|Year : 2021 | Volume
| Issue : 1 | Page : 6-11
Assessment and comparison of condylar position based on joint space dimensions and gelb 4/7 grid using CBCT
Sairam Vankadara, Baandhavi Akula, Kolluri Nissi
Department of Oral Medicine and Radiology, G. Pulla Reddy Dental College, Kurnool, Andhra Pradesh, India
|Date of Submission||31-Oct-2020|
|Date of Decision||09-Feb-2021|
|Date of Acceptance||16-Feb-2021|
|Date of Web Publication||26-Mar-2021|
Dr. Sairam Vankadara
Professor and Head of the Department, Department of Oral Medicine and Radiology, G Pulla Reddy Dental College, Kurnool -518007, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Temporomandibular joint (TMJ) is a unique joint. An optimal position of the mandibular condyle in the glenoid fossa is a fundamental question in dentistry, and there is no quantitative standard. Thus, the most common condylar position in the glenoid fossa can be determined by the dimension of the joint space and Gelb 4/7 grid using cone-beam computed tomography (CBCT). Aim: To analyze the position of the condyle and joint spaces in the normal temporomandibular joint and to compare the efficacy of the Gelb 4/7 grid over dimensions of joint spaces to assess optimum condylar position using CBCT. Materials and Methods: CBCT images of 40 patients (right and left) without a history of TMJ disorders were selected. Anterior (Ajs), superior (Sjs), and posterior joint spaces (Pjs) on sagittal slices, medial (Mjs), and lateral (Ljs) on coronal view were measured and Gelb 4/7 grid on sagittal slices used to assess the condylar position. Results: Significant difference between right and left sides in Ajs, Sjs, Mjs, and Ljs values. Significant differences were noticed in Mjs, Ajs values between males and females. Centric position is the most common position of the condyle, and 4/7 position is the most common according to Gelb 4/7 grid. Conclusion: Gelb 4/7 position was found to be the most common anatomical position of the condyle in healthy TMJs, and centric relation position was the most common based on joint space dimensions.
Keywords: CBCT, Centric position, Gelb 4/7 position, joint spaces, temporomandibular joint
|How to cite this article:|
Vankadara S, Akula B, Nissi K. Assessment and comparison of condylar position based on joint space dimensions and gelb 4/7 grid using CBCT. J Indian Acad Oral Med Radiol 2021;33:6-11
|How to cite this URL:|
Vankadara S, Akula B, Nissi K. Assessment and comparison of condylar position based on joint space dimensions and gelb 4/7 grid using CBCT. J Indian Acad Oral Med Radiol [serial online] 2021 [cited 2021 Aug 3];33:6-11. Available from: https://www.jiaomr.in/text.asp?2021/33/1/6/312207
| Introduction|| |
The temporomandibular joint (TMJ) is unique, formed by fitting the mandibular condyle into the glenoid fossa. In the resting position, the articular disc lies at a superior portion relative to the head.,, Centric relation and neuromuscular position are currently the running philosophies of the healthy TMJ position, and there is no quantitative standard for the prime position., For repositioning the mandible in internal derangements and different types of malocclusion, Harold Gelb, in 1953, first described an orthopedic technique that correlates with the normal physiologic position of the mandibular condyle in the glenoid fossa. There are so many imaging modalities to visualize TMJ, and cone-beam computed tomography (CBCT) is an advanced technique., Thus, the most common condylar position in the glenoid fossa can be determined by the joint space and Gelb 4/7 grid dimension. According to GPT-9, centric relation is defined as a maxillomandibular relationship independent of tooth contact, in which the condyles articulate in the anterior–superior position against the posterior slopes of the articular eminences. So, the purpose of the present study was to analyze the position of the condyle and joint spaces in the normal TMJ and to compare the efficacy of the Gelb 4/7 grid over dimensions of joint spaces to assess optimum condylar position using CBCT.
| Material and Methods|| |
The study consisted of 40 patients, both men and women aged 25–45 years, who visited the Department of Oral Medicine and Radiology. The written informed consent was taken from every patient before they participated in the study.
Sample size estimation was done as per the formula below:
S is Standard deviation of sample mean.
Hence S is Sd (sample mean).
