Abstract Session IV: Orthognathic Surgery
ture during surgery, paresthesia and relapse. Recently, rigid fixation of the osteotomy segments has been utilized to reduce relapse and this has been shown to be very effective. The purpose of this study was twofold: 1) to determine where fusion of the buccal and lingual cortices of bone occurs in the upper ramus, and 2) to measure cortical bone thicknesses in the retromolar area to determine if there is an advantage, based on cortical thickness, to placement of bone screws for rigid fixation at the external oblique ridge versus placement at the inferior border. Fifty dried human mandibles were sectioned vertically in six locations mediolaterally, perpendicular to the body or ramus and to the occlusal plane, beginning at the distal root of the second molar and extending to near the posterior border of the mandible. In the ramus, measurements were made to locate vertically the point of fusion of the buccal and lingual cortical plates relative to the lingula and the sigmoid notch. The point of fusion occurred a mean of 7.5 to 13.3 mm above the lingula. Only 2 percent of cases had fusion at or below the level of the lingula in the anterior ramus, while in the posterior ramus 6.1 percent of cases were fused at that level. At a level of half-way from the lingula to the sigmoid notch, 20 percent of cases had fusion at or below that level in the anterior ramus, while in the posterior ramus, the incidence was as high as 39 percent. The vertical level of the medial horizontal osteotomy should be at the tip of the lingula. A higher level of cut may be associated with an increased difficulty of splitting or incidence of unfavorable fracture. At the anterior three section representing the retromolar area and anterior ramus, cortical bone thicknesses were measured at the external oblique ridge and 5 mm above the inferior border. The buccal and lingual cortices were found to be significantly (pc.001) thicker at the external oblique ridge than at the inferior border. Bone screws for rigid fixation of mandibular osteotomies, as well as bone plates for treatment of mandibular angle fractures, should be placed at the external oblique ridge whenever possible, in preference to the thinner cortical bone near the inferior border.
References Rajchel, J., Ellis, E. and Fonseca, R.J.: The Anatomical Location of the Mandibular Canal: Its Relationship to the Sagittal Ramus Osteotomy. Int J. Adult Orthod and Orthognathic Surg., 1:37-47, 1986 Bremer, G.: Measurements of Special Significance in Connection with Anesthesia of the Inferior Alveolar Nerve. Oral Surg Oral Med Oral Pathol5:966-988, 1952
Funding provided by Baylor College of Dentistry 98
A Review of 144 Cranial Bone Grafts Kenneth C. Blankstein, DMD, MD, Univ. of North Carolina, School of Dentistry, Dept. of OMS, CB#7450, Chapel Hill, NC 27599-7450 (Turvey, T.A.) Bone grafting to the maxillofacial complex is essential for comprehensive management of alveolar clefts, certain dentofacial deformities, maxillofacial continuity defects and for some facial contouring procedures. The purpose of this report is to retrospectively review 144 cranial harvest patients for graft success and donor site morbidity as reflected by duration of hospital stay and donor site blood loss. Of the patients reviewed, 36 had craniofacial surgery (intracranial procedures) and 108 had maxillofacial surgery. The patients undergoing intracranial procedures (36) were eliminated from further investigations since the nature and extent of surgery exceeded those undergoing isolated maxillofacial surgical procedures. The maxillofacial surgery patients (108) were grouped according to surgical procedures: closure of alveolar cleft with oral nasal fistula closure (43); alveolar cleft with oral nasal fistula plus lip, nose or palate revision (8); alveolar cleft and concomitant maxillary osteotomy (5); single jaw osteotomy (28); two jaw osteotomy (20); continuity defects (1); esthetic contour grafting (3). Patients ranged from 6-65 (mean 15.6 yrs) 68 males and 42 females. Hospital stay ranged from 28.8 hours (+/-.313 days) for those patients having less surgical intervention i.e., closure of alveolar clefts and oral nasal fistula, to 67 hours (+/- .836 days) for two jaw osteotomies. The difference in hospital stay was a reflection of the extent of surgery and not graft site morbidity. Blood loss recorded (89 patients) for the actual harvest of cranial bone averaged 52cc (range 2Occ-200~~). Complications associated with this procedure are two: dural exposure and dural tear. Twelve of 144 patients (8.3%) had one of these complications. Dural tears are most significant since hematoma, or infection, are potential sequelae. Only 5 patients (3.47%) had dural tears. Closure of these tears were performed with vicryl sutures and subsequently none of the patients developed any neurological or other sequelae. Hospital stay was not prolonged in these patients as a consequence of the dural tear. Infection, wound dehiscence, alopecia or hematoma were not seen in any patients. Good surgical results were achieved in all but 2 patients (98.1%). Sinusitis and Sickle Cell Anemia were thought to contribute to the demise of these grafts. Cranial bone is successfully grafted to the face and harvested with low morbidity. Short hospital stay and minimal pain and blood loss are major advantages for its use. Since two surgical teams cannot work simultaneously, the disadvantage is the increased time required to harvest the bone (45 min). AAOMS
.
