Cervical sclerotic dentin: Resin bonding

Abstract

Many reports have indicated that resin bond strengths to noncarious sclerotic cervical dentin are lower than bonds made to normal dentin. This is thought to be due to tubule occlusion by acid-resistant mineral salts, preventing resin tag formation following acid etching. The purpose of this review was to critically examine what is known about the structure of this type of dentin. Recent transmission electron microscopy revealed that in addition to occlusion of the tubules by mineral crystals, many parts of wedge-shaped cervical lesions contain a hypermineralized surface that resists the etching action of both self-etching primers and phosphoric acid. This layer prevents hybridization of the underlying sclerotic dentin. In addition, bacteria are often detected on top of the hypermineralized layer. Sometimes the bacteria were embedded in a partially mineralized matrix. Acidic conditioners and resins penetrate variable distances into these multilayered structures. Examination of both sides of the failed bonds revealed a wide variation in fracture patterns that involved all of these structures. Microtensile bond strengths to the occlusal, gingival, and deepest portions of these wedge-shaped lesions are significantly lower than similar areas artificially prepared in normal teeth. When resin bonds to sclerotic dentin are extended to include peripheral sound dentin, their bond strengths are probably high enough to permit retention of class V restorations by adhesion, without additional retention.