissue dynamics, and variations in reflective surfaces. Such factors can obscure the independent and combined effects of scanner optics, tooth shade, and ambient lighting on measurement trueness.\u003c/p\u003e\n\u003cp\u003eMetal projections were created on the incisal tips of the canine teeth and the mesiobuccal cusps of the first molars on the mandibular phantom model to standardize the measurements. The phantom teeth were adjusted to A1 and A4 shades using the Vita Classical shade guide and the Spectro Shade device (Spectro Shade Micro, MHT S.p.A., Milan, Italy).\u003c/p\u003e\n\u003cp\u003eHigh-precision reference data (gold standard) were obtained from the phantom model using the MEDIT T500 desktop laboratory scanner (Medit Inc., Seoul, Korea). This device is known for its high resolution and accuracy in dental applications [12]. Desktop laboratory scanners, such as the MEDIT T500, are commonly used as reference systems in digital dentistry studies due to their superior trueness and resolution compared to intraoral scanners. The scanner uses structured light with a blue LED, with reported accuracy of \u0026lt;7 \u0026micro;m and a depth resolution of 0.1 mm. All measurement data were recorded in STL format using CloudCompare software (version 2.14) [13].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdjustment of Color Conditions for Scanning Data\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe phantom mandibular jaw model was initially in the A1 shade and scanned under this condition. The model\u0026apos;s teeth were then recolored to A4 using the GC Optiglaze Color kit (GC Europe N.V.) according to the manufacturer\u0026rsquo;s protocol. Two successive layers were applied to all tooth surfaces with a brush applicator, and each layer was light-cured for 20 seconds using a dental curing unit. Shade accuracy was verified using the Spectro Shade device both before and after the recoloring procedure.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eDetermination of Ambient and Light Conditions for Digital Scanning\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll scans were performed at a controlled room temperature of 24 \u0026deg;C, which is within the typical range for dental operatory conditions (22\u0026ndash;26 \u0026deg;C) [14]. Maintaining a stable temperature helped reduce potential thermal changes in the phantom model. This also ensured that any differences in the measurements were mainly due to experimental factors, such as scanner type, tooth shade, and illuminance, rather than temperature fluctuations.\u003c/p\u003e\n\u003cp\u003eA Govee GBWW Smart LED Bulb lighting system was used to control illuminance and color temperature. The phantom models were placed inside a sealed box with a matte-coated interior surface to provide uniform lighting conditions. During scanning, light levels were measured around the scanning head using a lux meter (Testo AG, Germany) and maintained constant throughout the scans.\u003c/p\u003e\n\u003cp\u003eIlluminance levels were chosen to represent the range commonly encountered in clinical dental settings: 100 lux (L100), 500 lux (L500), 1000 lux (L1000), and 5000 lux (L5000). According to TS EN 12464-1, 500 lux is recommended for routine examinations and 1000 lux for clinical procedures [15]. Color temperature was kept between 3500 and 6500 K to simulate natural daylight conditions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMeasurements Obtained from Digital Scans on the Model\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAccording to ISO 20896-1:2019, the distances between the four pre-positioned metal projections on the model were determined as described below [16]. The reference points A, B, C, and D were defined as follows:\u003c/p\u003e\n\u003cp\u003e\u0026ndash; Point A: the incisal tip of tooth 43\u003c/p\u003e\n\u003cp\u003e\u0026ndash; Point B: mesiobuccal cusp tip of tooth 46\u003c/p\u003e\n\u003cp\u003e\u0026ndash; Point C: mesiobuccal cusp tip of tooth 36\u003c/p\u003e\n\u003cp\u003e\u0026ndash; Point D: the incisal tip of tooth 33\u003c/p\u003e\n\u003cp\u003eFour linear inter-landmark distances were measured: A\u0026ndash;B, B\u0026ndash;C, C\u0026ndash;D, and D\u0026ndash;A, recorded in millimeters across all experimental conditions. The mandibular full-arch phantom model and the reference measurement points used for distance measurements are shown in Figure 1.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eMeasurement Procedures with Digital Scanners\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe intraoral scanners used in this study were the ITERO Element 5D (Align Technology Inc., Tempe, AZ, USA), the SIRONA CEREC AC Omnicam (Sirona Dental Systems GmbH, Bensheim, Germany), and the SHINING Aoralscan 3 Wireless (SHINING 3D, Hangzhou, China).\u003c/p\u003e\n\u003cp\u003eA total of 240 scans were obtained by performing ten scans for each combination of scanner, shade, and illuminance level (3 scanners \u0026times; 2 shades \u0026times; 4 illuminance levels \u0026times; 10 repetitions). From each scan, four linear distance measurements were recorded, each representing the direct distance between two fixed reference points. Repeatability was assessed by repeating each scanning combination 10 times, and CV% was used to quantify measurement dispersion. \u003c/p\u003e\n\u003cp\u003eUsing the MEDIT T500 desktop scanner as the reference instrument, measurements were collected under a single standardized condition. The 10 repeated scans yielded 40 measurements in total (10 repetitions \u0026times; 4 distances). Given that this device functions as a fixed-reference laboratory tool, its controlled acquisition chamber naturally provided identical conditions throughout all reference scans.\u003c/p\u003e\n\u003cp\u003eAll scanning procedures used the OWBP (Occlusal\u0026ndash;Wiggling\u0026ndash;Buccal\u0026ndash;Palatal) scanning protocol. Scanning began with the occlusal surfaces, then used a wiggling motion across the dental arch to capture interproximal regions, and finished with buccal and palatal surfaces. This protocol is reported in the literature to yield high trueness and precision in intraoral digital impressions [17]. Every scanner, shade, and illuminance combination was scanned following the OWBP protocol, which served as a safeguard against systematic bias. To minimize operator-related variability, all scans were performed by a single experienced prosthodontist with more than five years of intraoral scanning practice. The scanning path and its starting point were standardized and maintained throughout all experimental conditions to minimize trajectory-related deviation [18].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDependent and Independent Variables\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAccuracy was evaluated using the mean absolute linear deviation (\u0026Delta;mean, \u0026micro;m), representing the average difference between each intraoral scanner\u0026rsquo;s distance measurements and the MEDIT T500 reference values. Four inter-landmark distances were recorded: AB (\u0026asymp;20.908 mm), BC (\u0026asymp;45.425 mm), CD (\u0026asymp;21.091 mm), and AD (\u0026asymp;27.394 mm). Since the raw data were collected in millimeters, they were converted to micrometers (\u0026times;1000) to facilitate interpretation and comparison. The absolute deviation for each distance was calculated as \u0026Delta;\u0026thinsp;=\u0026thinsp;|dIOS \u0026minus; dref|, where dIOS is the distance measured by the intraoral scanner and dref is the reference value. The mean across the four distances (\u0026Delta;mean) was computed as \u0026Delta;mean\u0026thinsp;=\u0026thinsp;(\u0026Delta;AB\u0026thinsp;+\u0026thinsp;\u0026Delta;BC\u0026thinsp;+\u0026thinsp;\u0026Delta;CD\u0026thinsp;+\u0026thinsp;\u0026Delta;AD)\u0026thinsp;/\u0026thinsp;4. Clinical acceptability was assessed against the 120\u0026thinsp;\u0026micro;m threshold, as defined by ISO 20896-1:2019 (an international standard for dental accuracy), and consistent with the criterion proposed for indirect dental restorations [19]. Raw distance deviations for each region (AB, BC, CD, and DA) are available in the Supplementary Tables. For the main statistical analysis, a combined deviation metric (\u0026Delta;mean) was used as the mean of the four regional deviations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBefore inferential analysis, normality of \u0026Delta;mean distributions was examined in each of the 24 experimental cells. Normality was assessed using the Shapiro\u0026ndash;Wilk test, supported by visual inspection of P-P and Q-Q plots. The assumption of homogeneity of variances was evaluated using Levene\u0026rsquo;s test. As all assumptions were satisfied, parametric tests were applied throughout the analysis.