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Complications of genioplasty done alone or in combination with sagittal split-ramus osteotomy
Complications of genioplasty done alone or in combination with sagittal split-ramus osteotomy Clarence C. Lindquist,
D.D.S.,*
and George Obeid, D.D.S.,**
DEPARTMENT OF ORAL AND MAXILLOFACIAL
Washington,
D.C.
SURGERY, WASHINGTON HOSPITAL CENTER
Thirty-one patients who had genioplasty done alone or in combination with bilateral sagittal split-ramus osteotomy of the mandible (BSSRO) were examined within 12 to 68 months after surgery. Neurosensory tests revealed that 10% of the mental nerves in patients who had had isolated genioplasties showed altered sensation of the lower lip, compared to 28.5% of the nerves in patients who had genioplasties and bilateral sagittal split-ramus osteotomies. However, when questioned, 7 1% of the patients in the latter group indicated awareness of abnormal feeling in the lower lip. Fourteen teeth in isolated genioplasty cases gave an abnormal response to electric pulp testing. The incision lines healed satisfactorily in most patients. Of the intraosseous wires used for fixation, 5.38% were removed 3 to 10 months after surgery. A notch at the osteotomy site on the lower border of the mandible was noted radiographically in 72.5% of the sites. Chin ptosis was noted in one patient. The cosmetic results satisfied 93.6% of the patients. (ORAL SURC ORAL MED ORAL PATHOL 1988;66:13-16)
G
enioplasty, alone or in combination with other orthognathic procedures, is performed either to give the face esthetic harmony or to give the lips an adequate seal. The procedure was first described in 1942 by Hofer,’ who used an extraoral approach. Trauner and Obwegeser2 later described an intraoral modification. Additional contributions to the technique were made by Converse and Wood-Smith3 in 1964 and by Hinds and Kent4 in 1969. Complications such as nerve damage, wound dehiscence, chin ptosis, and bone resorption have been reported.5*6 These complications can be minimized by careful attention to technique. The purpose of this study is to evaluate the operative and postoperative complications of genioplasty when done either as an isolated procedure or in combination with bilateral sagittal split-ramus osteotomy (BSSRO) of the mandible and to correlate these complications with overall patient satisfaction. MATERIAL
AND METHODS
Thirty-one patients who had undergone genioplasty with or without BSSRO between 1981 and 1986 *Senior Attending Surgeon; also in private practice. **Assistant Director of Residency Training Program.
were recalled for follow-up examination a minimum of 1 year after surgery. There were 28 female and three male patients. The mean age was 32 years; range was 14 to 55 years. The average follow-up time was 33 months after surgery, with a range of 12 to 68 months. Of all 31 patients, 29 had advancement genioplasty and two had posterior horizontal movement. Twenty-one patients also had concomitant LeFort I osteotomy. The surgical procedure was done as follows: A 4 cm incision was placed about 1.5 cm inside the wet line of the lower lip. The incision was made through the mucosa and extended inferiorly and posteriorly through the mentalis muscle down to the periosteum. The anterior surface of the mandible was exposed subperiosteally without reflecting tissue from the anterior and inferior aspects of the mental symphysis (Converse and Wood-Smith,3 Hinds and Kent,4 Bell’). The mental nerves were identified but not dissected free, and the lower border below the mental foramina was exposed. The osteotomy, performed with a reciprocating saw, ran from the concavity just above the widest part of the chin, below the incisor apices, to the lower border of the mandible in the premolar or molar region. The insertion of the muscle fibers on the medial surface of the bony chin was maintained. Once the pedicled chin had been 13
14
Lindquist
and Oheid
mobilized, it was moved to the desired position and fixed to the body of the mandible with three or four 26-gauge stainless steel wires. Hematomas over the chin were minimized by placing a pressure dressing over the chin for 6 to 7 days. The study included an evaluation of the operative and postoperative complications. The latter focused on infection, nerve disturbances, wound dehiscence, healing at the lower border between the osteotomized chin and the body of the mandible, chin ptosis. complications caused by the wires, and patient satisfaction. For the purpose of evaluating patient satisfaction and the function of the inferior alveolar nerve, the patients were divided into two groups. Group I included 21 patients who had had genioplasty and BSSRO. Group 11 consisted of 10 patients who had had genioplasty alone. Stability and relapse were not analyzed because our cephalometric radiographics were obtained on different machines and therefore lacked the uniformity needed for accurate comparison. The inferior alveolar nerve function was assessed in two ways. The first was a subjective assessment in the form of a questionnaire. The second was a neurosensory test. In the subjective assessment the patients were asked if they currently had any problems with their faces and jaws as a result of the surgery. The purpose of this question was to determine if patients perceived numbness as a problem. Then the patients were specifically asked about any numbness or altered sensation of the chin and lower lip postoperatively and about the course the altered sensation had taken until the present time. The second part of the assessment consisted of a neurosensory examination of the areas supplied by the terminal branches of the inferior alveolar nerve: the vermilion border, the skin of the lower lip and chin, and the lower anterior teeth. The mechanoreceptors (touch and pressure) were tested by stroking the skin with cotton swabs and also by two-point discrimination with the points of a caliper. The calipers were first set at 10 mm so the patient could feel two points,
