Functional characteristics of patients with anterior open bite before and after surgical correction

The purposes of this investigation were to compare functional performance between controls and a sample of patients with skeletal anterior open bite prior to surgical correction and to examine how the patients' oral motor function adapted after treatment. Five female patients with skeletal open bite malocclusion were treated with Le Fort I osteotomy and compared to sex-, size-, and age-matched controls. Measurements of skeletal morphology, mandibular range of motion, occlusal force, and muscle efficiency were taken on all subjects over time. Prior to surgery, all patients had lower occlusal forces than did controls at all bite positions. After surgery, occlusal forces at several occlusal positions increased significantly from the presurgical recordings but remained below the level of controls. The mechanical advantages of the muscles of mastication were not significantly different between controls and patients either before or after surgery. The results of this study suggest that correction of skeletal open bite malocclusion may improve occlusal force, but a larger sample is needed to confirm this finding.

Primary cultures of human hepatocytes but not HepG2 hepatoblastoma cells are suitable for the study of glycosidic conjugation of bile acids

To define the role of glycosidic conjugation of bile acids in humans, an in vitro model system is desirable. We studied the formation of glycosidic conjugates of bile acids in primary cultures of human hepatocytes, isolated from organ donor liver, and the human hepatoblastoma cell line, HepG2. Cells were incubated with 100 microM bile acids (chenodeoxycholic, CDCA; hyodeoxycholic, HDCA; and isoursodeoxycholic acids, isoUDCA) and 1-2 mM uridine diphosphoglycosides (UDP-glucose, UDP-Glc; UDP-glucuronic acid, UDP-GlcA, and UDP-N-acetylglucosamine, UDP-GlcNAc), and octyl glucoside. Media were analysed by electrospray-/gas chromatography-mass spectrometry and electrospray with collision induced dissociation. Primary cultures of human hepatocytes formed glycosidic bile acid conjugates with UDP-sugars (6alpha-Glc-HDCA, 6alpha-GlcA-HDCA, and 7beta-GlcNAc-isoUDCA) and octyl glucoside as sugar donors (3alpha-Glc-CDCA). HDCA was completely metabolised to either Glc-HDCA, a compound yet not found in vivo, or GlcA-HDCA. No glycosidic bile acid conjugate was found in media from experiments with HepG2. Thus, primary cultures of human hepatocytes, but not HepG2, are suitable in vitro systems for the study of glycosidic bile acid conjugation reactions.

Portrait of the physiotherapy profession

As a profession integral to health promotion, prevention, acute care and rehabilitation physiotherapy plays an essential role in the health care system. This paper explores the nature of physiotherapy, the role of physiotherapy in health care, the practice of physiotherapy internationally, the education of physiotherapists, the regulation of physiotherapy practice and the maintenance of practice standards.

Clinical implications of sex in acute temporomandibular disorders

BACKGROUND

Previous research on temporomandibular disorders, or TMDs, has been somewhat limited, with studies having low numbers of subjects, restricting the focus to women or looking at patients already diagnosed with chronic TMD. Because early intervention is beneficial, it is important to understand the symptoms that men and women have in the acute stage of TMD.

METHODS

A total of 233 patients (161 women, 72 men) with acute TMD symptoms were assessed with a battery of biopsychosocial measures. Patients were diagnosed as having TMD on the basis of research diagnostic criteria, or RDC, or RDC, for TMD. After six months, patients were reassessed to determine whether they continued to have pain, thus classifying them as having chronic TMD. The authors found that 153 patients (47 men, 106 women) had developed a chronic condition, while 80 patients (25 men, 55 women) no longer reported pain (nonchronic).

RESULTS

Female and male patients who developed chronic TMD differed significantly from patients who had acute symptoms that subsided. Women who developed chronic TMD exhibited significantly more psychosocial distress and impairment than women who did not develop chronic TMD, in terms of Diagnostic and Statistical Manual, Fourth Edition, or DSM-IV, diagnoses; Beck Depression Inventory, or BDI, scores; Minnesota Multiphasic Personality Inventory scores; Multidimensional Pain Inventory, or MPI, scores; and physical and psychological measures assessed with the RDC for TMD. Men who developed chronic TMD differed significantly from men who did not develop chronic TMD, in that they exhibited more impairment in terms of DSM-IV diagnoses and BDI and RDC measures.

