Synergistic effect of laser irradiation and remineralizing agents on surface microhardness of primary tooth enamel -An in-vitro study

Synergistic effect of laser irradiation and remineralizing agents on surface microhardness of primary tooth enamel -An in-vitro 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 Synergistic effect of laser irradiation and remineralizing agents on surface microhardness of primary tooth enamel -An in-vitro study Girish Babu KL, Kavyashree Gururaj Hebbar, Geeta Maruti Doddamani This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5727275/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 15 Apr, 2025 Read the published version in Lasers in Medical Science → Version 1 posted 9 You are reading this latest preprint version Abstract Purpose To evaluate the synergistic effect of erbium laser irradiation and remineralizing agents on the surface microhardness of primary tooth enamel. Methods A total of 380 primary molars were collected. Teeth were embedded in acrylic resin such that only their buccal surface were exposed. The initial surface microhardness (SMH) was measured and the teeth were allocated into 19 groups: Group-1-Positive control, Group-2-Negative control, Group-3-Er: YAG laser, Group-4- Er,Cr:YSGG laser, Group-5-Fluorovil®, Group-6-Fluor Protector® varnish, Group-MI Paste®, Group-8-MI Paste Plus®, Group-9-MI varnish®, Group-10-Er: YAG + Fluorovil®, Group-11-Er: YAG + Fluor Protector® varnish, Group-12-Er: YAG + MI Paste®, Group-13-Er: YAG + MI Paste Plus®, Group-14-Er: YAG + MI Varnish®, Group-15-Er,Cr:YSGG + Fluorovil®, Group-16-Er,Cr:YSGG + Fluor Protector® varnish, Group-17-Er,Cr:YSGG + MI Paste®, Group-18-Er,Cr:YSGG + MI Paste Plus® and Group-19-Er,Cr:YSGG + MI Varnish®. After the planned enamel surface treatments, a second SMH measurement was taken. The samples were then subjected to a demineralization-remineralization cycle, followed by a third SMH measurement. Results The highest SMH after the demineralization-remineralization cycle was recorded with the use of Er: YAG laser in combination with Fluor Protector® varnish (Group 11) (418.40 ± 4.17), while the lowest value was seen with the use of Er, Cr: YSGG laser alone (Group 4) (259 ± 15.53). Conclusion The results indicate that erbium laser irradiation, followed by the application of remineralizing agents, has a synergistic effect in increasing enamel SMH. This suggests the potential use of such treatments as a preventive measure for dental caries. Deciduous/primary teeth ·enamel erbium Laser surface microhardness Figures Figure 1 Figure 2 Figure 3 INTRODUCTION Lasers have revolutionized pediatric dentistry by providing a range of treatments for children, including caries prevention, detection, removal, cavity preparation, and the sealing of pits and fissures. Among these, erbium lasers, namely Er: YAG (wavelength of 2940 nm) and Er, Cr: YSGG (wavelength of 2780 nm), are particularly promising for use on mineralized dental tissues. While both lasers are effective and safe, they differ in wavelength, absorption, and ablation efficiency. The Er: YAG laser exhibits a threefold higher absorption coefficient compared to the Er, Cr: YSGG laser, resulting in deeper heat penetration into irradiated tissue or material for the latter, which produces a thicker indirectly heated zone. This excess heating can reduce ablation efficiency and increase charring compared to the Er: YAG laser [ 1 , 2 ]. Consequently, the Er: YAG laser is more efficient for enamel and dentin treatment due to its superior absorption characteristics [ 1 – 3 ]. However, some studies have found that both types of erbium lasers comparably enhance enamel microhardness [ 4 – 6 ]. Early enamel lesions have the potential for remineralization, increasing their enamel surface resistance to further acid challenges, especially with enhanced remineralization treatments. The application of remineralizing agents, such as fluoride gels, varnishes, dentifrices, and casein phosphopeptide amorphous calcium phosphate (CPP-ACP) agents, increases the availability of calcium, phosphate, and fluoride ions in the oral environment. This enhances the remineralization process, reduces demineralization, and increases the surface microhardness (SMH) of enamel [ 7 ]. Contradictory reports exist regarding the cumulative effects of lasers and remineralizing agents on enamel. Some studies have shown positive results, while others have reported negative outcomes or no effect [ 4 – 6 , 8 – 12 ]. Additionally, most studies have focused on permanent teeth and primarily assessed mineral loss, fluoride content, and enamel surface topography following laser irradiation [ 9 , 13 ]. Furthermore, the impact of laser treatment on primary tooth enamel differs from that on permanent tooth enamel. There is also a lack of research evaluating the effects of erbium lasers in conjunction with remineralizing agents on primary tooth enamel. Therefore, the purpose of this study is to evaluate the synergistic effect of erbium laser irradiation and remineralizing agents on the surface microhardness of primary tooth enamel. METHODS Ethical Considerations The study followed a randomized, controlled, parallel in-vitro design and obtained approval from the Institutional Ethics Committee (IEC/HIMS/RR235). Throughout the research, adherence to established guidelines for reporting pre-clinical in-vitro studies on dental materials was maintained [ 14 ]. The study also aligned with the ethical principles outlined in the World Medical Association's Declaration of Helsinki and followed the CONSORT guidelines for study design (Fig. 1 ). Sample size calculation Based on the previous studies [ 5 , 6 ] the sample size estimation was performed at 5% alpha error (α = 0.05), with an effect size of 0.36 and the power of the study at 80% using G Power software (latest ver. 3.1.9.7; Heinrich-Heine- Universi-ta ̈t Du ̈sseldorf, Du ̈sseldorf, Germany). The estimation demonstrated that a minimum of 20 samples were in each group, thus the total samples consisted of 380. Teeth Sample Collection The sound human primary molars extracted from normal and healthy children 6 to 9 years visiting the department were collected. Parents or legal guardians received detailed information about the study's objectives, procedures, outcomes, and associated risks and benefits. After addressing their questions, written consent was obtained, and the children provided their assent. A total of 427 teeth were collected, and extracted for reasons such as orthodontic needs, over-retention, or pre-shedding mobility causing discomfort [ 6 ]. Selection Criteria for Teeth Only teeth without cracks, restorations, caries, fluorosis, abrasion, or other anomalies/imperfections were selected. Any teeth with caries, developmental defects, a history of pulpectomy, or damage during extraction were excluded, resulting in a final sample of 380 teeth [ 5 , 6 , 9 ]. Preparation of Teeth Samples Following extraction, the teeth were immediately placed in a 0.9% saline solution. Within 24 hours, they underwent cleaning to remove soft debris, calculus, and stains using scrapers and ultrasonic scalers. Subsequently, pumice was applied with a rubber cup under water cooling for polishing. The prepared teeth were then stored in dark glass containers containing a 1% thymol solution for disinfection over a week at room temperature and to keep the samples moist to avoid dehydration which leads to enamel brittleness. Afterward, thorough rinsing with tap water for 2 hours eliminated any remaining thymol residues. The roots of the teeth were separated from the crowns using a water-cooled high-speed diamond bur. Finally, all teeth were examined under 40X magnification to detect any surface defects or cracks [ 5 ]. Polyvinyl plastic cylinder tubes (Zhejiang Liutongplas tics Co., Ltd., China) were cut into equal rings with a 20 mm diameter and 8 mm depth with parallel and flat top and bottom sides to make samples suitable for the microhardness test. After that, each ring was filled with autopolymerizing acrylic resin (Acropars, Tehran, Iran), and the teeth were embedded in the center of the ring so that the buccal surface remained exposed and facing upward. To prepare the enamel surfaces, they were ground flat and polished under continuous water cooling. This polishing process involved using silicon carbide abrasive papers with varying grit sizes: 800, 1200, and 2000-grit. The goal was to achieve a flat and smooth enamel surface. Following, each specimen was rechecked to confirm the absence of any cracks or fractures under the digital microscope at 50x magnification [ 5 – 7 ]. Next, adhesive tapes measuring 3 × 3 mm² were placed on the enamel samples. The remaining surface was coated with two layers of nail varnish. After the nail varnish dried, the tapes were removed, and the samples were rinsed with deionized water. This standardized the enamel window surface to 3 × 3 mm² for all teeth. Each tooth sample was then coded with a marker, and a bur was placed in a high-speed handpiece. The samples were stored in deionized water until the planned procedure was carried out, which was carried out within one month [ 14 – 16 ] Measurement of Baseline Surface Micro-hardness (First SMH) The baseline SMH of the primary enamel was measured using a calibrated Vickers micro-hardness tester (Shimadzu HMV-2000/Shimadzu Corporation, Kyoto, Japan). SMH of each sample was assessed by making five indentations on enamel by applying 200g of load for 10 s. The indentations were strategically placed on the left upper, left lower, central, right upper, and right lower parts of the enamel samples. The value displayed on the machine was noted. The mean of the five values was calculated and recorded as the SMH of the respective sample [ 5 , 7 , 15 ]. The values were expressed in VHN. The baseline SMH of all the samples was measured to rule out any variations of enamel samples. SMH in all three groups was measured and found to have no statistically significant difference. Hence, changes in microhardness values after intervention would be attributed to the laser/ laser + remineralizing agent therapy. Randomization The 380 selected teeth were randomly assigned into 19 groups, with each group containing 20 teeth. The allocation was based on the type of enamel surface treatment. To ensure randomization, a block randomization technique was employed, using varying block sizes. An assistant, not directly involved in the study, provided a computer-generated sequence for this purpose. The allocation process was carried out using sealed envelopes, each with a unique serial number, which was opened just before applying the enamel surface treatment [ 17 ]. Intervention The selected teeth samples in the groups were subjected to enamel surface treatment as shown in table-1. After the enamel surface treatment, the SMH of enamel (second SMH) was measured using the Vickers micro-hardness tester as described earlier [ 5 , 7 , 15 ]. Demineralization-remineralization cycle [ 5 , 7 , 19 ] Following, all the teeth samples, except samples of group 1, were subjected to a demineralization-remineralization cycle simulating a high caries challenge.14 Each enamel sample was placed in a separate container and immersed in demineralizing solution (2 mM CaCl2, 2.2 mM NaH2PO4,0.05 M CH3COOH, 1 M KOH pH:4.5) for 6 h once a day, followed by rinsing with distilled and deionized water for 10 second and gentle drying with absorbent paper. Then the specimens were individually immersed in the remineralization solution (1.5 mM CaCl2, 0.9 mM NaH2PO4, and 0.15M KCL, pH:7.0) for the remaining 18 h of the day. All procedures were carried out at 370C. After, 5 days of the cycle, the samples were left in remineralization solution for 2 days, and the cycle was completed. The solutions were renewed every 3 days and changed daily. On the 8th day, all the samples were taken out of the solution and dried using blotting paper. Following, the samples were rinsed with saline for 10 seconds, and their SMH of enamel (Third SMH) was measured using a Vickers micro-hardness tester as described earlier. The demineralization and remineralization cycle model allowed the evaluation of changes on the outermost enamel layer during caries development. All treatments were performed by a single skillful and trained operator. The single-calibrated examiner assessed the SMH. Blinding The assessor of SMH and data analyzing statistician were blinded to the type of enamel surface treatments to prevent bias, while the operator performing the treatments could not be blinded due to the nature of the procedures. Statistical Analysis The data obtained was tabulated and subjected to statistical analysis. Statistical Package for Social Sciences [SPSS] for Windows Version 22.0 Released 2013. Armonk, NY: IBM Corp., was used to perform statistical analyses. Descriptive Statistics: Descriptive analysis includes expression of SMH in terms of Mean & SD for each group. Inferential Statistics: One-way ANOVA Test followed by Tukey's post hoc Test and Independent Student t-test was used to compare the mean SMH between groups. The level of significance was set at P < 0.05. RESULTS Mean Surface Microhardness (SMH) Values The mean SMH values for each group are presented in Table 2. Following the planned enamel surface treatment (B), an increase in SMH