S (sample mean) =23
Za =1.96 i.e. 95% of C.I.
d = 5 % presision
n (sample size) = [Z2 S2] /d2
= [(1.96)2 (23)2] / 52
= [3.8416 + 529] / 25
Hence, 22 patients can be included
- Patients with skeletal class I malocclusion and complete dentition, excluding third molars, were included in the study,
- CBCT images of the patients without any TMJ pathologies,
- CBCT images of the patients without any procedure-related, introduced, and patient motion artifacts were included in the study.
- Pregnant ladies,
- Patients with a history of recent trauma to the maxillofacial region, pain, joint sounds, clenching, and limitation in the range of motion were excluded from the study,
- Patients with severely attrited teeth,
- Patients with skeletal class II and class III malocclusion,
- Edentulous patients (even with a loss of single molar),
- Patients with endocrine disorders affects the TMJ and medically compromised patients,
- Patients with conditions affecting bone metabolism,
- Patients using medication that interfere with bone turnover,
- Patients who are not willing for radiographic examination were also excluded from the study.
Subjects in the study and procedures followed were under the ethical standards of Helsinki Declaration (2013), and the clinical protocol for the study was approved by the Institutional Ethics Committee (GPRDCH/IEC/with number 020 dated 01.12.2018).
All the patients in the study were evaluated clinically after taking their detailed history. The TMJ evaluation was evaluated using bimanual and bidigital palpation of masticatory muscles and TMJ in an extra oral examination and auscultation of the joints to rule out temporomandibular disorders (TMDs). An intraoral examination was done for assessing complete dentition. The procedure was explained briefly, followed by the attainment of informed consent from the patient. Then they were subjected to CBCT investigation using Care stream 9100 CBCT, by following ICRP guidelines and then assessed in a device using Care stream software. CBCT images were taken for the purpose of other than this study (such as for endodontic therapies and for assessment of third molar position).
Selected subjects were positioned in the CBCT unit so that the vertical line produced by the CBCT unit was aligned with the facial midline and the horizontal line (Frankfort horizontal plane) was parallel to the floor. Head alignment and subjects positioning were within the reviewer's standard range of quality. Then subjects were exposed using a Care stream 9100 CBCT machine with 8 × 8 FOV, at 120 kVp, 3.8 mA, and a three-dimensional reconstruction screen used to scroll through axial, sagittal, and coronal planes. Images were then assessed in a laptop with Intel (R) core ™ [email protected], with a DVD drive and display properties of 64-bit operating system ×64 based processor with 4GB RAM. Digital images obtained in the system were then analyzed for TMJ.
At first, on axial slices of the CBCT image, the condylar head's largest mediolateral dimension was selected. Then on sagittal slices, a horizontal line was drawn on the uppermost area of the glenoid fossa. The distance between its superior reference point and the prominent superior point of the condylar head of the condyle was noted as superior joint space (Sjs). Sequentially, the superior reference point of the glenoid fossa connected with the prominent points present on the anterior and posterior surface of the condyle, and their distance was considered as anterior and posterior joint spaces (Ajs, Pjs) respectively [Figure 1].
On coronal slices, the tangential lines drawn along medial and lateral slopes of the fossa and connected with the lines which are perpendicular drawn from the most prominent points on the medial (M) and lateral (L) poles of condylar head and their distances were measured as medial joint space (Mjs) and lateral joint space (Ljs), respectively [Figure 2]. Then on sagittal slices of CBCT images to form a Gelb 4/7 grid, three parallel and two perpendicular lines were drawn. The first line is drawn tangentially to the top of the glenoid fossa. The second line at the bottom parallel to the first, and the third line divides the distance between two lines. The first perpendicular line was drawn from the superior most point of the fossa and the second from the intersection between the fossa's slope and the third horizontal line and then forms seven grids named as 1—7 [Figure 3].
The data obtained was entered in the Microsoft excel sheet. Data analysis was carried out using the Statistical Package for Social Sciences (SPSS) version 21. Basic descriptions were presented in the form of mean and standard deviation. Difference between left and right sides was done using “paired t-test.” To assess age and gender different “independent sample t-test” was used. The level of significance was set at*P < 0.05 (significant), **P > 0.05 (Not significant) for all tests. Inter- and intra-examiner reliability was assessed using intra-class correlation coefficient (ICC).
