Cephalometric keys to internal derangement of temporomandibular joint in women with Class II malocclusions

Correlation between craniocervical posture and upper airway dimension in patients with bilateral anterior disc displacement

OBJECTIVE

To investigate the relationship between upper airway dimension and craniocervical posture in adult patients with bilateral anterior disc displacement and to provide some references for clinical diagnosis and plan formulation in orthodontics.

METHODS

Based on RDC/TMD (Research Diagnostic Criteria for Temporomandibular Disorder), 98 Patients were divided into three groups by two experienced TMJ (Temporomandibular Joint) specialists: bilateral disc normal position group (BN), bilateral anterior disc displacement with reduction group (ADDWR) and bilateral anterior disc displacement without reduction group (ADDWoR). Inter-group comparison and correlation analysis were performed after 11 craniocervical posture and 15 upper airway dimension measurements finished with Dolphin and Uceph software in Two or Three-dimensional.

RESULTS

Anterior disc displacement often accompanied with extension of craniocervical posture, as ADDWR and ADDWoR groups have significantly higher cervical curvature and inclination than BN group (P < 0.05). Simultaneously anterior disc displacement often associated with constrained upper airway dimension for the total and each segment upper airway volume were significantly smaller in ADDWR and ADDWoR than BN group (P < 0.05). Correlation analysis revealed that C0-C1 (the distance from the base of the occipital bone (C0) to the posterior arch of the atlas (C1)) is significantly related to the total and each segment upper airway volume reduction (P < 0.05).

CONCLUSION

There exists markedly close correlation between anterior disc displacement and craniocervical posture forward extension, which may be physiologically adaptive cervical extension to keep oropharyngeal airway unobstructed as upper airway dimension constrained by anterior disc displacement.

CLINICAL RELEVANCE

These findings allow us to infer the potential consequences if the treatment of anterior disc displacement would result in an improvement of intervertebral relationships and upper airway constraint.

Correlation between temporomandibular joints and craniocervical posture in patients with bilateral anterial disc displacement

OBJECTIVE

To study the changes of temporomandibular joints and craniocervical posture in adult patients with bilateral anterior disc displacement, and to explore their correlation, which may provide some clinical value for clinical diagnosis and treatment planning.

METHODS

Ninety-eight adult patients were divided into 3 groups: 29 patients in bilateral disc normal position group (BN), 33 patients in bilateral Anterior Disc Displacement With Reduction group (ADDWR) and 36 patients in bilateral Anterior Disc Displacement Without Reduction group (ADDWoR). Dolphin and Uceph software were used to measure 14 items of temporomandibular joint and 11 items of craniocervical posture for comparison and correlation analysis between groups.

RESULTS

There were significant differences in bilateral joint space between three groups. Compared with the BN, the anteroposterior diameter of the condyle was significantly reduced, the condyle was significantly displaced posteriorly and superiorly in the ADDWR and ADDWoR, but the joint fossa width and joint fossa depth did not change significantly. Cervical curvature and inclination were greater in patients with anterior disc displacement than BN, indicating that the craniocervical posture of adult patients with anterior disc displacement was extended and protrusive.

CONCLUSION

Anterior disc displacement of the temporomandibular joint can displace the condyle upwards and posteriorly and reduce the anteroposterior diameter of condyle, and then make the condyle closer to the wall of articular fossa to induce joint symptoms. Additionally, craniocervical postural position is significantly affected, which may be related to compensate for the effects of airway space.

Relationship between condylar surface CT value in coronal plane and condylar morphology in jaw deformity patients

OBJECTIVES

This study aimed to examine the relationship between condylar surface computed tomography (CT) values in the coronal plane and condylar morphology in patients with jaw deformities classes II and III before and after orthognathic surgery.

MATERIALS AND METHODS

The maximum CT values (pixel values) at three points on the condylar surface, height, and joint space were measured on the coronal plane. The condylar width, thickness, and angle were measured on the horizontal plane preoperatively and at 1 year postoperatively.

RESULTS

A total of 112 temporomandibular joints of 56 female patients were divided into two groups according to skeletal class (56 joints each in class II and class III). The maximum CT values of class II were higher than those of class III at the medial, central, and lateral sites on the condylar surface, preoperatively and at 1 year postoperatively (P < 0.05). CT values of the condylar surface were significantly negatively correlated with the condylar heights at the center and lateral sites preoperatively and at 1 year postoperatively (P < 0.05).

CONCLUSIONS

Condylar surface CT values in the coronal plane are associated with condylar morphology, including condylar height.

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.

Development of a new category system for the profile morphology of temporomandibular disorders patients based on cephalograms using cluster analysis

OBJECTIVE

This study aims to develop a new category scheme for the profile morphology of temporomandibular disorders (TMDs) based on lateral cephalometric morphology.

METHODS

Five hundred and one adult patients (91 males and 410 females) with TMD were enrolled in this study. Cluster tendency analysis, principal component analysis and cluster analysis were performed using 36 lateral cephalometric measurements. Classification and regression tree (CART) algorithm was used to construct a binary decision tree based on the clustering results.

RESULTS

Twelve principal components were discovered in the TMD patients and were responsible for 91.2% of the variability. Cluster tendency of cephalometric data from TMD patients were confirmed and three subgroups were revealed by cluster analysis: (a) cluster 1: skeletal class I malocclusion; (b) cluster 2: skeletal class I malocclusion with increased facial height; (c) cluster 3: skeletal class II malocclusion with clockwise rotation of the mandible. Besides, CART model was built and the eight key morphological indicators from the decision tree model were convenient for clinical application, with the prediction accuracy up to 85.4%.

CONCLUSION

Our study proposed a novel category system for the profile morphology of TMDs with three subgroups according to the cephalometric morphology, which may supplement the morphological understanding of TMD and benefit the management of the categorical treatment of TMD.

