Evaluation of Stress Distribution of Zirconium Versus PEEK Extra Coronal Attachment on Supporting Structures of Lower Kennedy Class II Partial Denture (In vitro study)

Abstract

This study was conducted to assess and compare the stress distribution on supporting structures induced by PEEK versus zirconia materials used as an extra coronal attachment of removable partial denture in Kennedy class II. A mandibular Kennedy class II model was digitally scanned. Sound natural canine and first premolar teeth were prepared and scanned. On the software, the canine and the first premolar were removed from the cast, then virtual superimposition of the scanned natural teeth were done. Two strain gauge slots were designed on the software to receive the strain gauge rosettes. The first one (slot I) was placed 1mm distal to the socket of the first premolar and the second slot (slot II) 1 cm distance away from the first one. Two models and two sets of teeth were 3D printed. The 3D printed teeth were then scanned. The attachment design was selected from software library. The crowns and selected attachment design were digitally designed. The lingual surface of the first premolar crown was prepared to receive lingual guiding arm. Crowns and attachment were milled out of zirconia and PEEK materials. Five RPDs were constructed for each model. The strain gauges were installed in their grooves on the distal aspect of the abutment and the crest of the ridge. The magnitude