Menton Deviation Research Articles

Observational study investigating the relationship between maxillomandibular characteristics and temporomandibular disc conditions in female patients with a skeletal class III pattern.

The objective of this study was to analyze the relationship between maxillomandibular characteristics and the severity of temporomandibular disc displacement in female patients with a skeletal class III (SKIII) pattern. Fifty-seven samples were included in the study. The evaluation of articular disc conditions was conducted using magnetic resonance imaging, while 25 cephalometric variables from lateral and postero-anterior (P-A) cephalograms were measured to determine their maxillomandibular characteristics. The samples were categorized into three groups based on the articular disc conditions: (1) normal disc position (NDP), (2) disc displacement with reduction (DDwR), and (3) disc displacement without reduction (DDwoR). The relationship between the maxillomandibular characteristics and disc conditions was examined through both basic statistical analysis and multivariate analysis using principal component analysis (PCA). The Kruskal-Wallis and Dunn-Bonferroni tests revealed a significant difference between the groups in terms of the deviation of mandibular characteristics observed on the P-A cephalogram. The DDwoR group exhibited significantly larger menton deviation, ramal height asymmetry index, and total mandibular length asymmetry index compared to the NDP and DDwR groups. Moreover, the PCA successfully extracted all cephalometric variables into eight principal components. Among them, only the principal component related to mandibular asymmetry was able to differentiate the SKIII samples with DDwoR from the other groups. The findings of this study highlight a significant relationship between mandibular asymmetry and the severity of disc displacement, particularly DDwoR, in female patients with a SKIII pattern.

Three-dimensional characteristics of temporomandibular joint morphology and condylar movement in patients with mandibular asymmetry

BackgroundInvestigating the morphological and functional effects on mandibular asymmetry (MA) is important not only to understand the developmental process of masticatory dysfunction, but also to provide suggestions for evidence-based occlusal treatment. AimTo evaluate three-dimensional temporomandibular joint (TMJ) morphology and its relationship to asymmetrical condylar movement in MA patients.Materials and methodsFifty subjects were divided into MA and control groups (n = 25 each) according to a menton deviation of 4 mm from the mid-sagittal plane. TMJ morphology (condyle, glenoid fossa and TMJ spaces) were evaluated using a three-dimensional analysis programme. Three-dimensional condylar movements (from the sagittal and horizontal planes) were recorded and measured by computerized axiography on protrusion. Side-to-side asymmetry was measured for each parameter. The asymmetry index value was calculated to assess the correlation between TMJ morphology and condylar movement. For the statistical analysis, Wilcoxon’s signed-ranked test, the Mann–Whitney U test, and Spearman’s rank correlation were used.ResultsGlenoid fossa volume, surface area, anteroposterior length, and condylar volume were significantly smaller, and articular eminence angle, glenoid fossa, and condylar axial angle were significantly larger, on the shifted side of the MA group when compared with those on the non-shifted side and the mean values of the control group (P < 0.05). The TMJ spaces of the MA group showed no bilateral difference but were significantly narrower in the medial, superior, and anterior joint spaces when compared with the control group (P < 0.05). Condylar path length and sagittal condylar inclination were significantly asymmetrical. The asymmetry index of the condyle volume was significantly correlated with that of the condylar path length (P = 0.005). The asymmetry index of the glenoid fossa volume and the articular eminence angle were significantly correlated with that of the sagittal condylar inclination (P = 0.009 and P = 0.002, respectively), and the asymmetry index of glenoid fossa volume was significantly correlated with the bilateral transverse condylar inclination (P = 0.006 and P = 0.016, respectively).ConclusionsMorphological asymmetry of the TMJ is significantly different between the shifted and non-shifted sides and is closely related to functional asymmetry of condylar movement in MA patients. (350/350).

Three-dimensional quantitative analysis of dental and skeletal characteristics of skeletal Class I unilateral posterior crossbite in adults.

