Procedure time and filling quality for bulk-fill base and conventional incremental composite techniques-A randomised controlled in vitro trial.

Objectives: The aims of this randomised controlled laboratory trial were to determine the procedure time and immediate quality (surface porosity and marginal gaps) of fillings placed using the bulk-fill base technique and the conventional incremental technique in simulated clinical settings.

Methods: Forty-two dentists and dental students were randomly allocated to use either the bulk-fill base technique or the conventional incremental technique to fill an identical class II disto-occlusal cavity in a maxillary left first molar typodont tooth. We recorded the time the participants used to fill the cavity and evaluated the surface porosity and marginal gaps on the approximal surfaces of the fillings using a stereomicroscope and specific probes according to the FDI criteria for restoration evaluation. Data were analysed using the Mann-Whitney U, Kruskal-Wallis, and chi-square tests.

Results: The median time ± interquartile range was 186 ± 80 s for the bulk-fill base technique and 463 ± 156 s for the conventional incremental technique (p < 0.001). The quality of the fillings was better for the bulk-fill base technique than for the conventional incremental technique (X = 9.5, p = 0.002). Neither operator experience nor the usual technique of choice were associated with the procedure time or the quality of the fillings.

Conclusions: Compared to the conventional incremental technique, the use of the bulk-fill base technique shortened the time to fill a cavity by 59.8 % or 4 min and 36 s, and it improved the immediate surface and marginal quality of the fillings, regardless of the operator's experience or technique preference.

Clinical Significance: The use of the bulk-fill base technique instead of the conventional incremental technique leads to significant time-savings when placing large class II composite fillings. Additionally, the use of the bulk-fill base technique instead of the conventional incremental technique improves the immediate quality of large class II composite fillings.