The Visibility and Affecting Factors of Bifid Mandibular Condyles on Panoramic Radiography

Research Article

Austin J Dent. 2023; 10(2): 1175.

The Visibility and Affecting Factors of Bifid Mandibular Condyles on Panoramic Radiography

Ayse Zeynep Zengin¹*; Ahmet Eren Karabiyik²; Kübra Cam²; Hande S Dogruer²; Lale Rizeli²; Ayse Pinar Sumer³

1Associate Professor, Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Ondokuz Mayis University, Turkey

2Research Assistant, Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Ondokuz Mayis University, Turkey

3Professor, Research Assistant, Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Ondokuz Mayis University, Turkey

*Corresponding author: Ayse Zeynep Zengin Associate Professor, Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Ondokuz Mayis University, Turkey. Email: dtzeynep78@yahoo.com.tr

Received: September 15, 2023 Accepted: October 06, 2023 Published: October 13, 2023

Abstract

Aim: The aim of this study was to determine the visibility of Bifid Mandibular Condyle (BMC) and affecting factors on panoramic radiography compared with Cone Beam Computed Tomography (CBCT).

Material and Methods: Radiologically depression or notch on superior condylar surface or duplication of condylar head with continuous cortex on CBCT images was considered as BMC. Characteristics of BMC such as location, type, groove type, depth, and horizontal angle on CBCT images were noted. Panoramic radiographs of 63 BMC and 65 normal mandibular condyles confirmed on tomographic images were evaluated by three groups of observers with different experiences.According to the results, the common correct and incorrect estimations were compared.

Results: There was no statistically significant difference between the results of the observers.

Despite there was no statistically significant difference between the characteristics of BMC according to whether the estimations were correct or incorrect. (p>0,050), it was determined that the horizontal angle of the BMC that observers stated correctly was 20.5% less than the cases with bifid condyles that they stated incorrectly.

Conclusion: In conclusion, experience of clinicians had no effect on the visibility of BMC. Panoramic radiographs frequently misread bifidity and bifidity was only confirmed by the CBCT. However, it can be estimated that when the angle between the condylar head and the horizontal plane become closer, BMC is more likely to be detected on panoramic radiographs. Further studies are required to determine which factors have effect on visibility of BMC on panoramic images.

Keywords: Bifid mandibular condyle; Panoramic radiography; Cone beam computed tomography

Introduction

Bifid Mandibular Condyle (BMC) appeared as a double condylar head characterized by a vertical depression, notch or deep cleft in the center of the condylar head [1]. They are usually diagnosed by a panoramic radiography during a routine examination [2]. The panoramic radiography is useful for providing a broad overview of the Temporomandibular Joint (TMJ) and surrounding structures. Gross osseous changes in the condyles can be identified, such as asymmetries, extensive erosions, large osteophytes, tumors, or fractures. However panoramic radiographs can misread bifidity by the overlapping of anatomical structures or inherent distortion. They can either under or overestimate bifidity [3]. When a detailed assessment of bony structures of TMJ is needed, the panoramic view should be supplemented with advanced imaging techniques [1].

To avoid excessive radiation, clinicians can prefer Cone Beam Computed Tomography (CBCT) rather than other tomographic techniques. Cone Beam Computed Tomography (CBCT) can produce thin slices that allow the structures of the joints for determining the presence and extent of ankylosis and neoplasms, imaging fractures, and examining for heterotopic bone growth be assessed without superimposition of surrounding anatomy. The joints can be viewed in coronal and sagittal planes, corrected along the long axes of the condylar heads [1].

In 2005, Mawani et al. [4]. investigated condylar shape analysis using panoramic radiograph and conventional tomography. In 2006, Schmitter et al [5]. study about assessment of the reliability and validity of panoramic imaging for assessment of mandibular condyle morphology using both MRI and clinical examination as the gold standard. In 2007, Honey OB et al [6]. examined accuracy of CBCT imaging of the temporomandibular joint compared with panoramic radiolography and linear tomography. In 2020, Arayapisit et al [7]. studied on understanding mandibular condyle morphology on panoramic radiography compared with CBCT. In this study, we evaluated the efficiency of panoramic radiography in the visibility of BMC compared with CBCT imaging.

This study was aimed to evaluate the visibility of BMC on panoramic radiographs and to determine the factors affecting the visibility of BMC on panoramic radiograph compared with CBCT.

Material and Methods

The study was reviewed and approved by the Institutional Review Board of Ondokuz Mayis University (OMU KAEK 2022/231).

