[Theoretical and practical principles of dentinogenesis: hypotheses and confirmed clinically reality].

The problem of maintaining dental vitality and stimulating reparative processes is a priority in modern odontology. Restorative processes depend not only on the type and size of tissue damage, but also on the protection capacity and integrity of the structural/functional pulp-dentin boundary. Primary dentin that is initiated in the intrauterine period has unique structure and composition. Secondary dentin continues to form after the tooth is erupted, then after root formation is finished, and throughout life. Actually the primary and secondary dentins have similar tissue structures developed at different stages of dentinogenesis. Primary dentinogenesis is initiated by odontoblasts located in the periphery of dental pulp. Secondary dentin as a structure already exists once root formation is complete, but at that stage is has low levels of mineralization. Formation of tertiary dentin is always reactionary to different pathologies and is initiated by so called "transitional odontoblasts" (odontoblast-like cells) and partially fibroblasts. Odontotropic and anti-inflammatory medications strongly change structural characteristics of the dentin. Pulpal ability to produce dentin-like matrix (tertiary dentin) is an important component of the pulp-dentin reparative capacity. Only specific characteristics of the dentin can account for indications and contraindications for using restorative liners and explain the impact of adhesive systems on these. In this context, the interest is high to the dentin and its response and change in reaction to different stimuli. Dental caries and other pathological processes (abrasion, erosion, attrition) seriously affect dentin vital activity causing it to change to the "emergency" mode. This process is viewed not as resulting from pulp medication but as reactionary, aimed for self-preservation. In such cases the major focus is not on drug composition but on pulpal response. The pulp may be said to "form tertiary dentin for self-protection". In conclusion, the tertiary dentin that forms as a result of pathological processes (express-dentin, reparatory dentin) could be identified as a perfect barrier for the pulp necessary for keeping it vital. And investigation of mechanisms causing primary stimulation of odontoblasts and triggering the reparative processes remains a pressing problem in modern odontology.