Journal of Indian Academy of Oral Medicine and Radiology

: 2021  |  Volume : 33  |  Issue : 4  |  Page : 364--371

Assessment of correlation between bone quality and degenerative bone changes in temporomandibular joint by computed tomography -A retrospective study

Neha Koshal1, Deepa Jatti Patil2, Sanjeev Laller3, Mamta Malik3, Ramandeep Singh Punia4, Hemant Sawhney5,  
1 Consultant Dental Radiologist, Department of Radiology, Atulya Diagnostic Centre, Chandigarh, Punjab, India
2 Department of Oral Medicine and Radiology, K. M. Shah Dental College and Hospital, Vadodara, Gujarat, India
3 Department of Oral Medicine and Radiology, Faculty of Dental Sciences, PDM University, Bahadurgarh, Haryana, India
4 Department of Oral Medicine and Radiology, Dasmesh Institute of Research and Dental Sciences, Faridkot, Punjab, India
5 Department of Oral Medicine and Radiology, School of Dental Sciences, Sharda University, Greater Noida, Uttar Pradesh, India

Correspondence Address:
Dr. Deepa Jatti Patil
Department of Oral Medicine and Radiology, K. M. Shah Dental College and Hospital, Sumandeep Vidyapeeth Deemed to be University, Piparia, Gujarat


Objectives: This study was performed to assess the correlation between bone quality and degenerative bone changes in temporomandibular joints on computed tomographic images. Methods: Temporomandibular joints of 100 patients who underwent computed tomography were analyzed retrospectively. Sagittal and coronal images of the joint (condyle and articular eminence) were assessed for bone quality type 1 to 4 and degenerative bone changes. A Chi-square test was used to assess the descriptive statistics. One-way ANOVA was used to compare the degenerative changes in different age groups and gender. The post hoc Tukey honesty significance test was used to assess the presence of a statistically significant difference between the degenerative changes and bone quality. A value P < 0.005 was considered statistically significant. Results: The retrospective analysis included 48 women and 52 men with ages ranging from 17 to 85 years (mean age 52 years). D3 quality of bone was most commonly observed in the condyle and articular eminence. Osteophytes were the most common degenerative changes observed in the condyle and no significant degenerative changes were seen in the articular eminence. There was a correlation between degenerative changes and bone quality of condyle with respect to age. There was no correlation between the bone quality of the condylar head and its degenerative changes. Conclusion: There was no correlation between the type of bone quality and degenerative bony changes of the condyle and articular eminence, but most of the patients with degenerative changes had a poor-quality bone.

How to cite this article:
Koshal N, Patil DJ, Laller S, Malik M, Punia RS, Sawhney H. Assessment of correlation between bone quality and degenerative bone changes in temporomandibular joint by computed tomography -A retrospective study.J Indian Acad Oral Med Radiol 2021;33:364-371

How to cite this URL:
Koshal N, Patil DJ, Laller S, Malik M, Punia RS, Sawhney H. Assessment of correlation between bone quality and degenerative bone changes in temporomandibular joint by computed tomography -A retrospective study. J Indian Acad Oral Med Radiol [serial online] 2021 [cited 2022 May 17 ];33:364-371
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Temporomandibular disorders (TMD) are complex multifactorial disorders affecting the temporomandibular joint (TMJ). TMJ is a diarthrodial joint permitting rotational and translational movements of the mandible.[1] The TMDs broadly include masticatory muscle disorders, internal derangement of the articular disc and degenerative disorders of the joint. The etiology of TMDs is multifactorial and includes various factors such as trauma, emotional stress, muscular hyperactivity, inflammatory and degenerative diseases.[2]

Analogous to other diarthrodial joints of the body TMJ is prone to osteoarthritis. Osteoarthritis is a degenerative disorder due to increased loading of the joint causing operational changes in the structures of TMJ.[3] The clinical manifestations include joint pain, decreased range of motion, joint sounds like crepitus and clicking and in severe cases can manifest as facial asymmetry and open bite.[2] The degenerative changes on radiographs manifest as flattening, erosion, osteophytes, sclerosis, and pseudocysts. Assessment of the stage of degenerative change aids in diagnosis and management. Conservative management includes medications such as nonsteroidal anti-inflammatory drugs, physiotherapy, arthrocentesis and in severe cases may require TMJ prosthesis.[4]

