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Purpose In February 2011, the Food and Drug Administration issued a postmarket surveillance order to all manufacturers of temporomandibular joint (TMJ) implants in the United States. The objective of the present study was to measure implant subsequent surgical intervention (SSI) among patients who had undergone TMJ reconstruction with the Biomet TMJ replacement system (Zimmer Biomet, Warsaw, IN). Materials and Methods A prospective observational study was conducted by sending a questionnaire to patients who had received a Biomet TMJ replacement system from 1995 to 2010 in the United States. The questionnaire was sent annually from 2012 to 2015. The primary endpoint was the SSIs. SSIs included both device removal and reoperations. Kaplan-Meier survival analysis was used to determine the survivorship, and Cox proportional hazard regression analysis was performed to evaluate the preoperative diagnosis and SSI. Results The mean age at implantation was 46.6 ± 12.5 years, with a gender distribution of 86.1% female. Data from 499 joints in 319 subjects were collected as a part of the survey. The mean follow-up time was 8.6 ± 3.9 years (range, 2-20 years). The first SSI frequency was 11.2% (4.2% removal rate and 7.0% reoperation rate). The survivorship rate (Kaplan-Meier) was 96% at 3 years, 94% at 5 years, and 86% at 10 years. The mean interval to failure using a survival function to determine the time to SSI (Greenwood's formula) was 13.5 ± 0.193 years. The most common causes of SSI included adhesion removal (2.6%; 13 of 498), heterotopic bone/ankylosis (2.0%; 10 of 498), and infection (1.6%; 8 of 498). Conclusions The results from the present study are consistent with the reported survivorship rates for other orthopedic devices (5-year survival for total hip or knee arthroplasty, 95.9 and 97.2%, respectively). The etiology of SSIs in the Biomet TMJ replacement system was primarily secondary to biologic failure (ie, adhesions, heterotopic bone, and infection).

Introduction Although primarily reserved for adult patients, temporomandibular joint (TMJ) total joint reconstructive (TJR) surgery is rarely used in the pediatric population due to its many challenges; it is only performed after all other non-invasive or invasive procedures have been exhausted. Although autogenous grafting has been discussed in the literature, there is very little regarding synthetic or alloplastic materials. In this study, we performed alloplastic TMJ reconstruction on 5 patients with severe ankylosis due to various craniofacial deformities and prior traumatic injuries. Materials and Methods This is a retrospective case series analysis of skeletally immature patients who received alloplastic TMJ reconstruction for recurrent and advanced ankylosis. Our inclusion criteria were as follows: less than 16 years of age, diagnosis of TMJ ankylosis, skeletally immature patients, and unilateral/bilateral total alloplastic TMJ reconstruction. We used the maximum incisal opening (MIO) changes as 1 component to assess for functional improvement. Results Since many of these cases involved gross discrepancies from the normal variants, it was difficult to quantitatively compare the patients with one another. Nevertheless, we used cephalometric analysis to compare pre- and postoperative results on each patient. For this study, we used MIO as our primary assessment: the preoperative average for MIO was 7.4 mm, and the postoperative average 24 mm. Conclusion It is our experience that the use of alloplastic material will not result in harm to either the growth of the mandible or patient's ability to achieve an improved MIO based on our long- and short-term results. These results demonstrate that for even complex craniofacial deformities and traumatic injuries, our patients experienced a significant improvement in MIO, 1 of the main indicators for TMJ function. We conclude that the alloplastic joint can provide a predictable pathway to restore patient's MIO and obviate the need for repeated surgeries, which can be a more challenging alternative with poorer outcomes.

Purpose To assess the safety and efficacy of a stock alloplastic total temporomandibular joint (TMJ) implant system, the Biomet Microfixation TMJ Replacement System. Materials and Methods During a 10-year multicenter clinical trial from 1995 to 2005, 442 Biomet Microfixation TMJ Replacement Systems were implanted in 288 patients (154 bilaterally and 134 unilaterally). Patients were followed at landmark times, including the date of surgery and at 1 month, 3 months, 1 year, 1 year 6 months, and 3 years. The 3 major metrics that were evaluated were preoperative and postoperative pain, interference with eating, and maximal incisal opening. Paired t tests and comparison analyses were used to assess outcomes. Results There was statistically significant improvement in pain level (P = .0001), jaw function (P = .0001), and incisal opening (P = .0001). Although there were complications necessitating the removal of 14 of 442 implants (3.2%), there were no device-related mechanical failures. Conclusions The clinical study presented supports the conclusion that a stock TMJ alloplastic replacement, based on sound orthopedic and biomedical principles, is a safe and efficacious option when alloplastic reconstruction of the TMJ is indicated.

