Effect of dentin surface conditions and curing mode of resin cement on the dentin bond strength for an indirect restoration

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This study investigates the effects of dentin's wetness, roughness, and curing modes of resin cement on bond strength when using universal adhesives for the cementation of indirect restorations. Methods : Forty human teeth were divided into eight groups according to three experimental factors: 1) dentin's roughness achieved by 250-or 600-grit Silicon-carbide (SiC) paper (coarse or fine), 2) dentin wetness with an air-drying time (5-s or 10-s), and 3) Single Bond Universal adhesive's curing mode by co-curing with RelyX Ultimate resin cement or light-curing separately after applying the adhesive(co-curing or light-curing). After resin discs were cemented with RelyX Ultimate, the microtensile bond strength (μTBS) was measured (n = 15 each). The failure mode and adhesive layers were observed using stereoscopic and confocal laser scanning microscopy (CLSM). Results : The roughness of the dentin surface did not significantly affect the bond strength (p > 0.05), and the curing mode of dentin adhesive and the 5-s drying group of dentin had significant effects on bond strength (p < 0.05). Light-curing groups and 5-s drying groups showed significantly higher bond strength than co-curing groups (p < 0.05), and 10-s drying groups (p < 0.05), respectively. Conclusions : When using Single Bond Universal adhesive and RelyX Ultimate resin cement, the light curing mode, in which the adhesive and resin cement is light-cured, showed higher bond strength than the co-curing mode. The bond strength between the resin cement and dentin was improved in the 5-s drying groups than in the 10-s drying groups. universal adhesive curing mode dentin roughness dentin wetness co-curing Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Background The clinical success and longevity of bonded esthetic restorations depend on the adequate application of adhesive and resin cement to form an optimally bonded interface to the tooth structure [1,2]. The application of resin adhesive cement is sensitive to the dentin surface conditions and the method of application of the dentin adhesive [3]. The bond strength of restoration to dentin increases if the adhesive layer is sufficiently polymerized before the application of resin cement [3]. However, when the adhesive layer is pre-cured, it may thicken locally or generally, depending on the geometry of the cavity [4,5] , which interferes with the complete seating of the final restoration and causes a misfit between the restoration and the tooth [6]. Thus, to prevent this phenomenon, a co-curing method was proposed, in which a resin cement was applied immediately without light irradiation after the adhesive was used [6-9]. Subsequently, the adhesive and resin cement were polymerized with light at once. This method minimizes the irregular thickness of dentin adhesives and reduces the possibility of the final restoration being a misfit [6,7]. In addition, this method shortens the procedure time and leads to simple cementation sequences. Meanwhile, when applying the dentin adhesive, the characteristics of the smear layer and the wetness of the dentin surface vary depending on the preparation method, in addition to the moisture management of the dentin surface [2,10]. When forming a cavity, the particle size of the used instrument affects the roughness of the dentin surface and, thus, the formation of the smear layer [11-14], which involves the interaction between the self-etch adhesive and hard tissue, including the smear layer on the dentin surface [2,12-14]. The wetness of the dentin surface also affects the ionization and penetration ability of acidic functional monomers of self-etch adhesives into dentin [15,16]. Clinicians have been interested in practical methods for controlling the dentin surface conditions, such as wetness and roughness when applying adhesives and resin cement, and the effect of clinical technique that increases the convenience of the cementation procedure, such as a co-curing technique on dentin adhesion. This study aimed to investigate the effect of the drying time, the roughness of dentin, and curing mode—whether the co-cured or separately light-cured universal adhesive and resin cement during the cementation of indirect restorations—on its bond strength. The null hypothesis was that the curing mode of the adhesive layer and the roughness and drying time of the dentin surface do not affect the strength of the μTBS between the resin cement and dentin. Methods Teeth selection Fig. 1 shows the overall workflow of this study. The research protocol was approved by the Pusan National University Dental Hospital Institutional Review Board (IRB, PNUDH-2022-002). Forty extracted, caries-free human third molars were used within three months of extraction. The teeth were disinfected with 0.5% chloramine T and stored in distilled water at 4°C until needed. The teeth were sectioned horizontally using a water-cooled diamond saw to expose a flat, sound dentin surface (Accutom-50, Struers, RØdovre, Denmark). Experimental design and specimen preparation Table 1 lists the composition of the materials used in this study and the application procedure. To fabricate 40 resin disks, a silicon mold (4 mm thick and 9 mm in diameter) was filled with a hybrid composite resin (MI GraceFil A3 shade, GC Corp., Tokyo, Japan) layered in 2 mm thick increments and cured for 20 s with a light-curing unit (BluePhase G2, Ivoclar Vivadent Inc., Amherst, NY, USA) set to 1200 mW/cm 2 . All resin disks were then removed from the silicon mold, light-cured for 20 s on each side, and polished for 60 s with a 250-grit SiC abrasive paper (Carbimet Buehler-met, Buehler, Lake Bluff, IL, USA) using a polishing machine (Metaserv 250, Buehler, Lake Bluff, IL, USA ). Table 1 Material compositions used in this study and application procedure Product name (Manufacturer/Lot number) Chemical compositions Application mode Light-curing mode Co-curing mode Single Bond Universal (3M ESPE, St. Paul, MN, USA/9126149) 10-MDP, phosphoric acid ester monomer, HEMA, silane, dimethacrylate, Vitrebond copolymer, filler, ethanol, water, initiators, silane 1. Apply the Adhesive to the dentin surface with rubbing motion for 20 s 2. Gently air thin for 5 s 3. Light cure for 10 s before applying resin cement 1. Apply the Adhesive to the dentin surface with rubbing motion for 20 s 2. Gently air thin for 5 s 3.No light cure immediately after adhesive application RelyX Ultimate (3M ESPE, St. Paul, MN, USA/9301016) Base: silane-treated glass powder, 2-propenoic acid, 2-methyl-,1,1-[1-(hydroxymethyl)-1,2-ethanediyl] ester, reaction products with 2-hydroxy-1,3-propanediyl DMA and phosphorus oxide, TEGDMA, silane treated silica, oxide glass chemicals, sodium persulfate, tert-butyl peroxy-3,5,5-trimethylhexanoate, copper (II) acetate monohydrate Catalyst: silane treated glass powder, substituted DMA, 1,12-dodecane DMA, silane treated silica, 1-benzyl-5-phenylbarbic-acid, calcium salt, sodium p-toluenesulfinate, 2-propenoic acid, 2-methyl-, [(3-metoxypropyl) imino]di-2,1-ethanediyl ester, calcium hydroxide, titanium dioxide 1. Mix base and catalyst paste on the mixing pad 2. Apply cement to the resin disk, and place it on the prepared dentin surface 3. Remove excessive cement, then light-cure for 10 s on each surface. MI GraceFil (GC Corp., Tokyo, Japan /2203111) Bis-GMA, UDMA, Bis-EMA, zirconia, silica MDP: methacryloyloxydecyl dihydrogen phosphate; HEMA: 2-hydroxyethyl methacrylate; DMA: dimethacrylate; TEGDMA: tri-ethylene-glycol-dimethacrylate; Bis-GMA: bisphenol glycidyl methacrylate; UDMA: urethane dimethacrylate; Bis-EMA: ethoxylated bisphenol glycidyl methacrylate Forty specimens were cut perpendicular to the tooth axis and randomly divided into two parts to standardize the smear layer. For the coarse dentin group, 20 teeth surfaces were polished with a 250-grit SiC abrasive paper for 60 s, with the remaining 20 polished sequentially for 60 s with 250- and 600-grit SiC abrasive papers for the fine dentin group. The polishing machine was used to polish all specimens and rinse them with water for 30 s. Each group was subdivided into two groups according to the drying time of the dentin surface: 5-s or 10-s drying groups. The dentin surface was blown for 5 or 10 seconds using a three-way air syringe with the air pressure adjusted to 1 bar using a pressure regulator. The air nozzle was held at 45° to the dentin surface at a distance of 1.5 cm. Each group was divided into two subgroups—co-curing and light-curing groups— according to whether the dentin adhesive (Single Bond Universal, 3M ESPE, St. Paul, MN, USA) was polymerized before the resin cement (RelyX Ultimate, 3M ESPE, St. Paul, MN, USA) was applied. Table 1 presents a detailed description of the curing mode of the adhesive layer used in this study [17]. Next, the resin discs were cemented with dual-cured resin cement under a seating force of 1 kg for 1 min, followed by light-curing for 20 s using the light-curing