THE DENTIN SUBSTRATE - STRUCTURE AND PROPERTIES RELATED TO BONDING

Objectives: Dentin is a vital, hydrated composite material with struct ural components and properties that vary with location. These variatio ns are reviewed along with alterations by physiological and pathologic al changes that allow classification into various forms of dentin. Str uctural characteristics and mechanical properties are reviewed and the limitations of our understanding of structure-property relationships for normal and modified forms of dentin are discussed with respect to their impact on dentin bonding. Recent progress in methods available t o study dentin and its demineralization are emphasized with their prom ise to increase our understanding of dentin properties and structure. Data sources: Recent microstructural studies, focusing on scanning ele ctron microscopy, atomic force microscopy and X-ray tomographic micros copy are included. A review of fundamental studies with emphasis on mi crostructurally sensitive methods, and prior reviews of basic mechanic al properties are included with discussion of their correlation to com position and structure. Study selection ann conclusions: Emphasis in t his work was placed on the major structural components of the tissue, including the collagen based organic matrix and its mineral reinforcem ent, the distribution of these components and their microstructural or ganization as related to mechanical properties and response to deminer alization. Little information is included on biochemical and developme ntal studies or on non-collagenous proteins and other organic componen ts for which limited understanding is available with respect to their role in structure-property relations and influence on bonding. In spit e of the fact that the complexity of dentin precluded a comprehensive review, it is clear that local structural variations influence propert ies and impact nearly all preventive and restorative dental treatments . Much more work is needed in order to understand differences between vital and non-vital dentin, and dentin from extracted teeth. Although our knowledge is rudimentary in certain areas, increasingly sophistica ted methods of studying dentin should provide the necessary informatio n to model structure-property relations, optimize dentin bonding, and improve many aspects of preventive and restorative dentistry. (C) 1997 Elsevier Science Ltd. All rights reserved.