According to Radin and Rose, the health and integrity of the TMJ articular cartilage is influenced by bone quality and any alterations in bony architecture of condyle can lead to degenerative changes of the TMJ.[5] Bone quality of jaws has been a subject of interest amongst several researchers especially during pre-operative implant planning. The bone quality comprises of various several features like microarchitecture, matrix and mineral content.[6] The classification proposed by Lekholm and Zarb to assess bone quality based on the quantity of cortical bone versus trabecular is widely used to evaluate patient bone for dental implant placement. It is divided on a scale of I -IV with types I and IV bone having the best and worst quality, respectively. The bone quality index (BQI) is a four-point index (I–IV) that describes four types of bone quality: I, composite of homogeneous and compact bone; II, thick layer of compact bone surrounding a core of dense trabecular bone; III, thin layer of cortical bone surrounding a dense trabecular bone. of favorable strength; and IV, thin layer of cortical bone surrounding a core of low-quality trabecular bone.[7]

Researchers have discovered distinct architectural changes in the subchondral bone of osteoarthritis-affected joints (particularly the knee, hip, and vertebrae). This could be a precursor to the fact that changes in the TMJ's subchondral bone can be an early indicator of degeneration. As a result, examining the TMJ's internal trabecular architecture can aid in early diagnosis before cortical bone resurfaces in the latter stages of the disease.[8],[9] There are very few research that look at the relationship between condylar bone quality and TMJ degeneration in depth. In similar vein, Cakur et al.[10] conducted research to see if there was a link between bone quality and degenerative changes in the condyle and articular eminence on CBCT images. They discovered a high incidence of Type III bone in the condyle and articular eminence, implying that people with TMDs have poor bone quality. CBCT imaging for assessing trabecular structures and bone integrity, on the other hand, is still not commonly accepted. Therefore, the goal of this study was to determine association between the bone quality of the mandibular condyle and articular eminence on computed tomographic (CT) images and degenerative bone alterations.

 Materials and Methods

The present retrospective study was carried out in an Advanced Imaging center. The sample size was calculated by the formula [INSIDE:1] The input values were based on the study carried out by Cakur et al.[10] By taking reference of that with 95% Cl and 70% power the sample size was calculated as 100. The procedures used are in compliance with the Helsinki Declaration of 2000 and ethical norms for human experimentation. The present radiographic analysis is a retrospective study carried out in a state-of-the-art digital imaging facility. For this reason, clearance from the institutional ethical board was not obtained. Prior to the Imaging procedure, the patients gave their informed consent. From the digital imaging and communications in medicine (DICOM) archival folder, the CT image volumes of 100 patients were retrieved. CT images were obtained using a Siemens Somatom definition- dual source 64 slice CT (4128 slices) with a 9-inch field of view and 750-micron resolution. The kvp and mA values were set to 120 and 90, respectively. The analysis was performed in all the three planes and sections, coronal, axial, and sagittal views in bone window with a width of 2000 and a level of 400. The slice has a thickness of 0.75 with a 0.5 interval. Osirix - Mac pro database was the software utilized. The patients in the study ranged in age from 18 to 60 years old. The CT pictures were recommended for a variety of dento -maxillofacial reasons, including maxillofacial diseases, dental implants, and orthodontic treatment, among others. The study excluded patients having a history of trauma or surgery in the oral and maxillofacial region.

The bone quality and degenerative bone alterations of the TMJ were assessed using CT imaging. The assessment was performed by two experienced oral radiologists in a gap of two months.