CONCLUSIONS

These findings provide evidence that significant differences exist between men and women in regard to acute TMD symptoms.

CLINICAL IMPLICATIONS

The biopsychosocial differences between men and women suggest that some treatments may be more beneficial for women than for men.

Recovery of mandibular motion after closed and open treatment of unilateral mandibular condylar process fractures

The purpose of this study was to determine the rate of recovery of mandibular motion in patients treated for fractures of the mandibular condylar process. One hundred and thirty-six patients (111 men, 25 women), 74 treated by closed and 62 by open methods, were included. They underwent testing of mandibular and condyle mobility at 6 weeks, 6 months, and 1, 2, and 3 years post surgery. Their ranges of motion were compared to those of 52 controls (26 men and 26 women). A jaw-tracking device was used to assess mandibular motion. Multilevel statistical models were used to assess differences between groups, and to estimate rate of recovery in the fracture patients. In general, patients with unilateral fractures of the condylar process had maximum excursions that returned to normal values within 3 years after fracture, regardless of treatment. Patients treated open exhibited a faster rate of improvement in maximum interincisal opening than patients treated closed (0.43 mm/month vs 0.15 mm/month, respectively), but part of the difference was due to a significantly smaller opening after 6 weeks for the patients treated open (38 mm vs 42 mm, respectively). Patients treated open also exhibited a faster rate of improvement in maximum excursion toward the fracture side than patients treated closed (0.10 mm/month vs 0.04 mm/month, respectively). Based upon this study, patients with unilateral fractures of the condylar process, who are treated closed and not put into maxillomandibular fixation but are instructed in physical therapy, can be expected to achieve normal maximum excursions within 3 years after treatment. Patients treated open will have reduced maximum opening initially, but may reach normal levels of opening sooner than patients treated without surgery. Patients treated without surgery may have smaller than normal excursion toward the non-fracture side for at least 3 years after fracture, especially if their fracture was at or above the condylar neck. Improvement rates for other maximum excursions are similar for patients treated with or without surgery.

A comparison of performance on the OMSITE and ABOMS written qualifying examination. Oral and Maxillofacial Surgery In-Training Examination. American Board of Oral and Maxillofacial Surgery

PURPOSE

The purpose of this study was to see whether there was a correlation between the performance of persons on the Oral and Maxillofacial Surgery In-Training Examination (OMSITE) and their performance on the American Board of Oral and Maxillofacial Surgery Written Qualifying Examination (ABOMS WQE).

METHODS

All OMSITE scores for residents in their last years of training during the years 1992 to 1998 and their scores on the ABOMS WQE were tabulated by American College Testing (ACT) (Iowa City, IA) and submitted for analysis. The data were analyzed using Pearson's correlation coefficients to determine any relationship between the 2 scores. Likelihood ratios were calculated to show the probability of candidates passing the ABOMS WQE based on their OMSITE score.

RESULTS

There were 765 scores provided by ACT for the years 1992 to 1998. A significantly positive correlation existed between the OMSITE and ABOMS WQE raw scores for those taking the ABOMS WQE for the first and second times, but not for subsequent attempts. Persons who scored a raw score of over 211 on the OMSITE all passed the ABOMS WQE on their first attempt. Those with a raw score of less than 134 on their OMSITE all failed the ABOMS WQE on their first attempt.

CONCLUSION

A highly positive correlation exists between candidate performance on the OMSITE and the ABOMS WQE.

Surgical complications with open treatment of mandibular condylar process fractures

PURPOSE

This study assessed the surgical complications after open treatment for fractures of the mandibular condylar process.

PATIENTS AND METHODS

A total of 178 patients with unilateral fractures of the mandibular condylar process, 85 treated closed and 93 treated open, were included in this study. A tabulation of surgical findings and intraoperative and postoperative complications was prospectively performed. Standardized animating facial photographs were obtained at several postsurgical intervals and were examined and scored by a prosthodontist and an orthodontist for signs of facial nerve palsy and the quality of the surgical scar. Standard statistical methods were used to assess differences between open and closed treatment groups.

