Douglas P. Sinn

Recovery of neurosensory function following orthognathic surgery

The purpose of this study was to prospectively define the recovery of touch discrimination following four commonly performed surgical procedures in 22 consecutive patients with no previous maxillofacial surgery. The surgical groups studied were Le Fort I osteotomy (LEFORT; n = 13), sagittal split ramus osteotomy (SSRO; n = 6), intraoral vertical ramus osteotomy (IVRO; n = 9), and isolated genioplasty (GENIO; n = 5). Neurosensory function was assessed by three different testing modalities which included static light touch (SLT), moving touch discrimination (MTD), and two-point discrimination (TPD). Cutaneous sensation of the lower lip and chin were examined for the mandibular procedures, whereas the infraorbital and upper lip regions were evaluated following maxillary surgery. Immediately following surgery, each group varied in both the incidence and magnitude of neurosensory deficits (NSD). The SSRO group had the highest percentage of sites with immediate postsurgical NSD to both SLT (72%) and MTD (67%), followed by the LEFORT (SLT = 50%, MDT = 58%), GENIO (SLT = 27%, MTD = 6%), and IVRO groups (SLT = 11%, MTD = 18%), respectively. Each group also varied in the severity of the initial postoperative deficit as measured by SLT, with the SSRO group showing the greatest deficit followed by the LEFORT, GENIO, and IVRO groups. During the 6-month recovery period each group approached preoperative levels of sensation at a different rate. The LEFORT group recovered most rapidly, with few anatomic sites showing NSD (SLT = 20%, MTD = 5%) at the 1-month postoperative examination, and the majority of the group (96%) returned to preoperative sensation by 3 months following surgery. The SSRO group recovered more slowly, with approximately half of the group demonstrating a deficit (SLT = 50%, MTD = 59%) at 1 month, which diminished to about one fourth of the sites (SLT = 25%, MTD = 5%) by 3 months. Most of the SSRO group (90%) exhibited no residual deficit 6 months following surgery. The IVRO group had few sites with immediate NSD (SLT = 11%, MTD = 15%). In none of the surgical groups was a statistically significant correlation found between the severity of the initial NSD and length of time to complete recovery.

Relationship of substance abuse to complications with mandibular fractures

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.

Predictability of upper lip soft tissue changes with maxillary advancement

To improve predictability of the esthetic (soft tissue) results after maxillary advancement surgery, a better understanding of the relationships between the dental osseous movement and overlying soft tissue response is essential. Twenty-one adult patients who underwent isolated maxillary advancement via LeFort I osteotomies without adjunctive nasal soft tissue procedures and/or V-Y closure of the vestibular incision were studied. Homogeneity of the patient population was ensured by selecting cases with less than 2 mm vertical change. The mean maxillary advancement and mean change in Sn was calculated for these 21 patients. Additionally, the 21 patients were subdivided into two groups based on lip thickness: group 1 (lips between 10 and 17 mm thick) and group 2 (greater than 17 mm thick). In each patient group a linear regression (LR) was determined on the magnitude of maxillary advancement (MMA) to the change in soft tissue subnasale (Sn) and on the ratio of Sn change to bone move. The results using mean data showed that the relationships produce significantly high standard deviations; thus, a general correlation between change in soft tissue position to bony advancement cannot be made. Individuals with thin lips (12 to 17 mm) had a good correlation between the magnitude of bony move and amount of soft tissue change. However, increased lip thickness (greater than 17 mm) produced a less predictable correlation between soft and hard tissue changes. All lips thinned around 2 mm when compared with preoperative values. Lip thickness stabilized at approximately 6 months postoperatively.

Complications of nonrigid fixation of mandibular angle fractures

This retrospective study analyzed complications in 96 patients with 99 mandibular angle fractures treated during a 3-year period with either closed reduction or nonrigid means of fixation combined with maxillomandibular fixation. An overall complication rate of 17% occurred. Infection was the most common complication, occurring in 17 fractures. Thirteen fractures had infection as the only complication; in the remaining four patients, infection was combined with malunion/malocclusion. The results of this study show that mandibular angle fractures in an inner-city population are associated with a high incidence of postsurgical complications.

Biomet Microfixation Temporomandibular Joint Replacement System: A 3-Year Follow-Up Study of Patients Treated During 1995 to 2005

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.

Masticatory performance, muscle activity, and occlusal force in preorthognathic surgery patients☆

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 persons ability to chew food might include occlusal relationships and mechanical advantage.