Oral Surg July 1988
then were gradually brought closer together until the patient could feel only one point. Normal range of discrimination of distance for the lips and the midline of the chin is 3 to 5 mm; for the lateral aspect of the chin it is 5 to 7 mm (Kawamara and Wessberg?. The nociceptors (pain) were tested with a sharp dental explorer. In the thermoreceptors, we tested only for cold signals. We performed this test by applying the metal end of a dental mirror to the skin and asking the patient what they felt. Finally, the responsiveness of the six lower anterior teeth was tested with a standard electric pulp tester. Two additional maxillary or mandibular teeth were tested for comparison. The lower labial sulcus was checked for wound dehiscence, which was classified as no scar, a simple linear scar, or a widely dehisced scar. The pattern of healing, in the form of a straight, smooth line or a notch on the lower border between the chin and the body of the mandible, was assessed by examination of a panoramic radiograph. Chin ptosis was assessed by clinical examination of the lower border of the mandible for sagging of soft tissue and for exaggeration of the submental crease; these characteristics were evaluated as prominent, absent, or borderline. The patients’ satisfaction was assessed by asking how they and their immediate relatives perceived the cosmetic results and whether the procedure had made any impact on their lives. RESULTS
None of the 3 1 patients had intraoperative complications. The bony osteotomy of the chin and rami split favorably in all cases, and no nerves were severed during surgery. There was no excessive intraoperative hemorrhage. None of the patients became infected in the postoperative period, and there was no breakdown in the incision line. When asked if they had any problem with their chins or jaws, four patients (19%) in group I and one patient (10%) in group II complained of numbness in the lower lip and chin. When asked specifically about such numbness in the immediate postoperative period, 18 patients (85.7%) in group I reported some form of altered sensation; three patients reported complete resolution within 2 months. Seven patients reported no change after an average of 39 months’ follow-up; the range was 25 to 68 months. The remaining eight patients reported some altered sensation, with steady improvement after an average of 3 1 months’ follow-up; the range was 12 to 59 months. In other words, at the time of evaluation 15 patients (71%) in group I were still aware of some form of altered sensation of the lower lip and chin. Two
Volume Number
66 1
patients (20%) in group II reported numbness in the immediate postoperative period; one patient reported resolution of numbness within 4 weeks, and one patient reported no change after 14 months. Altered sensation of the lower lip and chin, as determined by the neurosensory test, occurred in 28.5% of the mental nerves for group I and in 10% of the mental nerves for group II. The results of neurosensory testing are summarized in Tables I and II. It was interesting to note that four of the 15 patients (26.6%) who reported no numbness of the lower lip and chin had, when tested, an abnormal response to pinprick and two-point discrimination. On the other hand, eight of the 16 patients (50%) reported abnormal sensation of lower lip and chin, yet results of their neurologic tests were normal. Vitality tests were done on 122 teeth (70 in group I and 52 in group II). In group I, 14 teeth (20%) supplied by four nerves had no response, and 12 teeth (17.1%) supplied by six nerves had slow response. In group II, two teeth (3.8%) supplied by one nerve were nonresponsive, and 12 teeth (23%) supplied by four nerves showed slow response. In the long term, 14 patients (45%) showed no scar line, 14 patients (45%) showed a normal linear scar line, and three patients (10%) showed some adhesions and a wide scar. The osteotomy site at the lower border of the mandible below the premolar region healed with a notch in 45 sites (72.5%) and in a straight line in 17 sites (27.5%). Chin ptosis or abnormal dropping of the chin was noted in one of the two patients who had had a posterior repositioning of the chin. A total of 112 intraosseous wires were used to fix the chin. Six wires (5.38%) were removed 3 to 10 months after surgery because of discomfort or pain. None was removed as a result of infection. Twenty patients (95%) in group I and nine patients (90%) in group II reported that they were very pleased with the results of their surgery. One patient from each group was uncertain about the results of surgery. When asked about how the immediate family or friends saw the results, 17 patients in group I said that relatives were pleased. The relatives of one patient were uncertain, the relatives of two patients saw no change, and the relatives of one patient found the patient’s appearance worse after the surgery. In group II there were nine positive answers and one uncertain response among relatives and friends. When asked if the surgery had had any impact on their lives, 10 patients out of 21 in group I (47.6%) noted a positive social change. One patient reported a negative effect; she was conscious of her face and did not like to eat in public. The rest saw no change. In
