Restoring Proximal Contact Integrity in Posterior Composite Restorations: A Matrix System and Incremental Placement Protocol for Eliminating Interproximal Voids

Abstract

Deficient proximal contacts in posterior composite restorations represent a persistent clinical challenge associated with food impaction, periodontal deterioration, and secondary carious lesions. This study evaluated the efficacy of a contoured sectional matrix system combined with a standardized incremental oblique layering protocol in achieving adequate contact point tightness and marginal ridge integrity. A total of 128 Class II cavities in premolars and molars were restored using either conventional circumferential matrix bands or contoured sectional matrices paired with the proposed placement protocol. Contact tightness was assessed using dental floss resistance scoring, digital bite-force analysis, and micro-CT marginal gap evaluation at baseline and 12-month recall. Results demonstrated statistically significant superiority of the sectional matrix-incremental protocol group in contact tightness (p < 0.001), marginal adaptation, and reduced interproximal void formation, establishing a reproducible clinical guideline for practitioners.