Hypomobility after maxillary and mandibular osteotomies

Effects of Chewing Exerciser on the Recovery of Masticatory Function Recovery after Orthognathic Surgery: A Single-Center Randomized Clinical Trial, a Preliminary Study

Background and Objectives: The aim of this study was to evaluate the effects of the chewing exerciser (CE) on the functional recovery of the masticatory muscles after orthognathic surgery. Material and Methods: This randomized clinical trial was conducted in patients undergoing bimaxillary orthognathic surgery including bilateral sagittal split ramus osteotomy. Postoperative physiotherapy (PT) was performed for 3 weeks starting 3 weeks after the surgery. The patients were randomly divided into two groups: control (Con) (conventional PT) group and CE group (use of CE in addition to conventional PT). The masticatory function was evaluated based on three standards: bite force (BF), amount of mouth opening (MO), and surface electromyography (sEMG) of the anterior temporal muscle (TA), masseter muscle (MM), sternocleidomastoid muscle, and anterior belly of digastric muscle before, 3 weeks (before PT) and 6 weeks after the surgery (after PT). Results: Finally, 22 subjects participated in this study: 10 patients for Con group and 12 patients for CE group. In both groups, the BF, which was reduced significantly after the surgery, recovered after the PT similar to that before the surgery. In both groups, the MO was also significantly reduced by the surgery. However, it did not recover as much, as it was before the surgery after applying the PT. There was no difference in BF and MO between the two groups. All muscles did not show significant changes in sEMG by surgery and PT at both resting and clenching states. Conclusion: Applying CE as a PT after orthognathic surgery did not cause any harmful side effects. In both groups, the weakened muscle activity after orthognathic surgery (OGS) was adequately restored 6 weeks after the surgery. However, CE did not offer a statistically significant benefit to the masticatory function in the recovery process after OGS.

Comparison of Maximum Mouth Opening Following Mandibular Bilateral Sagittal Splitting Ramus osteotomies in Class III Females Using Two Different Osteosynthesis Methods

BACKGROUND

Limitation of mouth opening is a common complaint following orthognathic surgery.

OBJECTIVES

This investigation reports on the progress of maximum incisal opening following orthognathic surgery and compares the impact of two different osteosynthesis methods on mouth opening in female patients with Class III dentofacial deformities.

METHODS

Forty cases of skeletal class III malocclusion were divided into twenty cases treated using the conventional single miniplate osteosynthesis method (P1) and twenty cases using the additional L-shaped miniplate osteosynthesis method (P2). No significant differences in pre-operative clinical status were detected between the P1 and P2 group, and all patients were managed with elastics in the post-operative period. Independent mouth opening exercises were initiated seven days after surgery, and inter-incisal distance was measured as maximum mouth opening (MMO) at 1 week, 2 weeks, and 1, 2, 3, 6 months. Statistical analysis was performed in order to analyse differences in MMO between the P1 and P2 groups (Prism 7 GraphPad software, San Diego, CA). Values of P < .05 were considered to be significant.

RESULTS

MMO significantly increased from 2 weeks after surgery in both groups. The MMO of P2 was significantly larger than that of P1 in all experimental periods after surgery. MMO was statistically improved in P2 at 2 months after surgery, while MMO in P1 was significantly smaller than the pre-operative MMO, even at 6 months post-operative. A minimum MMO of 40 mm was achieved by all patients.

CONCLUSION

L-shaped miniplate osteosynthesis was more useful for early limitation of mandibular opening improvement than conventional single miniplate osteosynthesis.

Evaluation of border movement of the mandible before and after orthognathic surgery using a kinesiograph

PURPOSE

The purpose of this study was to examine the changes in the mandibular border movement between class II and class III jaw deformity patients before and after orthognathic surgery, by using the same device.