\u003c/p\u003e\n\u003cp\u003eA three-way ANOVA (Type III sum of squares) was performed. Scanner type, tooth shade, and illuminance were fixed factors. The statistical evaluation examined the main effects of each factor and their two-way and three-way interactions. Effect sizes were expressed as partial eta-squared (\u0026eta;\u003csup\u003e2\u003c/sup\u003ep), with conventional thresholds used to interpret magnitude (small (0.01\u0026ndash;0.06), medium (0.06\u0026ndash;0.14), and large (\u0026ge;0.14)). Significant main effects were followed up with Tukey\u0026apos;s HSD post hoc test to pinpoint group-level differences. Where interactions were significant, the analysis proceeded to simple effects, and a Bonferroni correction was applied to pairwise comparisons to control the familywise error rate.\u003c/p\u003e\n\u003cp\u003eMeasurement reliability was evaluated using the intraclass correlation coefficient (ICC; two-way mixed model, absolute agreement). A subset of 50 measurements was independently re-evaluated by a second examiner blinded to the primary examiner\u0026apos;s results, and re-measured by the primary examiner after a two-week interval. Inter-examiner and intra-examiner ICC values were calculated to evaluate consistency.\u003c/p\u003e\n\u003cp\u003eAmong the computed statistics, CV% (expressed as [SD/mean] \u0026times; 100) was used to assess repeatability. CV% values were calculated from four distance measurements across 10 scans per condition, and the mean CV% was used as the repeatability indicator. \u003c/p\u003e\n\u003cp\u003eSample size was determined via a priori power analysis (G*Power 3.1), assuming a large effect size (Cohen\u0026apos;s f = 0.40; \u0026eta;\u003csup\u003e2\u003c/sup\u003ep \u0026asymp; 0.14), consistent with previous studies. At \u0026alpha; = 0.05 and power = 0.95, a minimum of n = 6 per cell (N = 144) was needed. The chosen sample of n = 10 per cell (N = 240) gave a substantial safety margin above this minimum.\u003c/p\u003e\n\u003cp\u003eAll hypothesis tests were two-tailed (\u0026alpha; = 0.05). Statistical analyses were performed in SPSS Version 27 (IBM Corp., Armonk, NY, USA); power analyses in G*Power 3 [20].\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 24 experimental conditions arose from crossing three scanners with two tooth shades and four illuminance levels. For each condition, measurement deviations (\u0026Delta;mean, \u0026micro;m) of the ITERO Element 5D, SIRONA CEREC AC Omnicam, and SHINING Aoralscan 3 were evaluated relative to the MEDIT T500 reference scanner, with testing carried out under shades A1 and A4 at illuminance levels L100, L500, L1000, and L5000. All values are reported in micrometers (\u0026micro;m) and summarised in Table 1. Mean values above the 120 \u0026micro;m clinical threshold are marked by \u0026dagger;. Figure 2 shows the distribution of trueness values across conditions.\u003c/p\u003e\n\u003cp\u003eITERO Element 5D demonstrated the highest trueness among the three scanners, with a mean deviation of 85.6 \u0026plusmn; 32.0 \u0026micro;m (95% CI: 78.6\u0026ndash;92.6 \u0026micro;m). SIRONA CEREC AC Omnicam occupied an intermediate position with a mean deviation of 107.7 \u0026plusmn; 32.9 \u0026mu;m (95% CI: 100.4\u0026ndash;115.0 \u0026mu;m). SHINING Aoralscan 3 exhibited the lowest trueness and the highest mean deviation among the three scanners (122.8 \u0026plusmn; 33.4 \u0026mu;m; 95% CI: 115.4\u0026ndash;130.3 \u0026mu;m). Any mean value crossing the 120 \u0026mu;m clinical acceptance threshold is indicated by \u0026dagger;. The difference between tooth shades A1 (107.3 \u0026plusmn; 35.4 \u0026micro;m; 95% CI: 100.9\u0026ndash;113.7 \u0026micro;m) and A4 (103.5 \u0026plusmn; 36.8 \u0026micro;m; 95% CI: 96.8\u0026ndash;110.1 \u0026micro;m) was not significant. The only significant difference in illuminance was between L1000 and L5000 (post hoc, p = 0.038). For SHINING Aoralscan 3 under shade A1, threshold violations occurred at L100 (146.8 \u0026micro;m), L1000 (139.0 \u0026micro;m), and L5000 (121.8 \u0026micro;m).\u003c/p\u003e\n\u003cp\u003eA three-way ANOVA assessed the effects of scanner type, tooth shade, and illuminance level on trueness. The model explained 41.8% of the variance, as shown in Table 2.\u003c/p\u003e\n\u003cp\u003eScanner type significantly affected trueness outcomes (F(2, 216) = 33.536, p \u0026lt; 0.001, \u0026eta;\u003csup\u003e2\u003c/sup\u003ep = 0.237). Tooth shade did not have a significant effect (F(1, 216) = 1.049, p = 0.307, \u0026eta;\u003csup\u003e2\u003c/sup\u003ep=0.005). Illuminance was significant, though its effect size was small (F(3, 216) = 2.722, p = 0.045, \u0026eta;\u003csup\u003e2\u003c/sup\u003ep = 0.036), as shown in Table 2.\u003c/p\u003e\n\u003cp\u003eAll two-way and three-way interactions were statistically significant. The three-way interaction demonstrated that trueness depends on the combined effects of scanner type, tooth shade, and illuminance (F(6, 216) = 5.777, p \u0026lt; 0.001, \u0026eta;\u003csup\u003e2\u003c/sup\u003ep = 0.138).\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eTukey HSD post hoc testing confirmed that each scanner differed significantly in trueness. ITERO Element 5D had the highest trueness (85.6 \u0026plusmn; 32.0 \u0026micro;m), followed by SIRONA CEREC AC Omnicam (107.7 \u0026plusmn; 32.9 \u0026micro;m), and SHINING Aoralscan 3 (122.8 \u0026plusmn; 33.4 \u0026micro;m).\u003c/p\u003e\n\u003cp\u003eEach scanner was significantly different in trueness (ITERO vs SIRONA: 22.1 \u0026micro;m, p \u0026lt; 0.001; ITERO vs SHINING: 37.2 \u0026micro;m, p \u0026lt; 0.001; SIRONA vs SHINING: 15.2 \u0026micro;m, p = 0.003). ITERO Element 5D had the highest trueness, SIRONA CEREC AC Omnicam was intermediate, and SHINING Aoralscan 3 had the lowest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA significant difference among illuminance levels was observed only between L1000 and L5000 (L1000 = 114.0 \u0026micro;m, L5000 = 99.4 \u0026micro;m). All other pairwise comparisons were not significant.\u003c/p\u003e\n\u003cp\u003eTwo-way interactions were further examined to characterise the independent contributions of each factor pair before interpreting the three-way interaction.\u003c/p\u003e\n\u003cp\u003eThe interaction between scanner type and tooth shade was significant (F(2, 216) = 4.882, p = 0.008; \u0026eta;\u003csup\u003e2\u003c/sup\u003ep = 0.043), indicating scanner-dependent differences in how shade affected trueness. Estimated marginal means showed that A1 outperformed A4, with lower deviations for ITERO (80.0 vs 91.7 \u0026micro;m) and SHINING (130.6 vs 115.1 \u0026micro;m). However, SIRONA showed the opposite pattern \u0026mdash; its deviations were smaller under A4 than A1 (103.7 vs 111.7 \u0026micro;m). SHINING stood out as the only scanner for which the shade effect was statistically significant (F(1, 216) = 5.791, p = 0.017), with A1 breaching the 120 \u0026micro;m clinical limit (130.6 \u0026micro;m\u0026dagger;) and A4 remaining just below it (115.1 \u0026micro;m). Shade exerted no statistically significant influence on ITERO (F(1, 216) = 3.493, p = 0.063) or SIRONA (F(1, 216) = 1.530, p = 0.217), and neither scanner exceeded the clinical threshold under either shade condition.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Scanner \u0026times; Illuminance interaction (F(6, 216) = 4.018, p = 0.001; \u0026eta;\u003csup\u003e2\u003c/sup\u003ep = 0.100) indicated that illuminance affected the three scanners differently. Whether illuminance affected trueness depended on which scanner was examined. ITERO\u0026apos;s simple effect was significant (F(3, 216) = 2.881, p = 0.037), with estimated marginal means of 74.0, 86.0, 101.0, and 82.0 \u0026micro;m at L100 through L5000, respectively, none exceeding the clinical limit; only L100 and L1000 differed significantly (p = 0.028). SIRONA did not reach significance (F(3, 216) = 2.377, p = 0.071), and pairwise contrasts were uniformly non-significant, although the L1000 mean of 119.0 \u0026micro;m hovered just under the 120 \u0026micro;m threshold. SHINING\u0026apos;s response to illuminance was both statistically strong (F(3, 216) = 5.499, p = 0.001) and clinically meaningful, its means spanning 37.0 \u0026micro;m from a low of 104.0 \u0026micro;m at L5000 to a high of 141.0 \u0026micro;m at L100 (\u0026dagger;). The contrast between L100 and L5000 was significant (p \u0026lt; 0.001), as L100 exceeded the clinical threshold.\u003c/p\u003e\n\u003cp\u003eDifferences between shade\u0026ndash;illuminance combinations were captured by a significant interaction effect (F(3, 216) = 3.492, p = 0.017; \u0026eta;\u0026sup2;p = 0.046). When illuminance was low, measurements for A1 and A4 were largely equivalent (L100: 104.0 vs 105.0 \u0026micro;m; L500: 98.0 vs 109.0 \u0026micro;m), and a similar degree of agreement was observed at L1000 (116.0 vs 112.0 \u0026micro;m). At L5000, A4 registered 23.0 \u0026micro;m lower than A1 (88.0 vs 111.0 \u0026micro;m), a divergence absent at lower illuminance levels and consistent with a darker-shade benefit that emerges only under very high ambient light. From a clinical standpoint, the A1 measurement at L1000 (116.0 \u0026micro;m) approached the 120 \u0026micro;m threshold, whereas the A4 reading at L5000 (88.0 \u0026micro;m) remained well within an acceptable range.