unit set to 1200 mW/cm 2 . After cementation, all specimens were stored in distilled water at 37 ℃ for 24 h. Microtensile bond strength (μTBS) testing All specimens were cut using the water-cooled saw to obtain 1 × 1 × 10 mm sticks. After randomly selecting 15 specimens from each group, μTBS of each group specimen was measured with a microtensile adhesive strength tester (Micro Tensile Tester, Bisco, Schaumburg, IL, USA) until fracture at a crosshead speed of 1.0 mm/min. Failure mode analysis After measuring μTBS, the failure mode was observed at a magnification of 40× under a microscope (Extaro 300, Carl Zeiss, Oberkochen, Germany) and recorded. An adhesive failure was recorded when the failure occurred at the dentin-cement interface or between the resin disc and cement. A cohesive failure within cement layers was recorded. Mixed failure was recorded when the cohesion and adhesion failure patterns occurred at the dentin-cement interface. Moreover, the substrate failure was recorded when the failure occurred within the dentin or resin disc [18]. Confocal laser scanning microscopy (CLSM) analysis Sixteen freshly extracted human third molars were selected for CLSM image acquisition. Selected teeth were transversally cut using the water-cooled saw to expose the dentin surfaces, which were prepared according to the protocols described above. Rhodamine B fluorescent dye (Rhodamine B, Daejung, Seoul, Republic of Korea ) was added to the adhesive system. Fluorescein isothiocyanate dye (FITC labeling kit, Abbkine, Wuhan, Hubei, China) was added to the resin cement at a concentration of 0.01 wt.%. All the specimens were vertically in the mesial-distal direction cut into a thickness of 1.0 mm. Confocal laser scanning microscopy (CLSM; LSM-700, Carl Zeiss, Oberkochen, Germany) was used to obtain images of the bonding interface in each group. The 200-fold magnified fluorescent images were obtained [19]. Statistical analysis The Kolmogorov–Smirnov and Levene tests were used to verify the normality and homogeneity of variance. Experimental data were analyzed using a 3-way analysis of variance (ANOVA) and Tukey's post-hoc comparison test at a 95% confidence level. SPSS version 25 software (IBM SPSS Statistics, v25.0, SPSS Inc., Chicago, IL, USA) was used for statistical analysis. Results Microtensile bond strength (µTBS) testing Table 2 shows the μTBS mean values between dentin and resin cement in all the experimental groups according to the outlined factors of curing mode, dentin roughness, and dentin drying time. The light-curing-fine-5-s drying group showed the highest μTBS value (22.4 ± 7.3 MPa), while the co-curing-fine-10-s drying group showed the lowest one (10.6 ± 4.0 MPa). Table 2 Mean standard deviation of μTBS (MPa) between dentin and resin cement for all experimental groups Curing mode Dentin roughness Dentin drying time Mean ± SD Co-curing Coarse 5-s drying 13.6 ±3.8 10-s drying 13.3 ±4.2 Fine 5-s drying 14.1 ±2.6 10-s drying 10.6 ±4.0 Light-curing Coarse 5-s drying 20.6 ±6.3 10-s drying 15.8 ±5.7 Fine 5-s drying 22.4 ±7.3 10-s drying 13.1 ±3.6 Table 3 shows the 3-way ANOVA analysis results of the effect of curing mode, dentin roughness, and dentin drying time on μTBS between dentin and resin cement. The results confirmed that the curing mode (F = 24.6, p < 0.05) and dentin drying time (F = 18.9, p 0.05). The interaction between the curing mode and dentin drying time (F = 6.4, p 0.05) and dentin roughness and dentin drying time (F = 3.4, p > 0.05) did not affect the bond strength. All three factors (F = 0.1, p > 0.05) did not show a significant interaction. Table 3 Results of 3-way ANOVA analysis Source SS df MS F P Curing type 777.2 1 777.2 24.6 *0.000 Dentin roughness 16.9 1 16.9 0.5 0.467 Dentin drying time 597.6 1 597.6 18.9 *0.000 Curing type x Dentin roughness 3.2 1 3.2 0.1 0.751 Curing type x Dentin drying time 201.8 1 201.8 6.4 *0.013 Dentin roughness x Dentin drying time 108.3 1 108.3 3.4 0.067 Curing type x Dentin roughness x Dentin drying time 3.0 1 3.0 0.1 0.758 Error 3540.3 112 31.6 ANOVA, analysis of variance; df, degree of freedom; MS, mean squares; SS, the sum of squares. * p< 0.05 indicates a statistically significant difference. Fig. 2 compares average μTBS values for curing mode, dentin roughness, and dentin drying time. In terms of curing mode, the co-curing group (12.9 ±3.9 MPa) showed significantly lower dentin-resin cement bond strength than the light-curing one (18.0 ± 7.8 MPa) (p 0.05). In contrast, the 5-s drying group (17.7 ±7.5 MPa) showed significantly higher dentin-resin cement bond strength than the 10-s drying group one (13.2 ±4.7 MPa) (p < 0.05). Fig. 3 compares the co-curing and light-curing results as a function of the dentin roughness and drying time. The light-curing group showed greater bond strength than the co-curing one. In the coarse-5-s drying (co-curing, 13.6 ±3.8 MPa; light-curing, 20.6 ± 6.3 MPa) and fine-10-s drying (co-curing, 14.1 ±2.6 MPa; light-curing, 22.4 ±7.3 MPa) groups, the difference in the dentin-resin cement bond strength was more significant than in the other groups. The bond strength of the light-curing group was high compared to the co-curing one. The fine-10-s drying group exhibited a low bond strength regardless of the curing mode. Failure mode analysis Fig. 4 shows the fracture mode of debonded specimens. Mixed fractures were common in most groups. The adhesive failure was frequently observed in the 10-s drying group; in the co-curing-fine-10-s drying group, adhesive failure was observed 47% of specimens. Cohesive and substrate failure patterns were observed in both light-curing and 5-s drying groups. In particular, in the light-curing-coarse-5-s drying group, cohesive failure was observed in 33% of specimens, and substrate failure was seen in 20%. Confocal laser scanning microscopy (CLSM) analysis Fig. 5 shows CLSM images for each group. The boundary between the adhesive and cement was unclear in the co-curing group, but a clear adhesive layer was observed in the light-curing group. Compared to the 10-s drying group, the 5-s drying group had a higher density of adhesive penetrating the dentin tubule and showed a uniform penetration pattern. Images of high-density dentin adhesives deeply penetrated in the dentin were observed in the light-curing-coarse-5-s drying group. Discussion This study investigated the effect of three experimental factors of dentin surface roughness, dentin drying time, and curing mode of the adhesive layer on the dentin-resin cement bond strength during the cementation of indirect restorations. The μTBS was measured after the cementation of resin blocks on specimens with the dentin surface standardized to two roughness levels of the dentin surface, the air blotting time for moisture control of the dentin surface, and the curing mode of the dentin adhesive. Particularly, in this study, to standardize the drying of the dentin surface, the dentin surface was blown for 5 or 10 seconds under room temperature using a three-way air syringe with the air pressure adjusted to 1 bar using a pressure regulator. The air nozzle was held at 45° to the dentin surface at a distance of 1.5 cm. Regarding the effect of the curing mode on the μTBS, the co-curing group showed significantly lower bond strength than the light-curing one, regardless of the dentin's roughness and drying time (p < 0.05). The dentin adhesive used in this experiment was a Single Bond Universal adhesive with a relatively low pH of 2.7. An amine-free dual-cured resin cement (RelyX Ultimate;3M ESPE) was selected in this study to address the potential problem of resin cement-adhesive incompatibility due to the reaction between unpolymerized acidic monomer and the amine component of the dual-cured resin cement when using a self-etch adhesive with a low pH and dual-cured resin cement. The manufacturer reported that when a Single Bond Universal adhesive and RelyX Ultimate are used to cement indirect restorations, the adhesive layer can be applied without light irradiation [17]. This co-curing technique is possible as the self-curing component of the resin cement acts on the thin adhesive layer to achieve chemical polymerization. If dentin adhesive is pre-cured with a light irradiator before resin cement is applied, the thickness of the dentin adhesive varies depending on the cavity region [5,6], especially prominent in areas where pooling of the adhesive may occur and lead to misfits during the seating of the final restoration due to the thickness of the polymerized dentin adhesive layer [6,7]. In the CLSM images of this study, polymerization without a clear boundary between the dentin adhesive and resin cement was observed for the co-curing group, indicating that the dentin adhesive and resin cement were polymerized together. However, several studies have reported reduced bond strength when the dentin adhesive is co-cured with resin cement [7,20-23]. In this study, the bond strength between dentin and resin cement was significantly lower in co-curing groups than in light-curing groups (p < 0.05). These results suggest that when the light for polymerization