was observed across all groups (Group 3 to Group 19) compared to baseline values (A). The greatest increase in SMH was observed with the use of Er, Cr: YSGG laser in combination with Fluor Protector® varnish (Group 19) (478 ± 8.64), while the lowest value was seen with the use of Er, Cr: YSGG laser alone (Group 4) (375.95 ± 16.80). After the demineralization-remineralization cycle (C), the SMH of the enamel in groups (Group 3 to Group 19) decreased compared to post-enamel surface treatment (B); however, it remained higher than the baseline values (A). The highest SMH after the demineralization-remineralization cycle was recorded with the use of Er: YAG laser in combination with Fluor Protector® varnish (Group 11) (418.40 ± 4.17), while the lowest value was seen with the use of Er, Cr: YSGG laser alone (Group 4) (259 ± 15.53). The baseline SMH values for the positive (Group 1) and negative (Group 2) controls were 305.15 ± 33.61 and 305.80 ± 25.50, respectively. Following the demineralization-remineralization cycle, the SMH for the negative control (Group 2) was 199.05 ± 6.17. Figures 2 and 3 display the mean SMH of enamel among all groups after surface treatment and the demineralization-remineralization cycle, respectively, arranged in ascending order. Mean Difference in SMH (Δ1, Δ2, Δ3) (Table 2) Following enamel surface treatment, the highest mean difference in SMH (Δ1) was observed with the use of Er, Cr: YSGG laser in combination with Fluor Protector® varnish (Group-16) (166.65), while the lowest was seen in the Fluorovil® group (Group-5) (28.30). The highest mean difference following the demineralization-remineralization cycle (Δ2) was observed with the use of Er, Cr: YSGG laser alone (Group-4) (-116.95), and the lowest was seen with Fluor Protector® varnish (Group-6) (-33.75). The comparison of the mean difference between the baseline and post-demineralization-remineralization cycle (Δ3) showed the highest value with the Er: YAG laser in combination with Fluor Protector® varnish (Group-11) (105.30) and the lowest with the use of the Er: YAG laser alone (Group-3) (-16.5). Upon comparing the mean values of SMH among all groups in terms of Δ1, Δ2, and Δ3, there was a statistically significant difference between Δ1 (baseline) and Δ2 (following surface treatment of enamel), between Δ2 (following surface treatment of enamel) and Δ3 (after demineralization-remineralization cycle), as well as between Δ3 (after demineralization-remineralization cycle) and Δ1 (baseline). DISCUSSION Lasers have been shown to induce various surface alterations in enamel, such as crazing, cratering, and exfoliation. The study results indicate that both types of erbium lasers tested led to a significant increase in SMH compared to the positive control group. Although SMH decreased after exposure to an acidic challenge, the reduction was not substantial, and SMH remained higher than that of the negative control group. This alteration in SMH is attributed to the ability of erbium lasers to enhance enamel acid resistance by heating the surface during irradiation, which induces structural and chemical changes in dental hard tissue [ 20 ]. Various theories have been proposed to explain the increased SMH that resists demineralization following laser irradiation. One theory suggests that laser irradiation decreases enamel permeability due to the physical fusion of the enamel surface microstructure. Another theory posits a combination of reduced enamel permeability and solubility promoted by the melting, fusion, and recrystallization of enamel crystallites, which seal the enamel surface [ 21 ]. The reduction in enamel solubility may result from ultrastructural changes in enamel crystallography, such as decreased water and carbonate content, increased hydroxyl ion content, formation of pyrophosphates, and protein decomposition [ 22 ]. At temperatures ranging from 650°C to 1100°C, products formed in enamel decrease solubility, depending on the calcium-phosphate ratio. At 1100°C, new crystalline phases, including tetra-calcium diphosphate monoxide and alpha and beta phases of tricalcium phosphate form, which are less soluble, contain less carbonate, and are more resistant to demineralization [ 6 , 23 ]. Thus, the improved SMH results from the laser's efficiency in resisting demineralization rather than an actual increase in SMH [ 5 ]. The study's results indicate that laser treatment has a positive impact on the enamel surface, consistent with previous research reporting favorable outcomes from the use of erbium lasers [ 4 , 5 , 6 , 24 ]. However, some earlier studies did not observe such positive effects of erbium lasers on enamel [ 12 , 25 , 26 ]. Additionally, certain authors found no significant differences in enamel surface microhardness between the two types of erbium lasers [ 27 ]. Following the application of fluoridated and CPP-ACP-containing remineralizing agents, there was an observed increase in SMH of primary enamel. However, upon exposure to the demineralization-remineralization cycle, the SMH values decreased compared to the pre-treatment levels. Notwithstanding this reduction, the SMH remained higher than the baseline value. The observed increase in SMH was more pronounced with the application of remineralizing agents in varnish form, (MI Varnish® and Fluoro Protector®), when compared to paste or gel forms (Fluorovil®, MI Paste Plus® and MI Paste®). The increase in SMH with use of CPP-ACP containing (MI varnish, MI paste plus, and MI paste) remineralizing agents may be attributed to Protein nanotechnology. The Protein nanotechnology involving CPP-ACP combines specific phosphoproteins from bovine milk with ACP nanoparticles. The precise ratio consists of 144 calcium ions, 96 phosphate ions, and 6 peptides of CPP1. The mechanism of action CPP-ACP are: 1. Stabilization of calcium and phosphate ions : Under neutral and alkaline conditions, CPPs stabilize calcium and phosphate ions, creating metastable solutions that are supersaturated with respect to basic calcium phosphate phases. As the pH rises, CPPs bind more calcium and phosphate, reaching equilibrium where they have bound their equivalent weights of these ions1. 2. Formation of small ACP clusters : The phosphoserine present in CPP composition allows it to bind to calcium and phosphate ions, thus forming small clusters of ACP. These clusters are initially insoluble but become soluble in the presence of CPP1. 3. Enhancing remineralization : CPP also binds to the tooth surface, acting as a source of calcium and phosphate ions. These ions stabilize the calcium and phosphate phase and drive them into the porous structure of lesions. As a result, they deposit on relatively demineralized apatite crystals, reforming and enhancing remineralization1. 4. Maintaining the correct molar ratio : CPP helps to localize and stabilize these ions at the tooth surface in the correct molar ratio (Ca: PO4: F = 5:3:1) [ 5 – 7 , 18 , 28 ]. The higher SMH with MI varnish® may be attributed to the composition of the varnish, which, in addition to calcium and phosphate, contains 900 ppm of fluoride. The rapid penetration of this nano-complex into the enamel surface facilitates the precipitation of calcium, phosphate, and fluoride ions, leading to the formation of fluorapatite on the enamel surface, thereby enhancing SMH. Additionally, these agents likely deliver higher amounts of fluoride to demineralized enamel [ 30 ]. Further, the application of remineralizing agents in varnish form also likely increases enamel contact time, resulting in improved microhardness [ 7 , 8 ]. Furthermore, as the solvent in MI Varnish® evaporates, it leaves a significantly higher fluoride concentration (approximately ten times higher) on the tooth surface [ 7 ]. In contrast, MI Paste Plus® and MI Paste® are in a creamy form, which may not adequately wet the enamel surface [ 31 ]. These factors, combined with the presence of a nano-complex of calcium, phosphate, and fluoride ions, likely account for the highest SMH observed with MI Varnish®. These findings suggest that dental varnish is suitable for in-office use, while paste-form remineralizing agents (MI Paste Plus® and MI Paste®) are more appropriate for home use. The application of fluoridated varnish (Fluor Protector®) demonstrated a superior increase in SMH compared to other forms (Fluorovil®, MI Paste Plus® and MI Paste®) of remineralizing agents. Fluoride varnish increases fluoride concentration on the outer tooth surface, acting as a slow-releasing reservoir during the early stages of demineralization. The fluoride ions released from the varnish interact more effectively with enamel, resulting in reduced mineral loss, decreased enamel surface demineralization, and shallower carious lesions, along with increased enamel mineral content [ 7 ]. Fluoridated varnishes are also effective in reducing or arresting white spot lesions [ 4 ]. The inhibitory and remineralizing effect is primarily due to the formation of fluorhydroxyapatite or fluorapatite, which are harder and more resistant to acid dissolution than hydroxyapatite [ 32 ]. Furthermore, the Fluor Protector® contains 0.9% difluorsilane in a polyurethane varnish base, with ethyl acetate and isoamyl propionate as solvents. The fluoride content is equivalent to 0.1% or 1000 ppm in solution [ 7 ]. Upon solvent evaporation, the fluoride concentration on the tooth surface significantly increases, reaching levels nearly ten times higher. The irradiation of enamel with erbium lasers followed by the application of remineralizing agents resulted in significantly higher SMH compared to the use of lasers or remineralizing agents alone, as well as the baseline value. This increased SMH was maintained even after the acidic challenge, indicating a synergistic effect of laser treatment and remineralizing agents. Furthermore, this suggests that following laser irradiation, the uptake of fluoride, calcium, and phosphate ions into the tooth's crystalline structure is enhanced and firmly bound. These findings are consistent with previous studies [ 33 , 34 ]. The potential mechanisms for the increased SMH when treated with a combination of laser and remineralizing agents are as follows: 1. Reduction of Lattice Strain : Laser irradiation reduces the lattice strain of hydroxyapatite and decreases enamel solubility by altering the carbonate, water, and organic content of the tooth mineral phases. This process creates a morphologically hardened enamel surface that acts as a protective barrier against acid attack. Further, SEM analysis of erbium-treated enamel has revealed a smooth and glossy surface devoid of any cracks, making enamel impervious to acidic dissolution. 2. Microseive Creation : Laser treatment facilitates the creation of microseives, allowing the re-precipitation of mobilized calcium, phosphate, and fluoride ions during demineralization. 3. Reduction of Permeability : Laser irradiation reduces the permeability of the mineral structure due to protein denaturation and swelling. 4. Increased Uptake of Ions : The laser-altered enamel structure enhances the penetration of fluoride ions and the CCP-ACP nano-complex into the deep layers of the hydroxyapatite crystal. The increased fluoride, calcium, and phosphate mineral content in enamel enhance the laser's ability to inhibit demineralization and promote remineralization, thereby increasing SMH. 5. Formation of Surface Coating Reservoirs : Laser treatment creates surface coating reservoirs for calcium phosphate and fluoride. These numerous nanoclusters of fluoride, calcium, and phosphate deposits on the tooth surface can act as a reservoir to replenish the soluble calcium and phosphate ions that have diffused into the subsurface enamel. SEM studies have revealed increased deposition of spherical or globular deposits measuring 2–4 µm in size, resembling the morphology of calcium fluoride, which acts as a reservoir of mineral ions against acid attacks. Under high-risk clinical conditions, this has a bacteriostatic or bactericidal effect on plaque microorganisms [ 35 – 39 ]. Consistent with the findings of the present study, previous research has reported a significantly smaller reduction in SMH when lasers are used in conjunction with fluoride or CPP-ACP-containing remineralizing agents [ 4 – 6 , 8 , 15 ]. Therefore, in agreement with prior studies, the present study recommends the synergistic use of lasers and remineralizing agents to enhance SMH and serve as the most effective preventive measure for white spot lesions. However, contrasting findings have been reported in the literature, indicating no superiority in the SMH of primary enamel following the combined use of erbium or non-erbium lasers and remineralizing agents [ 12 , 25 , 26 , 30 ]. It is important to note that due to the high absorption of erbium laser by water, laser irradiation causes micro-explosions and subsequent ablation. This leads to the formation of an irregular enamel surface that enhances plaque accumulation. Therefore, these lasers should be used under sub-ablative conditions to improve chemical alterations, reduce unwanted morphological changes of the enamel surface, and preserve the pulp from potential thermal changes [ 40 ]. The highest synergistic effect was observed with the use of Er: YAG lasers in combination with varnishes, such as Fluor Protector® and