Polymerization shrinkage stress of composite resins and resin cements - What do we need to know?

Carlos José Soares,André Luis Faria-E-Silva,Monise De Paula Rodrigues,Antheunis Versluis,Andomar Bruno Fernandes Vilela,Daranee Tantbirojn,Carmem Silvia Pfeifer

doi:10.1590/1807-3107bor-2017.vol31.0062

Abstract

Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with post-operative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed.

Highlights

The bonding strategies associated with esthetic and conservative properties of resin materials have increased their popularity in restorative dentistry.[1]
When indirect restorations are cemented to a vital tooth, polymerization shrinkage may result in postoperative sensitivity or marginal debonding that contributes to marginal staining,[11] which is often erroneously used as a criterion for replacement of indirect and direct composite restorations (Figure 2C)
This review article will focus on polymerization shrinkage, polymerization stress, their consequences, strategies used by companies and clinicians to minimize the effects, starting with discussion of a selection of methodologies that are used for shrinkage measurements

Summary

Introduction

The bonding strategies associated with esthetic and conservative properties of resin materials have increased their popularity in restorative dentistry.[1]. A consequence of shrinkage stress can be debonding along the restoration/tooth interface or at the restoration margins, resulting in internal and marginal gaps, micro-cracking of either or both the restorative material and tooth structure, marginal stain cuspal movement (Figures 1 and 2).[6,7,8,9,10,11] When indirect restorations are cemented to a vital tooth, polymerization shrinkage may result in postoperative sensitivity or marginal debonding that contributes to marginal staining,[11] which is often erroneously used as a criterion for replacement of indirect and direct composite restorations (Figure 2C). Several experimental methods have been developed to measure polymerization shrinkage of composites and resin cements. This review article will focus on polymerization shrinkage, polymerization stress, their consequences, strategies used by companies and clinicians to minimize the effects, starting with discussion of a selection of methodologies that are used for shrinkage measurements

Methodology

Findings

H CH3 CH3 ON