Condylar volume and surface in Caucasian young adult subjects

Assessment of condylar morphology and position using MSCT in an Asian population

OBJECTIVES

The purpose of the present study was to investigate the volume, surface, morphometric index (MI), and position of the condyle in a normal population by applying Mimics 17.0 software. Then, the difference between left and right sides, sex, and age can be explored, which will contribute to establish the reference value of condylar morphology and position in normal individuals, and help us to study characteristics of condylar morphology and position in abnormal individuals.

MATERIALS AND METHODS

Three-hundred subjects were enrolled in our study from the radiology department of Shanghai Jiao Tong University Affiliated Sixth People's Hospital. They were divided into three groups according to the age: group 1 (18-24 years old), group 2 (25-34 years old), and group 3 (35-44 years old). Each group included 100 subjects (with 50 males and 50 females). They were examined using multislice computed tomography (MSCT) after that. All images of condyle were reconstructed by Mimics 17.0 software, so as to measure the volume, surface, and MI of condyle, and to analyze the position of condyle in the articular fossa by means of joint spaces.

RESULTS

The differences of condylar volume, surface, and MI between left and right sides were not obvious (P > 0.05). The condylar volume and surface were greater in males than females (P < 0.05), while their condylar MI existed no difference (P > 0.05). No statistical differences were found in volume and surface among three age groups. However, the MI of group 1 was statistically lower than that of group 3 (P < 0.05). On the other hand, no significant differences were found between left and right condylar position (P > 0.05). Nevertheless, there were significant differences of condylar position regarding the gender and age (P < 0.05).

CONCLUSIONS

This study showed no significant differences in condylar morphology and position between left and right sides, but factors of gender and age were proven to have a certain influence on the morphology and position of the condyle. This information can be clinically useful in establishing the diagnostic criteria for condylar morphology and position in the normal Asian population.

CLINICAL RELEVANCE

Examination of condylar morphology and position is important for evaluating the abnormalities and bony changes that affect the temporomandibular joint (TMJ). So, this will be conducive to the diagnosis and the evaluation of therapeutic effect of temporomandibular joint diseases. Also, it is important to evaluate these indexes prior to commencing orthodontic treatment, because TMJ abnormalities play a critical role in orthodontic treatment planning.

Relationships between temporomandibular joint disk displacements and condylar volume

OBJECTIVES

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Accuracy and Reliability of Cone-Beam Computed Tomography for Linear and Volumetric Mandibular Condyle Measurements. A Human Cadaver Study

The accuracy of Cone-Beam Computed Tomography (CBCT) on linear and volumetric measurements on condyles has only been assessed on dry skulls. The aim of this study was to evaluate the reliability and accuracy of linear and volumetric measurements of mandibular condyles in the presence of soft tissues using CBCT. Six embalmed cadaver heads were used. CBCT scans were taken, followed by the extraction of the condyles. The water displacement technique was used to calculate the volumes of the condyles and three linear measurements were made using a digital caliper, these measurements serving as the gold standard. Surface models of the condyles were obtained using a 3D scanner, and superimposed onto the CBCT images. Condyles were isolated on the CBCT render volume using the surface models as reference and volumes were measured. Linear measurements were made on CBCT slices. The CBCT method was found to be reliable for both volumetric and linear measurements (CV < 3%; CCI > 0.90). Highly accurate values were obtained for the three linear measurements and volume. CBCT is a reliable and accurate method for taking volumetric and linear measurements on mandibular condyles in the presence of soft tissue, and so a valid tool for clinical diagnosis.

Cone-beam volumetric imaging in craniofacial medicine

With the development of X-ray computed tomography (CT) in the 1960s and its first use for clinical studies in 1972 by Sir Godfrey Hounsfield, radiological tomography attained widespread use and today is one of the essential imaging techniques in medical radiology. It is a technically mature and clinically widely accepted method and complements classical X-ray panoramic radiography in many areas. The technology is frequently used in craniofacial radiology, because of its characteristic low radiation dose, high spatial resolution and lower cost compared with CT. The aim of this work was to describe the principles of cone beam computed tomography, to make a brief description of the existing devices, to present briefly the use of 3D diagnosis in craniofacial medicine.