RESULTS

There were very few intraoperative or postoperative complications. At the 6-week point, 17.2% of patients treated open had some weakness of their facial nerve. This had resolved by 6 months. The scars were judged either wide or hypertrophic in 7.5% of cases.

CONCLUSIONS

Based on this study, surgical complications of open treatment of condylar process fractures that lead to permanent dysfunction or deformity are uncommon.

Assessment of patients with facial fractures

One of the most demanding aspects of emergency medicine is the management of patients who have suffered facial trauma. The diagnosis and initial management of patients who have sustained traumatic facial injuries are discussed. The fundamentals required to assess patients with fractures of the facial skeleton and to make appropriate referrals are provided.

Facial symmetry after closed and open treatment of fractures of the mandibular condylar process

PURPOSE

This study compares vertical measures of mandibular and facial morphology after open or closed treatment for fractures of the mandibular condylar process.

PATIENTS AND METHODS

One hundred forty-six patients (121 male, 25 female), 81 treated by closed and 65 by open methods, were included in this study. Towne's and panoramic radiographs, taken at several intervals, were used to quantify the displacement of the condylar process fractures. Posteroanterior cephalograms taken at 6 weeks, 6 months, 1 year, and 2 to 3 years after treatment were used to assess posterior facial height and bigonial and occlusal plane angles. Additionally, panoramic radiographs were used to assess ramus height at the same periods. Standard statistical methods were used to assess differences between groups.

RESULTS

Patients whose condylar process fractures were treated by closed methods had significantly shorter posterior facial and ramus heights on the side of injury, and more tilting of the occlusal and bigonial planes toward the fractured side, than patients whose fractures were treated by open methods. Most of the asymmetry in patients treated by closed methods was present by 6 weeks after injury.

CONCLUSIONS

Patients treated by closed methods develop asymmetries characterized by shortening of the face on the side of injury. It is likely that loss of posterior facial height on the side of fracture in these patients is an adaptation that helps reestablish a new temporomandibular articulation.

Bile acid synthesis in cultured human hepatocytes: support for an alternative biosynthetic pathway to cholic acid

The biosynthesis of bile acids by primary cultures of normal human hepatocytes has been investigated. A general and sensitive method for the isolation and analysis of sterols and bile acids was used, based on anion exchange chromatography and gas chromatography-mass spectrometry (GC/MS). Following incubation for 5 days, 8 oxysterols and 8 C(27)- or C(24)-bile acids were identified in media and cells. Cholic and chenodeoxycholic acids conjugated with glycine or taurine were by far the major steroids found, accounting for 70% and 24% of the total, respectively, being consistent with bile acid synthesis in human liver. Small amounts of sulfated 3beta-hydroxy-5-cholenoic acid and 3beta,7alpha-dihydroxy-5beta-cholanoic acid were also detected. Nine steroids were potential bile acid precursors (2% of total), the major precursors being 7alpha, 12alpha-dihydroxy-3-oxo-4-cholenoic acid and its 5beta-reduced form. These 2 and 5 other intermediates formed a complete metabolic sequence from cholesterol to cholic acid (CA). This starts with 7alpha-hydroxylation of cholesterol, followed by oxidation to 7alpha-hydroxy-4-cholesten-3-one and 12alpha-hydroxylation. Notably, 27-hydroxylation of the product 7alpha, 12alpha-dihydroxy-4-cholesten-3-one and further oxidation and cleavage of the side chain precede A-ring reduction. A-Ring reduction may also occur before side-chain cleavage, but after 27-hydroxylation, yielding 3alpha,7alpha, 12alpha-trihydroxy-5beta-cholestanoic acid as an intermediate. The amounts of the intermediates increased in parallel to those of CA during 4 days of incubation. Suppressing 27-hydroxylation with cyclosporin A (CsA) resulted in a 10-fold accumulation of 7alpha, 12alpha-dihydroxy-4-cholesten-3-one and a decrease of the production of CA and its acidic precursors. These results suggest that the observed intermediates reflect an alternative biosynthetic pathway to CA, which may be quantitatively significant in the cells.

Morphologic and biomechanical correlates with maximum bite forces in orthognathic surgery patients

PURPOSE

The purpose of this study was to determine which factors of craniofacial morphology best predict maximum bite forces and jaw muscle strength (based on [electromyogram] EMG/force slopes) in patients selected for various orthognathic surgical procedures. These factors were then compared for their ability to separate orthognathic surgery patients by their clinical diagnosis.