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe three-way interaction (Scanner \u0026times; Shade \u0026times; Illuminance) was examined in detail by analysing the trueness profile of each scanner under A1 and A4 conditions across all four illuminance levels (Table 1). Mean values exceeding the 120 \u0026micro;m clinical acceptance threshold are indicated by \u0026dagger;.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Under shade A1, ITERO Element 5D stayed below the clinical acceptance threshold across all four illuminance levels, confirming mean-level clinical acceptability throughout the full illuminance range. The simple effect of illuminance within ITERO/A1 reached statistical significance (F(3, 216) = 5.694, p = 0.001). Deviations rose progressively from L100 (55.2 \u0026micro;m) to L500 (69.2 \u0026micro;m), L1000 (88.8 \u0026micro;m), and L5000 (105.0 \u0026micro;m), representing a 49.8 \u0026micro;m absolute increase across the range, yet all values remained well within the 120 \u0026micro;m clinical limit. L5000 differed significantly from both L100 (p = 0.001) and L500 (p = 0.037), while all other pairwise comparisons fell short of significance (all p \u0026gt; 0.05). Despite every A1 deviation staying below the clinical threshold, the significant rise at L5000 relative to lower illuminance levels suggests that very high ambient light reduces ITERO trueness for lighter tooth shades, albeit without entering a clinically unacceptable range.\u003c/p\u003e\n\u003cp\u003eITERO under A4 yielded a markedly different pattern. The illuminance effect within this subgroup was significant (F(3, 216) = 6.419, p \u0026lt; 0.001). At L100, the deviation was 93.5 \u0026micro;m. At L500 it rose to 102.0 \u0026micro;m, and at L1000 it reached 112.3 \u0026micro;m \u0026mdash; all within the acceptable range. L5000 broke this trend entirely, bringing the deviation down to 58.9 \u0026micro;m. This drop was significant relative to L100 (p = 0.048), L500 (p = 0.006), and L1000 (p \u0026lt; 0.001), meaning 5000 lux genuinely improved trueness for this shade. The A1 vs A4 difference across ITERO as a whole did not reach significance (p = 0.063), but this masks an important point: the two shades responded to illuminance in opposite directions. L5000 was the worst condition for A1 and the best for A4. That reversal is the most clinically relevant finding this device produced.\u003c/p\u003e\n\u003cp\u003eSIRONA CEREC AC Omnicam showed relatively stable trueness values under shade A1 across the tested illuminance levels. The measured deviations were 110.0 \u0026micro;m at L100, 110.5 \u0026micro;m at L500, 120.8 \u0026micro;m at L1000, and 105.5 \u0026micro;m at L5000, corresponding to an overall range of 15.3 \u0026micro;m across the full illuminance spectrum. Among these conditions, L1000 was the only level at which the clinical threshold was exceeded, with a mean deviation of 120.8 \u0026micro;m.\u003c/p\u003e\n\u003cp\u003eThe effect of illuminance within the SIRONA/A1 condition was not statistically significant (F(3, 216) = 0.497, p = 0.685), and all pairwise comparisons returned p = 1.000. The presence of a threshold violation despite the absence of statistically significant pairwise differences can be explained by the limited variability between conditions. Specifically, the relatively narrow range of 15.3 \u0026micro;m provides little separation between illuminance levels, reducing the ability of pairwise statistical contrasts to detect differences. For this reason, the clinical relevance of the L1000 finding should be considered independently of the p-value.\u003c/p\u003e\n\u003cp\u003eWithin the SIRONA system, the illuminance effect under shade A4 reached statistical significance (F(3, 216) = 3.695, p = 0.013), although none of the individual pairwise comparisons were significant. At lower illuminance levels, deviations remained relatively low, measuring 87.5 \u0026micro;m at L100 and 89.5 \u0026micro;m at L500. At higher illuminance levels, the values increased to 117.8 \u0026micro;m at L1000 and 120.0 \u0026micro;m at L5000, approaching but not exceeding the 120 \u0026micro;m threshold. Overall, the increase of 32.5 \u0026micro;m from L100 to L5000 represents a clinically notable change, even though pairwise statistical testing did not reveal significant contrasts. The global comparison between shades within the SIRONA system was not statistically significant (p = 0.217). Nevertheless, at lower illuminance levels\u0026mdash;particularly L100 and L500\u0026mdash;shade A4 demonstrated a clinically meaningful performance advantage.\u003c/p\u003e\n\u003cp\u003eAmong all devices tested, SHINING Aoralscan 3 generated the most clinically critical findings under shade A1. Threshold violations were recorded at three of the four illuminance levels: L100 (146.8 \u0026micro;m), L1000 (139.0 \u0026micro;m), and L5000 (121.8 \u0026micro;m), with only L500 (115.0 \u0026micro;m) falling within the acceptable range. The illuminance effect within SHINING/A1 did not reach statistical significance (F(3, 216) = 2.602, p = 0.053), missing the \u0026alpha; = 0.05 cutoff by a narrow margin. Pairwise comparisons similarly returned no significant contrasts (all p \u0026gt; 0.05; minimum p = 0.089 for L100 vs L500). These non-significant results should not be interpreted as evidence of acceptable performance. Three of the four illuminance levels exceeded the clinical threshold, and the minimum individual acceptance rate reached only 10% at L1000. In this context, statistical non-significance reflects the similarity among clinically unacceptable values rather than any genuine equivalence across acceptable ones.\u003c/p\u003e\n\u003cp\u003eShade A4 brought a clinically meaningful improvement. A highly significant illuminance effect was found within SHINING/A4 (F(3, 216) = 6.897, p \u0026lt; 0.001). Deviations at L1000 (105.5 \u0026micro;m) and L5000 (85.5 \u0026micro;m) fell comfortably below the threshold, whereas L100 (134.5 \u0026micro;m) and L500 (134.8 \u0026micro;m) continued to exceed it.\u003c/p\u003e\n\u003cp\u003eThe most striking pairwise differences under A4 were between L5000 and L100 (p = 0.001) and between L5000 and L500 (p = 0.001), confirming that the clinical benefit of shade A4 for SHINING is concentrated at high illuminance levels. The improvement from A1 to A4 was statistically significant (p = 0.017). The reduction from 121.8 \u0026micro;m under A1 to 85.5 \u0026micro;m under A4 at L5000 represents a notable improvement.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRepeatability and Measurement Reliability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRepeatability was evaluated using the coefficient of variation (CV%) calculated for each scanner\u0026ndash;shade\u0026ndash;illuminance combination. Across all 24 experimental conditions, CV% values ranged from 0.13% to 0.33%, with an overall mean of 0.25%, indicating excellent repeatability for all combinations. At the device level, mean CV% values were highly consistent across the three scanners, ranging from 0.24% to 0.26%.\u003c/p\u003e\n\u003cp\u003eThese findings indicate that the substantial differences in trueness between devices are more likely attributable to systematic scanner-specific deviations than to differences in measurement precision, as all three scanners exhibited comparable levels of repeatability. Of particular note, SHINING Aoralscan 3 achieved CV% values comparable to those of ITERO despite producing considerably higher mean deviations, revealing that precision and trueness are distinct as performance properties.\u003c/p\u003e\n\u003cp\u003eInter-examiner ICC values ranged from 0.952 to 0.975, and intra-examiner ICC values ranged from 0.971 to 0.980, both indicating excellent reliability (ICC \u0026gt; 0.90).\u003c/p\u003e\n\u003cp\u003eTo complement the three-way ANOVA, the percentage of individual measurements below the 120 \u0026micro;m clinical threshold was calculated for each scanner\u0026ndash;shade\u0026ndash;illuminance combination. This provides clinical reliability data at the individual measurement level beyond group means (Table 1).\u003c/p\u003e\n\u003cp\u003eAcross scanners, ITERO Element 5D demonstrated the highest individual-measurement reliability, with 68 of 80 measurements (85.0%) falling below the clinical threshold. SIRONA CEREC AC Omnicam achieved moderate reliability (55/80; 68.8%), while SHINING Aoralscan 3 produced the lowest device-level acceptance rate (37/80; 46.3%).\u003c/p\u003e\n\u003cp\u003eSix conditions achieved 100% individual acceptance: ITERO/A1/L100, ITERO/A1/L500, ITERO/A4/L100, ITERO/A4/L5000, SIRONA/A4/L100, and SHINING/A4/L5000.\u003c/p\u003e\n\u003cp\u003eThe most clinically critical finding was identified for SHINING/A1/L1000, in which only one measurement (10%) fell below the clinical threshold, while nine measurements (90%) exceeded 120 \u0026micro;m. This combination represents the highest clinical risk condition identified in the present study and is considered unsuitable for clinical use.\u003c/p\u003e\n\u003cp\u003eSHINING Aoralscan 3 demonstrated markedly shade-dependent individual acceptance rates: 32.5% under A1 versus 60.0% under A4, with the highest performance at A4/L5000 (100% individual acceptance).