Temporomandibular Joint Anatomy Assessed by CBCT Images

Aim. Since cone beam computed tomography (CBCT) has been used for the study of craniofacial morphology, the attention of orthodontists has also focused on the mandibular condyle. The purpose of this brief review is to summarize the recent 3D CBCT images of mandibular condyle. Material and Methods. The eligibility criteria for the studies are (a) studies aimed at evaluating the anatomy of the temporomandibular joint; (b) studies performed with CBCT images; (c) studies on human subjects; (d) studies that were not clinical case-reports and clinical series; (e) studies reporting data on children, adolescents, or young adults (data from individuals with age ≤ 30 years). Sources included PubMed from June 2008 to June 2016. Results. 43 full-text articles were initially screened for eligibility. 13 full-text articles were assessed for eligibility. 11 articles were finally included in qualitative synthesis. The main topics treated in the studies are the volume and surface of the mandibular condyle, the bone changes on cortical surface, the facial asymmetry, and the optimum position of the condyle in the glenoid fossa. Conclusion. Additional studies will be necessary in the future, constructed with longitudinal methodology, especially in growing subjects. The limits of CBCT acquisitions are also highlighted.

The 3D Tele Motion Tracking for the Orthodontic Facial Analysis

Aim. This study aimed to evaluate the reliability of 3D-TMT, previously used only for dynamic testing, in a static cephalometric evaluation. Material and Method. A group of 40 patients (20 males and 20 females; mean age 14.2 ± 1.2 years; 12–18 years old) was included in the study. The measurements obtained by the 3D-TMT cephalometric analysis with a conventional frontal cephalometric analysis were compared for each subject. Nine passive markers reflectors were positioned on the face skin for the detection of the profile of the patient. Through the acquisition of these points, corresponding plans for three-dimensional posterior-anterior cephalometric analysis were found. Results. The cephalometric results carried out with 3D-TMT and with traditional posterior-anterior cephalometric analysis showed the 3D-TMT system values are slightly higher than the values measured on radiographs but statistically significant; nevertheless their correlation is very high. Conclusion. The recorded values obtained using the 3D-TMT analysis were correlated to cephalometric analysis, with small but statistically significant differences. The Dahlberg errors resulted to be always lower than the mean difference between the 2D and 3D measurements. A clinician should use, during the clinical monitoring of a patient, always the same method, to avoid comparing different millimeter magnitudes.

3-Dimensional CBCT analysis of mandibular asymmetry in unilateral condylar hyperplasia

PURPOSE

Three-dimensional quantification of asymmetry in UCH has not been reported yet, but would be useful for diagnosing and evaluating the degree of deformity in this disease. It enables profound decision-making and timing of surgery. Unilateral condylar hyperplasia (UCH) can subjectively be classified in hemimandibular elongation (HE), hemimandibular hyperplasia (HH) and a combination of these two (hybrid form). The main purpose of this study was to quantify mandibular asymmetry in UCH patients with a reliable and reproducible method. Secondly, it was evaluated whether the existing classification can be confirmed.

MATERIALS AND METHODS

37 UCH-patients with progressive mandibular asymmetry, supported by a positive bone scan and/or such clinical progression that condylectomy was performed, were included in this retrospective study. A group of healthy subjects, matched for age and gender, was used as the control group. Cone-beam computed tomography (CBCT) scans were imported in Maxilim^® software. Each mandibular half was divided into three skeletal segments (condyle, ramus, and body). Linear and volumetric measurements were calculated for these skeletal units on the affected and unaffected side, for both patients and controls.

RESULTS

Significant differences between affected and unaffected sides in the patient group were found in condylar, ramus, and body segments for linear (p < 0.01) as well as for volumetric quantitative measurements (p < 0.0040). A mean linear difference between affected and unaffected sides in the condylar region of the UCH patient group was found of 3.6 mm (sd 2.9) versus 0.2 mm (sd 1.5) in controls. For volumetric measurements there was a mean difference between the left and right condyle of 718 mm³ (sd 638) in the patient group versus 8 mm³ (sd 225) difference in the control group. The condyle was the most affected segment. Differences between sides were significantly larger in the patient group than in the control group (p < 0.001). It was not possible to objectify differences between HE and HH.

CONCLUSION

CBCT is a useful and accurate modality for quantification and evaluation of mandibular asymmetry in UCH. It enables objective monitoring. The existing classification in HE and HH could not be confirmed.

Novel 3-dimensional analysis to evaluate temporomandibular joint space and shape

INTRODUCTION

The purpose of this study was to present and validate a novel semiautomated method for 3-dimensional evaluation of the temporomandibular joint (TMJ) space and condylar and articular shapes using cone-beam computed tomographic data.