Tomographic Imaging

63 mandibular condyle showed bifidity on CBCT images were included in the present study. Radiologically depression or notch on superior condylar surface or duplication of condylar head with continuous cortex on CBCT images was considered as BMC [1]. CBCT evaluation was accepted as gold standard for BMC.

Presence of space occupying lesions within the temporomandibular joint area and low-quality CBCT images with motion blurring or imaging artifacts that could adversely affect the evaluation were excluded in the study. The CBCT evaluation was carried out in the axial, coronal, sagittal, cross-sectional, and tangential views using a standardized approach in viewing the CBCT scans (distance of 40 cm, dimly-lit room). The same CBCT scanner (Sirona Dental Systems, Bensheim, Germany), operating at 98kVp, 15-30 mA was used in all examinations. Voxel and FOV sizes were 0.25 mm3 and 15x15 cm. Exposure time of 2-6 seconds and scanning time was 14 seconds. Assessments were performed in 1 mm thickness slices by using “distance tool bar” feature of the SIDEXIS XG 2.56 (Sirona Dental Inc., Bensheim, Germany) image analysis program. All examinations were performed under light illumination at 3.7 MP, 68 cm, 2560 x 1440 resolution, 27-inch color LCD display (The RadiForce MX270W, Eizo Nanao Corporation, Ishikawa, Japan).

Image Analysis

Two dentomaxillofacial radiologists independently examined the CBCT for the presence of BMC. They came to a consensus in cases of disagreements.

The Examined Radiologic Properties of BMC were

¾Localization: right-left mandibular condyle.

¾Type of BMC:

• Mediolateral (ML) bifidity was assessed using coronal images parallel to the long axis of the condyle, mediolateral cases appears as “heart” shape in coronal images.

• Anteroposterior (AP) bifidity was assessed using lateral images perpendicular to the long axis of the condyle. Anteroposterior case appears as two condyles, one anterior to other, in sagittal reformat [8].

• Trifid/ Multiheaded: The formation of more than two condyles can be named Multi-Headed Condyles (MHC) [9].

¾The type of groove: The BMC divided into two parts by sulcus with variable depth. This splitting can range from shallow groove to deep groove [9].

• TyType 1 deep and narrow groove

• TyType 2 wide and shallow groove

¾The BMC depth: It was measured by the shortest distance from the line connecting the two highest points of the condyles to the lowest point of the condyles.

¾Horizontal angulation of each condyle were determined by measuring the angle between the long axis of the condyle in the axial cross-section with the largest ML dimension and an imaginary horizontal line [10].

After giving information about the radiographic appearance of BMC on panoramic views (that is divided into two parts of more or less equal size by a deep groove [11]), observers independently were asked to evaluate 128 mandibular condyles (63 BMC, 65 normal) on panoramic radiographs for presence or absence of BMC and signed in a special form. Three groups of observers consisting of four PhD students in dentomaxillofacial radiology [two of them were two-year asistants and two of them were one-year asistants] and two dentomaxillofacial radiology specialist [with at least 10 years’ experience] evaluated images separately. According to the answers of the observers from panoramic radiographs, the common correct and incorrect estimations were compared.

SPSS software version 23.0 (IBM Corp., Armank, NY, USA) was used to analyze the data. Suitability for normal distribution was evaluated by Kolmogorov-Smirnov. Kappa testt was used to compare categorical variables according to groups. The Mann-Whitney U test was used to compare the data that were not normally distributed according to the paired groups. The Kruskal Wallis test was used to compare the data that were not normally distributed according to groups of three or more, and multiple comparisons were analyzed with the Dunn test. Analysis results were presented as frequency (percentage) for categorical data, and as mean ± Standard Deviation, and median (minimum – maximum) for quantitative data. Significance level was taken as p<0.05.

Results

All BMC were in multiheaded and ML orientation. AP orientation could not found.

There was no statistically significant difference between the results of the experts, the results of the two-y-year asistants and the one-year asistants (p=0.261). Statistically good agreement was obtained between the three observer groups (K=0.640; p<0.001).

Considering the knowledge from the tomography and results of the observers, the rate of correct estimations was 51.4% (Figure 1a & 1b), while the rate of incorrect estimations (Figure 2a & 2b) was 48.6%. There was no statistically significant difference between localization, type of BMC, type of groove, BMC depth and horizontal angle of BMC values according to whether the estimations were correct or incorrect (p>0,050) (Table 1 & 2).