\u003c/p\u003e\n\u003cp\u003eAn analysis of individual-measurement acceptance rates substantially complements the group-means delta table. For example, ITERO/A4/L500 yielded a mean deviation of 102.0 \u0026micro;m, which falls below the 120 \u0026micro;m threshold; however, the individual acceptance rate for this condition was only 60%, indicating that 4 of 10 measurements exceeded the clinical limit despite a clinically acceptable group mean. This finding reveals the limitations of group-mean-based assessment alone and supports reporting both mean values and individual-measurement distributions in intraoral scanner trueness research.\u003c/p\u003e\n\u003cp\u003eITERO was the only scanner to maintain mean-level clinical acceptability across all eight shade\u0026ndash;illuminance combinations, establishing it as the most clinically reliable device in this study.\u003c/p\u003e\n\u003cp\u003eSIRONA CEREC AC Omnicam exceeded the clinical threshold only at A1/L1000 (120.8 \u0026micro;m\u0026dagger;); all other conditions were within the 120 \u0026micro;m limit, including A4/L5000, which met but did not exceed the threshold.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis in vitro study examined the combined effects of scanner type, tooth shade, and ambient illuminance on intraoral scanner trueness using a full-factorial three-way design. Among the three factors, scanner type emerged as the dominant source of variance (η\u003csup\u003e2\u003c/sup\u003ep\u0026thinsp;=\u0026thinsp;0.237). Although illuminance reached statistical significance, its effect size was small (η\u003csup\u003e2\u003c/sup\u003ep\u0026thinsp;=\u0026thinsp;0.036), suggesting that its influence on trueness should be interpreted in the context of device and shade characteristics.\u003c/p\u003e \u003cp\u003eThe Shade \u0026times; Illuminance interaction was significant (η\u003csup\u003e2\u003c/sup\u003ep\u0026thinsp;=\u0026thinsp;0.046), showing that tooth shade and illuminance did not act independently on trueness. The three-way interaction (η\u003csup\u003e2\u003c/sup\u003ep\u0026thinsp;=\u0026thinsp;0.138) further showed that the combined shade\u0026ndash;illuminance effect varied across scanner types. In other words, illuminance may not be a stand-alone predictor. Its impact on trueness depends on both the scanner type and tooth shade.\u003c/p\u003e \u003cp\u003eAt the clinical level, individual-measurement analysis revealed that group-mean deviations below the 120 \u0026micro;m threshold did not necessarily ensure clinically acceptable individual outcomes. In addition, no single illuminance level proved optimal across all device\u0026ndash;shade combinations.\u003c/p\u003e \u003cp\u003eDarker tooth shades altered the optical reflectivity and light-scattering properties of the scanned surface, affecting image acquisition and surface reconstruction. Previous reports have demonstrated an inverse correlation between the L* value of scanned materials and scanner trueness. Our data extend this relationship by showing that shade-related trueness loss is further modulated by both illuminance level and scanner type. Inter-device differences were consistent with the underlying technologies [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. ITERO Element 5D uses confocal imaging, SIRONA CEREC Omnicam uses triangulation projection, and SHINING Aoralscan 3 uses structured light. Each system shows different sensitivity to surface optical properties and ambient photon flux [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Differences in stitching algorithms and surface registration may also contribute to full-arch deviations [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe superior performance of ITERO across conditions was consistent with previous reports showing device-dependent differences in scanning accuracy under varying lighting conditions [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Lower ambient light has been associated with greater accuracy, which aligns with our A1 findings [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. However, this pattern did not apply to darker shades. For A4, ITERO performed best at L5000 and worst at L1000 \u0026mdash; a reversal that would not be detectable in single-shade study designs [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The combined effect of ambient and internal scanner light has been shown to influence accuracy differently across devices [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The higher Δmean values observed in this study relative to surface-based 3D RMS studies reflect the nature of landmark distance deviation as a measure of total geometric error across the full arch [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA systematic review has shown that ambient light affects scanner accuracy in a device-dependent manner [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. In addition, both illuminance level and colour temperature have been reported to influence intraoral scanning trueness, with optimal settings varying across systems [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Our results further demonstrate that illuminance effects cannot be interpreted independently. Instead, they can be evaluated within the joint framework of scanner type and tooth shade. In this context, the observed higher-order interaction structure may help explain discrepancies between previous studies, particularly those that evaluated lighting conditions without incorporating shade-related variation.\u003c/p\u003e \u003cp\u003eNo single illuminance level was optimal for all device\u0026ndash;shade combinations, highlighting the importance of examining factor interactions, since important differences may be missed when only main effects are considered [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA shade-dependent crossover pattern was observed with ITERO Element 5D. Under A1, trueness declined progressively as illuminance increased from L100 to L5000, yet all values remained below the clinical threshold. Conversely, under A4 conditions, the pattern reversed. The highest accuracy was achieved at L5000 (58.9 \u0026micro;m; 100% individual acceptance), while intermediate illuminance levels showed poorer performance. This indicates a non-monotonic response specific to 5000 lux. This behaviour may be explained by the confocal imaging principle of ITERO. Lighter shades tend to produce greater specular reflection under high illuminance, whereas darker shades may benefit from increased photon flux [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Prior studies identified optimal accuracy at 500 lux for a single scanner [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] and at 100 lux for the confocal Element 5D, consistent with our A1 findings [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The shade-related inversion observed under A4 has not been previously reported and represents a clinically relevant pattern that single-shade study designs cannot detect [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSHINING Aoralscan 3 exhibited the most pronounced shade-dependent trueness profile. Under A1 conditions, three of four illuminance levels exceeded the clinical threshold, with individual acceptance as low as 10% at L1000. Under A4 conditions, performance improved markedly at higher illuminance levels, reaching 100% individual acceptance at L5000. This pattern aligned with the previously reported inverse relationship between L* value and scanner trueness, whereby lighter shades generate greater surface reflection and increase the probability of image acquisition errors [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. However, darker shading did not uniformly improve performance. Threshold violations persisted at L100 and L500 under A4, indicating a non-monotonic interaction between shade and illuminance for this device. The 120 \u0026micro;m threshold, originally established for cement film thickness, can reveal failures at the individual level that group-mean reporting alone cannot capture [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Previous studies have reported that tooth shade affects accuracy across lighting conditions [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. However, the three-way interaction structure identified here revealed condition-specific failure patterns that single- or two-factor designs cannot detect.