Temporomandibular Joint Disk Displacements in Class II Malocclusion and Cervical Spine Alterations: Systematic Review and Report of a Hypodivergent Case with MRI Bone and Soft Tissue Changes

(1) Background: This study aimed to perform a literature review related to disk displacement (DD) in class II malocclusion or cervical vertebrae position alterations and to report a hypodivergent case with cervical pain and right anterolateral DD with reduction, left anterolateral DD with reduction, and left joint effusion. (2) Methods: A structured electronic search was conducted between March 2022 and April 2022, without time limits, following PRISMA guidelines, in the following databases: PubMed, Scopus, Embase and Cochrane; the terms “disc displacement”, “disk displacement”, “temporomandibular joint”, “class II malocclusion” and “cervical vertebrae” are searched. (3) Results: the following thirteen publications are included in this review: two prospective studies and eleven cross-sectional studies; for evaluating disk position, eight included publications used magnetic resonance imaging (MRI), whilst six studies used lateral cephalogram to determine craniofacial morphology and relationships between the cranial base, vertical skeletal pattern, maxilla and mandible. (4) Conclusions: although the literature still shows contradictory opinions, a relationship between temporomandibular disorders and cervical posture has been shown in the presented case as well as in the literature review.

Assessment of lateral pterygoid muscle and temporomandibular joint disc after Le Fort I osteotomy with and without intentional pterygoid plate fracture and sagittal split ramus osteotomy in class II and class III patients

The aim of the study was to examine lateral pterygoid muscle (LPM) and temporomandibular joint (TMJ) disc before and after Le Fort I osteotomy with and without intentional pterygoid plate fracture and sagittal split ramus osteotomy (SSRO) in class II and class III patients. Le Fort I osteotomy and SSRO were performed in class II and class III patients. LPM measurements using oblique sagittal computed tomography (CT) images and TMJ disc position using magnetic resonance imaging (MRI) were examined. Statistical comparisons were performed for the LPM and TMJ between class II and class III patients and between those with and without intentional pterygoid plate fracture in Le Fort I osteotomy. The subjects comprised 60 female patients (120 sides), with 30 diagnosed as class II and 30 as class III. Preoperatively, the width of the condylar attachment, width at eminence, length of the LPM, angle of the LPM, and square of the LPM were significantly smaller in the class II group than in the class III group (p < 0.05). After 1 year, the width of the condylar attachment, width at eminence, and angle of the LPM remained significantly smaller in the class II group than in the class III group (p < 0.0001). TMJ disc position was significantly related to the width of the condylar attachment of the LPM, both pre- and postoperatively (p < 0.0001). However, postoperative disc position did not change in all patients. Next, the class II patients (60 sides) were divided into two groups who underwent Le Fort I osteotomy with or without intentional pterygoid plate fracture. Changes in all measurements of the LPM showed no significant differences between these two groups. Our study suggested that TMJ disc position classification could be associated with the width of condylar attachment of the LPM before and after surgery, while the surgical procedure, including Le Fort I osteotomy with intentional pterygoid plate fracture, might not affect postoperative LMP or disc position in class II patients.

Is the Temporomandibular Joints' Reciprocal Clicking Related to the Morphology and Position of the Mandible, as Well as to the Sagittal Position of Lower Incisors?-A Case-Control Study

The number of patients diagnosed with temporomandibular joint (TMJ) internal derangements, who are seeking orthodontic treatment, is increasing. The aim of the study was to assess the relationship between the presence of TMJ reciprocal clicking and the morphology and position of the mandible, and position of lower incisors, examined on the lateral cephalograms. Fifty patients diagnosed with reciprocal clicking in at least one of the TMJs and 55 patients with no symptoms of TMJ dysfunction were included in the study. Cephalometric analysis was used for the assessment of: skeletal class, sagittal and vertical position of the mandible, angle of the mandible, inclination of the mandibular ramus and the mandibular corpus, as well as for the assessment of the position of the mandibular incisors. The statistical significance level was set at p = 0.05. There were no statistically significant differences between the examined groups regarding the sagittal and vertical position of the mandible, as well as regarding the sagittal position of the mandibular incisors. Presence of TMJ reciprocal clicking is not associated with the position and the morphology of the mandible, as well as with the sagittal position of the mandibular incisors. Patients with early stages of TMJ internal derangements do not present any significant changes in Cephalometrics. Patients diagnosed with TMJ internal derangements before orthodontic treatment require an interdisciplinary approach to the treatment, including physiotherapy.

Relationship between rotational disc displacement of the temporomandibular joint and the dentoskeletal morphology

Objective

The purpose of this study was to evaluate the relationship between rotational disk displacement (DD) of the temporomandibular joint (TMJ) and the dentoskeletal morphology.

Methods

Women aged > 17 years were included in this study. Each subject had a primary complaint of malocclusion and underwent routine cephalometric examinations. They were divided into five groups according to the findings on sagittal and coronal magnetic resonance images of their TMJs bilateral normal disk position, bilateral anterior DD with reduction (ADDR), bilateral rotational DD with reduction (RDDR), bilateral anterior DD without reduction (ADDNR), and bilateral rotational DD without reduction (RDDNR). Twenty-three cephalometric variables were analyzed, and the Kruskal–Wallis test was used to evaluate differences in the dentoskeletal morphology among the five groups.

Results

Patients with TMJ DD exhibited a hyperdivergent pattern with a retrognathic mandible, unlike those with a normal disk position. These specific skeletal characteristics were more severe in patients exhibiting DD without reduction than in those with reduction, regardless of the presence of rotational DD. Rotational DD significantly influenced horizontal and vertical skeletal patterns only in the stage of DD with reduction, and the mandible exhibited a more backward position and rotation in patients with RDDR than in those with ADDR. However, there were no significant dentoskeletal differences between ADDNR and RDDNR.

Conclusions

The results of this study suggest that rotational DD of TMJ plays an important role in the dentoskeletal morphology, particularly in patients showing DD with reduction.

Association between degenerative temporomandibular joint disorders, vertical facial growth, and airway dimension

BACKGROUND

The goal of this study was to determine whether preexisting degenerative temporomandibular joint (TMJ) disorders are associated with hyperdivergent facial phenotype and decreased airway dimensions.

METHODS

Cone-beam computed tomography scans of adult female and male individuals, 16 years of age and older, distributed in a case group defined as those with degenerative temporomandibular joint disorder (dTMJD; n = 31) or controls with normal TMJ findings (n = 242) were included. Odds ratios were calculated based on facial type and gender. Analysis of variance was used to compare the airway volume and cross section and mandibular measurements between the groups.