SUBJECTS

and Methods: Eighty one patients (28 in class II and 53 in class III) who underwent sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy using absorbable plate fixation and 27 controls with normal occlusion were enrolled. Mandibular border movement (observed using a kinesiograph) was recorded with a mandibular movement measure system (K7) before surgery, and at 6 months and 1 year after surgery. Time-course changes of 5 components of the mandibular border movement (MVO: Maximum vertical opening, CO to MAP: Maximum antero-posterior movement from centric occlusion, MLDL: maximum lateral deviation left, MLDR: maximum lateral deviation right, CO to MO: centric occlusion to maximum opening) were compared between classes II, III and controls statistically. The relationship between lateral cephalometric measurements and the components of mandibular border movement was also examined.

RESULTS

There was a significant difference in CO to MAP (P = 0.0025) and CO to MO (P < 0.0001) between class II and class III in the time-course change. In class III, mean and standard deviation of MVO were 44.5 ± 6.7 mm before surgery and 39.8 ± 6.8 mm after 1 year. Mean and standard deviation of CO to MAP were 25.2 ± 6.8 mm before surgery and 21.5 ± 7.9 mm after 1 year. Mean and standard deviation of CO to MO were 53.4 ± 9.0 mm before surgery and 47.3 ± 8.4 mm after 1 year. In class II, mean and standard deviation of MVO were 38.8 ± 5.8 mm before surgery and 36.2 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MAP were 18.0 ± 6.3 mm before surgery and 17.8 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MO were 43.1 ± 7.5 mm before surgery and 39.6 ± 10.5 mm after 1 year. In MVO, CO to MAP and CO to MO, the values after 1 year did not significantly reach the pre-operative values in class III (P = 0.0001, P = 0.0007 and P < 0.0001), although there was no significant difference between pre-operation and after 1 year in class II. In CO to MO, class II (mean and standard deviation 39.6 ± 10.5 mm) and class III (mean and standard deviation 47.3 ± 8.4 mm) still remained smaller values than control (mean and standard deviation 52.7 ± 9.2 mm) after 1 year (P < 0.0001 and P = 0.0095).

CONCLUSION

This study suggests that bi-maxillary surgery can have more influence on the reduction in the range of mandibular border movement including vertical or antero-posterior motion than lateral deviation motion, in both groups. The difference in the time-course change in the mandibular border movement between the groups might depend more on the mandibular length than on the movement direction of the mandible by surgery such as advancement or setback.

Temporomandibular joint function 10-15 years after mandibular setback surgery and six weeks of intermaxillary fixation

Intermaxillary fixation (IMF) is a classic method for immobilization of the mandible after mandibular fractures and corrective surgery. However, it has been suggested that IMF may be a risk for developing temporomandibular joint (TMJ)-related symptoms, especially when applied for longer periods.

Treatment outcomes of archwise distraction osteogenesis in mandibular dentoalveolar retrognathia cases

The aim of this study was to describe the treatment of class II malocclusion by sagittal advancement of the alveolar bone in the symphyseal area using an intraoral archwise distractor device and to determine the effects of this method on the dentoalveolar complex. Fifteen patients (10 female, five male) aged 16-20 years with a class II division 2 malocclusion, characterized by mandibular dentoalveolar retrusion and a prominent chin, underwent archwise alveolar distraction in the anterior mandible. Lateral cephalometric radiographs were obtained before distraction (T0), after 6 weeks of consolidation (T1), and after debonding (T2). Linear and angular skeletal, dental, and soft tissue measurements were performed. Forty-seven parameters were measured for each of the 15 subjects on pre- and postoperative lateral cephalometric radiographs (T0, T1, and T2). The distraction protocol was successful in all patients. Skeletally, the mandible showed a clockwise rotation. B-point moved forward significantly (P<0.05). Overjet decreased significantly (P<0.001). The total profile angle was unaffected, and the improvement in the submental fold was highly significant (P<0.001). The intraoral archwise distraction force that is applied through brackets and archwires is sufficiently effective for alveolar advancement. This procedure is simple and effective in the treatment of specific adult patients with a class II division 2 malocclusion, characterized by a prominent chin and severe mandibular dentoalveolar retrusion.

The relationship between the changes in three-dimensional facial morphology and mandibular movement after orthognathic surgery

PURPOSE

The purpose of this study was to investigate the relationship between changes in three-dimensional (3D) facial morphology and mandibular movement after orthognathic surgery. We hypothesized that facial morphology changes after orthognathic surgery exert effects on 3D mandibular movement.

