Marginal Adaptation of Adhesive Systems Following Different Cavity Disinfectants

Objectives: The purpose of this in vitro study was to evaluate the influence of different cavity disinfectants on the marginal and internal adaptation of four adhesive systems in enamel and dentin.

Methods: One hundred standardized Class-II-cavities with margins in enamel and dentin were prepared and randomly assigned to five cavity disinfectants: 3% hydrogen peroxide (H2O2), 0.1% chlorhexidine digluconate (CHX), 2% CHX, 2% CHX/alcohol and sodium chloride (NaCl). Five cavities of each group were treated with one of the following bonding systems: Optibond FL®, Optibond Solo®, Solobond Plus® and Futurabond®. Afterwards all cavities were restored with the respective composite materials. Marginal and internal adaptations were quantitatively evaluated before, after thermal (2,500 times between 5˚C and 55˚C) and after mechanical (25,000 times 100 N) load cycling using standard SEM (magnification 320x) procedures. The fraction of perfect marginal adaptation in relation to the total marginal distance was calculated (% (range %)) and after sectioning the morphology of the internal interfaces was evaluated semi-quantitatively.

Results: All cavity disinfectants showed statistically significantly reduced marginal adaptation compared to the NaCl treatment (enamel: 97.2% (5.0%), dentin: 93.8% (3.9%)) irrespectively of the adhesive system used (p<0.05, Kruskal-Wallis- and Mann-Whitney U-Test). Disinfection with 2% CHX showed a significantly reduced marginal adaptation with Futurabond® (88.8% (2.0%)) in enamel compared to H202 (93.3% (4.7%), p=0.016), 0.1% CHX (93.2% (3.9%), p=0.008) and 2% CHX/alcohol (92.6% (2.2%), p=0.008). Cavity disinfection using H2O2 significantly reduced marginal adaptation in dentin with Optibond FL® (87.3% (4.5%)) compared to 0.1% CHX (90.6% (4.0%), p=0.008), 2% CHX (91.1% (2.1%), p=0.016) and 2% CHX/alcohol (91.4% (3.2%), p=0.016). The internal adaptation revealed increased dye penetration for Optibond Solo® combined with 2% CHX/alcohol compared to the other treatments.

Conclusions: The results of the present study demonstrated that cavity disinfection significantly affects marginal adaptation of adhesive systems in enamel and dentin.