RESULTS

Condylar, ramus, and mandibular heights were significantly smaller in the case group compared with the control group. The odds of having a long face subject was significantly higher (P < 0.00001) in the dTMJD group than in the control group with 81% of the dTMJD subjects versus 11% of the control group having long vertical facial dimensions. The smallest cross-sectional area of the airway of the dTMJD group was significantly narrower (P < 0.0361) compared with the controls. Within the control group, ramus height and mandibular alveolar housing for central incisors were significantly smaller (P < 0.0001; P < 0.007) in the long face subjects.

CONCLUSIONS

The study shows that a long facial type is associated with findings of degenerative TMJ disorders and related condylar growth disturbances. These degenerative and growth changes may contribute to specific skeletal and dentofacial adaptations resulting in smaller condylar process, mandibular ramus, and body height; thinner alveolar housing at the lower incisor region; and smaller cross-sectional area of the airway.

The relation of cephalometric features to internal derangements of the temporomandibular joint: A systematic review and meta-analysis of observational studies

PURPOSE

To review and summarize the data on the relationship between craniofacial morphology features and internal derangement (ID) of the temporomandibular joint (TMJ).

METHOD

A systematic review was designed and registered at PROSPERO, CRD42019132731. The PubMed, Embase and Scopus databases were searched for cephalometric studies comparing craniofacial morphology between female patients with TMJ ID and controls. The Newcastle-Ottawa Scale (NOS) was used for quality assessment. Weighted mean differences for cephalometric measurements were pooled for subsequent meta-analysis.

RESULT

From the establishment date to August 2020, 14 of 1038 collected records were selected, which consisted of 772 patients with TMJ ID and 423 controls. These records were eventually pooled for the designed statistical analysis after the NOS quality assessment. Compared with the controls, TMJ ID patients had obviously smaller, retruded and clockwise-rotated mandible, showing significantly decreased S-Na, S-Go, Go-Me, Ar-Pog, Ar-Go, SNB, Na perp Pog, and increased FH-MP, SN-MP, PP-MP, SN to Ar-Go, S-Ar-Go and ANB.

CONCLUSION

Certain craniofacial morphology features were found strongly associated with the presence of TMJ ID, especially the size and position of the mandible.

Relations between anterior disc displacement and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle

In this study we investigated the relation between anterior disc displacement (ADD) and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle. Thirty female patients (60 joints) with both conditions were evaluated. Magnetic resonance imaging of the temporomandibular joint (TMJ) was used to diagnose both ADD and changes to the mandibular condyle (erosion, osteophyte, and deformity). The relations among ADD, changes to the mandibular condyle, and maxillomandibular morphology were examined statistically. Changes to the mandibular condyle had a higher score than sym anterior open bite, the deviated side in asymmetric anterior open bite, and the non-deviated side. The score for disc displacement on the non-deviated side was lower than both the sym side and the deviated side. Unilateral changes to the mandibular condyle and unilateral disc displacement were not apparent in sym anterior open bite, but a unilateral non-displaced disc was seen only on the asymmetric side. Mandibular condylar changes were significantly more common on the deviated, than on the non-deviated, side. The SNB angle was significantly smaller, and the ANB, GZN, and SN-mandibular plane angles were significantly larger in sym anterior open bite. Overjet, ANB angle, GZN angle, and SN-MP angle were significantly larger, and the SNB angle was significantly smaller, in the presence of ADD without reduction and mandibular condylar deformity. We conclude that the prevalence of ADD without reduction and changes to the mandibular condyle were related to mandibular asymmetry and mandibular morphology in anterior open bite. This retrospective study suggests that ADD without reduction and mandibular condylar bone changes may be related to the progression of skeletal class II open bite and mandibular asymmetry in cases of skeletal open bite.

Does TMJ Function and Imaging Tools Help Differentiate Between Condylar Resorption and Mandibular Hypoplasia?

PURPOSE

Differentiating between bilateral condylar resorption (CR) and mandibular hypoplasia (MH) can be challenging owing to the difficulty in chronological observation and establishing standardized measurements. The purpose of the present study was to assess whether temporomandibular joint (TMJ) function can distinguish between CR and MH and clarify the essential diagnostic imaging tools for CR.

MATERIALS AND METHODS

We performed a cross-sectional study of patients with mandibular retrognathia. The primary predictor variables were a clinical dysfunction score for the TMJ, mandibular plane angle (MPA), SNA angle, SNB angle, and cortical erosion score in the condylar heads. The demographic variables were age, anterior disc displacement, and previous orthodontic treatment. The anatomic variable was the condylar height (CH). The primary outcome variable was the disease status (CR or MH). The patients were divided into the CR group and MH group. The patients with CR were selected on the basis of a CH value of less than 22 mm. TMJ function was assessed using the Helkimo clinical dysfunction index. The CH on panoramic radiographs was measured using the Kjellberg method. The MPA, SNA angle, and SNB angle were analyzed using cephalometric analysis. Cortical erosion in the condylar head was assessed using computed tomography and magnetic resonance imaging.

RESULTS

A total of 23 female participants were enrolled in the present study. The average clinical dysfunction score for the TMJ was 4.4 in the CR group and 0.4 in the MH group (P < .05). The average MPA was 41.2° in the CR group and 35.5° in the MH group (P < .05).

CONCLUSIONS

The present investigation has shown that assessing TMJ function and analyzing MPA using a cephalometric radiograph can differentiate CR from MH.

The study of facial morphology in patients with vertical growth pattern (hyperdivergent) lacking or showing temporomandibular disorders symptoms

AIM

According to the large number of studies, there seems to be a significant relation between hyperdivergence growth pattern and temporomandibular disorders. However, it is not clearly scrutinized which morphological factors can contribute to the development of temporomandibular disorders. The aim of this study was to investigate the relation between some skeletal and facial morphologic features of hyperdivergent facial growth pattern patients and temporomandibular disorders.