To study the dentoskeletal characteristics and the degree of compensations in skeletal Class I adults with unilateral posterior crossbite (UPCB). A sample of 40 adults was chosen for this cross-sectional study. 20 skeletal Class I adults with UPCB (mean age: 22.20±2.88years), were compared to 20 skeletal Class I adults with normal occlusion (mean age: 27.56 ± 5.76years). The respective dentoskeletal measurements were made on cross-sectional images from cone-beam computed tomography scans. Skeletally, both groups showed significant differences (P < 0.05) in mandibular corpus length and menton deviation with the UPCB group showing the greatest displacement. Maxillomandibular vertical asymmetry and condylar positional asymmetry were not significant in both groups (P > 0.05). For dental variables on the second premolar and first molar, the UPCB group showed greater linear and angular differences when compared to the control group (P < 0.05). On the crossbite side, maxillary posterior teeth were more buccally inclined, and mandibular posterior teeth were more lingually inclined. However, on the non-crossbite side, both maxillary and mandibular posterior teeth were lingually inclined. Adults with UPCB showed distinct transverse dentoskeletal asymmetry. No asymmetry was found in the condylar position and the mandibular height in UPCB adults.

Three-Dimensional Change of Lip after Two-Jaw Surgery in Facial Asymmetry Using Facial Scanner

A facial scanner and three-dimensional computed tomography (CT) were used to evaluate the three-dimensional change in lip asymmetry before and after two-jaw surgery for 22 patients with facial asymmetry (menton deviation &gt; 3 mm). We used the labrale superius (Ls), deviated/non-deviated-side cheilions (Ch-D/Ch-ND), and labrale inferius (Li) to construct the upper and lower lip planes to evaluate the lip asymmetry. A correlation analysis was performed to determine the factors related to the vertical change in the cheilions (ΔChZ-D/ND). In the transverse axis, Ch-D and Li moved to improve the asymmetry after surgery. All landmarks, except the Ls, moved backward in the anteroposterior axis. In the vertical axis, significant upward movement was observed in all hard tissue landmarks; however, there were no significant changes in the soft tissue. In the lip plane, the difference in the height of Ch-D and Ch-ND was significantly reduced (1.38 mm vs. 0.72 mm). In the anteroposterior axis, the ΔChZ-D/ND showed significant correlations with the mandibular setback. In the vertical axis, the ΔCh-ND showed significant correlations with the maxillary impaction of the non-deviated side. The improvement in lip asymmetry post-surgery was mainly achieved by the movement of the lower lip and Ch-D rather than the upper lip and Ch-ND.

The accuracy of a three-dimensional face model reconstructing method based on conventional clinical two-dimensional photos

BackgroundThis study aims to investigate the accuracy of a three-dimensional (3D) face reconstruction method based on conventional clinical two-dimensional (2D) photos.MethodsTwenty-three patients were included, and Character Creator v3.2 software with the Headshot v1.0 plugin was used for 3D face model reconstruction. Various facial landmarks were finely adjusted manually to refine the models. After preprocessing and repositioning, 3D deviation analysis was performed. The accuracy of the landmarks in different dimensions was determined, and twelve facial soft tissue measurements were compared to validate the clinical potential of the method.ResultThe reconstructed 3D face models showed good facial morphology with fine texture. The average root mean square errors between face scan models and reconstructed models at perioral area (1.26 ± 0.24 mm, 95%CI: 1.15–1.37 mm) were significantly smaller than the entire facial area (1.77 ± 0.23 mm, 95%CI:1.67–1.88 mm), P < 0.01. The deviation of menton of soft tissue was significantly larger than pronasale (P < 0.01). The deviations of all landmarks in the Y-direction were significantly larger than those in the other 2 dimensions (Y > Z > X, P < 0.01). A significant difference (P < 0.05) of approximately 1.5 mm was found for facial height. Significant differences (P < 0.05) were also identified in the remaining 6 soft tissue measurements, with average deviations no greater than 0.5 mm (linear measurement) or 1.2° (angular measurements).ConclusionA 3D face modeling method based on 2D face photos was revealed and validated. The reconstruction accuracy of this method is clinically acceptable for orthodontic measurement purposes, but narrow clinical indications and labor-intensive operations remain problems.