MATERIALS AND METHODS

We conducted a prospective follow-up study of patients who had undergone orthognathic surgical procedures. Three-dimensional facial morphological values were measured from facial CT images before and three months after orthognathic surgery. Three-dimensional maximum mandibular opening (MMO) values of four points (bilateral condylions, infradentale, and pogonion) were also measured using a mandibular movement tracking and simulation system. The predictor variables were changes in morphological parameters divided into two groups (deviated side (DS) or contralateral side (CS) groups), and the outcome variables were changes in the MMO at four points.

RESULTS

We evaluated 21 subjects who had undergone orthognathic surgical procedures. Alterations in the TFH (total facial height), LFH (lower facial height), CS MBL (mandibular body length), and DS RL (ramus length) were negatively correlated with changes in bilateral condylar movement. The UFH, DS MBL and CS ML (mandibular length) showed correlations with infradentale movement. The CS ML, DS ML, MBL, UFH, and SNB were correlated with pogonion movement.

CONCLUSION

The height of the face is most likely to affect post-operative mandibular movement, and is negatively correlated with movement changes in the condyles, infradentale and pogonion. The changes in CS morphological parameters are more correlated with mandibular movement changes than the DS. The changes in CS MBL and bilateral RL were negatively correlated with condylar movement changes, while the bilateral MBL and CS ML were positively correlated with changes in infradentale and pogonion.

Temporomandibular disorders after orthognathic surgery in patients with mandibular prognathism with depression as a risk factor

OBJECTIVE

To examine the prevalence of temporomandibular disorders (TMD) after orthodontic-surgical treatment in patients with mandibular prognathism and analyze psychosocial variables related to TMD.

MATERIALS AND METHODS

The case-control study comprised 40 patients with mandibular prognathism who underwent combined orthodontic-surgical treatment (orthognathic surgery group). Forty-two patients with untreated mandibular prognathism served as a control group. Research diagnostic criteria for temporomandibular disorders was used in order to assess the clinical diagnosis of TMD (Axis I) and to estimate depression, somatization and patient's disability related to chronic pain (Axis II).

RESULTS

The overall prevalence of TMD was not significantly different between the groups. Myofascial pain was significantly higher, while arthralgia, arthritis and arthrosis was significantly lower in the orthognathic group compared with the controls (90.5% vs 50.0%, 0.0% vs 27.8%, respectively) (p < 0.05). Females in orthognathic surgery group showed higher prevalence of TMD (p < 0.05) and myofascial pain (p < 0.01) and increased level of chronic pain (p < 0.05) in comparison with post-operative males. No significant difference in chronic pain, somatization and depression scores was found between investigated groups. With respect to presence of TMD within the groups depression was higher in untreated subjects with dysfunction (p < 0.05).

CONCLUSION

Prevalence of TMD immediately after completion of orthodontic-surgical treatment for mandibular prognathism is similar to frequency of dysfunction in untreated subjects, is significantly higher in females and is most commonly myogenic. Furthermore, females show an increased level of chronic pain post-operatively. Somatization and depression levels do not differ between patients with corrected prognathism and untreated prognathic patients.

Lip competence in Class III patients undergoing orthognathic surgery: an electromyographic study

PURPOSE

The aim of this study was to compare the presurgical and postsurgical electromyographic (EMG) activities of the lips in patients with skeletal Class III treated with combined orthognathic surgery and contrast these data with those obtained from a control group with skeletal Class I.

PATIENTS AND METHODS

Ten patients with skeletal Class III underwent the registration of EMG activity before an orthognathic surgical procedure and 4 months after surgery. The results were compared with a control group of 11 healthy patients with skeletal Class I and clinical and EMG lip competence. EMG activity was recorded from the upper orbicularis oris and mentalis muscles during swallowing, lips in contact (LC), and lips apart (LA) using bipolar surface electrodes. The competence condition was assessed by determining the difference in the EMG activity of the mentalis muscle (LC-LA ≤0 for lip competence).

