A study of freeze-dried (lyophilized) dentin used as an apical barrier in adult monkey teeth.

Thirty-two fully formed vital teeth of four adult cynomolgus monkeys were endodontically prepared to simulate conditions of an open apex. The apical 2 to 5 mm. of 24 teeth were filled with freeze-dried dentin. The eight remaining teeth received no implant material and served as controls. All the teeth were obturated with gutta-percha. The monkeys were sacrificed at 6, 13, 23, and 27 week periods, and the specimens were prepared for histologic examination. The early specimens showed acute inflammation apically; later specimens showed osseous healing. Some experimental teeth had partial cementum bridging against the implant material. Freeze-dried dentin was found to be a biocompatible material which can be used effectively as a substitute barrier against which gutta-percha can be condensed in mechanically prepared open-apexed monkey teeth.