Objective:The aim of this study was to investigate the Retention force and Volume Loss of CAD/CAM-fabricated polyetheretherketone (PEEK) telescopic crowns which with different Tapers and Thicknesses.Material and methods: Peek primary crowns (N = 5) were CAD/CAM milled and provided with secondary crowns CAD/CAM-fabricated PEEK secondary crowns (group N = 5).The universal testing machine was used to...