Treatment measures of hemimandibular hyperplasia and associated facial deformities

Late Outcomes of Undiagnosed Unilateral Condylar Hyperplasia and Reoccurrence of Mandibular Asymmetry

Unilateral condylar hyperplasia (UCH) is a rare cause of asymmetrical mandibular overgrowth because of the presence of an atypical growth in the affected condyle. SPECT (single-photon emission computed tomography) can easily establish the presence of an atypical, prolonged growth exceeding far beyond normal condylar growth and activity. A CT, CBCT, or LDCT (computed tomography, cone-beam computed tomography, or low-dose computed tomography) can confirm the diagnosis by evaluating the scope of bone overgrowth, mandibular basis/ramus asymmetry, tendency to condylar head enlargement, changes in bone density, and occurrence of differences in condylar head shapes, size, and bone structure. In most cases, a condylectomy is the procedure of choice in growing cases of UCH to remove the pathological condyle and reduce asymmetry levels. Sometimes, the growth is very slow and progressive over time, causing slowly growing asymmetry with similar symptoms to any other mandibular asymmetry, and this causes some troublesome procedures in UCH diagnostics, resulting in patients being underdiagnosed; it can even lead to some relapses in mandibular asymmetry and skeletal malocclusion after previously performed orthodontic and surgical treatment of such discrepancies. When the source of asymmetry is not identified in time, possible inadequate treatment protocols can be used. If any relapse of facial and mandibular asymmetry re-occur, SPECT and CT evaluation are necessary to evaluate if condylar hyperplasia is present and to establish what kind of surgical intervention should be used in each case.

Inferior Alveolar Nerve Repositioning With the Computer-Aided Design in Hemimandibular Hyperplasia

A 34-year-old man presented with facial asymmetry and was diagnosed with left-sided hemimandibular hyperplasia. Orthognathic surgery and mandibular angle osteotomy combined with inferior alveolar nerve repositioning were performed with computer-aided design. The facial asymmetry was successfully corrected with acceptable cosmetic results. Inferior alveolar nerve repositioning provided sufficient space for the osteotomy of the affected side with the abnormal mandibular canal. Inferior alveolar nerve repositioning with computer-aided design can be used as an effective and reliable technique for hemimandibular hyperplasia.

Single photon emission computed tomography (SPECT) diagnostic accuracy in active unilateral condylar hyperplasia: Retrospective study

The aim of this study was to assess the diagnostic accuracy of single photon emission tomography (SPECT) in unilateral condylar hyperplasia (UCH). To this end, 3D morphometric changes of the mandibles in one year were assessed (T0 vs. T1) and compared over SPECT results in T1, in a sample of 40 patients. A contingency table was constructed based on these results for SPECT diagnostic accuracy evaluation, classifying patients as SPECT true-positive, true-negatives, false positives and false-negatives. Additionally, the morphometric analysis was used to describe the presentation of mandibular changes using principal component analysis (PCA) and non-parametric statistics. We obtained diagnostic accuracy results of sensitivity 81%, specificity 63%, positive predictor value (PPV) 59%, negative predictor value (NPV) 83% and accuracy 70%, showing that SPECT yields poor results regarding accuracy diagnostic performance. The morphometric analysis showed that individuals without progress of asymmetry and those with more progress differ particularly in a group of landmarks representing the mental region and the right mandibular body. Based on these landmarks, difference among the four SPECT-accuracy groups was statistically significant (p < 0.001), where the landmark showing the largest change within a year had a mean increase of 1.13 + 0.66 mm. Within the limitations of the study, it seems that SPECT alone is not suitable for making surgical decisions regarding condylectomy in active UCH. Follow up with morphological assessment methods are recommended for confirming an active UCH in combination with SPECT.

Evaluation of treatment with unilateral mandibular sagittal split ramus osteotomy and maxillary osteotomy in patients with condylar osteochondroma and mandibular asymmetry: A retrospective case series

The aim of the study was to describe an approach where condylar resection with condylar neck preservation was combined with Le Fort I osteotomy and unilateral mandibular sagittal split ramus osteotomy (SSRO). Patients with a unilateral condylar osteochondroma combined with dentofacial deformity and facial asymmetry who underwent surgery between January 2020 and December 2020 were enrolled. The operation included condylar resection, Le Fort I osteotomy and contralateral mandibular sagittal split ramus osteotomy (SSRO). Simplant Pro 11.04 software was used to reconstruct and measure the preoperative and postoperative craniomaxillofacial CT images. The deviation and rotation of the mandible, change in the occlusal plane, position of the "new condyle" and facial symmetry were compared and evaluated during follow-up. Three patients were included in the present study. The patients were followed up for 9.6 months on average (range, 8-12). Immediate postoperative CT images showed that the mandible deviation and rotation and occlusion plane canting decreased significantly postoperatively; facial symmetry was improved but still compromised. During the follow-up, the mandible gradually rotated to the affected side, the position of the "new condyle" moved further inside toward the fossa, and both the mandible rotation and facial symmetry were more significantly improved. Within the limitations of the study it seems that for some patients a combination of condylectomy with condylar neck preservation and unilateral mandibular SSRO can be effective in achieving facial symmetry.

