Minimal clinically important differences of oral health-related quality of life after removable partial denture treatments

Objectives: This study aimed to determine the minimal clinically important difference (MID) of the oral health-related quality of life (OHRQoL) in removable partial dentures (RPDs) wearers, using the oral health impact profile (OHIP). Methods: In this study, RPD patients were asked to complete the OHIP and self-reported oral health (SROH) questionnaires before the treatment and 3 months after the RPD treatment. The Wilcoxon signed ranked test compared the pre- and post-treatment status and the Spearman correlation analysis evaluated the relationship between the pre- and post- treatment change scores of the OHIP and SROH. The median OHIP change score in a subgroup that showed minimum SROH improvement was determined as the MID. Results: Of the 277 participants, 248 (89.5 %) completed the pre-and post- treatment evaluations. SROH and OHIP scores showed significant improvements after RPD treatment (P<0.05). The OHIP change scores showed significant moderate correlations with the SROH change scores (P<0.05). The MIDs for the summary scores of OHIP-49, 20, 14, and 5 versions were 14, 7, 3, and 2 points, respectively. An additional 2-3 points were assigned to the four dimensions (oral function, orofacial pain, orofacial appearance, and psychological impact). Conclusions: An OHIP change of more than 14 points (OHIP-49), 7 points (OHIP-20), 3 points (OHIP-14), 2 points (OHIP-5) and 2-3 points (4 dimensions) was considered clinically meaningful in RPD treatments. Clinical Significance: The proposed MID scores could be used as a benchmark for clinical decision making, interpretation of RPD treatment effects on OHRQoL, and sample size calculations in clinical trials.