Odontoclast

An odontoclast is a multinucleated resorptive cell associated with dental tissues. It is analogous to an osteoclast in bone and is derived from the monocyte/macrophage lineage. Odontoclast differentiation and activation are driven by local signaling factors, including RANKL and M-CSF, within the dental resorption environment.

The primary function of odontoclasts is the resorption of dental hard tissues, especially dentin and cementum, with enamel resorption occurring only in limited or pathological circumstances. Odontoclasts play essential roles in physiological processes such as the eruption of permanent teeth and the shedding of deciduous teeth, where root resorption facilitates tooth replacement. They can also be involved in orthodontic tooth movement, pathologic root resorption, and certain inflammatory or traumatic dental conditions.

Histologically, odontoclasts are found in resorption lacunae (Howship lacunae) at the surface where resorption occurs. They resemble osteoclasts, containing multiple nuclei and displaying tartrate-resistant acid phosphatase (TRAP) activity. Their activity leads to the removal of dental hard tissue and, in some contexts, can contribute to resorption of adjacent cementum and dentin.

Clinical relevance includes understanding mechanisms of root resorption, managing orthodontic forces to minimize undesired resorption, and differentiating odontoclast-mediated dental resorption from bone resorption. Related terms include cementoclast, which specifically resorbs cementum, and osteoclast, which resorbs bone.