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Year : 2021  |  Volume : 13  |  Issue : 1  |  Page : 3-7

Comparison of Condylar Bone Density in Cone-Beam Computed Tomographic Images of Patients with and without Temporomandibular Joint Disorders

1 Department of Oral and Maxillofacial Radiology, School of Dentistry, Shiraz University of Medical Science, Shiraz, Iran
2 Department of Oral and Maxillofacial Radiology, Dental Implants Research Center, Dental Research Institute, School of Dentistry, Isfahan University of Medical Science, Isfahan, Iran

Date of Submission18-Apr-2021
Date of Acceptance07-Jun-2021
Date of Web Publication06-Aug-2021

Correspondence Address:
Dr. Parisa Soltani
School of Dentistry, Isfahan University of Medical Sciences, Hezar-Jarib Ave, Isfahan 8174673461
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jofs.jofs_89_21

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Introduction: Temporomandibular disorders (TMDs) are the main source of orofacial pain of nondental origin. Density changes in mandibular condyles of patients with TMD have not been well documented. The aim of this study was to compare condylar head bone density values in patient with and without TMD in cone-beam computed tomographic (CBCT) images. Materials and Methods: CBCT images of 70 patients with TMD and 70 age- and sex-controlled individuals were studied. Density of the cancellous bone in the left and right condylar heads was measured on a CBCT slice with the widest mediolateral dimension. Moreover, absence of at least one maxillary or mandibular posterior tooth (except for third molars) was recorded. Interclass correlation, t test, and Chi-squared test were used for statistical analysis. Results: Bone density in the condylar head significantly increased in patients with TMD compared with the non-TMD group (P < 0.001). The difference between males and females in each group was not significant (P = 0.182). Condylar head bone density in patients with TMD with posterior missing teeth was significantly less than individuals without missing teeth (P = 0.002). Conclusion: Increased density of condylar head must be regarded as a potential diagnostic tool for TMD when interpreting CBCT images of the joints.

Keywords: Bone density, cone-beam computed tomography, temporomandibular joint

How to cite this article:
Eisazadeh M, Khojastepour L, Haghnegahdar A, Soltani P. Comparison of Condylar Bone Density in Cone-Beam Computed Tomographic Images of Patients with and without Temporomandibular Joint Disorders. J Orofac Sci 2021;13:3-7

How to cite this URL:
Eisazadeh M, Khojastepour L, Haghnegahdar A, Soltani P. Comparison of Condylar Bone Density in Cone-Beam Computed Tomographic Images of Patients with and without Temporomandibular Joint Disorders. J Orofac Sci [serial online] 2021 [cited 2023 Jan 30];13:3-7. Available from:

  Introduction Top

Temporomandibular joint (TMJ) is a complex joint. The mandibular condyle is one of the most important components of the TMJ and is likely to be affected by the functional pressures caused by occlusion and jaw movements. This functional pressure is related to masticatory muscle function, age, and presence or absence of teeth.[1] Although condylar remodeling may occur for adaptation to the functional requirements, some structural changes are generally related to TMJ dysfunction, such as erosions, osteophytes, subchondral bone sclerosis, and pseudocysts.[2] Temporomandibular disorders (TMDs) are the main source of orofacial pain of nondental origin, which affect the soft tissue and bony components of the TMJ.[3] TMDs may also occur after operations such as orthognathic surgery or surgical extraction of third molars.[4],[5]

Studies have been performed on the changes in bone quality of the condylar component of patients with TMD. For instance, Arsan et al. evaluated the fractal dimensions of mandibular condyles in patients with TMD. They reported that decreased fractal dimensions showing decreased complexity of the trabecular pattern is associated with degenerative changes in the condyles.[6] In contrast, Çakur and Bayrakdar found no correlation between condylar bone quality and degenerative changes in patients with TMD.[7] Bone quality includes various macroscopic and microscopic components including the degree of mineralization.[8]

Recently, cone-beam computed tomography (CBCT) has gained application for evaluation of the osseous components of TMJ.[2],[9],[10],[11],[12],[13] Lower radiation dose and higher accessibility, as well as excellent visibility of details and three-dimensional reconstruction make CBCT an ideal choice for radiographic evaluation of the osseous components of TMJ. The aim of this study was to compare condylar head bone density values in patient with and without TMD in CBCT images.

