Clinical and radiographic features of temporomandibular joint in patients with facial asymmetry

PURPOSE

The purpose of this study was to investigate characteristics of mandibular head morphology and temporomandibular joint (TMJ) disorders (TMDs) on the deviation side (DS) and non-deviation side (NDS) in patients with facial asymmetry (FA).

METHODS

Thirty patients diagnosed with FA were enrolled. Preoperative and postoperative joint sound and pain were evaluated in terms of clinical symptoms, and pre- and postoperative mandibular head morphology factors shown by computed tomography. In addition, magnetic resonance imaging findings were used to evaluate preoperative joint disc position and joint effusion (JE).

RESULTS

The patients included 12 (40.0%) males and 18 (60.0%) females, with a mean age of 25.8 years. There were no significant differences regarding clinical symptoms between patients affected on the DS and those on the NDS. Preoperatively, the DS group showed a total of 4 joints (13.3%) with mandibular condyle head deformity, while postoperatively those patients had 13 (43.3%) and the NDS group 2 (6.7%), indicating a significant difference for condyle head deformity between patients affected on DS and NDS before and after surgery. The score for JE was 1.1 ± 1.0 in the DS group and 0.6 ± 0.8 in the NDS group, a significant difference (P < 0.05).

CONCLUSION

As compared to the NDS, the DS in the present class III patients with FA showed a greater number of TMDs, such as condyle head deformity, disc displacement, and JE. It's important for surgeons and orthodontists to be aware of the possibility of TMDs on the DS in class III patients with FA when performing orthognathic surgery.

Changes in Facial Soft Tissue Asymmetry in Class II Patients One Year After Orthognathic Surgery

Objectives: The objective of this study was to examine changes in facial soft tissue asymmetry over time in patients after Class II orthognathic surgery using three-dimensional (3D) stereophotogrammetry. Methods: The study consists of 54 patients with a skeletal Class II malocclusion (32 female, 22 male; mean age, 33.2 years). Three-dimensional photographic data were collected using the 3dMD Trio stereophotogrammetry system. The evaluation of 21 anthropometric landmark positions was conducted before surgery (T0), 6 months (T1), and 12 months (T2) after surgery. Facial asymmetry was classified as mild (0-2 mm), moderate (3-5 mm), or severe (>5 mm). Results: There was a small difference in the mean distance when analyzing the asymmetry of the whole face. The 3D measurements showed statistically significant differences (p < 0.05) between T0 versus T1 and T2 time-point values. Prior to surgery, males exhibited a higher degree of soft tissue asymmetry compared to females. The chin volume asymmetry score was higher in the females of the cohort and patients undergoing bimaxillary surgery (median 1.11) than in the males of the cohort and patients undergoing single-jaw surgery (median 1.08); however, these differences were not statistically different. Conclusions: The findings indicate that soft tissue asymmetry may become altered within a 6-month period following surgery.

Associations of Digital Measurements: Analysis of Orthopantomography Versus Lateral Cephalograms for Evaluation of Facial Asymmetry

Background/Objectives: This study aimed to compare the associations of digital measurements obtained from orthopantomographies (OPGs) or panoramic radiographs and lateral cephalograms in evaluating facial asymmetry in patients with different skeletal classes. The sample consisted of 128 Romanian patients (67 females, 61 males) who sought orthodontic treatment. These measurements are an essential diagnostic tool for evaluating facial asymmetry in order to treat them. Methods: Lateral cephalograms and OPGs were obtained for each patient, and digital tracing was performed using the WebCeph program. Angular measurements (ANB, FMA, gonial angles) and linear measurements (ramus height, mandibular body length) were assessed on both imaging modalities. Results: Strong positive correlations were found between the gonial angle and ramus height measurements obtained from lateral cephalograms and OPGs (rs range: 0.800-0.946; p < 0.001). However, the mandibular body length showed weaker correlations between the two methods. Significant sex differences were observed, with males exhibiting larger craniofacial measurements compared to females (p < 0.05). The study population was quite young, as seen by the cohort's median age of 21 years and interquartile range (IQR) of 16 to 29 years. Lateral Ceph: the FMA angle median value of 22° (IQR: 17-25), gonial angle median of 121° (IQR: 116-127), mandibular ramus height median value of 44 mm (IQR: 41-48 mm), and mandibular body length median value of 70 mm (IQR of 65 to 76 mm). OPG: gonial angles on the right and left sides yield medians of 121° (IQR: 116-127) and 122° (IQR: 117-127); the mandibular ramus height on the right and left sides shows medians of 44.0 mm (IQR: 40.0-47.0 mm) and 43 mm (IQR: 40-48 mm); and the mandibular body on the right side presents a median of 71 mm (IQR: 67-76 mm) and the left side has a median of 71 mm (IQR: 67-75 mm). Conclusions: The findings suggest that OPGs can be reliably used to measure the gonial angle and ramus height, providing results comparable to lateral cephalograms. However, caution should be exercised when predicting horizontal measurements from OPGs. The standardization of the OPG recording process and further research with larger sample sizes are required to establish standard panoramic norms for OPG parameters in the assessment of facial asymmetry.

Comparison of the asymmetry index determined on digital panoramic radiographic images and on posteroanterior cephalometric images: a retrospective cross-sectional study

OBJECTIVE

The purpose of this study was to compare the asymmetry index determined on digital panoramic radiographic (PR) images and posteroanterior cephalometric (PACR) images.

METHODS

This study included 100 patients whose PR and PACR images were registered in a database. Condylar height, ramus height, and condylar height plus ramus height measurements were measured bilaterally. Condylar asymmetry, ramus asymmetry, and total asymmetry were evaluated.