Maxillofacial fractures are relatively rare in the pediatric population. However, the consequences of such fractures can be very profound. Age-specific variations occur with regards to particular fracture types. We review these specific types of fractures, their etiologies, appropriate diagnostic studies, and early management.

Purpose Using finite element (FE) computer model simulation, we compared the mechanical characteristics of the mandible after bilateral sagittal split ramus osteotomy (BSSRO) through the use of 2 different techniques to stabilize the osteotomy. Materials and methods Based on the reconstructed geometry from computed tomography scans of dry adult skull with a mandibular deformity requiring surgical correction, we developed 3-dimensional FE models that simulate BSSRO with 2 different techniques to stabilize the osteotomy. Technique 1 uses 3 bicortical titanium screws. Technique 2 uses a curved titanium plate with 4 monocortical screws. Five different load cases were applied to the mandible after the simulated BSSRO with the mandible being constrained at both temporomandibular joints. To evaluate the efficacy of these 2 stabilization techniques, we compared 1) the resulting deflections at the central incisor, 2) the mechanical stresses developed in the bone in the vicinity of the stabilizing implants, and 3) the mechanical stresses developed within the screw/plating system themselves. Results Technique 1, using 3 bicortical titanium screws, leads to smaller deflections at the central incisor for all 5 load cases, suggesting higher mechanical stability. Technique 1 also leads to lower mechanical stresses in the bone and in the implanted screws, whereas technique 2 is associated with higher values in each of these quantities. Conclusions To stabilize osteotomies after a 3-dimensional simulated BSSRO, 3 bicortical screws forming an inverted-L configuration are shown to offer more effective load transmission in the mandibular construct. This technique, when examined in an FE model, leads to higher stability with lower mechanical stresses in the bone near the bicortical screws.

Introduction: The 4-dimensional facelift is an advanced rhytidectomy technique using a combination of the subperiosteal and multiplanar/multivector facelift techniques simultaneously with CO2 and erbium:YAG laser resurfacing for maximal facial rejuvenation. The combination of these procedures produces a rejuvenation that has synergistic benefits. The facelift alone does not rejuvenate fine rhytids around the mouth and infraorbital regions. In addition, laser resurfacing does not address the rhytids caused by deeper ptotic anatomic structures, nor lines of animation. The 4-dimensional rhytidoplasty provides the ultimate in subtle release of the anatomic facial planes. This concentric release of the various anatomic planes reduces unnecessary tension and unnecessary vascular compromise on any particular layer. This results in increased safety of the technique, allows for simultaneous laser resurfacing, and gives a more natural and improved facial rejuvenation. Materials and Methods: Thirty-two patients (4 males and 28 females) underwent the 4-dimensional facelift between November 1998 and December 1999. This includes simultaneous laser resurfacing and a deep-plane multivector facelift, including an extended subperiosteal release. After all adjunctive procedures had been performed and the superficial musculoaponeurotic system had been stabilized, the redundant preauricular skin was lasered, keeping the energy densities the same, but altering the number of passes. The edges were then trimmed and submitted for histologic examination. Conclusions: The authors are not aware of any previous publications combining all the anatomic planes of the face into a single operation. It has also been the accepted dictum by various experts in the field that laser resurfacing over the undermined flap was a contraindication. However, on the basis of our experiences and results, it is our opinion that this can be done and that the clinical endpoint is safely achieved, resulting in a superior cosmetic result and an assumed increased longevity.

Introduction: Since the introduction of the endoscopic browlift, several techniques have been advocated to improve long-term stability and results. These include extensive undermining of the flap, muscle plication, and a variety of fixation techniques. At our institution, intraoral subperiosteal dissection is used in combination with the laser-assisted endoscopic browlift. No clinical studies have compared flap tension using the different methods of periosteal release. The purpose of this study was to compare scalp tension when the flap was pulled posteriorly 10 mm and 15 mm with and without intraoral subperiosteal release of the midface. Materials and Methods: This study included 37 patients and consisted of 4 men and 33 women. They underwent a laser-assisted endoscopic browlift with general anesthesia or intravenous sedation. Scalp tension was measured with a spring scale. Scalp tension was measured at 6 locations (the incisions over the right and left medial brows, brow heights, and temporal regions). After the laser-assisted endoscopic browlift, measurement of scalp tension at each location was recorded while the scalp was pulled posteriorly 10 mm and then 15 mm. Tensions were measured prior to and after intraoral subperiosteal release of the midface. Tensions at each incision site before and after subperiosteal release were compared using paired t tests. Tensions between the medial brow, brow height and temporal flaps for each side were also compared using paired t tests. Results: Subperiosteal release of the midface significantly reduced tension at every incision site by more than 200 g. The average amount of tension reduction gradually increased from the midline sites to the temporal sites prior to subperiosteal release of the midface. Tension was reduced by more than 300 g at the temporal sites after subperiosteal release of the midface. Conclusions: This study demonstrates that by including intraoral broad subperiosteal detachment of the midface, there is less tension on the flap at all incision sites. Reduced tension and more equally distributed tension would be expected to contribute to better would healing, improved predictability, and assumed longevity of results.