  Materials and Methods Top

Ethical approval for this study (protocol No. 14357) was provided by the Ethical Committee of Shiraz University of Medical Sciences, Shiraz, on 6th February 2015. Seventy patients with clinical signs and symptoms of TMD lasting for at least 2 years were selected. The enrolled patients had at least one of the signs or symptoms: TMJ sounds such as click or crepitation, pain or tenderness in TMJ region, myofacial pain or tenderness, and nonharmonic mandibular movement such as limitation and deviation of mouth opening. The patients were referred to Department of Oral and Maxillofacial Radiology for obtaining CBCT images of the TMJs. CBCT images and clinical records of 70 sex- and age-matched patients, free from TMD symptoms, who sought treatment for purposes other than TMD were used as the control group. The nature and objective of the investigation were completely explained and a written consent was taken from all subjects enrolled in the study. Patients with a history of temporomandibular surgery or acute trauma, patients with congenital abnormalities, musculoskeletal or neurologic disorders, patients under the age of 18, and patients with systemic diseases were excluded from the study. In addition, patients with TMD with at least one missing premolar or molar teeth in one or both jaws (with no prosthetic replacement) were recorded. Third molars were not counted as missing teeth.

The CBCT examination was performed for all patients using a NewTom VGi scanner (NewTom, Verona, Italy), field of view size 15 × 12 cm, with the exposure parameters set at 120 kVp, 4.8 mA, and exposure time of 20 seconds in the standard resolution mode (voxel size 0.3 mm). The NewTom Cone-Beam 3D Imaging System workstation (NNT Software version 7, Verona, Italy) was used to prepare the TMJ images. The system automatically generated axial images, which were then scrolled to identify the axial view on which the condylar head revealed the widest mediolateral extent, then paracoronal cross sections, parallel to the long axis of the condyle reconstructed. The right and left TMJ areas of each patient were evaluated. In each side, the total area of condylar head (all parts of the condyle except cortical borders, from the superior articular surface down to the neck) was determined and then density of cancellous bone in this volume was measured [Figure 1]. Two dentomaxillofacial radiologists (with 4 years and more than 20 years of experience), whose regular practice involved interpretation of TMJ CBCT images, evaluated the images. The observers did not know if the image belonged to an individual in the TMD group or the non-TMD group. The observers independently assessed the images twice with a minimum interval of 14 days.
Figure 1 Determining region of interest for density measurements.

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Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS, version 18.0; SPSS Inc, Chicago, Illinois, USA). T test was used to compare condylar head bone density in TMD and non-TMD groups. The relationship between posterior missing teeth and condylar head bone density was assessed by t test. Chi-squared test was used to assess the relationship between TMD prevalence and posterior missing teeth. The interclass correlation (ICC) was used to ascertain inter- and intraexaminer reliability. A good interexaminer (ICC = 0.912, 95% confidence interval [CI]: 0.821–1) and intraexaminer (ICC: 0.924, 95% CI: 0.849–1) agreement was observed for all variables.

  Results Top

The TMD group consisted of 55 females and 15 males aged between 18 and 65 (mean = 32.66 ± 12.5). The control group consisted of 47 females and 23 males aged between 18 and 65 years (mean = 29.70 ± 10.21).

The results of the t test showed no statistically significant difference between mean age of patients with TMD (32.66 ± 12.50) and non-TMD (29.70 ± 10.21) (P = 0.128). Based on Chi-squared test, there was no statistically significant difference between the sexes in two groups (P = 0.128). Hence, the patients were matched for age and sex in both the groups.

According to our study, condylar head bone density significantly increased in patients with TMD compared with the non-TMD group (P < 0.001) [Table 1]. The difference between males and females in each group was not significant (P = 0.182) [Table 1]. Condylar head bone density in patients with TMD with posterior missing teeth was significantly less than individuals without missing teeth (P = 0.002) [Table 2].
Table 1 Mean (standard deviation) of condylar head density in individuals with and without temporomandibular disorders (TMDs) based on sex

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Table 2 Mean (standard deviation) of condylar head bone density in temporomandibular disorder patients with and without missing posterior teeth

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  Discussion Top

Based on the findings of this study, condylar head bone density was higher in patients with TMD compared to the non-TMD group. Condylar head bone density in patients with TMD with posterior missing teeth was significantly less than individuals without missing teeth.

