ODONTOBLASTIC AND PULPAL CELL BEHAVIOR UN DER CARIOUS LESIONS

The odontoblast responds to caries by the formation of sclerotic as we ll as reparative dentin. Sclerotic dentin is deposited during the earl y stages of the dentinal injury. It is characterized by the amplificat ion of the collagen synthesis and the increase in alcaline phosphatase activity in the odontoblastic cell layer. Reparative dentin will be d eposited under the sclerotic zone after the destruction of odontoblast s. At this stage, specific components from dammaged dentinal tissues a nd/or odontoblastic necrotic debris will trigger pulpal cells to elabo rate a cartilagelike matrix layer (fibrodentin). The latter may induce pulpal odontoblast-like cells to give rise to the tubular reparative dentin. Thus, pulpal cell response seems to be similar to bone-cell re sponse to injury. Molecular signals responsible for this tissular heal ing remain largely unknown, but dentin is a potential source of matric ial or soluble organic molecules that may be released after deminerali zation. Some of these factors have been identified in the sound tissue (glycoproteins, proteoglycanes, growth factors,...), but their role i n the stimulation of the elaboration of the cicatricial tissue remains to be elucidated.