RESULTS

There was a statistically significant difference between the right and left side for all measurements when evaluated on the PR and also on the PACR images (p < 0.01). When calculating the asymmetry index, the resulting condylar asymmetry and ramus asymmetry values did not show significant differences between PR and PACR images. On the other hand, only the presence of total asymmetry showed a statistically significant difference between techniques (p = 0.013).

CONCLUSION

Asymmetry indices can be reliably obtained from both PR and PACR images.

3D Facial Analysis in Class II Subdivision Malocclusion

Background:

Class II subdivision is an asymmetric condition presenting a Class I dental occlusion on one side and a Class II on the contralateral one. It presents a midline deviation that may be caused by a monolateral distalization of the mandible (type 1) or a mesialization of one side of the maxilla (type 2). The evaluation of asymmetry based on 2D radiographic records has been demonstrated to be less accurate than the one made using 3D radiographs.

Objective:

The aim of this work is to evaluate the facial asymmetry in a group of patients with Class II subdivision, compared to patients in Class I without evident asymmetry, by using 3D photographs of the face.

Methods:

32 young adults with Class II subdivision were compared to a group of 32 subjects with bilateral Class I molar relationship. 3D photograph of their face was acquired using a stereophotogrammetric camera (3dMDtrio System-3dMD Atlanta, GA, USA). 3D photographs were imported into the Geomagic Software to create mirror 3D photography. Independent T-tests were made to compare facial asymmetries measured on Class II subdivision group with the Class I group.

Results:

The results show that there is a statistically significant difference in landmarks location between the control group and the experimental group regarding the values measured at the level of the lips and the perioral area. The asymmetry was more marked in patients with mandibular midline deviation. This is in line with previous observations with radiographic investigations.

Conclusion:

For a correct assessment of the asymmetry, a study of 3D photographs cannot replace an evaluation by cone beam, but it can be an important aid to estimate possible asymmetries in the perioral area and in the lip area.

A 3D mirroring and colormap asymmetry study of Class II subdivision patients

INTRODUCTION

Patients with Class II subdivision malocclusion present skeletal and dental asymmetries. The purpose of this study is to assess those asymmetries by 3D mirroring and colormap quantification.

METHODS

This study analyzed 50 initial CBCTs divided into two groups: Class I (control group) and Class II subdivision (study group) malocclusion patients. CBCTs were oriented and full skull was segmented generating a 3D model. The right side of the 3D models was mirrored, using a midsagittal plane as reference, resulting in a perfectly symmetric skull based on two right sides. Original and mirrored models were superimposed on the unchanged right half, and differences were quantified using a colormap. Eight regions of interest were assessed: gonion, mandibular front, maxillary front, zygomatic process, maxillary and mandibular canine and molar areas.

RESULTS

Statistically significant differences using the Mann-Whitney test were found in six of the eight evaluated areas when comparing the control to the study group. The maxillary skeletal areas did not show any difference between the groups.

CONCLUSIONS

Patients with Class II subdivision malocclusion show true skeletal and dental asymmetries when comparing right and left sides. The maxilla showed no significant skeletal asymmetry, but the maxillary teeth were positioned more mesially on the Class II side. The maxillary canine on the Class II side was also more bucally positioned. The mandible showed significant asymmetries with both skeletal and dental areas in the Class II side more distally and bucally positioned.

Class II subdivision: Cone beam computed tomography- CBCT Analysis

Background

To estimate whether there is skeletal and/or dental asymmetry in class II subdivision patients, between the Class II side and the Class I side using of cone beam computed tomography (CBCT).

Material and Methods

A sample of 30 patients, from a private clinic, retrospectively selected; with a class II subdivision diagnosis requiring treatment, who underwent wide-field CBCT that met the inclusion criteria. The data was processed with Dolphin 3D version 11.95 Premium software. The craniometric points, as well as the spatial orientation scheme of the three-dimensional model were proposed by Craig Minich, et al. (1).

Results

The Class II subdivision side and the Class I side of each patient were compared through intramaxillary, intramandibular, and intermaxillary measurements, evaluating each one in three dimensions (sagittal, frontal, and axial). Also, the measurements made from the three-dimensional volume, were contrasted with those generated in the biplane views. The level of significance used was 0.05. Statistical analysis was performed using the R program (R Development Core Team), version 3.4.4. The intraoperative variability was previously verified using the Dahlberg formula. This error is 0.35 -1.10, so the spatial orientation and placement of craniometric points are repeatable and reliable.

Conclusions

Statistically significant differences have been found with respect to skeletal values and dentoalveolar position. Regarding the skeletal findings, the class II subdivision side is narrower and there is a shortening of the condylar branch. In the dentoalveolar position on this side, the upper molar and canine are in an advanced position, the lower molar is posterior and lower than the contralateral and the lower canine is in a delayed position. Furthermore, measurements made from a two-dimensional image cannot be extrapolated with those made directly from a three-dimensional volume. The problem is generated by a deviation in dental position as well as an underlying asymmetry.

Key words:Class II subdivision, cone beam computed tomography, skeletal asymmetry, dentoalveolar position.

Analysis of hard tissue facial symmetry after unilateral mandibular reconstruction

Background

This study aimed to determine how successful reconstruction of the mandible can recover the symmetry.

Materials and methods

All patients who underwent surgical treatment for unilateral mandibular reconstruction in 4 years were retrospectively examined. Bilateral differences of gonion (GO) positions were measured in 3 dimensions based on immediate postoperative computed tomography. The data collected was analyzed in 3 ways: First, the comparison of bilateral differences of GO in 3 dimensions. Second, the mean Asymmetry Index in control subjects was used to divide all cases into three groups: “Symmetry,” “Asymmetry,” and “Marked asymmetry.” Third, “maximum normal asymmetry” was calculated, and all cases were categorized as below and above maximum normal asymmetry. The difference between two gonial angles was used to determine the amount of asymmetry.