MATERIALS AND METHODS

This case-control study was performed on a population of 50 patients including 25 patients with temporomandibular disorder and 25 non- temporomandibular disorder individuals aged between 15-30 years with hyperdivergent growth pattern (Frankfurt Mandibualr plane angle between 28 and 35 degree). Two groups of symptomatic and asymptomatic patients (case and control) were matched for age and gender. In order to evaluate the skeletal and dental variables, lateral cephalometries was taken and traced after obtaining written consent from the patients. The measured variables were A point to Nasion to B point, Frankfurt plane to Nasion to Pogonion, Nasion to A point to Pogonion, Sella to Gnathion to Frankfurt plan, Articular point to Gonion-Menton, Sella to Articular point to Gonion, Palatal plane to Mandibular plane, and Articular point to Gonion angles. The intervals of Basion to Nasion, Sella to Basion, Gonion to Menton, and amounts of Anterior facial height meas, Upper Anterior facial height ratio to Lower Anterior facial height, posterior facial height, overjet, and overbite Data were analyzed by Chi² test, t-test, and multivariate test.

RESULTS

According to the descriptive statistics, the age of the control and case groups averaged 21.12±1.99 and 21.63±1.58 years respectively. Among the people referred to the dental school, the frequency of males and females in the control and case groups were 6, 7 and 19, 18 respectively. The results of t-test and multivariate tests indicated significant differences between the two variables of overbite and mandibular length.

CONCLUSION

The present study revealed increased overbite (dental feature) and mandibular length (skeletal feature) is more likely to be associated with a higher risk of temporomandibular disorders joint disease in patients with hyperdivergent facial growth pattern.

CLINICAL SIGNIFICANCE

Treatment of the deep bite condition can be helpful in improving temporomandibular disorder.

Changes of temporomandibular joint position after surgery first orthognathic treatment concept

Orthognathic surgery treatment (OGS) after orthodontic treatment of dentofacial deformities is a widely performed procedure, often accompanied by a bilateral sagittal split osteotomy (BSSO). Positioning of the condyle during this procedure is a crucial step for achieving optimal functional and anatomical results. Intraoperatively poorly positioned condyles can have a negative effect on the postoperative result and the patient’s well-being. Changes of the condylar position during OGS Procedures and its effects on the temporomandibular joint in orthognathic surgical interventions (OGS) are subject of scientific discussions. However, up to date, no study has investigated the role of condyle position in the surgery first treatment concept. The aim of this study was to investigate the influence of OGS on the three-dimensional position of the condyle in the joint in a surgery first treatment concept without positioning device and to record the change in position quantitatively and qualitatively. Analysis of our data indicated that OGS in surgery first treatment concept has no significant effect on the position of the condyle and the anatomy of the temporomandibular joint.

Relationships between temporomandibular joint disk displacements and condylar volume

OBJECTIVES

The aim of this study was to assess the relationship between mandibular condylar volume and disk displacement status in adult males and females.

STUDY DESIGN

We evaluated 122 temporomandibular joints in 61 patients using magnetic resonance imaging (MRI) and computed tomography (CT). MRI data were used to assign disk status as normal disk position (NR), disk displacement with reduction (DDR), or disk displacement without reduction (DDNR). CT data were used to calculate total condylar volume and its components, cortical volume, and trabecular volume. The relationships among condylar volume, disk status, and gender were tested with 2-way analysis of variance.

RESULTS

Condylar volumes significantly correlated with disk displacement, tending to decrease as displacement increased. There were significant differences in both total condylar volume and trabecular volume among the DD status (NR > DDR > DDNR), whereas cortical volume was significantly different only between NR/DDR and DDNR (NR/DDR > DDNR). The volume decreases associated with temporomandibular joint DD were found in both males and females, with greater decreases in men than in women as DD progressed.

CONCLUSIONS

Condylar volumes are significantly associated with disk displacement status. Joints with nonreducing disks showed the smallest condylar volumes in both males and females.

Cranial morphology in the brachygnathic sheep

Background

Craniofacial morphology of sheep with phenotypically observed mandibular distocclusion was analysed using the multivariate techniques principle component analysis and cluster analysis in order to test whether different types of craniofacial malformations can be distinguished.

Results

The results showed 8 principal components with a variance of 82.72 % in the database. The method creates new variables then used in the Cluster analysis indicating 7 clusters with 3 different facial types: Normal, prognathia inferior and brachygnathia inferior.

Conclusion

The brachygnathic facial type was mainly characterised as a shortened mandible, the upper jaw is not significantly involved. The correlations to the temporomandibular joint were shown. Molar and premolar malocclusions were revealed in two of three Clusters. Phenotypical distocclusion was not a single criterion for the affected sheep.

Cephalometric Analysis of the Facial Skeletal Morphology of Female Patients Exhibiting Skeletal Class II Deformity with and without Temporomandibular Joint Osteoarthrosis

Purpose

This study evaluated the differences in the facial morphological characteristics of female patients exhibiting skeletal class II deformity with and without temporomandibular joint osteoarthrosis.

Methods

Eighty-three female patients with skeletal class II deformity were included in this study; these patients were classified into three groups on the basis of the condylar features shown in cone-beam computed tomography scans: normal group, indeterminate for osteoarthrosis group, and osteoarthrosis group. The cephalometric differences among the three groups were evaluated through one-way ANOVA.

Results

Of the 83 patients, 52.4% were diagnosed with osteoarthrosis, as indicated by the changes in the condylar osseous component. The cephalometric measurements that represented skeletal characteristics, including mandibular position relative to the cranial base, mandibular plane angle (MP-SN), posterior facial height (S-Go), and facial height ratio, were significantly different among the three groups (p < 0.05). The patients in the osteoarthrosis group yielded the smallest S-Go, the highest MP-SN, and the most retruded mandible.

Conclusions

Temporomandibular joint osteoarthrosis is commonly observed in female patients with skeletal class II deformity. The morphological characteristics of the facial skeleton in patients with bilateral condylar osteoarthrosis may be altered.

The relevance analysis of hyoid bone position to skeletal or dental openbite and dentofacial characteristics

OBJECTIVE

The aim of this study was to investigate the relationship between the hyoid bone position and skeletal or dental openbite and to investigate dentofacial characteristics as indicated by the hyoid bone position.

