[Histological study on gingival tissue reattachment after periodontal surgery. Effects of hydroxyapatite ceramic implantation to denuded dentin surfaces in rats].

The purpose of this study was to evaluate histological regeneration of epithelial and connective tissue attachment to the denuded dentin surface after hydroxyapatite ceramic granule (HAP) implantation. HAP (particle size 100-300 microns, burn temperature 900 degrees C) were implanted into dehiscent defects of alveolar bone which eliminated about a 1 x 1 mm area at mesial and palatal sites of the upper 1st molar in 20 male Wistar rats. Subsequently the root cementum was removed totally and dentin was denuded. Same osseous defects were formed but HAP was not implanted at any contralateral site for the purpose of control. Results of 8-week examination using light and electron microscopy were as follows: 1. In the HAP group junctional epithelium was regenerated on the denuded dentin surface 2 weeks after implantation and epithelial down growth was less than at the control site. 2. In the HAP group connective tissue reattachment with new cementum formation was observed at 2 to 4 weeks after implantation, the healing period tended to be shorter than at the control site and the connective tissue reattachment level was located more coronally. 3. In ultrastructural findings collagen fiber bundles attached to the denuded dentin surface had fibers continuing around HAP granules.