Temporomandibular joint osteoarthritis: cone beam computed tomography findings, clinical features, and correlations

Abstract

The aim of this study was to determine the prevalence of and associations between clinical signs and symptoms and cone beam computed tomography (CBCT) findings of temporomandibular joint osteoarthritis (TMJ-OA). Seventy-six patients (total 117 TMJ) with osteoarthritis were included in this study. Clinical signs and symptoms and CBCT findings were reviewed retrospectively. A considerable decrease in mandibular motions and mastication efficiency, and considerable increase in joint sounds and general pain complaints were observed. The most frequent condylar bony changes were erosion (110 joints, 94.0%), followed by flattening (108 joints, 92.3%), osteophytes (93 joints, 79.5%), hypoplasia (22 joints, 18.8%), sclerosis (14 joints, 12.0%), and subchondral cyst (four joints, 3.4%). Flattening of the articular eminence and pneumatization were each observed in five joints. Forty-one patients had bilateral degeneration and 35 had unilateral degeneration. Hypermobility was detected in 47 degenerative joints. Masticatory efficiency was negatively correlated with both condylar flattening and sclerosis, and general pain complaints was positively correlated with condylar flattening. Condylar erosion, flattening, osteophytes, pain, joint sounds, reduced jaw movements, and worsened mastication were common findings in TMJ-OA in the present study. Poor correlations were found between osseous changes and clinical signs and symptoms of TMJ-OA. CBCT is a powerful diagnostic tool for the diagnosis of TMJ-OA.

Osteoarthritis is a chronic, progressive, and debilitating disease, and is defined as the gradual deterioration (degeneration) of the cartilage in a joint. Temporomandibular joint osteoarthritis (TMJ-OA) is more frequent in females and its prevalence increases in relation to age. Many factors such as overloading, bruxism, unilateral chewing, genetic factors, and internal derangement are held responsible for the development of TMJ-OA.

Cone beam computed tomography (CBCT) systems offer many advantages over medical CT for diagnosis and treatment planning in dentistry, including a lower radiation dose for the patient, an affordable alternative to medical CT in terms of cost, a shorter acquisition time for the resolution required in dentistry, better resolution, the ability to acquire three-dimensional (3D) images, and the greater level of detail provided. The morphology of the osseous joint components, cortical bone integrity, and subcortical bone destruction/production can be viewed with higher sensitivity with the use of CBCT. However, there are disadvantages associated with CBCT scanners, including increased scatter radiation, beam hardening artefacts, and the inability to display Hounsfield units, which can provide a better quantitative assessment of bone density at the time of diagnosis.

With the gradual progressive destruction of articular tissues and concomitant advanced degeneration, the subchondral cortical layer is lost and erosion and other radiographic signs of osteoarthritis appear. Often, TMJ-OA is at an advanced stage at the time when it is perceived clinically and/or radiographically. The prevalence of clinical signs and symptoms of TMJ-OA have not been evaluated extensively in previous studies and these studies are limited in number. Equivocal results have been reported in previous studies attempting to correlate the intensity of clinical signs and symptoms with the quality of bony changes in TMJ-OA using different imaging modalities.

The aim of this study was to determine the prevalence of and associations between clinical signs and symptoms and CBCT findings of TMJ-OA.

Methods

The study population comprised patients presenting for the evaluation and management of TMJ-OA between January 2012 and June 2014 at the department of oral and maxillofacial surgery of the study institution in Turkey. This study was approved by the ethics board of the university. Patients were informed about the study and written consent was obtained from each subject.

To be included in the study sample, the patient had to meet the following criteria: (1) willingness to participate in the study; (2) TMJ-OA according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD axis I group IIIb); and (3) adequate existing clinical and CBCT data.

The diagnosis of osteoarthritis was made according to the DC/TMD (DC/TMD axis I group IIIb) published by Schiffman et al., as follows : (1) patient history positive for one of the following: any TMJ noise presented with jaw movement or function in the last 30 days, or patient report of any noise presented during the examination. (2) During the clinical examination, crepitus detected with palpation during at least one of the following: opening, closing, and right or left lateral, or protrusive movement(s). (3) TMJ CBCT positive for at least one of the following: subchondral cyst(s), erosion(s), generalized sclerosis, or osteophytes. Flattening or cortical sclerosis may be a precursor to frank degenerative joint disease, but they may represent normal variation, ageing, and remodelling. Flattening or cortical sclerosis is considered when other the TMJ CT criteria are present ( Fig. 1 ).

Fig. 1
CBCT images of a case with bilateral TMJ osteoarthritis (coronal and sagittal views).

Patients were excluded if they had a previous history of TMJ treatment or surgery, a previous history of trauma to the jaws, TMJ pain associated with another joint disorder, a systemic, rheumatic, neurological/neuropathic, endocrine, or immune/autoimmune disease with widespread pain, a previous history of radiation treatment to the head and neck, were pregnant, or if there was inadequate existing clinical and CBCT data.