STUDY DESIGN

In our study, 182 patients were included on the basis of skeletal and dental openbite. The hyoid bone position of the subjects was compared and evaluated. In addition, by dividing the samples according to the hyoid bone position, dentofacial characteristics of the subjects were compared and analyzed.

RESULTS

There were significant differences in the hyoid bone position according to the skeletal pattern, not dental pattern. The skeletal openbite group showed low hyoid bone position. In addition, the low hyoid bone group showed short ramus height, short posterior facial height, retrusive chin, and clockwise-rotated mandible.

CONCLUSIONS

Patients with low hyoid bone had a tendency toward skeletal openbite, even though there was no dental openbite. Moreover, low hyoid bone position had relevance to retrognathic dentofacial characteristics.

Orthognathic surgery and temporomandibular joint symptoms

The aim of this article is to review temporomandibular joint symptoms as well as the effects of orthognathic surgery(OGS) on temporomandibular joint(TMJ). The causes of temporomandibular joint disease(TMD) are multifactorial, and the symptoms of TMD manifest as a limited range of motion of mandible, pain in masticatory muscles and TMJ, Joint noise (clicking, popping, or crepitus), myofascial pain, and other functional limitations. Treatment must be started based on the proper diagnosis, and almost symptoms could be subsided by reversible options. Minimally invasive options and open arthroplasty are also available following reversible treatment when indicated.

TMD manifesting in a variety of symptoms, also can apply abnormal stress to mandibular condyles and affect its growth pattern of mandible. Thus, adaptive developmental changes on mandibular condyles and post-developmental degenerative changes of mandibular condyles can create alteration on facial skeleton and occlusion. The changes of facial skeleton in DFD patients following OGS have an impact on TMJ, masticatory musculature, and surrounding soft tissues, and the changes of TMJ symptoms. Maxillofacial surgeons must remind that any surgical procedures involving mandibular osteotomy can directly affect TMJ symptoms, thus pre-existing TMJ symptoms and diagnoses should be considered prior to treatment planning and OGS.

Factors related to the incidence of anterior disc displacement without reduction and bony changes of the temporomandibular joint in patients with anterior open bite

PURPOSE

We aimed to investigate factors related to the prevalence of anterior disc displacement without reduction (ADDwoR) and bony changes of the condylar head (bony changes) in the temporomandibular joints (TMJs) of patients with anterior open bite.

METHODS

Subjects are comprised of 36 preoperative patients (72 joints) with skeletal anterior open bite without facial asymmetry who had undergone orthognathic surgery at the Hokkaido University Hospital; magnetic resonance imaging of the TMJ and cephalometric analysis were performed before treatment. Logistic regression analysis was performed to clarify relationships among age, overbite, overjet, ANB angle, sella to nasion (SN) to mandibular plane angle (SN-MP angle), SN to ramus plane angle (GZN angle), gonial angle, and incidence of ADDwoR or bony changes in patients with anterior open bite.

RESULTS

Fifteen patients had bilateral ADDwoR, and five patients had unilateral ADDwoR; 17 patients had bilateral bony changes, and five patients had unilateral bony changes. SN-MP angle was greater in 20 patients with ADDwoR than that in 16 patients without ADDwoR (p < 0.05). GZN angle was greater in the 20 patients showing bony changes than that in the 16 patients without bony changes (p < 0.05).

CONCLUSION

In terms of dentofacial morphology, SN-MP angle appears to be associated with the incidence of ADDwoR, and GZN angle appears to be associated with bony changes in the TMJ.

Magnetic resonance imaging-verified temporomandibular joint disk displacement in relation to sagittal and vertical jaw deformities

This retrospective study was designed to analyze the relationships between temporomandibular joint (TMJ) disk displacement and skeletal deformities in orthodontic patients. Subjects consisted of 460 adult patients. Before treatment, lateral cephalograms and TMJ magnetic resonance imaging (MRI) were recorded. Subjects were divided into six groups based on TMJ MRI according to increasing severity of TMJ disk displacement, in the following order: bilateral normal TMJs, unilateral disk displacement with reduction (DDR) and contralateral normal, bilateral DDR, unilateral disk displacement without reduction (DDNR) and contralateral normal, unilateral DDR and contralateral DDNR, and bilateral DDNR. Subjects were subdivided sagittally into skeletal Class I, II, and III deformities based on the ANB (point A, nasion, point B) angle and subdivided vertically into hypodivergent, normodivergent, and hyperdivergent deformities based on the facial height ratio. Linear trends between severity of TMJ disk displacement and sagittal or vertical deformities were analyzed by Cochran-Mantel-Haenszel test. The severity of TMJ disk displacement increased as the sagittal skeletal classification changed from skeletal Class III to skeletal Class II and the vertical skeletal classification changed from hypodivergent to hyperdivergent. There were no significant differences in the linear trend of TMJ disk displacement severity between the sexes according to the skeletal deformities. This study suggests that subjects with skeletal Class II and/or hyperdivergent deformities have a high possibility of severe TMJ disk displacement, regardless of sex.

Gender differences in dentofacial characteristics of adult patients with temporomandibular disc displacement

PURPOSE

The purpose of this study was to assess gender differences in dentofacial characteristics of adult patients according to temporomandibular joint (TMJ) disc displacement (DD) status.

MATERIALS AND METHODS

The sample consisted of 293 adult patients (80 male and 213 female). Male and female patients were divided into 3 groups based on magnetic resonance images of bilateral TMJs: bilateral normal disc position (BN), bilateral DD with reduction (DDR), and bilateral DD without reduction (DDNR). Seventeen variables from lateral cephalograms were analyzed by 2-way analysis of variance to identify differences in dentofacial morphologies with respect to gender and TMJ DD status.

RESULTS

Patients with TMJ DD had short ramus height, short mandibular body length, and backward positioning of the ramus and mandible. These dentofacial characteristics became more severe as TMJ DD progressed to DDNR. In addition, dentofacial characteristics associated with TMJ DD were not significantly different between men and women except for effective mandibular length (Articulare to pogonion). Effective mandibular length even tended to decrease as TMJ DD progressed, but male patients showed a larger difference in effective mandibular length between BN and DDR than female patients.