PATIENTS AND METHODS

Standard lateral cephalograms were taken of 121 orthognathic surgery patients (before treatment) and 80 control subjects to establish multivariate sagittal and biomechanical factors of craniofacial form. Maximum and submaximal bite forces were recorded at 8 tooth positions for each subject. EMG activity was recorded for 3 pairs of muscles (anterior temporalis, posterior temporalis, and superficial masseter) during the isometric bites. The EMG and bite force measurements were used to calculate EMG/force slopes as a measure of jaw muscle strength. The study looked for significant correlations between the morphologic factors and maximum bite force or jaw muscle strength.

RESULTS

Factor analysis determined 12 sagittal and 6 biomechanical factors. However, only 3 of the sagittal and 4 of the biomechanical factors were significantly correlated with maximum bite force or jaw muscle strength. Factors reflecting jaw size were correlated with maximum bite forces and jaw muscle strength but generally did not separate patient groups. The factor most strongly correlated with maximum bite forces separated patients by their relative difference between anterior and posterior facial height. The factor for anteroposterior maxillomandibular discrepancies was not correlated with maximum bite force or jaw muscle strength.

CONCLUSIONS

Many cephalometric measurements used to diagnose craniofacial deformities and to assign patients to particular orthognathic surgical procedures are not correlated with maximum bite forces or jaw muscle strength. Only measurements reflecting relative differences between anterior and posterior facial height are both strongly correlated with maximum bite force and reflect assignment of surgical procedures.

Occlusal results after open or closed treatment of fractures of the mandibular condylar process

PURPOSE

This study compared the occlusal relationships after open or closed treatment for fractures of the mandibular condylar process.

PATIENTS AND METHODS

A total of 137 patients with unilateral fractures of the mandibular condylar process (neck or subcondylar), 77 treated closed and 65 treated open, were included in this study. Standardized occlusal photographs obtained at several postsurgical time intervals were examined and scored by a surgeon and an orthodontist. Standard statistical methods were used to assess differences between groups.

RESULTS

Patients treated by closed techniques had a significantly greater percentage of malocclusion compared with patients treated by open reduction, in spite of the fact that the initial displacement of the fractures was greater in patients treated by open reduction.

CONCLUSIONS

Based on this study, more consistent occlusal results can be expected when fractures of the mandibular condylar process are treated by open reduction.

A double-blind placebo-controlled study of botulinum toxin in upper limb spasticity after stroke or head injury

OBJECTIVE

To assess dose-response relationships to a single dose of botulinum toxin 'A' in upper limb spasticity associated with stroke or head injury.

DESIGN

A double-blind placebo-controlled randomized dose ranging study.

SETTING

A regional centre for neuroscience and a neurorehabilitation outpatient clinic.

SUBJECTS

Twenty-one hemiplegic patients with troublesome upper limb spasticity. Nineteen with stroke and two with head injury.

MAIN OUTCOME MEASURES

Spasticity (modified Ashworth), range of movement, posture (postural alignment and finger curl), disability (upper body dressing time and Frenchay Arm Test), patient-reported global assessment scale.

RESULTS

Combining data from all doses of botulinum toxin there was a significant reduction in spasticity at the wrist and fingers associated with a greater range of passive movement at the wrist and less finger curl at rest. There was a tendency for a further reduction in spasticity at elbow and wrist to occur with increasing dose but not for finger spasticity or curl. Effects present at six weeks were lost by 12 weeks except for a small improvement in elbow range of movement at the 1,500 Mu dose. There was no change in upper limb disability but a significant increase in patients' global assessment of benefit.

CONCLUSION

Botulinum toxin produced beneficial effects in spasticity and passive range of movement in the hemiplegic upper limb. Increasing the dose increased the magnitude of response for impairments in some muscle groups but had little effect on duration of response.

Open treatment of condylar process fractures: assessment of adequacy of repositioning and maintenance of stability

PURPOSE

This study was designed to determine how well fractured condylar processes were reduced and the stability of the internal fixation in a group of patients whose fractures were treated by open reduction.