Complications associated with LeFort III osteotomies have led to modifications of the procedure. Attempts to decrease morbidity include performing incomplete osteotomies or eliminating pterygomaxillary dysjunction. The purpose of this study was to determine the amount of tension required for separation of the midface from the pterygoid plates and to observe the fracture patterns. An Instron machine (Instron Corporation, Canton, MA) was used to measure the tension forces in 16 cadaver skulls divided into five groups. The groups varied as to whether the osteotomies were complete and whether pterygomaxillary separation was performed. Specimens with incomplete osteotomies and without pterygomaxillary separation required greater tension forces for separation and exhibited a high percentage (47%) of unfavorable fractures. Because high amounts of tension are required leading to unpredictable separations, we recommend complete osteotomies with pterygomaxillary dysjunction when performing LeFort III osteotomies.

A retrospective review was undertaken of 126 consecutive craniofacial procedures involving a transcranial component, performed at the Children's Medical Center at Dallas, between 1990 and 1994. Standard postoperative axillary temperature measurements were recorded until discharge. Age at surgery of less than 24 months correlated very strongly with a postoperative temperature of greater than 38 degrees C (r = -0.92). The incidence of postoperative fever was high in all age groups, yet there was still a significant difference between the group younger than 2 years and the group in which surgery was performed after the age of 2 years across all postoperative temperature ranges, from >38 degrees C to >39.5 degrees C (p < 0.001, chi-square test). The white blood cell count was elevated above the age-related normal in 67 percent of febrile patients. There was no correlation between type or duration of surgical procedure, length of intensive care or hospital stay, or the need for blood transfusion and the development of a significant postoperative fever. There were minor infectious complications in four patients (3 percent), only one of which was a wound problem related to the surgery. All infectious complications were easily identifiable clinically. There was no mortality or serious infections. The development of postoperative fever, and an elevated white blood cell count, is to be expected in pediatric patients undergoing craniofacial procedures. The routine laboratory investigation of postoperative fever in pediatric craniofacial patients under 2 years of age without procedures involving transgression of the paranasal sinuses is not warranted unless there are associated clinical indicators.

Statement of problem. Though computer-based systems for recording three-dimensional jaw motion and muscle activity during mastication are common, few computer programs are available to analyze the resultant data. Few studies have discussed the variability over time of the many parameters of the masticatory cycle now measurable by computer systems. Purpose. The purposes of this study were to (1) use a custom computer program, (MAS), for analysis of long-term repeated measurements of mandibular motion and muscle activity; (2) determine sex differences for mandibular movements and activity of the muscles involved during mastication; and (3) determine the variability over time and the statistical power of these methods. Materials and methods. Masticatory cycles of 20 normal men and 17 normal women were examined during mastication of a constant bolus at a sampling rate of 500 fps. Measurements included duration of chewing cycle and its component phases, mandibular displacement in three dimensions, and electromyographic activity in the temporalis and masseter muscles. The MAS custom computer program was used for analysis. Two-way repeated measures analysis of variance was used to compare the men with the women over three trials at 0, 6, and 12 months. The variability over time associated with each measurement was also estimated. Results. Timing of the phases of the chewing cycle were most repeatable between trials, whereas lateral excursions and muscle force magnitudes were the least repeatable measures. Durations of total cycle, its slow-open and fast-close phases, were significantly longer for the female group, and their bursts of muscle activity tended to be longer. The amount of vertical mandibular excursion tended to be greater for men. There were no gender-related differences in the amplitude of muscle activity. Conclusions. This study demonstrated that men have significantly shorter chewing cycles with faster velocities than women. Men used significantly greater chewing force than women, although their electromyographic activity levels were equivalent. The masticatory measurements made by the MAS program had differing amounts of variation over time. Total duration of the chewing cycle and amount of opening varied the least, whereas amount of lateral excursion and jaw muscle electromyographic magnitudes exhibited the greatest variation. (J Prosthet Dent 1997;78:179-86.)