The radiological alterations observed in the mandibular condyle and articular eminence were evaluated as described by Anjos Pontual[11] (2012) as follows:

Flattening: Is a loss of even convexity or concavity of the joint outline and flat bony contour deviating from the convex or concave formSclerosis: Is an area of increased quality and thickness of the cortical bone on the joint surfaceErosion: Is a local area of rarefaction and decreased quality in the cortical plate of the joint surfaceOsteophytes-Appear as marginal bony outgrowths of the bone arising from a mineralized joint surfacePseudocyst: Is a well-circumscribed radiolucent area without cortical destruction that could be immediately below the cortical plate or deep in the trabecular boneBone quality (BQ): The bone quality was evaluated according to the quantity and magnitudes of cortical bone and trabecular bone in 4 types as described by Lekholm.[7]

D1- homogeneous cortical boneD2- thick cortical bone with marrow cavityD3- thin cortical bone with dense trabecular bone of good strengthD4- very thin cortical bone with low-quality trabecular bone of poor strength.

Statistical analysis

On a data sheet, the findings were tabulated, and the results were analyzed using Statistical package for the social sciences (SPSS 18). The Chi-square test and Pearson's coefficient were employed to assess the relationship between BQ and degenerative bone changes in descriptive statistical analysis. The mean values of bone quality between female and male patients were compared using t test. To compare the degenerative changes in different age groups and genders, one-way ANOVA was utilized. The presence of a statistically significant difference between degenerative alterations and age was determined using the post hoc Tukey honesty significance test (HSD). The Kruskal–Wallis test was used to determine the relationship between condyle bone quality and articular prominence with degenerative changes of condyle. A value of P < 0.005 was considered statistically significant.


The retrospective analysis included 48 women and 52 men with age ranging from 17 to 85 years (mean age 52 years) SD ± 16.43 [Figure 1] Degenerative changes were seen more on the left side (53%) (28 men and 25 women) as compared to the right side (47%) (24 men and 23 women). In the women the left side was more affected than the right side. There was no statistically significant correlation seen (P = 0.860) [Figure 2] and [Figure 3] depicts the bone quality and degenerative changes of condyle according to gender (P = 0.095){Figure 1}{Figure 2}{Figure 3}

Degenerative radiographic bone alterations [Figure 4] and [Figure 5]{Figure 4}{Figure 5}

Condylar head: The following changes were observed; Flattening (14), erosion (20), Sclerosis (21), Osteophyte (38%) and Pseudocyst (7) were seen.Articular eminence: No degenerative change was observed in 97, erosion (2) and sclerosis (1)

Bone Quality observed radiographically [Figure 6] and [Figure 7]{Figure 6}{Figure 7}

Condylar head: D1 (1), D2 (26), D3 (64), D4 (9)Articular Eminence: D2 (15), D3 (65), D4 (20)

More degenerative changes were seen in the condyle as compared to the articular eminence. [Figure 4] P <.0.005. There was a correlation between degenerative changes and bone quality of condyle with respect to age [Figure 8]. There was no significant gender differences in bone changes [Table 1] [Table 2] depicts the degenerative changes of condyle according to age. One-way ANOVA reveals no significant difference in degenerative changes according to age [Table 3]. The post hoc Tukey HSD test result for degenerative changes of condyle also showed no statistically significant difference according to age [Table 4]. D3 was the most common quality of bone seen in the condyle and most of the degenerative changes were seen in D3 type of bone but the result was not statistically significant (P = 0.312) [Table 5]. The Kruskal Wallis test results showed no correlation between bone quality of condyle &articular eminence with degenerative changes of condyle (P = 0.032) [Table 6]. The interobserver kappa ratio was 0.76 and showed good agreement between the two observers.{Figure 8}{Table 1}{Table 2}{Table 4}{Table 5}{Table 6}


In TMJ imaging, CT is preferable to CBCT because it reveals the bony components of the joint and bone quality in more detail.[12] However, because of the lower radiation dose and lower cost, CBCT is widely used for TMJ imaging. CT scans show the bone quality pattern distinguishing the trabeculae and marrow gaps better than CBCT images. CT scans are a crucial aspect of TMJ diagnosis. Thin incisions of up to 0.5 mm can be made from the thick articular structures. The overlapping of pictures of superficial and deep TMJ structures is reduced as a result. The test calculates the distance between the TMJ's bony components in proportions to the actual 1:1 while completing a comprehensive tracing of the area. Because of the high-resolution imaging, discrepancies between tissues of different densities can be seen, such as in the early phases of an inflammatory and/or infectious condition on the articular surface. As a result, CT images allow for a more thorough examination of the joint region, resulting in a more accurate diagnosis.[12] As a result, the relationship between bone quality and degenerative alterations in the condyle and articular eminence on CT images was investigated in this study.