RESULTS

Patients with skeletal Class III showed greater EMG activity than the control group before and after surgery. Patients with skeletal Class III showed a significantly greater difference in LC-LA than the control group before surgery for the 2 muscles (P < .05). No significant difference was found between the skeletal Class III group after surgery and the control group for the mentalis muscle (P > .05).

CONCLUSIONS

Four months after treatment with orthognathic surgery, patients with skeletal Class III and an initial muscle activity pattern of lip incompetence different from the control group (P < .05) showed EMG values compatible with lip competence. These values were similar to the control group.

Temporomandibular joint dysfunction and orthognathic surgery: a retrospective study

BACKGROUND

Relations between maxillo-mandibular deformities and TMJ disorders have been the object of different studies in medical literature and there are various opinions concerning the alteration of TMJ dysfunction after orthognathic surgery. The purpose of the present study was to evaluate TMJ disorders changes before and after orthognathic surgery, and to assess the risk of creating new TMJ symptoms on asymptomatic patients.

METHODS

A questionnaire was sent to 176 patients operated at the Maxillo-Facial Service of the Lille's 2 Universitary Hospital Center (Chairman Pr Joël Ferri) from 01.01.2006 to 01.01.2008. 57 patients (35 females and 22 males), age range from 16 to 65 years old, filled the questionnaire. The prevalence and the results on pain, sounds, clicking, joint locking, limited mouth opening, and tenseness were evaluated comparing different subgroups of patients.

RESULTS

TMJ symptoms were significantly reduced after treatment for patients with pre-operative symptoms. The overall subjective treatment outcome was: improvement for 80.0% of patients, no change for 16.4% of patients, and an increase of symptoms for 3.6% of them. Thus, most patients were very satisfied with the results. However the appearance of new onset of TMJ symptoms is common. There was no statistical difference in the prevalence of preoperative TMJ symptoms and on postoperative results in class II compared to class III patients.

CONCLUSIONS

These observations demonstrate that: there is a high prevalence of TMJ disorders in dysgnathic patients; most of patients with preoperative TMJ signs and symptoms can improve TMJ dysfunction and pain levels can be reduced by orthognathic treatment; a percentage of dysgnathic patients who were preoperatively asymptomatic can develop TMJ disorders after surgery but this risk is low.

Neurosensory and functional impairment in sagittal split osteotomies: a longitudinal and long-term follow-up study

The aim was to conduct a long-term follow-up study on the function and sensitivity of the mandible in advancement and setback patients after bilateral sagittal split osteotomy (BSSO) with rigid internal fixation. The advancement and setback groups consisted of 16 (12 females and 4 males, mean age: 21.4 and 21.3 years, respectively) and 17 (11 females and 6 males, mean age: 27.1 and 27.7 years, respectively). The final follow-up was a mean of 12.7 years (T4) post-operatively. The other follow-up examinations were before surgery (T1) and 7.3/6.6 (T2) and 13.9/14.4 (T3) months after surgery. To evaluate craniomandibular function, mouth-opening capacity, laterotrusion, protrusion, deviations during opening, pain and clicking of the temporomandibular joint (TMJ), muscular pain, and the retruded contact position-intercuspal position (RC-IP) distance were examined. A questionnaire was used to record subjective reports. The neurosensory status was determined with two-point discrimination (2-pd), the pointed, blunt, and light-touch tests. Statistical analysis included the following tests: Wilcoxon signed ranked matched pairs, Mann-Whitney U, paired t, and Fisher's exact test. Bonferroni's adjustments were made for evaluation of the questionnaire and Spearman's rank correlation coefficients to determine the interdependence of selected variables. Craniomandibular function showed restitution at T4 after 12.7 years. The 2-pd at the lip and chin had largely normalized in the two groups at T3. At T4, there was a significant increase of 2-pd at the lip and chin in both groups. The discrimination between sharp and blunt was limited in both groups in 25 per cent of patients at T4. Dysfunctions such as TMJ clicking, bruxism, and pain in the TMJ and muscles were neither increased nor decreased after BSSO. The initial post-surgical neurosensory impairment was barely detectable 1 year post-surgery. The new neurosensory impairment manifested at T4 was probably due to the normal human process of ageing. Neither age, gender, surgical advancement, nor setback showed any significant correlations.

