Creation and validation of an in-vitro model of an edentulous mandibular ridge for testing mandibular complete denture retention.

The missing teeth of edentulous adults are most commonly replaced with complete upper and lower dentures. The most prevalent problem regarding complete dentures is the retention of the mandibular one. The testing of most denture retention systems has usually employed in-vivo testing with no prior in-vitro tests being carried out. In addition, in-vitro tests that have been carried out did not replicate the natural real situation of the oral cavity. The aim of this study was to design and develop an artificial edentulous mandibular jaw model, with the associated soft-tissue structure (artificial mucosa and reflected tissue) based on real patient parameters, to facilitate testing the retention of mandibular complete dentures. This would enable us to optimise the design and manufacture of novel systems prior to testing on real patients in a clinical trial. The objectives for this study were to firstly conduct a clinical evaluation of patients’ satisfaction with complete denture and to correlate the effect of loose mandibular denture with patient satisfaction. The second objective was to evaluate and identify the most appropriate synthetic materials that would replicate the soft tissue properties. Twelve elastic materials were assessed. These are representative of the following categories of materials: Addition and condensation-reaction silicone, polysulphide, polyether, alginate, maxillofacial impression material, soft lining material and non dental materials-chair side artist materials. Suitable substitute materials to the oral mucosa were used to construct the model. Testing of the model was conducted using a series of protocols to measure and compare the retention of mandibular dentures of varying designs (well-fitting, over- and under-extended) with and without denture adhesives (PoliGrip®, GlaxoSmithKline; Fixodent®, Procter & Gamble; Super Wernets®, GlaxoSmithKline). In conclusion, an in-vitro model of a mandibular ridge can be created to approximate the biophysical characteristics of the covering mucosa, and can be used to assess differences in the retention of various denture designs and different denture adhesives.