Effect of Composite Viscosity, Cavity Type, and Placement Technique on Microleakage in Stamp Technique Restorations:...

The biomimetic restoration of occlusal morphology aims to replicate the natural form and function of dental tissues while preserving structural integrity. The stamp technique enables accurate reproduction of occlusal anatomy in posterior restorations; however, the extent to which different composite systems maintain marginal integrity and reduce microleakage when this technique is applied remains unclear. This in vitro study evaluated the microleakage of bulk-fill resin composites with different viscosities applied using the stamp technique. A total of 120 extracted human molars (n = 10 per group) were prepared with standardized Class I and Class II cavities and restored using SonicFill™, VisCalor, or Filtek™ Bulk-Fill composites, applied either in a single or two increments. After thermocycling, specimens were dye-penetrated, sectioned, and analyzed using ImageJ. Data were analyzed by two-way ANOVA and Tukey's HSD test (p < 0.05). In Class I cavities, occlusal microleakage differed significantly among materials (p = 0.001), with SonicFill™ showing the lowest values. In Class II cavities, gingival microleakage was significantly affected by both material and placement technique (p = 0.001). Incremental placement significantly reduced gingival microleakage for SonicFill™ and Filtek™ Bulk-Fill. Material viscosity and placement strategy influence marginal adaptation under stamp technique conditions. Low-viscosity bulk-fill composites demonstrated improved sealing, while incremental placement enhanced marginal integrity, particularly in Class II cavities.