MI Varnish®. This finding aligns with Babu et al., who reported a non-significant difference in SMH when treated with Fluor Protector® and MI Varnish® without laser irradiation of the enamel surface [ 7 ]. Consequently, varnishes containing CPP-ACP and fluoride can be effectively used as an alternative to fluoride varnish, especially since a high-fluoride strategy cannot be employed due to its adverse effects. There are inconsistencies in the literature regarding the optimal sequence for applying remineralizing agents and laser irradiation. Considering the laser's role in preserving remineralizing ions near the enamel, in the present study, laser irradiation was performed first, followed by the application of remineralizing agents, consistent with the methodology of some previous studies [ 5 , 6 , 18 ]. Furthermore, if remineralizing agents are applied before laser treatment, the laser may act as a barrier coat [ 39 ]. According to the results of this study, the two lasers used in this study had similar effects in increasing the SMH of primary tooth enamel. This finding aligns with Hawas et al., who reported no significant difference between the two types of erbium lasers and the combination of lasers with remineralizing agents in enhancing enamel SMH [ 27 ]. The findings of studies examining the effects of lasers on enamel microhardness are diverse and inconclusive. Some authors suggest that laser irradiation enhances SMH, while others have reported no enhancement, and some indicate no effect on enamel [ 4 – 6 , 8 – 12 , 40 ]. The discrepancies in these findings can be attributed to differences in laser types and parameters, the use of fluoride or non-fluoride remineralizing agents, demineralization methods, and SMH assessment techniques. Additional factors, such as the sequence of laser application, variations in tooth type, composition, patient age, storage medium, and study design further complicate the results [ 5 , 20 ]. These variations underscore the complexity of laser effects on enamel and highlight the need for standardized laser parameters for use in primary teeth. In the current study, we endeavored to minimize confounding factors. The teeth collected were from patients within the same age range, and a remineralizing solution with controlled pH was used to simulate the oral environment. All procedures were performed by a single operator. However, since this study was conducted in in-vitro conditions, caution should be exercised when extrapolating the findings to clinical settings. Although in-vitro research offers important insights, it cannot fully replicate the complexity of the oral environment. Clinical conditions like decayed tissue, tooth anatomy diversity, chemical composition, and the physical and chemical properties of saliva such as saliva flow rate, composition, and buffering capacity can significantly influence water content, ablation thresholds, and enamel structure removal, differing greatly from the controlled settings of in-vitro studies [ 6 , 7 ]. Additionally, factors such as aging, occlusal forces, acid erosion, and temperature fluctuations—absent in in-vitro studies—play an important role in the SMH of tooth structure and should be considered in future research. Future in-vivo studies with larger sample sizes are needed to determine the optimal parameters of erbium lasers for primary teeth under various assessment methods and to identify the sequence or method of applying remineralizing agents and lasers. Additionally, the effects of heat generation by lasers on the tooth surface and dental pulp should be studied to identify the safest and most effective laser wavelength and power for clinical use. CONCLUSION Laser irradiation alone increased the SMH compared to positive and negative groups of enamel surfaces. The application of remineralizing agents enhanced the SMH compared to baseline values, and positive and negative groups of enamel surfaces. The highest SMH was observed with the use of a laser in conjunction with varnish-form remineralizing agents. There was no significant difference in SMH between the use of Fluor Protector® and MI Varnish®. Erbium laser irradiation followed by the application of remineralizing agents demonstrated a synergistic effect in increasing enamel SMH, suggesting its potential use as a preventive measure for dental caries. Declarations Conflict of Interest /Competing Interests : The authors have no conflicts of interest to declare that are relevant to the content of this article. Human Ethics and Consent to Participate Informed written consent was secured from the parents or legal guardians, and assent was obtained from children aged 6 years and older, permitting the use of their teeth for research purposes. Ethics approval: Ethical clearance to conduct this study was obtained from the Institutional Ethics Committee (IEC/HIMS/RR235). The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Clinical trial number not applicable. Funding: No funds, grants, or other support was received in regard to the submitted work. Author Contribution GB: Conception of design, Acquisition of data, Interpretation of data, Drafting the article, Revision of article KG: Acquisition of data, Interpretation of data, Drafting the article, Revision of article GMD: Acquisition of data, Interpretation of data, Revision of articleAll authors approved the final version of the manuscript. Data Availability The data used to support the findings of this study can be made available upon request to the corresponding author. References Diaci J, Gaspirc B (2012) Review comparison of Er:YAG and Er,Cr:YSGG lasers used in dentistry. J Laser Health Acad 1(1):1–13 Perhavec T, Gorkič A, Bračun D, Diaci J (2009) A method for rapid measure ment of laser ablation rate of hard dental tissue. Opt Laser Technol 41(4):397–402 Diaci J (2008) Laser profilometry for the characterization of craters produced in hard dental issues by Er:YAG and Er,Cr:YSGG lasers. 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Photomed Laser Surg 22(4):312–317 Esteves-Oliveira M, Pasaporti C, Heussen N, Eduardo CP, Lampert F, Apel C (2011) Rehardening of acid-softened enamel and prevention of enamel softening through CO2 laser irradiation. J Dent 39(6):414–421 Faggion CM Jr (2012) Guidelines for reporting pre-clinical in vitro studies on dental materials. J Evid Based Dent Pract 12(4):182–189 Molla Asadollah F, Mojahedi SM, Nojedehian H, Asnaashari M, Asnaashari N (2019) The Effect of Er:YAG Laser Irradiation Combined With Fluoride Application on the Resistance of Primary and Permanent Dental Enamel to Erosion. J Lasers Med Sci 10(4):290–296 International Organization for Standardization ISO/TS 11405 (2003) Technical Specifications Dental materials-testing of adhesion to tooth structure, 2nd edition. Switzerland Torabinejad M, Bahjri K (2005) Essential elements of evidenced-based endodontics: steps involved in conducting clinical research. J Endod. 2005;31(8):563-9 Ghelejkhani A, Nadalizadeh S, Rajabi M (2021) Effect of casein-phosphopeptide amorphous calcium phosphate and fluoride with/without erbium, chromium-doped yttrium, scandium, gallium, and garnet laser irradiation on enamel microhardness of permanent teeth. Dent Res J (Isfahan). 17; 18:20 ten Cate JM, Duijsters PP (1982) Alternating demineralization and remineralization of artificial enamel lesions. Caries Res 16(3):201–210 de Freitas PM, Rapozo-Hilo M, Eduardo Cde P, Featherstone JD (2010) In vitro evaluation of erbium, chromium: yttrium-scandium-gallium-garnet laser-treated enamel demineralization. Lasers Med Sci 25(2):165–170 Ana P, Bachmann L, Zezell MD (2006) Lasers effects on enamel for caries prevention. Laser Phys 16:865–875 Featherstone JD, Nelson DG (1987) Laser effects on dental hard tissues. Adv Dent Res 1(1):21–26 Bachmann L, Craievich AF, Zezell DM (2004) Crystalline structure of dental enamel after Ho:YLF laser irradiation. 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J Conserv Dent 13(1):42–46 Delbem AC, Cury JA, Nakassima CK, Gouveia VG, Theodoro LH (2003) Effect of Er:YAG laser on CaF2 formation and its anti-cariogenic action on human enamel: an in vitro study. J Clin Laser Med Surg 21(4):197–201 Mathew A, Reddy NV, Sugumaran DK, Peter J, Shameer M, Dauravu LM (2013) Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co2 laser) and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis. Contemp Clin Dent 4(2):170–175 Anaraki SN, Serajzadeh M, Fekrazad R (2012) Effects of laser-assisted fluoride therapy with a CO2 laser and Er, Cr:YSGG laser on enamel demineralization. Pediatr Dent 34(4):e92–96 Kaur T, Tripathi T, Rai P, Kanase A (2017) SEM Evaluation of Enamel Surface Changes and Enamel Microhardness around Orthodontic Brackets after Application of CO 2 Laser, Er,Cr:YSGG Laser and Fluoride Varnish: An In vivo Study. 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Lasers Med Sci 23(2):141–147 Tables Table-1: Materials used, and the procedure protocol followed for surface treatment of enamel Groups Details of the remineralizing agents Enamel surface treatment Group-1 Positive control The enamel samples were left untreated and did not undergo any surface modifications [5]. Group-2 Negative control The enamel samples underwent only the demineralization-remineralization cycle [5]. Group-3 Er: YAG laser (Fidelis; Fotona, Medical Laser, Ljubljana, Slovenia)/(Smart 2940D plus, Deka, Calenzana, Italy) The enamel samples were irradiated with an Er:YAG laser (wavelength 2.940 nm, 100 mJ pulsed energy, 1.59 J/cm² energy density, 1 W power, 10 Hz frequency, 250 µs pulse width, 10-second duration, 1 mm spot diameter, and 50% water) using a swiping motion over the entire enamel surface in a non-contact mode. This was achieved by attaching an endodontic file to the handpiece, maintaining a 1 mm distance from the enamel surface [15]. Group-4 Er,Cr:YSGG laser (Water Lase MD System, BioLase Technology Inc., San Clemente, CA, USA) The enamel samples were irradiated with an Er,Cr:YSGG laser (wavelength 2.780 nm, 1.5 W, 35 mJ energy per pulse, and 17.8 J/cm² energy density). The laser was directed over the entire enamel surface in a non-contact mode using a turbo handpiece with an MX5 short insert (0.5 mm diameter) at 20 Hz frequency under an air/water spray (40% air, 60% water). The non-contact mode was ensured by attaching an endodontic file to the handpiece, maintaining a 1 mm distance from the enamel surface [5,6]. Group-5 Fluorovil® (Vishal Dentocare Pvt.Ltd., India) (Acidulated phosphate fluoride gel) Fluorovil® gel was applied to the enamel samples for 4 minutes using a cotton swab, then removed with gauze. The specimens were washed with deionized water for 1 minute. Following this, the enamel specimens were stored in deionized water for 24 hours and subsequently subjected to a 7-day demineralization-remineralization cycle [5,15]. Group-6 Fluor Protector® varnish (Ivoclar Vivadent, Amherst, N. J, USA) (Fluoride in varnish form) A thin layer of Fluor Protector® varnish was applied to the enamel surface according to the manufacturer's instructions, using the provided soft-bristled applicator tip. After 24 hours, the varnish was carefully removed from the enamel samples using cotton swabs soaked in acetone, and the specimens were then washed with deionized water for 1 minute. Subsequently, the specimens were stored in deionized water for 24 hours and then subjected to a 7-day demineralization-remineralization cycle [5,7]. Group-7 MI Paste® (GC India Dental Pvt Ltd., India (Casein phosphopeptide-amorphous calcium phosphate paste) The enamel samples were treated with MI Paste® using an applicator tip and left for 3 minutes. They were then cleaned with cotton rolls and washed with deionized water for 1 minute. After this, the specimens were stored in deionized water for 24 hours and subsequently subjected to a 7-day demineralization-remineralization cycle. The application of MI Paste® was repeated daily at the same time throughout the 7-day cycle [4,5]. Group-8 MI Paste Plus ® (GC India Dental Pvt Ltd., India (Casein phosphopeptide-amorphous calcium phosphate paste+ fluoride) The enamel samples were treated with MI Paste Plus® using an applicator tip and left for 3 minutes. They were then cleaned with cotton rolls and washed with deionized water for 1 minute. Following this, the specimens were stored in deionized water for 24 hours and subsequently subjected to a 7-day demineralization-remineralization cycle. The application procedure of MI Paste Plus® was repeated daily at the same time throughout the 7-day cycle [18]. Group-9 MI varnish ® (GC India Dental Pvt Ltd., India) (Casein phosphopeptide-amorphous calcium phosphate paste+ fluoride) The enamel samples were treated with MI Varnish® using the manufacturer's provided applicator tip. After 24 hours, the varnish was carefully removed from the enamel samples using cotton swabs soaked in acetone, and then the specimens were washed with deionized water for 1 minute. Following this, the specimens were stored in deionized water for 24 hours and subsequently subjected to a 7-day demineralization-remineralization cycle [7]. Group-10 Er: YAG + Fluorovil® The enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of Fluorovil® gel as described above [5,15]. Group-11 Er: YAG + Fluor Protector® varnish The enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of