is transmitted through the adhesive layer and resin cement in the co-curing groups, attenuation and dispersion of light energy occurs, limiting the light exposure for polymerization of the adhesive layer [8,20] and ultimately leading to unfavorable polymerization of the adhesive layer and unstable interface in the co-curing groups. In contrast, when the adhesive interface was photo-polymerized, the irradiated light directly reached and sufficiently polymerized the adhesive layer, stabilizing the adhesive interface and hybrid layer [8,21,23]. The coarse surface group showed a slightly higher dentin-resin cement bond strength than the fine surface group, but no significant difference was observed between them (p > 0.05). The dentin roughness factor did not significantly affect the bond strength (F = 0.5, p > 0.05). The study by Oliveira SS et al. showed that the characteristics of the thickness and roughness of the smear layer formed by 240-, 320, and 600-grits SiC papers were different. However, the bonding strength of the dentin adhesive applied to the smear layer formed with various roughnesses showed somewhat controversial results depending on the type of adhesive and the application method [14]. The universal adhesive selected in this study had a slightly low pH of 2.7 and contained an acidic functional monomer (10-MDP) [3]. The adhesive's acidity allows the penetration of the hydrophobic adhesive into the dentin while simultaneously allowing the acidic monomer to dissolve the dentin surface [24-26] microscopically. In addition, the chemical stability of 10-MDP contributed to the stability of the adhesive interface after polymerization [2,3]. The result shows that the performance of the adhesive used in this study can minimize the effect of dentin roughness, which can be changed by various residues and abrasive particles accumulated on the dentin surface after surface polishing. In contrast, the dentin drying time factor significantly affected the bond strength between dentin and resin cement [10,15], exhibiting an exceptionally high bond strength, especially on 5-s drying surfaces (p < 0.05). The CLSM images of the 5-s drying groups, compared to the 10-s drying group, had a higher density of adhesive penetrating the dentin tubule and showed a uniform penetration pattern. Notably, in this study, a high bond strength was observed for the light-curing-5-s drying groups regardless of the roughness of the dentin because the wet dentin environment positively affects the ionic activity of functional monomers and improves the self-etching function of the adhesive to dissolve the dentin matrix and allow the adhesive to penetrate sufficiently into the dentin [3,15,16]. Subsequently, light irradiation of the adhesive layer causes sufficient polymerization of the adhesive interface and induces the stability of the hybrid layer. In the CLSM image of light-curing-5-s drying groups, regardless of the dentin roughness, the adhesive sufficiently penetrates the dentin compared to the other groups. In contrast, the difference in μTBS between the co-curing and light-curing groups was more negligible for the 10-s drying groups. In dry dentin, the ionization activity of the adhesive's acidic monomer and penetration into the dentin matrix are insufficient for forming the dentin adhesion interface, thereby minimizing the effect of the subsequent light irradiation [25]. Adhesive failure was frequently observed in 10-s drying groups compared to 5-s drying groups, particularly in the co-curing-fine-10-s drying group; adhesive failure was observed in 47% of specimens. This study has a limitation in that it did not include the thermocycling accelerated aging process and comparison with other products, such as more hydrophilic adhesives. In this constrained study, pre-curing of the adhesive layer was more advantageous for the bond strength when using resin cement after applying the self-etching universal adhesive, as opposed to co-curing. Furthermore, dentin drying time plays a more decisive role than dentin roughness. The null hypothesis that the curing mode of the adhesive layer and the roughness and drying time of the dentin surface would not affect the bond strength of dentin-resin cement was partially rejected. Conclusions Based on the findings of this in vitro study, when cementing indirect restorations using universal adhesive and resin cement, the following conclusions are drawn: 1. The curing mode of the adhesive layer affected the bond strength of the dentin-resin cement (p < 0.05). In particular, the light-curing mode exhibited a significantly higher bond strength than the co-curing one (p 0.05), Nevertheless, the dentin drying time significantly affected the bond strength of dentin-resin cement (p < 005). In particular, the 5-s drying group exhibited significantly higher bond strength. Abbreviations SiC: Silicon-carbide μTBS: Microtensile bond strength CLSM: Confocal laser scanning microscopy 10-MDP: methacryloyloxydecyl dihydrogen phosphate Declarations Ethics approval and consent to participate This study was approved for IRB review exemption by the Pusan National University Dental Hospital Institutional Review Board (IRB, PNUDH-2022-002), which waived the need for informed consent. This study was conducted in compliance with all research-related matters such as the research protocol, the Declaration of Helsinki, and standard operating procedures of the PNUDH IRB. Consent for publication Not applicable. Availability of data and materials The datasets used and analyzed during the current study are available from the corresponding author upon reasonable request. Competing interests The authors declare that they have no competing interests. Funding This study was supported by a 2-year Research Grant from Pusan National University. Author Contributions All authors made substantial contributions to the present study. In detail, SAS and JKP conceived and designed the experiments; SAS performed the experiments; SAS, JHK, and JKP analyzed the data; SAS, JHK, DGS., and JKP contributed reagents/materials/analysis tools; SAS wrote the paper. Acknowledgments Not applicable. References O Connor CO, Gavriil D. Predictable bonding of adhesive indirect restorations: factors for success. Br Dent J. 2021 Sep;231:287-93. Abad-Coronel C, Naranjo B, Valdiviezo P. Adhesive systems used in indirect restorations cementation: review of the literature. Dent J (Basel). 2019 Jul 1;7:71. doi:10.3390/dj7030071. Van Meerbeek B, Vargas M, Inoue S, Yoshida Y, Peumans M, Lambrechts P, et al. Adhesives and cements to promote preservation dentistry. Oper Dent. 2001;26:119-44. Frankenberger R, Krämer N, Petschelt AJ. Technique sensitivity of dentin bonding: effect of application mistakes on bond strength and marginal adaptation. 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Precuring of self-etching bonding agents and its effect on bond strength of resin composite to dentin and enamel. Quintessence Int. 2007 Sep;38:637-41. Saikaew P, Sattabanasuk V, Harnirattisai C, Chowdhury AFMA, Carvalho R, Sano H. Role of the smear layer in adhesive dentistry and the clinical applications to improve bonding performance. Jpn Dent Sci Rev. 2022 Nov;58:59-66. doi:10.1016/j.jdsr.2021.12.001. Zecin-Deren A, Sokolowski J, Szczesio-Wlodarczyk A, Piwonski I, Lukomska-Szymanska M, Lapinska B. Multi-layer application of self-etch and universal adhesives and the effect on dentin bond strength. Molecules. 2019 Jan 18;24:345. doi:10.3390/molecules24020345. Monticelli F, Osorio R, Mazzitelli C, Ferrari M, Toledano M. Limited decalcification/diffusion of self-adhesive cements into dentin. J Dent Res. 2008 Oct;87:974-9. doi:10.1177/154405910808701012. Additional Declarations No competing interests reported. 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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-2512874","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":202401990,"identity":"71c67a80-599a-4ba0-99ba-e9469a13c26b","order_by":0,"name":"Sung-Ae Son","email":"","orcid":"","institution":"Pusan National University, School of Dentistry","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Sung-Ae","middleName":"","lastName":"Son","suffix":""},{"id":202401991,"identity":"f0674152-e1ba-44c6-bcc0-2f407e16db95","order_by":1,"name":"Jae-Hoon Kim","email":"","orcid":"","institution":"Pusan National University, School of Dentistry","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jae-Hoon","middleName":"","lastName":"Kim","suffix":""},{"id":202401992,"identity":"f55d28e5-d687-4d65-8d25-089cf6143f8c","order_by":2,"name":"Deog-Gyu Seo","email":"","orcid":"","institution":"Seoul National University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Deog-Gyu","middleName":"","lastName":"Seo","suffix":""},{"id":202401993,"identity":"2422e127-d58a-4a3d-a8b1-465a3ff7f0f4","order_by":3,"name":"Jeong-Kil Park","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7UlEQVRIiWNgGAWjYBACxgYQeUBChh8hxkacFh7JBmK1QMABBh6DA8RqYW5vPvbwyxkLHuPbPcYffu5gkOdvYEv7gNdhPcfSjWVuSPCY3TljJtl7hsFwxgG2wzPwapmRYyYt8QGo5UaOGQNvGwPjBgb2ZrwOY5z/BqLFeEaO8ce/bQz2hLXM4DGT/AB0mIFEjoE00JbEDQxsh/Fr6UlLk2Y4I8EjcedYmbRsm0TyjMNsyXi1GLYfPib541idHP/s5s0f37bZ2Pa3txnj19IADGgeEEuCAUoy49XAwCAPctwPhJZRMApGwSgYBZgAAEUSQ5am39FuAAAAAElFTkSuQmCC","orcid":"","institution":"Pusan National University, School of Dentistry","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Jeong-Kil","middleName":"","lastName":"Park","suffix":""}],"badges":[],"createdAt":"2023-01-25 07:59:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2512874/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2512874/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":37349420,"identity":"f26288cb-d5c1-4897-aedb-ef79ae3277a4","added_by":"auto","created_at":"2023-05-22 22:28:48","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":131904,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic flow chart of this study.