M7

REACTOR PANEL: MICHAEL F. ZIDE, DDS, AND LEONARD B. KABAN, DMD, MD

Safety and Efficacy of Collagen as a Container for Hydrox- ylapatite Implantation in Rabbits. Z’hayafan Cumara- samy, DDS. University of Minnesota, 515 Delaware Street, SE, Minneapolis, MN 55455 (Kwon H)

Subperiosteal implantation of hydroxylapatite granules in humans is known to be successful. However, an effi- cient delivery system and subsequent stabilization of granules have been areas of deficiency. The purpose of this study was to evaluate eight synthetic varieties of col- lagen and to select the best variety as a potential pack- aging material for the granules to improve delivery, stabi- lization, and integration. A total of 64 male rabbits weighing 4 to 5 lbs were used. They were divided into eight groups, and each group received a different variety of collagen. The materials involved in the evaluation in- cluded empty collagen tubes (C), hydroxylapatite granules (0, Oramite), and granules contained in the col- lagen tubes (H, Heligraft). H was implanted in all eight rabbits-four on the right side and on the left side. C was compared with H in the first four rabbits of each group, and 0 was compared with H in the remaining four rabbits of the same group. Each animal was anesthetized with ketamine HCI 100 mgkg and Rompun 25 mg/kg intramus- cularly. The tibia of each leg was shaved and scrubbed with 50% Betadine solution. Under local anesthesia using 2% Xylocaine with epinephrin 1: lOO,OO, the periosteum was lifted and a tunnel created. After the implantation 4-O vicryl was used for closure. The odd-numbered rabbits of each group were killed on day 30 and the remainder on day 60. Clinical and radiographic evaluations were made to assess stability, i.e., displacement and immobility, fol- lowed by histologic examination for inflammatory re- sponse, fibrotic response, and new bone formation. The patite granules and granules contained in the collagen tubes were implanted in all eight rabbits-four on the right side and four on the left side. C was compared with H in the first four rabbits of each group. and 0 was com- pared with H in the remaining four rabbits of the same group. Each animal was anesthetized with ketamine HCI 100 mg/kg and Rompun 25 mgikg intramuscularly. The tibia of each leg was shaved and scrubbed with 50% Be- tadine, 1.1% less than 0. Osteogenesis to H was 19.2% less than seen for 0, while 0 and C were equal with re- gards to osteogenesis. Heligraft used in group III pro- duced encouraging responses in that there was 10% less inflammation, 16% less fibrosis, and an equal amount of osteogenesis as for Oramite. It is therefore safe to use collagen as used in H in group III. If the variety of col- lagen is not chosen correctly increased inflammation and fibrosis and decreased osteogenesis is seen in collagen packets containing hydroxylapatite. The system of using collagen containers is efficient and has the potential to augment tissue integration of hydroxylapatite granules provided that the collagen is treated to be identical to the type used in group III. Collagen containers for hydroxyl- apatite implantation were found to be safe and efficient.

Effect of Resorbable Calcium Phosphate Ceramic on Tooth Eruption and Development. Stephen E. Feinberg, DDS, PhD. Ohio State University, Columbus, OH 43210 (Vitt M)

Closure of secondary alveolar clefts requires an au-

togenous bone graft. Patient morbidity would be substan- tially reduced if a suitable alloplastic material were used instead of ABG. Because the optimum time for closure is prior to complete tooth eruption, the alloplastic material must not interfere with tooth eruption. It has been dem- onstrated that nonresorbable hydroxylapatite (HA) will prevent tooth eruption and distort tooth development when grafted over an erupting tooth (Feinberg SE, 1985). Resorbable ceramics, such as tricalcium phosphate (TCP), may not have this effect. The purpose of this project was to determine if TCP would interfere with tooth eruption and development in an animal model. Ten kittens three months of age were used in this project. The second and third deciduous mandibular premolars were extracted on the experimental side. The alveolar extrac- tion sockets of the primary teeth were then treated in one of the following ways: 1) packed with HA (Interpore 200); 2) packed with TCP (periOSS): or 3) a normal blood clot was allowed to form without implant placement (sham control). Buccal and lingual flaps were mobilized and closed primarily. The contralateral side was not subjected to surgery and was used to monitor the physiologic tooth eruption pattern of each kitten. The usual age for the shedding of the primary molars is 4 to 6 months of age, with the permanent teeth in position by 5 to 7 months of age. The kittens were killed when the permanent second and third premolars were completely erupted on the con- trol side of the mandible. Tooth development and erup- tion was determined radiographically by comparing the experimental and control sides. The sham control oper- ated side showed normal tooth development and an erup- tion pattern similar to that of the contralateral normal teeth. The surgical procedure to extract the deciduous teeth had no effect on tooth eruption or development. Tooth eruption was impeded in the kittens that received HA grafts. Tooth development was distorted when com- pared to the fully erupted dentition on the control side. The kittens that had TCP grafts exhibited tooth develop- ment and eruption that did not differ from the control side. The tooth morphology was radiographically iden- tical to the control teeth. The final position of the teeth upon complete eruption was similar to the eruptive level of the control dentition. The conclusions of this study are the following: 1) surgical removal of deciduous teeth does not alter tooth eruption or development; 2) HA grafts im- pede normal tooth eruption and distort tooth develop- ment; and 3) TCP has no adverse effects on tooth devel- opment or eruption. The implication of this study is that it may be possible to use resorbable ceramic materials in cleft patients.

This study was supported by NIDR research grant DE07592 and Interpore International.

Craniofacial Reconstruction and Maxillofacial Contour Augmentation with Porous HA and Split Rib Autografts. Ralph E. Holmes, MD. UCSD Medical Center, 225 Dick- inson Street, San Diego, CA 92103 (Hagler HK)

The goals of maxillofacial augmentation and cranial re- construction are contour maintenance and protection. To be an attractive alternative to autografts a porous HA im- plant must demonstrate 1) early bone ingrowth, 2) long- term maintenance of bone ingrowth, and 3) long-term maintenance of dimensional stability. In this study these three inplant parameters were measured and compared to autografts. Bilateral subperiosteal augmentations of the maxillae were performed in 17 adult dogs using implants