Purpose: The purposes of this investigation were 1) to compare the morphology and function of patients with combined vertical maxillary excess (VME) and mandibular retrognathia with that of controls, and 2) to examine how these parameters change after combined maxillary intrusion and mandibular advancement surgery. Patients and Methods: Fifteen female VME/retrognathic patients were compared with 26 female controls before and for up to 3 years after orthognathic surgery. Facial skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyographic activity (EMG) in selected muscles of mastication were measured on all subjects. Where appropriate, one-way analysis of variance (ANOVA) or t-tests were used to compare the patients with controls. Univariate repeated-measures ANOVA was used to study longitudinal changes. Results: Preoperatively, patients' morphologic measurements were characteristic of VME compounded by mandibular retrognathia. At surgery, the maxilla was elevated an average of 2.8 mm, and the mandible was lengthened by an average of 7.1 mm. All of the postoperative morphologic measurements were closer to normal values. The patients' masseter mechanical advantage was significantly lower than that of controls both before and after surgery. Surgically induced changes in mechanical advantage were very small. The patients' maximum range of motion and excursion during mastication were all lower than those of controls before surgery. All measurements of mobility decreased immediately after surgery, with a gradual return to preoperative values. However, even 3 years after surgery, all of the motion measurements remained smaller than those of the controls. Before surgery, the patients had maximum isometric bite forces significantly lower than those of controls. Bite forces increased significantly after surgery, approaching normal values within 2 years. The activity levels in the muscles of mastication during isometric bites were not significantlyaltered by surgery. Conclusions: This study confirms that VME/retrognathia patients suffer from substantial deficiencies in their oromotor function. Surgical correction of this particular type of dentofacial deformity improves both the morphologic and functional deficits. Although some changes were not statistically significant, all were toward normalization of the presurgical values.

Purpose: This study evaluated mandibular motion and bite force in patients with temporomandibular joint disorders after joint surgery. Patients and Methods: Maximum voluntary mandibular motion, maximum excursion during mastication, and maximum bite force were examined in 25 female patients before temporomandibular joint surgery. Their pretreatment performance was compared with that at 6 weeks, 6 months, and 1 year after surgery, and with performance of 26 normal female volunteers. Results: Before surgery, all of the patients' movements and bite forces were smaller than those of controls. One year after surgery, maximum interincisal opening increased significantly, but lateral excursion and protrusion remained unchanged. Maximum bite forces increased significantly and nearly reached control levels. Conclusions: Patients with severe restriction in temporomandibular joint function exhibit general improvements in some mandibular movements and in maximum bite force after surgical treatment.

SUMMARY It is well recognized that the proper correction of many dentofacial deformities produces significant soft-tissue changes that can be predicted with relative accuracy. The orthognathic procedure may improve or rarely worsen a pre-existing soft-tissue relationship. In this article, we have shown that orthognathic surgery and rhinoplasty can be successfully combined, in either a concomitant or delayed fashion, when certain guidelines are followed. As our specialty strives to achieve the best possible outcome for patients, one would have to agree that, although not all nasal changes are predicatable preop- eratively, more refined postoperative results are achieved by the inclusion of adjunctive aesthetic procedures.

Purpose: The purpose of this investigation was to compare morphologic parameters and functional performance between controls and a sample of patients with mandibular retrognathia prior to surgical correction, and to examine how oral motor function adapts after treatment. Patients and Methods: Twenty-four retrognathic female patients were compared with 26 female controls before and up to 3 years after mandibular advancement surgery. Measures of skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyographic activity in the anterior and posterior temporalis and masseter muscles during isometric bites were made on all subjects over time. One-way analysis of variance was used to compare the controls, the patients before surgery, and the patients after surgery. Results: Surgical lengthening of the mandible averaged 7.3 mm, bringing most skeletal measures into the normal range. There were no significant differences in jaw muscle mechanical advantage between patients and controls before surgery, but surgery significantly reduced mechanical advantage of the anterior temporalis and masseter muscles. Jaw hypomobility was apparent at 6 weeks after surgery, but returned to normal values within 12 to 24 months. Before surgery the patients had maximum isometric bite forces less than half those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 years. Before surgery the patients' muscle activity levels per unit of bite force were equivalent to those of controls or somewhat higher. After surgery some of the patients' muscles had significantly lower levels of muscle activity per unit of bite force than did controls. Conclusion: The results of this study suggest that correction of mandibular retrognathia by mandibular advancement surgery produces some significant functional benefits.