Complications
Table
II. Group II: Genioplasty
Type of test Pinprick 2-Point discrimination Cotton-swab strokes Temperature
nerves tested 20 20 20 20
of
geniop
fasty
15
(n = 10)
Vermilion border 1 1 0 0
Skin lower
of lip I 1 0 0
group II the surgery had a positive impact in three patients out of 10 (30%). Six patients reported no change, and one patient felt a loss of identity. DISCUSSION
The mental nerve is the most important structure to be protected during chin surgery. To assess the postoperative function of this nerve, we have adopted simple neurologic tests that can be used in an office setting. After analyzing the results of these various tests, we have found that stimulating the pain receptors with a dental explorer gives the best indication of the recovery status of the mental nerve. A substantial number of thermoreceptors appeared to have recovered in our patients by the time of the follow-up evaluation. All 3 1 patients felt the cold signal when a dental mirror was applied to the skin of the lower lip and chin. A similar observation was noted by Ferdousi and MacGregor,9 who attributed it to the order of recovery of the different sensory modalities. Temperature is mediated by small-diameter, nonmyelinated nerve fibers, which are less likely to be damaged and which recover more easily than other fibers.‘O* I’ The incidence of altered sensation as evaluated by neural examination in our study was 28.5% of the mental nerves in group I and 10% of the mental nerves in group II. The incidence of altered sensation of the lower lip after genioplasty alone decreased from 20% immediately after surgery to 10% at 14 months’ follow-up. Hohl and Epker5 reported complete resolution of paresthesia in all 11 patients 12 months after surgery. In group I there was a large discrepancy between the abnormal sensation of the lower lip and chin as perceived by the patient and that measured objectively by neurosensory tests (7 1% versus 28.5%, respectively). More sophisticated testing might reduce the discrepancy somewhat; however, the problem is a reflection of the difficulty in quantifying the quality of sensation. This phenomenon was obvious only in the group that had had the BSSRO. The limited amount of manipulation of the mental nerve during genioplasty presumably did not
16
Lindquist
and Obeid
produce these sensory disturbances. On the other hand, the manipulation of the inferior alveolar nerve after BSSRO is such that the reported incidence of paresthesia varies widely; Martis” reports 2.32%, Macintosh” 9%, Freihofer and Petresevic14 22%, and Pepersack and Chausse” 61%. Pepersack and Chausse made an observation similar to ours, notably that 38.5% of their patients who claimed no neurologic abnormalities of the lower lip after BSSRO showed some sensory deficits when the lips were tested. According to the subjective assessment, 16 patients from both groups had residual altered sensation of the lower lip and chin. However, only five of these patients, 3 I%, perceived this altered sensation as a problem. A total of 14 teeth supplied by five nerves had an abnormal response to electric pulp testing in group II. None of these teeth had any preoperative or postoperative clinical symptoms (an indication that they had lost their vitality), and there was no radiologic evidence of periapical abnormality. Damage to the incisal branches of the inferior alveolar nerve could have taken place when the osteotomy cut was made or when the holes were drilled to fix the chin. It was difficult to extract any significant information from the vitality tests done on teeth of patients in group I. Fifty percent of patients whose teeth did not respond to electric pulp testing had normal lip neurosensory tests, and 50% of the patients whose teeth did respond had abnormal neurologic tests of the skin and vermilion border. Chin ptosis was not a problem in our study, perhaps because most cases evaluated were advancement genioplasty. We believe that leaving the periosteum and muscle attachment to the anterior and inferior aspect of the chin will dictate the final placement of the soft tissue chin and thereby minimize the risk of ptosis. Leaving this attachment also maximizes the blood supply to the pedicled chin and thus reduces the chances of resorption.6v’6 Although a notch was noted on the lower border of the mandible in a large number of panoramic radiographs, the notch was not clinically evident and was not a cosmetic concern. The notch is often unavoidable; however, it can be minimized by placing the osteotomy cut as horizontally as possible. Notching is of particular concern in vertical reduction genioplasties when a segment of bone is removed. To avoid such notching the resected segment of bone should have a wedge shape, with its maximum width on the anterior surface of the symphysis and its narrow end at the lower border of the mandible, below the mental nerves.
