MORPHOLOGICAL CHARACTERIZATION OF THE INTERFACE BETWEEN RESIN AND SCLEROTIC DENTIN

Since dentine exposed to the oral environment undergoes important comp ositional and morphological transformations, bonding to it differs sig nificantly from bonding to unaffected normal dentine. In this investig ation, the interface between resin and sclerotic dentine, the dentine type clinically exhibited by cervical abrasive or erosive lesions, was morphologically characterized by scanning electron microscopy after a n argon-ion-beam etching procedure. The microstructure of the resin-sc lerotic dentine interface was compared with that produced to normal un affected dentine in an attempt to find reasons for the reported less r eliable bonding of adhesive resins to sclerotic dentine. A resin-denti ne interdiffusion zone or hybrid layer with only a limited width was f ormed at the hypermineralized intertubular dentine. No or only short r esin tags were developed in most dentinal tubules, since their orifice s were obliterated due to increased peritubular dentine apposition, in tratubular deposition of irregular minerals and formation of so-called sclerotic casts. Consequently, it is reasonable to predict that denti ne adhesives with an adhesion strategy, which mainly involves micromec hanical interlocking by the formations of a resin-dentine interdiffusi on zone combined with resin-tag development into the dentinal tubules, will be less effective when applied to sclerotic dentine than to unaf fected normal dentine. An adapted adhesive treatment may be necessary to make sclerotic dentine more receptive to bonding. Further research should be directed to develop adhesive systems that bond equally well to various kinds of dentine.