| Results|| |
In this study, among 40 patients, 23 were women, and 17 were males with a mean age of 34.3 years. No significant difference was noticed in the values of total joint spaces [Table 1] and their ratios [Table 2] between different age groups. In between males and females, a significant difference was noticed among the mean values of Mjs and Ajs [Table 3], and a significant difference noticed in M/L joint space ratios, respectively [Table 4]. A significant difference was noticed among the mean values of Mjs, Ljs, Ajs, and Sjs [Table 5], and no significant difference between the ratios of joint spaces in between right and left sides noticed [Table 6]. There was an excellent intra- and inter-examiner reliability. According to the centric relation philosophy, the centric position of the condyle (85% on the left and 82.5% on right) is the most common, followed by the anterior position (12.5% on the left and 10% on the right) and then the posterior position (2.5% on the left and 7.5% on the right). According to neuromuscular position philosophy, Gelb 4/7 position was the most common condylar position in both right (92.5%) and left (95%) sides. 7.5% showed a 2/5 position on the right side and 5% on the left side.
| Discussion|| |
TMJ, the only movable component in the craniomandibular complex, is a compound joint involving the three components condylar process of mandible, glenoid fossa of temporal bone, and avascular fibrocartilage articular disc of variable thickness. The median portion of the disc is thin when compared with the anterior and posterior band. Generally, in the resting position or when the jaw is closed, the posterior band of the articular disc lies at the superior position, that is, at 12'0 clock position relative to the head.,,
Centric relation and neuromuscular position are the currently running philosophies of the healthy TMJ position. Over the past half-century, the definition of centric relation has evolved from being a superior posterior position to a currently superior or anterosuperior position. For many dentists, the inferior forward is the only position of neuromuscular position. The optimal position of the mandibular condyle in the glenoid fossa is always a fundamental question in dentistry. There is no quantitative standard for the prime position of the mandibular condyle in the glenoid fossa. Dalili Z et al. concluded that the condyle's most common position in the fossa is a centric position in the normal TMJs of skeletal class I subjects.
The joint space is an entirely radiographic term which describes the radiolucent area between the condyle and mandibular fossa. Many imaging modalities have been developed to visualize condyle morphology, position, and joint spaces, and degenerative signs symptoms of TMJ disorders. Patient's clinical evaluation is considered a diagnostic tool to assess the TMJ alterations supplemented by investigations such as TMJ tomography and magnetic resonance imaging (MRI). With the advent of the cone-beam computed tomography (CBCT) in 1990's having the advantage of the low dose and without superimposition of bony structures, the most frequently used, simple, cost-effective, conventional TMJ views like Transcranial and Trans pharyngeal radiography are of limited interest now.
CBCT, a 3D imaging modality provides multiplanar images that allows for the accurate assessment of the condyle position within the glenoid fossa and the dimensions of joint spaces. This technique provides images in three anatomical planes (axial, sagittal, and coronal planes), providing easier visualization of the TMJ. Barghan S et al., Tsiklakis K et al., TA Larheim et al. reviewed that CBCT is an advanced technique that provides multiplanar images with high resolution and low radiation dose compared with that of computed tomography (CT) and can visualize TMJ anatomy without any distortion superimposition, which facilitates the analysis of joint spaces in all dimensions and are reliable to evaluate joint space's linear measurements and also to assess the shape and position of the condyle. Soumalainen et al and Kobayashi et al., found that the accuracy of assessing linear measurements was greater and also the errors are less in CBCT than CT.
In the present study, no significant age difference was noticed in the dimensions of total joint spaces. This study is consistent with the study by Mahmood HA et al., where they noticed no significant age difference in any of the joint space measurements. But, significant differences were noted in Mjs, Ajs values, and there was no significant difference in P/A and S/A ratio between males and females. The present study is in agreement with that of Dalili Z et al. in terms of significant gender difference, observed in the P/A and S/A ratio but not insignificant joint space difference. This study values the P/A ratio and S/A ratio are 1.4 and 1.9, respectively, without a significant difference in Sjs, Pjs, and values between males and females. This study is consistent with Ikeda K et al. that noticed P/A ratio and S/A ratio 1.6 and 1.9, respectively, and no significant difference in Sjs, Pjs, and values between males and females.
In the present study, significant sex differences were noticed in Ajs. This is in accordance with the values of Al-koshab M et al., Kinniburgh RD et al. wherein they observed a significant difference in Ajs between males and females. In our study, Sjs value is more significant in males than females, which is consistent with Al-Rawi NH et al., where they noticed Sjs value greater in males than females.