METHODS

The protocol for 3-dimensional analysis with the Checkpoint software (Stratovan, Davis, Calif) was established by analyzing cone-beam computed tomographic images of 14 TMJs representing a range of TMJ shape variations. Upon establishment of the novel method, analysis of 5 TMJs was further repeated by several investigators to assess the reliability of the analysis.

RESULTS

Principal components analysis identified 3 key components that characterized how the condylar head shape varied among the 14 TMJs. Principal component analysis allowed determination of the minimum number of landmarks or patch density to define the shape variability in this sample. Average errors of landmark placement ranged from 1.15% to 3.65%, and none of the 121 landmarks showed significant average errors equal to or greater than 5%. Thus, the mean intraobserver difference was small and within the clinically accepted margin of error. Interobserver error was not significantly greater than intraobserver error, indicating that this is a reliable methodology.

CONCLUSIONS

This novel semiautomatic method is a reliable tool for the 3-dimensional analysis of the TMJ including both the form and the space between the articular eminence and the condylar head.

[Research on condylar morphology in patients with prolonged unilateral posterior teeth loss with cone beam computed tomography]

OBJECTIVE

This study aimed at using cone beam computed tomography (CBCT) to study the influence ofprolonged unilateral posterior teeth loss on bilateral condylar morphology.

METHODS

The CBCT images of 30 patients withprolonged unilateral posterior teeth loss and 30 healthy people as controls were corrected. Mimics 15.0 software was used tomeasure volume, area, distance, and bone density of condyle. The results were statistically analyzed.

RESULTS

The volumeand bone density of condylar head and the entire condyle on missing teeth side were less than the contralateral side (P<0.05).The area and bone density of condylar transverse plane were greater than the contralateral side (P<0.05).

CONCLUSION

After prolonged unilateral posterior teeth loss, adaptive reconstruction occurs in the bilateral condyles, and condyle of missing teethside is smaller than the contralateral side.

Characteristics of temporomandibular joint in patients with temporomandibular joint complaint

INTRODUCTION

This study was to investigate whether there was statistical difference between the bilateral temporomandibular joint (TMJ) in patients with unilateral TMJ pain or joint sounds, using cone beam computed tomography (CBCT).

METHODS

TMJ CBCT images of 123 cases were used to preliminarily determine the indicators suitable for the measuring method. TMJ CBCT image reconstruction was performed and 19 indicators were measured. Thirty-six cases without TMJ complaint served as controls. The comparison of bilateral TMJs was analyzed by paired t-test to find out the indicators without statistical significance. Twenty-nine patients with unilateral TMJ pain or joint sounds who underwent CBCT at the hospital were enrolled for the comparative study. The measured values were analyzed by paired t-test to determine the indicators with statistical difference.

RESULTS

In the control group, only radius value of bilateral TMJ was different statistically (P < 0.05). In the TMJ complaint group, the vertical 60° joint space of the bilateral TMJ was statistically different (P < 0.05) and the rest of the measured values showed no statistical difference.

CONCLUSIONS

In the patients with unilateral TMJ pain or joint sounds, the vertical 60° joint space of the symptomatic side was significantly increased comparing with the asymptomatic side.

Temporomandibular joint diagnostics using CBCT

The present review will give an update on temporomandibular joint (TMJ) imaging using CBCT. It will focus on diagnostic accuracy and the value of CBCT compared with other imaging modalities for the evaluation of TMJs in different categories of patients; osteoarthritis (OA), juvenile OA, rheumatoid arthritis and related joint diseases, juvenile idiopathic arthritis and other intra-articular conditions. Finally, sections on other aspects of CBCT research related to the TMJ, clinical decision-making and concluding remarks are added. CBCT has emerged as a cost- and dose-effective imaging modality for the diagnostic assessment of a variety of TMJ conditions. The imaging modality has been found to be superior to conventional radiographical examinations as well as MRI in assessment of the TMJ. However, it should be emphasized that the diagnostic information obtained is limited to the morphology of the osseous joint components, cortical bone integrity and subcortical bone destruction/production. For evaluation of soft-tissue abnormalities, MRI is mandatory. There is an obvious need for research on the impact of CBCT examinations on patient outcome.

