Reliability and accuracy of a method for measuring temporomandibular joint condylar volume

Long-term evaluation of condylar positional and volumetric parameters and skeletal stability in Class III bimaxillary orthognathic surgery patients

This retrospective study examined long-term (4-5 years) condylar positional and volumetric changes and skeletal stability after bimaxillary orthognathic surgery in skeletal Class III patients. Pre-surgical (T0: 0.9 ± 1.1 months) and post-surgical (T1: 0.6 ± 0.7 months; T2: 12.8 ± 3.1 months; T3: 56.5 ± 6.5 months) cone beam computed tomography (CBCT) images of 22 patients were obtained. CBCT multiplanar reformation (MPR) images were generated, and three-dimensional (3D) condylar models were constructed and superimposed to compare changes in condylar volume from pre- to postoperative. Condylar position in the sagittal and coronal planes altered immediately after surgery; however at long-term follow-up, the condyles had returned to their pre-surgical position. The condyles remained slightly inwardly rotated at short-term (-2.6°, 95% confidence interval -3.5° to -1.7°) and long-term (-1.9°, 95% confidence interval -2.8° to -1.0°) follow-up. Changes in condylar volume were insignificant after surgery. Condylar positional changes had no effect on skeletal stability. However, patients with an increased face height prior to surgery and more retrusive jaw position postoperatively were more prone to condylar resorption. Surgical changes remained stable 4-5 years after surgery. In conclusion, condylar position changed insignificantly following surgical correction in Class III patients provided that the correct surgical technique was employed.

Temporomandibular Joint Space in Mandibular Prognathism

This study compared the temporomandibular joint (TMJ) space between patients with normal and prognathic mandibles. The study included a total of 68 Korean individuals, and the TMJ space was measured using computed tomography. Patients with normal SNB values (normal mandible) were classified into Group 1. Patients with high SNB values (prognathic mandibles) were categorized into Group 2. The TMJ space was defined as the distance between the condylar process and the mandibular fossa, and it was significantly different between Groups 1 and 2 (1.94±0.07 mm versus 1.50±0.05 mm, P< 0.01). This study confirmed that the TMJ space in patients with prognathic mandibles is narrower than that in patients with normal mandibles.

In-house three-dimensional printing for surgical planning: learning curve from a case series of temporomandibular joint and related disorders

Three-dimensional (3D) printed models can improve the understanding of the structural anatomic changes in cases of temporomandibular joint ankylosis and pseudoankylosis leading to closed jaw locking. Their use in pre-surgical planning and intraoperative guidance has been reported, contributing to the predictability and success of these surgery procedures, which can be quite complex, especially in small animal patients. The use and production of 3D tools and models remain challenging and are so far limited to institutions with high (economical and human) resources. This study aims to propose simplified workflows using open-source software to facilitate an in-house 3D printing process. To illustrate this, three cases of temporomandibular joint ankylosis and one of pseudoankylosis were reviewed, where in-house 3D printed models were used for client communication and surgical management. The 3D models were segmented from computed tomography and printed via stereolithography. They were used to support discussion with clients (n = 4), to allow surgeons to pre-surgical plan and practice (n = 4) and for intraoperative guidance during surgery (n = 2). Surgical cutting guides were produced in one case to improve precision and define more accurately osteotomy lines. It is essential to consider the initial time and financial investment required for establishing an in-house 3D printing production, particularly when there is a need to produce biocompatible tools, such as surgical cutting guides. However, efficient and streamlined workflows encourage the integration of this technology, by accelerating the printing process and reducing the steep learning curves, while open-source software enhances accessibility to these resources.

