COMPARATIVE EVALUATION OF BULK-FILL AND INCREMENTAL TECHNIQUES ON MICROLEAKAGE AND MARGINAL ADAPTATION OF COMPOSITE RESTORATIONS: A SYSTEMATIC REVIEW

Abstract

Background: Polymerization shrinkage remains a challenge in resin composite restorations, potentially compromising marginal adaptation and leading to microleakage. Bulk-fill resin composites have been developed to allow placement in thicker increments to save clinical time, but their performance compared to conventional incremental layering techniques remains debated.

Objective: To systematically review and synthesize current evidence comparing bulk-fill and incremental layering techniques in terms of microleakage, marginal adaptation, internal gap formation, and depth of cure in Class I, II, and V dental restorations.

Methods: Following PRISMA 2020 guidelines, electronic searches of PubMed, Scopus, Web of Science, Embase, and Google Scholar were conducted from January 2006 to July 2025. Eligible studies included in vitro experiments, randomized controlled trials, and systematic reviews comparing bulk-fill and incremental techniques in human teeth. Data were extracted on study design, composite type, cavity class, testing methods, and main outcomes.

Results: Fourteen studies met the inclusion criteria, encompassing various cavity types and composite viscosities. Findings indicate that incremental layering generally provides lower microleakage scores and better internal adaptation than bulk-fill placement, especially in deep proximal restorations. However, no significant differences were reported in some studies when high-quality bulk-fill composites and optimized curing protocols were applied.

Conclusions: While bulk-fill composites can reduce procedural time, incremental layering remains a reliable method for minimizing shrinkage-related gaps and ensuring optimal marginal seal. Clinical decisions should consider cavity configuration, material properties, and curing technique to achieve durable restorations.