No differences in morphological characteristics between hyperplastic condyle and class III condyle

The aim of this research was to compare the condylar morphology of patients with unilateral condylar hyperplasia (UCH) and patients with a class III skeletal relationship using cone beam computed tomography (CBCT). A prospective study was conducted on patients with facial asymmetry attending the division of oral and maxillofacial surgery of the study university in Chile. Fifteen patients with UCH and 15 with a class III skeletal relationship were selected. Linear measurements of the condylar processes were obtained at a scale of 1:1 using the software Ez3D Viewer Plus. Analysis of variance (ANOVA) and the paired t-test were used, considering P<0.05. Patients with UCH presented statistical differences between the hyperplastic condyle and non-hyperplastic condyle for anteroposterior and mediolateral diameters, condylar neck length, and ramus height. Patients with a class III skeletal relationship showed no differences between the right and left sides; the morphology of their condyles was similar to the condyles with hyperplasia and presented statistical differences when compared with the non-hyperplastic condyles (one-way ANOVA, P<0.05). The condylar morphology of UCH patients could be related to the development of a class III skeletal relationship. These findings provide an insight into the possibility of some class III patients presenting bilateral condylar hyperplasia.

Effect of untreated and treated temporomandibular joint arthritis on mandibular volume development in growing rabbits

OBJECTIVES

The goal of this work was to investigate the volume development of the mandible in growing rabbits with bilaterally induced temporomandibular joint (TMJ) arthritis that was either left untreated or treated with the tumor necrosis factor-alpha (TNF-α) antagonist etanercept.

METHODS

A total of 18 New Zealand White rabbits aged 8 weeks were randomized to three groups of 6 animals each. Two of these groups were used as arthritis groups by sensitizing the 12 animals to ovalbumin (OA) at 10 weeks, followed by intraarticular OA injections to induce bilateral TMJ arthritis and repeating these injections every 3 weeks to maintain the inflammation. One of the two arthritis groups was treated by weekly subcutaneous etanercept injections, whereas the other group was left untreated. The remaining 6 animals served as controls. Maxillofacial CT scans were obtained at 3-week intervals (from week 10 of the rabbits' lives to the end of the experiment at 22 weeks) to volumetrically track the development of the mandibles after segmentation.

RESULTS

The mandibles did not grow at a continuous rate, but the rate of development was found to decrease in all groups over the course of the study (weeks 10-22). The most extensive volume increases were noted during weeks 10-13. Severe growth deficiencies, especially of the condylar processes, were observed in the arthritis group not receiving treatment. The arthritis group treated with etanercept showed better rates of growth without, however, reaching the normal range of the control group.

CONCLUSION

Antigen-induced TMJ arthritis was found to involve severe problems of growth similar to those in juvenile idiopathic arthritis. Etanercept can improve the volume development but does not reestablish an entirely normal rate of growth.

Assessment of condyle and glenoid fossa morphology using CBCT in South-East Asians

Introduction

Proper imaging allows practitioners to evaluate an asymptomatic tempormandibular joint (TMJ) for potential degenerative changes prior to surgical and orthodontic treatment. The recently developed cone-beam computed tomography (CBCT) allows measurement of TMJ bony structures with high accuracy. A study was undertaken to determine the morphology, and its variations, of the mandibular condyle and glenoid fossa among Malay and Chinese Malaysians.

Methods

CBCT was used to assess 200 joints in 100 subjects (mean age, 30.5 years). i-CAT CBCT software and The Mimics 16.0 software were employed to measure the volume, metrical size, position of each condyle sample and the thickness of the roof of the glenoid fossa (RGF).

Results

No significant gender differences were noted in thickness of the RGF and condylar length; however condylar volume, width, height and the joint spaces were significantly greater among males. With regards to comparison of both TMJs, the means of condylar volume, width and length of the right TMJ were significantly higher, while the means of the left condylar height and thickness of RGF were higher. When comparing the condylar measurements and the thickness of RGF between the two ethnic groups, we found no significant difference for all measurements with exception of condylar height, which is higher among Chinese.

Conclusion

The similarity in measurements for Malays and Chinese may be due to their common origin. This information can be clinically useful in establishing the diagnostic criteria for condylar volume, metrical size, and position in the Malaysian East Asians population.

Quantitative measurements of the articular areas of mandibular condyles with temporomandibular joint disorders using magnetic resonance imaging

OBJECTIVE

The authors sought to clarify the variation in the condylar anterior functional surface (AFS) of patients with temporomandibular joint (TMJ) disorders using quantitative measurements by magnetic resonance imaging (MRI).

METHODS

MR images of 68 joints (2 males, 32 females) were used. The subjects were classified into three groups: with/without defects of cortical bone groups and a combination group without defects. The AFS was measured as the length between the protrusive point and the apex of the condyle on MRI (4-mm-thick slices), and the quad value of the length was defined as the area on the slice. The summed quad values of all slices were used as the AFS area. Differences in the areas among the three groups were compared by one-way analysis of variance (ANOVA).