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

Background

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

Materials and Methods

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

Results

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

Conclusion

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

Appraisal of the Accuracy and Reliability of Cone-Beam Computed Tomography and Three-Dimensional Printing for Volumetric Mandibular Condyle Measurements of a Human Condyle

Background This study aims to evaluate the accuracy of volumetric measurements of three-dimensional (3D)-printed human condyles from cone-beam computed tomography (CBCT) in comparison to physical condyles using a water displacement test. Methodology A sample of 22 dry condyles was separated from the mandibular body by disc, mounted on a base made of casting wax, and scanned using the SCANORA (Scanora 3DX, Soredex, Finland) CBCT scanner. Subsequently, the projection data were reconstructed with the machine-dedicated OnDemand 3D (Cybermed Co., Seoul, Korea). The Standard Tessellation Language file was prepared for 3D printing using chitubox slicing software v1.9.1. Frozen water-washable gray resin was used for 3D printing. All condyles were printed using the same parameters and the same resin. The volumetric measurements were then performed using a customized modified pycnometer based on water volume and weight displacement. Volumetric measures were performed for both the physical human condyles and the 3D-printed replicas and the measurements were then compared. Results The volume of dry condyles using the water displacement method showed an average (±SD) of 1.925 ± 0.40 cm3. However, the volume of 3D-printed replicas using the water displacement method showed an average (±SD) of 2.109 ± 0.40 cm3. The differences in measurements were insignificant (p > 0.05), as revealed by an independent t-test. Conclusions Highly precise, accurate, and reliable CBCT for volumetric mandibular condyle was applied for measurements of a human condyle and 3D-printed replica. The modified pycnometer for volumetric measurements presented an excellent volumetric measure based on a simple water displacement device. The tested modified pycnometer can be applied in volumetric measurements in both 3D-printed and mandibular condyle. For best accuracy, the highest scanning resolution possible should be used. As it directly handles irregularly shaped solid objects in a non-destructive manner with a high level of precision and reliability, this 3D scanning approach may be seen as a superior alternative to the current measurement methods.

A Comparison of the Condyle and Articular Eminence in Asian Juvenile Idiopathic Osteoarthritis Patients with Unilateral and Bilateral TMJ Involvement: A Retrospective Case-Control Study

This study compared the condylar volume, length, and articular eminence (AE) characteristics of normal individuals to those with unilateral and bilateral juvenile idiopathic osteoarthritis (JOA). The 116 patients were divided into four groups: Control (n = 16), affected condyle of unilateral JOA (Aff-Uni) (n = 36), non-affected condyle of JOA (NonAff-uni) (n = 36), and bilateral JOA (Bilateral) (n = 28). The differences in condyle volume and length and AE were analyzed using ANOVA and Bonferroni post-hoc tests. The results showed that Bilateral had a significantly different condylar volume, especially in the condylar head (p < 0.01), specifically the middle, anterior, and medial parts (p < 0.05). Condylar length also differed among the groups, with differences observed between the control group and the other three groups, as well as between the bilateral group and the other three groups (p < 0.01). AE total volume differed between the control group and Aff-Uni. In the detailed comparison, Aff-Uni and NonAff-Uni were smaller than the control group in the posterior, lateral, and medial sections (p < 0.05). In conclusion, depending on the involvement of unilateral or bilateral JOA, there were differences in condylar volume and AE when compared to the normal control group. Therefore, a prognosis should be evaluated by distinguishing between patients with unilateral and bilateral JOA.

Assessment of mandibular asymmetry in different skeletal malocclusions and vertical patterns in adult individuals: A cone-beam computed tomography study

OBJECTIVES

The study aims to measure the mandibular condylar height (CH), ramus height (RH), total height (CH+RH), asymmetry index, and condylar volume (Cvol) in individuals with different anteroposterior and vertical skeletal discrepancies.

MATERIALS AND METHODS

The study sample consisted of 131 subjects (60 females and 71 males) with a mean age of 35.06 ± 12.79 years. Pre-existing CBCT images were divided into groups according to the anteroposterior and vertical skeletal discrepancies. The investigator analyzed the data using t-tests to assess the mandibular bilateral sides of the individuals and gender differences. The mean difference between groups was determined using a one-way analysis of variance (ANOVA). The Chi-square test was used to study the association between the asymmetry index and groups.

