الفهرس 
AbstractOnly 14 pages are availabe for public view
 |  | from | 131 |  |  |
| | | from | 131 | | |
Abstract
Aim: The aim of this study was to compare between the stresses induced around the abutments of
removable partial denture retained by conventional extra coronal attachments and that retained by resin
bonded zirconia attachments in Kennedy class I cases.
Methodology: Two acrylic models representing Kennedy class I cases were fabricated with natural
abutments teeth (first and second premolars) bilaterally. The control model abutments were prepared
for full coverage crowns. Conventional extra coronal attachments were fabricated by conventional
casting of CAD/CAM designed wax pattern. The intervention model abutments were roughened
lingually and distally and a rest seat was prepared on the distal side of each second premolar, the
zirconia attachments were then milled from zirconia blocks using CAD/CAM technology. Metal
framework partial dentures were then constructed for both models with nylon caps picked up. A metal
rod was soldered to each framework in the position of the first molars, where universal testing machine
was used to apply vertical load on the first molar unilaterally and bilaterally meanwhile strain gauges
were attached buccally and distally around the abutments on both sides of the arch and connected to a
strain meter to measure the micro strains exerted around the abutments. The right side of each model
was employed as the working side, while the left side was the non working side.
Results: As for the working side, the results revealed statistically significant difference between both
groups, where the zirconia attachment exerted almost half the strain exerted by the conventional metal
attachment. In addition, there was also statistically significant difference between both groups at the
non working side , where the zirconia attachment exerted almost one third that exerted by the
conventional metal attachment.
Abstract
iv
Moreover, as for the central-bilateral loading the results also revealed statistically significant
difference between both groups. The zirconia attachment showed less strain than that exerted by the
conventional metal attachment.
Conclusions: The zirconia attachments showed more favourable stress distribution around the
retaining abutments under all loading conditions which encourages their use as a reliable substitute to
conventional metal attachments.