Enamel Margin Integrity Using One-bottle All-in-one Adhesives after Thermo-mechanical Stressing

Objective: To evaluate the continuity of the enamel margins of Class-I cavities restored by using contemporary one-bottle all-in-one adhesives, stressed by thermocycling and mechanical loading.

Methods: 96 extracted human molars were prepared for standardized Class-I-restorations (approximately 3 mm deep, 6 mm wide in mesio-distal direction, and 4 mm wide in buccal-oral direction). 12 adhesive systems: OptiBond FL (OPT), Clearfil SE Bond (CSE) and Adper Prompt L-Pop (PLP) as a control and nine one-bottle all-in-one adhesives AdheSe One (AHO), Adper Easy Bond (EB), Bond Force (BF), G-Bond (GB), iBond Self Etch (IB), One Coat 7.0 (OC), OptiBond All-in-one (OPA), Tri-S-Bond (TSB), Xeno V (XV), were used. All teeth were restored using Filtek Z 250, which was placed in three (one horizontal, two oblique) increments. Enamel margins were evaluated following 21 days of water storage, after thermocycling (2000 cycles: 5 to 55 °C), and after mechanical loading of 150,000 cycles of 50 N. After each step, replicas were produced and quantitative SEM margin analysis was performed (200x) to determine gap formation, irregularities and the continuity of enamel margins.

Results: Median values (% ”continuous margin”) for the different adhesive systems were OPT (98.6/96.2), CSE (95.4/90.9), BF (81.7/68.1), GB (81.1/65.0), OPA (83.0/68.1), OC (64.1/41.3), TSB (59.3/42.2), EB (57.1/42.6), IB (38.4/27.6), PLP (36.6/21.5), XV (45.0/30.0), AHO (17.7/5.4) after thermocycling and after mechanical loading, respectively. The statistical evaluation (Kruskal-Wallis-Test with Bonferroni adjustment, p<0.05) revealed the following ranking: OPT = CSE > BF = GB = OPA > OC = TSB = EB = IB = PLP = XV = AHO.

Conclusion: All one-bottle all-in-one adhesives exhibited statistically significant lower margin qualities in enamel compared to the etch & rinse system OPF and the two-step self-etching system CSE. The results obtained for GB, OPA and BF however, were better than for the other all-in-one adhesives.