CONCLUSIONS

This study's findings suggest that dentofacial morphology is strongly associated with TMJ DD status and that skeletal Class II hyperdivergent pattern with a short ramus and mandible may be a potential indicator of TMJ DD regardless of gender.

Ovine craniofacial malformation: a morphometrical study

Craniofacial malformation in 64 sheep was phenotypically described as mandibular distoclusion. Digital radiographs were examined in order to determine the degree of morphological changes in certain bones of the skull. Therefore, laterolateral standardised digital radiographs were used to determine anatomic reference points. Subsequently, five reference lines were defined and 16 linear and seven angular measurements were determined to describe malformations in the bones of the skull. Statistical analysis revealed a significant shortening of the rostral part of the corpus mandibulae and of the ramus mandibulae. However, the molar part of the mandible remained unchanged. These morphological changes caused premolar and molar malocclusion. No further craniofacial abnormalities, such as an elongation of the maxilla or of the incisive bone, were identified. In conclusion, the phenotypically observed mandibular distoclusion is caused by a shortening of specific parts of the mandible. This form of ovine craniofacial malformation is therefore best described as brachygnathia inferior.

Skeletal differences in patients with temporomandibular joint disc displacement according to sagittal jaw relationship

PURPOSE

The present study was designed to analyze the skeletal differences in patients with temporomandibular joint (TMJ) disc displacement (DD), according to the sagittal jaw relationship.

MATERIALS AND METHODS

We implemented a cross-sectional study design and enrolled a sample of Korean women older than age 17 years. The subjects were classified into 3 groups according to the magnetic resonance images of the bilateral TMJs: bilateral normal disc position (BN), bilateral disc displacement with reduction, and bilateral disc displacement without reduction. Each group was subdivided into 2 groups using the mandibular body length to anterior cranial base ratio as a sagittal jaw parameter: normal-size mandible (NM) and oversized mandible (OM). Seventeen variables from the lateral cephalograms were analyzed using 2-way analysis of variance to analyze the differences in skeletal characteristics with respect to the mandible size and TMJ DD status.

RESULTS

The subjects with TMJ DD generally had a short ramus height and clockwise rotation of the ramus and mandible compared with those with BN in both OM and NM groups. However, significant differences were present in the skeletal characteristics of the TMJ DD patients between the NM and OM groups. Significant backward positioning and rotation of the ramus and mandible were found between BN and bilateral disc displacement with reduction or bilateral disc displacement without reduction in the OM group, while those of the ramus and mandible were found between BN and bilateral disc displacement with reduction or bilateral disc displacement without reduction in the NM group.

CONCLUSIONS

The results of our study suggest that the skeletal characteristics associated with TMJ DD are differently represented according to the sagittal jaw relationship.

Lateral cephalometric analysis of mandibular morphology: discrimination among subjects with and without temporomandibular joint disk displacement and osteoarthrosis

To assess whether in patients with temporomandibular joint (TMJ) arthralgia cephalometric variables of mandibular morphology may discriminate among the magnetic resonance (MR) imaging-based TMJ groups of 'bilateral presence of disk displacement without reduction (DDwoR) and osteoarthrosis (OA)' and 'bilateral absence of bilateral DDwoR and OA'. Bilateral MR imaging of the TMJ was performed in 45 consecutive TMJ arthralgia patients to identify individuals with the specific structural characteristics of bilateral TMJ DDwoR associated with OA. Linear and angular cephalometric measurements were taken from lateral cephalograms to apply selected criteria of mandibular morphology. A discriminant function analysis was used to investigate how cephalometric parameters discriminate among the TMJ groups of 'bilateral presence of DDwoR with OA' and 'bilateral absence of DDwoR and OA'. Ramus height (Ar-Go) and effective mandibular length (Ar-Pog) produced a significant discriminant function that predicted TMJ group membership (P < 0·001). This function correctly classified 80·2% of original and cross-validated grouped cases. This study supports the concept that cephalometric variables of mandibular morphology discriminate among subjects with and without bilateral TMJ DDwoR and OA.

Cephalometric variables discriminate among magnetic resonance imaging-based structural characteristic groups of the temporomandibular joint

OBJECTIVE

The aim of this study was to assess retrospectively whether, in patients with temporomandibular joint (TMJ) arthralgia, commonly used cephalometric variables of dentofacial morphology can discriminate among magnetic resonanace imaging (MRI)-based TMJ structural characteristic groups of "uni- or bilateral disc displacement without reduction (DDwoR) associated with bilateral osteoarthrosis (OA)" and "uni- or bilateral disc displacement with reduction (DDwR) without OA."

STUDY DESIGN

Bilateral MRI of the TMJ was performed in 56 consecutive TMJ arthralgia patients to identify individuals with specific structural characteristic of uni- or bilateral TMJ DDwoR, DDwR, and OA. Application of the criteria resulted in a study group of 31 patients with "uni- or bilateral DDwoR with bilateral OA" and 25 with "uni- or bilateral DDwR without OA." Linear and angular cephalometric measurements were taken from lateral cephalograms to apply selected criteria of dentofacial morphology. One-way analysis of variance was used to assess differences in cephalometric variables by MRI-based TMJ group. Then, discriminant function analysis predicted TMJ group membership.

RESULTS

A-B plane to facial plane angle, palatal plane to occlual plane, and interincisal angle produced a significantly discriminant function that predicted TMJ group membership (P < .001). This function correctly classified 85.7% of original grouped cases.

CONCLUSIONS

Cephalometric variables may discriminate among MRI-based TMJ structural characteristic groups. Additional diagnostic information related to MRI-based classification groups was generated.

Structural characteristics of bilateral temporomandibular joint disc displacement without reduction and osteoarthrosis are important determinants of horizontal mandibular and vertical ramus deficiency: a magnetic resonance imaging study

PURPOSE

To estimate in patients with temporomandibular joint (TMJ) arthralgia whether magnetic resonance (MR) imaging findings of bilateral TMJ disc displacement without reduction (DDwoR) and/or osteoarthrosis (OA) are determinants of horizontal mandibular and vertical ramus deficiencies.