PATIENTS AND METHODS

Sixty-one patients treated by open reduction and internal fixation for unilateral condylar process fractures were studied prospectively using Towne's and panoramic radiographs. The radiographs were made before surgery, and immediately, 6 weeks, and 6 months postoperatively. The images were traced and digitized, and the position of the fractured condylar process was statistically compared with the position of the nonfractured condylar process in both the coronal and sagittal planes. Additionally, 2 observers examined the images and assessed these same 2 factors.

RESULTS

After surgery, the difference in position between the fractured and nonfractured sides averaged less than 2 degrees (not significantly different), indicating good reduction of the fractures. However, subsequently, between 10% and 20% of condylar processes had postsurgical changes in position of more than 10 degrees.

CONCLUSIONS

This study showed that it is possible to anatomically reduce the fractured condylar process, but changes in position of the condylar fragment may then result from a loss of fixation.

Further displacement of condylar process fractures after closed treatment

PURPOSE

This study examined the changes in the position of the fractured condylar process immediately before and immediately after application of arch bars and at 6 weeks after surgery in a group of patients who underwent closed treatment.

PATIENTS AND METHODS

Sixty-five patients over the age of 16 years underwent closed treatment of unilateral mandibular condylar process fractures. Coronal and sagittal displacement of the condylar process was examined using Towne's and panoramic radiographs before treatment, immediately after placement of arch bars, and at 6 weeks. The change in position of the condylar process from one time to the next was analyzed statistically.

RESULTS

There was a statistically significant difference (mean, -5.5 degrees) in the coronal position of the condylar processes from immediately after injury to immediately after placement of arch bars. There was great variability, with some segments becoming more medially displaced and some more laterally displaced. In contrast, mean change in the sagittal position of the condylar process was not statistically significant, although some became more anteriorly and others became more posteriorly displaced. Similarly, from immediately after placement of arch bars to 6 weeks, there was great variability in position of the condylar process, but the overall change was not statistically significant.

CONCLUSIONS

The results of this study showed that position of the condylar process is not static in patients treated for condylar process fractures by closed means. These results suggest that care must be taken in basing treatment decisions on the degree of displacement or dislocation of the condylar process in presurgical radiographs.

A model for predicting chronic TMD: practical application in clinical settings

BACKGROUND

Substantial cost is associated with the treatment of chronic temporomandibular disorders, or TMDs, and patients with TMDs often experience significant psychosocial distress. Early intervention based on identified risk factors has potential financial and functional benefits.

METHODS

Two hundred four patients with acute TMD were evaluated via an assessment battery that included physical, psychological and social measures. All participants were diagnosed as having TMD on the basis of the research diagnostic criteria for TMD, Axis I. At the six-month follow-up assessment, patients were considered to have chronic TMD if they continued to have TMD pain. This resulted in 144 of the patients being classified in the chronic group and 60 being classified in the nonchronic group.

RESULTS

A comparison of the acute TMD data demonstrated that the group that went on to develop chronic TMD and the group that did not differed significantly in their scores on numerous biopsychosocial indexes. Although several biopsychosocial measures were found to differentiate these two groups before the onset of chronic TMD, logistic regression analysis demonstrated that a two-variable predictive model consisting of the presence of a muscle disorder and characteristic pain intensity (that is, the mean of these three ratings: patient's report of current pain, worst pain in the last three months and mean pain in the last three months) accurately classified 91 percent of the subjects who went on to develop chronic TMD.

CONCLUSIONS

During the acute phase of TMD, two variables allowed for an accurate prediction rate of 91 percent among patients who went on to develop chronic TMD.

CLINICAL IMPLICATIONS

This model provides clinicians with the opportunity to identify at-risk patients early and initiate adjunctive or alternative treatments, thus reducing the likelihood of the development of TMD chronicity.

Morphologic and biomechanical determinants in the selection of orthognathic surgery procedures

PURPOSE

This study examined which features of craniofacial morphology are most important in the selection of an orthognathic surgery procedure by 1) producing a small number of composite variables representing multiple measures of craniofacial morphology and craniofacial biomechanics, and 2) looking for correlations between these composite variables and selected orthognathic surgery procedures.