RESULTS

The non-defect group had significantly larger AFS areas than the defect group.

CONCLUSIONS

Quantitative measurement on MR images clarified the changes in the condylar sagittal appearance.

Condylar response to functional therapy with Twin-Block as shown by cone-beam computed tomography

OBJECTIVE

To evaluate the condylar changes through cone-beam computed tomography (CBCT) images in patients treated with Twin-Block functional appliance.

MATERIALS AND METHODS

In this retrospective study, CBCT images of 30 patients who were treated with the Twin-Block appliance were used. Mandible was segmented and pretreatment and posttreatment (T0 and T1) condylar volume was compared. The angle between sella-nasion-Point A (SNA), angle between sella-nasion-Point B (SNB), angle between Point A-nasion-Point B (ANB), midfacial length (Co-A), mandibular length (Co-Gn), and the distances from right condylion to left condylion (CoR-CoL) were also measured on three-dimensional images. Differences were analyzed with Wilcoxon signed rank tests, and Mann-Whitney U-tests were used to compare the scores of male and female participants. Significance was set at P < .05.

RESULTS

In this study, a decrease in SNA and ANB (P < .05 and P < .01, respectively) and an increase in SNB (P < .01) were found. Additionally, CoR-CoL, Co-Gn, and condylar volume increased at both the left and right sides (P < .01). However, increase at Co-A was not statistically significant (P > .05). Comparison of differences by sex was not statistically significant for all measurements (P > .05).

CONCLUSION

Twin-Block appliance increases condylar volume, mandibular length, and intercondylar distance by stimulating growth of condyle in an upward and backward direction.

Mandibular asymmetry: a three-dimensional quantification of bilateral condyles

INTRODUCTION

The shape and volume of the condyle is considered to play an important role in the pathogenesis of the mandibular deviation. Curvature analysis is informative for objectively assess whether the shape of the condyles matches that of the glenoid fossa. In this study, a three-dimensional (3-D) quantification of bilateral asymmetrical condyles was firstly conducted to identify the specific role of 3-D condylar configuration for mandibular asymmetry.

METHODS

55 adult patients, 26 males (26 ± 5 yrs) and 29 females (26 ± 5 yrs), diagnosed with mandibular asymmetry were included. The examination of deviation of chin point, deviation of dental midlines, inclination of occlusal plane, and depth of the mandibular occlusal plane were conducted. After the clinical investigation, computed tomography images from the patients were used to reconstruct the 3-D mandibular models. Then the condylar volume, surface size, surface curvature and bone mineral density were evaluated independently for each patient on non-deviated and deviated sides of temporomandibular joint.

RESULTS

Both the condylar surface size and volume were significantly larger on deviated side (surface size: 1666.14 ± 318.3 mm2, volume: 1981.5 ± 418.3 mm3). The anterior slope of the condyle was flatter (0.12 ± 0.06) and the posterior slope (0.39 ± 0.08) was prominently convex on the deviated side. The corresponding bone mineral density values were 523.01 ±118.1 HU and 549.07 ±120. 6 HU on anterior and posterior slopes.

CONCLUSIONS

The incongruence presented on the deviated side resulted in a reduction in contact areas and, thus, an increase in contact stresses and changes of bone density. All aforementioned results suggest that the difference existing between deviated and non-deviated condyles correlates with facial asymmetrical development. In mandibular asymmetry patients, the 3-D morphology of condyle on deviated side differ from the non-deviated side, which indicates the association between asymmetrical jaw function and joint remodeling.

The effect of computed tomographic scanner parameters and 3-dimensional volume rendering techniques on the accuracy of linear, angular, and volumetric measurements of the mandible

OBJECTIVES

This study investigates the effect of scanning parameters on the accuracy of measurements from three-dimensional (3D), multi-detector computed tomography (MDCT) mandible renderings. A broader range of acceptable parameters can increase the availability of computed tomographic (CT) studies for retrospective analysis.

STUDY DESIGN

Three human mandibles and a phantom object were scanned using 18 combinations of slice thickness, field of view (FOV), and reconstruction algorithm and 3 different threshold-based segmentations. Measurements of 3D computed tomography (3DCT) models and specimens were compared.

RESULTS

Linear and angular measurements were accurate, irrespective of scanner parameters or rendering technique. Volume measurements were accurate with a slice thickness of 1.25 mm, but not 2.5 mm. Surface area measurements were consistently inflated.