The main outcome variables included maximum inter-incisal opening (MIO) measurements (both painless opening and maximum mouth opening), visual analogue scale (VAS) evaluations of masticatory efficiency, pain complaints, and joint sounds, and CBCT findings, and correlations between them. All clinical data were assessed by the same oral and maxillofacial surgeon (SCK) and recorded for statistical evaluations.

MIO measurements were made from the incisal border of the central upper incisor to the same point on the lower incisor. MIO with and without pain and lateral–protrusive motions of the mandible were measured with a millimetre rule.

A VAS was used to assess pain complaints, masticatory efficiency, and self-perceived joint noise. The VAS is a continuous scale comprising a horizontal line 10 cm (100 mm) in length, ranging from a score of 0 to a score of 10 (at 100 mm), anchored by two descriptors at the two ends: one for ‘no’ symptoms and the other for ‘extreme’ symptoms. The patient marked the position on the line that best represented their situation. The marked line was then measured with a ruler and the parameter assigned a score. For pain intensity, the scale was anchored by ‘no pain’ (score of 0) and ‘pain as bad as it could be’ (score of 10). For masticatory efficiency, the scale was anchored by ‘bad’ or ‘chewing liquid foods’ (score of 0) and ‘excellent’ or ‘chewing hard foods’ (score of 10). For self-perceived pathological noise intensity during joint movement, the scale was anchored by ‘no noise’ (score of 0) and ‘noise as excessive as it could be’ or ‘the worst imaginable’ (score of 10).

A second pain scale including five grading levels was used to assess pain intensity during different functions (rest, mastication, phonation, and yawning) and during bilateral digital palpation of the lateral and posterior TMJ. For this scale, pain intensity was graded as 0 = absent, 1 = slight, 2 = moderate, 3 = intense, or 4 = severe. The patient marked the pain intensity. The marked value was used as the pain intensity score for the different functions and palpation of the TMJ.

CBCT images of the bilateral TMJ were obtained using a NewTom 3G flat panel based CBCT machine (QR s.r.l., Verona, Italy). All images were recorded at 110 kV and 3–5 mA, 0.16-mm voxel size, and had a typical exposure time of 5.4 s. Images were viewed in the axial (0.5-mm diameter), coronal (2-mm diameter), and sagittal (2-mm diameter) planes. The images were obtained during maximum intercuspation and maximum opening. All radiological assessments were performed by the same oral and maxillofacial radiologist who has 12 years of experience in the diagnosis of TMJ-OA on CBCT images.

The observer was asked to evaluate the following imaging characteristics relating to osseous changes of the condyles: (1) flattening, defined as a flat bony contour deviating from the convex form; (2) erosion, defined as an area of decreased density of the cortical bone and the adjacent subcortical bone; (3) osteophytes, defined as marginal bony outgrowths on the condyle; (4) sclerosis, defined as an area of increased density of cortical bone extending into the bone marrow; (5) subchondral cyst; (6) condylar hypoplasia or hyperplasia; and (7) bifid condyle.

Osseous changes of the condyle were evaluated as follows: flattening, subchondral cyst, condylar hypoplasia or hyperplasia, bifid condyle (0 = absent, 1 = present); erosion, osteophytes, or sclerosis (0 = absent, 1 = slight, 2 = moderate, 3 = severe); condylar motion (1 = normal, 2 = hypomobility, 3 = hypermobility).

The severity of erosion in the condylar head was defined as follows: grade 0 in the absence of erosion; grade 1 in the presence of slight erosion, when decreased density was observed only in the cortical bone; grade 2 in the presence of moderate erosion, when decreased density was observed in the cortical bone and extended to the upper layers of the adjacent subcortical bone, with the erosions appearing as pitted and irregular contours of the bone surfaces; grade 3 in the presence of extensive erosion, when decreased density was observed in the cortical bone and extended below the upper layers of the adjacent subcortical bone, with the erosions appearing as very irregular contours of the bone surfaces.

The severity of osteophyte formation in the condylar head was defined as follows: grade 0 in the absence of osteophyte formation; grade 1 in the presence of slight osteophyte formation, when marginal bony outgrowth on the condyle was less than 1 mm; grade 2 in the presence of moderate osteophyte formation, when marginal bony outgrowth on the condyle was 1–2 mm; grade 3 in the presence of extensive osteophyte formation, when marginal bony outgrowth on the condyle was more than 2 mm.

The severity of sclerosis in the condylar head was defined as follows: grade 0, indicating absence; grade 1, indicating slight sclerosis, with a minimal increase in the thickness of the condylar cortical bone; grade 2, indicating moderate sclerosis, with a moderate increase in the thickness of the condylar cortical bone; grade 3, indicating extensive sclerosis, with a profound increase in the thickness of the condylar cortical bone.

Osseous changes of the articular fossa were evaluated as follows: erosion, sclerosis, and resorption (0 = absent, 1 = present); flatting of the articular eminence (0 = absent, 1 = present).

The degenerative TMJ side was numbered as follows: 1 for the right side, 2 for the left, and 3 for bilateral.

The evaluations were performed on lateral slices at the subjective closest distance between the condyle and mandibular fossa using the NewTom CBCT software.

