Background <p>Temporomandibular disorder (TMD) is closely linked to tongue function, yet the dynamic changes in resting tongue parameters (tongue-palate distance and tongue thickness) during TMD rehabilitation remain underexplored. This prospective, non-randomized controlled study aimed to quantify these parameters using ultrasound in TMD patients before and after physical therapy, and compare them with healthy controls, to clarify the therapeutic effect of physical therapy on tongue morphology.</p> Methods <p>30 TMD patients and 30 healthy controls were enrolled. Ultrasound was used to measure tongue-palate distance and tongue thickness in controls once, and in TMD patients both before and after a standardized 2-week physical therapy protocol including thermotherapy, therapeutic ultrasound, transcutaneous electrical nerve stimulation (TENS), and mandibular exercises (3 sessions/week). The Mann-Whitney U test and Wilcoxon signed-rank test were used for between-group and within-group comparisons, respectively.</p> Results <p>Results showed no significant change in tongue-palate distance in TMD patients post-treatment (P = 0.127), but a significant increase in tongue thickness (P &lt; 0.05). Pre-treatment, TMD patients had significantly smaller tongue-palate distance (P &lt; 0.05) and tongue thickness (P &lt; 0.05) compared to controls; post-treatment, these parameters in TMD patients were comparable to controls (tongue-palate distance: P = 0.446; tongue thickness: P = 0.953).</p> Conclusion <p>Physical therapy promotes tongue thickness change and brings tongue-palate distance closer to healthy levels, suggesting ultrasound-quantified tongue parameters could serve as objective indicators for TMD rehabilitation efficacy.</p> Trial registry number <p>ChiCTR2000033328. Registration date: 2020-05-28.</p>