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-2512874/v1/5be10b4228e1b2795ff4efcd.png"},{"id":37349643,"identity":"7a1b48d1-299a-4f09-823f-1702b540f88a","added_by":"auto","created_at":"2023-05-22 22:36:47","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":30502,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of average μTBS values for curing mode, dentin roughness, and dentin drying time. A, Curing mode. B, Dentin roughness. C, Dentin drying time. Error bars indicate the standard error of means, and asterisks (*) show statistically significant differences at P = 0.05.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-2512874/v1/70e01fde43ff24f263ed26d7.png"},{"id":37349418,"identity":"4d395278-3a94-442e-9bcc-5ca813dea6b8","added_by":"auto","created_at":"2023-05-22 22:28:47","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":44703,"visible":true,"origin":"","legend":"\u003cp\u003eμTBS values as a function of the curing mode, dentin roughness, and dentin drying time. Error bars indicate the standard error of means.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-2512874/v1/d97b2b13e7926a4bbdcdbb28.png"},{"id":37349644,"identity":"51af532f-0189-41c6-93b9-d479c917fb27","added_by":"auto","created_at":"2023-05-22 22:36:48","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":56671,"visible":true,"origin":"","legend":"\u003cp\u003eFailure modes for all groups.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-2512874/v1/545325a6026c0c80603eb856.png"},{"id":37349421,"identity":"7d872b46-4bd0-43f1-a89d-e8acf3e2b5c6","added_by":"auto","created_at":"2023-05-22 22:28:48","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1363162,"visible":true,"origin":"","legend":"\u003cp\u003eCLSM image of each group's bonding interface between dentin-resin cement.\u003cstrong\u003e \u003c/strong\u003eResin cement was stained with fluorescein, and universal adhesive was stained with rhodamine B, showing green and red fluorescent colors.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-2512874/v1/77eec867097cd6ce05e68aa5.png"},{"id":37349645,"identity":"3d997c3d-01bc-41b6-9a4c-cde5b15579a9","added_by":"auto","created_at":"2023-05-22 22:36:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1503289,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2512874/v1/f8766bbf-270b-4605-b209-13827dbf709e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of dentin surface conditions and curing mode of resin cement on the dentin bond strength for an indirect restoration","fulltext":[{"header":"Background","content":"\u003cp\u003eThe clinical success and longevity of bonded esthetic restorations depend on the adequate application of adhesive and resin cement to form an optimally bonded interface to the tooth structure [1,2].\u003csup\u003e\u0026nbsp;\u003c/sup\u003eThe application of resin adhesive cement is sensitive to the dentin surface conditions and the method of application of the dentin adhesive [3].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe bond strength of restoration to dentin increases if the adhesive layer is sufficiently polymerized before the application of resin cement [3]. However, when the adhesive layer is pre-cured, it may thicken locally or generally, depending on the geometry of the cavity [4,5]\u003csub\u003e,\u003c/sub\u003e\u003csup\u003e\u0026nbsp;\u003c/sup\u003ewhich interferes with the complete seating of the final restoration and causes a misfit between the restoration and the tooth [6].\u003c/p\u003e\n\u003cp\u003eThus, to prevent this phenomenon, a co-curing method was proposed, in which a resin cement was applied immediately without light irradiation after the adhesive was used [6-9]. Subsequently, the adhesive and resin cement were polymerized with light at once. This method minimizes the irregular thickness of dentin adhesives and reduces the possibility of the final restoration being a misfit [6,7].\u003csup\u003e\u0026nbsp;\u003c/sup\u003eIn addition, this method shortens the procedure time and leads to simple cementation sequences.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMeanwhile, when applying the dentin adhesive, the characteristics of the smear layer and the wetness of the dentin surface vary depending on the preparation method, in addition to the moisture management of the dentin surface [2,10]. When forming a cavity, the particle size of the used instrument affects the roughness of the dentin surface and, thus, the formation of the smear layer [11-14], which involves the interaction between the self-etch adhesive and hard tissue, including the smear layer on the dentin surface [2,12-14]. The wetness of the dentin surface also affects the ionization and penetration ability of acidic functional monomers of self-etch adhesives into dentin [15,16].\u003c/p\u003e\n\u003cp\u003eClinicians have been interested in practical methods for controlling the dentin surface conditions, such as wetness and roughness when applying adhesives and resin cement, and the effect of clinical technique that increases the convenience of the cementation procedure,\u0026nbsp;such as a co-curing technique on dentin adhesion.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis study aimed to investigate the effect of the drying time, the roughness of dentin, and curing mode\u0026mdash;whether the co-cured or separately light-cured universal adhesive and resin cement during the cementation of indirect restorations\u0026mdash;on its bond strength. The null hypothesis was that the curing mode of the adhesive layer and the roughness and drying time of the dentin surface do not affect the strength of the \u0026mu;TBS between the resin cement and dentin.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eTeeth selection\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFig. 1 shows the overall workflow of this study. The research protocol was approved by the Pusan National University Dental Hospital Institutional Review Board (IRB, PNUDH-2022-002). Forty extracted, caries-free human third molars were used within three months of extraction. The teeth were disinfected with 0.5% chloramine T and stored in distilled water at 4\u0026deg;C until needed. The teeth were sectioned horizontally using a water-cooled diamond saw to expose a flat, sound dentin surface (Accutom-50, Struers, R\u0026Oslash;dovre, Denmark).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExperimental design and specimen preparation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 1 lists the composition of the materials used in this study and the application procedure. To fabricate 40 resin disks, a silicon mold (4\u0026nbsp;mm thick and 9\u0026nbsp;mm in diameter) was filled with a hybrid composite resin (MI GraceFil A3 shade, GC Corp., Tokyo, Japan) layered in 2\u0026nbsp;mm thick increments and cured for 20\u0026nbsp;s with a light-curing unit (BluePhase G2, Ivoclar Vivadent Inc., Amherst, NY, USA) set to 1200 mW/cm\u003csup\u003e2\u003c/sup\u003e. All resin disks were then removed from the silicon mold, light-cured for 20 s on each side, and polished for 60 s with a 250-grit SiC abrasive paper (Carbimet Buehler-met, Buehler, Lake Bluff, IL, USA) using a polishing machine (Metaserv 250, Buehler, Lake Bluff, IL, USA ).