The Effect of Motivational Interviewing on Oral Hygiene Behavior in Patients With Fixed Orthodontic Appliances: A Randomised Clinical Trial

ABSTRACT: The aim of this study was to evaluate the effectiveness of motivational interviewing on improving oral hygiene behavior in patients with fixed orthodontics appliances. A parallel-group randomized clinical trial was conducted with 45 patients of the Orthodontic Clinic of Unibe's Postgraduate Unit. A computer-generated list of numbers created with SPSS V21.0 was used to randomly allocate participants into the experimental or the control group. Monthly oral hygiene instructions and an oral hygiene kit from GUM® with special orthodontic hygiene tools were given to the participants. Furthermore, the experimental group underwent motivational interviewing sessions facilitated by a periodontist who received training from two expert psychologists. These psychologists also provided supervision to the interviewer, ensuring the accurate implementation of the intervention. Simplified Oral Hygiene Index (SOHI), Gingival Index (GI), Periodontal Probing Depth (PPD) and Bleeding on Probing (BoP) were recorded at baseline, three and six months after the beginning of the study. The participant and the evaluator (another periodontist who recorded the data) were masked. Repeated-measures mixed- model analysis of variance and chi-squared test were conducted. Mean SOHI, GI, PPD and BoP scores did not differ significantly across the three time points (baseline, three and six months). Nevertheless, a significant interaction on SOHI scores (F (2, 58) = 3.463, p = .038, h2 = .052) was found between the sessions and the treatment conditions (experimental vs control group) at the third and sixth month. Motivational interviewing plus oral hygiene instructions appears to maintain a better control of dental biofilm and calculus in comparison with conventional oral hygiene instructions alone.