# A retrospective study of remodeling changes of the temporomandibular joint structures in patients with unilateral posterior tooth loss

## TL;DR

This study examines how losing a back tooth on one side affects jaw joint structures and finds that the joint changes depend on factors like how long the tooth has been missing and chewing habits.

## Contribution

The study identifies specific biomechanical impacts of unilateral posterior tooth loss on TMJ structures based on duration and chewing behavior.

## Key findings

- Glenoid fossa and joint spaces enlarge after unilateral posterior tooth loss.
- Shorter tooth loss duration (<1 year) leads to larger posterior joint spaces on the contralateral side.
- Unilateral chewing reduces condylar diameter on the preferred chewing side.

## Abstract

This study aimed to enhance understanding of how unilateral posterior tooth loss (UPTL) affects temporomandibular joint (TMJ) structures and to explore potential influencing factors on joint morphology.

The study included 68 subjects (34 patients with UPTL and 34 with complete dentition), divided into the missing group (n = 34 joint sides), the contralateral group (n = 34 joint sides), and the control group (n = 68 joint sides). Morphological measurement of the condyle, glenoid fossa and joint spaces were performed using cone-beam computed tomography (CBCT) and Mimics software. Analyses and comparisons were made among the three groups, with subgroup analyses based on the duration of tooth loss (< 1 year and ≥ 1 year), first molar loss, and the presence of unilateral chewing habit (UCH).

Some significant differences among the control, the missing, and the contralateral groups were observed in measurements of the glenoid fossa and joint spaces (P < 0.05). When tooth loss lasted less than 1 year, the contralateral side exhibited significantly larger posterior joint spaces than the missing side (P < 0.05), whereas no differences were observed at ≥ 1 year. In the first molar loss subgroup, the anteroposterior and mediolateral diameters of the glenoid fossa were significantly larger on the contralateral side than on the missing side (P < 0.05). Moreover, unilateral chewers with UPTL exhibited significantly smaller anteroposterior condylar diameters on the preferred chewing side (P < 0.01).

An overall enlargement of both the glenoid fossa and joint spaces was observed in patients following UPTL; the glenoid fossa was found to be more susceptible to bone resorption than the condyle. Factors such as the duration of tooth loss, the absence of the first molar, and UCH contribute variably to these structural changes, indicating that different tooth-loss conditions can impose distinct biomechanical impacts on the TMJ.

The online version contains supplementary material available at 10.1186/s12903-025-07594-8.