\u003c/p\u003e \u003cp\u003eThe absence of a significant main effect for tooth shade may appear to contradict the pronounced shade-related differences observed at the device level. This apparent inconsistency reflects a masking effect in which opposing directional changes across scanners were cancelled at the aggregated main-effect level. Crucially, tooth shade in this study was not a passive covariate but an experimentally manipulated factor: the same physical model was recoloured from A1 to A4 under controlled spectrophotometric verification, enabling direct isolation of shade as an independent variable. The significant Shade \u0026times; Illuminance interaction (η\u003csup\u003e2\u003c/sup\u003ep\u0026thinsp;=\u0026thinsp;0.046) demonstrated that shade effects on trueness varied across illuminance levels, with the largest A1\u0026ndash;A4 divergence emerging at L5000. The three-way interaction further revealed that this pattern is scanner-dependent: under ITERO at 5000 lux, A4 trueness improved markedly while A1 trueness simultaneously declined, producing a crossover that suppressed the shade main effect when data were aggregated. Interpreting a non-significant main effect for shade as evidence of no clinically relevant shade influence when significant interaction terms are present, and underscores the necessity of full-factorial designs for detecting higher-order interaction structures.\u003c/p\u003e \u003cp\u003eSIRONA CEREC AC Omnicam demonstrated the most stable trueness profile across illuminance levels, consistent with device-dependent illuminance responses reported for triangulation-based systems, which may exhibit lower sensitivity to external photon flux than confocal-based devices [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Under A1, illuminance changes produced only marginal variation, yet L1000 was the sole condition exceeding the clinical threshold, and individual acceptance remained at or below 70% throughout, indicating borderline clinical reliability. Under A4, a shade-dependent crossover emerged at L5000 \u0026mdash; mirroring, in the opposite direction, the pattern observed for ITERO \u0026mdash; where A4 deviations rose to the threshold level while A1 deviations remained lower. Our A1 findings were partly consistent with earlier reports [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The markedly reduced individual acceptance at A4/L5000 (40%), despite a mean deviation at the threshold, confirms that illuminance tolerance profiles are both technology- and shade-dependent.\u003c/p\u003e \u003cp\u003ePrecision was uniformly high across all 24 conditions regardless of scanner, shade, or illuminance level (CV%: 0.13\u0026ndash;0.33%; mean: 0.25%), with negligible between-device differences (ITERO: 0.24%; SIRONA and SHINING: 0.26% each) [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. These findings indicated that the substantial trueness differences observed across scanner types and experimental conditions reflected systematic device-specific deviations rather than random measurement variability, consistent with the conceptual distinction between trueness and precision as defined by ISO 20896-1:2019 [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIntraoral scanners acquire multiple sequential images that are digitally stitched together to reconstruct the complete surface geometry. Although this approach enables rapid full-arch digitisation, small alignment deviations between consecutive images may accumulate along the scanning path, resulting in cumulative stitching errors [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. This phenomenon represents an inherent limitation of intraoral scanning systems and may partially explain the trueness deviations observed in the present study. Furthermore, high ambient illuminance may exacerbate stitching errors by reducing image contrast and signal-to-noise ratio during sequential frame acquisition, providing an additional mechanistic pathway through which illuminance influences scanning trueness [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe results have actionable implications for scanner-specific clinical protocols. When using ITERO Element 5D with lighter tooth shades, reducing ambient illuminance to the 100\u0026ndash;500 lux range optimises trueness: both L100 (55.2 \u0026micro;m) and L500 (69.2 \u0026micro;m) achieved 100% individual acceptance, making either condition suitable for routine clinical use. At higher illuminance levels, individual reliability progressively declined \u0026mdash; to 90% at L1000 and 70% at L5000 \u0026mdash; indicating that even mean-acceptable conditions carried a non-trivial proportion of out-of-threshold measurements as ambient light increased. The shade-dependent crossover pattern observed for this device dictates a markedly different approach for darker shades: under A4, 5000 lux yielded the most favourable outcome (58.9 \u0026micro;m; 100% individual acceptance), and L100 was also clinically acceptable (93.5 \u0026micro;m; 100% individual acceptance). The intermediate conditions of L500 and L1000 should be avoided for A4 scanning, as both yielded only 60% individual acceptance despite sub-threshold group means of 102.0 and 112.3 \u0026micro;m \u0026mdash; a finding that group-mean analysis alone would not reveal.\u003c/p\u003e \u003cp\u003eAmong the three devices, SHINING Aoralscan 3 showed the most restrictive clinical profile. For A1-range shades, three of the four illuminance levels tested produced mean deviations above the clinical threshold \u0026mdash; L100 (146.8 \u0026micro;m; 30% individual acceptance), L1000 (139.0 \u0026micro;m; 10% individual acceptance), and L5000 (121.8 \u0026micro;m; 40% individual acceptance) \u0026mdash; and should be considered unsuitable for clinical use. Although L500 remained below the mean-level threshold (115.0 \u0026micro;m), its individual acceptance rate of only 50% means that one in two measurements still exceeded the clinical limit. This failure rate warrants considerable caution. Clinicians using this scanner with A1-range shades should prefer L500 where feasible, while acknowledging that no tested condition achieved reliably acceptable individual-level performance. For A4-range shades, the lower illuminance levels remained problematic: L100 (134.5 \u0026micro;m; 30% individual acceptance) and L500 (134.8 \u0026micro;m; 40% individual acceptance) both exceeded the threshold. Trueness improved meaningfully from L1000 onward (105.5 \u0026micro;m; 70% individual acceptance), reaching its best performance at L5000 (85.5 \u0026micro;m; 100% individual acceptance). Darker shading, therefore, does not guarantee acceptable results with this scanner unless combined with high ambient illuminance. SIRONA CEREC AC Omnicam demonstrated generally acceptable performance with one notable exception: A1/L1000 (120.8 \u0026micro;m; 50% individual acceptance) exceeded the mean-level threshold and should be avoided. Under all remaining A1 conditions, individual acceptance rates were consistently at or below 70%, suggesting that borderline reliability persists even when group means remain within the acceptable range. For A4, performance was more favourable at lower illuminance levels \u0026mdash; L100 (87.5 \u0026micro;m; 100% individual acceptance) and L500 (89.5 \u0026micro;m; 80%) both performed well \u0026mdash; but individual acceptance declined to 70% at L1000 and to only 40% at L5000, where the mean deviation reached exactly 120.0 \u0026micro;m. Both higher illuminance conditions warrant clinical caution for this scanner, even in the absence of a mean-level threshold violation at L5000.\u003c/p\u003e \u003cp\u003eThe full-factorial three-way design used in this study offers a methodological advantage over the single- and two-factor approaches common in the literature [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. By simultaneously manipulating scanner, shade, and illuminance across all combinations, the design enabled detection of interaction effects that would be invisible in single-variable protocols. This is particularly relevant, as the highest-risk condition\u0026mdash;SHINING/A1/L1000 with only 10% individual acceptance\u0026mdash;could not have been predicted based on the lighting effect alone. Only one significant pairwise difference between illuminance levels was identified, and this analysis provided no information on the direction or clinical magnitude of effects at the scanner \u0026times; shade level. The robustness of the observed interaction effects is supported by their large effect sizes and consistent patterns across conditions.\u003c/p\u003e \u003cp\u003eSeveral limitations warrant acknowledgement. The phantom model design, while enabling precise environmental control, precludes direct extrapolation to the clinical intraoral environment, where factors such as saliva, soft tissue reflections, patient movement, and operator skill introduce additional variance [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Only two shades from the VITA classical scale were evaluated, and the full chromatic range may yield different scanner-specific interaction patterns. Given the increasing prevalence of tooth whitening in clinical practice, future studies should prioritise the inclusion of high-luminosity bleached shades (e.g., B1, OM1), which represent particularly challenging conditions for structured-light and confocal systems due to their elevated specular reflectance. Colour temperature of the ambient light source was varied within the 3500\u0026ndash;6500 K range to simulate natural daylight conditions; the independent and joint effects of specific colour temperature levels and illuminance were not systematically isolated in the present design and represent an important variable for future study [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The repeatability metric, CV% of landmark distances, is not directly comparable to full-surface 3D RMS deviation used in many published studies, and cross-study quantitative comparisons must therefore be made with caution. Finally, only one model geometry was scanned, and the influence of preparation design, arch complexity, and scan span on the observed interactions remains to be investigated.