D.B. Tuinzing

Condylar remodelling and resorption after le Fort I and bimaxillary osteotomies in patients with anterior open bite

A sample of 259 patients with vertical maxillary hyperplasia, mandibular hypoplasia and anterior vertical open bite, collected from three different institutions, was analysed regarding temporomandibular joint (TMJ) sounds, condylar remodelling, and condylar resorption. All patients underwent Le Fort I osteotomies, and bilateral sagittal split advancement osteotomies were performed in 117 patients. Intraosseous wire fixation was used in 149 and rigid internal fixation in 110 patients. Cephalometric and orthopantomographic radiographs were available before surgery, immediately after surgery, one year postoperatively and at the latest follow up. The mean follow up was 69 months (range 20-210 months). The number of patients with TMJ sounds decreased from 38% to 31%. At the latest follow up 23.6% of the patients showed condylar remodelling, 7.7% unilateral condylar resorption and 7.7% bilateral condylar resorption. Condylar contours, as assessed on orthopantomographic radiographs, were classified as five different types. Condyles with preexisting radiological signs of osteoarthrosis or having a posterior inclination were at high risk for progressive resorption. Female patients with severe anterior open bite, high mandibular plane angle and a low posterior-to-anterior facial height ratio, who underwent a bimaxillary osteotomy, were prone to condylar resorption. Bone loss was predominantly found at the anterior site of the condyle. The incidence of condylar resorption was significantly higher after bimaxillary osteotomies (23%) than after only Le Fort I intrusion osteotomies (9%). Avoidance of intermaxillary fixation by using rigid internal fixation tended to reduce condylar changes, in particular in patients who underwent only a Le Fort I osteotomy. Rigid internal fixation in bimaxillary osteotomies resulted in condylar remodelling in 30% and progressive condylar resorption in 19% of the patients. Condylar changes were not significantly different after using either miniplate osteosynthesis or positional screws in bilateral sagittal split osteotomy procedures.

Skeletal and dento-alveolar stability of Le Fort I intrusion osteotomies and bimaxillary osteotomies in anterior open bite deformities: A retrospective three-centre study

A sample of 267 patients with maxillary hyperplasia, a Class I or Class II/I occlusion and anterior vertical open bites, collected from three different institutions, was analysed regarding stability after surgical corrections. Skeletal and dento-alveolar stability of the maxilla, and positional changes of the mandible and of the incisors were evaluated. All patients underwent Le Fort I intrusion osteotomies and in 92 patients segmentation of the maxillae was performed. An additional bilateral sagittal split advancement osteotomy was performed in 123 patients. Intraosseous wire fixation was used in 153 patients and rigid internal fixation in 114 patients. Cephalometric radiographs were collected before orthodontic treatment, before surgery, immediately after surgery, one year postoperatively and at the latest follow up. The mean follow up was 69 months (range 20-210 months). It can be concluded that patients with anterior open bites, treated with a Le Fort I osteotomy in one-piece or in multi-segments, with or without bilateral sagittal split osteotomy, exhibited good skeletal stability of the maxilla. Rigid internal fixation produced the best maxillary and mandibular stability. The mean overbite at the longest follow up was 1.24 mm and a lack of overlap between opposing incisors was present in 19%. The overbite did not differ significantly between the different treatment procedures, probably due to compensatory movements of the mandibular and maxillary incisors.

Condylar resorption in orthognathic surgery: The role of intermaxillary fixation

Condylar resorption that occurs after orthognathic surgery was investigated in a large sample of patients treated in the Department of Oral and Maxillofacial Surgery of the Free University in Amsterdam, the Netherlands. The findings correspond with previous publications on this subject. In a 1-year follow-up study the role of intermaxillary fixation was investigated radiologically. In a group of 158 patients prone to show occurrence of condylar resorption, 24 (26.4%) of the 91 patients treated with intermaxillary fixation showed signs of condylar resorption. In the group of 67 patients treated without intermaxillary fixation only eight (11.9%) of the patients showed signs of reduced volume of the condyle. Avoidance of intermaxillary fixation seems to reduce the incidence of condylar resorption after orthognathic surgery in patients with a mandibular deficiency with high mandibular plane angle.