Results

Forty-seven patients and 47 normal adults were enrolled. The mean bilateral GO difference in the control group was higher than in the study group patients, but it was not statistically significant. The mean Asymmetry Index for the control group was not also significantly higher than the study cases. The study group was “Symmetric” in 78.7% of the cases whereas the control group in 91.4%, 19.1% of the study group and 8.5% of controls were “Asymmetric,” and 2.1% of study cases and 0% of controls were “Markedly Asymmetric.” Maximum normal asymmetry was 82.9% in the study group and 97.8% in the control group. The mean differences between the right and left gonial angles were higher in the study group, but it was not significant (P = 0.1).

Conclusions

Our study’s results showed that bilateral symmetry in mandibular reconstruction patients was satisfactory and similar to the normal individuals.

Digital Radiographic Study of Gonial angle in Forensic Odontology in a Tertiary Care Centre: A Descriptive Cross-sectional Study

Introduction:

Gonial angle measurements serve as an important parameter of the craniofacial complex and are usually studied on lateral cephalograms, but recently panoramic radiographs have also been used. The aim of this study is to measure the gonial angle using orthopantomogram and lateral cephalogram based on age, gender, ethnicity, and skeletal malocclusion in a tertiary care hospital.

Methods:

This is a descriptive cross-sectional study comprising 350 selected radiographs of apparently healthy individuals collected for a period of one year, from the Department of Oral Radiology of a tertiary care centre of Nepal. Gonial angle measurements were recorded from digital panoramic radiograph (both right and left side) and lateral cephalogram. Data was collected in terms of age, gender, ethnicity, and skeletal malocclusion and then statistically analysed using the Statistical Package for the Social Sciences version 20.

Results:

The mean gonial angle for panoramic right, left and lateral cephalogram was 122.490±7.570, 123.620±7.060, and 124.150±6.910, respectively. There was a decrease in the mean values of the gonial angle observed as age advances seen in all the radiographs. The gonial angle measured in Class III malocclusion was higher in all the radiographs, followed by Class II and Class I. Gonial angles obtained in females were higher than the males in all the radiographs. Finally, the Aryan population showed a higher gonial angle compared to the Mongolian population in all the radiographs.

Conclusions:

Panoramic radiograph (left side), could be considered as a reliable tool to measure the gonial angle.

Asymmetric dental arch treatment with Forsus fatigue appliances: Long-term results

OBJECTIVES

To investigate the treatment efficacy and follow-up stability of the asymmetric Forsus appliance by evaluating longitudinal changes in dental arch asymmetry on digital dental models from 21 patients.

MATERIALS AND METHODS

Maxillary and mandibular reference lines were used for measurements of intra-arch asymmetry at pretreatment (T1), posttreatment (T2), and 4.2 years after treatment (T3). Maxillary and mandibular measurements were performed relative to the dental midline and anterior reference line on digital dental models. To determine the amount of asymmetry between the Class I and Class II sides of a given arch, all maxillary and mandibular parameters were measured on each side of the model separately. Repeated-measures analysis of variance/paired sample t-tests were performed to evaluate dental arch asymmetries at the P < .05 level.

RESULTS

The alveolar transverse dimensions of the posterior segment of both arches were increased during treatment (P < .05) and remained stable during the retention period. Class II subdivision malocclusion was caused by distal positioning of the mandibular canine, premolars, and first molar on the Class II side (P < .05). Asymmetry was resolved by treatment with asymmetric Forsus appliances. The resolved asymmetry remained stable over the long term. There were no significant differences between T2 and T3 (P > .05).

CONCLUSIONS

The asymmetric Forsus appliance can be used to treat dental arch asymmetry in patients with Class II subdivision malocclusions.

Environmental temperature and air humidity and prevalence of maxillary sinus retention cysts: possible relationships (preliminary study)

OBJECTIVES

The aims of this study were to determine the prevalence of maxillary sinus retention cysts (MSRCs) and to evaluate the effects of mean temperature and mean air humidity on the prevalence of MSRCs in two cities in Turkey.

METHODS

This retrospective study was conducted in Antalya and Erzurum, two cities with different air humidities and temperatures in Turkey. Panoramic images of patients who visited the Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Akdeniz University and Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Ataturk University for diagnostic purposes were evaluated. A total of 4800 panoramic images were included in the study. The mean age of the patients was 27.03 ± 6.48 years. The prevalence of MSRCs was analyzed according to sex, mean temperature, and mean air humidity. Values of p < 0.05 were considered statistically significant.

RESULTS

Among the 4800 panoramic images evaluated, 228 indicated the presence of MSRCs. MSRCs were found significantly more frequently in males than in females. The prevalence was 3% in Antalya and 6.5% in Erzurum, with a total prevalence of 4.8%. While there was a significant correlation between the total amount of cysts and monthly mean air humidity in Erzurum, the correlation effect size was very low.

CONCLUSIONS

The total prevalence of MSRCs was 4.8%. There were no correlations between the frequency of MSRCs and the mean air humidity or mean temperature.

Linear and Volumetric Mandibular Asymmetries in Adult Patients With Different Skeletal Classes and Vertical Patterns: A Cone-Beam Computed Tomography Study

This study aimed to quantify the height of the mandibular condyle and ramus, condylar volume, and the asymmetry index in adult patients of different sex, skeletal class and vertical pattern using Cone-Beam Computed Tomography (CBCT), and to determine whether there were differences between these groups. The study used CBCT scans of 159 patients with a mean age of 32.32 ± 8.31 years. InVivoDental® software was used to perform both linear (condylar, ramal, and total height) and condylar volume measurements. Linear and volumetric asymmetries were calculated. There were not significant differences between right and left sides. The mean value obtained for condyle height was 7.27 mm, ramus height 42.3 mm, total height 49.6 mm and condyle volume 1907.1 mm3, with significant differences between men and women. Significantly higher values were found for condylar volume in hypodivergent patterns (p = 0.001) and for the asymmetry index of the condylar volume in Class II patients (p < 0.05). The prevalence of relevant asymmetry was high for condyle height and volume (73.1% y 75.6% respectively). Higher height and volume values were found among men, Class III, and hypodivergent patients. Linear and volumetric asymmetries were more prevalent among men, Class III and hyperdivergent patterns.

