Authors: Holland GR.
Title: The odontoblast process: form and function.
Journal: J Dent Res
Date: Apr 1985
Citation: 64 Spec No:499-514
Category: Endodontic Biology, Histology and Physiology
Evidence-based Ranking: 5
Purpose/Objectives: To review the odontoblast structure, extent, lateral branching, function in dentinogenesis, changes post-maturation, and in sensory reception.

Structure: The structure only became clear once preparatory methods available allowed for ultra-thin preservation and sectioning. The process is the direct extension of the cell body, and their plasma membranes are continuous. Cytoplasmic content changes with microfilaments and microtubules predominating. Organelles like rER, mitochondria, ribosomes become more rare the further the process extends from the body.

Extent: The length of extension is “controversial”. Much of the debate is reviewed. Questions of whether or not the process extends from the DEJ - the pulp are considered. Studies show the process does not extend more than a third of the length of the tubule. SEM evidence as well as radioactive tracers aids detection.

Lateral Branches: The branching of process is discussed. Each tubule gives off side branches seen at right angles to the main process. The system may provide pathways for the movement of nutrients and matrix constituents.

Dentinogenesis: Role of the process in dentinogenesis is the transport of secretory vesicles and their release into the extracellular space. Collagen precursors are secreted in vesicles from the odontoblastic process. Processes play a role in calcification of dentin by initiating the process, transporting calcium, modification of matrix composition and in changes that produce peritubular and secondary dentin.

Post-maturation changes: After primary dentin, secondary dentin, tubular dentin and reparative dentin form. Debate over how the processes contribute to these formations are mentioned.

Sensory reception: The possible role of the odontoblastic process in the sensory mechanism is reviewed including mention of the debate between the hydrodynamic theory and the theory of the odontoblastic process being directly stimulated and acting like a nerve receptor.