Three-dimensional mandibular characteristics in skeletal malocclusion : Across-sectional study.

We aimed to comprehensively analyse apossible correlation between skeletal malocclusions, gender and mandibular characteristics in all three dimensions in adults and to identify mandibular characteristics that are typical for extreme skeletal patterns. A3D model of the skull was calculated in 111 adult patients (mean age = 27.0 ± 10.2years; 49women, 62men) from available computed tomography or cone beam computed tomography scans of their heads. Based on the 3D models, the skeletal patterns were examined in (a)the transversal dimension regarding asymmetry according to menton deviation, (b)the sagittal dimension according to the Wits appraisal and (c)the vertical dimension according to the maxillomandibular plane angle. The mandibular characteristics assessed were linear (ramus height and width, body length), angular (ramus, gonial and body angle) and volumetric (ramus/mandibular volume, body/mandibular volume) parameters. No correlation between transversal skeletal asymmetry and mandibular characteristics were found, while sagittal (F(16, 174) = 3.32, p < 0.001, η2 = 0.23) and vertical (F(16, 174) = 3.18, p < 0.001, η2 = 0.23) skeletal patterns were shown to have asignificant effect on the mandible. Gender correlated with mandibular characteristics independently from the skeletal pattern. Discriminant analysis revealed that classII andIII patients differed in ramus and body angle with classII patients showing higher angles (ramus angle: class II = 89.8 ± 3.9° vs. class III = 84.4 ± 4.8°; body angle: class II = 87.7 ± 4.8° vs. class III = 82.1 ± 5.2°). Hypo- and hyperdivergent patients were discriminated by gonial angle, body angle and body/mandibular volume with hyperdivergent patients having agreater gonial and body angle and body/mandibular volume (gonial angle: hypodivergent = 114 ± 9.3° vs. hyperdivergent = 126.4 ± 8.6°; body angle: hypodivergent = 82.9 ± 4.4° vs. hyperdivergent = 87.7 ± 6.5°; body/mandibular volume: hypodivergent = 72.4 ± 2.7% vs. hyperdivergent = 76.2 ± 2.6%). When analysing 3D data for treatment planning of adult patients, the orthodontist should pay attention to angular and volumetric characteristics of the mandible to identify extreme skeletal sagittal or vertical malocclusions.

Influence of different treatment procedures on the temporomandibular joint after mandibular setback in skeletal class III - A retrospective study

The aim of this study was to clarify the effects of three different orthognathic surgical procedures on the temporomandibular joint after mandibular setback. Conventional sagittal split ramus osteotomy (SSRO) with segmental fixation (conv-SSRO), intraoral vertical ramus osteotomy (IVRO), or SSRO without fixation followed by the physiological positioning strategy (nonfix-SSRO) was performed for mandibular setback. Temporomandibular joint disorder (TMD) symptoms were clinically assessed, and the condylar head angle was measured. In total, 129 patients participated. Preoperative TMD and treatment procedure were related to postoperative TMD. A menton deviation of 3.43 mm was the cutoff for the risk of postoperative TMD. The incidence rate of postoperative TMD in the conv-SSRO group was higher than that in the IVRO (p = 0.0197) and nonfix-SSRO (p = 0.0001) groups in asymmetric cases. There was no significant postoperative change in the temporomandibular joint space in each group. In symmetric and asymmetric cases, the condylar head was rotated inwards by 5.82 ± 4.75° (p < 0.0001) and 5.44 ± 3.10° (p < 0.0001), respectively, in the conv-SSRO group, and outwards by −7.98 ± 5.05° (p < 0.0001) and −8.32 ± 6.38° (p < 0.0001), respectively, in the IVRO group, but it was almost stable in the nonfix-SSRO group. Within the limitations of the study it seems that nonfix-SSRO should be preferred over conv-SSRO and IVRO whenever appropriate.