Degenerative bone changes are non-inflammatory synovial joint degenerative diseases. The knee, hips, spine, and fingers are the most commonly affected stress-bearing joints in the body.[13] Other joints in the body, such as the wrist, shoulder, ankle, and TMJ, can be affected by osteoarthritis. TMJ osteoarthritis affects the cartilage, subchondral bone, synovial membrane, and other hard and soft structures, resulting in TMJ remodeling, abrasion, and degradation.[14],[15]

A high prevalence of degenerative changes was observed on the CT images in the present study. Degenerative changes were seen in 50% of the joints (including both the right and left side). In our study 48% were women and 52% were men and the observed degenerative changes were almost equal in both the sexes with a slight predilection for men. No gender predilection has been observed in some studies.[10],[16] This is in contrast with other studies which observed a greater occurrence in women.[17],[18] This can be explained by estrogen and prolactin hormone impacts, which may accelerate articular cartilage and articular bone degradation as well as activate a series of immunological responses in the TMJ matrix.[12]

In the present study, the prevalence of degenerative disorders increased with age and is in corroboration with other studies.[17],[18],[19] The degenerative changes are commonly seen in adults and elderly population. In our study, the mean age of the study population was 52 years and a correlation was seen between age, bone quality and degenerative changes. Osteoarthritis can occur at any age, although, it occurs with greater frequency as age increases. At 40 years of age, only 20% of the population may have osteoarthritis; however, by 65 years the rates drastically increase and a majority will exhibit radiographic evidence of the disease. Many studies have shown presence of radiographic evidence of degenerative changes in the fifth to sixth decade of life and reduction after the age of 75 years.[4],[19],[20],[21] In our study the prevalence pattern exhibited a bell-shaped curve (18-65 years and mean age was 52 years) with peak prevalence in 5th and 6th decade of life.

Various studies in the literature have observed degenerative changes of the TMJ occurring in the condyle and the articular eminence. In our study, the degenerative changes were seen more on the condyle than the articular eminence and similar results were observed by Campos et al.,[22] Pontual et al.[11] and Cakur et al.[10] The degenerative changes are seen more commonly on the weight-bearing joints, enveloped by hyaline cartilage. The TMJ differs from other joints in that the bone of the mandibular condyle is located just beneath the fibrocartilage, making it particularly vulnerable to inflammatory damage.[23] In addition, due to mechanical loading during growth, the mandibular condylar cartilage undergoes endochondral ossification and vigorously remodels.[24] Osteoarthritis is commonly seen in the condyle, but very few studies have been performed to evaluate its bone density.[25]

The most common degenerative change seen in the condyle in our study was osteophytes, sclerosis, erosion, flattening and pseudocyst in decreasing order of frequency. In the articular eminence degenerative changes were observed in 3 joints (erosion in 2 and sclerosis in 1 joint) Similar results were seen by Olveria et al.[20] who observed osteophytosis as the most prevalent change, followed by sclerosis and erosion. Pontual et al.[11] observed flattening and osteophytosis as the most predominant degenerative bone changes. In a study by Cakur et al.[10] erosion was the predominant finding in the mandibular condyle, and sclerosis was the predominant finding in the articular eminence.