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThese findings indicate that the clinical performance of an intraoral scanner cannot be characterised solely by device specifications. Identical ambient conditions yielded markedly different outcomes \u0026mdash; ranging from complete individual acceptance to only 30% acceptance \u0026mdash; within the same lux level. Future research should incorporate in vivo designs across diverse patient populations and extend the shade range to include the full VITA classical and 3D-Master scales. Studies systematically comparing confocal, triangulation, and structured-light technologies under matched conditions would further clarify the mechanistic basis of the technology-dependent illuminance responses observed here [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. The integration of individual-measurement-level acceptance analysis alongside group means should become standard practice in intraoral scanner trueness research, as group means may mask clinically significant failure patterns at the individual level.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003eANOVA\u003c/strong\u003e: Analysis of Variance\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCI\u003c/strong\u003e: Confidence Interval\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCV%\u003c/strong\u003e: Coefficient of Variation (%)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHSD\u003c/strong\u003e: Honestly Significant Difference\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eICC\u003c/strong\u003e: Intraclass Correlation Coefficient\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIOS\u003c/strong\u003e: Intraoral Scanner\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eISO\u003c/strong\u003e: International Organization for Standardization\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLED\u003c/strong\u003e: Light-Emitting Diode\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOWBP\u003c/strong\u003e: Occlusal\u0026ndash;Wiggling\u0026ndash;Buccal\u0026ndash;Palatal\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRMS\u003c/strong\u003e: Root Mean Square\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSD\u003c/strong\u003e: Standard Deviation\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSEM\u003c/strong\u003e: Standard Error of the Mean\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026Delta;mean\u003c/strong\u003e: Mean Absolute Landmark Distance Deviation\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026eta;\u0026sup2;p\u003c/strong\u003e: Partial Eta-Squared\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank the Proofreading \u0026amp; Editing Office of the Dean for Research at Erciyes University for this manuscript\u0026apos;s copyediting and proofreading service.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eE.O. conceived and designed the study, performed the experiments, collected the data, and wrote the manuscript. O.O. conducted the statistical analyses and contributed to data interpretation. A.G. contributed to the study design, supervised the research, and critically revised the manuscript. All authors reviewed and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis in vitro study did not involve human participants or animals and therefore did not require ethics committee approval.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eM\u0026ouml;rmann WH. The evolution of CEREC system. J Am Dent Assoc. 2006;137(9 Suppl):7S\u0026ndash;13S.\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eBoeddinghaus M, Breloer ES, Rehmann P, W\u0026ouml;stmann B. Accuracy of single-tooth restorations based on intraoral digital and conventional impressions in patients. Clin Oral Investig. 2015;19:2027\u0026ndash;34.\u003c/li\u003e\n\u003cli\u003eDonovan TE, Chee WW. A review of contemporary impression materials and techniques. Dent Clin North Am. 2004;48(2):445\u0026ndash;70.\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003ePatzelt SB, Emmanouilidi A, Stampf S, Strub JR, Att W. Accuracy of full-arch scans using intraoral scanners. Clin Oral Investig. 2014;18:1687\u0026ndash;94.\u003c/li\u003e\n\u003cli\u003eRichert R, Goujat A, Venet L, Viguie G, Viennot S, Robinson P, Farges JC, Fages M, Ducret M. Intraoral scanner technologies: a review to make a successful impression. 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Influence of ambient temperature changes on intraoral scanning accuracy. J Prosthet Dent. 2023;130:755\u0026ndash;60.\u003c/li\u003e\n\u003cli\u003eTurkish Standards Institution. TS EN 12464-1: Light and lighting \u0026ndash; Lighting of workplaces \u0026ndash; Part 1: Indoor workplaces. Ankara: TSE; 2011. Available from: https://www.tse.org.tr. Accessed 1 Apr 2026.\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eInternational Organization for Standardization. Dentistry \u0026ndash; Digital impression devices \u0026ndash; Part 1: Methods for assessing accuracy. ISO 20896-1. Geneva: ISO; 2019. Available from: https://www.iso.org/standard/69121.html. Accessed 1 Apr 2026.\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eYahya MA, Selleus M, Hadi DJ, Braian M, Larsson C. The effect of different scanning protocols on precision and trueness of intraoral scanning: a pilot trial. 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Int J Oral Implantol (Berl). 2021;14(2):157\u0026ndash;79.\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eMangano F, Veronesi G, Hauschild U, Mijiritsky E, Mangano C. Trueness and precision of four intraoral scanners in oral implantology: a comparative in vitro study. PLoS One. 2016;11:e0163107.\u003c/li\u003e\n\u003cli\u003eCamcı H, Salmanpour F. Effect of saliva isolation and intraoral light levels on performance of intraoral scanners. Am J Orthod Dentofacial Orthop. 2020;158:759\u0026ndash;66.\u003c/li\u003e\n\u003cli\u003eRevilla-Le\u0026oacute;n M, Subramanian SG, \u0026Ouml;zcan M, Krishnamurthy VR. Clinical study of the influence of ambient light scanning conditions on the accuracy (trueness and precision) of an intraoral scanner. J Prosthodont. 2020;29:107\u0026ndash;13.\u003c/li\u003e\n\u003cli\u003eKoseoglu M, Kahramanoglu E, Akin H. Evaluating the effect of ambient and scanning lights on the trueness of the intraoral scanner. J Prosthodont. 2021;30:811\u0026ndash;16.\u003c/li\u003e\n\u003cli\u003eMa Y, Guo YQ, Saleh MQ, Yu H. Influence of ambient light conditions on intraoral scanning: a systematic review. J Prosthodont Res. 2024;68:237\u0026ndash;45.\u003c/li\u003e\n\u003cli\u003eKarakuzu M, \u0026Ouml;zt\u0026uuml;rk C, Karakuzu ZB, Zortuk M. The effects of different lighting conditions on the accuracy of intraoral scanning. J Adv Prosthodont. 2024;16:311\u0026ndash;18.\u003c/li\u003e\n\u003cli\u003eGuo Y, Ma Y, Wang Z, Yu H. Effects of ambient lighting conditions on the scanning accuracy and shade matching capability of intraoral scanners: an in vitro study. BMC Oral Health. 2025;25:1088.\u003c/li\u003e\n\u003cli\u003eZhou Y, Fu L, Zhang Z, Tang X. Effect of tooth color on the accuracy of intraoral complete arch scanning under different light conditions using a zirconia restoration model. J Prosthet Dent. 2024;131:145.e1\u0026ndash;145.e8.\u003c/li\u003e\n\u003cli\u003eOchoa-L\u0026oacute;pez G, Cascos R, Antonaya-Mart\u0026iacute;n JL, Revilla-Le\u0026oacute;n M, G\u0026oacute;mez-Polo M. Influence of ambient light conditions on the accuracy and scanning time of seven intraoral scanners in complete-arch implant scans. J Dent. 2022;121:104138.\u003c/li\u003e\n\u003cli\u003eArakida T, Kanazawa M, Iwaki M, Suzuki T, Minakuchi S. Evaluating the influence of ambient light on scanning trueness, precision, and time of intra oral scanner. J Prosthodont Res. 2018;62:324\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eWesemann C, Kienbaum H, Thun M, Spies BC, Beuer F, Bumann A. Does ambient light affect the accuracy and scanning time of intraoral scans? J Prosthet Dent. 2021;125:924\u0026ndash;31.\u003c/li\u003e\n\u003cli\u003ePiedra-Casc\u0026oacute;n W, Adhikari RR, \u0026Ouml;zcan M, Krishnamurthy VR, Revilla-Le\u0026oacute;n M, Gallas-Torreira M. Accuracy assessment (trueness and precision) of a confocal based intraoral scanner under twelve different ambient lighting conditions. J Dent. 2023;134:104530.\u003c/li\u003e\n\u003cli\u003eKernen F, Schlager S, Seidel Alvarez V, Mehrhof J, Vach K, Kohal R, Nelson K, Fl\u0026uuml;gge T. Accuracy of intraoral scans: an in vivo study of different scanning devices. J Prosthet Dent. 2022;128:1303\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eRevilla-Le\u0026oacute;n M, Jiang P, Sadeghpour M, Piedra-Casc\u0026oacute;n W, Zandinejad A, \u0026Ouml;zcan M, Krishnamurthy VR. Intraoral digital scans\u0026mdash;Part 1: Influence of ambient scanning light conditions on the accuracy (trueness and precision) of different intraoral scanners. J Prosthet Dent. 2020;124:372\u0026ndash;8.