Recovery of mandibular mobility following orthognathic surgery

The aim of this prospective study was to define the patterns of recovery of mandibular mobility following three commonly performed orthognathic surgical procedures. Twenty-two consecutive patients undergoing either isolated Le Fort I osteotomy (LE FORT; n = 7), sagittal split ramus osteotomies (SSRO; n = 7), or intraoral vertical ramus osteotomies (IVRO; n = 9) were studied. LE FORT and SSRO patients had no mandibular immobilization, whereas IVRO patients were immobilized by dental fixation for 3 weeks. Mandibular mobility was assessed by measurement of maximal mandibular opening (MMO) and lateral and protrusive excursions. No significant difference in MMO was observed between groups prior to surgery (LE FORT, 47.0 mm; SSRO, 50.7 mm; IVRO, 54.5 mm). A significant reduction in MMO occurred immediately after surgery in the LE FORT and SSRO groups and at release of fixation in the IVRO group. Each group returned to presurgical levels of mandibular mobility at a different rate following surgery. LE FORT patients recovered quickly, regaining 83% (mean, 38.7 mm) of MMO by 1 month and exceeded preoperative levels (mean, 49.6 mm) by 6 months. SSRO patients showed hypomobility (mean, 23.5 mm) after 1 month, with significant improvement in MMO (mean, 38.0 mm) at 2 months, and nearly complete recovery (96.2%; mean, 48.8 mm) at 6 months. IVRO patients recovered rapidly after release of dental fixation, achieving 78% (mean, 39.8 mm) of preoperative MMO at 2 months. This study shows that significant differences in recovery patterns of mandibular mobility exist between surgical procedures. The clinician should be aware of these differences in recovery patterns in defining goals for individual patient rehabilitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical outcomes using bioabsorbable plating systems in pediatric craniofacial surgery

The purpose of this study was to evaluate the surgical outcomes of the 1.5-mm LactoSorb plating system (Walter Lorenz Surgical, Inc., Jacksonville, FL, U. S. A.) used to stabilize the osteotomized calvarial bone in pediatric patients who have undergone craniofacial surgery. The records of 33 consecutive pediatric patients who underwent craniofacial surgery from January 1997 through December 1997 were reviewed. There were 18 male and 15 female patients, and the age ranged from 4 months to 12 years. Patients were followed-up at 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. For those patients reviewed, the following information is included: age, sex, diagnosis, surgical procedures, number and size of LactoSorb plates and screws used in each patient, operative difficulty of the screws and the heat pack, and postoperative complications, including wound healing, palpability, and infection. The LactoSorb plating system was used to stabilize the osteotomized calvarial bones in 33 patients who were diagnosed with: 1) craniosynostosis, 2) hydrocephalus, 3) fibrous dysplasia, or 4) cranial deformation. Orbital rim advancement and anterior cranial vault reshaping were performed in 17 patients. Posterior cranial vault reshaping, orbital rim advancement, and anterior cranial vault reshaping were performed in eight patients. Posterior cranial vault reshaping only was performed in seven patients. Excision of fibrous dysplasia from temporal bone was performed in one patient. One patient had a postoperative wound infection, and LactoSorb plates were palpable postoperatively in four patients. The LactoSorb plating system provided adequate rigidity for stabilizing the osteotomized calvarial bone during surgery and maintained adequate rigidity after surgery during the bone healing period before absorption. This plating system showed satisfactory results in pediatric craniofacial surgery patients.

A preliminary study of maximum voluntary bite force and jaw muscle efficiency in pre-orthognathic surgery patients.

The functional state of dentofacial deformity patients before orthognathic surgery has received relatively little study. In this study, the ability to generate occlusal force was compared between 84 patients before treatment for various dentofacial deformities and 57 controls. Maximal and submaximal bite forces were measured at the incisor and right and left first molar bite positions. Electromyographic activity (EMG) was recorded bilaterally from the anterior temporalis, posterior temporalis, and masseter muscles during each bite. An efficiency ratio was calculated for the jaw muscles by dividing the level of EMG by the occlusal force. There was a reduced ability to generate occlusal forces in the patients before surgery, especially among female patients. The reductions in maximal occlusal force were correlated with reduced efficiency of the jaw muscles.

Comparison of habitual masticatory cycles and muscle activity before and after orthognathic surgery

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.