Condylar and ramus volume in asymmetric and symmetric skeletal class III malocclusion: A cone-beam computed tomography study

Background/purposeAmong the craniofacial structures, the mandible is the only bony structure with movable joints. Each part (including condyle process, coronoid process, and ramus) of mandible would interaction with the muscles and proceed different osteogenesis progress. The objective of this study was to evaluate the mandibles with symmetric and asymmetric skeletal Class III jaw relations by quantifying differences in the condyle process, coronoid process and ramus on CBCT (Cone-beam computer tomography) images. Our hypothesis was that CBCT would reveal no voluminal differences between deviated and non-deviated mandibular segments in asymmetric skeletal Class III. Materials and methodsCBCT imagines were collected from dental department, KMUH and then divided into symmetric Class III group (Menton deviation < 4mm) and asymmetric Class III group (Menton deviation≧4mm). The mandibular structure would be segmented to ramus, condylar and coronoid process. Each volume was measured. Independent t test was used for comparison between groups, and paired t test was applied for comparison between both segmented parts within each group. ResultsSignificant differences between deviation and non-deviation sides in the asymmetric group were found in condylar and ramus segments for volumetric quantitative measurements. There has no significant difference in ramus parts between groups. Significant greater condylar volume was found in non-deviation side of asymmetric group. ConclusionThe results demonstrated that in the side with greater mandible growth potential, the condylar and the ramus volume would be greater as well. CBCT is a useful and accurate modality for quantification and evaluation of mandibular asymmetry.

A cone beam computed tomography study based on three-dimensional cephalometric analysis of relationships between the lip-line and jaw deformity

ObjectiveThe aim of this study was to use the cone beam computed tomography (CBCT) to study the relationships between the lip-line and mandible deformity. DesignCBCT data of 20 patients with jaw deformity (experimental group) and 20 patients without mandible deformity (control group) were selected. Use three-dimensional cephalometry to measure the reconstructed images of CBCT data simulated by the Materialise Interactive Medical Image Control System (Mimics), mark the related points, lines and planes of the three-dimensional craniomaxillofacial structure, and measure relevant distances and angles. The T-test, Pearson correlation analysis and Linear regression were used to analyze the characteristics of the lip-line and jaw deformity. ResultsThere was a significant difference in the lip-line between mandible deformity group and control group. Significant positive correlations could been found among the lip-line cant, the occlusal plane cant, the mandibular plane cant and the degree of mandible deformity (r=0.964, 0.942, 0.611, P < 0.01). A linear relationship was found between the left lip-line cant Y and the menton deviation X [the mandible deflection to the right was defined as positive, and the left lip-line below frankfort horizontal was viewed as positive] as Y= 0.340 + 0.505X. ConclusionsThe lip-line of patients with jaw deformity was inclined, and the lip-line cant was positively correlated with the degree of mandible deformity, and there was a certain linear relationship between the two, which could provide a theoretical reference for clinicians to diagnose and treat patients with mandible deformity.

Do Orthognathic Patients and Persons Without Facial Deformities Have Different Visual Attention to Menton Deviation?

This study aimed to quantify how menton deviation influenced facial visual attention of orthognathic patients and persons without facial deformities, and to explore differences between them. The visual scanning paths of 260 participants (Group I, 130 orthognathic participants; Group II, 130 participants without facial deformities) while observing images reflecting normal subjects and those with different menton deviation degrees were recorded with an eye-tracking device. The fixation duration [FD] and first fixation time [FFT]) on the areas of interest for each group were compared. Although Group I devoted longer FD to the lower face than the Group II when observing a normal face (P < 0.05), a menton deviation of 3°D was associated with a significantly longer FD and earlier FFT for both groups ( P < 0.05). As the severity of the menton deviation increased, this trend became more obvious, and the visual attention paid to the eyes and nose decreased (FD decreased, FFT delayed), especially for Group II ( P < 0.05). A menton deviation of 3° can induce abnormally increased visual attention to the lower face in both orthognathic patients and persons without facial deformities. With increased menton deviation, this trend will be more obvious, and the visual attention to the eyes and nose will also be affected, especially for persons without facial deformities, attention to the eyes will be significantly reduced.

