Temporomandibular Joint

Thirty two TMJOA patients who underwent unilateral reduction and fixation of temporomandibular joint disc release from March 2021 to March 2022 in the Department of Oral and Maxillofacial Surgery of the Affiliated Dental Hospital of China Medical University were analyzed retrospectively. According to Wikes-Bronstein stages, temporomandibular disorders are divided into five stages. Phase I and II involve the reducible anterior displacement of the articular disc, and phase II has more pain symptoms than phase I. Phase III, IV and V involve the irreducible anterior displacement of the articular disc. Condylar bone destruction occurs in phase IV, and perforation of the articular disc takes place in phase V [14 (link)]. All patients were asked to have a temporomandibular joint MRI examination before surgery.
This study used the following inclusion criteria: (1) the same surgeon performed both the joint disc reduction and fixation; (2) mouth opening training was conducted after the operation; and (3) there was good compliance and follow-up within the prescribed time. The exclusion criteria were as follows: (1) loss to follow up or follow up time < 6 months; (2) a history of temporomandibular joint surgery; and (3) other diseases or mental diseases affecting joint and jaw development.
These 32 patients were asked to receive a chitosan injection two weeks after operation. All patients were analyzed by visual analog scale (VAS) for pain and improvement of maximum comfortable mouth opening before treatment and 6 months after treatment.

This study was a digital retrospective study. For this study, 600 digital OPGs of patients, both male and female aged 21 to 50 years, fulfilling the exclusion and inclusion criteria, were randomly selected from the archives of the department of oral medicine and radiology. The scans were anonymized before the evaluation of the selected parameters. The scans included in the study were of completely dentulous mandibles with proper positioning. The scans that were not included in the study were those where gross deformity of the maxilla-mandibular structures could be seen with any artifacts on the radiograph, any lesions in the mandibular arch that were radiolucent or radiopaque, premolars that were missing, mixed dentition, trauma history and/or ongoing or completed trauma treatment, and radiographic evidence of temporomandibular joint (TMJ) problems. There were two providers involved in collecting the measurements. One was a subject expert with more than 20 years of experience with OPG and its interpretations. The other was a postgraduate student with more than one year of experience in OPG and its interpretation.
A pilot study of 30 scans was done by both observers. The interobserver reliability was assessed through kappa statistics for the degree of agreement. From the overall kappa statistics value, we found out that an almost perfect agreement was achieved between the two providers overcoming any chance of bias and good generalizability. Calibration was then done for both observers, and then the remaining research was completed. Also to eliminate the measurement and provider bias, the analysis of the same anonymized scan was done by both observers twice each with a gap of 15 days.
A total of seven measurements (in mm) were performed on the digital radiographic image (Table 1).
The method of analysis of various parameters was as follows on an OPG (Figure 1).
These parameters were most stable and easy to identify on the mandible. The most convex point on the inferior border of the mandible in the posterior region is the lowest point on the bone. Hence, they were chosen for this study, which had a large sample size of 600 OPGs, after consulting a biostatistician and considering previous studies. These parameters were also considered in a previous study by Indira et al. [2 (link)] and Mostafa and El-Fotouh [13 ] that had a smaller sample size (<100).
The measurements were noted in tabular form. Each gender group was then split into three groups based on age to find out how the parameters of the mandible changed with age. The obtained data for categorical variables was shown as n% of cases, while the data for continuous variables was shown as mean and standard deviation (SD). The statistical intergroup comparison was estimated using the independent sample t-test or unpaired t-test. The statistical comparison of the intergroup distribution of means of continuous variables was also tested using the analysis of variance (ANOVA) procedure. For paired comparisons of means of continuous variables, the paired t-test was used. The linear discriminant function analysis was carried out to obtain a linear combination of various measurements that characterize the two classes of gender. Any underlying normality assumption was evaluated before applying the study variables for the t-test and ANOVA, and P-values < 0.05 were considered to be statistically significant. IBM SPSS Statistics for Windows, Version 21.0. (IBM Corp., Armonk, NY, USA) was used to figure out gender in the statistical analysis.