Bone scintigraphy as a diagnostic method in unilateral hyperactivity of the mandibular condyles: a review and meta-analysis of the literature

Bone scan analyses and clinical assessment are used to diagnose unilateral condylar hyperactivity (UCH). This review compares the diagnostic accuracy of planar and SPECT bone scans. Studies diagnosing patients with possible UCH using bone scans, published between 1968 and 2008, were included in this review. Of 15 articles that met the inclusion criteria, 7 presented results in sufficient detail to calculate index test characteristics. Three control studies show that the difference in uptake values of the left and right condylar regions in the normal population does not exceed 10%. The pooled sensitivity of the planar bone scan (n=130) was 0.71 (95% confidence interval: 0.57-0.82), which was significantly lower (p=0.04) than that of the bone SPECT technique (n=88), which was 0.90 (0.79-0.97). The pooled specificity of the SPECT scan was 0.95 (0.82-0.99), which did not significantly differ (p=0.58) from that of the planar scan (0.92 (0.83-0.97)). Future studies should include a diagnostic analysis of the data, including two-by-two contingency tables, so the accuracy of the diagnostic test may be evaluated. Bone scans are best performed using SPECT, conducting a quantitative analysis by calculating the percentile differences between the left and right condylar regions.

No signs of metabolic hyperactivity in patients with unilateral condylar hyperactivity: an in vivo positron emission tomography study

PURPOSE The purpose of this study was to assess bone growth and blood flow in the condylar region in patients with unilateral condylar hyperactivity (UCH) by use of positron emission tomography (PET). PATIENTS AND METHODS This prospective study included 7 patients with UCH and a control group of 6 volunteers. In addition to normal clinical investigations, labeled fluoride ((18)F(-)) and oxygen 15-labeled water (H(2)(15)O) PET scans were performed. RESULTS In control subjects the net rate of fluoride influx, representing bone metabolism, was similar for left and right condylar sides. Interestingly, this was not significantly different from the affected condyles in UCH patients. Rather, the net rate of fluoride influx on the contralateral side of UCH patients was reduced significantly compared with the affected side (P= .02) and control subjects (P= .004). The mean blood flow on the left and right condylar sides in control subjects was not significantly different. The same was true for the hyperactive and contralateral condyles of UCH patients. Blood flow in the condylar region in UCH patients was similar to that in the control group. CONCLUSIONS There was no evidence of an abnormally high rate of bone growth in the affected condylar region in UCH patients. Instead, the rate of bone growth appeared to be reduced in the contralateral condylar region. These PET results are in contrast to the characteristic clinical picture of UCH patients and suggest the possibility of subgroups in patients with a mandibular asymmetry caused by UCH. Furthermore, no evidence of hypervascularization of the condylar region in UCH patients was found.

Comparison of planar bone scintigraphy and single photon emission computed tomography in patients suspected of having unilateral condylar hyperactivity.

OBJECTIVE A comparison is made of single photon emission computed tomography (SPECT) and planar bone scintigraphy in the diagnosis of patients with suspected unilateral condylar hyperactivity (UCH). STUDY DESIGN The subjects comprised 56 patients with suspected UCH who underwent SPECT and regular planar bone scans. Accuracy of SPECT and planar scintigraphy were compared using left-right condylar activity. RESULTS Of the 56 patients, 29 were diagnosed with active UCH and 27 without UCH. The mean relative activity of the hyperactive condylar region in the planar scans was 53.5% (SD +/- 2.3%), which was significantly higher in the SPECT scan with a mean value of 60.5% (SD +/- 5.4%), P < .005 (t = 8.951). Receiver operating curves (ROC) were clearly in favor of SPECT over the planar bone scan. The area under the curve (AUC) of the planar ROC was 0.87 +/- 0.049 while that of the SPECT ROC was 0.97 +/- 0.024. The optimal cut-off value for planar scanning was 52%, yielding a sensitivity of 67% and a specificity of 85%. For SPECT scanning, the optimal cut-off was 56%, resulting in a sensitivity of 93% and a specificity of 96%. CONCLUSIONS It can be concluded that in patients with a clinically suspected active UCH, SPECT scanning is the preferred diagnostic tool rather than planar bone scanning. However, treatment planning should be done in combination with clinical assessment of progressive mandibular asymmetry as well as taking into account the patient history.

A comparative in vitro study on fixation of sagittal split osteotomies with Würzburg screws, Champy miniplates, and Biofix (biodegradable) rods.