CONCLUSIONS

Linear, angular, and volumetric measurements of mandible 3D MDCT models can be confidently obtained from a range of parameters and rendering techniques. Slice thickness is the primary factor affecting volume measurements. These findings should also apply to 3D rendering using cone-beam CT (CBCT).

Three-dimensional condylar positions and forms associated with different anteroposterior skeletal patterns and facial asymmetry in Chinese adolescents

OBJECTIVE

To evaluate the association of condylar asymmetry and chin position with different anteroposterior skeletal patterns using three-dimensional models reconstructed from cone-beam computed tomography (CBCT) images.

MATERIALS AND METHODS

CBCT scans of 123 Chinese adolescents (aged 11-15 years, 68 girls and 55 boys) with 64 skeletal Class I, 46 Class II and 13 Class III were selected from scans of patients attending the orthodontic clinic. The condyles of the subjects were reconstructed bilaterally and 25 linear, angular and volumetric measurements were performed to evaluate the asymmetry of the condyles and position of the chin. The proportions of condylar asymmetry in the different skeletal groups were calculated by the absolute difference value between the left and right sides to the smaller side value. One-way analysis of variance and Pearson's correlations were used to analyse the data.

RESULTS

The values for RV, RCL, LCH, RCH, LCGM, RCGM, LCo-Me and RCo-Me were significantly different among the three skeletal groups (p < 0.05). There were significant positive correlations between Pog-Ss and Co-Sh, Co-Me in the Class I and II groups (p < 0.05). Asymmetries for Co-Ss, Co-Sh, CP and SP between the left and right condyles exceeded a ratio of 20% for more than 30% of the subjects.

CONCLUSION

Condylar asymmetry varied significantly among the three skeletal groups, with the vertical position of the condyle (Co-Sh) and height of the mandibular ramus (Co-Me) being significantly and positively related to the chin position.

The effect of slice thickness on the assessment of bone defect volumes by the Cavalieri principle using cone beam computed tomography

The purpose of this study was to investigate the possible effects of section thickness on volume estimations obtained by cone beam computed tomography. Intraosseal cavities representing bone defects on vestibular sides of the two dry sheep mandibles were scanned by a cone beam computed tomography system. Consecutive sections at 0.2, 0.6, 1, 1.4, and 2.2 mm thickness were used to estimate the volumes of the cavities using the Cavalieri principle of stereological methods. Estimated volumes are then compared with the volumes obtained by the Archimedean principle. In 0.2-, 0.6-, and 1-mm-thick slices, the volumes estimated by the Cavalieri principle did not differ from the volumes by the Archimedean principle (p > 0.05). The 0.2 mm slice-thickness group had the highest asymptotic significance value (p = 0.6). Although the thinnest slice appears to provide the most accurate values, slice thickness up to 1 mm can be chosen for volume calculations on CBCT images.

TMJ imaging by CBCT: Current scenario

Radiographic examination forms an integral component of the clinical assessment routine in patients with temporomandibular joint disorders (TMJ). There are several imaging modalities to visualize the TMJ. Cone beam computed tomography (CBCT) is a developing technique that is being increasingly used in dentomaxillofacial imaging due to its relatively low-dose high-spatial-resolution characteristics. Research in TMJ imaging has been greatly inspired by the advent of CBCT. In this paper we aim to discuss the present scenario of the role of CBCT in TMJ imaging.

Do skeletal cephalometric characteristics correlate with condylar volume, surface and shape? A 3D analysis

Objective

The purpose of this study was to determine the condylar volume in subjects with different mandibular divergence and skeletal class using cone-beam computed tomography (CBCT) and analysis software.

Materials and methods

For 94 patients (46 females and 48 males; mean age 24.3 ± 6.5 years), resultant rendering reconstructions of the left and right temporal mandibular joints (TMJs) were obtained.

Subjects were then classified on the base of ANB angle the GoGn-SN angle in three classes (I, II, III) . The data of the different classes were compared.

Results

No significant difference was observed in the whole sample between the right and the left sides in condylar volume.

The analysis of mean volume among low, normal and high mandibular plane angles revealed a significantly higher volume and surface in low angle subjects (p < 0.01) compared to the other groups.

Class III subjects also tended to show a higher condylar volume and surface than class I and class II subjects, although the difference was not significant.

Conclusions

Higher condylar volume was a common characteristic of low angle subjects compared to normal and high mandibular plane angle subjects. Skeletal class also appears to be associated to condylar volume and surface.