Objectives: this study was conducted to compare the strains transmitted to the edentulous ridge with two different designs of unilateral removable prostheses using an extracoronal attachment; the unilateral removable partial denture and the unilateral removable porcelain fused to metal bridge.
Materials and Methods: an epoxy resin model with a unilateral distal extension base was prepared to receive a fixed porcelain fused to metal bridge carrying an extracoronal attachment. A unilateral removable partial denture (group I) and a unilateral porcelain fused to metal bridge (group II) were constructed using conventional casting and processing techniques and connected to the extracoronal attachment. Strain gauge was attached to the crest of the edentulous ridge beneath the area of the first molar and loads were applied to each prosthesis separately using a universal testing machine at the beginning of the test (baseline) and after 2000 insertion and removal cycles. Data was collected and statistically analyzed.
Results: a statistically significant difference was found in each group between the mean strain values at baseline and after 2000 insertion and removal cycles. The mean strain values were higher in group II than group I both at baseline and after 2000 insertion and removal cycles, but the difference was not statistically significant.
Conclusions: the unilateral removable porcelain fused to metal attachment retained bridge transfers comparable strains to the edentulous ridge as the unilateral removable attachment retained partial denture. The nylon cap needs to be frequently replaced to avoid excessive strains on the edentulous ridge.