الفهرس 
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Abstract
This simulation study was conducted to determine and compare the effect of number of abutment teeth on stresses transmitted to the overdenture supporting structures using strain gauge technology.
Two mandibular overdentures supported by clip bar attachment were constructed on two acrylic experimental mandibular models. The 1stmodel (model I) was having two canines as abutment teeth, while the 2nd model (model II) was having the two canines and the right central incisor as abutment teeth. These models replicate the anatomic features of the teeth, their investing structures and the mucosa covering the ridge.
The abutment teeth of the two models were reduced into dome shaped preparation 1 to 2 mms above gingival margin. The abutment teeth of each model were connected with bar, that was engaged by the denture through clips.
Four channel strain meter was used to record the strains induced in the supporting structures of each overdenture (the abutment teeth and residual ridge).Two strain gauges were installed 1 mm distal to the abutment teeth (the two canines). The other two gauges were installed vertically on the buccal side of the residual ridge at the second molar area.
A loading device was used to produce a standardized static load within the physiologic limits (100N) on the second premolar and second molar area bilaterally and unilaterally.
Microstrains were recorded at each site of the strain gauges during bilateral and unilateral loading with enough time elapsed between each two successive loadings to allow complete rebound of the resilient structures of the model.
The results of this study revealed that, statistically significant lower stresses transmitted to the supporting structures (abutment teeth and ridge) of model II (three abutments overdenture) than that of model I (two abutments overdenture).
The results of this study revealed also statistically significant increase in the stresses transmitted to the abutment teeth when the load was applied on 2nd premolar tooth compared to the stresses transmitted to the abutments when the load was applied on 2nd molar tooth. However statistically significant more stresses transmitted to the residual ridge when the load was applied on 2nd molar tooth than when applied on 2nd premolar.