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u0026nbsp;\u003c/strong\u003eMaterial compositions used in this study and application procedure\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"936\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.23076923076923%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eProduct name\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(Manufacturer/Lot number)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"41.02564102564103%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eChemical compositions\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.743589743589745%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eApplication mode\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.61290322580645%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eLight-curing mode\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.38709677419355%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCo-curing mode\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.23076923076923%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSingle Bond Universal\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e(3M ESPE, St. Paul, MN,\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;USA/9126149)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"41.02564102564103%\" valign=\"top\"\u003e\n \u003cp\u003e10-MDP, phosphoric acid ester monomer, HEMA, silane, dimethacrylate, Vitrebond copolymer, filler, ethanol, water, initiators, silane\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.512820512820515%\" valign=\"top\"\u003e\n \u003cp\u003e1. Apply the Adhesive to the dentin surface with rubbing motion for 20 s\u003c/p\u003e\n \u003cp\u003e2. Gently air thin for 5 s\u003c/p\u003e\n \u003cp\u003e3. Light cure for 10 s before applying resin cement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.23076923076923%\" valign=\"top\"\u003e\n \u003cp\u003e1. Apply the Adhesive to the dentin surface with rubbing motion for 20 s\u003c/p\u003e\n \u003cp\u003e2. Gently air thin for 5 s\u003c/p\u003e\n \u003cp\u003e3.No\u0026nbsp;light\u0026nbsp;cure\u0026nbsp;immediately after adhesive application\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.23076923076923%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eRelyX Ultimate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e(3M ESPE, St. Paul, MN,\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eUSA/9301016)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"41.02564102564103%\" valign=\"top\"\u003e\n \u003cp\u003eBase: silane-treated glass powder, 2-propenoic acid, 2-methyl-,1,1-[1-(hydroxymethyl)-1,2-ethanediyl] ester, reaction products with 2-hydroxy-1,3-propanediyl DMA and phosphorus oxide, TEGDMA, silane treated silica, oxide glass chemicals, sodium persulfate, tert-butyl peroxy-3,5,5-trimethylhexanoate, copper (II) acetate monohydrate\u003c/p\u003e\n \u003cp\u003eCatalyst: silane treated glass powder, substituted DMA, 1,12-dodecane DMA, silane treated silica, 1-benzyl-5-phenylbarbic-acid, calcium salt, sodium p-toluenesulfinate, 2-propenoic acid, 2-methyl-, [(3-metoxypropyl) imino]di-2,1-ethanediyl ester, calcium hydroxide, titanium dioxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.743589743589745%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1. Mix base and catalyst paste on the mixing pad\u003c/p\u003e\n \u003cp\u003e2. Apply cement to the resin disk, and place it on the prepared dentin surface\u003c/p\u003e\n \u003cp\u003e3. Remove excessive cement, then light-cure for 10 s on each surface.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"19.23076923076923%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMI GraceFil\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e(GC Corp.,\u0026nbsp;Tokyo, Japan\u003c/p\u003e\n \u003cp\u003e/2203111)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"80.76923076923077%\" colspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003eBis-GMA, UDMA, Bis-EMA, zirconia, silica\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eMDP: methacryloyloxydecyl dihydrogen phosphate; HEMA: 2-hydroxyethyl methacrylate; DMA: dimethacrylate; TEGDMA: tri-ethylene-glycol-dimethacrylate; Bis-GMA: bisphenol glycidyl methacrylate; UDMA: urethane dimethacrylate; Bis-EMA: ethoxylated bisphenol glycidyl methacrylate\u003c/p\u003e\n\u003cp\u003eForty specimens were cut perpendicular to the tooth axis and randomly divided into two parts to standardize the smear layer. For the coarse dentin group, 20 teeth surfaces were polished with a 250-grit SiC abrasive paper for 60 s, with the remaining 20 polished sequentially for 60 s with 250- and 600-grit SiC abrasive papers for the fine dentin group. The polishing machine was used to polish all specimens and rinse them with water for 30 s.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEach group was subdivided into two groups according to the drying time of the dentin surface: 5-s or 10-s drying groups. The dentin surface was blown for 5 or 10 seconds using a three-way air syringe with the air pressure adjusted to 1 bar using a pressure regulator. The air nozzle was held at 45\u0026deg; to the dentin surface at a distance of 1.5 cm.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEach group was divided into two subgroups\u0026mdash;co-curing and light-curing groups\u0026mdash; according to whether the dentin adhesive (Single Bond Universal, 3M ESPE, St. Paul, MN, USA) was polymerized before the resin cement (RelyX Ultimate, 3M ESPE, St. Paul, MN, USA) was applied. Table 1 presents a detailed description of the curing mode of the adhesive layer used in this study\u0026nbsp;[17]. Next, the resin discs were cemented with dual-cured resin cement under a seating force of 1 kg for 1 min, followed by light-curing for 20 s using the light-curing unit set to 1200 mW/cm\u003csup\u003e2\u003c/sup\u003e. After cementation, all specimens were stored in distilled water at 37\u0026nbsp;℃\u0026nbsp;for 24 h.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMicrotensile bond strength (\u0026mu;TBS) testing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll specimens were cut using the water-cooled saw to obtain 1 \u0026times; 1 \u0026times; 10 mm sticks. After randomly selecting 15 specimens from each group, \u0026mu;TBS of each group specimen was measured with a microtensile adhesive strength tester (Micro Tensile Tester, Bisco, Schaumburg, IL, USA) until fracture at a crosshead speed of 1.0 mm/min.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFailure mode analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAfter measuring \u0026mu;TBS, the failure mode was observed at a magnification of 40\u0026times; under a microscope (Extaro 300, Carl Zeiss, Oberkochen, Germany) and recorded. An adhesive failure was recorded when the failure occurred at the dentin-cement interface or between the resin disc and cement. A cohesive failure within cement layers was recorded. Mixed failure was recorded when the cohesion and adhesion failure patterns occurred at the dentin-cement interface. Moreover, the substrate failure was recorded when the failure occurred within the dentin or resin disc\u0026nbsp;[18].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConfocal laser scanning microscopy (CLSM) analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSixteen freshly extracted human third molars were selected for CLSM image acquisition. Selected teeth were transversally cut using the water-cooled saw to expose the dentin surfaces, which were prepared according to the protocols described above. Rhodamine B fluorescent dye (Rhodamine B, Daejung, Seoul, Republic of Korea ) was added to the adhesive system. Fluorescein isothiocyanate dye (FITC labeling kit, Abbkine, Wuhan, Hubei, China) was added to the resin cement at a concentration of 0.01 wt.%. All the specimens were vertically in the mesial-distal direction cut into a thickness of 1.0 mm. Confocal laser scanning microscopy (CLSM; LSM-700, Carl Zeiss, Oberkochen, Germany) was used to obtain images of the bonding interface in each group. The 200-fold magnified fluorescent images were obtained\u0026nbsp;[19].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Kolmogorov\u0026ndash;Smirnov and Levene tests were used to verify the normality and homogeneity of variance. Experimental data were analyzed using a 3-way analysis of variance (ANOVA) and Tukey\u0026apos;s post-hoc comparison test at a 95% confidence level. SPSS version 25 software (IBM SPSS Statistics, v25.0, SPSS Inc., Chicago, IL, USA) was used for statistical analysis.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eMicrotensile bond strength (\u0026micro;TBS) testing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 2 shows the \u0026mu;TBS mean values between dentin and resin cement in all the experimental groups according to the outlined factors of curing mode, dentin roughness, and dentin drying time. The light-curing-fine-5-s drying group showed the highest \u0026mu;TBS value (22.4\u0026nbsp;\u0026plusmn;\u0026nbsp;7.3 MPa), while the co-curing-fine-10-s drying group showed the lowest one (10.6\u0026nbsp;\u0026plusmn;\u0026nbsp;4.0 MPa).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u0026nbsp;\u003c/strong\u003eMean standard deviation of \u0026mu;TBS (MPa) between dentin and resin cement for all experimental groups\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCuring mode\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDentin roughness\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDentin drying time\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean \u0026plusmn; SD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\n \u003cp\u003eCo-curing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\n \u003cp\u003eCoarse\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e5-s drying\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e13.6\u0026nbsp;\u0026plusmn;3.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e10-s drying\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e13.3\u0026nbsp;\u0026plusmn;4.