PATIENTS AND METHODS

Bilateral MR imaging of the TMJ was performed in 68 consecutive patients with TMJ arthralgia to identify those with bilateral TMJ DDwoR and/or OA. Linear and angular cephalometric measurements were performed to apply selected criteria of horizontal mandibular (gonion-menton [Go-Me] <73 mm and articulare-pogonion [Ar-Pog] <105 mm) and vertical ramus (articulare-gonion [Ar-Go] <45 mm) deficiencies. Logistic regression analysis was used to estimate the association between selected MR imaging and cephalometric parameters.

RESULTS

In the age- and gender-adjusted analysis, significant increases in the risk of horizontal mandibular (odds ratio, 7.5:1; P = .031) and vertical ramus (odds ratio, 9.5:1; P = .003) deficiencies occurred with bilateral DDwoR and OA.

CONCLUSION

In patients with TMJ arthralgia, the MR imaging parameters of DDwoR and OA seem important determinants of horizontal mandibular and vertical ramus deficiencies.

Dentofacial characteristics of women with oversized mandible and temporomandibular joint internal derangement

INTRODUCTION

To analyze dentofacial characteristics of temporomandibular joint internal derangement (TMJ ID) in orthodontic patients with oversized mandible (skeletal Class III pattern).

MATERIALS AND METHODS

The sample consisted of 66 women whose mandibular body length to anterior cranial base ratio is greater than 1.12. They were divided into three groups based on magnetic resonance images of bilateral TMJs: bilateral normal disk position (BN), bilateral disk displacement with reduction (DDR), and bilateral disk displacement without reduction (DDNR). Thirty-five cephalometric variables regarding their lateral cephalograms were analyzed by Kruskal-Wallis test to evaluate differences in dentofacial morphology among the three groups.

RESULTS

Subjects with TMJ ID had a clockwise rotation of the ramus, with backward position of mandible, labial tipping of mandibular incisors, and protrusion of upper and lower lips. However, TMJ ID did not significantly influence vertical skeletal relationships. Most of the significant dentofacial changes were found between BN and DDR, and dentofacial changes between DDR and DDNR were minimal.

CONCLUSIONS

This study suggests that dentofacial changes associated with TMJ ID begin to appear when TMJ ID develops to DDR from BN in patients with oversized mandible.

Surgical cephalometrics: applications and developments

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Describe the historical origins of modern cephalometry. 2. Identify common landmark points on the lateral cephalogram. 3. Describe multiple common clinical uses for cephalometry. 4. Exhibit knowledge of developments in imaging and analysis alternatives.

BACKGROUND

Interest in the dimensions of the human head has been present since antiquity. Proportional analysis and measures from cadaveric specimens led to the development of radiologic image capture and analysis on living subjects. These techniques were originally applied to establishing normative values, documenting growth, and diagnosing dentofacial disharmonies. This article reviews the origins of cephalometric methodology and current developments and applications.

METHODS

The authors conducted a MEDLINE search and review of all English language articles using the keywords "cephalometric" and "cephalometrics."

RESULTS

Cephalometrics have undergone substantial use and development since the introduction of radiologic imaging on living human subjects in 1931. Although frequently associated with orthognathic surgery, cephalometrics have been applied to a number of conditions involving altered craniofacial morphology. Advances in imaging and computing have led to increased interest in three-dimensional and non-x-ray-based assessment of the human head. Mathematical models have been applied to standard cephalometric information to increase the descriptive accuracy of the complex shapes involved.

CONCLUSIONS

Cephalometric techniques and analyses are versatile tools that can be applied to a wide variety of clinical scenarios involving the craniofacial region. New technologies and expanded applications promise to continue the development and use of this well-established methodology.

Influence of unilateral disc displacement on the stress response of the temporomandibular joint discs during opening and mastication

The temporomandibular joint plays a crucial role in human mastication acting as a guide of jaw movements. During these movements, the joint is subjected to loads which cause stresses and deformations in its cartilaginous structures. A perfect balance between the two sides of the joint is essential to maintain the physiological stress level within the tissues. Therefore, it has been suggested that a derangement of the joint is a contributing factor in the development of mandibular asymmetry, especially if problems of the temporomandibular joint start in childhood or adolescence. To analyze the movement of the mandible and the stresses undergone by the discs, two finite element models of the human temporomandibular joint including the masticatory system were developed, one corresponding to a healthy joint and the other with a unilateral anterior disc displacement with their movement controlled by muscle activation. A fibre-reinforced porohyperelastic model was used to simulate the behaviour of the articular discs. The stress distribution was analyzed in both models during free opening and closing, and during the introduction of a resistant force between incisors or molars. It was found that a slight unilateral anterior disc displacement does not lead to mandibular asymmetry but to a slight decrease of the maximum gape. With the introduction of a restriction between incisors, the maximum stresses moved to the anterior band in contrast to what happened if the restriction was imposed between molars where maximum stresses were located more posteriorly. Finally, the presence of a unilateral displacement of the disc involved a strong change in the overall behaviour of the joint including also the healthy side, where the maximum stresses moved to the posterior part.

Orthodontic Effects on Dentofacial Morphology in Women with Bilateral TMJ Disk Displacement

OBJECTIVE

To determine the difference in skeletal response to orthodontic treatment between patients with bilateral disk derangement and normal disk position of the temporomandibular joint (TMJ).

MATERIALS AND METHODS

Subjects consisted of 46 women whose malocclusions were treated only by orthodontics. All patients had TMJ magnetic resonance imaging (TMJ MRI) taken prior to orthodontic treatment. They were classified into three groups according to results of the TMJ MRI: bilateral normal disk position (BN), bilateral disk displacement with reduction (BDDR), and bilateral disk displacement without reduction (BDDNR). Twenty cephalometric variables were evaluated by the Kruskal-Wallis test to identify any differences in morphological changes between the three groups during orthodontic treatment.