Individuals with developmental deformities of the jaws may be less efficient at chewing food. Previous studies have reported masticatory deficiency in patients with such deformities. This study was designed to detect any changes in masticatory performance that accompany orthognathic surgery.Masticatory performance was tested in 18 patients with various jaw deformities before application of orthodontic appliances and 2 to 3 years after surgical correction of their malocclusion. A control group was tested at three 6-month intervals. The subjects chewed carrots and masticatory performance was measured using a standard sieve technique. The Rosin-Rammler equation was used to calculate the median particle size and broadness index of each set of carrots. The number of chewing cycles required for each subject to swallow one piece of carrot was also recorded.A statistically significant difference in median particle size between patients and controls was found both preoperatively and postoperatively (P.05), but no difference in median particle size or broadness index was seen between trials for controls or patients (P.05).It was concluded that before surgery patients have a lower level of performance than controls and surgical correction of the malocclusion does not significantly enhance performance.

Extraoral cranial implant-retained prosthetic reconstructions have been proved to be highly successful. Replacement of the eyes, ears, nose, and larger areas including combined midface defects, which frequently have no other option available, has been done successfully. Burn patients and those with congenital defects are good candidates for this type of reconstruction, especially after autogenous attempts have failed. Cranial implant prosthetic reconstruction should be considered as a viable option for difficult craniofacial defects.

Homologous bone grafts were used in 135 maxillofacial surgical procedures, including acute midfacial fracture repair (n = 77), elective osteotomies of the facial bones (n = 35), secondary correction of traumatic deformities (n = 6), mandibular reconstruction (n = 10), facial bone augmentation (n = 5), and reconstruction of maxillary tumor defects (n = 2). Postsurgical complications occurred in five of the patients. This article reviews the rationale for using homologous bone grafts, their immune response, how they heal, and the risk of transmission of disease.

SUMMARY The objective of this article is to provide the reader with information on the different imaging modalities available for the diagnosis of specific bony orbital injuries. After the history and clinical evaluation, initial radiographic examination should include plain radiographs, and if orbital injuries are suspected, CT scanning is of the most diagnostic value. By combining axial and coronal CT scanning of the orbit and midfacial structures, the full extent of involvement can be appreciated to provide goals for surgical repair. In matching the clinical examination with the imaging findings, a management plan in terms of timing, operative approach, and surgical technique can best be prepared prior to surgery.

This retrospective study analyzed the relationship between complications and substance abuse following mandibular fracture. Over a 2-year period, the records of 352 patients with 589 mandibular fractures were reviewed for methods of treatment and other variables, including chronic abuse of drugs. An overall complication rate of 18.5% was found. Positive associations between complications and chronic abuse of alcohol and nonintravenous and intravenous drugs were found. Intravenous drug abusers had a 30%, nonintravenous drug abusers had a 19%, and chronic alcohol abusers had a 15.5% incidence of complications. Those individuals who did not use any drug chronically had a 6.2% complication rate. The results of this study show that chronic substance abuse can significantly affect treatment outcomes for management of mandibular fractures.

Treatment for patients with craniofacial anomalies always presents a great challenge to orthodontists. Treatment usually requires both comprehensive orthodontic treatment and orthognathic surgery. In this article, we report on a patient with Pfeiffer's syndrome treated by midfacial distraction and comprehensive orthodontics.

SUMMARY Orthognathic surgery produces relatively few intraoperative complications when the procedure is well planned and precisely executed. The majority of problems that occur intraoper- atively result, either directly or indirectly, from inadequate or careless preoperative planning or from technical errors during surgery.

In the last several years the arena of craniomaxillofacial surgery has expanded in scope, and the treatment of these deformities has become more sophisticated. In view of these many changes, the embryology, etiology, pathogenesis, imaging, and treatment of the common craniofacial deformities will be reviewed with their management.

Advances in computer technology have aided in the diagnostic and clinical management of complex congenital craniofacial deformities. The use of stereolithographic models has begun to replace traditional milled models in the treatment of craniofacial deformities. Research has shown that stereolithography models are highly accurate and provide added information in treatment planning for the correction of craniofacial deformities. These include the added visualization of the complex craniofacial anatomy and preoperative surgical planning with a highly accurate three-dimensional model. While the stereolithographic process has had a beneficial impact on the field of craniofacial surgery, the added cost of the procedure continues to be a hindrance to its widespread acceptance in clinical practice. With improved technology and accessibility the utilization of stereolithography in craniofacial surgery is expected to increase. This review will highlight the development and current usage of stereolithography in craniofacial surgery and provide illustration of it use.