Evaluation of condylar translation by sonography versus axiography in orthognathic surgery patients

PURPOSE

This study compares measurement of the condylar translation by sonography or axiography in preoperative assessment and follow-up of orthognathic surgery patients.

PATIENTS AND METHODS

Forty-seven moderately dysgnathic patients had consecutive examinations by axiography and sonography in a blind fashion at a single time point by 2 observers. Thirty-nine different dysgnathic patients, scheduled for isolated Le Fort I osteotomy, had preoperative condylar translation and 24-month follow-up measured randomized by either axiography (25 patients as control group) or sonography (14 patients as study group).

RESULTS

The examination time for axiography was 20 minutes average versus 2 minutes for sonography. The mean differences were 1.7 mm in opening, 2.1 mm in protrusion, and 3.3 mm for mediotrusion. Pearson's proportionality quotient was r = 0.75, analysis of variance (P <.95, F = 3.9, alpha =.05 significance level) was not significant. The 24-month longitudinal follow-up showed a Pearson's proportionality quotient of r = 0.7 between study and control group, and no significant difference in analysis of variance (P <.075, F = 2.81, alpha =.05 significance level).

CONCLUSION

Sonography proved adequate for assessment and follow-up of condylar translation compared with axiography in orthognathic surgery patients. Temporomandibular joint sonography was faster and more comfortable, allowed 1-week postoperative examination and reexaminations, and was equally exact. Anatomic details like joint degeneration and disc displacement could be assessed. However, sonography did not measure the inclination of the condylar track.

Proximal segment positioning in bilateral sagittal split osteotomy: intraoperative controlled positioning by a positioning splint

PURPOSE

Most techniques of proximal segment positioning hinder intraoperative condyle displacement. However, merely maintaining condylar position cannot optimize the preoperative condyle-disc-fossa relationship. This study attempts to optimize condylar position in the osteotomy patient.

PATIENTS AND METHODS

A study group of 23 bimaxillary operated patients had intraoperative joint positioning by positioning splint and plates (9 Angle Class II, 14 Class III). After assessing the habitual and appraising the optimized condyle position on preoperative sonograms and magnetic resonance images, positioning splints were constructed as acrylic occlusal wafers in a semi-individual articulator. Set in occlusion before adaptation of positioning plates, they were intended to move the condyles into the calculated position. Eighteen bimaxillary operated control patients had conventional plate positioning according to the habitual occlusion (9 Angle Class II, 9 Class III). Clinical follow-up, axiography, or sonography was maintained for 24 months. Preoperative lateral cephalograms were scrutinized for horizontal and vertical joint spaces and compared with the immediate postoperative radiography.

RESULTS

Postoperative Class II study group patients had less dorsal and more vertical joint space and Class III patients more dorsal and vertical space compared with the controls. The study group exhibited significantly less postoperative dysfunction compared with the control group (2-way analysis of variance: P <.021, F = 9.2, alpha =.05 significance level), disc dislocation prevalence was lower (P <.07, F = 9.2), postoperative changes in condylar translation were smaller (P <.014, F = 4.9), and 8% skeletal relapses versus 22% in the controls were seen.

CONCLUSIONS

A proximal segment-positioning splint effectively positioned the condyle in the desired direction, but with considerable relapse, significantly reduced postoperative dysfunction, disc dislocations, changes to the condylar translation, and incidence of skeletal relapse at 24-month follow-up.

Temporomandibuläre Funktionsbefunde nach Dysgnathieoperationen im Vergleich zu einer bevölkerungsrepräsentativen Studie

AIM

The temporomandibular function of patients after orthognathic surgery was evaluated with the Helkimo index (D 0-III) and compared with a normal population.

PATIENTS AND METHODS

Temporomandibular disorders (TMD) were evaluated with the Helkimo index (D 0-III) in a group of patients (n=105, F=69, M=36) after osteotomies. The average follow-up time was 47 months (9-141 months). The osteotomies performed were as follows: 58 bilateral sagittal split osteotomies, 12 Le Fort I osteotomies, 22 bimaxillary osteotomies, and 13 segment-osteotomies. A control group (n=202, F=114, M=88, age 20-39 years) was examined in an epidemiological study. The statistical analysis was performed using Windows software SPSS 10.0.