Oral Surg July 1988
The most significant complication associated with genioplasty done alone or in combination with BSSRO in our study is neurosensory disturbance. The chance of this disturbance increases when the two procedures are combined. Over time, however, our patients became less aware of this disturbance, and most did not perceive it as a problem. We thank Dr. Paul Krogh for the use of some of his clinical material and for his editorial assistance. We also thank Miss Cindy Allyn for her assistance in coordinating this research project and Miss Sally Klemstine for preparation of the manuscript. REFERENCES 1 Hofer 0. Die operative behandlung der alveolaren retraktion des unterkiefers und ihre anwendungsmoglichkeit jur prognathic und mikrogenic. Dtsch Zahn Mund Kieferheilkunde 1942;9:121-32. 2. Trauner R, Obwegeser H. Surgical correction of mandibular prognathism and retrognathia with consideration of genioplasty. ORAL SURG ORAL MED ORAL PATHOL 1957;10:67789. 3. Converse JM, Wood-Smith D. Horizontal osteotomy of the mandible. Plast Reconstr Surg 1964;34:464-71. 4. Hinds ED. Kent JN. Geniooiastv: the versatility of horizontal osteotomy: J Oral Surg 1969;27:690-700. 5. Hohl TH, Epker BN. Macrogenia: a study of treatment results with surgical recommendations. ORAL SURC ORAL MED ORAL PAT&L 1976;41:545-67. 6. Mercuri LE, Laskin DM. Avascular necrosis after anterior horizontal augmentation genioplasty. J Oral Surg 1977; 35:296-8. I. Bell WH. Correction of mandibular prognathism by mandibular setback and advancement genioplasty. Int J Oral Surg 1981;10:221-9. 8 Kawamara P, Wessberg GA. Normal trigeminal neurosensory responses. Hawaii Dent J 1985;16:8-1-l. 9. Ferdousi AM. MacGreaor AJ. The resnonse of the peripheral branches of the trigem;al nerve to trauma. Int J Oral Surg 1985;14:41-6. 10. Sunderland S. Nerves and nerve injuries. 2nd ed. London: Churchill Livingstone, 1978:125. 11. Wyke BD. Principles of general neurology. London: Elsevier, 1969:48-5 1. 12. Martis ES. Complications after mandibular sagittal split osteotomy. J Oral Maxillofac Surg 1984;42:101-7. 13. Macintosh R. Experience with the sagittal osteotomy of the mandibular ramus. J Maxillofac Surg 198 1;9: 15 1. 14. Freihofer H, Petresevic D. Late results after advancing the mandible by sagittal splitting of the rami. J Maxillofac Surg 1975;3:250. 15. Pepersack W, Chausse J. Longterm follow-up of the sagittal . . splitting technique for correction of mandibular prognathism. J Maxillofac Surg 1978;6: 117. 16. Ellis III E, Dechow PC, McNamara JAJ, Carlson DS, Liskiewicz WE. Advancement genioplasty with and without soft tissue pedicle: an experimental investigation. J Oral Maxillofac Surg 1984;42:637-45. Reprint requests to: Dr. G. Obeid Department of Oral and Maxillofacial Washington Hospital Center 110 Irving St., N.W. Washington, DC 20010
Surgery
D.D.S.,*
and George Obeid, D.D.S.,**
DEPARTMENT OF ORAL AND MAXILLOFACIAL
Washington,
D.C.