Presence of erosion is a radiographic sign of the ongoing destructive process, whereas osteophyte is suggestive of the adaption of condyle to previous degenerative changes.[24] Osteophyte also known as bony spur is one of the hallmark radiographic features of degenerative joint disease. Development of osteophyte is seen previous to joint space narrowing and is associated with misalignment of joint to the side of the osteophyte, which is a main risk factor for the development of arthritic conditions. Instability of the joint is found to be a biomechanical trigger for the formation of osteophyte.[25] Nagaosa et al.[26] stated that osteophyte may differ in shapes, and its curvature or placement may stabilize the joint. The cartilage of the articular surface of the condyle and glenoid fossa/eminence can undergo bony remodeling when mechanical stresses exceed the adaptive capacity of the host to repair the joint and withstand loading forces by increasing the surface area.

Another important factor to understand is whether the degenerative changes are correlated with bone quality. According to some authors poor quality of bone or degenerative changes in the condyle can be an indicator of osteoporosis and TMJ osteoarthritis. In the present study 63 patients had D3 type of bone in the condyle and osteophytes and sclerosis were the common degenerative changes seen. Majority of the degenerative changes were seen in D3 type of bone but the result was not statistically significant (p value 0.312) There was no correlation between presence of decreased bone quality and degenerative change. But majority of the patients with degenerative changes had poor quality of bone. Our results are similar to the study performed by Cakur et al.[10] who observed poor quality of bone in patients with TMDs. Shi et al.,[27] performed a study to explore the association of bone quality and TMJ osteoarthritis. Their results predicted low condylar bone quality which was significantly correlated with development of TMJ osteoarthritis. They predicted that bone quality can be used as a potential diagnostic tool for early detection of TMJ osteoarthritis.

Few studies have been performed to assess if there is any correlation between osteoporosis and osteoarthritis. According to a study by Yamada et al.[28] the bone density of mandible was highly correlated with lumbar bone density, thus predicting that patients with systemic osteoporosis may have a high rate of low condylar BMD and vice versa. Bäck K et al.[29] conducted a study to elucidate the relation between osteoporosis and osteoarthritis/arthrosis (OA) in the temporomandibular joint (TMJ). They concluded that the prevalence of osteopenia/osteoporosis was not predictive of radiological or clinical findings of OA in the TMJ. Panoramic radiograph was used to study the bony alterations and quality and it has low sensitivity in detecting the bony changes. The results therefore cannot be generalized to the entire population. They suggested to perform prospective studies in patients with TMJ osteoarthritis with osteoporosis to establish a relationship between osteoporosis and TMJ osteoarthritis. In osteoporosis the radiographic changes in the TMJ include resorption of its constitute attachments like the condylar outline and the articular eminence. The other main oral manifestations of osteoporosis are related to the reduction of the alveolar ridge, increased porosity of the mandible and maxilla bone, periodontal changes, greater spacing between the bone trabeculae and the decrease in the maxillary bone mass and density.[30] The degenerative changes of the condyle are multifactorial and cannot be accredited to one particular cause. The other influencing factors like presence of systemic co-morbidities, advancing age, hormonal imbalance with alterations in mechanical loading (parafunction, trauma) can predispose to develop osteoarthritis and should be included in preventing bias due to confounding factors.[10]

Although recently CBCT has been used to assess the bone quality due to decreased radiation dose and cost, CT is superior to CBCT in assessing the bone quality. According to some studies prescribing CBCT to assess bone quality is still not widely accepted clinically, and its use is still debated. Hua et al.[31] conducted an in vitro study to assess the bone quality on CBCT images. They suggested CBCT images had potential for fractal analysis and bone area measurement to evaluate bone quality, although quality measurements are not valid.

 Limitations and Future Prospectives

The major limitation of our study is decreased sample size and due its retrospective nature the clinical findings could not be correlated. Future prospective studies should be planned correlating the clinical findings, age, gender, bone quality and degenerative change in a larger population.


There was a correlation between advancing age, bone quality and degenerative changes. Although most of the degenerative changes were observed in D3 type of bone in the condyle no statistically significant result was observed. It is notable to point out here that most of the degenerative changes were associated with poor quality of bone. Therefore, while examining the TMJ, it is imperative to examine its bone quality. This could facilitate early detection of TMJ arthritis and patients can be educated to avoid the predisposing factors consequently.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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