RESULT

In 82.8% of the patients no symptoms or mild dysfunction were found. The comparison between the patient group (31.4%) and the control group (31.7%) revealed a similar frequency. The most frequent dysfunction was a reduced mobility of the mandible, which determined the statistical significance (p<0,05) between the patients and the control group for the dysfunction group D II and D III. The chi-square test could not detect any difference between sex and the kind of osteotomy with regard to dysfunction.

Mandibular range of motion after bilateral sagittal split ramus osteotomy with wire osteosynthesis or rigid fixation

OBJECTIVES

An analysis was conducted to compare mandibular range of motion among Class II patients treated with wire osteosynthesis or rigid internal fixation after surgical mandibular advancement.

STUDY DESIGN

Patients randomly received wire osteosynthesis and 8 weeks of maxillomandibular fixation (n = 49) or rigid internal fixation (n = 78). Mandibular range of motion was measured 2 weeks before surgery and 8 weeks, 6 months, and 1, 2, and 5 years after surgery.

RESULTS

Both groups showed decreased mobility in all movement dimensions that progressively recovered to near presurgical levels over the 5-year follow-up period. The difference in range of motion between treatment groups was not statistically significant. Changes in proximal and distal segment position could not explain decreased mobility.

CONCLUSIONS

Similar decreases in mandibular mobility occurred with wire and rigid fixation of a bilateral sagittal split ramus osteotomy after surgery. Long-term changes were statistically, but not clinically, significant.

Orthognathic surgery: patients' subjective findings with focus on the temporomandibular joint

Two hundred and ninety-six patients who underwent various orthognathic surgery procedures were questioned, a minimum of 1 year postoperatively, on their overall subjective findings. Patient satisfaction, willingness to resubmit to surgery, self-confidence and subjective changes in their temporomandibular joints (TMJ) function and masticatory efficiency were evaluated. 87% would undergo the combined surgical-orthodontic treatment again. Self-confidence improved in 77% of the patients. There was a subjective improvement in TMJ function in 40% of the patients and a worsening in 11%; masticatory function was improved in 41% and worsened in 7% of the patients.

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.

Improvement of maximum occlusal forces after orthognathic surgery

PURPOSE

A number of studies have reported that maximum voluntary bite forces increase after orthognathic surgery. This study determined rates of long-term improvement in bite forces and looked for both sex-related differences in improvement and for any differences among surgical procedures.

PATIENTS AND METHODS

The study tested 117 patients before surgery and between 6 months and 3 years after surgery. At each trial, unilateral maximum voluntary bite force was measured at four different tooth positions using a standard transducer. Forty-three control subjects were similarly tested. The rate of increase in maximum bite force was calculated separately for male and female patients in various groups of patients and the controls.

RESULTS

The patients had significantly lower maximum bite forces than the controls before surgery and for as long as 2 years after surgery. Within 6 months after surgery, patients' bite forces were already greater than their pre-surgical forces. Patients generally showed steady improvement in bite force thereafter, with male patients improving more quickly than female patients. There were no clear differences among surgical procedures.

CONCLUSIONS

Any temporary reduction in maximum voluntary bite force disappears less than 6 months after orthognathic surgery. Orthognathic surgery improves patients' bite forces, but this improvement may be gradual, requiring many months.

Long-term effects of orthognathic surgery on the temporomandibular joint: comparison of rigid and nonrigid fixation methods

Sixty-six patients were examined between 2 and 9.5 years after bilateral sagittal split mandibular ramus osteotomy. Thirty-two patients had nonrigid fixation consisting of superior border wires and intermaxillary fixation, while 34 patients had rigid plate fixation of the osteotomy sites with immediate function. There were no demonstrable long-term differences between the two groups with respect to mandibular vertical opening, crepitance, and temporomandibular joint pain. Masticatory muscle pain and temporomandibular joint clicking improved with rigid fixation and worsened with nonrigid fixation.

Functional characteristics of retrognathic patients before and after mandibular advancement surgery

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.