1989
Abstract
Brammer,
References Tessier, P.: Autogenous bone grafts taken from the calvarian for facial and cranial applications. Clinics of Plast Surg, Vol 9, No 4, Oct. 1982 Harsha, B.: Use of autologous surgery. JOMS 44:l l-15, 1986 Departmental
funding
cranial
bone grafts
provided
Larry M. Wolford, DDS, Baylor College of Dentistry and Baylor Univ. Med. Ctr., Dallas, TX (Sinclair, P., Chemello, P., Satrom, K.)
The purpose of this study was to compare the stability of rigid versus skeletal wire fixation (SWF) for treatment of patients with vertical maxillary excess combined with A-P mandibular deficiency. Thirty-five patients were evaluated in this study. All patients had simultaneous maxillary and mandibular osteotomies to correct their skeletal facial deformities. Twenty-six of the patients had rigid fixation (RF), and nine patients had SWF. Twentyseven cephalometric parameters were evaluated on cephalometric x-rays taken before surgery, immediate postsurgery and at the longest possible post-operative treatment (mean I5 months). The results of this experiment revealed the following: 1. Even though the maxillary RF sample was advanced I .6 mm more than the SWF sample, it showed less mean relapse in the anteroposterior direction. 2. The maxillary inferior relapse for the rigid fixation sample (0.1 mm anteriorly, and 0.2 mm posteriorly) was much less than the skeletal wire fixation (0.8 mm anteriorly, 0.4 mm posteriorly). 3. The A-P relapse value for the advanced mandible was 26% with the use of SWF and 6% with the use of RF. 4. The RF maintained better control of proximal segment rotation and increased the overall stability for mandibular advancement. 5. The SWF showed a greater decrease in the length of the proximal segment than the RF. 6. Measurement of the cephalometric points representing resting muscle length indicated a propensity for the stretched muscles to relapse back to within 5% of their original length. 7. Both groups showed a long-term change in the hyoid bone position and head posture as a result of the surgery. We conclude from this study that rigid fixation, in general, resulted in better post-operative skeletal stability than skeletal wire fixation. References Aragon, S.B., Van Sickels, J.E.: Mandibular Range of Motion with Rigid/Nonrigid Fixation. Oral Surg, 63:408-411, 1987
.
1989
IV: Orthopnathic
Surgery
J., Finn, R., Bell, W.H., Sinn, D., Reisch, J. and Dana, K.:
Stability After Bimaxillary Surgery to Correct Vertical Excess and Mandibular Deficiency. J Oral Surg 38: 664-670,
Maxillary 1980
in maxillofacial
The Efect of Rigid and Skeletal Wire Fixation on the Stability of Double Jaw Surgery
AAOMS
Session
Skeletal Stability After LeFort I Maxillary Advancement in Patients with Unilateral Cleft Lip and Palate Mark P. Ewing, DDS, The Hospital for Sick Children, Room 5430, 555 University Ave., Toronto, Ontario, Canada M5G 1X8 (Posnick. J.C.) Short and long term outcomes in patients who had unilateral cleft lip and palate (UCLP) and underwent orthognathic surgery were investigated to determine amount and timing of relapse, correlation between advancement and relapse, effect of performing multiple jaw procedures, effect of different types of bone graft, effect of pharyngoplasty in place at the time of osteotomy and effectiveness of various methods of internal fixation. Longitudinal records of thirty (skeletally mature) patients (age 13.4 to 23.3 years, mean i 8.0 years) who had UCLP and underwent LeFort I advancement at the Hospital for Sick Children ( 1973- 1984) were examined. All patients had lateral cephalograms taken preoperatively and postoperatively (immediately and after 6 weeks, 6 months, one year and two years). These tracings were digitized and entered into a Hewlett-Packard 9836 minicomputer. No significant difference in outcome was seen between patients who had maxillary surgery alone and those who had operations in both jaws, nor did the outcome vary significantly with the type of autogenous bone graft used or the segmentalization of the LeFort I osteotomy (P>O.O5). Mean “effective” advancement was greater immediately and two years after surgery in those patients who did not have a pharyngoplasty in place before the operation. Advancement was also greater immediately and after two years in the miniplate fixation group than in patients with direct-wire fixation. Mean downward (vertical) displacement was 2.6 mm with relapse of 1.4 mm after two years. Amounts of relapse and advancement (horizontal) or displacement (vertical) did not correlate significantly.
References Willmar, K.: On LeFort I osteotomy. A follow-up study of 106 operated patients with maxillofacial deformity &and J Plast Reconstr SURg. 12: (Suppl. l), 1974. Araujo, A., Schendel, S.A., Wolford, L.M. and Epker. B.N.: Total maxillary advancement with and without bone grafting. J Oral Surg. 36:849. 1978. Departmental
funding provided 99