The use of resin-based dental composites is multiplying through the years due to the increased demand for tooth-colored restorations. The choice of monomers strongly determines the viscosity, reactivity, mechanical property, water sorption and polymerization shrinkage of the composite material. It is desirable for all monomers to be converted into polymers (Degree of Conversion), but this does not occur clinically, resulting in a poor prognosis for restorations as well as an increase in systemic health risks. The release of monomers occurs due to erosion and degradation, as well as the release of leachable species from the restoration. The potential toxicity of free monomers to dental pulp cells is concerning. Free monomers are not only allergens but also have reported cytotoxic and genotoxic effects. Various methods and practices have thus been employed to counter the ill effects of free monomer release from dental composite restorations for better safety and healthy oral cavities.

Background This study investigates various surface treatment methods to assess shear bond strength between set Cention N (alkasite-based restorative material) and new alkasite based restorative material. Assessing different surface treatments provide insights in optimizing repair procedure that enables durability of the restoration, thus potentially benefitting clinical outcomes. Methods A total of 48 alkasite based restorative material blocks, measuring 4 mm in depth and 4 mm in diameter, were prepared. The samples were randomly divided into 8 groups (n = 6) according to the surface treatment done. Group I: Surface preparation by bur; Group II: Surface treatment by laser; Group III: Application of 2-step etch and rinse adhesive (Adper Single Bond 2 adhesive),Group IV: Application of single step self-etch adhesive (Scotchbond Universal adhesive); Group V: Bur preparation followed by application of 2-step etch and rinse adhesive; Group VI: Bur preparation followed by application of single step self-etch adhesive; Group VII: Laser preparation followed by application of 2-step etch and rinse adhesive; and Group VIII: Laser preparation followed by application of single step self-etch adhesive. Post-surface preparation, all the specimens were restored with newly mixed alkasite material. Repair bond strength measurements were assessed with universal testing machine. Shapiro-Wilk and Levene's tests were used to check normality and Homogeneity of variance. ANOVA with post-hoc Games-Howell test and two-way ANOVA with post-hoc Bonferroni test was performed to evaluate the influence of surface preparation on the repair bond strength. Results Using a 2-step etch and rinse adhesive resulted in a higher repair bond strength (26.05±2.12) compared to other surface treatments. In contrast, roughening of the surface with burs led to lowest repair bond strength (17.06±3.29) (P=0.02). Conclusion Application of 2-step etch and rinse adhesive to the existing alkasite based restorative material provides superior bonding with the newly added alkasite based restorative material.

Objective: To investigate the effect of 0.26mol/L Clodronate Disodium Tetrahydrate, 9% Etidronic acid (HEDP), and 17% Ethylenediaminetetraacetic acid (EDTA) on the dislodgement resistance of Biodentine. Material and Methods: 80 human single-rooted premolar teeth were selected. For bond strength analysis, samples were treated (n=15) according to the irrigation protocol employed: EDTA Group - 2.5% sodium hypochlorite (NaOCl) + 17% EDTA; HEDP Group - 9% Etidronic acid + 2.5% NaOCl; Clodronate Group- 0.26mol/L Clodronate + 2.5% NaOCl; and Control Group- 2.5% NaOCl + Distilled Water. Root canals were condensed with Biodentine, and 1.5 mm thick dentine discs were produced, and push-out bond strength was analysed. For FTIR analysis, dentine samples (n=5) were prepared (1cm × 1cm). Pre and post-irrigation scans were performed to compare compositional changes in the Amide III, Phosphate, and Carbonate infrared bands. One-way analysis of variance with post-hoc Tukey’s test was employed to analyze the results. Results: The highest bond strength value was obtained with 0.26mol/L Clodronate, followed by 9% HEDP and 17% EDTA (p<0.001). Amide III: Phosphate levels decreased with EDTA and HEDP, whereas the opposite was observed with Carbonate: Phosphate. No difference was observed with 0.26 mol/L Clodronate. Fractographic analysis revealed 20% adhesive failure, 48% mixed failure, and 32% adhesive failure, respectively. Conclusion: 0.26 mol/L Clodronate produced the most favourable outcome in terms of bond strength of Biodentine.

Background This study investigates various surface treatment methods to assess shear bond strength between set Cention N (alkasite-based restorative material) and fresh alkasite based restorative material. Assessing different surface treatments provide insights in optimizing repair procedure that enables durability of the restoration, thus potentially benefitting clinical outcomes. Methods A total of 48 alkasite based restorative material blocks, measuring 4 mm in depth and 8 mm in diameter, were prepared. The samples were randomly divided into 8 groups (n = 6) according to the surface treatment done. Group I: Surface preparation by bur; Group II: Surface treatment by laser; Group III: Application of 2-step etch and rinse adhesive (Adper Single Bond 2 adhesive),Group IV: Application of single step self-etch adhesive (Scotchbond Universal adhesive); Group V: Bur preparation followed by application of 2-step etch and rinse adhesive; Group VI: Bur preparation followed by application of single step self-etch adhesive; Group VII: Laser preparation followed by application of 2-step etch and rinse adhesive; and Group VIII: Laser preparation followed by application of single step self-etch adhesive. Post-surface preparation, all the specimens were restored with freshly mixed alkasite material. All samples were then subjected to repair bond strength measurements using a universal testing machine. ANOVA with post-hoc Games-Howell test and two-way ANOVA with post-hoc Bonferroni test was performed to evaluate the influence of surface preparation on the repair bond strength. Results Among the various surface treatments, use of a 2-step etch and rinse adhesive resulted in a higher repair bond strength compared to other surface treatments, whereas roughening of the surface using burs resulted in the lowest repair bond strength (P=0.02). Conclusion Application of 2-step etch and rinse adhesive to the existing alkasite based restorative material provides superior bonding with the freshly added alkasite based restorative material.