Scientific Poster Session

Conclusion: It is possible to optimally mobilize the maxilla during LeFort I osteotomy without using a chisel to obtain pterygomaxillary separation. Fracture comminu- tion of both the pterygoid plates and the maxillary tuberosity can be avoided. Resultant good visualization of the pterygomaxillary separation allows easy identification and dissection of the greater palatine neurovascular bundle. Fracture of the medial pterygoid plate can be avoided thus minimizing the risk of injury to adjacent vascular structures.

References

Hiranuma, Y., Yamamoto, Y and Iizuka, T.: Strain distribution during separation of the pterygomaxillary suture by osteotomes. J Cranio-Max Fat. Surg. 16:13-17, 1988

Robinson, P. and Hendy, C.: Pterygoid plate fractures caused by LeFort I osteotomy. Br. J Oral Maxillofac Surg. 24:198-202, 1986

Funding provided by Victoria General Hospital and OMS Ressearch fund

Incidence of Infection in a Series of Mandibular Fractures Richard D. Walls, DMD, Dept. of OMS, Emory University, Schl of Post Grad Dent., Atlanta, GA 30322 (Osborne, T.E., Yanagihara, L.C., Bays, R.A.)

Several authors have noted increased incidence of infection and non-union when comparing open reduction (OR) and internal fixation to closed reduction (CR) and intermaxillary fixation (IMF) in the management of mandibular fractures. Moore et al noted infection in 5.4% of those treated with CR and (IMF) and 14.3% of those treated by (OR) and internal fixation.

Retrospective analysis was carried out on 133 patients treated for mandibular fractures by the Emory University Department of Oral and Maxillofacial Surgery at Grady Memorial Hospital over a two year period from January 1987 through December 1988. A total of 211 mandibular fractures were treated in this patient population; however, gunshot wounds were excluded. There were 47 mandibu- lar angle fractures, 65 subcondylar/ramus fractures, 48 parasymphysis/symphysis fractures, and 52 mandibular body fractures. There was a total of 62 OR and 149 CR. The average time between injury and treatment was 3.8 days.

Five mandibular angle fractures, were infected on admission prior to treatment. The time interval between injury and management averaged 15.7 days. All patients were treated by CR and IMF or external biphasic pin fixation. All infections resolved and developed bony union.

Four fractures became infected after treatment. These included one parasymphysis fracture treated by an in- terosseous wire placed transorally with IMF, one body fracture treated with a bone plate placed transcutane-

ously and two mandibular angle fractures treated by third molar extraction with superior border wire fixation and IMF. The average time between injury and treatment was 3.5 days. The overall infected rate was 6.4% for the OR group and 0% for the CR group. Analysis of the fractures infected after treatment revealed (l/21) 4.8% of the fractures treated with inferior border wire and IMF developed infection, (l/20) 5% of the fractures treated with bone plates became infected (2/10) 20% of the fractures treated with third molar extraction, placement of superior border wire and IMF developed infection. None of the fractures treated by CR developed infection. Anatomically 2.8% of the parasymphysis/symphysis frac- tures, 2% of the body fractures, and 4.3% of the mandibu- lar angle fractures developed infection after treatment.

Closed reduction should be the treatment of choice for most mandibular fractures. However, complex and unsta- ble fractures may require open reduction. The use of bone plates or inferior border wire techniques have similar low morbidity rates and should be considered. The use of a superior border wire through a third molar extraction socket should be used with caution since it has the highest infection rate.

References

Moore, G.F., Olson, T.S. and Yonkers, A.J.: Complications of mandibular fractures: A retrospective review of 100 fractures in 56 patients. Neb. Med. J.. 80~120, 1985

Funding source not provided

Hydroxylapatite in Induced Diabetic and Non-diabetic Rats: Histologic Evaluation Mohamed El Deeb, DDS, MS, Univ. of Minnesota School of Dentistry, Dept. of OMS, 7-174, Moos Tower, 5 15 Delaware St., SE, Minneapolis, MN 55455 (Roszkowski, M.T., El Hakim, I.)

Multiple investigative efforts have revealed that diabet- ics have a decreased production of collagen, peripheral vascular occlusion and a higher rate of infection com- pared to healthy patients.* The purpose of this study was to histologically evaluate Calcitite nonporous hydroxylap- atite (HAG) when implanted subcutaneously in uncon- trolled diabetic rats.

This preliminary study used 48 male Sprague-Dawley rats. One group of 24 rats was given Streptozotocin (75mg/kg) to produce the diabetic status of > 250mg/dl blood glucose (ID group). A second group of 24 rats served as non-diabetic controls (ND group). An equiva- lent volume (ICC) of HAG was implanted subcutaneously in each rat’s chest. Subgroups of six rats from the ID and ND groups were killed at three, six, 12 and 24 weeks post-implantation. The implants were removed with the

AAOMS . 1989 143

Scientific Poster Session

surrounding soft tissues and processed for histologic evaluation.