A bilateral sagittal split osteotomy was performed on seven fresh cadaver mandibles. Three different systems of fixation were mechanically tested on 14 sites. Tensile diagrams were obtained in which the (offset-) yield point was measured. This resulted in mean yield stresses of 199 N for bi-cortical self-tapping screws (n = 6), 49 N for miniplates with monocortical screws (n = 5), and 113 N for bi-cortical biodegradable rods (n = 3).

Unilateral condylar hyperactivity: a histopathologic analysis of 47 patients

PURPOSE To perform a histopathologic analysis of condyles that were resected because of unilateral condylar hyperactivity and compare the results of the bone scan with the histopathologic findings. PATIENTS AND METHODS A total of 47 resected condyles were histopathologically examined. In 29 cases, a single photon emission computed tomography (SPECT) bone scan was available. For all condylar specimens, a standardized histologic scoring system was used to assess the number of cartilage islands and the thickness of the cartilage layer. The SPECT scans were analyzed by calculating the difference in bone activity between the hyperactive and contralateral condyles. RESULTS The number of cartilage islands was highly variable, ranging from almost absent in 37% of the patients to abundant in 35%. Furthermore, the relative thickness of the cartilage layer exhibited considerable variation, from less than one quarter of the total thickness of the condylar articular layer in 22% of the patients to one half of the total thickness in 35%. We found no significant relationship between the number of cartilage islands and bone activity using SPECT (P = .11) or between the relative thickness of the cartilage layer and bone activity using SPECT (P = .82). CONCLUSIONS Unilateral condylar bone growth can occur without large numbers of cartilage islands and without abundant cartilage formation. The bone activity measured by bone scintigraphy was not related to the histologic results. The histopathologic findings of resected condyles in unilateral condylar hyperactivity cannot, therefore, be used as a reference standard. Nevertheless, histopathologic examination should always be performed to rule out other diseases.

Comparison of different analytical methods used for analyzing SPECT scans of patients with unilateral condylar hyperactivity

This study aimed to compare different analytical methods and identify the optimal analysis method to distinguish patients with unilateral condylar hyperactivity (UCH) from those with inactive condyles. Single-photon emission computed tomography (SPECT) scans of patients with progressive and nonprogressive mandibular asymmetry (each group, n=26), were analyzed using the region of interest technique. Sensitivity, specificity and receiver operating characteristic (ROC) curves were calculated for the different analytic methods. The ROC curve illustrates that UCH can be diagnosed significantly better by determining the percentile bone activity in both condyles. The area under the curve (AUC) of the percentile comparison between the affected and contralateral condyles was 0.93+/-0.04, that for the condyle/clivus ratio was 0.75+/-0.07 and for the condyle/cervical spine (CS) ratio 0.57+/-0.08. Sensitivity for the condyle/clivus ratio was 65% and specificity 61%. Sensitivity for the condyle/CS ratio was 85% and specificity 31%. For the percentile difference of the condyles, sensitivity and specificity were 88%. For UCH patients, direct comparison of bone activity between the affected and contralateral condyle in SPECT scans is the analysis method of choice. Comparison of condylar bone activity to reference bone activity does not have additional value in the diagnosis of UCH.

Evaluation of Temporomandibular Function After High Partial Condylectomy Because of Unilateral Condylar Hyperactivity

PURPOSE The purpose of this study was to assess temporomandibular function after condylectomy because of unilateral condylar hyperactivity (UCH) by means of standardized diagnostic criteria. The results were compared with those obtained in a control group. PATIENTS AND METHODS In this study, 33 patients with UCH who underwent condylectomy and 31 controls matched for age and gender filled out a history questionnaire and underwent a clinical examination as part of the research diagnostic criteria for temporomandibular disorders. Data analysis was performed by use of the Fisher exact test for 2-by-2 tables. RESULTS Patients and controls did not differ significantly regarding myofacial pain (P = .131), disc displacement (P = .516), and depression (P = .34). The groups differed significantly concerning arthralgia, osteoarthritis, and osteoarthrosis (P = .003), as well as pain with low disability (P = .022). CONCLUSIONS In patients with UCH who underwent condylectomy because of progressive mandibular asymmetry, more joint-related temporomandibular problems as well as more postoperative pain developed when compared with age- and gender-matched controls. However, these problems did not lead to more severe disabilities in daily life.