Significant differences were noted in Ajs, Sjs between right and left sides, and P/A ratio of 1.28 and 1.41, respectively, these results are consistent with the study of Cohlmia JT et al., where they noticed a significant difference in Ajs, Sjs among right and left sides, and P/A ratio 1.18 and 1.34, respectively. The insignificant difference in Pjs between right and left sides of our study are consistent with that of Manjula WS et al., Kecik De et al., and Kikuchi K et al. Similar to our study Dalili Z et al., observed significant differences in Ajs, Sjs, Pjs, Mjs, and Ljs values between right and left sides.
The value of Sjs observed in our study was greater than Pjs and Ajs in both genders and sides is in agreement with the study by Al-koshab M et al. and Major et al., The outcome values of our study were more significant than Dalili Z et al. and Ikeda K et al., and almost similar to Kinniburgh RD et al., in terms of Pjs in between males and females.
There is always controversy regarding the three-dimensionally reposition of the mandible in internal derangements and different types of malocclusion. For this condition, Harold Gelb in 1953, first placed the condyle in the Gelb 4/7 position within the glenoid fossa by describing his mandibular orthopedic repositioning appliance to improve clicking, locking, and shearing forces suggesting that Gelb 4/7 position correlates with the normal physiologic position for the TMJ condyle in the fossa.
In the present study, the centric position was the most common position of the condyle (85% on the left and 82.5% on the right), followed by the anterior position (12.5% on the left and 10% on the right). Then the posterior position (2.5% on the left and 7.5% on the right) and similar results were observed by Dalili Z et al., Wiese et al., and the study conducted by Kecik De et al., also reported similar, that the condyle was positioned centrally in most TMJs. Alexander et al. stated that the most common position of the condyle in glenoid fossa is the posterior position in a symptom-free population of half of the patients with the anteriorly displaced disc. Incesu et al. observed a posterior condylar position in patients with TMJ disorder. Seren et al. reported that Ajs was smaller in the patients with class III malocclusion than class I and indicated that the condyle's anterior position is more frequently observed in class III patients and suggests that centric position is the most common in class I malocclusion. Gateno et al. analyzed the mandibular condyle head position in the glenoid fossa and concluded that the condyle's position was more posterior and superior in the patients with anterior disc displacement when compared with the normal group and the centric position is the most common in the normal group.
In the present study, Gelb 4/7 position was the most common condylar position in both right (92.5%) and left (95%) sides; 7.5% showed a 2/5 position on the right side and 5% on the left side. Simmons III HC stated in his paper that neuromuscular stimulation and therapy as one of the treatment modality for craniofacial pain. There is an opinion that the Gelb 4/7 position of the mandibular condyle correlates with the normal physiologic position of the TMJ condyle in the glenoid fossa. So the present study was planned to assess the TMJ condylar position in the glenoid fossa using Gelb 4/7 grid. No literature was found based on this concept, and we think this is the first study where we used the Gelb 4/7 grid in CBCT to assess the condylar position based on neuromuscular philosophy.
Limitations and future prospects
The limitations of the present study are short study sample which cannot exhibit accurate result. Only healthy subjects with skeletal class I malocclusion were included in the study, with the age groups range from 25 to 45 years. Among 40 patients, female subjects were more in the study when compared with the males. Diseased patients were not included in the study to differentiate the condyle's position in between healthy TMJs and diseased.
Although our study gave a clear view of the most common TMJ condylar position in the glenoid fossa of human healthy TMJ's by measuring joint spaces and by using Gelb 4/7 grid, further studies are indicated with larger sample size and a comparison with the skeletal Class II and class III malocclusion is needed. Furthermore, a comparison of healthy TMJs with the disease is advisable.
| Conclusion|| |
According to neuromuscular philosophy, the present study concluded that the Gelb 4/7 position, centric position according to centric relation philosophy, is the most common anatomical position of the condyle in healthy TMJs of our test subjects. Radiographs play a significant role in TMJ analysis, wherein accurate joint space analysis can only be performed through three-dimensional imaging. Variations in the dimensions of joint spaces and the GELB 4/7 grid were active indicators for diagnosing TMDs. Thus, according to neuromuscular philosophy, our study emphasizes that Gelb 4/7 grid is an alternative and provides a more accurate condylar position in the glenoid fossa than centric relation philosophy. GELB 4/7 grid can be used as an alternative for assessing the TMJ condylar position in the glenoid fossa.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]