[Mandibular asymmetry: determination of a reliable skin measurement technique]

INTRODUCTION

Clinical measurements in the frontal view underevaluate chin deviation in mandibular asymmetry. The aim of this descriptive study is to search for a reliable method of measuring deviant chins using a facial X-ray as reference.

MATERIAL AND METHOD

Seventy patients with mandibular asymmetry who had consulted a maxillofacial surgeon were systematically included. Age, sex, cephalometric characteristics, reasons for patient consultation and type of surgery were collected. Two cephalometric methods were tested with respect to the medial sagittal plane (PSM) to compare the assessment of mandibular asymmetry on soft tissue and by cephalometry.

RESULTS

On average, the patients selected were young (26 years +/- 9), women (75% of cases), presented open bite (average FMA: 28° +/- 8°), a skeletal class III tendency, a left-side shift of the chin (63% of cases). They consulted for both aesthetic and functional reasons (51% of cases) and required bimaxillary surgery (66% of cases). Comparison between the photographic angle (formed by the PSM and the line passing through the nasion and reaching the chin point) and the radiographic angle (formed by the PSM and the line passing through the Crista Galli process and the bony chin point angle) showed no significant difference (p = 0.937) and is thus reliable.

Reliability and validity of mandibular posterior vertical asymmetry index in panoramic radiography compared with cone-beam computed tomography

INTRODUCTION

The purposes of this study were to compare the asymmetry index using panoramic radiography and cone-beam computed tomography for detecting mandibular posterior asymmetry and to evaluate the diagnostic value of the asymmetry index on panoramic radiography.

METHODS

A total of 43 patients were included in this study. Ten mandibular posterior distances were measured using panoramic radiography and cone-beam computed tomography, and 10 asymmetry index values were calculated. The reliability of each asymmetry index was assessed. For evaluating validity of each asymmetry index using panoramic radiography, the paired t test and the Bland-Altman analysis were used. The accuracy of the asymmetry index and the area under the curve of receiver operator characteristic were calculated.

RESULTS

The asymmetry index of total ramal height showed good reliability (ICC, >0.888). In condylar height 1, specificity and negative predictive value were low (0.08 and 0.17, respectively), 95% limits of agreement were ±17.9%, and area under the curve was 0.484. In total, ramal height accuracy was 0.86, and areas under the curve were 0.926 to 0.957.

CONCLUSIONS

For detecting asymmetry of the condyle region, the asymmetry index using panoramic radiography had little diagnostic value, and we recommend using cone-beam computed tomography images. However, the asymmetry index for total ramal height showed good reliability and relatively higher validity, and its diagnostic value was excellent.

Cone Beam Computed Tomographic Evaluation of Mandibular Asymmetry in Patients with Cleft Lip and Palate

Objective:

The purpose of the present study was to compare mandibular vertical asymmetry in patients with unilateral and bilateral cleft lip and palate and subjects with normal occlusion.

Materials and Methods:

Cone beam computed tomography scans of three groups consisting of 20 patients with unilateral cleft lip and palate, 20 patients affected by bilateral cleft lip and palate, and a control group of 20 subjects with normal occlusion were analyzed for this study. Condylar, ramal, and condylar plus ramal asymmetry indices were measured for all subjects using the method of Habets et al. Kruskal-Wallis and Mann-Whitney tests were used to determine any significant differences between the groups for all indices at the 95% level of confidence.

Results:

There were no significant differences regarding sex for all mandibular asymmetry indices in all three groups. All Asymmetry indices (condylar, ramal, and condylar plus ramal asymmetry) were significantly higher in the unilateral cleft group compared with the other two groups.

Conclusion:

Cone beam computed tomography images showed that patients with cleft lip and palate suffered from mandibular asymmetry. Subjects with unilateral cleft lip and palate had a more asymmetric mandible compared with the bilateral cleft lip and palate and control groups. Therefore, the mandible appears to be the leading factor in facial asymmetry in subjects with unilateral cleft lip and palate.

Comparison of Orthopantomogram and Lateral Cephalogram for Mandibular Measurements

Aim:

The aim of the present study is to clarify the possible application of orthopantomogram (OPG) for evaluating craniofacial specifications such as angular and linear measurements of the mandible by comparing with lateral cephalogram.

Materials and Methods:

OPG and lateral cephalogram were taken from 100 patients of age group 16–35 years from Chettinad Dental College and Research Institute. Linear measurements (body length and ramus height) and angular measurement (gonial angle) were assessed both in lateral cephalogram and OPG. Independent t-test was performed for comparison of OPG and lateral cephalogram using SPSS with a probability level of P < 0.05 considered to be statistically significant.

Results:

The results of the present study show that there is no statistically significant difference in ramus height and gonial angle when compared between OPG and lateral cephalogram while statistically significant difference exists for body length between OPG and lateral cephalogram.

Conclusion:

It may be concluded that panoramic radiography can be used to determine the gonial angle and ramus height as accurately as a lateral cephalogram. However, clinicians should be vigilant when predicting horizontal measurement from OPGs.