Fluor Protector® varnish as previously described [7,15]. Group-12 Er: YAG + MI Paste® The enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of MI Paste® as described earlier[5,15]. Group-13 Er: YAG + MI Paste Plus® The enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of MI Paste Plus® as described earlier[15,18]. Group-14 Er: YAG + MI Varnish® The enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of MI Varnish® as described earlier [7,15]. Group-15 Er,Cr:YSGG + Fluorovil® The enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of Fluorovil® gel as described earlier [5,6]. Group-16 Er,Cr:YSGG + Fluor Protector® varnish The enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of Fluor Protector® varnish as described earlier [5,7]. Group-17 Er,Cr:YSGG + MI Paste® The enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of MI Paste® as described earlier [5]. Group-18 Er,Cr:YSGG + MI Paste Plus® The enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of MI Paste Plus® as described earlier [5,18]. Group-19 Er,Cr:YSGG+ MI Varnish® The enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of MI Varnish® as described earlier [5,7]. TABLE -2: Comparison of mean surface microhardness of enamel between different groups at baseline, after treatment and after pH cycle using One-way ANOVA Test Groups Baseline-A After treatment-B After Demineralization-Remineralization cycle-C B-A (Δ1) P value C-B (Δ2) P value C-A (Δ3) P value G-1 Positive control 305.15±33.61 - - - - - - - - G-2 Negative control 305.80±25.50 - 199.05±6.17 - - - -106.75 <0.001* G-3 Only Er:YAG laser 298.45±29.83 386.90±16.75 281.95±14.57 88.45 0.10 -104.95 0.10 -16.5 <0.001* G-4 Only Er,Cr:YSGG 306.60±21.17 375.95±16.80 259.00±15.53 69.35 <0.001* -116.95 <0.001* -47.6 <0.001* G-5 Fluorovil® 353.45±18.27 381.75±7.65 269.60±7.56 28.30 <0.001* -112.15 <0.001* -83.85 <0.001* G-6 Fluor Protector® Varnish 315.50±31.47 417.60±13.77 383.85±5.98 102.10 <0.001* -33.75 <0.001* 68.35 <0.001* G-7 MI Paste® 310.35±28.40 395.65±11.32 332.20±11.50 85.30 <0.001* -63.45 0.01* 21.85 <0.001* G-8 MI Paste Plus® 337.60±30.89 404.25±12.17 366.35±23.08 66.65 <0.001* -37.90 <0.001* 28.75 0.01* G-9 MI Varnish® 335.60±15.93 444.45±10.32 393.15±10.63 108.85 <0.001* -51.30 <0.001* 57.55 <0.001* G-10 Er:YAG+ Fluorovil® 321.35±26.32 409.95±10.81 303.00±11.87 88.60 <0.001* -106.95 0.02* 18.35 <0.001* G-11 Er:YAG+ Fluor Protector® Varnish 313.10±35.21 462.10±86.72 418.40±4.17 149.00 <0.001* -43.7 <0.001* 105.30 0.11 G-12 Er:YAG+MI Paste® 328.95±32.52 435.30±18.86 390.45±15.11 106.35 <0.001* -44.85 <0.001* 61.5 <0.001* G-13 Er:YAG+MI Paste Plus® 334.95±21.65 476.65±13.05 397.50±18.27 141.70 <0.001* -79.15 <0.001* 62.55 <0.001* G-14 Er:YAG+MI Varnish® 338.60±34.51 476.45±15.05 404.90±19.47 137.85 <0.001* -71.55 <0.001* 66.3 <0.001* G-15 Er,Cr:YSGG+ Fluorovil® 308.75±42.97 391.90±11.53 293.15±10.59 83.15 <0.001* -98.75 0.43 -15.6 <0.001* G-16 Er,Cr:YSGG+ Fluor Protector® Varnish 311.35±19.50 478.00±8.64 386.85±8.36 166.65 <0.001* -91.15 <0.001* 75.5 <0.001* G-17 Er,Cr:YSGG+MI Paste® 317.15±27.39 418.85±8.50 355.80±5.44 101.70 <0.001* -63.05 <0.001* 38.65 <0.001* G-18 Er,Cr:YSGG+MI Paste Plus® 314.45±18.60 448.35±12.42 383.95±8.02 133.90 <0.001* -64.4 <0.001* 69.5 <0.001* G-19 Er,Cr:YSGG+MI Varnish® 333.95±31.64 473.05±8.41 399.45±12.54 139.10 <0.001* -73.6 <0.001* 65.5 <0.001* *Stastically significant using One-way ANOVA Test Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 15 Apr, 2025 Read the published version in Lasers in Medical Science → Version 1 posted Editorial decision: Revision requested 05 Mar, 2025 Reviews received at journal 03 Mar, 2025 Reviews received at journal 11 Feb, 2025 Reviewers agreed at journal 11 Feb, 2025 Reviewers agreed at journal 10 Feb, 2025 Reviewers invited by journal 17 Jan, 2025 Editor assigned by journal 14 Jan, 2025 Submission checks completed at journal 06 Jan, 2025 First submitted to journal 28 Dec, 2024 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. We do this by developing innovative software and high quality services for the global research community. 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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-5727275","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":398343516,"identity":"f8bec3da-8747-43b6-8929-a402ad5085c3","order_by":0,"name":"Girish Babu KL","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA50lEQVRIie3QPQrCMBTA8YTAcwm6pqh4hUChdrJXSRGcujmJ4AeC5+kUEBwKhXbxAAWXVkHctIOgm4ng2nYUzB8a3vB+kBQhk+kXi9QnEEN8cCtzNdN2c4KEzTWBRkSniMP0UEva6eZ8LfauN0TRZPYIRj1ApDhlFcQ6JI4rLszfrVfJsS/H6mJg20EF4VkAXERM8Bhvj5YkilDoNiEeTwhMLblsREiuCA4PALiUcT3Rb0GK+GFGSRfLlAKpeYv+Y+UzWng8o7h8ybnXaW2KcxVRAftOhH7O6vXPyv074Wf9tslkMv1hbxseSVx/zhGaAAAAAElFTkSuQmCC","orcid":"","institution":"Hassan Institute of Medical Sciences","correspondingAuthor":true,"prefix":"","firstName":"Girish","middleName":"Babu","lastName":"KL","suffix":""},{"id":398343518,"identity":"ea08c5e6-14b7-4b9e-b82d-891d5af4ae90","order_by":1,"name":"Kavyashree Gururaj Hebbar","email":"","orcid":"","institution":"Hassan Institute of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Kavyashree","middleName":"Gururaj","lastName":"Hebbar","suffix":""},{"id":398343524,"identity":"c9078f23-5ee3-44d6-9271-00f920c09d70","order_by":2,"name":"Geeta Maruti Doddamani","email":"","orcid":"","institution":"Dr Symala Reddy Dental College, Hospital and Research Center","correspondingAuthor":false,"prefix":"","firstName":"Geeta","middleName":"Maruti","lastName":"Doddamani","suffix":""}],"badges":[],"createdAt":"2024-12-28 17:38:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5727275/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5727275/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10103-025-04451-6","type":"published","date":"2025-04-15T15:57:01+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":73311240,"identity":"1f9ce681-e2e9-4efb-9e24-5c94cf77175d","added_by":"auto","created_at":"2025-01-08 18:16:59","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":49441,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFlowchart followed during the study\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5727275/v1/248f837df6e7ce5a8fc60244.png"},{"id":73311242,"identity":"20b4c0c8-177d-4ea2-84fa-4c69c4045812","added_by":"auto","created_at":"2025-01-08 18:16:59","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":246487,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMean surface microhardness of enamel among the groups following planned surface treatment arranged in ascending order\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5727275/v1/ea0d41527c73b22302fe09bc.jpg"},{"id":73311243,"identity":"469c0dd2-7991-4c51-8ff8-471d2f8db86b","added_by":"auto","created_at":"2025-01-08 18:16:59","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":240158,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMean surface microhardness of enamel among the groups following demineralization- remineralization cycle arranged in ascending order\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Picture3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5727275/v1/cdc18b9fe81b586509ee1029.jpg"},{"id":81050746,"identity":"b7dedb6c-3147-4991-915a-174ba159152b","added_by":"auto","created_at":"2025-04-21 16:03:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1744547,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5727275/v1/d9444761-8a3c-4bd4-a4fd-936da44141cd.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Synergistic effect of laser irradiation and remineralizing agents on surface microhardness of primary tooth enamel -An in-vitro study","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eLasers have revolutionized pediatric dentistry by providing a range of treatments for children, including caries prevention, detection, removal, cavity preparation, and the sealing of pits and fissures. Among these, erbium lasers, namely Er: YAG (wavelength of 2940 nm) and Er, Cr: YSGG (wavelength of 2780 nm), are particularly promising for use on mineralized dental tissues. While both lasers are effective and safe, they differ in wavelength, absorption, and ablation efficiency. The Er: YAG laser exhibits a threefold higher absorption coefficient compared to the Er, Cr: YSGG laser, resulting in deeper heat penetration into irradiated tissue or material for the latter, which produces a thicker indirectly heated zone. This excess heating can reduce ablation efficiency and increase charring compared to the Er: YAG laser [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Consequently, the Er: YAG laser is more efficient for enamel and dentin treatment due to its superior absorption characteristics [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. However, some studies have found that both types of erbium lasers comparably enhance enamel microhardness [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEarly enamel lesions have the potential for remineralization, increasing their enamel surface resistance to further acid challenges, especially with enhanced remineralization treatments. The application of remineralizing agents, such as fluoride gels, varnishes, dentifrices, and casein phosphopeptide amorphous calcium phosphate (CPP-ACP) agents, increases the availability of calcium, phosphate, and fluoride ions in the oral environment. This enhances the remineralization process, reduces demineralization, and increases the surface microhardness (SMH) of enamel [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eContradictory reports exist regarding the cumulative effects of lasers and remineralizing agents on enamel. Some studies have shown positive results, while others have reported negative outcomes or no effect [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan additionalcitationids=\"CR9 CR10 CR11\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Additionally, most studies have focused on permanent teeth and primarily assessed mineral loss, fluoride content, and enamel surface topography following laser irradiation [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Furthermore, the impact of laser treatment on primary tooth enamel differs from that on permanent tooth enamel. There is also a lack of research evaluating the effects of erbium lasers in conjunction with remineralizing agents on primary tooth enamel. Therefore, the purpose of this study is to evaluate the synergistic effect of erbium laser irradiation and remineralizing agents on the surface microhardness of primary tooth enamel.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eEthical Considerations\u003c/h2\u003e \u003cp\u003e The study followed a randomized, controlled, parallel in-vitro design and obtained approval from the Institutional Ethics Committee (IEC/HIMS/RR235). Throughout the research, adherence to established guidelines for reporting pre-clinical in-vitro studies on dental materials was maintained [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The study also aligned with the ethical principles outlined in the World Medical Association's Declaration of Helsinki and followed the CONSORT guidelines for study design (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSample size calculation\u003c/h3\u003e\n\u003cp\u003eBased on the previous studies [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] the sample size estimation was performed at 5% alpha error (α\u0026thinsp;=\u0026thinsp;0.05), with an effect size of 0.36 and the power of the study at 80% using G Power software (latest ver. 3.1.9.7; Heinrich-Heine- Universi-ta ̈t Du ̈sseldorf, Du ̈sseldorf, Germany). The estimation demonstrated that a minimum of 20 samples were in each group, thus the total samples consisted of 380.