A longitudinal study of changes in masticatory performance of patients undergoing orthognathic surgery

PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

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).

CONCLUSION

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.

The effects of orthodontic treatment on isometric bite forces and mandibular motion in patients before orthognathic surgery

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.

Alteration of temporomandibular joint symptoms after orthognathic surgery: comparison with healthy volunteers

PURPOSE

The purpose was to investigate alterations in temporomandibular joint (TMJ) dysfunction after orthognathic surgery.

PATIENTS AND METHODS

TMJ symptoms of preoperative patients (n = 30) were compared with those of healthy volunteers (n = 30), and changes in the symptoms were evaluated at 3- and 6-month postoperative intervals.

RESULTS

There was no significant difference in the incidence of TMJ sounds, deviation of mouth opening, and tenderness of TMJ and masticatory muscles between patients and volunteers. Patients did not report TMJ symptoms significantly more often than the control subjects. At both 3 and 6 months after surgery, half or more of the patients showed no change in TMJ sounds, deviation of mouth opening, or tenderness of TMJ and masticatory muscles. At each evaluation, some patients exhibited improvement of TMJ symptoms or showed changes for the worse. Findings of TMJ sounds were observed to be associated with the postoperative reduction of mandibular mobility.

CONCLUSION

These results suggest that alterations of TMJ symptoms after orthognathic surgery do not always result from the correction of malocclusion.

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 person's ability to chew food might include occlusal relationships and mechanical advantage.

TMJ performance and behaviour in patients more than 6 years after Le Fort I osteotomy

Sixteen non cleft patients treated by one piece Le Fort I osteotomy were investigated for TMJ symptoms. Clinical examination and subjective assessment by the patients was used over a 6-year period. No increase in symptoms was recorded in the osteotomy group as compared to the general population, however, condylar atrophy was seen in two patients. Both of these patients were classified as high mandibular plane angle, with absolute mandibular retrognathism. This suggests that this group may be at greater risk of condylar atrophy.

[Temporomandibular joint function after orthognathic surgery--the individual factors]

Case studies presented in the literature present evidence that individual factors may influence mandibular mobility unfavorably after mandibular advancement osteotomies. These factors are, respectively: high preoperative dysfunction index, preoperative articular pain in movement, preoperative reciprocal clicking, advanced patient age, and significant overjet reduction. This study identifies these individual factors, which can influence postoperative functional condition, and documents conclusively the importance of individual, function oriented preoperative planning in orthognathic surgery. Taken together these factors indicate that the adaptation ability of the effected tissue should be given greater attention in planning the operation.

[Longitudinal changes in the acoustic temporomandibular symptoms due to different procedures of orthognathic surgery]

A longitudinal study of TMJ sounds prior to and after combined orthodontic-orthognathic surgical procedures was carried out. The relative frequency of such sounds two days prior to operation (T0) and three months (T1), eight months (T2), 14.5 months (T3), and 25.5 months (T4) postoperatively remained--treatment-independently--largely unchanged. Chances in frequency between T0 and T4 showed only a nonsignificant tendency to differ in comparison with changes seen after orthodontic treatment (A) only. An analysis of individual changes revealed that after Le Fort I osteotomy (B) and bimaxillary procedures/posterior mandibular repositioning (D), no change in the preoperative sounds is to be expected. In contrast, following mandibular advancement (C) TMJ sounds first disappeared, in particular in the period immediately following operation (T0-T1), but also subsequently reappeared. The difference vis-a-vis group B (Le Fort I osteotomies) was statistically significant (group B vs. group C: p less than or equal to 0.01.