Association of the three-dimensional skeletal variables with self-recognition of facial asymmetry in skeletal Class III patients.

To investigate the association between three-dimensional (3D) skeletal variables and self-recognition of facial asymmetry in skeletal Class III patients. Questionnaires and cone beam computed tomography of 74 patients (42 men and 32 women; mean age: 22.8 ± 4.5 years) with skeletal Class III and facial asymmetry were collected retrospectively. Patients were classified into three groups: group Sy (recognition of symmetry), group NS (not sure), and group Asy (recognition of asymmetry), according to their responses to the questionnaires. To assess 3D anatomic differences in the maxillomandibular region, six 3D hard tissue variables: maxillary height, ramal length, frontal ramal inclination (FRI), lateral ramal inclination (LRI), mandibular body length (Mn BL), and mandibular body height (Mn BH) were compared among the three self-recognition groups. Six 3D hard tissue variables and Menton deviation were reduced into three factors and their association with the self-recognition of facial asymmetry was investigated. Maxillary height, FRI, LRI, Mn BH, and Menton deviation demonstrated significant differences among the three self-recognition groups. The reduced factors, which consisted of transverse and vertical parameters, and vertical parameter of the mandibular corpus, demonstrated significant differences among the three self-recognition groups. The difference in Mn BH influenced the self-recognition of facial asymmetry. Both the transverse and vertical parameter of the skeleton were determinant in self-recognition of facial asymmetry. Identification of the skeletal difference in the lateral view involving LRI and Mn BH should be included for assessment of facial asymmetry.

A preliminary study of buccal and lingual alveolar bone thickness of posterior teeth in patients with skeletal Class III malocclusion and mandibular asymmetry

The purposes of this retrospective study were to investigate the buccal and lingual alveolar bone thickness values of the posterior teeth in patients with asymmetrical skeletal Class III malocclusion and compare them with patients with symmetrical skeletal Class III and Class I malocclusion. Seventy-eight cone-beam computed tomography scans were classified into 3 groups according to the sagittal pattern and menton deviation: asymmetrical Class III (n= 26), symmetrical Class III (n= 26), and symmetrical Class I (n= 26). The buccal and lingual alveolar bone thickness of the first molar and premolars in the maxilla and mandible were measured at 3, 6, and 8 mm apical to the cementoenamel junction and the apical and middle levels of the root. Measurements were compared among the 3 groups. In the asymmetrical Class III group, the buccal alveolar bone along the distobuccal root of the maxillary first molar on the deviated side was thinner by 1.07 to 1.10 mm than that in the symmetrical Class I group at 6-mm, 8-mm, and middle-level planes (P<0.001, P<0.01, and P<0.001). The buccal alveolar bone thickness along the distal and mesial roots of the mandibular first molar on the deviated side was thinner by 1.28 to 1.85 mm, and by 0.72 to 1.21 mm, respectively (P <0.001 and P <0.01), than that in the symmetrical Class I group at 6-mm, 8-mm, apical and middle-level planes. In this preliminary study, patients with skeletal Class III malocclusion showed thinner buccal and lingual alveolar bone in the posterior teeth than subjects with Class I malocclusion. Particular attention should be paid to buccal alveolar bone thickness along the distobuccal root of the maxillary and distal root of the mandibular first molar to prevent periodontal complications in decompensation. Future studies should involve larger sample sizes, more repeatable and comprehensive measuring and statistical methods.

