Clinical Performance of Bulk-Fill Versus Incremental Layering Techniques in Class II Restorations: A Systematic...

The promise of faster, simpler restorations has driven the rise of bulk-fill composites, but do speed and simplicity come at the cost of longevity and marginal integrity?

To compare and rank the clinical performance of bulk-fill and conventional incremental layering restoration techniques in Class II posterior restorations through a network meta-analysis (NMA).

Following PRISMA 2020 guidelines, a comprehensive electronic search was conducted across five databases. Twelve randomized clinical trials met the eligibility criteria. Risk of bias was assessed using RoB2, and confidence in evidence was evaluated through CINeMA. Network meta-analyses at 6, 12, and 24 months estimated relative risks for marginal adaptation, fractures, and retention using random-effects models.

Across all follow-ups, no statistically significant differences were observed between bulk-fill and incremental techniques. Risk ratios clustered around unity, and P-scores indicated minimal ranking variability, confirming comparable outcomes among bulk-fill subtypes regardless of viscosity or curing mode. Most evidence was rated as low risk of bias with acceptable indirectness. CINeMA indicated predominantly low concerns for indirectness and risk of bias, supporting the robustness and transitivity of the network. The ormocer-based and overlay bulk-fill composites showed the highest, though not statistically superior, ranking probabilities at 12 and 24 months.

Across 6-, 12-, and 24-month follow-ups, no statistically significant differences were detected between bulk-fill techniques and incremental placement for the primary outcomes (marginal adaptation, fractures, and retention). Treatment rankings (P-scores) showed minimal separation overall; ormocer-based and overlay bulk-fill configurations tended to occupy higher ranks at 12-24 months, but without statistically confirmed superiority.

This systematic review and network meta-analysis provides robust, evidence-based guidance to support clinical decision-making in the restoration of posterior Class II cavities. The findings indicate that bulk-fill resin composites regardless of viscosity or formulation demonstrate clinical performance comparable to conventional incremental layering techniques, while markedly simplifying placement procedures and enhancing operative efficiency.

This review was prospectively registered in the International Prospective Register of Systematic Reviews (PROSPERO; registration number CRD420251170292).