Review and Classification Update: Unilateral condylar hyperplasia

Comparison of knee joint and temporomandibular joint development in pig embryos

Although the knee joint (KNJ) and temporomandibular joint (TMJ) all belong to the synovial joint, there are many differences in developmental origin, joint structure and articular cartilage type. Studies of joint development in embryos have been performed, mainly using poultry and rodents. However, KNJ and TMJ in poultry and rodents differ from those in humans in several ways. Very little work has been done on the embryonic development of KNJ and TMJ in large mammals. Several studies have shown that pigs are ideal animals for embryonic development research. Embryonic day 30 (E30), E35, E45, E55, E75, E90, Postnatal day 0 (P0) and Postnatal day 30 (P30) embryos/fetuses from the pigs were used for this study. The results showed that KNJ develops earlier than TMJ. Only one mesenchymal condensate of KNJ is formed on E30, while two mesenchymal condensates of TMJ are present on E35. All structures of KNJ and TMJ were formed on E45. The growth plate of KNJ begins to develop on E45 and becomes more pronounced from E55 to P30. From E75 to E90, more and more vascular-rich cartilage canals form in the cartilage regions of both joints. The cartilaginous canal of the TMJ divides the condyle into sections along the longitudinal axis of the condyle. This arrangement of cartilaginous canal was not found in the KNJ. The chondrification of KNJ precedes that of TMJ. Ossification of the knee condyle occurs gradually from the middle to the periphery, while that of the TMJ occurs gradually from the base of the mandibular condyle. In the KNJ, the ossification of the articular condyle is evident from P0 to P30, and the growth plate is completely formed on P30. In the TMJ, the cartilage layer of condyle becomes thinner from P0 to P30. There is no growth plate formation in TMJ during its entire development. There is no growth plate formation in the TMJ throughout its development. The condyle may be the developmental center of the TMJ. The chondrocytes and hypertrophic chondrocytes of the growth plate are densely arranged. The condylar chondrocytes of TMJ are scattered, while the hypertrophic chondrocytes are arranged. Embryonic development of KNJ and TMJ in pigs is an important bridge for translating the results of rodent studies to medical applications.

Post-condylectomy orthodontic treatment for a severe asymmetrical open bite in a condylar hyperplasia patient

A satisfactory treatment of an 18-year-old lady was reported with right combination-type condylar hyperplasia (CH) in active phase. The chin severely deviated to the left, with the right gonial angle locating at a lower level. Intraorally, the lower centre line shifted to the left, the scale of which reached the width of one lower incisor. The right molar relation was mesial. Right maxillary second molar over-erupted without contact to lower teeth. There had been 2.5-mm anterior open bite (AOB) before surgery (T1) due to the tongue-spitting habit. After judging the benefits and disadvantages of all treatment alternatives, the decision was made to perform a right condylectomy and post-surgery orthodontics. Before orthodontics (T2) when the chin was positioned centred, an asymmetrical open bite occurred, caused by pre-contact between the right maxillary and mandibular second molars. Meanwhile, the AOB at T2 became 11.5mm. Orthodontic-related treatment included four premolars extraction and intrusion of bilateral maxillary molars using four miniscrews. Finally, this treatment achieved a clinically centred chin with two gonial angles at the same level. Post-condylectomy, the large AOB was resolved, together with a bilateral neutral molar relationship and alignment of the incisor midlines. Besides, the resected right condyle was covered by a continuous cortex bone and returned to the glenoid fossa. In sum, a high-challenging combined-type CH case was accomplished with impressive improvement in facial and occlusal symmetry, thanks to condylectomy and post-surgery miniscrew-assisted orthodontics.