\u003c/p\u003e\n\u003ch3\u003eTeeth Sample Collection\u003c/h3\u003e\n\u003cp\u003eThe sound human primary molars extracted from normal and healthy children 6 to 9 years visiting the department were collected. Parents or legal guardians received detailed information about the study's objectives, procedures, outcomes, and associated risks and benefits. After addressing their questions, written consent was obtained, and the children provided their assent. A total of 427 teeth were collected, and extracted for reasons such as orthodontic needs, over-retention, or pre-shedding mobility causing discomfort [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\n\u003ch3\u003eSelection Criteria for Teeth\u003c/h3\u003e\n\u003cp\u003eOnly teeth without cracks, restorations, caries, fluorosis, abrasion, or other anomalies/imperfections were selected. Any teeth with caries, developmental defects, a history of pulpectomy, or damage during extraction were excluded, resulting in a final sample of 380 teeth [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\n\u003ch3\u003ePreparation of Teeth Samples\u003c/h3\u003e\n\u003cp\u003eFollowing extraction, the teeth were immediately placed in a 0.9% saline solution. Within 24 hours, they underwent cleaning to remove soft debris, calculus, and stains using scrapers and ultrasonic scalers. Subsequently, pumice was applied with a rubber cup under water cooling for polishing. The prepared teeth were then stored in dark glass containers containing a 1% thymol solution for disinfection over a week at room temperature and to keep the samples moist to avoid dehydration which leads to enamel brittleness. Afterward, thorough rinsing with tap water for 2 hours eliminated any remaining thymol residues. The roots of the teeth were separated from the crowns using a water-cooled high-speed diamond bur. Finally, all teeth were examined under 40X magnification to detect any surface defects or cracks [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePolyvinyl plastic cylinder tubes (Zhejiang Liutongplas tics Co., Ltd., China) were cut into equal rings with a 20 mm diameter and 8 mm depth with parallel and flat top and bottom sides to make samples suitable for the microhardness test. After that, each ring was filled with autopolymerizing acrylic resin (Acropars, Tehran, Iran), and the teeth were embedded in the center of the ring so that the buccal surface remained exposed and facing upward. To prepare the enamel surfaces, they were ground flat and polished under continuous water cooling. This polishing process involved using silicon carbide abrasive papers with varying grit sizes: 800, 1200, and 2000-grit. The goal was to achieve a flat and smooth enamel surface. Following, each specimen was rechecked to confirm the absence of any cracks or fractures under the digital microscope at 50x magnification [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eNext, adhesive tapes measuring 3 \u0026times; 3 mm\u0026sup2; were placed on the enamel samples. The remaining surface was coated with two layers of nail varnish. After the nail varnish dried, the tapes were removed, and the samples were rinsed with deionized water. This standardized the enamel window surface to 3 \u0026times; 3 mm\u0026sup2; for all teeth. Each tooth sample was then coded with a marker, and a bur was placed in a high-speed handpiece. The samples were stored in deionized water until the planned procedure was carried out, which was carried out within one month [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eMeasurement of Baseline Surface Micro-hardness (First SMH)\u003c/h2\u003e \u003cp\u003eThe baseline SMH of the primary enamel was measured using a calibrated Vickers micro-hardness tester (Shimadzu HMV-2000/Shimadzu Corporation, Kyoto, Japan). SMH of each sample was assessed by making five indentations on enamel by applying 200g of load for 10 s. The indentations were strategically placed on the left upper, left lower, central, right upper, and right lower parts of the enamel samples. The value displayed on the machine was noted. The mean of the five values was calculated and recorded as the SMH of the respective sample [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The values were expressed in VHN. The baseline SMH of all the samples was measured to rule out any variations of enamel samples. SMH in all three groups was measured and found to have no statistically significant difference. Hence, changes in microhardness values after intervention would be attributed to the laser/ laser\u0026thinsp;+\u0026thinsp;remineralizing agent therapy.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eRandomization\u003c/h3\u003e\n\u003cp\u003eThe 380 selected teeth were randomly assigned into 19 groups, with each group containing 20 teeth. The allocation was based on the type of enamel surface treatment. To ensure randomization, a block randomization technique was employed, using varying block sizes. An assistant, not directly involved in the study, provided a computer-generated sequence for this purpose. The allocation process was carried out using sealed envelopes, each with a unique serial number, which was opened just before applying the enamel surface treatment [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\n\u003ch3\u003eIntervention\u003c/h3\u003e\n\u003cp\u003eThe selected teeth samples in the groups were subjected to enamel surface treatment as shown in table-1.\u003c/p\u003e \u003cp\u003eAfter the enamel surface treatment, the SMH of enamel (second SMH) was measured using the Vickers micro-hardness tester as described earlier [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eDemineralization-remineralization cycle [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/h2\u003e \u003cp\u003e Following, all the teeth samples, except samples of group 1, were subjected to a demineralization-remineralization cycle simulating a high caries challenge.14 Each enamel sample was placed in a separate container and immersed in demineralizing solution (2 mM CaCl2, 2.2 mM NaH2PO4,0.05 M CH3COOH, 1 M KOH pH:4.5) for 6 h once a day, followed by rinsing with distilled and deionized water for 10 second and gentle drying with absorbent paper. Then the specimens were individually immersed in the remineralization solution (1.5 mM CaCl2, 0.9 mM NaH2PO4, and 0.15M KCL, pH:7.0) for the remaining 18 h of the day. All procedures were carried out at 370C. After, 5 days of the cycle, the samples were left in remineralization solution for 2 days, and the cycle was completed. The solutions were renewed every 3 days and changed daily. On the 8th day, all the samples were taken out of the solution and dried using blotting paper. Following, the samples were rinsed with saline for 10 seconds, and their SMH of enamel (Third SMH) was measured using a Vickers micro-hardness tester as described earlier. The demineralization and remineralization cycle model allowed the evaluation of changes on the outermost enamel layer during caries development.\u003c/p\u003e \u003cp\u003eAll treatments were performed by a single skillful and trained operator. The single-calibrated examiner assessed the SMH.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eBlinding\u003c/h2\u003e \u003cp\u003eThe assessor of SMH and data analyzing statistician were blinded to the type of enamel surface treatments to prevent bias, while the operator performing the treatments could not be blinded due to the nature of the procedures.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eThe data obtained was tabulated and subjected to statistical analysis. Statistical Package for Social Sciences [SPSS] for Windows Version 22.0 Released 2013. Armonk, NY: IBM Corp., was used to perform statistical analyses. Descriptive Statistics: Descriptive analysis includes expression of SMH in terms of Mean \u0026amp; SD for each group. Inferential Statistics: One-way ANOVA Test followed by Tukey's post hoc Test and Independent Student t-test was used to compare the mean SMH between groups. The level of significance was set at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eMean Surface Microhardness (SMH) Values\u003c/h2\u003e \u003cp\u003eThe mean SMH values for each group are presented in Table\u0026nbsp;2. Following the planned enamel surface treatment (B), an increase in SMH was observed across all groups (Group 3 to Group 19) compared to baseline values (A). The greatest increase in SMH was observed with the use of Er, Cr: YSGG laser in combination with Fluor Protector\u0026reg; varnish (Group 19) (478\u0026thinsp;\u0026plusmn;\u0026thinsp;8.64), while the lowest value was seen with the use of Er, Cr: YSGG laser alone (Group 4) (375.95\u0026thinsp;\u0026plusmn;\u0026thinsp;16.80).\u003c/p\u003e \u003cp\u003eAfter the demineralization-remineralization cycle (C), the SMH of the enamel in groups (Group 3 to Group 19) decreased compared to post-enamel surface treatment (B); however, it remained higher than the baseline values (A). The highest SMH after the demineralization-remineralization cycle was recorded with the use of Er: YAG laser in combination with Fluor Protector\u0026reg; varnish (Group 11) (418.40\u0026thinsp;\u0026plusmn;\u0026thinsp;4.17), while the lowest value was seen with the use of Er, Cr: YSGG laser alone (Group 4) (259\u0026thinsp;\u0026plusmn;\u0026thinsp;15.53). The baseline SMH values for the positive (Group 1) and negative (Group 2) controls were 305.15\u0026thinsp;\u0026plusmn;\u0026thinsp;33.61 and 305.80\u0026thinsp;\u0026plusmn;\u0026thinsp;25.50, respectively. Following the demineralization-remineralization cycle, the SMH for the negative control (Group 2) was 199.05\u0026thinsp;\u0026plusmn;\u0026thinsp;6.17. Figures\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e display the mean SMH of enamel among all groups after surface treatment and the demineralization-remineralization cycle, respectively, arranged in ascending order.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eMean Difference in SMH (Δ1, Δ2, Δ3) (Table\u0026nbsp;2)\u003c/h2\u003e \u003cp\u003eFollowing enamel surface treatment, the highest mean difference in SMH (Δ1) was observed with the use of Er, Cr: YSGG laser in combination with Fluor Protector\u0026reg; varnish (Group-16) (166.65), while the lowest was seen in the Fluorovil\u0026reg; group (Group-5) (28.30). The highest mean difference following the demineralization-remineralization cycle (Δ2) was observed with the use of Er, Cr: YSGG laser alone (Group-4) (-116.95), and the lowest was seen with Fluor Protector\u0026reg; varnish (Group-6) (-33.75). The comparison of the mean difference between the baseline and post-demineralization-remineralization cycle (Δ3) showed the highest value with the Er: YAG laser in combination with Fluor Protector\u0026reg; varnish (Group-11) (105.30) and the lowest with the use of the Er: YAG laser alone (Group-3) (-16.5).\u003c/p\u003e \u003cp\u003eUpon comparing the mean values of SMH among all groups in terms of Δ1, Δ2, and Δ3, there was a statistically significant difference between Δ1 (baseline) and Δ2 (following surface treatment of enamel), between Δ2 (following surface treatment of enamel) and Δ3 (after demineralization-remineralization cycle), as well as between Δ3 (after demineralization-remineralization cycle) and Δ1 (baseline).\u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eLasers have been shown to induce various surface alterations in enamel, such as crazing, cratering, and exfoliation. The study results indicate that both types of erbium lasers tested led to a significant increase in SMH compared to the positive control group. Although SMH decreased after exposure to an acidic challenge, the reduction was not substantial, and SMH remained higher than that of the negative control group. This alteration in SMH is attributed to the ability of erbium lasers to enhance enamel acid resistance by heating the surface during irradiation, which induces structural and chemical changes in dental hard tissue [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eVarious theories have been proposed to explain the increased SMH that resists demineralization following laser irradiation. One theory suggests that laser irradiation decreases enamel permeability due to the physical fusion of the enamel surface microstructure. Another theory posits a combination of reduced enamel permeability and solubility promoted by the melting, fusion, and recrystallization of enamel crystallites, which seal the enamel surface [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. The reduction in enamel solubility may result from ultrastructural changes in enamel crystallography, such as decreased water and carbonate content, increased hydroxyl ion content, formation of pyrophosphates, and protein decomposition [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. At temperatures ranging from 650\u0026deg;C to 1100\u0026deg;C, products formed in enamel decrease solubility, depending on the calcium-phosphate ratio. At 1100\u0026deg;C, new crystalline phases, including tetra-calcium diphosphate monoxide and alpha and beta phases of tricalcium phosphate form, which are less soluble, contain less carbonate, and are more resistant to demineralization [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Thus, the improved SMH results from the laser's efficiency in resisting demineralization rather than an actual increase in SMH [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe study's results indicate that laser treatment has a positive impact on the enamel surface, consistent with previous research reporting favorable outcomes from the use of erbium lasers [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. However, some earlier studies did not observe such positive effects of erbium lasers on enamel [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Additionally, certain authors found no significant differences in enamel surface microhardness between the two types of erbium lasers [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFollowing the application of fluoridated and CPP-ACP-containing remineralizing agents, there was an observed increase in SMH of primary enamel. However, upon exposure to the demineralization-remineralization cycle, the SMH values decreased compared to the pre-treatment levels. Notwithstanding this reduction, the SMH remained higher than the baseline value. The observed increase in SMH was more pronounced with the application of remineralizing agents in varnish form, (MI Varnish\u0026reg; and Fluoro Protector\u0026reg;), when compared to paste or gel forms (Fluorovil\u0026reg;, MI Paste Plus\u0026reg; and MI Paste\u0026reg;).