8 - Morphologic and structural analysis of material-tissue interfaces relevant to dental reconstruction

Abstract

Adhesive bonding to the tooth may be more difficult than anticipated, due to the different morphology and structure of dentin and enamel at various locations within the tooth cavity preparation. Bonding to enamel is the “gold standard” when the adhesive is bonded to the ends of enamel rods. Adhesive bonding to the ends of enamel rods yields greater adhesive bond strengths than bonding to the sides of the enamel rods. Successful adhesive bonding to enamel located at the cervical or gingival cavosurface margin of class II resin composite preparations is more difficult than bonding to enamel in the occlusal third of the tooth preparation. Variables that can impact the bond to the dentin include the orientation of the dentin tubules. For example, bonding to the sides of the dentin tubules, which are arranged in a parallel direction, will yield greater adhesive bond strengths when compared with bonding to dentin, which is oriented in a direction perpendicular to the exposed dentin tubules. The perpendicular orientation is found at the gingival wall of class II resin composite preparations. This chapter will address the morphological and structural differences of dentin and enamel within the cavity preparation and the effect that these differences have when restoring a tooth. These morphologic and structural differences may impact the quality of the adhesive bond formed at the composite/tooth interface, and indeed, results from clinical studies have indicated that the gingival margin is particularly vulnerable to failure. Understanding the morphologic and structural differences in the tooth and the impact of these differences on the adhesive bond offers the dentist insight into variables that must be considered when restoring teeth with adhesive and resin composite materials.