SURGERY, WASHINGTON HOSPITAL CENTER
Thirty-one patients who had genioplasty done alone or in combination with bilateral sagittal split-ramus osteotomy of the mandible (BSSRO) were examined within 12 to 68 months after surgery. Neurosensory tests revealed that 10% of the mental nerves in patients who had had isolated genioplasties showed altered sensation of the lower lip, compared to 28.5% of the nerves in patients who had genioplasties and bilateral sagittal split-ramus osteotomies. However, when questioned, 7 1% of the patients in the latter group indicated awareness of abnormal feeling in the lower lip. Fourteen teeth in isolated genioplasty cases gave an abnormal response to electric pulp testing. The incision lines healed satisfactorily in most patients. Of the intraosseous wires used for fixation, 5.38% were removed 3 to 10 months after surgery. A notch at the osteotomy site on the lower border of the mandible was noted radiographically in 72.5% of the sites. Chin ptosis was noted in one patient. The cosmetic results satisfied 93.6% of the patients. (ORAL SURC ORAL MED ORAL PATHOL 1988;66:13-16)
G
enioplasty, alone or in combination with other orthognathic procedures, is performed either to give the face esthetic harmony or to give the lips an adequate seal. The procedure was first described in 1942 by Hofer,’ who used an extraoral approach. Trauner and Obwegeser2 later described an intraoral modification. Additional contributions to the technique were made by Converse and Wood-Smith3 in 1964 and by Hinds and Kent4 in 1969. Complications such as nerve damage, wound dehiscence, chin ptosis, and bone resorption have been reported.5*6 These complications can be minimized by careful attention to technique. The purpose of this study is to evaluate the operative and postoperative complications of genioplasty when done either as an isolated procedure or in combination with bilateral sagittal split-ramus osteotomy (BSSRO) of the mandible and to correlate these complications with overall patient satisfaction. MATERIAL
AND METHODS
Thirty-one patients who had undergone genioplasty with or without BSSRO between 1981 and 1986 *Senior Attending Surgeon; also in private practice. **Assistant Director of Residency Training Program.
were recalled for follow-up examination a minimum of 1 year after surgery. There were 28 female and three male patients. The mean age was 32 years; range was 14 to 55 years. The average follow-up time was 33 months after surgery, with a range of 12 to 68 months. Of all 31 patients, 29 had advancement genioplasty and two had posterior horizontal movement. Twenty-one patients also had concomitant LeFort I osteotomy. The surgical procedure was done as follows: A 4 cm incision was placed about 1.5 cm inside the wet line of the lower lip. The incision was made through the mucosa and extended inferiorly and posteriorly through the mentalis muscle down to the periosteum. The anterior surface of the mandible was exposed subperiosteally without reflecting tissue from the anterior and inferior aspects of the mental symphysis (Converse and Wood-Smith,3 Hinds and Kent,4 Bell’). The mental nerves were identified but not dissected free, and the lower border below the mental foramina was exposed. The osteotomy, performed with a reciprocating saw, ran from the concavity just above the widest part of the chin, below the incisor apices, to the lower border of the mandible in the premolar or molar region. The insertion of the muscle fibers on the medial surface of the bony chin was maintained. Once the pedicled chin had been 13
14
Lindquist
and Oheid
mobilized, it was moved to the desired position and fixed to the body of the mandible with three or four 26-gauge stainless steel wires. Hematomas over the chin were minimized by placing a pressure dressing over the chin for 6 to 7 days. The study included an evaluation of the operative and postoperative complications. The latter focused on infection, nerve disturbances, wound dehiscence, healing at the lower border between the osteotomized chin and the body of the mandible, chin ptosis. complications caused by the wires, and patient satisfaction. For the purpose of evaluating patient satisfaction and the function of the inferior alveolar nerve, the patients were divided into two groups. Group I included 21 patients who had had genioplasty and BSSRO. Group 11 consisted of 10 patients who had had genioplasty alone. Stability and relapse were not analyzed because our cephalometric radiographics were obtained on different machines and therefore lacked the uniformity needed for accurate comparison. The inferior alveolar nerve function was assessed in two ways. The first was a subjective assessment in the form of a questionnaire. The second was a neurosensory test. In the subjective assessment the patients were asked if they currently had any problems with their faces and jaws as a result of the surgery. The purpose of this question was to determine if patients perceived numbness as a problem. Then the patients were specifically asked about any numbness or altered sensation of the chin and lower lip postoperatively and about the course the altered sensation had taken until the present time. The second part of the assessment consisted of a neurosensory examination of the areas supplied by the terminal branches of the inferior alveolar nerve: the vermilion border, the skin of the lower lip and chin, and the lower anterior teeth. The mechanoreceptors (touch and pressure) were tested by stroking the skin with cotton swabs and also by two-point discrimination with the points of a caliper. The calipers were first set at 10 mm so the patient could feel two points,