Statistical analyses

All statistical analyses were performed using SPSS for Windows software, version 17.0 (SPSS Inc., Chicago, IL, USA). A P -value of less than 0.05 was considered statistically significant. Descriptive statistical data were recorded, and the data were assessed with the Kolmogorov–Smirnov test to identify the distribution. A correlation analysis was performed between clinical signs and symptoms and CBCT findings related to the condyle (erosion, osteophytes, flattening, and sclerosis) and age. The correlations were assessed with Spearman’s rho correlation test.

Results

Seventy-six patients with TMJ-OA (total 117 TMJ) were included in this study. Sixty-five were female (85.5%) and 11 were male (14.5%), and they ranged in age from 14 to 73 years (mean age 30.75 ± 12.68 years).

Prevalence of clinical signs and symptoms

With regard to mandibular motion, measurements of MIO with pain (maximum mouth opening), MIO without pain (painless mouth opening), lateral motion, and protrusive motion were 40.90 ± 8.13 mm, 29.66 ± 9.81 mm, 7.50 ± 2.86 mm, and 7.76 ± 2.69 mm, respectively. Using the VAS, the following scores were recorded for joint sounds, mastication efficiency, and general pain complaints: 5.62 ± 3.37, 6.43 ± 2.77, and 5.94 ± 2.39, respectively ( Table 1 ).

Table 1
Clinical parameters of the TMJ-OA patients (mean ± standard deviation).
Painless mouth opening (mm) 29.66 ± 9.81
Maximum mouth opening (mm) 40.90 ± 8.13
Lateral motion (mm) 7.50 ± 2.86
Protrusive motion (mm) 7.76 ± 2.69
Joint sound (VAS score) 5.62 ± 3.37
Mastication efficiency (VAS score) 6.43 ± 2.77
General pain complaints (VAS score) 5.94 ± 2.39
TMJ-OA, temporomandibular joint osteoarthritis; VAS, visual analogue scale.

Of the 76 patients, 37 (48.7%) experienced pain during rest, 64 (84.2%) during mastication, 47 (61.8%) during phonation, and 62 (81.6%) during yawning. Pain during lateral palpation of the TMJ was found for 62 (53.0%) joints, whereas pain on posterior palpation was found for 27 (23.1%) joints ( Table 2 ).

Table 2
Pain during function and palpation of the TMJ.
Absent Present Slight Moderate Intense Severe
n % n % n % n % n % n %
Pain during rest a 39 51.3 37 48.7 16 21.1 16 21.1 2 2.6 3 3.9
Pain during mastication a 12 15.8 64 84.2 8 10.5 22 28.9 11 14.5 23 30.3
Pain during phonation a 29 38.2 47 61.8 22 28.9 14 18.4 1 1.3 10 13.2
Pain during yawning a 14 18.4 62 81.6 7 9.2 16 21.1 14 18.4 25 32.9
Pain during lateral palpation of the TMJ b 55 47.0 62 53.0 26 22.2 15 12.8 4 3.4 17 14.5
Pain during posterior palpation of the TMJ b 90 76.9 27 23.1 10 8.5 10 8.5 2 1.7 5 4.3
TMJ, temporomandibular joint.

a n = number of patients.

b n = number of joints.

Radiological findings

Of the 117 joints with osteoarthritis, 108 (92.3%) showed condylar flattening, 110 (94.0%) showed condylar erosion, 93 (79.5%) showed condylar osteophytes, 14 (12.0%) showed condylar sclerosis, 22 (18.8%) showed condylar hypoplasia, and four (3.4%) showed a subchondral cyst. One joint showed sclerosis of the articular fossa and one showed a bifid condyle. Flattening of the articular eminence and pneumatization were each observed in five joints (4.3%). No condylar hyperplasia, erosion, or resorption of the articular fossa was observed in any joint ( Table 3 ).

Table 3
CBCT results showing osseous changes related to the condyle, articular fossa, and eminence of degenerative joints. a
Absent Present Slight Moderate Severe
n % n % n % n % n %
Condylar flattening 9 7.7 108 92.3
Condylar erosion 7 6.0 110 94.0 76 65.0 25 21.4 9 7.7
Condylar osteophyte 24 20.5 93 79.5 65 55.6 24 20.5 4 3.4
Condylar sclerosis 103 88.0 14 12.0 13 11.1 1 0.9 0 0
Subchondral cyst 113 96.6 4 3.4
Sclerosis of the fossa 116 99.1 1 0.9
Flattening of the articular eminence 112 95.7 5 4.3
Condylar hypoplasia 95 81.2 22 18.8
Bifid condyle 116 99.1 1 0.9
Pneumatization 112 95.7 5 4.3
CBCT, cone beam computed tomography.

a n = number of joints.

Bilateral degenerations were detected in 41 patients (54.0%) and unilateral degenerations in 35 patients (46.0%). Hypermobility was detected in 47 (40.2%) degenerative joints and hypomobility in 32 joints (27.4%) ( Table 4 ).

Jan 17, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Temporomandibular joint osteoarthritis: cone beam computed tomography findings, clinical features, and correlations
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