In 1851, Virchow was credited as the first to use the term ‘‘craniosynostosis’’ in describing a disorder characterized by an abnormal shape of the skull. He noted that synostosis in the skull restricted growth perpendicular to the direction of the suture and promoted compensatory overgrowth parallel to it. In its basic form, craniosynostosis represents premature suture fusion. It occurs in approximately 1 per 1000 live births in the United States. Two main forms of craniosynostosis exist. The primary form of craniosynostosis, that form amendable to surgical correction, is a result of premature suture fusion. The secondary type of craniosynostosis, that form not amendable to surgical correction, produces an abnormal head shape as a result of an underlying brain abnormality. Craniosynostosis also may be classified as nonsyndromic or syndromic. Most forms of craniosynostosis are isolated and not associated with any other conditions and are therefore nonsyndromic. Syndromic craniosynostosis is covered in another article elsewhere in this issue. The pathogenesis of craniosynostosis is complex and probably multifactorial. Moss theorized that abnormal tensile forces are transmitted to the dura from an anomalous cranial base through key ligamentous attachments, which leads to craniosynostosis such as seen in Apert and Crouzon syndromes. This hypothesis fails to explain the coexistence of craniosynostosis in patients with a normal cranial base configuration. The cause of craniosynostosis may be postulated to be the result of either primary suture abnormalities, sufficient extremes of forces that overcome the underlying expansive forces of the brain, or inadequate intrinsic growth forces of the brain. Cranial vault growth achieves approximately 80% of the adult size at birth and definitive size by 2.5 to 3 years of age. The existence of the six major sutural regions allows for head expansion and transvaginal head deformation. It is often helpful to recall that posterior fontanelle closure (3–6 months) generally proceeds anterior fontanelle closure (9–12 months). Functional considerations The major functional problems associated with craniosynostosis are intracranial hypertension, visual impairment, limitation of brain growth, and neuropsychiatric disorders. In general, the functional problems increase as the number of sutures involved increases. These functional abnormalities are gradual in their development, difficult to detect, and often irreversible in nature.

Normalization of craniofacial malformation in syndromic craniosynostosis patients is an extended process. The care starts at birth and ends in adolescence. Multiple surgeries may be required for each deformity. The relationship among patient, family, and doctor team is important because they must understand the complete processes of management. Psychologists provide an important support mechanism.

Purpose: Ten years ago, the American Association of Oral and Maxillofacial Surgeons membership was surveyed to evaluate the influence that integration of a medical degree might have on oral and maxillofacial training. The intent of the current survey was to reassess the influence a medical degree has had on the specialty over the past 10 years. Patients and Methods: The effects of a medical degree on privileges, referral patterns, and its role in the office, hospital, and academic settings were studied. Biographical data was collected and responses were evaluated for the following groups: 1) the nation as a whole, 2) MD versus non-MD oral and maxillofacial surgeons (OMS), 3) geographic regions of practice, 4) population, 5) number of years in practice, and 6) involvement in academic programs. Results: The results of this survey were similar to the previous one. Substantially different responses were seen between the dual-degree and single-degree OMS as well as differences between geographic locations, years in practice, and academic involvement. MD-DDS and academic OMS again possessed a broader spectrum of privileges than their colleagues. Recently trained OMS again possessed a greater number of privileges than more experienced surgeons. Conclusion: Overall there has been a trend toward increasing surgical privileges over the past 10 years for both single- and dual-degree OMS. The results presented emphasize the need to continually assess the influence that a medical degree has on the specialty. © 2001 American Association of Oral and Maxillafacial Surgeons

Distraction osteogenesis has gained acceptance as a viable modality for lengthening hypoplastic skeletal structures in the maxillofacial region. A case of the application of this technique to advance the maxilla in an unrepaired bilateral alveolar cleft via a transoral approach is presented. The distraction devices were applied bilaterally to the zygomatic buttress region with the activating arms protruding from the oral cavity. A high Le Fort I osteotomy was performed under general anesthesia and, prior to distraction, the three maxillary segments were unified with an occlusal acrylic splint. Activation was begun 6 days after placement, at a rate of 1 mm per day, until the planned maxillary advancement had been achieved. An 8-week period of consolidation was allowed prior to removal of the devices.