\u003c/p\u003e \u003cp\u003eThe increase in SMH with use of CPP-ACP containing (MI varnish, MI paste plus, and MI paste) remineralizing agents may be attributed to Protein nanotechnology. The Protein nanotechnology involving CPP-ACP combines specific phosphoproteins from bovine milk with ACP nanoparticles. The precise ratio consists of 144 calcium ions, 96 phosphate ions, and 6 peptides of CPP1. The mechanism of action CPP-ACP are: \u003cb\u003e1. Stabilization of calcium and phosphate ions\u003c/b\u003e: Under neutral and alkaline conditions, CPPs stabilize calcium and phosphate ions, creating metastable solutions that are supersaturated with respect to basic calcium phosphate phases. As the pH rises, CPPs bind more calcium and phosphate, reaching equilibrium where they have bound their equivalent weights of these ions1. \u003cb\u003e2. Formation of small ACP clusters\u003c/b\u003e: The phosphoserine present in CPP composition allows it to bind to calcium and phosphate ions, thus forming small clusters of ACP. These clusters are initially insoluble but become soluble in the presence of CPP1. \u003cb\u003e3. Enhancing remineralization\u003c/b\u003e: CPP also binds to the tooth surface, acting as a source of calcium and phosphate ions. These ions stabilize the calcium and phosphate phase and drive them into the porous structure of lesions. As a result, they deposit on relatively demineralized apatite crystals, reforming and enhancing remineralization1. \u003cb\u003e4. Maintaining the correct molar ratio\u003c/b\u003e: CPP helps to localize and stabilize these ions at the tooth surface in the correct molar ratio (Ca: PO4: F\u0026thinsp;=\u0026thinsp;5:3:1) [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe higher SMH with MI varnish\u0026reg; may be attributed to the composition of the varnish, which, in addition to calcium and phosphate, contains 900 ppm of fluoride. The rapid penetration of this nano-complex into the enamel surface facilitates the precipitation of calcium, phosphate, and fluoride ions, leading to the formation of fluorapatite on the enamel surface, thereby enhancing SMH. Additionally, these agents likely deliver higher amounts of fluoride to demineralized enamel [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Further, the application of remineralizing agents in varnish form also likely increases enamel contact time, resulting in improved microhardness [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Furthermore, as the solvent in MI Varnish\u0026reg; evaporates, it leaves a significantly higher fluoride concentration (approximately ten times higher) on the tooth surface [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In contrast, MI Paste Plus\u0026reg; and MI Paste\u0026reg; are in a creamy form, which may not adequately wet the enamel surface [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. These factors, combined with the presence of a nano-complex of calcium, phosphate, and fluoride ions, likely account for the highest SMH observed with MI Varnish\u0026reg;. These findings suggest that dental varnish is suitable for in-office use, while paste-form remineralizing agents (MI Paste Plus\u0026reg; and MI Paste\u0026reg;) are more appropriate for home use.\u003c/p\u003e \u003cp\u003eThe application of fluoridated varnish (Fluor Protector\u0026reg;) demonstrated a superior increase in SMH compared to other forms (Fluorovil\u0026reg;, MI Paste Plus\u0026reg; and MI Paste\u0026reg;) of remineralizing agents. Fluoride varnish increases fluoride concentration on the outer tooth surface, acting as a slow-releasing reservoir during the early stages of demineralization. The fluoride ions released from the varnish interact more effectively with enamel, resulting in reduced mineral loss, decreased enamel surface demineralization, and shallower carious lesions, along with increased enamel mineral content [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Fluoridated varnishes are also effective in reducing or arresting white spot lesions [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The inhibitory and remineralizing effect is primarily due to the formation of fluorhydroxyapatite or fluorapatite, which are harder and more resistant to acid dissolution than hydroxyapatite [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Furthermore, the Fluor Protector\u0026reg; contains 0.9% difluorsilane in a polyurethane varnish base, with ethyl acetate and isoamyl propionate as solvents. The fluoride content is equivalent to 0.1% or 1000 ppm in solution [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Upon solvent evaporation, the fluoride concentration on the tooth surface significantly increases, reaching levels nearly ten times higher.\u003c/p\u003e \u003cp\u003eThe irradiation of enamel with erbium lasers followed by the application of remineralizing agents resulted in significantly higher SMH compared to the use of lasers or remineralizing agents alone, as well as the baseline value. This increased SMH was maintained even after the acidic challenge, indicating a synergistic effect of laser treatment and remineralizing agents. Furthermore, this suggests that following laser irradiation, the uptake of fluoride, calcium, and phosphate ions into the tooth's crystalline structure is enhanced and firmly bound. These findings are consistent with previous studies [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe potential mechanisms for the increased SMH when treated with a combination of laser and remineralizing agents are as follows: \u003cb\u003e1. Reduction of Lattice Strain\u003c/b\u003e: Laser irradiation reduces the lattice strain of hydroxyapatite and decreases enamel solubility by altering the carbonate, water, and organic content of the tooth mineral phases. This process creates a morphologically hardened enamel surface that acts as a protective barrier against acid attack. Further, SEM analysis of erbium-treated enamel has revealed a smooth and glossy surface devoid of any cracks, making enamel impervious to acidic dissolution. \u003cb\u003e2. Microseive Creation\u003c/b\u003e: Laser treatment facilitates the creation of microseives, allowing the re-precipitation of mobilized calcium, phosphate, and fluoride ions during demineralization. \u003cb\u003e3. Reduction of Permeability\u003c/b\u003e: Laser irradiation reduces the permeability of the mineral structure due to protein denaturation and swelling. \u003cb\u003e4. Increased Uptake of Ions\u003c/b\u003e: The laser-altered enamel structure enhances the penetration of fluoride ions and the CCP-ACP nano-complex into the deep layers of the hydroxyapatite crystal. The increased fluoride, calcium, and phosphate mineral content in enamel enhance the laser's ability to inhibit demineralization and promote remineralization, thereby increasing SMH. \u003cb\u003e5. Formation of Surface Coating Reservoirs\u003c/b\u003e: Laser treatment creates surface coating reservoirs for calcium phosphate and fluoride. These numerous nanoclusters of fluoride, calcium, and phosphate deposits on the tooth surface can act as a reservoir to replenish the soluble calcium and phosphate ions that have diffused into the subsurface enamel. SEM studies have revealed increased deposition of spherical or globular deposits measuring 2\u0026ndash;4 \u0026micro;m in size, resembling the morphology of calcium fluoride, which acts as a reservoir of mineral ions against acid attacks. Under high-risk clinical conditions, this has a bacteriostatic or bactericidal effect on plaque microorganisms [\u003cspan additionalcitationids=\"CR36 CR37 CR38\" citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eConsistent with the findings of the present study, previous research has reported a significantly smaller reduction in SMH when lasers are used in conjunction with fluoride or CPP-ACP-containing remineralizing agents [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Therefore, in agreement with prior studies, the present study recommends the synergistic use of lasers and remineralizing agents to enhance SMH and serve as the most effective preventive measure for white spot lesions. However, contrasting findings have been reported in the literature, indicating no superiority in the SMH of primary enamel following the combined use of erbium or non-erbium lasers and remineralizing agents [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIt is important to note that due to the high absorption of erbium laser by water, laser irradiation causes micro-explosions and subsequent ablation. This leads to the formation of an irregular enamel surface that enhances plaque accumulation. Therefore, these lasers should be used under sub-ablative conditions to improve chemical alterations, reduce unwanted morphological changes of the enamel surface, and preserve the pulp from potential thermal changes [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. The highest synergistic effect was observed with the use of Er: YAG lasers in combination with varnishes, such as Fluor Protector\u0026reg; and MI Varnish\u0026reg;. This finding aligns with Babu et al., who reported a non-significant difference in SMH when treated with Fluor Protector\u0026reg; and MI Varnish\u0026reg; without laser irradiation of the enamel surface [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Consequently, varnishes containing CPP-ACP and fluoride can be effectively used as an alternative to fluoride varnish, especially since a high-fluoride strategy cannot be employed due to its adverse effects.\u003c/p\u003e \u003cp\u003eThere are inconsistencies in the literature regarding the optimal sequence for applying remineralizing agents and laser irradiation. Considering the laser's role in preserving remineralizing ions near the enamel, in the present study, laser irradiation was performed first, followed by the application of remineralizing agents, consistent with the methodology of some previous studies [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Furthermore, if remineralizing agents are applied before laser treatment, the laser may act as a barrier coat [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. According to the results of this study, the two lasers used in this study had similar effects in increasing the SMH of primary tooth enamel. This finding aligns with Hawas et al., who reported no significant difference between the two types of erbium lasers and the combination of lasers with remineralizing agents in enhancing enamel SMH [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe findings of studies examining the effects of lasers on enamel microhardness are diverse and inconclusive. Some authors suggest that laser irradiation enhances SMH, while others have reported no enhancement, and some indicate no effect on enamel [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan additionalcitationids=\"CR9 CR10 CR11\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. The discrepancies in these findings can be attributed to differences in laser types and parameters, the use of fluoride or non-fluoride remineralizing agents, demineralization methods, and SMH assessment techniques. Additional factors, such as the sequence of laser application, variations in tooth type, composition, patient age, storage medium, and study design further complicate the results [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. These variations underscore the complexity of laser effects on enamel and highlight the need for standardized laser parameters for use in primary teeth.\u003c/p\u003e \u003cp\u003eIn the current study, we endeavored to minimize confounding factors. The teeth collected were from patients within the same age range, and a remineralizing solution with controlled pH was used to simulate the oral environment. All procedures were performed by a single operator. However, since this study was conducted in in-vitro conditions, caution should be exercised when extrapolating the findings to clinical settings. Although in-vitro research offers important insights, it cannot fully replicate the complexity of the oral environment. Clinical conditions like decayed tissue, tooth anatomy diversity, chemical composition, and the physical and chemical properties of saliva such as saliva flow rate, composition, and buffering capacity can significantly influence water content, ablation thresholds, and enamel structure removal, differing greatly from the controlled settings of in-vitro studies [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Additionally, factors such as aging, occlusal forces, acid erosion, and temperature fluctuations\u0026mdash;absent in in-vitro studies\u0026mdash;play an important role in the SMH of tooth structure and should be considered in future research. Future in-vivo studies with larger sample sizes are needed to determine the optimal parameters of erbium lasers for primary teeth under various assessment methods and to identify the sequence or method of applying remineralizing agents and lasers. Additionally, the effects of heat generation by lasers on the tooth surface and dental pulp should be studied to identify the safest and most effective laser wavelength and power for clinical use.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eLaser irradiation alone increased the SMH compared to positive and negative groups of enamel surfaces.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThe application of remineralizing agents enhanced the SMH compared to baseline values, and positive and negative groups of enamel surfaces.