Effect of Chair Position on Maximum Mouth Opening in Dentulous Patients - An Evaluative Study

Background: Maximum mouth opening (MMO) is a significant clinical parameter in prosthodontics. Although most clinical and research evaluations are performed in the upright position, the procedures are frequently performed at reclined chair positions. Limited data exist on the influence of dental chair positions on MMO. Aim: The study aims to evaluate and compare the differences in MMO between three standardised dental chair positions: upright (90°), semi-supine (120°), and full supine (180°). Materials and Methods: The study involved 60 dentulous participants aged 20–30 years, with definitive criteria. MMO was recorded using a digital vernier calliper across three calibrated positions (90°, 120°, and 180°). Measurements were made thrice in each position, and the mean value was documented. The data was statistically analysed with an established significance level ( P < 0.05). Results: MMO values displayed a gradual increase with 52.38 ± 5.65 mm (90°), 53.82 ± 5.61 mm (120°), and 54.40 ± 5.69 mm (180°). ANOVA displayed insignificance. (F (2,177) =2.03, P = 0.13). Despite a non-significant ANOVA, the Bonferroni-adjusted post hoc tests revealed significant pairwise differences ( P < 0.05) between all positions. Conclusion: Chair positions influence MMO in dentulous individuals. Fixed patient positioning is essential to ensure accuracy and reproducibility in clinical procedures and research involving MMO assessment.