The first composite increment: Dependency on placement technique for interaction behavior with maturing dentin‑adhesive bond at pulpal floors in deep occlusal cavities – A comprehensive review.

Introduction: When the traditional incremental technique is used for direct placement of composite resin in a deep occlusal cavity, each increment (2 mm or thicker) is individually cured where it undergoes hardening and shrinkage. As increments are bonded to all cavity walls, a constrained shrinkage develops in tooth, composite, and/or interfaces. In the first composite increment, this constrained shrinkage generates tensile stresses which are distributed in a nonuniform pattern within that increment, resulting in premature stressing of the dentin bond of the hybrid layer at the pulpal floor before it reaches full maturation. This premature stressing leads to initiation of interfacial debonding and propagation to form a microgap. This behavior is associated with persistent postoperative sensitivity and tooth pain, over the time, which subsequently results in restoration failure. Aims: This paper provides a comprehensive review on the first composite increment and its dependency on placement technique for the interaction behavior with the maturing dentin‑adhesive bond at pulpal floors in deep occlusal cavities. Materials and Methods: The dental database was searched, and 59 articles were collected and included in this review, spanning the years from 1984 to 2023. Results and Discussion: Three biomimetic direct restorative techniques were reported in the literature for incrementally restoring large occlusal cavities. These techniques are the decoupling with time, the decoupling with fiber, and the decoupling with split‑increment. They all aim at minimizing the generated shrinkage stresses in the first composite increment for protecting the developing dentin bond of the hybrid layer until it reaches full maturation and thus preventing the initiation and propagation of interfacial defects at pulpal floors of deep occlusal cavities. Finally, the restoration is completed by placing and curing successive increments of 1.5 mm each to fill the cavity; their number depends on the cavity depth. These increments can each be cured immediately following placement. Conclusions: In deep occlusal cavities, the interaction behavior between the first composite increment and the maturing dentin‑adhesive bond at the pulpal floor depends on the technique used for the increment placement. This behavior is either favorable with the direct biomimetic techniques or unfavorable with the traditional incremental technique. With the direct biomimetic techniques, no premature shrinkage stressing of the dentin bond is induced at the pulpal floor. This prevents the initiation of interfacial debonding and propagation to form microgaps and results in the absence of postoperative sensitivity and persistent tooth pain. [ABSTRACT FROM AUTHOR]