Facial visual attention to menton deviation: An objective evaluation by laypeople

PurposeThis study aimed to quantitatively evaluate whether the severity of menton deviation (MD) influenced facial perceptions of laypeople. We also aimed to determine the effectiveness of surgery in normalizing the distribution of the facial visual attention of laypeople. MethodsThe scanning paths of 177 laypeople were recorded using an eye tracking device while observing images of individuals without MD and pre- and post-treatment subjects with different degrees of MD. The fixation durations on the areas of interest (AOIs) in each group were compared and analysed. ResultsWhen observing the images of non-MD subjects, the eyes were the focus of the most significant fixation (higher than the fixations on the nose and lower face). When the MD increased to 3°, attention on the lower face increased (p = 0.001) with decreased attention to the eyes (p = 0.0126). At an MD of 9°, attention to the lower face sharply increased, even more so than that to the eyes, with decreased attention to the nose (p = 0.0104). Compared with the findings for the post-treatment images, the laypeople who observed the pretreatment images focused longer on the lower face and less on the eyes and nose (p = 0.001, p = 0.0322 and p = 0.0023, respectively). The distribution of the fixation duration when observing the post-treatment images was similar to that when observing the images of the non-MD subjects. ConclusionsLaypeople can perceive an MD of 3°, which causes changes in the distribution of visual attention, with attention focusing on the MD. When the deviation reaches 9°, it is very noticeable. Surgery can normalize the distribution of the facial visual attention of laypeople, as shown by the responses to the post-treatment images.

Correlation between the position of the glenoid fossa and condylar translational movement in skeletal Class III mandibular asymmetry patients.

SummaryObjectivesUnderstanding the mechanism of mandibular asymmetry (MA) is important to provide suggestions for occlusal treatment and to know the developmental process of masticatory dysfunction. To investigate the morphological and functional effects on MA, we evaluated the three-dimensional position of the glenoid fossa and its relationship to asymmetrical condylar translational movement.MethodsIn this retrospective study, 50 subjects who previously underwent computed tomography for surgical purposes were divided into MA and control groups according to a menton deviation of at least 4 mm from the mid-sagittal plane. The glenoid fossae positions were evaluated using a three-dimensional analysis program. Condylar translational movements were recorded and measured by computerized axiography on protrusion. Side-to-side asymmetry was measured for each parameter. Asymmetry index value was calculated to assess the correlation between glenoid fossa position and condylar movement. Wilcoxon’s signed-ranked test, Mann–Whitney U-test, and Spearman’s rank correlation were used for the statistical analysis.ResultsIn the MA group, glenoid fossa position on the shifted side was significantly inferior and posterior as compared to that on the non-shifted side and of the control group. Condylar path length and sagittal condylar inclination were significantly greater on the shifted side versus non-shifted side, while no significant difference was found in transverse condylar inclination. The asymmetry index of the anterior–posterior glenoid fossa position was significantly correlated with that of condylar path length and bilateral transverse condylar inclination. In the control group, there were no significant correlations among the morphological and functional parameters.LimitationsThis study did not consider muscle activity and disc position, which may affect condylar movement.ConclusionsFunctional asymmetry of condylar translational movements is closely related to asymmetry of glenoid fossa position in MA patients.

Mandibular Stability After Sagittal Split Ramus Osteotomy With Hybrid Technique in Asymmetric Patients.

The hybrid technique after bilateral sagittal split ramus osteotomy is an internal fixation method using monocortical mini-plates and additional bicortical positional screws. In this study, we analyzed the postoperative stability of 23 patients with mandibular asymmetry who underwent bilateral sagittal split ramus osteotomy and hybrid fixation with or without LeFort I osteotomy. Anatomical landmarks of the deviated and non-deviated sides of the jaw were established to measure the angle and distance to the reference plane in three-dimensional cone beam computed tomography images. We analyzed the positional changes and correlations of the reference points at preoperative (T1), postoperative 2 weeks (T2), and postoperative 1 year (T3). There were significant differences in preoperative position of the upper and lower molar cervix alveolar crest to the reference plane (U6-X and L6-X) and the condylion angles between deviated and non-deviated sides. Postoperatively (T2-T3), each reference point had no statistically significant positional change. Pearson correlation coefficient between the amount of menton deviation (ME-X at T1) and positional change of menton after surgery (T2-T3) was 0.30, and P value was 0.168. The hybrid fixation technique is an effective fixation method for achieving postoperative stability for mandibular asymmetry.