Purpose: The purpose of this investigation was to study the long-term effects of orthognathic surgery on mastication in patients before and after four surgical procedures: mandibular advancement, maxillary intrusion, maxillary intrusion with mandibular advancement, and maxillary inferior repositioning. Materials and Methods: The components and timing of mandibular motion, electromyography (EMG), and estimated biting forces during mastication were studied in 61 patients who underwent orthognathic surgery for correction of four different deformities. The data were statistically compared with 38 control subjects using ANOVA. Results: Preoperatively, there were no significant differences in the duration of the chewing cycles and mandibular excursions among the groups, nor did surgery have any affect on these variables. Before surgery, estimated occlusal forces in the patient groups were smaller than controls. Although these appeared to increase after surgery, the increases did not exceed changes in our untreated controls. Conclusions: The results of this study suggest that, with the exception of EMG and occlusal forces, mastication in orthognathic surgery patients is not significantly different from controls either before or after surgery. EMG during mastication, although significantly lower than in controls before surgery, showed significant increases after surgery, but these increases did not bring estimated occlusal forces up to control levels.

Purpose: The purpose of this investigation was 1) to compare functional and morphologic measurements between controls and patients scheduled for anterior or inferior repositioning of the maxilla, and 2) to examine how these patients' oral function adapted after surgery. Patients and Methods: Nine male patients undergoing anterior and/or inferior repositioning of the maxilla were compared with 26 male controls preoperatively and up to 3 years after surgery. Measures of skeletal morphology, mandibular range of motion, maximum voluntary bite force, and levels of electromyographic (EMG) activity in the anterior and posterior temporalis and masseter muscles during isometric bites were made on all subjects over time. One-way ANOVA was used to compare the controls, the patients before surgery, and the patients after surgery. Results: Before surgery, most of the patients had morphologic characteristics of mandibular prognathism and maxillary retrognathism. Surgery made the patients' skeletal morphology similar to controls except for mandibular length, upper facial height, and palatal plane angle, which were significantly greater than those of controls. There were no significant differences in jaw muscle mechanical advantage between controls and patients either before or after surgery. Hypomobility of the jaw was apparent at 6 weeks and 6 months after surgery, but returned to normal values within 1 to 2 years. Before surgery, the patients had maximum voluntary bite forces significantly less than those of controls. Bite forces in patients steadily increased after surgery, approaching significantly higher values than those of controls. Before surgery, patients' muscle activity levels per unit of bite force were not significantly different from those of controls. Most of the patients' muscle activity levels per unit of bite forces at all bite positions showed no significant change after surgery. Conclusions: The results of this study suggest that anterior or inferior repositioning of maxilla produces some significant functional benefits in patients.

Purpose: The purpose of this investigation was 1) to compare morphologic parameters and voluntary bite forces between controls and a sample of patients with mandibular prognathism before surgical correction, and 2) to examine how these patients' bite forces adapt after treatment. Patients and Methods: Twenty-four prognathic patients were compared with 24 controls before and up to 3 years after mandibular setback surgery. Measures of skeletal morphology and maximum isometric bite force were made on all subjects over time. Statistical analysis compared the controls, the patients before surgery, and the patients after surgery. Results: Surgical shortening of the mandible averaged 4.1 mm, bringing most skeletal measures into the normal range. Before surgery, the jaw muscle mechanical advantages for patients were significantly smaller than for controls; surgery did not significantly change this relationship. Before surgery the patients had maximum isometric bite forces that were significantly less than those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 to 3 years. Conclusions: The results of this study suggest that correction of mandibular prognathism by mandibular setback surgery produces some significant functional benefits.

Purpose: The purpose of this investigation was to 1) compare morphological characteristics and functional performance of a sample of patients with vertical maxillary excess (VME) with controls, and to 2) examine how the patients' oral motor function adapts to surgery. Materials and Methods: Fifteen female VME patients were compared with 26 female controls before and up to 3 years after maxillary intrusion surgery. Measures of skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyogram (EMG) activity in some of the muscles of mastication were made on all subjects over time. One-way analysis of variance (ANOVA) was used to compare the controls with the patients before and after surgery. Univariate repeated measures ANOVA was used to study longitudinal changes in the patients. Results: Preoperatively, the patients possessed morphological measurements characteristic of vertical maxillary excess. Superior repositioning of the maxilla averaged 3.3 mm. Concurrently, most skeletal measures were brought closer to normal values. Masseter muscle mechanical advantage was significantly lower in the patients than in controls both before and after surgery (P < .05). There was no significant difference between patients and controls for other biomechanical measurements. Mandibular hypomobility was apparent at 6 weeks after surgery, but returned to control values within 6 to 12 months. Before surgery, the patients had maximum isometric bite forces significantly less than those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 years. Before surgery the patients' muscle activity levels per unit of bite forces were equivalent to those of controls or somewhat lower. After surgery some of the patients' muscles had significantly lower levels of muscle activity per unit of bite force than did controls. Conclusions: The results of this study suggest that correction of vertical maxillary excess with maxillary intrusion surgery improves some characteristic functional deficits.

