الفهرس 
Prevalence of edendulism and Class I edentulous casesOnly 14 pages are availabe for public view
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Abstract
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This simulation study was conducted to evaluate the stresses induced by CAD-CAM zirconium framework and compare it to a chrome cobalt framework on the supporting structures of Kennedy class I removable partial denture retained with extra-coronal, semi-precision attachments.
Acrylic mandibular model with the first and second premolars bilaterally as abutment teeth was used for this study. This model replicates the anatomic features of the teeth and their investing structures.
The abutments were reduced to 5-6mm in height to provide sufficient tooth reduction with 6 degree taper. The metal crowns with the male part of the extra coronal attachment were fabricated according to conventional casting techniques. Then the chrome-cobalt class I RPD with the female part of the extra-coronal attachment was constructed similarly. The metal crowns and RPD framework were scanned using a CAD-CAM machine to fabricate zirconium crowns and a zirconium RPD framework that were identical to the metal ones.
Two four channel strain meters were used to asses and record the strains induced at the second premolars bilaterally. Strain gauges were installed in a groove created distal to the sockets of the 2nd premolars. A loading device was used to produce a standardized static load within the physiologic limits of 100 N on the first molar area unilaterally and bilaterally.
Summary and Conclusion
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Micro strains were recorded at each site of the strain gauges during posterior unilateral and bilateral loading with enough time between each load to permit complete rebound of the resilient structures.
Based on the data obtained from this experimental in vitro study, it can be concluded that:
The use of zirconium to construct Class I RPD retained with extra-coronal, semi-precision attachments leads to a favourable stress distribution around the abutment teeth.
The use chrome cobalt Class I RPD retained with extra-coronal, semi-precision attachments lead to higher stresses induced on the abutment teeth.
Unilateral loading is more traumatic to the abutments compared to bilateral loading.