RESULTS

Each individual's bilateral sides exhibited statistically significant differences in CH, RH, and Cvol (P = 0.033, P = 0.039, P = 0.005, respectively), but not in CH+RH (P = 0.458). There were, however, statistically significant gender differences in CH+RH (P < 0.001). Skeletal Class III and hypodivergent groups revealed the highest linear and volumetric values compared to other groups. The asymmetry index was increased in CH (P = 0.006) and Cvol (P = 0.002) in skeletal Class II subjects.

CONCLUSIONS

Significant differences in CH, RH, and Cvol were found on the right and left sides of the same individual. This study found increased linear and volumetric values in males, skeletal Class III, and hypodivergent subjects. Class II individuals had an increased CH and Cvol asymmetry index. This study highlights in-depth knowledge of mandibular asymmetry, which is extremely important to achieve an accurate diagnosis and provide the best treatment outcome.

Analysis of the Volumetric Asymmetry of the Mandibular Condyles Using CBCT

Objectives

The aim of this study was to analyse volumetric asymmetries between the right and left condyles in relation to age, gender, and dental status.

Materials and methods

A retrospective analysis of 150 cone beam computed tomography (CBCT) scans was conducted. A single investigator performed the volumetric analysis of the CBCT scans using Vesalius 3D software. The volumetric data were analysed in relation to the gender, age, and dental status.

Results

The mean right condylar volume was significantly higher (P < .01) than the left condylar volume. Right and left condylar volumes were significantly higher (P < .01) in male study participants when compared to female study participants. There was no significant difference (P = .47) in the volumetric asymmetry between the male and female study participants. The volumetric asymmetry was significantly higher (P < .01) in the older age groups when compared to the younger age groups. The volumetric asymmetry was significantly higher (P < .01) in the partially and completely edentulous patients when compared to the dentate study participants. The condylar volume on the side having a partially edentulous area was significantly lower than the condylar volume of the contralateral dentate side (P < .001).

Conclusions

The volumetric asymmetry between the right and left condyle significantly increases with age and edentulousness. The result of the study encourages the clinicians to perform volumetric evaluation of the condyles in cases of radiographically evident condylar asymmetries to obtain a more accurate diagnosis.

A volumetric study of mandibular condyles in orthognathic patients by semiautomatic segmentation

Purpose

This study was conducted to elucidate volumetric data of mandibular condyles of orthognathic patients by analyzing cone beam computed tomography images based upon semiautomatic segmentation.

Methods

Cone beam computed tomography images of 87 patients with malocclusions were analyzed in this retrospective study. Patients were between 17 and 53 years old and diagnosed with Angle class I, II, or III malocclusion. By using the validated open-source software “ITK-SNAP,” the volumetric measurements of 174 mandibular condyles were performed. Volumetric analysis was performed according to intra-subject side differences by paired Student t test. In accordance to inter-subject side, gender, age and type of malocclusion differences bivariate analysis and ANOVA were applied.

Results

The mean volume for the right condyle was 1.378 ± 0.447 cm³, with a maximum of 2.379 cm³ and a minimum of 0.121 cm³. The mean volume for the left side was 1.435 ± 0.474 cm³, with a maximum of 3.264 cm³ and a minimum of 0.109 cm³. Bivariate analysis indicated a highly significant inter-subject difference between the volume of the left and right mandibular condyles (p < 0.01). Females had a significantly smaller condyle volume than males (p < 0.05 left condyle; p < 0.01 right condyle).

Conclusion

The fact that shape and volume of mandibular condyles show a high susceptibility to pathological alterations and particularly malocclusions makes a precise knowledge about volumetric changes indispensable. Our results show that significant inter-subject differences in condyle volume could be found with respect to the side and gender. Larger volumes could be assessed for the left condyle and for male patients.