Type of mandibular asymmetry affects changes and outcomes of bimaxillary surgery for class III asymmetry.

Various methods have been used to classify class III asymmetry. There is little information on the use of an asymmetry index to examine soft tissue changes and outcomes for patients with class III asymmetry. This study aimed to (1) evaluate soft tissue changes and outcomes for three types of mandibular asymmetry and (2) determine if measures are associated with type of asymmetry. Adults who consecutively underwent bimaxillary surgery using surgery-first approach for correction of class III asymmetry were divided into three groups based on type of mandibular asymmetry. This previously reported classification system is simple and mutually independent, categorizing mandibular asymmetry according to the amount and direction of ramus asymmetry relative to menton deviation: patients with a larger transverse ramus distance on the menton deviation side were divided into group 1 and group 2; group 1 (n = 45) exhibited a menton deviation larger than ramus discrepancy; group 2 (n = 11) exhibited a menton deviation less than ramus discrepancy; group 3 (n = 22) had larger transverse ramus distance contralateral to the side of the menton deviation. Soft tissue facial asymmetry indices, calculated from cone beam computed tomography images, assessed midline and contour asymmetry presurgery, changes postsurgery, and outcomes. Compared with groups 1 and 2, the presurgery index for contour and midline asymmetry was smallest for group 3. All the three groups had significant improvement in midline asymmetry postsurgery, and outcome measures were good; there were no differences between groups. However, contour asymmetry only improved significantly for groups 1 and 2. The outcome for contour asymmetry was fair for groups 1 and 3 and poor for group 2. Bimaxillary surgery significantly improved facial midline asymmetry. The type of mandibular asymmetry was associated with postsurgical changes and outcomes for contour asymmetry. Understanding the types of mandibular asymmetry could help clinicians to develop treatment plans and predict treatment changes and outcomes.

Does maxillary yaw exist in patients with skeletal Class III facial asymmetry?

This study aimed to evaluate maxillary skeletal and dental yaw in patients with skeletal Class III facial asymmetry and investigate its correlation with menton deviation. Initial cone-beam computed tomography data from 60 patients with skeletal Class III malocclusion were used. There were 30 patients in both the symmetrical group (menton deviation<2mm) and the asymmetrical group (menton deviation>4mm). After reconstruction of 3-dimensional (3D) cone-beam computed tomography data, maxillary yaw and 3D positions of skeletal and dental landmarks were measured and compared between the groups. After that, correlations between menton deviation and the other variables were assessed. No significant difference was noted in maxillary skeletal and dental yaw between the 2 groups. In the assessment of 3D positions, translation of the maxillary bone and maxillary dentition toward the menton deviation was observed (P<0.01). Maxillary skeletal and dental yaw was not significantly correlated with menton deviation in the asymmetrical group. Maxillary skeletal and dental yaw was not evident in either group. Therefore, when planning maxillary surgery for patients with skeletal Class III facial asymmetry malocclusion, it may be appropriate to shift the focus of decompensation from maxillary yaw to maxillary translation.

The effect of TMJ disk repositioning by suturing through open incision on adolescent mandibular asymmetry with and without a functional orthodontic appliance