PATIENTS AND METHODS

Lateral cephalograms of 201 adult subjects (71 men and 130 women) were used to generate 47 standard cephalometric measures and 30 biomechanical measures. Of the 201 subjects, 121 were scheduled for orthognathic surgery to treat a variety of dentofacial deformities. Factor analysis reduced the number of variables by identifying underlying latent composite variables, thereby strengthening correlations among the reduced number. Weightings for each factor were than compared among the orthognathic surgery procedures, indicating which factors may have influenced the selection of that procedure.

RESULTS

Factor analysis determined 12 factors (explaining 93% of the variance) for the morphologic measurements and 6 factors (explaining 90% of the variance) for the biomechanical measurements. However, only 6 of the morphology factors (accounting for 53% of the morphologic variance) and 5 of the biomechanics factors (accounting for 69% of the biomechanics variance) significantly separated any of the 10 treatment groups. The separating morphology factors were generally related to relative maxillary and mandibular position or dental relationships. Of these, relative maxilla/mandible anteroposterior position was most important for defining the surgery groups. The biomechanics of the lateral pterygoid muscles did not contribute to separation of the groups.

CONCLUSIONS

Only a subset of available morphologic information was used to select surgical treatment. The most important factors in treatment selection were difference in maxillary and mandibular lengths and differences in anterior and posterior facial height. Standard morphology factors accounting for 40% of the total morphologic variance apparently played no role in selection of treatment. Several biomechanical factors differentiated treatment groups as well as or better than some standard morphology factors.

Treatment methods for fractures of the mandibular angle

Fractures of the mandibular angle are plagued with the highest rate of complication of all mandibular fractures. Over the past 10 years, various forms of treatment for these fractures were performed on an indigent inner city population. Treatment included: 1) closed reduction or intraoral open reduction and non-rigid fixation; 2) extraoral open reduction and internal fixation with an AO/ASIF reconstruction bone plate; 3) intraoral open reduction and internal fixation using a solitary lag screw; 4) intraoral open reduction and internal fixation using two 2.0 mm mini-dynamic compression plates; 5) intraoral open reduction and internal fixation using two 2.4 mm mandibular dynamic compression plates; 6) intraoral open reduction and internal fixation using two non-compression miniplates; 7) intraoral open reduction and internal fixation using a single non-compression miniplate; and 8) intraoral open reduction and internal fixation using a single malleable non-compression miniplate. This paper reviews the results of those modes of treatment when used for the same patient population at one hospital. Results of treatment show that, in this patient population, the use of either an extraoral open reduction and internal fixation with the AO/ASIF reconstruction plate or intraoral open reduction and internal fixation, using a single miniplate, are associated with the fewest complications.

Mandibular motion after closed and open treatment of unilateral mandibular condylar process fractures

PURPOSE

This study compared mandibular and condylar mobility after open or closed treatment for fractures of the mandibular condylar process.

PATIENTS AND METHODS

One hundred thirty-six patients (111 male, 25 female), 74 treated by closed and 62 by open methods, were included in this study. They underwent testing of mandibular and condyle mobility at 6 weeks, 6 months, and 1, 2, and 3 years postsurgery. A jaw-tracking device was used to assess mandibular motion. Radiographs that were traced and digitized were used to assess condylar displacement and condylar mobility. Standard statistical methods were used to assess differences between groups.

RESULTS

Patients treated by open reduction had significantly greater initial displacement of their condylar processes than did the group treated closed. Immediately after treatment and uprighting of the condyles in the open treatment group, patients treated closed had significantly more displacement. At 6 weeks, patients treated closed had some measures of mandibular mobility that were significantly greater than those in patients treated by open reduction. However, after the 6-week period there were minimal differences in mandibular mobility between groups. At 6 weeks, patients treated by open reduction had significantly greater vertical mobility of the condyle than patients treated closed despite less mouth opening. After the 6-week period, patients treated by open reduction continued to have greater condylar mobility on the fractured side than did patients treated by closed methods. No measures of postsurgical displacement correlated with mobility measures in patients treated by open reduction. However, several measures of mandibular displacement correlated with measures of mobility in patients treated closed, indicating that the more displaced the condylar process, the more limited the mobility of the mandible.

