The endodontic system of equine cheek teeth: A re-examination of pulp horns and root canals in view of age-related physiological differences

Abstract

The pulp horns and the root canals of the endodontic system of selected cheek teeth (left upper and left lower P3 = 207/307, M1 = 209/309) from 31 horses of large breeds (124 teeth) were examined in the dissection microscope (cross sections). From the right jaws, corresponding teeth were taken as histological controls to check for a vital pulp. The specimens were assigned to three age groups (<15 years; 15-23 years; >23 years; the oldest horse had an age of 27 years). Pulp horns had disappeared in many horses by an age of 23, but were present in a cheek tooth of the upper jaw even in a 25-year-old horse. Pulp horns disappeared earlier in M1 than in P3. The extension of the pulp horns towards the occlusal surface was markedly unsymmetrical in teeth with an extreme inclination of the occlusal surface. Root canals were regularly present in all (even in the very old) horses. The roots often contained more than one root canal. The number of root canals of the individual root varied especially in the mandibular cheek teeth. The apical foramen was closed in horses older than 23 years, but the pulp remained still vascularized, i.e. "vital" also in the older horses.