Temporomandibular Joint Osseous Morphology of Class I and Class II Malocclusions in the Normal Skeletal Pattern: A Cone-Beam Computed Tomography Study

Relationship between interincisal angles and TMJ morphology/position and trabecular structure: a retrospective study

BACKGROUND

TMJ morphology/position and trabecular structure are influenced by various factors. The role of the interincisal angle, an indicator of the anterior occlusal relationship, on TMJ remains unclear. This study aims to investigate the morphology, trabecular bone structure, and position of the condyle, as well as the glenoid fossa's morphology in skeletal class II populations with different interincisal angles.

MATERIALS AND METHODS

A total of 150 adult patients with normodivergent facial types and skeletal class II malocclusions were selected and divided into three groups based on their interincisal angles: normal, small, and large angle groups. The indexes of TMJ were measured using cone-beam computed tomography (CBCT) data and analyzed using Dolphin Imaging, Mimics, and ImageJ.

RESULTS

The small angle group had the smallest anteroposterior diameter (APD), while the large angle group had a greater mediolateral diameter (MLD). The large angle group exhibited significantly the largest maximum axial area, bone surface area, and bone volume (P < 0.05). Small and large angle groups exhibited greater bone trabeculae (Tb. N) and thinner trabecular thickness (Tb. Th). Compared to the normal angle group, the small angle group exhibited a larger horizontal condylar angle and smaller bilateral condylar angles on the axial plane, while the large angle group showed the opposite trend. Small and large angle groups showed a reduced vertical condyle angle on the coronal plane, with the largest reduction observed in the large angle group (P < 0.05). Small and large angle groups had higher heights of the glenoid fossa (GFH). The large angle group exhibited the greatest GFH and width of the glenoid fossa (GFW) (P < 0.05).

CONCLUSION

The large angle group had elongated oval and large condyles, and deeper glenoid fossae, while a flattened-oval and smaller condyle, and wider and shallower glenoid fossae were observed in the small angle group. Small and large interincisal angle affects the structure of condylar trabeculae, resulting in thinner Tb. Th and greater Th. N. In the condylar position, small and large angle groups exhibit condylar rotation in the axial and coronal planes. Therefore, the interincisal angle affects the morphology, position, and trabecular structure of the TMJ. This implies that we must pay attention to the impact of the interincisal angle on TMJ, and it is crucial to restore the normal interincisal angle during orthodontic treatment.

Relationship Between Occlusal Factors and Temporomandibular Disorders: A Systematic Literature Review

Temporomandibular disorders (TMD) originate from various components within the temporomandibular joint (TMJ), causing an impact on the masticatory muscles, the joint itself, and associated structures. They are a widely prevalent issue across the world. According to epidemiological research, up to 50% of adults in the population have TMD-related symptoms. The objective of this work was to analyze the existing scientific literature regarding the association between malocclusion classes, bruxism, and tooth loss in relation to the etiology of TMD. This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 analysis protocol. For the development of the question focus, the population, intervention, control, and outcomes (PICO) study design protocol was used. The question in focus according to the PICO format was: "Do malocclusion, tooth loss, and bruxism contribute to temporomandibular disorders?". The review was performed with articles from PubMed, Web of Science, and Google Scholar databases according to the specified inclusion and exclusion criteria. The included articles were not older than five years. The risk of bias was assessed in the included studies by using the Cochrane Risk-of-bias 2 (RoB-2) tool. Out of a total of 32 results received, 21 articles were chosen according to the established criteria after conducting a review and analysis of their full texts. The article search sequence was presented in the PRISMA 2020 flow diagram, and the outcomes of the chosen articles were presented. The literature results revealed a relationship between occlusion and the development of TMD. The influence of occlusal factors on the TMJ was explained by an examination of joint anatomy and symptoms related to TMD. This study revealed variations in TMJ factors across different malocclusion classes. Additionally, it was observed that the occurrence and attributes of TMD are influenced by the number of tooth loss quadrants and the frequency of missing teeth. Furthermore, a correlation was found between bruxism and the symptoms of TMD, including myofascial pain, disc displacement, arthralgia, and muscle disorders. This literature review provides comprehensive information on the relationship between malocclusion classes, bruxism, tooth loss, and TMDs. This prompts healthcare professionals to prioritize patients' occlusal assessment and TMJ condition.

