Biomechanical Comparison of Ceramic, Titanium and Chrome Cobalt Post Inlays in Post-Traumatic Dental Defects Repair

Abstract. The aim of the study is the biomechanical substantiation of restoration of tooth crowns destroyed due to trauma using ceramic post inlays.

Materials and research methods. In order to experimentally compare the strength of pin inlays, tooth root and ceramic crown depending on the material of the inlays, three-dimensional mathematical modeling of the stress-strain state of the pin structure using the method of finite element analysis was carried out. The physical and mechanical properties and size of a single-rooted tooth with a fractured crown (upper central incisor), a ceramic crown and a peg inlay made of a chrome-cobalt alloy, titanium or ceramics corresponded to the natural ones. Calculations were performed using the properties of both the devital and the intact tooth. Situations of early operation of the post construction with close contact of the root, inlay, and crown, as well as possible decay of tooth tissues along the edge of the crown in the long-term operation of the construction were simulated. A functional load of 150N was applied to two areas: the incisal edge and the upper third of the palatal surface of the crown on post inlays with a change in load direction from 0 to 90°.

Research results and their analysis. According to the data of mathematical modeling of functional load, the strength of a post-traumatic tooth defect replacement is sufficient when using both metal and ceramic post inlays; changes in physical and mechanical properties of the tooth with increasing time from the moment of devitalization increase stress in the ceramic crown, and root failure along the edge of the crown causes the ultimate stress at a horizontal shift of load direction.

The biomechanical rationale allows: in case of complete destruction of the crown part of the tooth — to recommend milled dowel ceramic inlays as a support of metal-free artificial crowns; to stick to the technology of their fixation in the root canal and of the fixation of crowns to the inlays; to ensure a strict dispensary of patients with a ceramic crown on milled dowel ceramic inlay to detect and to eliminate tooth root caries in the long term; to provide direction of functional load within 30° from the axis of the restored tooth during prosthetics.