Facial asymmetry: a current review

The term "asymmetry" is used to make reference to dissimilarity between homologous elements, altering the balance between structures. Facial asymmetry is common in the overall population and is often presented subclinically. Nevertheless, on occasion, significant facial asymmetry results not only in functional, but also esthetic issues. Under these conditions, its etiology should be carefully investigated in order to achieve an adequate treatment plan. Facial asymmetry assessment comprises patient's first interview, extra- as well as intraoral clinical examination, and supplementary imaging examination. Subsequent asymmetry treatment depends on patient's age, the etiology of the condition and on the degree of disharmony, and might include from asymmetrical orthodontic mechanics to orthognathic surgery. Thus, the present study aims at addressing important aspects to be considered by the orthodontist reaching an accurate diagnosis and treatment plan of facial asymmetry, in addition to reporting treatment of some patients carriers of such challenging disharmony.

Cone-beam computed tomographic evaluation of the temporomandibular joint and dental characteristics of patients with Class II subdivision malocclusion and asymmetry

OBJECTIVE

Treating Class II subdivision malocclusion with asymmetry has been a challenge for orthodontists because of the complicated characteristics of asymmetry. This study aimed to explore the characteristics of dental and skeletal asymmetry in Class II subdivision malocclusion, and to assess the relationship between the condyle-glenoid fossa and first molar.

METHODS

Cone-beam computed tomographic images of 32 patients with Class II subdivision malocclusion were three-dimensionally reconstructed using the Mimics software. Forty-five anatomic landmarks on the reconstructed structures were selected and 27 linear and angular measurements were performed. Paired-samples t-tests were used to compare the average differences between the Class I and Class II sides; Pearson correlation coefficient (r) was used for analyzing the linear association.

RESULTS

The faciolingual crown angulation of the mandibular first molar (p < 0.05), sagittal position of the maxillary and mandibular first molars (p < 0.01), condylar head height (p < 0.01), condylar process height (p < 0.05), and angle of the posterior wall of the articular tubercle and coronal position of the glenoid fossa (p < 0.01) were significantly different between the two sides. The morphology and position of the condyle-glenoid fossa significantly correlated with the three-dimensional changes in the first molar.

CONCLUSIONS

Asymmetry in the sagittal position of the maxillary and mandibular first molars between the two sides and significant lingual inclination of the mandibular first molar on the Class II side were the dental characteristics of Class II subdivision malocclusion. Condylar morphology and glenoid fossa position asymmetries were the major components of skeletal asymmetry and were well correlated with the three-dimensional position of the first molar.

Three-dimensional positional assessment of glenoid fossae and mandibular condyles in patients with Class II subdivision malocclusion

OBJECTIVES

To test the null hypotheses that the positions of the glenoid fossae and mandibular condyles are identical on the Class I and Class II sides of patients with Class II subdivision malocclusion.

MATERIALS AND METHODS

Retrospective three-dimensional (3D) assessments of the positions of the glenoid fossae and mandibular condyles were made in patients with Class II malocclusion. Relative to a fiducial reference at the anterior cranial base, distances from the glenoid fossae and condyles were calculated in pretreatment cone beam computed tomographic scans of 82 patients: 41 with Class II and 41 with Class II subdivision malocclusions. The 3D distances from glenoid fossae to sella turcica in the X (right-left), Y (anterior-posterior), Z (inferior-superior) projections were calculated.

RESULTS

Patients with Class II malocclusion displayed a symmetric position of the glenoid fossae and condyles with no statistically significant differences between sides (P > .05), whereas patients with Class II subdivision showed asymmetry in the distance between the glenoid fossae and anterior cranial base or sella turcica (P < .05), with distally and laterally positioned glenoid fossae on the Class II side. (P < .05). Male patients had greater distances between glenoid fossae and anterior cranial fossae (P < .05). The condylar position relative to the glenoid fossae did not differ between the two malocclusion groups nor between males and females (P > .05).

CONCLUSIONS

The null hypotheses were rejected. Patients with Class II subdivision malocclusion displayed asymmetrically positioned right- and left-side glenoid fossae, with a distally and laterally positioned Class II side, although the condyles were symmetrically positioned within the glenoid fossae.

Class II subdivision treatment with the Forsus Fatigue Resistant Device vs intermaxillary elastics

OBJECTIVE

To compare the effectiveness of comprehensive fixed appliance treatments implemented in combination with Forsus or intermaxillary elastics in Class II subdivision subjects.

MATERIALS AND METHODS

Twenty-eight Class II subdivision patients were allocated to two groups using matched randomization: Forsus group (mean age, 14.19 ± 1.02 years) and elastics group (mean age, 13.75 ± 1.16 years). Patients received fixed appliance therapy in combination with either Forsus or intermaxillary elastics. The study was conducted on lateral cephalograms and digital models acquired before orthodontic treatment and 10-12 weeks after the fixed appliances were removed.

RESULTS

The treatment phase comprising the use of Forsus (4.53 ± 0.91 months) was significantly shorter compared with elastics application (6.85 ± 1.08 months). This was also true for comparing duration of overall comprehensive treatment in both groups. Extrusion and palatal tipping of maxillary incisors and clockwise rotation of the occlusal plane were greater in the elastics group (P < .05). The mandibular incisors were proclined in both groups (P < .001), but no significant difference was observed between groups (P > .05). The mandibular incisors showed intrusion in the Forsus group and extrusion in the elastics group; the difference between groups was significant (P < .05). Overbite was decreased in both groups (P < .001) in similar amounts. Improvement in overjet, mandibular midline deviation, and correction of molar relationship on the Class II side were greater in the Forsus group (P < .05).

CONCLUSION

Forsus is more effective for correcting Class II subdivision malocclusion in a shorter treatment period with minimal patient compliance required.

3D Mandibular Superimposition: Comparison of Regions of Reference for Voxel-Based Registration

Introduction

The aim was to evaluate three regions of reference (Björk, Modified Björk and mandibular Body) for mandibular registration testing them in a patients’ CBCT sample.