Gross evaluation of the implant sites showed host encapsulation of the implant with some particle displace- ment. H&E and Masson’s Trichrome specimens showed that soft tissue inflammation was mild at each time interval, with a noted decrease in response at six months in ND and a persistent inflammatory reaction in the ID rats. HAG particles were encapsulated by host tissue in all specimens. Collagen maturity and fibroplasia in- creased through time intervals in ND, while the ID rats showed a marked delay in collagen maturity and density. No osteogenesis was observed in any specimen. Dystro- phic mineralization was observed at the HA/tissue inter- face in 37% of ND and 59% of ID specimens.

We conclude that HAG elicited a greater inflammatory response in ID versus ND rats. HAG granules were encapsulated with host fibrous tissue. In ID rats, the host tissue ingrowth appeared less mature and loosely orga- nized at all time intervals when compared to ND samples. Further investigation is required to determine the degree of abnormal collagen synthesis and host reaction in the uncontrolled diabetic model,

References

Goodson, W.H. and Hunt, T.K.: Wound healing and the diabetic patient. Surg Gynecol Obstet 149:602, 1979

Drobec, H.P., Rothstein, S.S., Gumaer, K.I., et al.: Histological observation of soft tissue responses to implanted, multifaceted particles and discs of hydroxylapatite. J Oral Maxillofac Surg 42:143, 1984

Departmental funding provided

Comparison of Autologous and Allogeneic Bone Grafts in Oral and Maxillofacial Surgery Arden K. Hegtvedt, DDS, Univ. of North Carolina School of Dentistry, Dept. of OMS, CB #7450, Chapel Hill, NC 27599-7450 (Turvey, T.A.)

Fifty-eight percent (153) of the patients were female, 42% (145) were male. Females comprised 52% (103) of the autologous group and 71% (66) of the allogeneic group. The average length of hospital stay was not significantly different between the autologous and the allogeneic groups (X*, 2.7 days, & 2.5 days). The length of hospitalization was significantly increased for the autologous iliac (x1 3.7 P 0.05) and rib (xa 4.0 P 0.05) graft groups. Students t-test was used to determine the significance. In 20% (60) of the patients the grafts were placed extraorally. Twenty-six percent (54) of the patients received autologous grafts and 4% (3) of the allogeneic sample had extraoral placement of the bone graft.

Orthognathic cases constituted 52% (158), clefts 21% (64), reconstructive 15% (46), preprosthetic 6% (17), and craniofacial 5% (15) of all grafts. The allogeneic group consisted of 71% (65) orthognathic, 17% (16) prepros- thetic and 12% (11) reconstructive with no cleft or craniofacial cases. The autologous group had 45% (93) orthognathic, 30% (64) cleft, 15% (46) reconstructive, 7% (15) craniofacial and 1% (3) preprosthetic cases. Use of iliac bone grafts in orthognathic surgery has decreased from 32% of all bone grafts in 1984 to zero iliac harvests for correction of dentofacial deformities in 1988.

Complications at the recipient site include: infection, wound dehiscence, non-union, and unacceptable bony contour. Untoward sequellae were not increased when allogeneic bone grafts were utilized. Complications at the donor site included dural exposure, dural perforation, pain, gait disturbance and pneumothorax. Morbidity associated with graft harvest was eliminated in the allogeneic bone graft sample.

Use of iliac grafts for orthognathic surgery has been eliminated by using other less morbid donor sites. When autologous bone grafts are desired, membranous bone from the craniofacial region (cranium, mandible, max- illa) minimizes the morbidity associated with the donor site, Although complications were not increased by the use of allogeneic bone, its use was limited to select orthognathic, preprosthetic and reconstructive proce- dures. These data clearly demonstrate a trend for utiliz- ing bone grafts obtained from donor sites associated with minimal morbidity and reduced hospitalization.

Records of 298 patients (from January 1984-December 1988) who received bone grafts to the maxillofacial skeleton were examined. Age, sex, length of hospitaliza- tion, intra-vs. extra-oral graft placement, type of surgery, donor site, operative and postoperative complications were identified.

Two hundred six patients underwent autologous grafts (120 cranial, 62 iliac, 17 mandibular, 5 rib and 2 maxillary) and in 92 patients allogeneic grafts were placed. The mean age of the bone graft recipient was 24.4 years, 19.9 years for autologous, 34.0 years for allogeneic.

References

Marx, R.E. et al.: The use of freeze-dried allogeneic bone in oral and maxillofacial surgery. J Oral Surgery. 39:264-279, 1981

Allard, R.H.B., Lekkas, C. and Swart, J.G.N.: Autologous versus homologous bone grafting in osteotomies, secondary cleft repairs, and ridge augmentation: a clinical study. Oral Surg Oral Med Oral Path, 64:269-274,1987

Departmental funding provided

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