CONCLUSIONS

Based on this study, patients treated for fractures of the mandibular condylar process by open reduction had somewhat greater condylar mobility than patients treated closed, even though the former group had more severely displaced fractures before surgery. Therefore, open reduction may produce functional benefits to patients with severely displaced condylar process fractures.

Changes in masticatory patterns after bilateral fracture of the mandibular condylar process

PURPOSE

Because the morphology of the temporomandibular joint is thought to control movements of the mandible during mastication, bilateral fractures of the condylar process should disrupt masticatory patterns. The purposes of this study were 1) to document changes in masticatory patterns after such fractures, and 2) to determine whether and when normal masticatory patterns are recovered.

PATIENTS AND METHODS

Twenty-two patients (15 men and 7 women) were examined at 6 weeks, 6 months, 1 year, 2 years, and 3 years after bilateral condylar process fractures. Patients were age and sex matched to a control sample. Incisor movements in three dimensions, along with muscle activity from the anterior temporalis, posterior temporalis, and superficial masseter, were recorded at 500 Hz during mastication of a gummy candy.

RESULTS

Although the patients showed no reduction of interincisal opening during mastication, the opening was achieved with reduction of anterior translation of the condyles. Patients had significantly narrower chewing cycles, with significantly lower adductor muscular effort during the closing phases of mastication. Differences from controls were no longer detectable 1 year after the fractures.

CONCLUSION

The amount of opening during mastication may appear clinically normal in patients with bilateral condylar process fractures. However, disruption of controlling structures and lateral pterygoid function appears to reduce the amount of anterior translation and lateral excursion during the chewing cycle. Reduced adductor muscle activity during the closing phases may reduce loads on the fractured condylar processes. In general, these patients recover normal masticatory cycles within 1 year.

The relationship between submaximal activity of the lumbar extensor muscles and lumbar posteroanterior stiffness

BACKGROUND AND PURPOSE

Some patients with low back pain are thought to have increased lumbar posteroanterior (PA) stiffness. Increased activity of the lumbar extensors could contribute to this stiffness. This activity may be seen when a PA force is applied and is thought to represent much less force than occurs with a maximal voluntary contraction (MVC). Although MVCs of the lumbar extensors are known to increase lumbar PA stiffness, the effect of small amounts of voluntary contraction is not known. In this study, the effect of varying amounts of voluntary isometric muscle activity of the lumbar extensors on lumbar PA stiffness was examined.

SUBJECTS

Twenty subjects without low back pain, aged 26 to 45 years (X=34, SD=5.6), participated in the study.

METHODS

Subjects were asked to perform an isometric MVC of their lumbar extensor muscles with their pelvis fixed by exerting a force against a steel plate located over their T4 spinous process. They were then asked to perform contractions generating force equivalent to 0%, 10%, 30%, 50%, and 100% of that obtained with an MVC. Posteroanterior stiffness at L4 was measured during these contractions.

RESULTS

A Friedman one-way analysis of variance for repeated measures demonstrated a difference in PA stiffness among all levels of muscle activity.

CONCLUSION AND DISCUSSION

Voluntary contraction of the lumbar extensor muscles will result in an increase in lumbar PA stiffness even at low levels of activity.

Treatment of mandibular angle fractures with a malleable noncompression miniplate

PURPOSE

This study evaluated the results in patients treated for fractures of the mandibular angle with a single, thin, malleable miniplate designed for use in the midface.

PATIENTS AND METHODS

Forty-six patients with 51 fractures of the mandibular angle were treated by open reduction and internal fixation using one noncompression, thin, malleable miniplate and 1.3-mm self-threading screws placed through a transoral incision. No patient was placed into postsurgical maxillomandibular fixation. They were prospectively studied for complications.

RESULTS

Seven patients (15.2%) experienced complications. All were considered minor and did not require hospitalization. Three had asymptomatic fracture of the bone plate, but at the time of diagnosis the fracture had already healed and it required no treatment. Two patients had fracture of the bone plate with continued fracture mobility requiring maxillomandibular fixation. Three minor infections occurred requiring intraoral incision and drainage.

CONCLUSIONS

The use of this small bone plate for fractures of the angle of the mandible provided adequate fixation in most cases but was associated with an unacceptable incidence of plate fracture. However, the results also indicate that the fixation requirements for angle fractures is less than previously thought.