A proposed protocol for correlation between bone density in hemimandibular hyperplasia radiography and histopathological findings - A retrospective study

The role of low-dose computed tomography (LDCT) in surgical planning can be assessed based on the correlation among bone density (BD/HU), radiographic values, and the histopathological appearance of hyperplastic overgrowth in mandibular condyles (hemimandibular hyperplasia/osteochondroma). The aim of this study was to evaluate the correlation between LDCT indices of bone-density measurements in surgical planning and histopathological specimens. The patients incuded in this study underwent detailed radiological evaluation as preparation for further clinical procedures. Excised condyles were evaluated in terms of bone density index using LDCT, and then histopathologically to investigate the accuracy of surgical procedures and set the basis for future surgical planning. An index value between both condyles' bone densities represented the relative difference between the healthy condyle and the side with hemimandibular hyperplasia (HH). Patients with unilateral condylar hyperplasia (UCH) showed a statistical correlation between condyle heads with increased bone density (BD) and scintigraphic (SCI) values (p < 0.001). On the other hand, correlation between BD and histopathological studies alone was significant (p < 0.001). With the increase in BD measured in HU in UCH condyles, the overall value of fibrous cartilage layer thickness decreased (p < 0.001). Furthermore, histopathological evaluation indicated that increased bone density on the UCH side resulted in increased total thickness (p > 0.001). The proposed index measurements in the mandibular condyles based on LDCT/BD can be used to estimate the degree of required surgical resection. Results from LDCT radiographic studies correlate with histopathological specimens more than scintigraphy.

Condylar Hyperplasia: Case Report and Literature Review

Condylar hyperplasia is a rare pathology characterised by excessive bone growth that presents virtually unilaterally, resulting in facial asymmetry. The aetiology of this disorder is not well understood. This pathology has been reported to be a rare entity with very few cases being reported in the literature, mostly seen between 11 and 30 years of age, with males and females being equally affected and having no predominance to the left or right side. It has also been reported to be a self-limiting condition, that is, the active growth can cease at any point in time. We report two cases of unilateral condylar hyperplasia in 24- and 19-year-old male and female patients, where the first was treated by condylectomy and BSSO, and the latter was treated by high condylectomy and recontouring of the mandible.

Association Between Gender, Age, and Skeletal Class With Mandibular Condyle Morphology: A Retrospective Study

OBJECTIVES

This study aimed to examine the impact of demographic variables on mandibular condyle morphology, a critical factor in orthodontic treatment and maxillofacial surgery. The investigation focuses on the relationship between gender, age, and skeletal class with the morphological dimensions of the condyle, utilizing panoramic radiography as a diagnostic tool.

METHODOLOGY

A retrospective analysis was conducted on 150 panoramic radiographs from individuals stratified into six groups according to gender and skeletal class. Skeletal classes were determined using Steiner and McNamara cephalometry. The Kodak Carestream software (Rochester, NY: Carestream Health) was employed to measure condylar height, width, and morphology. Statistical evaluations included ANOVA, correlation assessments, and multivariate binary logistic regression to discern the differences and associations among the variables studied.

RESULTS

The findings revealed notable differences in condylar dimensions between genders across different skeletal classes, with males typically presenting larger condylar dimensions than females. The data also showed a moderate positive correlation between condyle height and width. Round-shaped condyles were the most common form found, with significant gender differences observed in certain skeletal classes. Additionally, logistic regression analysis identified significant associations between gender, age, and condylar width and shape.

CONCLUSIONS

The study concludes that demographic factors, such as gender and age, significantly affect mandibular condyle morphology. These factors should be carefully considered in clinical evaluations using panoramic radiography to enhance the precision of diagnoses and the effectiveness of subsequent orthodontic and maxillofacial treatments. The results provide valuable insights for healthcare professionals in regions where more advanced imaging techniques may not be readily available.

Evaluation of optimal single-photon emission computed tomography reference value and three-dimensional mandibular growth pattern in 54 Chinese unilateral condylar hyperplasia patients

BACKGROUND

The research aimed to evaluate the optimal Single-Photon Emission Computed Tomography (SPECT) cut-off value in differentiating condylar growth activeness, to observe 3-dimensional (3D) mandibular growth pattern, and to explore the potential correlation between 3D measurement parameters and SPECT uptake ratios in Chinese unilateral condylar hyperplasia (UCH) patients.