Methods

Mandibular 3D volumetric label maps were built from CBCTs taken before (T1) and after treatment (T2) in a sample of 16 growing subjects and labeled with eight landmarks. Registrations of T1 and T2 images relative to the different regions of reference were performed, and 3D surface models were generated. Seven mandibular dimensions were measured separately for each time-point (T1 and T2) in relation to a stable reference structure (lingual cortical of symphysis), and the T2-T1 differences were calculated. These differences were compared to differences measured between the superimposed T2 (generated from different regions of reference: Björk, Modified Björk and Mandibular Body) over T1 surface models. ICC and the Bland-Altman method tested the agreement of the changes obtained by nonsuperimposition measurements from the patients’ sample, and changes between the overlapped surfaces after registration using the different regions of reference.

Results

The Björk region of reference (or mask) did work properly only in 2 of 16 patients. Evaluating the two other masks (Modified Björk and Mandibular body) on patients’ scans registration, the concordance and agreement of the changes obtained from superimpositions (registered T2 over T1) compared to results obtained from non superimposed T1 and T2 separately, indicated that Mandibular Body mask displayed more consistent results.

Conclusions

The mandibular body mask (mandible without teeth, alveolar bone, rami and condyles) is a reliable reference for 3D regional registration.

Biological predictors of mandibular asymmetries in children with mixed dentition

OBJECTIVES

The objective was to investigate the severity of skeletal mandibular asymmetry in children with mixed dentition and other factors associated with asymmetry.

METHOD

The study was cross sectional, with stratified sampling according to malocclusion type consisting of 205 subjects with mixed dentition (median 10, interquartile range 9-11 years). There were 59 subjects presenting Class II/1, 77 Class II/2, and 69 Class III. The mandibular asymmetry has been estimated from orthopantomograms using the Habets' method and the dental maturation by Demirjian's method. The sagittal skeletal relationship and facial growth pattern were assessed from lateral cephalograms.

RESULTS

Asymmetries in general, were not rare and were more present in the condylar height rather than in the height of the ramus. The highest severity of condylar asymmetry was in Class II/2 subjects (median of asymmetry index 7.3; 64% subjects exhibiting moderate and severe asymmetry), while the Class III subjects exhibited the highest severity of both ramus and total height asymmetry (2.1; 13% and 2.0; 15%, respectively). Multiple logistic regression unveiled male gender as the only predictor of moderate or significant overall asymmetry. Dental age, the difference between dental and chronological age, and facial growth pattern were not significant predictors of asymmetries.

DISCUSSION

Overall, asymmetries in mixed dentition cannot be considered rare; however, no strong relationships between asymmetry and observed biological factors were found.

Comparative analysis of the gonial angle on lateral cephalometric radiographs and panoramic radiographs

We measured the gonial angle (GA) on panoramic radiography (PR) and analyzed the correlation between the GA on PR and lateral cephalometric radiography (LCR). In total, 49 PR films and LCR films from dentate young adults were evaluated. Orthodontists plotted four points (articulare, menton, posterior gonion, and lower gonion) on the PR and carefully traced them. Using a protractor, two radiologists measured the GA on LCR images. A simultaneous experimental study of two dry skulls was performed to compare the GA on LCR and PR. The GA was slightly smaller on the PR of the dry mandible than on the LCR and tended to decrease continuously with magnitude toward the Frankfort horizontal plane. The mean GA was 115.1 ± 5.2° on PR and 122.2 ± 6.4° on the LCR. The values were highly correlated (Pearson product-moment correlation coefficient, 0.801). The GA on PR was nonsignificantly smaller than that measured on LCR. The difference may be due to head position, the inclination angle of the mandibular body, and/or the direction of the incident X-ray beam.

Mandibular asymmetry: a proposal of radiographic analysis with public domain software

Objective

This preliminary study aimed to propose a new analysis of digital panoramic radiographs for a differential diagnosis between functional and morphological mandibular asymmetry in children with and without unilateral posterior crossbite.

Methods

Analysis is based on linear and angular measurements taken from nine anatomic points, demarcated in sequence directly on digital images. A specific plug-in was developed as part of a larger public domain image processing software (ImageJ) to automate and facilitate measurements. Since panoramic radiographs are typically subject to magnification differences between the right and left sides, horizontal linear measurements were adjusted for greater accuracy in both sides by means of a Distortion Factor (DF). In order to provide a preliminary assessment of proposed analysis and the developed plug-in, radiographs of ten patients (5 with unilateral posterior crossbite and 5 with normal occlusion) were analyzed.

Results

Considerable divergence was found between the right and left sides in the measurements of mandibular length and position of condyles in patients with unilateral posterior crossbite in comparison to individuals with normal occlusion.

Conclusion

Although there are more effective and accurate diagnostic methods, panoramic radiography is still widespread, especially in emerging countries. This study presented initial evidence that the proposed analysis can be an important resource for planning early orthodontic intervention and, thus, avoid progression of asymmetries and their consequences.

Dental, skeletal asymmetries and functional characteristics in Class II subdivision malocclusions

Treatment outcomes of Angle Class II subdivision malocclusions may be compromised because of the uncertainty of the aetiology. Previous studies have reported controversial ideas about the origins, but the existence of a primary contributor still remains unknown. Functional factors have been mentioned as a probable cause, but until now, there have been no supporting data. This study was a cross-sectional investigation of the characteristics of Angle Class II subdivision malocclusion, including dental, skeletal and functional factors, by comparison of the subdivision group and the normal occlusion group. The evaluations of dental and skeletal asymmetries of both groups were carried out by cone-beam computed tomography (CBCT) and analysis of dental casts. The functional deviations were evaluated by cast mounting and measuring. In the subdivision group, the asymmetric position of the glenoid fossa was found to be the most significant skeletal asymmetry. No dentoalveolar asymmetry was found in this group. The most important finding was that, in subdivision malocclusions, functional deviation resulting in pseudoasymmetry occurred in 32.86% of the study participants. This deviation is probably related to the disharmonious arch width between maxillary and mandibular dental arches in the premolar section. The origin of Angle Class II subdivision malocclusion is multifactorial, with dental, skeletal and functional factors included. Functional deviation occurs, probably due to dental arch width disharmony. Asymmetric position of the glenoid fossa may account for most of the skeletal asymmetry.

