EFFECT OF CERAMIC GRAFTS ON TOOTH ERUPTION

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Residual maxillary alveolar cleft defects are frequently encountered in cleft palate patients. Correction of the osseous defect with a bone graft is timed to coincide with eruption of the permanent dentition. The bone graft stabilizes the dentoosseous segments, improves alveolar continuity, and allows unerupted teeth in the cleft to erupt through osseous tissue. Patient morbidity and medical expense would be substantially decreased if a synthetic material was used to substitute for the autogenous particulate cancellous bone (APCB) graft from the ilium. Recently calcium phosphate ceramics (CPC) have been widely used as substitute bone grafts in oral and maxillofacial surgery. The two major CPC, the non-resorbable hydroxyapatites (HA) and the resorbable beta tricalcium phosphates (TCP) have been effective in augmentating dento-alveolar ridges and in repair of alveolar bone discontinuity defects. The variability of bioresorbability of the CPC has been though to be secondary to solution-mediated processes of degradation. To date, this still remains a controversial and debated issue. The specific aim of this proposal is to place various CPC in an area of dynamic bone remodeling i.e. over an erupting permanent tooth. We hope to ascertain the effects of the CPC implants i.e. TCP, HA, on active permanent tooth eruption, as well as their bioresorbability. This will be accomplished using 3-4 month old kittens that have had their deciduous mandibular second and third premolars extracted. The extraction sockets will be packed with either, TCP, HA or APCB. Permanent tooth eruption through the implant material will be compared to APCB, sham surgerized kittens that have had teeth extracted but no implants placed and untreated, control kittens with normal tooth eruption patterns. The kittens will be sacrificed at monthly intervals and analyzed radiographically and histologically. Histologic sectioning will be done on frozen mandibles in a cryostat microtome. The pilot study using 2 cats has shown that implantation of HA using the above model has retarded tooth development and eruption. The data obtained from this study will aid in treatment of cleft patients and also establish an animal model to study the interaction between CPC and tooth eruption.