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThe highest SMH was observed with the use of a laser in conjunction with varnish-form remineralizing agents. There was no significant difference in SMH between the use of Fluor Protector\u0026reg; and MI Varnish\u0026reg;.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eErbium laser irradiation followed by the application of remineralizing agents demonstrated a synergistic effect in increasing enamel SMH, suggesting its potential use as a preventive measure for dental caries.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of Interest\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e/Competing Interests\u003c/strong\u003e: The authors have no conflicts of interest to declare that are relevant to the content of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHuman Ethics and Consent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformed written consent was secured from the parents or legal guardians, and assent was obtained from children aged 6 years and older, permitting the use of their teeth for research purposes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical clearance to conduct this study was obtained from the Institutional Ethics Committee (IEC/HIMS/RR235). The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003enot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funds, grants, or other support was received in regard to the submitted work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGB: Conception of design, Acquisition of data, Interpretation of data, Drafting the article, Revision of article KG: Acquisition of data, Interpretation of data, Drafting the article, Revision of article GMD: Acquisition of data, Interpretation of data, Revision of articleAll authors approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data used to support the findings of this study can be made available upon request to the corresponding author.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDiaci J, Gaspirc B (2012) Review comparison of Er:YAG and Er,Cr:YSGG lasers used in dentistry. 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J Clin Diagn Res 11(9):ZC59\u0026ndash;ZC63\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZezell DM, Ana PA, Benetti C, Goulart VP, Bachmann L, Tabchoury CPM, Cury JA (2010) Compositional and crystallographic changes on enamel when irradiated by Nd:YAG or Er,Cr:YSGG lasers and its resistance to demineralization when associated with fluoride. In: Rechmann P, Fried D, editors. Lasers in Dentistry. 16th ed. Proc SPIE:1\u0026ndash;12\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu Y, Hsu CY (2007) Laser-induced compositional changes on enamel: a FT-Raman study. J Dent 35(3):226\u0026ndash;230\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUlusoy NB, Akbay Oba A, Cehreli ZC (2020) Effect of Er,Cr:YSGG Laser on the Prevention of Primary and Permanent Teeth Enamel Demineralization: SEM and EDS Evaluation. Photobiomodul Photomed Laser Surg 38(5):308\u0026ndash;315\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBevil\u0026aacute;cqua FM, Zezell DM, Magnani R, da Ana PA, Eduardo Cde P (2008) Fluoride uptake and acid resistance of enamel irradiated with Er:YAG laser. Lasers Med Sci 23(2):141\u0026ndash;147\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"701\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 701px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable-1: Materials used, and the procedure protocol followed for surface treatment of enamel\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroups\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDetails of the remineralizing agents\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEnamel surface treatment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003ePositive control\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were left untreated and did not undergo any surface modifications [5].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-2\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eNegative control\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples underwent only the demineralization-remineralization cycle [5].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-3\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\u0026nbsp;\u0026nbsp;\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr: YAG laser (Fidelis; Fotona, Medical Laser, Ljubljana, Slovenia)/(Smart 2940D plus, Deka, Calenzana, Italy)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er:YAG laser (wavelength 2.940 nm, 100 mJ pulsed energy, 1.59 J/cm\u0026sup2; energy density, 1 W power, 10 Hz frequency, 250 \u0026micro;s pulse width, 10-second duration, 1 mm spot diameter, and 50% water) using a swiping motion over the entire enamel surface in a non-contact mode. This was achieved by attaching an endodontic file to the handpiece, maintaining a 1 mm distance from the enamel surface [15].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-4\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG laser (Water Lase MD System, BioLase Technology Inc., San Clemente, CA, USA)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er,Cr:YSGG laser (wavelength 2.780 nm, 1.5 W, 35 mJ energy per pulse, and 17.8 J/cm\u0026sup2; energy density). The laser was directed over the entire enamel surface in a non-contact mode using a turbo handpiece with an MX5 short insert (0.5 mm diameter) at 20 Hz frequency under an air/water spray (40% air, 60% water). The non-contact mode was ensured by attaching an endodontic file to the handpiece, maintaining a 1 mm distance from the enamel surface [5,6].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eFluorovil\u0026reg; (Vishal Dentocare Pvt.Ltd., India)\u003c/p\u003e\n \u003cp\u003e(Acidulated phosphate fluoride gel)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eFluorovil\u0026reg; gel was applied to the enamel samples for 4 minutes using a cotton swab, then removed with gauze. The specimens were washed with deionized water for 1 minute. Following this, the enamel specimens were stored in deionized water for 24 hours and subsequently subjected to a 7-day demineralization-remineralization cycle [5,15].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eFluor Protector\u0026reg; varnish (Ivoclar Vivadent, Amherst, N. J, USA)\u003c/p\u003e\n \u003cp\u003e(Fluoride in varnish form)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eA thin layer of Fluor Protector\u0026reg; varnish was applied to the enamel surface according to the manufacturer\u0026apos;s instructions, using the provided soft-bristled applicator tip. After 24 hours, the varnish was carefully removed from the enamel samples using cotton swabs soaked in acetone, and the specimens were then washed with deionized water for 1 minute. Subsequently, the specimens were stored in deionized water for 24 hours and then subjected to a 7-day demineralization-remineralization cycle [5,7].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eMI Paste\u0026reg; (GC India Dental Pvt Ltd., India\u003c/p\u003e\n \u003cp\u003e(Casein phosphopeptide-amorphous calcium phosphate paste)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were treated with MI Paste\u0026reg; using an applicator tip and left for 3 minutes. They were then cleaned with cotton rolls and washed with deionized water for 1 minute. After this, the specimens were stored in deionized water for 24 hours and subsequently subjected to a 7-day demineralization-remineralization cycle. The application of MI Paste\u0026reg; was repeated daily at the same time throughout the 7-day cycle [4,5].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eMI Paste Plus\u003csup\u003e\u0026reg;\u0026nbsp;\u003c/sup\u003e(GC India Dental Pvt Ltd., India\u003c/p\u003e\n \u003cp\u003e(Casein phosphopeptide-amorphous calcium phosphate paste+ fluoride)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were treated with MI Paste Plus\u0026reg; using an applicator tip and left for 3 minutes. They were then cleaned with cotton rolls and washed with deionized water for 1 minute. Following this, the specimens were stored in deionized water for 24 hours and subsequently subjected to a 7-day demineralization-remineralization cycle. The application procedure of MI Paste Plus\u0026reg; was repeated daily at the same time throughout the 7-day cycle [18].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eMI varnish\u003csup\u003e\u0026reg;\u003c/sup\u003e (GC India Dental Pvt Ltd., India) (Casein phosphopeptide-amorphous calcium phosphate paste+ fluoride)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were treated with MI Varnish\u0026reg; using the manufacturer\u0026apos;s provided applicator tip. After 24 hours, the varnish was carefully removed from the enamel samples using cotton swabs soaked in acetone, and then the specimens were washed with deionized water for 1 minute. Following this, the specimens were stored in deionized water for 24 hours and subsequently subjected to a 7-day demineralization-remineralization cycle [7].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr: YAG + \u0026nbsp;Fluorovil\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of Fluorovil\u0026reg; gel as described above [5,15].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr: YAG + \u0026nbsp;Fluor Protector\u0026reg; varnish\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of Fluor Protector\u0026reg; varnish as previously described [7,15].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr: YAG + MI Paste\u0026reg;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of MI Paste\u0026reg; as described earlier[5,15].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr: YAG + \u0026nbsp;MI Paste Plus\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of MI Paste Plus\u0026reg; as described earlier[15,18].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr: YAG + \u0026nbsp;MI Varnish\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er:YAG laser according to the previously mentioned specifications, followed by the application of MI Varnish\u0026reg; as described earlier [7,15].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG + \u0026nbsp;Fluorovil\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of Fluorovil\u0026reg; gel as described earlier [5,6].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG + \u0026nbsp;Fluor Protector\u0026reg; varnish\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of Fluor Protector\u0026reg; varnish as described earlier [5,7].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG + \u0026nbsp;MI Paste\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of MI Paste\u0026reg; as described earlier [5].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG + \u0026nbsp;MI Paste Plus\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of MI Paste Plus\u0026reg; as described earlier [5,18].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eGroup-19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 172px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG+ MI Varnish\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 473px;\"\u003e\n \u003cp\u003eThe enamel samples were irradiated with an Er,Cr:YSGG laser according to the previously mentioned specifications, followed by the application of MI Varnish\u0026reg; as described earlier [5,7].\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"756\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"12\" valign=\"top\" style=\"width: 756px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTABLE -2: Comparison of mean surface microhardness of enamel between different groups at baseline, after treatment and after pH cycle using One-way ANOVA Test\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 199px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroups\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBaseline-A\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAfter treatment-B\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAfter\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eDemineralization-Remineralization\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;cycle-C\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eB-A\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(\u0026Delta;1)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eC-B\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(\u0026Delta;2)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eC-A\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(\u0026Delta;3)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003ePositive control\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e305.15\u0026plusmn;33.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eNegative control\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e305.80\u0026plusmn;25.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e199.05\u0026plusmn;6.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-106.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eOnly Er:YAG laser\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e298.45\u0026plusmn;29.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e386.90\u0026plusmn;16.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e281.95\u0026plusmn;14.