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\n \u003cp\u003eFine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e5-s drying\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e14.1\u0026nbsp;\u0026plusmn;2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e10-s drying\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e10.6\u0026nbsp;\u0026plusmn;4.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\n \u003cp\u003eLight-curing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\n \u003cp\u003eCoarse\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e5-s drying\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e20.6\u0026nbsp;\u0026plusmn;6.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e10-s drying\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e15.8\u0026nbsp;\u0026plusmn;5.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\n \u003cp\u003eFine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e5-s drying\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e22.4\u0026nbsp;\u0026plusmn;7.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.5%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"25.166666666666668%\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"26.333333333333332%\" valign=\"top\"\u003e\n \u003cp\u003e10-s drying\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e13.1\u0026nbsp;\u0026plusmn;3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 3 shows the 3-way ANOVA analysis results of the effect of curing mode, dentin roughness, and dentin drying time on \u0026mu;TBS between dentin and resin cement. The results confirmed that the curing mode (F = 24.6,\u0026nbsp;p\u0026nbsp;\u0026lt;\u0026nbsp;0.05) and dentin drying time (F = 18.9,\u0026nbsp;p\u0026nbsp;\u0026lt;\u0026nbsp;0.05) significantly affected bond strength, unlike dentin roughness (F = 0.5,\u0026nbsp;p\u0026nbsp;\u0026gt;\u0026nbsp;0.05). The interaction between the curing mode and dentin drying time (F = 6.4,\u0026nbsp;p\u0026nbsp;\u0026lt;\u0026nbsp;0.05) affected the bond strength. In contrast, interactions between the curing mode and dentin roughness (F = 0.1,\u0026nbsp;p\u0026nbsp;\u0026gt;\u0026nbsp;0.05) and dentin roughness and dentin drying time (F = 3.4,\u0026nbsp;p\u0026nbsp;\u0026gt;\u0026nbsp;0.05) did not affect the bond strength. All three factors (F\u0026nbsp;=\u0026nbsp;0.1, p \u0026gt; 0.05) did not show a significant interaction.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u0026nbsp;\u003c/strong\u003eResults of 3-way ANOVA analysis\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"599\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSource\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e\u003cstrong\u003edf\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e\u003cstrong\u003eMS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e\u003cstrong\u003eF\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003eCuring type\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e777.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e777.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e24.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e*0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003eDentin roughness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e16.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e16.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e0.467\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003eDentin drying time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e597.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e597.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e18.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e*0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003eCuring type\u0026nbsp;x\u0026nbsp;Dentin roughness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e0.751\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003eCuring type\u0026nbsp;x\u0026nbsp;Dentin drying time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e201.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e201.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e6.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e*0.013\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003eDentin roughness x\u0026nbsp;Dentin drying time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e108.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e108.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e3.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e0.067\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003eCuring type x Dentin roughness\u0026nbsp;\u003c/p\u003e\n \u003cp\u003ex\u0026nbsp;Dentin drying time\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e0.758\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"41.068447412353926%\"\u003e\n \u003cp\u003eError\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.687813021702839%\"\u003e\n \u003cp\u003e3540.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.68280467445743%\"\u003e\n \u003cp\u003e112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\n \u003cp\u003e31.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"12.186978297161936%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eANOVA, analysis of variance; df,\u0026nbsp;degree of freedom; MS,\u0026nbsp;mean squares; SS,\u0026nbsp;the sum of squares.\u003c/p\u003e\n\u003cp\u003e*\u0026nbsp;p\u0026lt;\u0026nbsp;0.05\u0026nbsp;indicates\u0026nbsp;a statistically significant difference.\u003c/p\u003e\n\u003cp\u003eFig. 2 compares average \u0026mu;TBS values for curing mode, dentin roughness, and dentin drying time. In terms of curing mode, the co-curing group (12.9\u0026nbsp;\u0026plusmn;3.9\u0026nbsp;MPa) showed significantly lower dentin-resin cement bond strength than the light-curing one (18.0\u0026nbsp;\u0026plusmn;\u0026nbsp;7.8 MPa) (p\u0026nbsp;\u0026lt;\u0026nbsp;0.05). In terms of roughness, the coarse surface group (15.8\u0026nbsp;\u0026plusmn;6.9\u0026nbsp;MPa) showed no significant difference in the dentin-resin cement bond strength compared to the fine surface one (15.1\u0026nbsp;\u0026plusmn;6.4 MPa) (p\u0026nbsp;\u0026gt;\u0026nbsp;0.05). In contrast, the 5-s drying group (17.7\u0026nbsp;\u0026plusmn;7.5 MPa) showed significantly higher dentin-resin cement bond strength than the 10-s drying group one (13.2\u0026nbsp;\u0026plusmn;4.7 MPa) (p\u0026nbsp;\u0026lt;\u0026nbsp;0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFig. 3 compares the co-curing and light-curing results as a function of the dentin roughness and drying time. The light-curing group showed greater bond strength than the co-curing one. In the coarse-5-s drying (co-curing, 13.6\u0026nbsp;\u0026plusmn;3.8 MPa; light-curing, 20.6\u0026nbsp;\u0026plusmn;\u0026nbsp;6.3 MPa) and fine-10-s drying (co-curing, 14.1\u0026nbsp;\u0026plusmn;2.6 MPa; light-curing, 22.4\u0026nbsp;\u0026plusmn;7.3 MPa) groups, the difference in the dentin-resin cement bond strength was more significant than in the other groups. The bond strength of the light-curing group was high compared to the co-curing one. The fine-10-s drying group exhibited a low bond strength regardless of the curing mode.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFailure mode analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFig. 4 shows the fracture mode of debonded specimens. Mixed fractures were common in most groups. The adhesive failure was frequently observed in the 10-s drying group; in the co-curing-fine-10-s drying group, adhesive failure was observed 47% of specimens. Cohesive and substrate failure patterns were observed in both light-curing and 5-s drying groups. In particular, in the light-curing-coarse-5-s drying group, cohesive failure was observed in 33% of specimens, and substrate failure was seen in 20%.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConfocal laser scanning microscopy (CLSM) analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFig. 5 shows CLSM images for each group. The boundary between the adhesive and cement was unclear in the co-curing group, but a clear adhesive layer was observed in the light-curing group. Compared to the 10-s drying group, the 5-s drying group had a higher density of adhesive penetrating the dentin tubule and showed a uniform penetration pattern. Images of high-density dentin adhesives deeply penetrated in the dentin were observed in the light-curing-coarse-5-s drying group.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study investigated the effect of three experimental factors of dentin surface roughness, dentin drying time, and curing mode of the adhesive layer on the dentin-resin cement bond strength during the cementation of indirect restorations. The \u0026mu;TBS was measured after the cementation of resin blocks on specimens with the dentin surface standardized to two roughness levels of the dentin surface, the air blotting time for moisture control of the dentin surface, and the curing mode of the dentin adhesive. Particularly,\u0026nbsp;in this study, to standardize the drying of the dentin surface, the dentin surface was blown for 5 or 10 seconds under room temperature using a three-way air syringe with the air pressure adjusted to 1 bar using a pressure regulator. The air nozzle was held at 45\u0026deg; to the dentin surface at a distance of 1.5 cm.