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1\u0026nbsp;\u003c/strong\u003eTrueness (\u0026Delta;mean, \u0026micro;m) and Individual Acceptance Rates (%) of Three Intraoral\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eScanners Across Tooth Shade and Ambient Illuminance Conditions\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScanner\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eShade\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIlluminance\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean (\u0026micro;m)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD (\u0026micro;m)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMin (\u0026micro;m)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMax (\u0026micro;m)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAcceptance\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScanner\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"8\" valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eITERO\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL100\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e55.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e15.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e35.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e75.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e90.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL500\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e69.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e15.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e40.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e92.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL1000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e88.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e26.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e42.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e135.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e90%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL5000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e105.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e28.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e52.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e150.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e70%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL100\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e93.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e23.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e40.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e120.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e80.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL500\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e102.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e38.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e52.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e155.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e60%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL1000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e112.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e24.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e75.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e147.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e60%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL5000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e58.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e26.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e105.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"8\" valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSIRONA\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL100\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e110.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e24.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e80.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e157.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e70%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e65.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL500\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e110.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e19.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e85.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e140.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e70%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL1000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e120.8\u0026dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e22.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e92.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e170.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e50%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL5000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e105.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e20.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e72.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e135.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e70%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL100\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e87.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e19.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e50.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e115.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e72.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL500\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e89.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e33.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e47.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e145.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e80%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL1000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e117.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e34.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e70.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e175.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e70%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL5000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e120.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e59.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e35.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e210.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e40%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"8\" valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSHINING\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL100\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e146.8\u0026dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e37.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e92.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e202.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e30%\u0026Dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e32.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL500\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e115.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e40.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e45.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e160.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e50%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL1000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e139.0\u0026dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e16.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e115.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e170.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e10%\u0026Dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL5000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e121.8\u0026dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e30.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e75.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e182.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e40%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL100\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e134.5\u0026dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e26.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e95.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e175.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e30%\u0026Dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e60.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL500\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e134.8\u0026dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e21.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e115.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e172.