Cone-beam computed tomographic assessment of the inclination of the articular eminence in patients with temporomandibular disorders and chewing side preference

Background Chewing side preference (CSP) has been proposed as one etiology of temporomandibular disorders (TMDs) as it can induce the structural changes of the temporomandibular joint. But its association with the inclination of the articular eminence (IAE) is unknown. This study aimed to compare IAE between patients with CSP and without CSP. Methods Cone-beam computed tomography images of 90 patients with TMD (mean age of 45.6 years, 69 with CSP, 21 without CSP) and 20 participants without TMD and CSP (mean age of 41.3 years) were measured to compare IAE and depth of the glenoid fossa (DGF) Results IAE and DGF showed a positive correlation among all the participants. Compared with the participants without TMD and CSP, the TMD patients without CSP presented a similar IAE but with a significantly higher value of DGF (p < 0.05); in contrast, the TMD patients with CSP presented a significantly greater IAE and DGF (p < 0.05). No bilateral differences in IAE and DGF were observed in all the participants. Except the male patients with CSP had a deeper fossa than did the female, no differences in IAE and DGF according to gender were observed. Conclusions TMD patients with CSP seem to have a deep glenoid fossa with steep eminence which might be considered one characteristic imaging feature.

The relation between incisal guidance angle and the growth and development of temporomandibular joint: a multi-cross-sectional retrospective study

Background The incisal guidance angle (IGA) is related to temporomandibular joint (TMJ), and changes to the IGA are often involved in the prosthetic and orthodontic treatment of anterior teeth. However, the influence of incisal guidance on the growth, development and remodelling of the TMJ is not yet clear. The aim of this study was to investigate age-related morphological differences in the TMJ in subjects with different IGAs. Methods Cone-beam computed tomography (CBCT) images of 274 patients were included (group 1, IGA < 45°; group 2, 45° ≤ IGA ≤ 60°; group 3, IGA > 60°). Each group was then divided into 4 age groups (group a, 6–12 years; group b, 13–16 years; group c, 17–25 years; group d, 26–33 years). TMJ morphology was assessed by linear measurements, angular measurements, and subjective evaluations. The IGA and occlusal plane angle were also measured. Results Anterior inclination of condyle (AIC) increased with age in the three IGA groups but decreased from 17 years onward in group 2 (P < 0.05). In the age groups analysis, the AIC in group 1 was smaller than that in group 3 but larger than that in group 2 (P > 0.05). Articular eminence inclination (AEI) decreased with age in group 1 (P = 0.027) but increased with age in group 3 (P = 0.053). The AEI in group 2 was larger than that in group 1 at 17–25 years (P = 0.046), and it was larger in group 3 than in group 1 at 26–33 years (P = 0.047). The IGA had a weak correlation with AEI (P < 0.05). Conclusion The articular fossa of patients with shallower incisal guidance changed to a flatter shape with age, whereas the condylar anterior slope and articular eminence of patients with steeper incisal guidance changed towards a steeper alignment. There was a correlation between IGA and TMJ shape.

Evaluation of Articular Eminence Inclination in Normo-Divergent Subjects with Different Skeletal Classes through CBCT

(1) We aimed to compare articular eminence inclination (AEI) in normo-divergent subjects (SN^GoGn = 32° ± 5°), with different anteroposterior sagittal skeletal classes through a cone beam computed generated tomography (CBCT). (2) In this cross-sectional study, CBCT records were retrospectively analysed. From the original sample of 52 CBCT records, 33 records of normo-divergent adult subjects were selected (11 Class I, 13 Class II and 9 Class III). On mid-sagittal section of the Temporomandibular Joint (TMJ) on both sides, AEI was calculated by graphic method. (3) The Kruskal–Wallis test was used to evaluate any difference between AEI on both left and right sides in the three groups. No statistically significant difference was observed on either the right side (p = 0.174) or the left side (p = 0.624). (4) Articular eminence inclination seems to be not related with skeletal class. Given the lack of significance in the observed differences between AEI and skeletal classes, we believe that future studies should focus on assessing possible relationships between AEI and different vertical skeletal patterns.