Five-year survival of class II restorations with and without base bulk-fill composite: a retrospective cohort study.

Objective: This study aimed to determine the survival of class II composite restorations in premolars and molars with and without base bulk-fill composite in general dental practice.

Materials and methods: We collected data from the electronic patient files of the Public Dental Services in the City of Oulu, Finland. The timespan of data collection was from August 15th, 2002, to August 9th, 2018. The data consisted of class II composite restorations both with and without base bulk-fill composite. We compared the survival of these restorations using Kaplan-Meier survival curves, the log-rank test, survival rates, and the Wilcoxon signed ranks test.

Results: We observed 297 restorations in 96 patients. The five-year survival rates for restorations with and without base bulk-fill composite were comparable in premolars (77.5% and 77.4%, respectively) but different in molars (69.9% and 57.8%, respectively, p = 0.069). In molars, the restorations with base bulk-fill composite exhibited a higher survival rate in 14 patients, whereas in 11 patients the restorations without base bulk-fill composites exhibited a higher survival rate. In 24 patients the survival rates were similar for restorations with and without the base bulk-fill composite (p = 0.246).

Conclusions: The restorations with and without base bulk-fill composite had similar longevity.

Clinical relevance: Base bulk-fill composites are safe to use in general practice due to their similar survival rates compared to conventional composites.