Long-term histologic changes in the dental pulp after posterior segmental osteotomies

Objective. The purpose of this study was to examine pulp tissue for 18 mont hs after segmental osteotomy in nonhuman primates. Study design. In this long-term experimental study, subapical, posterior, m axillary, and mandibular osteotomies were done in 26 baboons (Papio ursinus ). Baboons were killed humanely immediately after operation and at 3, 6, 12 , and 18 months, when tissues were perfusion-fixed. Longitudinal step-seria l sections of dental pulps were examined. Results. There was a loss of the odontoblast layer as early as 3 months aft er surgery. Inflammatory cell infiltrate was most marked in the early posto perative stages, and the formation of osteodentin and secondary dentin was evident after 6 months. Foci of necrosis were present in the 3-month and 6- month groups bur were replaced by pulp fibrosis in the 12-month and 18-mont h groups. All these changes were more frequent in experimental than control teeth. Conclusions. The histologic changes seen should not affect the prognosis of teeth in subapical osteotomy segments if clinicians are careful not to dam age root apices and do regular, careful, clinical, and radiographic follow- up examinations. Because many pulps healed spontaneously in the study teeth , endodontic treatment should be delayed until it is clearly needed.