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e88.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-104.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-16.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eOnly Er,Cr:YSGG\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e306.60\u0026plusmn;21.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e375.95\u0026plusmn;16.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e259.00\u0026plusmn;15.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e69.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-116.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-47.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eFluorovil\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e353.45\u0026plusmn;18.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e381.75\u0026plusmn;7.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e269.60\u0026plusmn;7.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e28.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-112.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-83.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eFluor Protector\u0026reg;\u0026nbsp;Varnish\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e315.50\u0026plusmn;31.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e417.60\u0026plusmn;13.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e383.85\u0026plusmn;5.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e102.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-33.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e68.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eMI Paste\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e310.35\u0026plusmn;28.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e395.65\u0026plusmn;11.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e332.20\u0026plusmn;11.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e85.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-63.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e0.01*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e21.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eMI Paste Plus\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e337.60\u0026plusmn;30.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e404.25\u0026plusmn;12.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e366.35\u0026plusmn;23.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e66.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-37.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e28.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e0.01*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eMI Varnish\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e335.60\u0026plusmn;15.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e444.45\u0026plusmn;10.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e393.15\u0026plusmn;10.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e108.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-51.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e57.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr:YAG+ Fluorovil\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e321.35\u0026plusmn;26.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e409.95\u0026plusmn;10.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e303.00\u0026plusmn;11.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e88.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-106.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e0.02*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e18.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr:YAG+ Fluor Protector\u0026reg;\u0026nbsp;Varnish\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e313.10\u0026plusmn;35.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e462.10\u0026plusmn;86.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e418.40\u0026plusmn;4.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e149.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-43.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e105.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr:YAG+MI Paste\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e328.95\u0026plusmn;32.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e435.30\u0026plusmn;18.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e390.45\u0026plusmn;15.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e106.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-44.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e61.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr:YAG+MI Paste Plus\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e334.95\u0026plusmn;21.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e476.65\u0026plusmn;13.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e397.50\u0026plusmn;18.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e141.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-79.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e62.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr:YAG+MI Varnish\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e338.60\u0026plusmn;34.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e476.45\u0026plusmn;15.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e404.90\u0026plusmn;19.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e137.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-71.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e66.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG+ Fluorovil\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e308.75\u0026plusmn;42.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e391.90\u0026plusmn;11.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e293.15\u0026plusmn;10.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e83.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-98.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-15.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG+ Fluor Protector\u0026reg; \u0026nbsp;Varnish\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e311.35\u0026plusmn;19.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e478.00\u0026plusmn;8.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e386.85\u0026plusmn;8.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e166.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-91.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e75.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG+MI Paste\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e317.15\u0026plusmn;27.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e418.85\u0026plusmn;8.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e355.80\u0026plusmn;5.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e101.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-63.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e38.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG+MI Paste \u0026nbsp;Plus\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e314.45\u0026plusmn;18.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e448.35\u0026plusmn;12.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e383.95\u0026plusmn;8.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e133.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-64.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e69.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34px;\"\u003e\n \u003cp\u003eG-19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 164px;\"\u003e\n \u003cp\u003eEr,Cr:YSGG+MI Varnish\u0026reg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 82px;\"\u003e\n \u003cp\u003e333.95\u0026plusmn;31.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e473.05\u0026plusmn;8.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e399.45\u0026plusmn;12.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e139.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e-73.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e65.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"11\" valign=\"top\" style=\"width: 755px;\"\u003e\n \u003cp\u003e*Stastically significant using One-way ANOVA Test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"lasers-in-medical-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"lims","sideBox":"Learn more about [Lasers in Medical Science](https://link.springer.com/journal/10103)","snPcode":"10103","submissionUrl":"https://submission.springernature.com/new-submission/10103/3","title":"Lasers in Medical Science","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Deciduous/primary teeth ·enamel, erbium Laser, surface microhardness","lastPublishedDoi":"10.21203/rs.3.rs-5727275/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5727275/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo evaluate the synergistic effect of erbium laser irradiation and remineralizing agents on the surface microhardness of primary tooth enamel.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA total of 380 primary molars were collected. Teeth were embedded in acrylic resin such that only their buccal surface were exposed. The initial surface microhardness (SMH) was measured and the teeth were allocated into 19 groups: Group-1-Positive control, Group-2-Negative control, Group-3-Er: YAG laser, Group-4- Er,Cr:YSGG laser, Group-5-Fluorovil\u0026reg;, Group-6-Fluor Protector\u0026reg; varnish, Group-MI Paste\u0026reg;, Group-8-MI Paste Plus\u0026reg;, Group-9-MI varnish\u0026reg;, Group-10-Er: YAG\u0026thinsp;+\u0026thinsp;Fluorovil\u0026reg;, Group-11-Er: YAG\u0026thinsp;+\u0026thinsp;Fluor Protector\u0026reg; varnish, Group-12-Er: YAG\u0026thinsp;+\u0026thinsp;MI Paste\u0026reg;, Group-13-Er: YAG\u0026thinsp;+\u0026thinsp;MI Paste Plus\u0026reg;, Group-14-Er: YAG\u0026thinsp;+\u0026thinsp;MI Varnish\u0026reg;, Group-15-Er,Cr:YSGG\u0026thinsp;+\u0026thinsp;Fluorovil\u0026reg;, Group-16-Er,Cr:YSGG\u0026thinsp;+\u0026thinsp;Fluor Protector\u0026reg; varnish, Group-17-Er,Cr:YSGG\u0026thinsp;+\u0026thinsp;MI Paste\u0026reg;, Group-18-Er,Cr:YSGG\u0026thinsp;+\u0026thinsp;MI Paste Plus\u0026reg; and Group-19-Er,Cr:YSGG\u0026thinsp;+\u0026thinsp;MI Varnish\u0026reg;. After the planned enamel surface treatments, a second SMH measurement was taken. The samples were then subjected to a demineralization-remineralization cycle, followed by a third SMH measurement.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe highest SMH after the demineralization-remineralization cycle was recorded with the use of Er: YAG laser in combination with Fluor Protector\u0026reg; varnish (Group 11) (418.40\u0026thinsp;\u0026plusmn;\u0026thinsp;4.17), while the lowest value was seen with the use of Er, Cr: YSGG laser alone (Group 4) (259\u0026thinsp;\u0026plusmn;\u0026thinsp;15.53).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe results indicate that erbium laser irradiation, followed by the application of remineralizing agents, has a synergistic effect in increasing enamel SMH. This suggests the potential use of such treatments as a preventive measure for dental caries.\u003c/p\u003e","manuscriptTitle":"Synergistic effect of laser irradiation and remineralizing agents on surface microhardness of primary tooth enamel -An in-vitro study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-08 18:16:55","doi":"10.21203/rs.3.rs-5727275/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-03-05T20:10:13+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-03-03T21:12:02+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-11T08:43:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"154427019729917798738921302239598888571","date":"2025-02-11T06:27:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"83403122837490267157262884224850230848","date":"2025-02-11T00:50:27+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-01-17T11:10:43+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-15T03:54:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-06T14:14:49+00:00","index":"","fulltext":""},{"type":"submitted","content":"Lasers in Medical Science","date":"2024-12-28T17:32:57+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"lasers-in-medical-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"lims","sideBox":"Learn more about [Lasers in Medical Science](https://link.springer.com/journal/10103)","snPcode":"10103","submissionUrl":"https://submission.springernature.com/new-submission/10103/3","title":"Lasers in Medical Science","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"b1b1dacf-29ae-4f07-b466-3277ab6100c2","owner":[],"postedDate":"January 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-04-21T15:58:42+00:00","versionOfRecord":{"articleIdentity":"rs-5727275","link":"https://doi.org/10.1007/s10103-025-04451-6","journal":{"identity":"lasers-in-medical-science","isVorOnly":false,"title":"Lasers in Medical Science"},"publishedOn":"2025-04-15 15:57:01","publishedOnDateReadable":"April 15th, 2025"},"versionCreatedAt":"2025-01-08 18:16:55","video":"","vorDoi":"10.1007/s10103-025-04451-6","vorDoiUrl":"https://doi.org/10.1007/s10103-025-04451-6","workflowStages":[]},"version":"v1","identity":"rs-5727275","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5727275","identity":"rs-5727275","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}