Nanoleakage and marginal quality of direct composite veneering system for cervical fillings.

Aim of this study was to evaluate the marginal adaptation and nanoleakage in class V bonded restorations before and after thermo- mechanical loading using Componeer Class V (CCV) compared to con- ventional composites. The null-hypothesis tested was that marginal adap- tation and nanoleakage of CCV was not significantly different compared to conventional composites before and after thermo-mechanical loading. Standardized Class V cavities (width 2.0mm, length 3.0mm, depth 1.5mm) were created in 40 human premolars and molars at the cement- enamel junction. Cavity dimensions were standardized using a digital caliper. Teeth were divided in four groups (N=10): Group 1 One- coat- Bond-Self-etching bonding agent with Synergy-D6+CCV (Coltene); Group 2 One- coat-Bond-Self-etching bonding agent Synergy-D6- flow+CCV (Coltene), Group 3 Scotchbond Universal adhesive system with Filtek-Supreme-XTE (3M ESPE); (Group 4) Scotchbond Universal adhesive system with Filtek-Supreme-XTE-flow (3M ESPE). Restorations were placed according to manufacturers’ instructions. Marginal quality was analyzed under a SEM using epoxy resin replicas before and after thermo-mechanical loading (240,000 mechanical cycles x 50N with a frequency of 1HZ and 7800 thermo-cycles between 5° and 55C° with chewing simulator CS4-Mechatronik). Data were statistically analyzed by two-way ANOVA and Tukey’s post-hoc test (α=0.05).Specimens were then processed to investigate nanoleakage expression under SEM. The null hypothesis was partially accepted since no significant statistical differences were found in marginal adaptation with CCV compared to mar- gins obtained with conventional composite both before and after thermo- mechanical cycling (p>0.05). Conversely the nanoleakage analysis showed only significant differences between group 1 and group 4 (p<0.05). The marginal quality of class V cavities restored with CCV was similar to conventional composite restorations, both before and after thermo- mechanical cycling. Nanoleakage expression was dependent on the restor- ative material type. Further clinical research is essential to confirm that composite shells for direct veneering can be a valid restorative procedure.