Volumetric comparison of mandibular condyles and mandibles in the different skeletal classes in the Saudi population

Background

Assessing the relationship between the condyle and mandible volume and the various skeletal classes is essential in orthodontic diagnosis. The current study evaluated this relationship using volumetric cone-beam computed tomography (CBCT), cephalometric methods, and the correlations between them.

Materials and Methods

The study examined 37 full-head CBCTs (74 condyles) from adults in the Saudi population. The condyle and mandible were separated from within the CBCT images. The volume of each segment was compared to measurements from multiple cephalometric analyses.

Results

The combined total condylar volume has a moderate correlation with the maxillomandibular differential in each of the genders and in the total sample. Mandibular volume has a significant correlation with the Wits appraisal (sagittal classification) in males. It was also significantly correlated with the vertical classification using gonial angles in females and in the total sample.

Conclusion

The relationship between mandible and condyle volume and cephalometric measurements is both dimensional and within the maxillomandibular complex rather than positional or related to the cranial base. Also, the correlation between the condylar and mandibular volumes and the sagittal and vertical dimensions in the orthodontic skeletal classes provides better insight into the mandibular complex.

Changes of Temporomandibular Joint Morphology and Symptoms in Class II Malocclusion Patients With Bilateral Sagittal Split Ramous Osteotomy

This study included 46 patients with class II malocclusion ranging in age from 19 to 39 years old treated with bilateral sagittal split ramous osteotomy (BSSRO). Left and right temporomandibular joints (TMJs) of each subject were evaluated independently with cone-beam computed tomography (CBCT) before operation (T1), 1 week after operation (T2), and 1 year after operation (T3) and assessed the effects of orthognathic surgery (OGS) on the temporomandibular joint disease (TMD) symptoms. Temporomandibular joint morphology evaluation included condylar volume, condylar area, cortical bone thickness, depth of the mandibular fossa, fossa thickness, joint nodule angle, joint space, and condyle-fossa relationship, which were calculated by using the Mimics software and 3-matic software. Data were statistically analyzed with SPSS software (P <0.05 means statistically significant). In our study, bilateral TMJs have no difference in T3. Bilateral sagittal split ramous osteotomy had no significant effect on the articular fossa. The condyle volume and surface area decreased from T1 to T3, but the cortical thickness of the bone did not change significantly. More anterior condyle positions in T1 and more posterior in T3.21 patients had at least 1 sign or symptom of TMD in T1 and 27 patients in T3. Four patients who were asymptomatic in T1 developed pain after surgery, 10 developed noises, 12 showed limited mouth opening, and 8 had abnormal opening patterns. It is concluded that more condylar posterior position after BSSRO and the reduction of condyle may be related to the enlargement of anterior space. The number of patients with joint symptoms increased postoperative, and the impact of BSSRO on TMD may be negative.

Three-dimensional relationships between condylar volume and dentoskeletal characteristics in Class II hyperdivergent female adults

BACKGROUND

This study aimed to determine the differences among various volumes of condylar osseous patterns and the corresponding dentoskeletal characteristics based on the risk of temporomandibular disorder.

METHODS

Craniofacial spiral computed tomography data of 60 Class II hyperdivergent female adults were divided into normal, resorptive, flattened, and osteophyte groups based on condylar osseous forms. The condylar volumes of each group were compared, and their correlations with the dentoskeletal characteristics were assessed in three dimensions. Pairwise least significant difference tests were used to examine individual pairwise differences between groups, and one-way analysis of variance was used to measure differences among multiple groups. Pearson correlation and Spearman rank correlation analyses were used to determine the correlation between condylar volume and dentofacial characteristics. Statistical significance was established at p < 0.05.

