Effectiveness of HAPA-based oral hygiene instruction in patients over 65 years of age: a randomized controlled trial

The aim of the study was to provide oral hygiene instructions tailored to behavioral stages based on the Health Action Process Approach (HAPA) and to assess their impact on oral health compared with standardized instructions in patients aged 65 and older. A total of 67 university clinic patients were randomly assigned to an intervention (n = 33) and a control group (n = 34) and 62 patients, aged 65 to 87 years (M = 71.3, SD = 5.3), participated in both the baseline and the follow-up visit. To assess oral hygiene, the parameters Gingival Bleeding Index (GBI) and Plaque Control Record (PCR) were recorded at baseline and 12 weeks after instruction. In the intervention group, a questionnaire was used at the beginning of both visits to survey oral hygiene behavior and motivation to change behavior. For both groups, the first visit included a survey on oral hygiene parameters followed by either HAPA-based or standard instruction with demonstration of oral hygiene aids. Analyses of covariance with baseline control revealed no difference in GBI between the intervention and control group at the 12-week follow-up. Both the intervention group, t(29) = 3.91, p <.001, d = 0.71, as well as the control group, t(31) = 3.67, p <.001, d = 0.65, demonstrated significant improvement in GBI. In contrast, only the intervention group showed a significant improvement in PCR at reevaluation, t(29) = 2.29, p =.03, d = 0.42. Additionally, the intervention group reported a significant increase in motivation and the frequency of interdental care, t(29), 6.67, p <.001, d = 1.22. This study provides first evidence on the HAPA model being effectively applicable in the context of dental prophylaxis among university clinic patients older than the age of 65. A positive effect on patients’ behavior and oral hygiene could be demonstrated. While general instruction proved effective in reducing gingival bleeding, the theory-based HAPA intervention offered specific advantages in motivation, interdental care, and plaque buildup. German Study Register of Clinical Studies (DRKS, ID DRKS00030040, German Clinical Trials Register, Date of registration 22.03.2023).