odontoblasts

Odontoblasts are specialized cells of the dental pulp responsible for dentin formation. They are derived from neural crest cells of the dental papilla and line the border between the pulp and predentin. In mature teeth they are arranged as a single layer of tall, columnar cells with their nucleus oriented toward the pulp and with slender processes that extend through dentinal tubules into the mineralized dentin.

Structure and secretion: The cell body contains organelles for protein synthesis, including prominent rough endoplasmic reticulum and Golgi apparatus. Odontoblasts synthesize collagen type I and non-collagenous proteins, notably dentin sialophosphoprotein (DSPP), which is cleaved into dentin sialoprotein and dentin phosphoprotein. They secrete predentin, which gradually mineralizes to form dentin. The odontoblastic process within each tubule becomes enveloped by mineralized dentin and may participate in dentin mineralization at its tip.

Dentinogenesis and dentin types: Primary dentin forms during tooth development; secondary dentin is laid down slowly after eruption; tertiary dentin (reactive or reparative) forms in response to injury, often involving odontoblast-like cells derived from pulp when original odontoblasts die.

Regulation and significance: Odontoblasts coordinate with dental pulp cells and signaling pathways such as TGF-β and BMPs; they contribute to the pulp-dentin complex's sensory and reparative functions. They help maintain dentin integrity and can respond to stimuli by releasing signaling molecules and remodeling matrix.