Long-term three-dimensional condylar remodeling during presurgical orthodontics and after orthognathic surgery of mandibular retrognathia with high mandibular plane angle

OBJECTIVES

Patients with high mandibular plane facial morphology are the most dominant facial type who experience TMJ abnormalities with resultant condylar resorption, affecting the orthodontic and orthognathic treatment outcomes. The study aimed to quantitatively assess the three-dimensional condylar remodeling during the presurgical orthodontics and after orthognathic surgery of the retrognathic mandible with a high mandibular plane angle. The study also investigated the correlation between the resultant remodeling based on the hypothesis that condylar resorption following orthognathic surgery is a part of a progressive presurgical resorption process.

MATERIALS AND METHODS

The study included adults with mandibular retrognathism and high mandibular plane angle who have computed tomography scans (CT) obtained before any treatment (T0), after completion of presurgical treatment before surgery (T1), and at long-term follow-up after surgery (T2). DICOM of CT scan was gathered and processed using ITK-SNAP and 3D Slicer software. The interval between T0 and T1 was represented as a presurgical phase, while between T1 and T2 was defined as a postsurgical phase (T1-T2).

RESULTS

Twenty-five patients (50 condyles) were included with a mean age of 23 ± 3.2 years. The mean of the follow-up during the presurgical phase was 19.8 ± 7.1 months and 15.5 ± 5.5 months during the postsurgical phase. The condylar volume during the presurgical phase (T0-T1) was relatively stable (- 3.3 ± 37.2mm³). However, during the postsurgical phase (T1-T2), the volume was significantly reduced - 113.8 ± 98.3mm³ (P < 0.001). Localized condylar surface resorption during the postsurgical phase was significantly higher than during the presurgical phase (P < 0.05). No correlation was found between the localized condylar surface remodeling during the presurgical and postsurgical phases. However, a negative statistically significant correlation existed between the overall condylar volume changes during the presurgical and postsurgical phases (r = 0.502, P < 0.001).

CONCLUSION

Significant condylar resorption following orthognathic surgery of the retrognathic mandible with a high mandibular plane angle might occur regardless of the presurgical status of the condyle.

CLINICAL RELEVANCE

The study provided an evidence to be discussed with the patients and considered throughout the treatment of mandibular retrognathia with high mandibular plane angle.

Can electrocautery of the mandibular condyle effectively treat condylar hyperplasia?

This study aims to introduce and evaluate a novel technique to treat unilateral condylar hyperplasia (UCH) by electrocauterization of the mandibular condyle via an intraoral approach. Patients suffering from unilateral condylar hyperplasia (UCH) were included in this study. All patients underwent electrocauterization of the affected condyle. An intraoral incision on the anterior border of the mandibular ramus was made to expose the external surface of the ramus and access the anterior border of the condylar head. A hole was then drilled into the condyle and cauterization was performed; six patients also received orthognathic surgery during the procedure. Patients underwent careful clinical assessment and radiological evaluation including panoramic view, lateral and posteroanterior cephalometry, cone-beam computed tomography (CBCT) and scintigraphy to assess condylar growth for a period of 12-24 months. Ten patients (5 male and 5 female) with active UCH type 1B or 2A were included in this study with a mean age of 20.7 years (range, 18-21.7 years). At the 12-month postoperative assessment, clinical evaluation showed stable dental occlusion with no midline shift; scintigraphy showed persistently reduced cellular activity, and computed tomography scans revealed no degeneration in either of the condyles with complete healing of the drilled holes. Within the limitations of this study it seems that the proposed treatment approach might be an alternative to previously established protocols.

Three-dimensional condylar displacement and remodelling following correction of asymmetric mandibular prognathism with maxillary canting

The aim of this study was to investigate the three-dimensional condylar displacement and long-term remodelling following the correction of asymmetric mandibular prognathism with maxillary canting. Thirty consecutive patients (60 condyles) with asymmetric mandibular prognathism >4 mm and occlusal canting >3 mm, treated by Le Fort I osteotomy and bilateral sagittal split ramus osteotomy, were included. Spiral computed tomography scans obtained at different periods during long-term follow-up (mean 17 ± 7.2 months) were gathered and processed using ITK-SNAP and 3D Slicer. The condyles were subjected to translational and rotational displacements immediately after the surgery (T2), which had not fully returned to the original preoperative positions at the last follow-up (T3). Condylar remodelling was observed at the last follow-up (T3), with the shorter side condyles subjected to higher surface resorption and overall condylar volume loss. The overall condylar volume on the shorter side was significantly reduced compared to the volume on the elongated side (-11.9 ± 90.6 vs -131.7 ± 138.2 mm³; P = 0.001). About 73%, 87%, 53%, and 54% of the shorter side condyles experienced resorption on the posterior, superior, medial, and lateral surfaces, respectively; in contrast, only 50% of the elongated side condyles showed resorption on the superior surface. Higher preoperative asymmetry was significantly correlated with increased postoperative condylar displacement (P < 0.05). The vertical asymmetry and the vector of condylar displacement were associated with the resultant remodelling process. It is concluded that condylar resorption of the shorter side condyle, which may affect the long-term surgical stability, has to be considered.