\u003c/p\u003e\n\u003cp\u003eRegarding the effect of the curing mode on the \u0026mu;TBS, the co-curing group showed significantly lower bond strength than the light-curing one, regardless of the dentin\u0026apos;s roughness and drying time (p\u0026nbsp;\u0026lt;\u0026nbsp;0.05). The dentin adhesive used in this experiment was a Single Bond Universal adhesive with a relatively low pH of 2.7. An amine-free dual-cured resin cement (RelyX Ultimate;3M ESPE) was selected in this study to address the potential problem of resin cement-adhesive incompatibility due to the reaction between unpolymerized acidic monomer and the amine component of the dual-cured resin cement when using a self-etch adhesive with a low pH and dual-cured resin cement. The manufacturer reported that when a Single Bond Universal adhesive and RelyX Ultimate are used to cement indirect restorations, the adhesive layer can be applied without light irradiation\u0026nbsp;[17].\u003csup\u003e\u0026nbsp;\u003c/sup\u003eThis co-curing technique is possible as the self-curing component of the resin cement acts on the thin adhesive layer to achieve chemical polymerization. If dentin adhesive is pre-cured with a light irradiator before resin cement is applied, the thickness of the dentin adhesive varies depending on the cavity region\u0026nbsp;[5,6], especially prominent in areas where pooling of the adhesive may occur and lead to misfits during the seating of the final restoration due to the thickness of the polymerized dentin adhesive layer\u0026nbsp;[6,7]. In the CLSM images of this study, polymerization without a clear boundary between the dentin adhesive and resin cement was observed for the co-curing group, indicating that the dentin adhesive and resin cement were polymerized together. However, several studies have reported reduced bond strength when the dentin adhesive is co-cured with resin cement\u0026nbsp;[7,20-23]. In this study, the bond strength between dentin and resin cement was significantly lower in co-curing groups than in light-curing groups (p\u0026nbsp;\u0026lt;\u0026nbsp;0.05). These results suggest that when the light for polymerization is transmitted through the adhesive layer and resin cement in the co-curing groups, attenuation and dispersion of light energy occurs, limiting the light exposure for polymerization of the adhesive layer\u0026nbsp;[8,20]\u0026nbsp;and ultimately leading to unfavorable polymerization of the adhesive layer and unstable interface in the co-curing groups. In contrast, when the adhesive interface was photo-polymerized, the irradiated light directly reached and sufficiently polymerized the adhesive layer, stabilizing the adhesive interface and hybrid layer\u0026nbsp;[8,21,23].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe coarse surface group showed a slightly higher dentin-resin cement bond strength than the fine surface group, but no significant difference was observed between them (p\u0026nbsp;\u0026gt;\u0026nbsp;0.05). The dentin roughness factor did not significantly affect the bond strength (F = 0.5,\u0026nbsp;p\u0026nbsp;\u0026gt;\u0026nbsp;0.05). The study by Oliveira SS et al. showed that the characteristics of the thickness and roughness of the smear layer formed by 240-, 320, and 600-grits SiC papers were different. However, the bonding strength of the dentin adhesive applied to the smear layer formed with various roughnesses showed somewhat controversial results depending on the type of adhesive and the application method\u0026nbsp;[14]. The universal adhesive selected in this study had a slightly low pH of 2.7 and contained an acidic functional monomer (10-MDP)\u0026nbsp;[3].\u003csup\u003e\u0026nbsp;\u003c/sup\u003eThe adhesive\u0026apos;s acidity allows the penetration of the hydrophobic adhesive into the dentin while simultaneously allowing the acidic monomer to dissolve the dentin surface [24-26] microscopically.\u003csup\u003e\u0026nbsp;\u003c/sup\u003eIn addition, the chemical stability of 10-MDP contributed to the stability of the adhesive interface after polymerization\u0026nbsp;[2,3]. The result shows that the performance of the adhesive used in this study can minimize the effect of dentin roughness, which can be changed by various residues and abrasive particles accumulated on the dentin surface after surface polishing.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn contrast, the dentin drying time factor significantly affected the bond strength between dentin and resin cement\u0026nbsp;[10,15], exhibiting an exceptionally high bond strength, especially on 5-s drying surfaces (p\u0026nbsp;\u0026lt;\u0026nbsp;0.05). The CLSM images of the 5-s drying groups, compared to the 10-s drying group, had a higher density of adhesive penetrating the dentin tubule and showed a uniform penetration pattern. Notably, in this study, a high bond strength was observed for the light-curing-5-s drying groups regardless of the roughness of the dentin because the wet dentin environment positively affects the ionic activity of functional monomers and improves the self-etching function of the adhesive to dissolve the dentin matrix and allow the adhesive to penetrate sufficiently into the dentin\u0026nbsp;[3,15,16]. Subsequently, light irradiation of the adhesive layer causes sufficient polymerization of the adhesive interface and induces the stability of the hybrid layer. In the CLSM image of light-curing-5-s drying groups, regardless of the dentin roughness, the adhesive sufficiently penetrates the dentin compared to the other groups.\u003c/p\u003e\n\u003cp\u003eIn contrast, the difference in \u0026mu;TBS between the co-curing and light-curing groups was more negligible for the 10-s drying groups. In dry dentin, the ionization activity of the adhesive\u0026apos;s acidic monomer and penetration into the dentin matrix are insufficient for forming the dentin adhesion interface, thereby minimizing the effect of the subsequent light irradiation\u0026nbsp;[25]. Adhesive failure was frequently observed in 10-s drying groups compared to 5-s drying groups, particularly in the co-curing-fine-10-s drying group; adhesive failure was observed in 47% of specimens. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis study has a limitation in that it did not include the thermocycling accelerated aging process and comparison with other products, such as more hydrophilic adhesives. In this constrained study, pre-curing of the adhesive layer was more advantageous for the bond strength when using resin cement after applying the self-etching universal adhesive, as opposed to co-curing. Furthermore, dentin drying time plays a more decisive role than dentin roughness. The null hypothesis that the curing mode of the adhesive layer and the roughness and drying time of the dentin surface would not affect the bond strength of dentin-resin cement was partially rejected.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eBased on the findings of this in vitro study, when cementing indirect restorations using universal adhesive and resin cement, the following conclusions are drawn:\u003c/p\u003e\n\u003cp\u003e1. The curing mode of the adhesive layer affected the bond strength of the dentin-resin cement (p \u0026lt; 0.05). In particular, the light-curing mode exhibited a significantly higher bond strength than the co-curing one (p \u0026lt; 0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e2. The roughness of the dentin surface did not affect the bond strength of dentin-resin cement\u0026nbsp; (p \u0026gt; 0.05), Nevertheless, the dentin drying time significantly affected the bond strength of dentin-resin cement (p \u0026lt; 005). In particular, the 5-s drying group exhibited significantly higher bond strength.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eSiC: Silicon-carbide\u003c/p\u003e\n\u003cp\u003e\u0026mu;TBS: Microtensile bond strength\u003c/p\u003e\n\u003cp\u003eCLSM: Confocal laser scanning microscopy\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e10-MDP: methacryloyloxydecyl dihydrogen phosphate\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved for IRB review exemption by the Pusan National University Dental Hospital Institutional Review Board (IRB, PNUDH-2022-002),\u0026nbsp;which\u0026nbsp;waived the need for informed consent. This study was conducted in compliance with all research-related matters such as the research protocol, the Declaration of Helsinki, and standard operating procedures of the PNUDH IRB.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by a 2-year Research Grant from Pusan National University.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors made substantial contributions to the present study. In detail,\u0026nbsp;SAS and JKP conceived and designed the experiments; SAS performed the experiments; SAS,\u0026nbsp;JHK,\u0026nbsp;and\u0026nbsp;JKP analyzed the data; SAS,\u0026nbsp;JHK,\u0026nbsp;DGS.,\u0026nbsp;and\u0026nbsp;JKP contributed reagents/materials/analysis tools; SAS wrote the paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eO Connor CO, Gavriil D. Predictable bonding of adhesive indirect restorations: factors for success. Br Dent J. 2021 Sep;231:287-93.