Oral Surg July 1988
then were gradually brought closer together until the patient could feel only one point. Normal range of discrimination of distance for the lips and the midline of the chin is 3 to 5 mm; for the lateral aspect of the chin it is 5 to 7 mm (Kawamara and Wessberg?. The nociceptors (pain) were tested with a sharp dental explorer. In the thermoreceptors, we tested only for cold signals. We performed this test by applying the metal end of a dental mirror to the skin and asking the patient what they felt. Finally, the responsiveness of the six lower anterior teeth was tested with a standard electric pulp tester. Two additional maxillary or mandibular teeth were tested for comparison. The lower labial sulcus was checked for wound dehiscence, which was classified as no scar, a simple linear scar, or a widely dehisced scar. The pattern of healing, in the form of a straight, smooth line or a notch on the lower border between the chin and the body of the mandible, was assessed by examination of a panoramic radiograph. Chin ptosis was assessed by clinical examination of the lower border of the mandible for sagging of soft tissue and for exaggeration of the submental crease; these characteristics were evaluated as prominent, absent, or borderline. The patients’ satisfaction was assessed by asking how they and their immediate relatives perceived the cosmetic results and whether the procedure had made any impact on their lives. RESULTS
None of the 3 1 patients had intraoperative complications. The bony osteotomy of the chin and rami split favorably in all cases, and no nerves were severed during surgery. There was no excessive intraoperative hemorrhage. None of the patients became infected in the postoperative period, and there was no breakdown in the incision line. When asked if they had any problem with their chins or jaws, four patients (19%) in group I and one patient (10%) in group II complained of numbness in the lower lip and chin. When asked specifically about such numbness in the immediate postoperative period, 18 patients (85.7%) in group I reported some form of altered sensation; three patients reported complete resolution within 2 months. Seven patients reported no change after an average of 39 months’ follow-up; the range was 25 to 68 months. The remaining eight patients reported some altered sensation, with steady improvement after an average of 3 1 months’ follow-up; the range was 12 to 59 months. In other words, at the time of evaluation 15 patients (71%) in group I were still aware of some form of altered sensation of the lower lip and chin. Two
Volume Number
66 1
patients (20%) in group II reported numbness in the immediate postoperative period; one patient reported resolution of numbness within 4 weeks, and one patient reported no change after 14 months. Altered sensation of the lower lip and chin, as determined by the neurosensory test, occurred in 28.5% of the mental nerves for group I and in 10% of the mental nerves for group II. The results of neurosensory testing are summarized in Tables I and II. It was interesting to note that four of the 15 patients (26.6%) who reported no numbness of the lower lip and chin had, when tested, an abnormal response to pinprick and two-point discrimination. On the other hand, eight of the 16 patients (50%) reported abnormal sensation of lower lip and chin, yet results of their neurologic tests were normal. Vitality tests were done on 122 teeth (70 in group I and 52 in group II). In group I, 14 teeth (20%) supplied by four nerves had no response, and 12 teeth (17.1%) supplied by six nerves had slow response. In group II, two teeth (3.8%) supplied by one nerve were nonresponsive, and 12 teeth (23%) supplied by four nerves showed slow response. In the long term, 14 patients (45%) showed no scar line, 14 patients (45%) showed a normal linear scar line, and three patients (10%) showed some adhesions and a wide scar. The osteotomy site at the lower border of the mandible below the premolar region healed with a notch in 45 sites (72.5%) and in a straight line in 17 sites (27.5%). Chin ptosis or abnormal dropping of the chin was noted in one of the two patients who had had a posterior repositioning of the chin. A total of 112 intraosseous wires were used to fix the chin. Six wires (5.38%) were removed 3 to 10 months after surgery because of discomfort or pain. None was removed as a result of infection. Twenty patients (95%) in group I and nine patients (90%) in group II reported that they were very pleased with the results of their surgery. One patient from each group was uncertain about the results of surgery. When asked about how the immediate family or friends saw the results, 17 patients in group I said that relatives were pleased. The relatives of one patient were uncertain, the relatives of two patients saw no change, and the relatives of one patient found the patient’s appearance worse after the surgery. In group II there were nine positive answers and one uncertain response among relatives and friends. When asked if the surgery had had any impact on their lives, 10 patients out of 21 in group I (47.6%) noted a positive social change. One patient reported a negative effect; she was conscious of her face and did not like to eat in public. The rest saw no change. In