Comparison of gonial angle determination from cephalograms and orthopantomogram

Introduction:

Gonial angle is an important parameter of the craniofacial complex giving an indication about the vertical parameters and symmetry of the facial skeleton. Both orthopantomogram (OPG) and lateral cephalograms can be used for the measurement of gonial angle. Because of the superimpositions seen on lateral cephalograms, reliable measurement of the gonial angle becomes difficult. The aim of the present study is to check the possible application and reliability of OPG for gonial angle determination by clarifying whether there is any significant difference between the determination of gonial angle from OPG and cephalogram.

Materials and Methods:

Gonial angle measurements were made on lateral cephalograms and orthopantomograms of 98 patients - 44 males (mean age 25.9 years) and 54 females (mean age 21.3 years), and compared using Statistical Package for Social Sciences.

Results:

One-way analysis of variance demonstrated no significant differences between the values of gonial angles determined by lateral cephalogram and panoramic radiography. Pearson correlation showed a high correlation between cephalometric and OPG gonial angle value.

Conclusion:

Panoramic radiography can be used to determine the gonial angle as accurately as a lateral cephalogram. For determination of the gonial angle, an OPG may be a better choice than a lateral cephalogram as there are no interferences due to superimposed images of anatomical structures as in a lateral cephalogram. Thus, the present study substantiates the possibility of enhancing the clinical versatility of the panoramic radiograph, which is an indispensable tool for dental diagnosis.

Longitudinal evaluation of dental arch asymmetry in Class II subdivision malocclusion with 3-dimensional digital models

INTRODUCTION

Class II subdivision malocclusions with their asymmetric occlusal relationships often pose treatment difficulties. The aim of this study was to evaluate the longitudinal changes of dental arch asymmetry in untreated subjects with Class II subdivision malocclusion.

METHODS

From 706 files from the University of Michigan Growth Study, longitudinal records of 17 untreated subjects with Class II subdivision malocclusion were included this study. Dental arch changes at 3 consecutive longitudinal intervals, defined by the cervical vertebral maturation method, were analyzed on digital dental models. The average ages of the subjects were 12.4, 15.1, and 19.1 years at the 3 time periods, respectively. Maxillary and mandibular reference lines were constructed and used for the intra-arch asymmetry measurements. The Friedman test and analysis of variance with repeated measures were used to determine dental arch asymmetries at the P <0.05 level.

RESULTS

All subjects were found to have a type 1 Class II subdivision malocclusion characterized by distal positioning of the mandibular first molar on the Class II side. No statistically significant intra-arch asymmetry changes were found for the maxillary and mandibular dental arches in any time period. Between the baseline and the final follow-up, the data indicated decreases in maxillary and mandibular intercanine arch widths and arch lengths symmetrically.

CONCLUSIONS

The results of this study indicate that the dental arch asymmetry in patients with Class II subdivision malocclusions did not improve or worsen with growth.

Class II subdivision treatment with the Herbst appliance

OBJECTIVE

To assess the effectiveness of Class II subdivision Herbst nonextraction treatment and its short-term stability retrospectively.

MATERIALS AND METHODS

Twenty-two Class II subdivision (SUB: right-left molar difference ≥0.75 cusp width) and 22 symmetric Class II patients (SYM: ≥0.75 cusp width bilaterally) were matched according to gender and pretreatment handwrist radiographic stage. The mean treatment duration of the Herbst and subsequent multibracket phase was 8 months and 14 months, respectively. The mean retention period amounted to 36 months. Dental casts from before treatment (T1), after Herbst treatment (T2), after Multibracket treatment (T3), and after retention (T4) were evaluated.

RESULTS

A bilateral Class I or super Class I molar relationship was seen in 72.7% (SUB) and 77.3% (SYM) at T3. The corresponding values at T4 were 63.7% (SUB) and 72.7% (SYM). A unilateral or bilateral Class III molar relationship was more frequent in the SUB group (T3: +4.6%; T4: +13.6%). For overjet, similar mean values were seen in both groups after treatment (T3: SUB, 2.7 mm; SYM, 2.3 mm) and after retention (T4: SUB, 3.0 mm; SYM, 3.4 mm). This was also true for the midline shift (T3: SUB, -0.4 mm; SYM, 0.0 mm; T4: SUB, -0.3 mm; SYM, 0.0 mm).

CONCLUSION

Class II subdivision Herbst treatment was successful similarly to symmetric Class II Herbst treatment. However, a slight overcompensation of the molar relationship (Class III tendency) was more frequent in the subdivision patients (original Class I side).

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.

Tratamento ortodôntico-cirúrgico da assimetria facial esquelética: relato de caso

INTRODUÇÃO: as assimetrias faciais representam um desequilíbrio entre as estruturas esqueléticas homólogas da face. A maioria das pessoas apresenta algum grau de assimetria facial, pois é rara a condição de perfeita simetria. Todavia, somente quando é perceptível aos olhos do paciente, essa assimetria passa a ser relevante. Em tal condição, a correção ortocirúrgica ou o tratamento ortodôntico são possibilidades normalmente adotadas. OBJETIVO: o presente trabalho, baseado em uma revisão de literatura, é ilustrado por um caso clínico cujo tratamento consistiu em cirurgia ortognática Le Fort I para avanço e rotação da maxila e, na mandíbula, o tratamento foi conservador. CONCLUSÃO: o conhecimento da queixa principal e da expectativa do paciente e exames de diagnóstico bem realizados são itens importantes na decisão do plano de tratamento e no sucesso do resultado final.