\u003c/li\u003e\n\u003cli\u003eAbad-Coronel C, Naranjo B, Valdiviezo P. Adhesive systems used in indirect restorations cementation: review of the literature. Dent J (Basel). 2019 Jul 1;7:71. doi:10.3390/dj7030071.\u003c/li\u003e\n\u003cli\u003eVan Meerbeek B, Vargas M, Inoue S, Yoshida Y, Peumans M, Lambrechts P, et al. Adhesives and cements to promote preservation dentistry. Oper Dent. 2001;26:119-44.\u003c/li\u003e\n\u003cli\u003eFrankenberger R, Kr\u0026auml;mer N, Petschelt AJ. Technique sensitivity of dentin bonding: effect of application mistakes on bond strength and marginal adaptation. Oper Dent. 2000;25:324-30.\u003c/li\u003e\n\u003cli\u003eStavridakis MM, Krejci I, Magne P. Immediate dentin sealing of onlay preparations: thickness of pre-cured dentin bonding agent and effect of surface cleaning. Oper Dent. 2005;30:747-57.\u003c/li\u003e\n\u003cli\u003eCoelho Santos MJ, Navarro MF, Tam L, McComb D. The effect of dentin adhesive and cure mode on film thickness and microtensile bond strength to dentin in indirect restorations. Oper Dent. 2005;30:50-7.\u003c/li\u003e\n\u003cli\u003eFrankenberger R, Sindel J, Kr\u0026auml;mer N, Petschelt A. Dentin bond strength and marginal adaptation: direct composite resins vs ceramic inlays. Oper Dent. 1999;24:147-55.\u003c/li\u003e\n\u003cli\u003eL\u0026uuml;hrs AK, Pongprueksa P, De Munck J, Geurtsen W, Van Meerbeek B. Curing mode affects bond strength of adhesively luted composite CAD/CAM restorations to dentin. Dent Mater. 2014;30:281-91. \u003c/li\u003e\n\u003cli\u003eTulunoglu O, U\u0026ccedil;taşh M, Ala\u0026ccedil;am A, Om\u0026uuml;rl\u0026uuml; H. Microleakage of light-cured resin and resin-modified glass-ionomer dentin bonding agents applied with co-cure vs pre-cure technique. Oper Dent. 2000;25:292-8.\u003c/li\u003e\n\u003cli\u003eKumagai RY, Hirata R, Pereira PNR, Reis AF. Moist vs over-dried etched dentin: FE-SEM/TEM and bond strength evaluation of resin-dentin interfaces produced by universal adhesives. J Esthet Restor Dent. 2020 Apr;32:325-32. doi:10.1111/jerd.12537.\u003c/li\u003e\n\u003cli\u003eAyad MF, Rosenstiel SF, Hassan MM. Surface roughness of dentin after tooth preparation with different rotary instrumentation. J Prosthet Dent. 1996 Feb;75:122-8. doi:10.1016/s0022-3913(96)90087-6.\u003c/li\u003e\n\u003cli\u003eTay FR, Pashley DH. Aggressiveness of contemporary self-etching systems: I: Depth of penetration beyond dentin smear layers. Dent Mater. 2001 Jul;17:296-308. doi:10.1016/s0109-5641(00)00087-7.\u003c/li\u003e\n\u003cli\u003eSaikaew P, Chowdhury AF, Fukuyama M, Kakuda S, Carvalho RM, Sano H. The effect of dentine surface preparation and reduced application time of adhesive on bonding strength. J Dent. 2016 Apr;47:63-70. doi: 10.1016/j.jdent.2016.02.001. \u003c/li\u003e\n\u003cli\u003eOliveira SS, Pugach MK, Hilton JF, Watanabe LG, Marshall SJ, Marshall GW Jr. The influence of the dentin smear layer on adhesion: a self-etching primer vs. a total-etch system. Dent Mater. 2003 Dec;19:758-67. doi:10.1016/s0109-5641(03)00023-x.\u003c/li\u003e\n\u003cli\u003eChoi AN, Lee JH, Son SA, Jung KH, Kwon YH, Park JK. Effect of dentin wetness on the bond strength of universal adhesives. Materials (Basel). 2017 Oct 25;10:1224. doi:10.3390/ma10111224. \u003c/li\u003e\n\u003cli\u003eSugimura R, Tsujimoto A, Hosoya Y, Fischer NG, Barkmeier WW, Takamizawa T, et al. Surface moisture influence on etch-and-rinse universal adhesive bonding. Am J Dent. 2019 Feb;32:33-8.\u003c/li\u003e\n\u003cli\u003eRely X. Ultimate Adheisve resin cement Brouchure;3m ESPE. \u003c/li\u003e\n\u003cli\u003eEl Zohairy AA, Gee AJ De, Mohsen MM, Feilzer AJ. Microtensile bond strength testing of luting cements to prefabricated CAD/CAM ceramic and composite blocks. Dent Mater. 2003 Nov;19:575-83. doi: 10.1016/s0109-5641(02)00107-0.\u003c/li\u003e\n\u003cli\u003eAguiar TR, Andre CB, Arrais CAG, Bedran-Russo AK, Giannini M. Micromorphology of resin\u0026ndash;dentin interfaces using self-adhesive and conventional resin cements: A confocal laser and scanning electron microscope analysis. Int J Adhes Adhes. 2012;38:69-74.\u003c/li\u003e\n\u003cli\u003eArrais CA, Rueggeberg FA, Waller JL, de Goes MF, Giannini M. Effect of curing mode on the polymerization characteristics of dual-cured resin cement systems. J Dent. 2008 Jun;36:418-26. doi:10.1016/j.jdent.2008.02.014. \u003c/li\u003e\n\u003cli\u003eArrais CA, Giannini M, Rueggeberg FA, Pashley DH. Microtensile bond strength of dual-polymerizing cementing systems to dentin using different polymerizing modes. J Prosthet Dent. 2007 Feb;97:99-106. doi:10.1016/j.prosdent.2006.12.007.\u003c/li\u003e\n\u003cli\u003eVukelja J, Klarić Sever E, Sever I, Jukić Krmek S, Tarle Z. Effect of conventional adhesive application or co-curing technique on dentin bond Strength. Materials (Basel). 2021 Dec 12;14:7664. doi:10.3390/ma14247664.\u003c/li\u003e\n\u003cli\u003eChapman JL, Burgess JO, Holst S, Sadan A, Blatz MB. Precuring of self-etching bonding agents and its effect on bond strength of resin composite to dentin and enamel. Quintessence Int. 2007 Sep;38:637-41.\u003c/li\u003e\n\u003cli\u003eSaikaew P, Sattabanasuk V, Harnirattisai C, Chowdhury AFMA, Carvalho R, Sano H. Role of the smear layer in adhesive dentistry and the clinical applications to improve bonding performance. Jpn Dent Sci Rev. 2022 Nov;58:59-66. doi:10.1016/j.jdsr.2021.12.001. \u003c/li\u003e\n\u003cli\u003eZecin-Deren A, Sokolowski J, Szczesio-Wlodarczyk A, Piwonski I, Lukomska-Szymanska M, Lapinska B. Multi-layer application of self-etch and universal adhesives and the effect on dentin bond strength. Molecules. 2019 Jan 18;24:345. doi:10.3390/molecules24020345.\u003c/li\u003e\n\u003cli\u003eMonticelli F, Osorio R, Mazzitelli C, Ferrari M, Toledano M. Limited decalcification/diffusion of self-adhesive cements into dentin. J Dent Res. 2008 Oct;87:974-9. doi:10.1177/154405910808701012.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"universal adhesive, curing mode, dentin roughness, dentin wetness, co-curing","lastPublishedDoi":"10.21203/rs.3.rs-2512874/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2512874/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e: During the cementation of indirect restorations, the conditions of the dentin surface and dentin adhesive's curing technique that affect the adhesion between dentin and an indirect restoration are essential issues for clinicians. This study investigates the effects of dentin's wetness, roughness, and curing modes of resin cement on bond strength when using universal adhesives for the cementation of indirect restorations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e: Forty human teeth were divided into eight groups according to three experimental factors: 1) dentin's roughness achieved by 250-or 600-grit Silicon-carbide (SiC) paper (coarse or fine), 2) dentin wetness with an air-drying time (5-s or 10-s), and 3) Single Bond Universal adhesive's curing mode by co-curing with RelyX Ultimate resin cement or light-curing separately after applying the adhesive(co-curing or light-curing). After resin discs were cemented with RelyX Ultimate, the microtensile bond strength (μTBS) was measured (n = 15 each). The failure mode and adhesive layers were observed using stereoscopic and confocal laser scanning microscopy (CLSM).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: The roughness of the dentin surface did not significantly affect the bond strength (p \u0026gt; 0.05), and the curing mode of dentin adhesive and the 5-s drying group of dentin had significant effects on bond strength (p \u0026lt; 0.05). Light-curing groups and 5-s drying groups showed significantly higher bond strength than co-curing groups (p \u0026lt; 0.05), and 10-s drying groups (p \u0026lt; 0.05), respectively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: When using Single Bond Universal adhesive and RelyX Ultimate resin cement, the light curing mode, in which the adhesive and resin cement is light-cured, showed higher bond strength than the co-curing mode. The bond strength between the resin cement and dentin was improved in the 5-s drying groups than in the 10-s drying groups.\u003c/p\u003e","manuscriptTitle":"Effect of dentin surface conditions and curing mode of resin cement on the dentin bond strength for an indirect restoration","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-05-22 22:28:43","doi":"10.21203/rs.3.rs-2512874/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"156c347b-9573-4668-86a6-90c801863310","owner":[],"postedDate":"May 22nd, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-05-22T22:28:43+00:00","versionOfRecord":[],"versionCreatedAt":"2023-05-22 22:28:43","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2512874","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2512874","identity":"rs-2512874","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}