Modified Split-Increment Technique with Delayed Gap Closure for Incremental Placement of Posterior Composite Restorations: A Biomechanically Oriented Approach to Shrinkage Stress Reduction-A Conceptual Framework

Hassan KA and Khier SE

Published on: 2025-12-06

Abstract

Objectives: To present a modified variation of the split-increment technique for incremental placement of conventional composite resin restorations in posterior teeth, incorporating segmentation of the first increment with delayed gap closure, followed by simplified layering for subsequent increments. The biomechanical rationale, procedural sequence, and clinical implications are outlined.

Methods: The technique begins with placement of a 2.0 mm thick composite increment over the pulpal floor in occlusal cavity. This increment is diagonally split to create a 1.5 mm wide gap, which is then cured for the first time with the gap open. The gap is left open for a 5-minute delay period, then it is filled with the same composite and cured for the second time. The remaining restoration is completed using unsplit horizontal increments (2.0 mm thick, each), which is each light-cured immediately upon placement. Finishing and polishing follow.

Results and Discussion: Segmenting of the first increment reduces polymerization shrinkage stress by providing unbonded surfaces for relief and allowing post-cure shrinkage to occur away from critical bonded interfaces. Delaying gap closure for 5 minutes after the first cure allows flow and visco-elastic stress relaxation during the early “post-cure” period, potentially reducing residual stress at the adhesive interface. The resulting “stress-relieved foundational increment” supports simplified placement of the remaining increments without further segmentation. The technique draws on principles reported in modified semi-split bulk filling methods that benefit from delayed gap closure. Clinical implications include enhanced bond integrity, decreased debonding risk, and improved longevity of restorations. This technique combines enhanced biomechanical behavior with clinical practicality.

Conclusion: The modified split-increment technique may represent a clinically feasible method to modulate stress development during composite polymerization. This technique may improve marginal integrity, reduce debonding risk, and enhance restoration longevity while minimizing technique complexity in upper increments. Further research is required to validate its biomechanical performance and long-term clinical outcomes.