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e40%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL1000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e105.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e27.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e65.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e162.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e70%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL5000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e85.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e20.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e57.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e120.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 86px;\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eSD: standard deviation; \u0026Delta;mean: mean absolute deviation (\u0026micro;m); Min: minimum observed \u0026Delta;mean (\u0026micro;m); Max: maximum observed \u0026Delta;mean (\u0026micro;m); n = 10 per cell. \u0026dagger; mean exceeds 120 \u0026micro;m clinical acceptance threshold (ISO 20896-1:2019). \u0026Dagger; individual acceptance rate \u0026lt;40% (high clinical risk). Overall Mean (%): mean individual acceptance rate across all four illuminance levels per scanner\u0026ndash;shade combination.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e Three-way ANOVA results evaluating the effects of scanner type, tooth shade, and illuminance level on \u0026Delta;mean values\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"647\" class=\"fr-table-selection-hover\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 225px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSource\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e\u003cstrong\u003edf\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eF\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026eta;\u003c/strong\u003e\u003cstrong\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/strong\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEffect Size\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 225px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScanner\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e33.536\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e0.237\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003eLarge\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 225px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTooth Shade\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e1.049\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.307\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e0.005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003eNegligible\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 225px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIlluminance Level\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e2.722\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.045*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e0.036\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003eSmall\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 225px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScanner \u0026times; Shade\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e4.882\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.008*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e0.043\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003eSmall\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 225px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScanner \u0026times; Illuminance\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e4.018\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e0.100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003eMedium\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 225px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eShade \u0026times; Illuminance\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e3.492\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e0.017*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e0.046\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003eSmall\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 225px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScanner \u0026times; Shade \u0026times; Illuminance\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e5.777\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e0.138\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 87px;\"\u003e\n \u003cp\u003eMedium\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003edf: degrees of freedom, \u0026eta;\u003csup\u003e2\u003c/sup\u003ep: partial eta squared, effect size benchmarks: \u0026lt;0.01 negligible, 0.01\u0026ndash;0.06 small, 0.06\u0026ndash;0.14 medium, \u0026gt;0.14 large, *p \u0026lt; 0.05\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Ambient illuminance, Digital impression, Intraoral scanner, Repeatability, Trueness, Tooth shade","lastPublishedDoi":"10.21203/rs.3.rs-9329206/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9329206/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003cbr\u003e\nThe present study was designed to investigate the influence of tooth shade and ambient illuminance on the trueness and repeatability of three intraoral scanners and to determine whether these factors interact under controlled experimental conditions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003cbr\u003e\nA mandibular phantom model was scanned using three intraoral scanners: ITERO Element 5D, SIRONA CEREC AC Omnicam, and SHINING Aoralscan 3. Two tooth shades (A1 and A4) were evaluated under four ambient illuminance levels (100, 500, 1000, and 5000 lux). A full-factorial experimental design (three-way ANOVA) was employed, yielding 240 scans and 960 distance measurements. Reference values were obtained using a desktop scanner (MEDIT T500). Trueness was calculated as the mean deviation of landmark distances (Δmean, µm), with clinical acceptability defined as Δmean ≤ 120 µm. Effects were analyzed using a three-way ANOVA with post hoc comparisons.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003cbr\u003e\nOf the factors tested, scanner type had the strongest effect on trueness (η²p = 0.237), consistent with a large effect by conventional benchmarks. A three-way interaction was also detected among scanner type, tooth shade, and ambient illuminance (η²p = 0.138), indicating that the influence of tooth shade on trueness varied across scanner–illuminance combinations.\u003c/p\u003e\n\u003cp\u003eITERO demonstrated a shade-dependent crossover pattern, with trueness decreasing under A1 and improving under A4 at higher illuminance. SIRONA CEREC AC Omnicam showed intermediate trueness with relative illuminance stability. SHINING Aoralscan 3 exhibited the lowest trueness, with acceptance rates as low as 10% under A1 at L1000, rendering this condition clinically unsuitable. Repeatability remained high across all scanners (CV% \u0026lt; 0.33%).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003cbr\u003e\nScanner type was the primary determinant of trueness. Illuminance effects were device- and shade-dependent, and no single illuminance level was optimal. Clinically acceptable group means may mask clinically unacceptable individual measurements, underscoring the value of individual-level evaluation in accuracy assessments.\u003c/p\u003e","manuscriptTitle":"Tooth Shade and Ambient Illuminance Interact to Affect the Trueness and Repeatability of Intraoral Scanners: A Full-Factorial Experimental Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-24 00:44:26","doi":"10.21203/rs.3.rs-9329206/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-06T15:29:17+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-29T14:18:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"310576470127693640121631792933950081191","date":"2026-04-29T13:34:03+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-27T20:12:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"28818818347280222207928382523569632056","date":"2026-04-27T10:35:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"93612515972274436593440947800999840646","date":"2026-04-27T06:37:38+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-15T13:46:39+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-13T08:54:43+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-11T01:36:36+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-11T01:36:02+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2026-04-06T02:27:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"11d6d884-ed1a-4eeb-a50d-e289e1896b86","owner":[],"postedDate":"April 24th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-06T15:29:17+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-29T14:18:13+00:00","index":106,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-14T00:08:15+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-24 00:44:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9329206","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9329206","identity":"rs-9329206","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}