The objective of this study was to evaluate the effect of combined temporomandibular joint (TMJ) disk repositioning by suturing through open incision and orthodontic functional appliance (OFA) treatment for adolescents with mandibular asymmetry. Adolescent patients (12-20 years old) with mandibular asymmetry combined with unilateral TMJ disk displacement without reduction were treated with disk repositioning by suturing through open incision with and without postoperative OFA. Magnetic resonance imaging and posteroanterior cephalometric radiographs (PA) were used to measure and compare the changes in condylar height, joint space, and menton deviation pre- and postoperatively. Twenty-six patients were included in the study. Joint space was significantly increased postoperatively and new bone mostly formed at the superior or posterior superior part of the condyle after 6 to 18 months in all surgically treated joints. Fourteen patients with OFA had a significant increase in condylar height and menton deviation compared to 12 patients without OFA (2.29 ± 0.91 mm vs 1.22 ± 0.69 mm, P=.003; 4.56 ± 1.48 mm vs 2.01 ± 0.74 mm, P=.000). Combined treatment with TMJ disk repositioning by suturing through open incision and OFA can promote condylar growth and correct mandibular deviation in adolescent patients. Postoperative OFA can maintain the increased joint space created by disk repositioning and promote new bone formation at the superior and posterior parts of the condyle.

Comprehensive 3D analysis of condylar morphology in adults with different skeletal patterns \u2013 a cross-sectional study

BackgroundThe correlation between individuals’ condylar morphology and their skeletal pattern is of great interest for treatment strategies ranging from orthodontic orthopaedics to orthognathic surgery. The objective of the present study was to investigate this relationship three-dimensionally.MethodsA total of 111 adult patients (mean age = 27.0 ± 10.2 years) who underwent head computed tomography or cone beam computed tomography scans were included. Based on these data, 3D models of the skull and the condyles were calculated. The craniofacial skeleton was evaluated (1) transversally regarding skeletal symmetry (menton deviation), (2) sagittally regarding skeletal classes (Wits appraisal) and vertically regarding the inclination of the jaws (maxillomandibular plane angle). The condylar morphology was assessed (a) linearly by the condylar width, height and depth; (b) angularly by the antero-posterior and medio-lateral condylar inclination; and (c) volumetrically by the ratio of the condylar volume/mandibular volume (C/Mand).Results(1) Transversal: Asymmetric patients showed significantly higher discrepancies in the volumetric ratio C/Mand on the deviation and non-deviation side compared to symmetric patients. (2) Sagittal: Class III subjects demonstrated longer, more voluminous condyles with higher antero-posterior and medio-lateral inclination angles compared to Class II participants. (3) Vertical: Hyperdivergent subjects had smaller condyles with higher antero-posterior inclination angles than those of hypodivergent subjects. No interactions of skeletal class and vertical relationships regarding condylar morphology were observed.ConclusionsThis study demonstrates a clear correlation between pronounced skeletal patterns and condylar morphology in an adult population. The description of radiographic condyle characteristics in relation to the craniofacial morphology improves orthodontic treatment planning and could be helpful in the diagnosis of temporomandibular joint pathologies.

Relationship between menton deviation and temporomandibular disc displacement in adult patients

ABSTRACT Purpose: This study investigated the relationships among characteristics of maxillomandibular asymmetry in patients with menton deviation and temporomandibular joint (TMJ) disc conditions, including normal disc position (NDP), anterior disc displacement with reduction (ADDwR), rotational disc displacement with reduction (RDDwR), and anterior and/or rotational disc displacement without reduction (DDwoR). Materials and methods: Eighty-six patients with menton deviation (62 female patients and 24 male patients) were included. The TMJ magnetic resonance images were categorized into four groups: bilateral-NDP (n = 15), ADDwR (n = 13), RDDwR (n = 19) and DDwoR (n = 39). The characteristics of menton deviation and maxillomandibular asymmetry were determined using posteroanterior and lateral cephalograms. Differences in cephalometric variables among the groups were statistically analysed. Results: Patients with menton deviation under Skeletal Class I, and Skeletal Class II relationship showed a higher rate of DDwoR on lateral cephalograms. Significant differences were detected among groups on posteroanterior cephalograms with respect to the cant of the frontal mandibular plane and menton deviation. These two variables were significantly greater in the DDwoR group than in the bilateral-NDP group. Conclusion: The anteroposterior jaw relatioship and mandibular deviation may be associated with the severity of TMJ disc displacement.