Abstract
The purpose of this study was to evaluate short -term response to the use of Hydroxyapatite (HAP) in periodontal osseous defects and response in the process of regeneration of bone and soft connective tissue, intervening between newly formed bone and tooth during experimental tooth movement.
Bone defects were created surgically at the levels of the cervical and apical one third of the alveolus in four beagle dogs, clinically free of periodontal diseases, on the distal and mesial sides of P2 and P3 premolars bilaterally, from which the mesial roots had been already extracted before the surgical procedure. HAP were implanted into the artificial bone defects, adjacent to the teeth, and no material was implanted as a control.
By the 30th day, the defects were partially filled with woven bone and osteoid around the HAP particles. At that time one half of both the HAP -and the control-teeth were moved with orthodontic force in one duration for the next 30 days (experimental group).
After the tooth movement, we analyzed how the bone and periodontal ligament had been newly formed and also regenerated during the time of repair, especially during the tooth movement period.
The result of this study was as follows;
The amount of movement of the HAP implanted tooth in its apical site of the physiological group without orthodontic force was less than that of the control physiological group. However, the HAP experimental group in the same situation experienced more movement than the control experimental group.
The force tended to tilt the tooth, a region of compression developed between the root and the cervical one third of the alveolus and a region of tension formed on the other side. Results showed that a resorption of the old alveolar bone was observed in the compression zone and even a resorption of the new bone depositions, by which the alveolus covered during the repair period, were seen. In the apical region the sides with tension and compression were reversed and the resorption of bone took place most markedly on the newly formed alveolar wall. In this area, the bone spicules followed the direction of the strained periodontal fibers on the inner surface of the alveolus in the tension zone. New bone deposition was also observed from the osteoid tissue on and between the HAP particles and, as such, promoted the bone growth indirectly.
In conclusion a relatively decreased response of alveolar bone formation and regeneration of periodontal ligament, incidental to experimental tooth movement in both areas was found.
There is a problem as the dynamic aspect must be considered in the regeneration of periodontal ligament and bone formation involved in the healing of periodontal defects implanted with HAP.