METHODS

 Data of fifty-four Chinese UCH patients were analyzed retrospectively. All patients underwent SPECT within 1 month before or after the first CT examination (CT1); and received a second CT examination at least 12 months later (CT2). Data from CT scans were analyzed by comparing bilateral differences between CT1 and CT2. The sensitivity and specificity of SPECT were calculated by the receiver operating characteristic (ROC) curve. Pearson's correlation analysis was performed to investigate whether the mandibular growth was correlated with SPECT value.

RESULTS

SPECT had a sensitivity of 68.00% and a specificity of 72.41%, with an area under the ROC curve being 0.709. The optimal SPECT cut-off value for evaluating condylar activity has been determined to be 13%. In patients with an active growing condyle, there was a significant increase in Co-Gn and Co-Go, but not in Go-Gn, Go-MF, or MF-Gn. Pearson's correlation analysis revealed no correlation between 3D measurement parameters and differences in relative condylar uptake ratios.

CONCLUSION

SPECT showed good diagnostic performance in UCH with the cut-off value of 13%. For those with an active growing condyle, the mandible grows diagonally and vertically, while the relative condylar uptake ratio was not directly related to mandibular growth.

What Features on Routine Panoramic Radiographs Could Help Orthodontists to Estimate the Occurrence of Condylar Hyperplasia from Other Mandibular Asymmetries—Retrospective Analysis Study

Hemimandibular hyperplasia (HH) and elongation (HE) are the most common pathologies present in the mandible. Presented condylar hyperplasias have their own radiological and clinical features. In most cases, patients suffer from various forms of malocclusion. From a total of 150 asymmetrical jaw radiographs evaluated, 46 were evaluated and included in this study. A retrospective study on the data of 46 selected patients treated, diagnosed, and consulted from various forms of mandibular and skeletal asymmetry based on routine diagnostic panoramic radiographs evaluated typical and atypical radiological and anatomical symptoms of condylar hyperplasia. The presented evaluation focused on mandibular, maxillary, and other bones, in order to distinguish condylar hyperplasia from other forms of mandibular asymmetry. The degree of maxillary downward growth followed by the occurrence of an open bite on the affected side estimate the degree/presence or cessation of growth in the affected condyle. Mandibular asymmetry with incisor teeth inclination remains the most typical characteristic of condylar hyperplasia. Increased height of mandibular ramus differentiates between condylar hyperplasia and elongation, which also influences the position of the inferior alveolar nerve. Mentioned symptoms, described as the acronym “Go Moira!”, are useful in a quick and simple “glimpse of an eye” differential diagnostic approach. It is possible to quickly and accurately establish the first diagnosis simply by a careful evaluation of patients’ panoramic radiographs.

[Clinical and imagenological evaluation of the temporomandibular joint in patients undergoing condylectomy for the treatment of unilateral hyperplasia. Case series study]

Unilateral condylar hyperplasia is a non-neoplastic and self-limiting overgrowth of the mandibular condyle that usually begins during puberty, predominates in women and is considered an aberration of the normal growth mechanism of the condyle. This abnormal growth continues until the mid-20s and produces mandibular prognostism, facial and occlusal asymmetry with progressive displacement of the mandible to the contralateral side. The purpose of this report was to describe the cases of two female patients (23 and 25 years old) with unilateral condylar hyperplasia treated with high condylectomy and orthognathic surgery, with emphasis on clinical and imaging aspects and late post-surgical follow-up. Both patients presented satisfactory cosmetic results, without pain / noise related to the temporomandibular joint, mouth opening within the normal range, and class I canine and molar relationship. Computed tomography showed signs of remodeling in the affected condyle. High condylectomy combined with orthognathic surgery is an adequate treatment in cases of unilateral hyperplasia, restoring functionality and aesthetics to the patient. The bone remodeling observed in the intervened condyles seems to indicate that the condylar head maintains its adaptive capacity even in adult patients.

Unilateral Condylar Hyperplasia With Active Bony Overgrowth: A Case Report

Condylar hyperplasia (CH) is an overgrowth disorder of the temporomandibular joint bones caused by growth center overactivity of the mandibular condyle. Although the disorder is mostly idiopathic, several etiologies have been proposed. CH presents as progressive facial asymmetry with functional abnormalities. A combination of clinical, histopathological, and radiological findings is crucial to determine the diagnosis. Several diagnostic algorithms have been described in the literature. Management of CH is variable and depends on the growth of the bone. Here, we present the case of a 36-year-old female who presented with progressive facial asymmetry which was diagnosed as unilateral CH with active bony overgrowth.