Histologic examination of the temporomandibular joint after mandibular advancement with and without rigid fixation: an experimental investigation in adult Macaca mulatta

This study evaluated the histologic response of the temporomandibular joint (TMJ) following mandibular advancement using rigid and nonrigid fixation in monkeys. Twelve adult female rhesus monkeys underwent sagittal ramus osteotomies with advancement. Six of them were placed into maxillomandibular fixation (MMF); six underwent bicortical bone-screw fixation without MMF. Changes in condylar position were quantified using lateral cephalograms with the aid of bone markers. The animals were killed at 6 weeks and the TMJs were prepared for histologic analysis. Three measures of condylar cartilage thickness were obtained for each animal and were correlated to changes in position of the condyle. Animals who underwent MMF showed a tendency for anterior movement of the condyles; animals who underwent rigid fixation showed a tendency for posterior condylar position. Thicker cartilage layers were found in the MMF animals. Animals who had posterior displacement of the condyles showed evidence of resorption of the posterior surface of the condyle and anterior surface of the postglenoid spine. There was a significant correlation between a change in the horizontal position of the condyle and the thickness of the posterior aspect of the condylar cartilage. The results of this study indicate that alterations in condylar position may induce remodeling changes within the TMJ.

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)

[The subjective and objective assessment of the functional treatment results after combined orthodontic and oral surgical measures]

The status of temporomandibular joint and muscle function was examined in a group of 22 adult patients, who underwent combined orthodontic and surgical treatment. Even though nearly all patients were very content with the results of the therapy, 2/3 showed a rather reduced movement of the condyle after mandibular sagittal split osteotomy. The causing factors are: arthrosis, permanent displacement of the disc or a change of muscle function after surgery.

[Changes in opening mobility due to surgical advancement of the mandible]

A prospective follow-up study of 21 class-II patients, who were treated with a combination of orthodontics and orthognathic surgery, revealed typical postoperative changes in opening mobility. Their characteristics were: a strong initial loss of mobility and a regeneration period of about one year. Because the increase of mobility could not completely compensate for the initial reduction, a significantly reduced mobility was detected 25.5 months postoperatively. This reduction was considered as clinically acceptable, since former studies showed more unfavorable developments. However, individual changes of mobility are worth of notice. The comparison of condylar-related axiographic measurements with incisal measurements showed that the reduction of the length of axiographic tracings was more prominent than the "clinical-effective" reduction of the combined condylar rotation and translation.

A comparative study of temporomandibular symptoms following mandibular advancement by bilateral sagittal split osteotomies: rigid versus nonrigid fixation

Rigid fixation to attach proximal and distal segments during bony healing of osteotomy sites has become increasingly popular. The effects of rigid fixation on the temporomandibular joints have been questioned. The purpose of this study was to evaluate the effects of rigid fixation after bilateral sagittal split osteotomies on temporomandibular dysfunction symptoms. Forty patients who had mandibular advancement surgery were evaluated for temporomandibular joint dysfunction. Twenty had received rigid fixation, and twenty had received nonrigid fixation. It was determined that there was no statistically significant difference in temporomandibular signs or symptoms between patients who were treated with rigid internal fixation for bilateral sagittal split osteotomies for mandibular advancement and those patients who were treated with nonrigid wire fixation.

Analysis of temporomandibular joint function after orthognathic surgery using condylar path tracings

Condylar path tracings provide quantitative and qualitative data regarding the functional status of the temporomandibular joint. This study was designed to identify the functional status of the TMJ by means of condylar path tracings before treatment and to monitor the response of the TMJ to orthognathic surgery. Baseline data for condylar tracings using a sagittal recording device were established in relation to normal limits for opening, protrusive, and medial excursions of the mandible. In 54 patients 108 joints were studied before and up to 1 year after orthognathic surgery. Internal derangements were identified with condylar tracings before treatment in 72% of all joints studied. Also, condylar tracings identified internal derangements that were not found on clinical examination in 11 of 39 patients. Functional adaptation of the TMJ was found to be more favorable for mandibular reduction and maxillary impaction than for mandibular advancement or combined upper and lower jaw procedures. Condylar path tracings were shown to represent a noninvasive technique to identify and monitor the functional status of the TMJ in response to surgical orthodontics.

Arthroscopic surgery for treatment of temporomandibular joint hypomobility after mandibular sagittal osteotomy

Arthroscopic surgery is an effective method for treating painful hypomobility of the temporomandibular joint. Decreased range of motion after sagittal ramus osteotomies of the mandible has been reported. Causes may include intra-articular factors. These cases may be effectively treated with arthroscopic lysis and lavage after failure of nonsurgical modalities. A series of 15 patients is presented.