Aim: To study the effects of viscosity of oral moisturizers and residual ridge form on the
retention force of maxillary complete dentures.
Methods: Thirty-five maxillary edentulous participants were recruited. Three types of oral
moisturizers with different viscosities, artificial saliva, and denture adhesive were used. These
were applied between the intaglio surface of the denture and basal seat mucosa. The central
incisor was loaded 45° upward to the occlusal plane. The force needed to dislodge the denture
was measured using a digital force gauge. Dental impressions of the polished surfaces and
intaglio surfaces of the maxillary complete dentures were obtained. Then, duplicate dentures
were cast using auto polymerizing acrylic resin. The buccolingual molar residual ridge form was
assessed using the dental impressions. The duplicate denture was used to measure the positional
relationship of the central incisor edge, anterior residual ridge crest, and posterior border of
dentures. The effect of residual ridge form on retention force was analyzed.
Results: The gel-type oral moisturizer showed significantly greater retention than the
other types (P < .05). The retention force and buccolingual molar residual ridge form were not
correlated. As the ratio of the distance from the central incisor to the anterior residual ridge
crest and the distance from the anterior residual ridge crest to the posterior denture border
increased, retention force decreased (r = -0.352; P < .01).
Conclusion: The results indicate that the retention force of dentures is affected by oral
moisturizer viscosity and the relative position of the anterior residual ridge crest.