Symmetry and Aesthetics in Dentistry

Animal bodies in general and faces in particular show mirror symmetry with respect to the median-sagittal plane, with exceptions rarely occurring. Bilateral symmetry to the median sagittal plane of the body also evolved very early. From an evolutionary point of view, it should therefore have fundamental advantages, e.g., more effective locomotion and chewing abilities. On the other hand, the recognition of bilaterally symmetric patterns is an important module in our visual perception. In particular, the recognition of faces with different spatial orientations and their identification is strongly related to the recognition of bilateral symmetry. Maxillofacial surgery and Dentistry affect effective masticatory function and perceived symmetry of the lower third of the face. Both disciplines have the ability to eliminate or mitigate asymmetries with respect to form and function. In our review, we will demonstrate symmetric structures from single teeth to the whole face. We will further describe different approaches to quantify cranial, facial and dental asymmetries by using either landmarks or 3D surface models. Severe facial asymmetries are usually caused by malformations such as hemifacial hyperplasia, injury or other diseases such as Noma or head and neck cancer. This could be an important sociobiological reason for a correlation between asymmetry and perceived disfigurement. The aim of our review is to show how facial symmetry and attractiveness are related and in what way dental and facial structures and the symmetry of their shape and color influence aesthetic perception. We will further demonstrate how modern technology can be used to improve symmetry in facial prostheses and maxillofacial surgery.

Acquired Facial, Maxillofacial, and Oral Asymmetries—A Review Highlighting Diagnosis and Management

Facial asymmetry refers to the absence of, or the deviation from the regular mirror image of facial structures, relative to a referenced midline axis. It can be attributed to a wide spectrum of deformities, including congenital, developmental, or acquired conditions, which can originate either prenatally or postnatally. Though highly prevalent, asymmetry commonly goes undiagnosed due to its subtle or relative nature. Among the spectrum of conditions, acquired cases are triggered postnatally, in previously normal individuals, thus subjecting them to sudden, eventful psychological and psychosocial disharmony. When detected early, timely management may help intervene progressive growth of these conditions. This, therefore, emphasizes the need for a thorough diagnostic workup including medical/dental history, clinical examinations, study models, photographic and radiographic records for a case-by-case basis to prevent severe functional and aesthetic complications. Recently, advanced diagnostic procedures, such as stereophotogrammetry, 3D stereolithographic models, skeletal scintigraphy (radionucleotide scans), 3D computed tomographic scans, cone-beam computed tomography, and magnetic resonance imaging, have provided innovative diagnostic instruments for numerous craniofacial defects. This descriptive review aims at focusing on the factors leading to frequently encountered conditions of acquired facial asymmetry and highlights their clinical evaluation, conservative and surgical interventions by a multi-disciplinary team of clinicians.

Unilateral Condylar Hyperplasia: Two Case Reports and a Literature Review

Condylar hyperplasia (CH) is a rare idiopathic condition affecting the mandibular condyle where the growth of the condylar head and/or neck continues beyond the normal growth period. The disorder presents clinically as facial asymmetry and occlusal discrepancy. Here, we present two cases of CH managed at our centers between 2012 and 2017 with a successful outcome. We highlight the clinical presentation, investigation, and surgical management and give a brief literature review.

