Photoelastic analysis of stresses transmitted by complete dentures lined with hard or soft liners

Stresses transmitted on the alveolar bone ridge by lined conventional complete mandibular dentures can decrease the bone absorption level. The aim of this in vitro study was to evaluate the stresses induced on the alveolar bone ridge of lined conventional complete mandibular dentures by using photoelastic analysis. One maxillary and three mandibular conventional dentures were developed for the following treatments: 1 - Unlined denture (control), 2 - Denture lined with resin-based material, and 3 - Denture lined with silicone-based material. The photoelastic analysis took place with the dentures in the position of maximum intercuspation, and the mandibular photoelastic models were axially loaded with 10 kgf (98 N). Unlined denture (control) presented stresses along the model, especially on the anterior and left lateral sides with less stresses on the right side. On the left lateral side, the denture base lined with resin-based material demonstrated similar stresses to that of the control; however, lower stresses occurred in the premolar and retromolar regions. Denture bases lined with silicone-based material showed decreased fringe orders and homogeneous distribution of induced stresses. Both lined dentures exhibited lower stresses when compared to unlined dentures. Silicone-based material provided a more homogeneous distribution of stresses.