Complications
Table
II. Group II: Genioplasty
Type of test Pinprick 2-Point discrimination Cotton-swab strokes Temperature
nerves tested 20 20 20 20
of
geniop
fasty
15
(n = 10)
Vermilion border 1 1 0 0
Skin lower
of lip I 1 0 0
group II the surgery had a positive impact in three patients out of 10 (30%). Six patients reported no change, and one patient felt a loss of identity. DISCUSSION
The mental nerve is the most important structure to be protected during chin surgery. To assess the postoperative function of this nerve, we have adopted simple neurologic tests that can be used in an office setting. After analyzing the results of these various tests, we have found that stimulating the pain receptors with a dental explorer gives the best indication of the recovery status of the mental nerve. A substantial number of thermoreceptors appeared to have recovered in our patients by the time of the follow-up evaluation. All 3 1 patients felt the cold signal when a dental mirror was applied to the skin of the lower lip and chin. A similar observation was noted by Ferdousi and MacGregor,9 who attributed it to the order of recovery of the different sensory modalities. Temperature is mediated by small-diameter, nonmyelinated nerve fibers, which are less likely to be damaged and which recover more easily than other fibers.‘O* I’ The incidence of altered sensation as evaluated by neural examination in our study was 28.5% of the mental nerves in group I and 10% of the mental nerves in group II. The incidence of altered sensation of the lower lip after genioplasty alone decreased from 20% immediately after surgery to 10% at 14 months’ follow-up. Hohl and Epker5 reported complete resolution of paresthesia in all 11 patients 12 months after surgery. In group I there was a large discrepancy between the abnormal sensation of the lower lip and chin as perceived by the patient and that measured objectively by neurosensory tests (7 1% versus 28.5%, respectively). More sophisticated testing might reduce the discrepancy somewhat; however, the problem is a reflection of the difficulty in quantifying the quality of sensation. This phenomenon was obvious only in the group that had had the BSSRO. The limited amount of manipulation of the mental nerve during genioplasty presumably did not
16
Lindquist
and Obeid
produce these sensory disturbances. On the other hand, the manipulation of the inferior alveolar nerve after BSSRO is such that the reported incidence of paresthesia varies widely; Martis” reports 2.32%, Macintosh” 9%, Freihofer and Petresevic14 22%, and Pepersack and Chausse” 61%. Pepersack and Chausse made an observation similar to ours, notably that 38.5% of their patients who claimed no neurologic abnormalities of the lower lip after BSSRO showed some sensory deficits when the lips were tested. According to the subjective assessment, 16 patients from both groups had residual altered sensation of the lower lip and chin. However, only five of these patients, 3 I%, perceived this altered sensation as a problem. A total of 14 teeth supplied by five nerves had an abnormal response to electric pulp testing in group II. None of these teeth had any preoperative or postoperative clinical symptoms (an indication that they had lost their vitality), and there was no radiologic evidence of periapical abnormality. Damage to the incisal branches of the inferior alveolar nerve could have taken place when the osteotomy cut was made or when the holes were drilled to fix the chin. It was difficult to extract any significant information from the vitality tests done on teeth of patients in group I. Fifty percent of patients whose teeth did not respond to electric pulp testing had normal lip neurosensory tests, and 50% of the patients whose teeth did respond had abnormal neurologic tests of the skin and vermilion border. Chin ptosis was not a problem in our study, perhaps because most cases evaluated were advancement genioplasty. We believe that leaving the periosteum and muscle attachment to the anterior and inferior aspect of the chin will dictate the final placement of the soft tissue chin and thereby minimize the risk of ptosis. Leaving this attachment also maximizes the blood supply to the pedicled chin and thus reduces the chances of resorption.6v’6 Although a notch was noted on the lower border of the mandible in a large number of panoramic radiographs, the notch was not clinically evident and was not a cosmetic concern. The notch is often unavoidable; however, it can be minimized by placing the osteotomy cut as horizontally as possible. Notching is of particular concern in vertical reduction genioplasties when a segment of bone is removed. To avoid such notching the resected segment of bone should have a wedge shape, with its maximum width on the anterior surface of the symphysis and its narrow end at the lower border of the mandible, below the mental nerves.
