Abstract
Objective:
To evaluate the influence of single and double implants on strain distribution of mandibular metal-reinforced overdentures and compare this to a mandibular metal-reinforced complete denture.
Materials and Methods:
Three different scenarios of the same case of an edentulous mandibular model were fabricated: one for a complete denture (CD), one for a single-implant overdenture (1-OD), and one for a two-implant overdenture (2-OD). Ball attachment implants were used for the models 1-OD and 2-OD. A 2-3 mm layer of silicone was created to simulate the mucosa on each model. Linear metal frameworks, following the curve of the arch, were cast in chrome-cobalt alloy from a round-hole chain-shaped preformed wax pattern strip connected to larger holes encompassing each implant matrix site. To measure strain distribution, strain gauges were attached to each denture on the buccal and lingual surfaces of the denture flanges and loaded using five loading scenarios in a universal testing machine.
Results:
Strain evaluation in the single-implant overdenture (1-OD) showed that when the molar teeth were vertically loaded, strain concentration occurred in the premolar area of the same quadrant. This concentration moved towards the midline area as the load moved towards the mesial passing through the premolars to the central incisors. In contrast, the strain evaluation in the two-implant overdenture (2-OD) showed that when the molar teeth were vertically loaded, strain concentration occurred in the midline area. This concentration partially disappeared as the load moved towards the mesial passing through the premolars to the central incisors.
Conclusion:
The current study supports the use of a metal framework as a reinforcement within a two-implant overdenture, but not in a single-implant overdenture. Further experimental investigations are needed to evaluate metal reinforcement within a single-implant overdenture with comparison between reinforced and non-reinforced models.