Methods: 3 types of dentures were constructed and tested on the in-vitro model; (i)well-fitted; (ii)over-extended and; (iii) under-extended. Retentive tests were conducted with artificial saliva, using a universal tensile testing machine in an axial pull direction with a speed of 50mm/min with 4 equidistant holding points on the denture occlusal surface. The effect of 3 denture adhesives (PoliGrip®, GlaxoSmithKline; Fixodent®, Procter & Gamble; Super Wernets®, GlaxoSmithKline) on denture retention was also tested on the same denture types at different times over a 5 hour period. Ethical approval was obtained for this study.
Results: The retentive force of the well-fitting denture was significantly greater than for the ill-fitting dentures (P<0.05). With the use of denture adhesives, the retentive force for all three types of dentures increased significantly (P<0.05). Differences were noted between the performances of the adhesives, but no specific trend was observed. The highest retentive forces were recorded for well-fitting dentures used with adhesives (P<0.05). There was no significant difference between the two ill-fitting dentures when adhesives were used (P≥0.05).
Conclusions: There is a good correlation between the in-vitro denture retention results obtained and the in-vivo data reported in the literature. Well fitting dentures give the highest retention values. The in-vitro model developed in this study can be used to test the retention of mandibular complete dentures.