Oral Surg July 1988
The most significant complication associated with genioplasty done alone or in combination with BSSRO in our study is neurosensory disturbance. The chance of this disturbance increases when the two procedures are combined. Over time, however, our patients became less aware of this disturbance, and most did not perceive it as a problem. We thank Dr. Paul Krogh for the use of some of his clinical material and for his editorial assistance. We also thank Miss Cindy Allyn for her assistance in coordinating this research project and Miss Sally Klemstine for preparation of the manuscript. REFERENCES 1 Hofer 0. Die operative behandlung der alveolaren retraktion des unterkiefers und ihre anwendungsmoglichkeit jur prognathic und mikrogenic. Dtsch Zahn Mund Kieferheilkunde 1942;9:121-32. 2. Trauner R, Obwegeser H. Surgical correction of mandibular prognathism and retrognathia with consideration of genioplasty. ORAL SURG ORAL MED ORAL PATHOL 1957;10:67789. 3. Converse JM, Wood-Smith D. Horizontal osteotomy of the mandible. Plast Reconstr Surg 1964;34:464-71. 4. Hinds ED. Kent JN. Geniooiastv: the versatility of horizontal osteotomy: J Oral Surg 1969;27:690-700. 5. Hohl TH, Epker BN. Macrogenia: a study of treatment results with surgical recommendations. ORAL SURC ORAL MED ORAL PAT&L 1976;41:545-67. 6. Mercuri LE, Laskin DM. Avascular necrosis after anterior horizontal augmentation genioplasty. J Oral Surg 1977; 35:296-8. I. Bell WH. Correction of mandibular prognathism by mandibular setback and advancement genioplasty. Int J Oral Surg 1981;10:221-9. 8 Kawamara P, Wessberg GA. Normal trigeminal neurosensory responses. Hawaii Dent J 1985;16:8-1-l. 9. Ferdousi AM. MacGreaor AJ. The resnonse of the peripheral branches of the trigem;al nerve to trauma. Int J Oral Surg 1985;14:41-6. 10. Sunderland S. Nerves and nerve injuries. 2nd ed. London: Churchill Livingstone, 1978:125. 11. Wyke BD. Principles of general neurology. London: Elsevier, 1969:48-5 1. 12. Martis ES. Complications after mandibular sagittal split osteotomy. J Oral Maxillofac Surg 1984;42:101-7. 13. Macintosh R. Experience with the sagittal osteotomy of the mandibular ramus. J Maxillofac Surg 198 1;9: 15 1. 14. Freihofer H, Petresevic D. Late results after advancing the mandible by sagittal splitting of the rami. J Maxillofac Surg 1975;3:250. 15. Pepersack W, Chausse J. Longterm follow-up of the sagittal . . splitting technique for correction of mandibular prognathism. J Maxillofac Surg 1978;6: 117. 16. Ellis III E, Dechow PC, McNamara JAJ, Carlson DS, Liskiewicz WE. Advancement genioplasty with and without soft tissue pedicle: an experimental investigation. J Oral Maxillofac Surg 1984;42:637-45. Reprint requests to: Dr. G. Obeid Department of Oral and Maxillofacial Washington Hospital Center 110 Irving St., N.W. Washington, DC 20010
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