Use of finite element analysis for the assessment of biomechanical factors related to pain sensation beneath complete dentures during mastication

Abstract

Statement of problemThe pain commonly suffered by denture wearers during mastication is not documented in the objective biomechanical criteria for the pressure pain threshold. PurposeThe purpose of this finite element analysis study was to determine whether the pressures developed beneath a removable mandibular complete denture during mastication would exceed the average pressure pain threshold in patients for whom the denture foundation had an acceptable load-bearing capacity. Material and methodsA patient with an acceptable load-bearing denture foundation was modeled with finite element analysis. The denture/mucosa interface was modeled as a sliding or detaching interface. A convex mandibular residual ridge, resilient mucosa, and denture were modeled in computer-aided design (CAD) software using curves and cross sections. A unilateral vertical occlusal load of 100 N was assumed only for model verification, and an oblique mastication load of 141 N was assumed for simulated mastication with balanced articulation. The nonworking-side occlusal contact was simulated in 2 situations: prompt nonworking-side occlusal contact and delayed nonworking-side occlusal contact by setting an initial distance of 0.1 mm or 1 mm between the denture and a flat solid above the nonworking side. ResultsThe denture was held to the mucosa under vertical force and a maximum pressure of 203 kPa. The denture was tilted under an oblique mastication load and achieved stability through nonworking-side occlusal contact. This means that the denture was supported not only by the denture foundation but also by the nonworking-side occlusal contact and had a downwardly directed stabilizing reaction force. The denture was weakly supported on the delayed nonworking-side occlusal contact compared with the prompt nonworking-side occlusal contact and weakly supported on the denture foundation. In delayed nonworking-side occlusal contact, the pressure beneath the denture was 783 kPa (>pressure pain threshold) compared with 484 kPa (<pressure pain threshold) in prompt nonworking-side occlusal contact. Despite the lower reaction force of the foundation in delayed nonworking-side occlusal contact, the pressure beneath the denture increased, indicating a reduction in the load transfer area due to the inclined position of the denture. Friction on the mucosal surface was over 14-fold higher for the delayed nonworking-side occlusal contact. ConclusionsThe pressure beneath a removable mandibular complete denture exceeded the average pressure pain threshold and was supported with a large slide, which produced friction. Although the value of the load on the occlusal side did not change, the pressure under the denture increased and the force of nonworking-side occlusal contact decreased because of increasing distance to nonworking-side occlusal contact.