RESULTS

This study showed that patients with BDDNR had more severe sagittal and vertical skeletal discrepancies than those with BN and BDDR at the pretreatment stage with discrepancies maintained after treatment. Compared to patients with BN, BDDR patients exhibited significant changes in SNB, N perpendicular to pogonion, SN to mandibular plane angle, total anterior facial height, ramus inclination, and effective mandibular length during treatment. This means that patients with BDDR showed more backward movement and rotation of the mandible than those with BN. In contrast, patients with BDDNR who had the most severe skeletal discrepancies did not show any significant skeletal changes during orthodontic treatment compared to those with BN or BDDR.

CONCLUSION

In patients with bilateral TMJ disk displacement, orthodontic treatment should be undertaken carefully to prevent backward rotation and movement of the mandible.

Discrimination of internal derangement of temporomandibular joint by lateral cephalometric analysis

INTRODUCTION

The purposes of this study were to analyze the progress of internal derangement (ID) of the temporomandibular joint (TMJ) and to find critical yardsticks that can be used during lateral cephalometric analysis to identify subjects with potential ID.

METHODS

The sample consisted of 134 women whose primary complaints were malocclusions. They were divided into 5 groups based on the results of magnetic resonance imaging of bilateral TMJs: bilateral normal disc position, unilateral disc displacement with reduction (DDR) and contralateral normal disc position, bilateral DDR, unilateral DDR and contralateral disc displacement without reduction (DDNR), and bilateral DDNR. Thirty-six cephalometric variables from their lateral cephalograms were analyzed with 1-way ANOVA and discriminant analysis to determine the key factors in identifying subjects with TMJ ID.

RESULTS

Backward positioning of the mandible, clockwise rotation of the mandible, proclination of the mandibular incisors, and increase in overjet intensified gradually with the progression of TMJ ID, and the subjects with bilateral DDNR showed the greatest changes in dentofacial morphology. Stepwise variable selection in discriminant analysis identified the following 2 variables: mandibular incisor to Frankfort horizontal plane angle and overjet. Discriminant analysis resulted in the correct classification of 79.1% of the subjects and showed that those with smaller mandibular incisor to Frankfort horizontal plane angles and larger overjets had high possibilities of TMJ ID.

CONCLUSIONS

This study suggests that some cephalometric variables can be used as an auxiliary diagnostic tool to help identify patients with potential TMJ ID.

Relationship between temporomandibular joint internal derangement and facial asymmetry in women

INTRODUCTION

Internal derangement (ID) of the temporomandibular joint (TMJ) can cause facial asymmetry. The purposes of this study were to analyze the relationship between facial asymmetry and TMJ ID by using posteroanterior cephalometric variables, and to compare the findings with the results of magnetic resonance imaging (MRI).

METHODS

The sample consisted of women seeking orthodontic treatment at Seoul National University Dental Hospital who had routine posteroanterior cephalograms and bilateral MRIs of the TMJ. To eliminate the influence of condylar hyperplasia on facial asymmetry, only those with SNB angles less then 78 degrees were selected (n = 63). They were classified into 5 groups according to the results of the MRI: bilateral normal disk position, unilateral normal TMJ and contralateral disk displacement with reduction (DDR), bilateral DDR, unilateral DDR and contralateral disk displacement without reduction (DDNR), and bilateral DDNR. Fourteen variables from posteroanterior cephalograms were analyzed with 1-way ANOVA to evaluate differences among the 5 groups.

RESULTS

Subjects with TMJ ID of greater severity on the unilateral side had shorter ramal height compared with those with bilateral normal or bilateral DDR or bilateral DDNR. In addition, the mandibular midpoint deviated toward the side where the TMJ ID was more advanced.

CONCLUSIONS

Subjects with a more degenerated TMJ on the unilateral side might have facial asymmetry that does not come from condylar or hemi-mandibular hyperplasia.

Estrogen receptor gene polymorphism and craniofacial morphology in female TMJ osteoarthritis patients

The aim of this study was to investigate the possible influence of estrogen receptor alpha (ERalpha) polymorphism on the craniofacial skeleton in female patients suffering from symptomatic osteoarthritis (OA) of the temporomandibular joint (TMJ). The sample comprised 76 genetically unrelated Korean women diagnosed with OA by research diagnostic criteria for temporomandibular disorders (RDC-TMD). Direct haplotyping procedure was used to analyze the PvuII and XbaI RFLPs. Twelve cephalometric measurements were taken to evaluate the spatial position and dimensions of the mandible. Mann-Whitney's U-test was used to identify the potential differences in the cephalometric measurements between the subjects grouped according to their carrier status for Px haplotype. In addition, an association study was carried out using chi(2)-test to further examine the relationship between Px haplotype and the craniofacial morphology of the symptomatic OA patients. Female symptomatic TMJ OA patients carrying Px haplotype showed significantly smaller facial axis angle (P<0.05) and mandibular body length (P<0.05) than the non-carriers. The association between the presence of Px haplotype and short mandibular body length was also ascertained. This study suggests that ERa polymorphism contributes to the altered mandibular dimensions in female symptomatic TMJ OA patients. Further studies on the role of the genetic markers relevant to the craniofacial growth and adaptation are expected to broaden our understanding of determinants of the craniofacial morphology.

Relationship between internal derangement of the temporomandibular joint and dentofacial morphology in women with anterior open bite

INTRODUCTION

Anterior open bite is known to be associated with internal derangement of the temporomandibular joint (TMJ). This study examined the relationships between internal derangement and dentofacial morphology in women with anterior open bite.

METHODS

Fifty-one women with anterior open bite were enrolled in this study. The sample was divided into 3 groups based on magnetic resonance imaging of bilateral TMJs: normal disk position, disk displacement with reduction, and disk displacement without reduction. One-way analysis of variance was used to compare the 3 groups with respect to the cephalometric variables, and Duncan's multiple comparisons were performed at the 95% confidence level to identify the differences among the 3 groups.

RESULTS

Internal derangement of the TMJ was much more prevalent in subjects with a more posteriorly rotated mandibular ramus, a smaller mandible, and a greater tendency for a skeletal Class II pattern, although all subjects had an anterior open bite. These patterns were more severe as the internal derangement progressed to disk displacement without reduction.

CONCLUSIONS

Some cephalometric characteristics, such as a decrease in posterior facial height, decrease in ramus height, and backward rotation and retruded position of the mandible, are associated with TMJ internal derangement in women with anterior open bite.