Clinical performance and SEM marginal quality of extended posterior resin composite restorations after 12 years.

Objective: To investigate the clinical behavior of two different resin-based restorative systems in extended Class II cavities in a controlled prospective split-mouth study over 12 years and to assess marginal quality under a SEM using epoxy replicas.

Methods: Thirty patients received 68 resin composite restorations (Solobond M+Grandio: n=36; Syntac+Tetric Ceram: n=32) by one dentist in a private practice. 35% of cavities revealed no enamel at the bottom of the proximal box, 48% of cavities provided <0.5mm remaining proximal enamel. Restorations were examined according to modified USPHS criteria at baseline, and after six months, one, two, four, six, eight, 10, and 12 years. Expoxy replicas of 21 restoration pairs were analysed under a SEM at 200× magnification regarding marginal quality.

Results: At the 12-years recall, 59 of the original 68 restorations in 27 of 30 patients were available (drop out 13%). Two restorations failed due to cusp fracture (Tetric Ceram) and marginal fracture (Grandio). The overall success rate of all restorations was 97.1% (Kaplan-Meier survival algorithm) with no differences between the two materials (p=0.923). After 144 months of clinical service, restorations in molars performed worse than in premolars regarding the integrity of restoration and tooth (p<0.05) being detected as wear, chippings, and cracks. Beyond the 4-year recall, marginal staining significantly increased. SEM evaluation of replicas revealed that perfect margin (49% baseline vs. 10% after 12 years), overhang (13% at baseline vs. 3% after 12 years), negative step formation (34% at baseline vs. 75% after 12 years), and marginal fractures (0% at baseline vs. 6% after 12 years) significantly changed during the evaluation period (p<0.001).

Significance: Extended direct resin composite restorations performed satisfactorily over 12 years of clinical service. SEM analysis delivered qualitative data regarding marginal deterioration over time.