Evaluation of Retentive Force of Maxillary Complete Dentures with a Gel-Type Denture Adhesive: A Pilot Randomized Crossover Trial

Background/Objectives: A gel-type denture adhesive developed for patients with dry mouth has been shown to increase the retentive force of experimental palatal plates; however, its effect on complete dentures in the oral cavity is unknown. This study compared changes over time in the retentive force of maxillary complete dentures between this adhesive and a conventional cream-type adhesive. Methods: In this pilot randomized crossover trial (jRCT1032240582), 21 maxillary complete denture wearers (11 men and 10 women; mean age, 81.1 years) received a gel-type adhesive for dry mouth (PK) and a conventional cream-type adhesive (NP) in random order on two days 7 days apart. The retentive force of a 3D-printed duplicate denture was measured at 0 min and every 10 min up to 30 min after application, and usability was rated on a visual analogue scale (VAS). Data were analyzed using a linear mixed model with Bonferroni adjustment. Results: A significant treatment × time interaction was observed (p < 0.001). PK showed a significantly higher retentive force than NP at 0 min (difference, 2.37 N; 95% CI, 1.86–2.88) and 10 min (1.00 N; 0.49–1.51). At 30 min, NP showed a higher retentive force than PK (0.63 N; 0.12–1.14), but the difference was not significant after Bonferroni adjustment (p = 0.069); no significant difference was observed at 20 min. PK was rated as less sticky, more moistening, and easier to wash off than NP (p ≤ 0.004). No adverse events occurred. Conclusions: The two adhesives showed different time-dependent patterns of retention: PK provided higher retention immediately after application, whereas the retention of NP increased over time; PK was also rated more favorably for usability. Because most participants did not have clinically defined dry mouth, these preliminary findings are not sufficient to support clinical recommendations, and further studies in patients with dry mouth and over longer periods are needed.