Retention Load and Volume Loss of Telescopic PEEK Crowns with Different Tapers Angles and thickness: in vitro study.

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 determine the retentive force and volume loss at values at baseline and after 3, 6, 9, and 12 months. Data were analyzed by using Statistical Package for Social Sciences P value <0.05(*) was considered a significant difference & P-value <0.001(**) was considered a highly significant difference. Results: Maximum Retentive Load results were analyzed by using mean and standard deviation. repeated measure ANOVA test is used to compare duration in each group in which there is a highly significant difference between durations, also One Way ANOVA test is used to compare groups in each period, while there is no significant difference between groups in each duration. PEEK; secondary crowns exhibit stable retentive force values over 12 months of use showing no signs of deterioration while the retentive force values of electroformed secondary crowns increase over time. Conclusions: Clinical relevance PEEK might be a suitable alternative to proven metallic materials for the fabrication of secondary crowns.