Pathway 13-9-1 Pulp Repair

Pulpal Repair

• Pulpal repair involves the formation of tertiary dentin, a specialized type of dentin that forms as a protective barrier against external stimuli.
• Pulp healing begins with macrophages removing debris, followed by the proliferation of fibroblasts, capillary buds, and collagen formation.
• The formation of tertiary dentin depends on the type of stimulus, the type of odontoblasts involved, and whether the stimulus leads to the loss of original odontoblasts.
• Tertiary dentin can be classified as reactionary dentin or reparative dentin.
• Reactionary dentin forms when the original odontoblasts are stimulated and the tubules remain continuous. It forms in response to stimuli such as excessive wear, cavity preparation, or restorative materials.
• Reparative dentin forms when the original odontoblasts are destroyed, and new odontoblast-like cells differentiate to form a new, less tubular, and more irregular dentin. The tubules are not continuous with the secondary dentin.
• The release of growth factors, such as TGF- b , IGF-1 and IGF-2 , BMPs, VEGF during secondary dentin formation plays a crucial role in stimulating the differentiation of mesenchymal stem cells into reparative dentin and new blood vessels.
• Calcium hydroxide, often used in apexification treatment, has a slight demineralizing effect on dentin, which releases TGF- b and accelerates reparative dentinogenesis.
• Potential future applications of molecular biology in restorative dentistry include:
  • Applying growth factors to dentin to stimulate peritubular dentin formation and occlusion of dentinal tubules.
  • Transfecting pulpal fibroblasts with BMP-7 to stimulate increased production of this growth factor.
  • Using specific amelogenin gene splice products (A 1 4 and A 2 4) to induce mineralization of root canals.
• The formation of tertiary dentin can be considered a reparative process:
  • It forms in response to injury and helps the pulp retreat behind a barrier of mineralized tissue.
  • It has also been observed in normal, unerupted teeth, suggesting that tertiary dentin formation might be a natural process.