Several methods have been applied for assessment of bone quality, including bone densitometry,[14] bone biopsies,[15],[16] quantitative computed tomography (CT),[17] and ultrasound.[18] Each method has its own limitations which may restrict its practical clinical use.[17] For instance, dual photon absorptiometry and dual energy X-ray absorptiometry can be used to measure bone density of the mandible but both of these methods evaluate an integrated sum of cortical and cancellous bone density.[8] Hounsfield units obtained by CT scanning are used as a standardized quantitative scale in bone densitometry with reliable and comparable results.[19],[20] These values can be easily extracted from CT scans of bone and soft tissues, by employing dedicated software incorporated in the CT imaging systems. Recent progresses in technology enable the CBCT software to calculate tissue density as well. However, the correlation between the gray values obtained using CBCT and Hounsfield unit on CT images is controversial. According to the study of Silva et al., bone density measured as gray values in CBCT images is unreliable, being higher than Hounsfield units obtained using CT.[21] However, Cassetta et al. suggested that applying a conversion rate based on linear correlation with CT values to CBCT values makes CBCT useful in determining bone density values.[22] In addition, Nomura et al. showed a correlation between CBCT voxel values and bone mineral density, but this relationship was not linear.[23] Moreover, the study of Lagravère et al. showed the capabilities of CBCT in evaluation of bone density.[17] Nackaerts et al. reported that gray values represented by CBCT are influenced by the device, imaging parameters, and imaging area position.[24] However, these parameters do not significantly change the results of our study, because of the comparative nature of our measurements.

Main indications for CBCT imaging of the TMJ include structural assessment of bony components of the joint, determination of the location and extent of bony alterations such as ankyloses, erosive degenerations, pseudo cysts, and osteophytes, presence of asymptomatic bone remodeling, hyperplasia of condyle, coronoid, and styloid processes, intra-articular calcifications, restriction of mandibular movement, failure to respond to conventional treatments, and presence of clinical findings that indicate a progressive pathological status in the joint.[25],[26] Thus, using the quantitative potentials of CBCT as an adjunct tool for identifying disorders in the joint components is valuable. Recognizing the pattern of bone density changes in TMD maybe potentially helpful in the diagnosis of this condition, as this method relies on objective quantitative calculations. Many studies have been carried out on CBCT findings of TMD. They found out that features such as osteophytes, Ely cysts, articular surface irregularities, and decreased joint space are more commonly observed in patients with TMD compared with the non-TMD group.[27],[28],[29],[30] However, bone density change in joints with TMD is less investigated. Consistent with our results, de Leeuw et al. showed that in terminal stage of TMD diseases, marked subchondral remodeling with unclear and sclerotic pattern occurs.[31] Shi et al. reported that in osteoarthritic TMJs, lower condylar bone density was observed. They concluded that condylar bone density along with bone volume fraction can be used as a potential diagnostic tool for TMJ osteoarthritis.[32] Felson and Nevitt noted that density changes in osteoarthritis diseases depend on both the site and stage of disease.[33] Our study was carried out on patients with TMD who did not necessarily have osteoarthritis. Arsan et al. used fractal analysis to investigate the complexity of trabecular pattern of the mandibular condyles in patients with TMD. They revealed that lower fractal dimensions were observed in joints with more severe degenerative changes. Therefore, they concluded that in TMD, the trabecular structure of condyles with erosive and sclerotic changes showed decreased complexity.[6]

In the present study, condylar head bone density in patients with TMD with missing of at least one posterior tooth was less than patients who were completely dentulous. The results of a study performed by Aggarwal et al. showed that condylar bone density decreases in patients with edentulous jaws. These findings might be result of reduced masticatory function due to tooth loss.[1]

According to studies, changes in bone density can be affected by age, sex, and hormonal changes.[34],[35] Therefore, to reduce the impact of these factors on the results, participants in the two groups were matched to these variables. Condylar bone density was higher in males compared with females. A micro-CT study by Coogan et al. revealed that the trabecular bone of mandibular condyles have microstructural differences between the sexes.[36] The differences in trabecular microstructure may explain the different bone densities in males and females.

Although based on our findings, a significant increase in the density of condylar bone was observed in patients with TMD, further recognition of the nature of these changes is needed. The type, duration, and severity of the disease must be considered for interpretation of bone density changes in patients with TMD. The required radiographic data can be achieved easily from CBCT scans, highlighting the role of CBCT imaging in TMD diagnosis and treatment.

As the sample size of the present study is not large enough, the comparison between different type of TMDs and different groups of patients (with regard to their sex, age, and pre- or postmenopausal women) would not be reliable. Studies with larger sample size are recommended to gain more detailed and reliable results. In addition, the exact relationship between radiographic appearance of bone and true mineral content should be investigated.

  Conclusion Top

Condylar head bone density in patients with TMD with posterior missing teeth was significantly less than individuals without missing teeth. The density of condylar head must be regarded as a potential diagnostic tool for TMD when interpreting CBCT images of the joints.

Financial support and sponsorship

This study was financially supported by Shiraz University of Medical Sciences.

Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1]

  [Table 1], [Table 2]


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