Effects of aging on the endodontic system, reserve crown, and roots of equine mandibular cheek teeth

Abstract

Abstract Objective To document age-related changes in the morphology of the endodontic system, reserve crown, and roots of equine mandibular cheek teeth. Design Equine mandibular cheek teeth from horses of various ages were compared, using radiography, x-ray computed tomography, and histologic examinations. Sample Population 48 right hemi-mandibles from horses 2 to 9 years old. Procedure Hemi-mandibles were radiographed, imaged by computed tomographic reconstruction, and reformatted. Histologic examination was used to identify and correlate tissue types. Results Permanent mandibular cheek teeth of the horse, at the time of eruption, consisted of an exposed crown and a reserve crown with a widely dilated apex. The endodontic system consisted of 5 or 6 pulp horns that connected to an expansive pulp in the reserve crown, which was confluent with the primordial pulp bulb surrounding the tooth’s apex. At the time of eruption, mandibular cheek teeth did not have a distinct pulp chamber, roots, or evidence of root formation. However, within 2 years after eruption, mesial and distal roots and a pulp chamber were present. A distinct pulp chamber, communicating with the pulp horns and both root pulp canals, was identifiable for 4 to 5 years from the time of root formation. The endodontic system of cheek teeth, 6 to 8 years after eruption, consisted of 2 unattached compartments, made up of a root canal, pulp chamber, and 2 or 3 pulp horns. Clinical Relevance The age-related morphologic changes in equine mandibular cheek teeth have important implications for application of endodontic therapy in horses. (Am J Vet Res 1996;57:31-38)