RESULTS

The condylar volume in the normal group was significantly greater than that in the changed groups, with no significant differences between the subgroups. The decrease in condylar volume was associated with a retruded and clockwise-rotated mandible with shorter rami. Condylar volume was negatively correlated with overjet, the alveolar height of the lower anterior and posterior teeth, sagittal inclinations of the lower teeth, intermolar width of the mandibular first molars, and width between the corresponding alveolar crests.

CONCLUSION

Multiple three-dimensional dentoskeletal characteristics of Class II hyperdivergent female adults are correlated with condylar bony changes, regardless of the form. These results could be helpful in indicating potential pathological changes in the temporomandibular joint and in making proper treatment plans for these patients.

Three-Dimensional Assessment of Temporomandibular Joint Morphology and Facial Asymmetry in Individuals with Different Vertical Skeletal Growth Patterns

The aim of the current study was to investigate, by means of Cone-Beam Computed Tomography (CBCT), condyle−fossa relationship, temporomandibular joint (TMJ) morphology and facial asymmetry in subjects with different vertical skeletal growth patterns. CBCT of 56 patients (112 TMJs) were categorized into three groups according to the mandibular plane angle (MP): Hypodivergent (MP ≤ 23°), Normodivergent (23° < MP < 30°), and Hyperdivergent (MP ≥ 30°). TMJ spaces, width and depth of the condyle and thickness of the fossa were measured. Horizontal and vertical measurements were used to assess facial asymmetry. One-way Analysis of Variance (ANOVA) and post-hoc Turkey tests were computed for the between-groups comparison. Statistical significance was set at p < 0.05. Larger anterior joint space and smaller condylar dimensions (medio-lateral diameter and medio-lateral thickness) were observed in the hyperdivergent group compared to the normodivergent and hypodivergent groups. Right condylar distances to midsagittal plane were significantly larger than left distances in all the three groups. A vertical pattern of growth in healthy individuals seems to be associated with condylar position and dimension, while facial asymmetry values do not differ among different vertical groups.

Assessment of the Morphology and Degenerative Changes in the Temporomandibular Joint Using CBCT according to the Orthodontic Approach: A Scoping Review

BACKGROUND

Available knowledge about disorders of temporomandibular joint structures and their association with orthodontic variables are still lacking.

OBJECTIVES

This article is aimed at to identifying studies and presenting current information on the relationship between morphology diversity and the occurrence of degenerative changes in structures of the temporomandibular joint (TMJ) assessed by cone-beam computed tomography (CBCT) in the context of craniofacial morphology and malocclusion. Search Methods. The review was conducted by analyzing the PubMed (including Medline), Cochrane Library, Web of Science, and Scopus electronic databases up to November 2021 using two different comprehensive search strategies based on keywords as well as additional manual searches. Eligibility Criteria. Selection of the literature was carried out according to the PRISMA-ScR checklist. Methodological quality of the selected studies was evaluated using JBI Critical Appraisal Tool.

RESULTS

The electronic databases search revealed 3331 records. After applying the eligibility criteria and JBI assessment, a total of 33 studies were extracted and selected to the study. The review was divided into 4 parts, in which the following correlations were assessed in terms of orthodontic variables: TMJ degenerative changes, joint space and condylar position, condylar shape, TMJ articular eminence, and fossa.

CONCLUSIONS

Skeletal and dental class II malocclusion with a retrognathic mandible, a hypodivergent skeletal pattern with a steep mandibular plane, and significant lateral mandibular displacement can be risk factors for developing radiographically detectable degenerative changes. Patients with skeletal and dental class III malocclusion as well as a hyperdivergent skeletal pattern may be at greater risk of TMD occurrence compared with other groups. Further studies are necessary to clarify the relationship between the position of the condylar processes and the presence of degenerative changes in the temporomandibular joints among orthodontic patients.