Effect of preparation design on the fracture resistance of metal free inlay retained fixed partial dentures

Abstract

Although the concept of IRFPD is not new, the general opinion about the prognosis and functionality of such restoration is far from being clear and this had limited its use to highly selective cases making clinicians reluctant in presenting IRFPDs as a restorative option for their patients. However; careful case selection, design preparation, material used and treatment planning can improve the clinical success of IRFPD. For proper selection of IRFPD’s material, it is necessary to know to what extent this material can resist dislodging forces without de bonding and withstand masticatory forces without fracture, thus both forces had to be studied. This study was performed to evaluate the effect of different of two design preparations and two different free metal dental materials for IFPD fabrication on the fracture strength of IFPD. This in vitro study used twenty eight models of IFPD of epoxy resin. missing upper second premolar, divided into two main groups of two different preparations full inlay design & box shape design n=14 for each group: Group A: inlay-shaped preparation design Group B: box – shaped preparation design then each group divided to two sub groups (n=7) according to the material of construction Subgroup 1: all-ceramic material: lithium disilicate glass ceramic Subgroup 2: high-performance polymers: (Bio- HP) Samples of all groups were cleaned with distilled water in an ultrasonic unit for approximately 1 minute. They were then rinsed thoroughly with water spray and dried with oil-free air. Then all IFPDs were cemented adhesively to their respective epoxy-resin models using, a dual cure adhesive resin cement