Purpose: Little is known about the effects of orthodontic treatment on oral motor function. The objective of this report is to evaluate changes in mandibular motion and maximum bite force that occur between the initiation of presurgical orthodontics and its completion before surgery. Patients and Methods: Fifteen patients (9 women, 6 men) with a variety of dentofacial deformities were examined before and after presurgical orthodontics. Mechanical advantage of the muscles and bite points, mandibular range of motion, maximum isometric bite force, and levels of electromyographic (EMG) activity in the anterior and posterior temporalis and masseter muscles during isometric bites were recorded on all subjects over time. Data obtained before and after completion of presurgical orthodontics were statistically compared. Results: Presurgical orthodontics reduced mandibular mobility somewhat, but the amount was not significant. Statistically significant reductions in bite force were noted after orthodontics for incisor, canine, premolar, and molar bite positions. No significant difference in the EMG/bite force slopes was obtained, nor was there any difference in the moment arms of the bite points or the muscles of mastication from orthodontics. Conclusions: This study showed significant changes in measures of oral motor function resulting from orthodontic treatment. A larger study is needed to confirm that these results will be similar in all orthodontic patients. There is no indication that these changes are the result of physiologic alterations of the muscles of mastication. The best current explanation is that these changes result from the pain and discomfort of the orthodontic appliances and the induced malocclusion.

Purpose: To quantify the connective tissue forces generated during surgical lengthening of the mandible. Patients and Methods: Sixty-three patients who had mandibular advancements by sagittal ramus osteotomy were used in this study. Prior to sectioning the rami, the overjet was recorded. After sectioning the rami, a spring-gauge was attached to the mandibular orthodontic wire and pulled anteriorly to determine how much force was necessary to bring the mandibular incisors into a Class I relationship with the maxillary incisors. Aggressive stripping of the perimandibular periosteum and connective tissues on the distal segment was then performed. The amount of force was again recorded. Results: The mean preoperative overjet in the 63 patients was 6 mm (range, 3 to 11 mm). The mean amount of force required to advance the mandible prior to stripping the tissues was 1,498 g compared with a mean of 787 g after stripping (P < .001). There were statistically significant correlations between the preoperative overjet and the prestripping and poststripping force levels (P < .001). There was also a significant relationship between prestripping and poststripping values (P < .001). Conclusion: The results of this study indicate that orthopedic forces are generated by the perimandibular connective tissues following advancement by the mandible. The effect of these forces on the temporomandibular joint should be evaluated in future studies.

Previous studies have indicated that patients scheduled for orthognathic surgery tend to have lower maximum bite forces and exert lower forces during mastication. The effect of these deficits on masticatory performance have not been previously assessed. Masticatory performance was analyzed in four groups: male and female orthognathic surgery patients prior to presurgical orthodontics (n = 12 and 23), and male and female controls (n = 27 and 31). Mastication performance was analyzed by having the subjects chew 5-g pieces of carrot for 20 cycles and measuring the resulting median particle size with a standard sieve method. Masticatory performance showed the same trends as maximum bite force and masticatory forces: male controls had the best and patients the poorest masticatory performance. There was a weak correlation between masticatory performance and maximum bite force at the molar positions. Masticatory performance also weakly correlated to electromyographic signals during mastication of a constant bolus (gummy bears) for all muscles except the left posterior temporalis. Correlations were generally not present or were very weak between masticatory performance, estimated masticatory forces, and muscle efficiency, suggesting that muscle efficiency and forces generated during mastication are not the primary factors that determine masticatory performance. Other factors contributing to a person's ability to chew food might include occlusal relationships and mechanical advantage.

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There has been relatively little study of masticatory forces in dentofacial deformity patients before orthognathic surgery. This study used a mathematical equation based on electromyographic activity (EMG) during mastication and forces obtained during isometric bites to estimate masticatory forces in 55 control subjects and 48 patients. Subjects chewed on a constant bolus while EMG recordings were made bilaterally from the superficial masseter, anterior temporalis, and posterior temporalis muscles. Unilateral isometric bite forces in the first molar position and simultaneous EMGs were recorded in these same subjects. Superficial masseter muscle activity and isometric bite forces were strongly correlated. The slope of masseter EMG versus isometric force was used to estimate the masticatory forces. Males were found to have significantly higher estimated masticatory forces than females.