The Effect of the Different Computerised Telescopic Crowns Materials on the Supporting Structures of Unilateral Free-End Saddles

Abstract

Background and Objectives: Unilateral free-end partial edentulism represents a challenge in prosthodontics due to the unfavorable load distribution on the last abutment and other supporting natural structures. Telescopic crown retained partial dentures are one of the solutions to improve stress distribution more evenly, and this study aims to evaluate the effect of two different materials used in the construction of these appliances, PEEK and metal (titanium), on stress distribution around the abutment and supporting natural structures, as well as the site of applied stress. Methods: a vertical static load of 100 N was applied on Kennedy class II mandibular casts, which were fabricated from PEEK and metal materials on two locations: tooth #45, which was the last abutment, and tooth #46, which was replaced on the free end saddle to compare microstrain using strain gauge rosettes positioned distal to the abutment and on the residual ridge. Results: telescopic crowns made from titanium showed significantly higher micro-strain values than PEEK (p = 0.0001), especially distal to the abutment (p ≤ 0.0001). The application of the load on the free-end saddle resulted in a higher microstrain value compared to the load on the abutment, p ≤ 0.0001. And no statistical difference was observed between the two materials in the value of microstrain when the load was applied to the free-end saddle, p = 0.08. Conclusions: Telescolic PEEK crowns might provide a more favorable stress distribution around the abutment and free-end saddle in Kennedy class II edentulous patients, while metallic crowns will provide greater rigidity to the prosthesis.