Analysis of Three-Dimensional Morphological Differences in the Mandible between Skeletal Class I and Class II with CBCT Fixed-Point Measurement Method

This study was aimed at determining the three-dimensional differences in the mandible morphology between skeletal class I and II patients, at exploring the pathogenic mechanisms and morphological characteristics of skeletal class II, and at providing clinical references. The subjects were assigned to two groups according to the size of ANB angle: skeletal class I (2° < ANB angle < 5°) and skeletal class II (5° < ANB angle < 8°). After cone-beam computed tomography (CBCT) scanning, 31 landmarks and 25 measurement items were determined by In Vivo Dental 5.1 software (Anatomage, CA) for statistical analysis. The results were as follows: Co-Go, Go-Me, and CdM-CdD in skeletal class II cases were smaller than those in skeletal class I, and GoR-Me-GoL, GoR-Me-CoL, and, Ig-Men were larger than those in skeletal class I cases. In conclusion, there were significant differences in the three-dimensional morphology of the mandible between skeletal class I and class II patients. The vertical growth of the ramus, the horizontal growth of the mandibular body, and the condyle in skeletal class II patients were smaller than those in skeletal class I cases. In skeletal class II, the growth of the anterior part of the mandible in the vertical direction was larger than that in skeletal class I, and the shape of the mandible was more extended.

Concurrent High Condylectomy and Orthognathic Surgery for Treatment of Patients With Unilateral Condylar Hyperplasia

BACKGROUND

Facial asymmetry from unilateral condylar hyperplasia (UCH) may be definitively treated in the presence of active disease (with high condylectomy and concurrent orthognathic surgery) or after waiting for disease inactivity (orthognathic surgery alone). There is currently no consensus on the standard of care. In this study, we sought to compare functional and esthetic outcomes, as well as treatment duration, between these 2 management options.

METHODS

Patients who underwent treatment for UCH were identified through retrospective review. Pre- and postoperative 3-dimensional (3D) images were obtained. Short- and long-term operative outcomes of those treated during the active (group 1) were compared to those treated in the inactive phase (group 2). Total treatment time, operative time, and length of hospital stay were evaluated. Facial asymmetry was also assessed by laypersons using a Likert scale.

RESULTS

Fifteen patients (mean 25.6 years, range 14-56) were included: 6 in group 1 and 9 in group 2. All surgical outcomes were statistically independent of procedure type. Treatment time was significantly longer in the group 2 (P = 0.03). Both groups demonstrated significant improvement in facial asymmetry scores postoperatively with no significant difference in pre- or postoperative asymmetry between groups (P = 0.64).

CONCLUSIONS

In patients with active UCH, high condylectomy and orthognathic surgery is a procedure that restores facial symmetry and improves jaw function while halting mandibular growth. Good esthetic and functional outcomes, as well as reduced treatment time and disease burden, support the use of this treatment option for this population.

Facial Asymmetry in Unilateral Condylar Hyperplasia: Comparing Treatment for Active versus Burnt-Out Disease

BACKGROUND

Facial asymmetry caused by unilateral condylar hyperplasia requires treatment to address facial and occlusal imbalances. There is no definitive evidence to suggest that a single intervention strategy (during either active condylar overgrowth or the burnt-out phase) results in better/more symmetric correction. This study sought to quantify preoperative and postoperative facial asymmetry in unilateral condylar hyperplasia patients comparing treatment for active versus burnt-out disease.

METHODS

Preoperative and postoperative three-dimensional photographs were obtained. Images were compared to those of unaffected controls as a standard for normal facial symmetry. Facial asymmetry was assessed using root-mean-square deviation. Paired t tests were performed to compare the root-mean-square deviations of preoperative and postoperative images between the unilateral condylar hyperplasia groups and against controls.

RESULTS

Forty patients were included (11 active, nine burnt-out, and 20 controls) and 60 three-dimensional images were evaluated. Preoperatively, patients in the burnt-out group had worse asymmetry than those with active unilateral condylar hyperplasia (p = 0.011). Both groups demonstrated significantly improved symmetry postoperatively (active, p = 0.0069; burnt-out, p = 1.74E-4). However, burnt-out patients remained with some residual asymmetry (p = 4.75E-4), whereas their active counterparts showed no significant difference compared to unaffected controls (p = 0.089).

CONCLUSIONS

Patients with end-stage unilateral condylar hyperplasia have more severe facial asymmetry that is more difficult to normalize compared to earlier intervention during active unilateral condylar hyperplasia. These findings suggest that, if possible, corrective intervention is preferable during active unilateral condylar hyperplasia.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.