Three-dimensional quantification of facial symmetry in adolescents using laser surface scanning

Laser scanning is a non-invasive method for three-dimensional assessment of facial morphology and symmetry. The aim of this study was to quantify facial symmetry in healthy adolescents and explore if there is any gender difference. Facial scans of 270 subjects, 123 males and 147 females (aged 15.3 ± 0.1 years, range 14.6-15.6), were randomly selected from the Avon Longitudinal Study of Parents and Children. Facial scans were processed and analysed using in-house developed subroutines for commercial software. The surface matching between the original face and its mirror image was measured for the whole face, upper, middle, and lower facial thirds. In addition, 3 angular and 14 linear parameters were measured. The percentage of symmetry of the whole face was significantly lower in males (53.49 ± 10.73 per cent) than in females (58.50 ± 10.27 per cent; P < 0.01). There was no statistically significant difference in the amount of symmetry among facial thirds within each gender (P > 0.05). Average values of linear parameters were less than 1 mm and did not differ significantly between genders (P > 0.05). One angular parameter showed slight lip line asymmetry in both genders. Faces of male 15-year-old adolescents were less symmetric than those of females, but the difference in the amount of symmetry, albeit statistically significant, may not be clinically relevant. Upper, middle, and lower thirds of the face did not differ in the amount of three-dimensional symmetry. Angular and linear parameters of facial symmetry did not show any gender difference.

A preliminary anatomical study on the association of condylar and occlusal asymmetry

The aim of this study was to test the hypothesis that condylar and occlusion asymmetry are not associated. For each of 22 skulls, the asymmetry of condyles was graded by one examiner and the asymmetry of occlusion by another examiner, both blinded to each other's evaluation, as 0 = symmetrical, 1 = mild asymmetrical and 2 = severe asymmetrical. There were 18 condyles graded the same as to their occlusion, but in four, the grades differed by one degree. Nine were graded symmetrical, seven were mild, and six were graded severely asymmetrical condyles. The corresponding figures for occlusion were: 10 were graded symmetrical, seven were graded mildly asymmetrical, and five were graded severely asymmetrical occlusion. The relation between occlusion and condylar asymmetry was tested using Goodman-Kruskal's gamma and was found to be 0.970 (p < 0.001). The null hypothesis was not supported. The results indicate that asymmetry of occlusion and condyles are associated, which indicates the need for further studies on larger samples, and in vivo studies.

Skeletal and dental asymmetries in Class II subdivision malocclusions using cone-beam computed tomography

INTRODUCTION

The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography.

METHODS

Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups.

RESULTS

Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side.

CONCLUSIONS

The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors.

Association between mandibular asymmetry and occlusal asymmetry in young adult males with class III malocclusion

OBJECTIVE

Our aim was to assess the association between mandibular asymmetry and sagittal and transverse occlusal asymmetry in young adult males with class III malocclusion. Our hypotheses were that (1) mandibular asymmetry increases with increasing mandibular length and (2) occlusal asymmetry is correlated with mandibular asymmetry.

MATERIAL AND METHODS

On lateral cephalograms of 54 subjects, skeletal class and mandibular length were measured. Mandibular asymmetry was evaluated on orthopantomograms as right-left difference between condylar or ramus heights. Occlusal asymmetry was assessed on dental casts by differences between right and left canine and molar relationship, anterior and posterior crossbite as well as midline deviation.

RESULTS

Mandibular asymmetry was significantly correlated with sagittal and transverse occlusal asymmetry (p < 0.05), but not with mandibular length (p > 0.05). Condylar asymmetry due to a longer condyle on one side was correlated with asymmetric aggravation of canine and molar class III on the ipsilateral side (r = -0.53 and -0.62, respectively). In contrast, ramus asymmetry was related to contralateral aggravation of canine and molar class III relationships (r = 0.27 and 0.29, respectively). Correlations existed between asymmetry in total height of the condyle and ramus and asymmetric aggravation of anterior crossbite (r = -0.33), posterior crossbite (r = -0.30) and lower midline deviation (r = -0.27) to the contralateral side (p < 0.05).

CONCLUSIONS

Mandibular asymmetry is associated with occlusal asymmetry, especially in the sagittal plane. Condylar asymmetry had 28% and 38% of variance in common with sagittal canine and molar asymmetry, respectively. Asymmetry in total height of the condyle and ramus was related to transverse occlusal asymmetry.

Mandibular asymmetry in cleft lip and palate patients

The aims of this study were to evaluate condylar, ramal, and condylar plus ramal mandibular vertical asymmetry in a group of cleft lip and palate (CLP) patients and compared with subjects with a 'normal' occlusion. Mandibular asymmetry index (condylar, ramal, and condylar plus ramal) and gonial angle measurements were examined on panoramic radiographs. The study groups comprised 20 unilateral cleft lip and palate (UCLP) patients (10 males and 10 females; mean age 13.03 +/- 3.33 years), 20 bilateral cleft lip and palate (BCLP) patients (10 males and 10 females; mean age 13.73 +/- 3.53 years), and a control group of 20 subjects (9 males and 11 females; mean age 14.35 +/- 2.46 years) with a normal occlusion. Kruskal-Wallis one-way analysis of variance was used to determine statistically significant differences between the groups for condylar, ramal, and condylar plus ramal asymmetry index measurements at the 95 per cent confidence interval. None of the investigated groups showed statistically significant gender differences for posterior vertical height measurements (P > 0.05). Asymmetry indices were similar, with no statistically significant differences found in any of the groups. However, gonial angle showed statistically significant differences (P < 0.05) in the UCLP group and condylar height (CH) in the BCLP patients (P < 0.001). Except for CH measurement in the BCLP group, CLP patients have symmetrical mandibles when compared with a normal occlusion sample.