Stress Distribution in Maxillary Central Incisors without Ferrules: A Finite Element Analysis of Post and Core Systems

Abstract

Purpose: The purpose of this study was to identify optimal post and core materials for central incisors without ferrules using three-dimensional finite element analysis and three-point bending tests. Methods: Stress analyses were performed with six models: cast metal post and core (MP), composite resin core alone, straight fiber-reinforced post-composite resin core (FSR), tapered fiber-reinforced post-composite resin core, straight titanium postcomposite resin core (TSR), and tapered titanium post-composite resin core (TTR). A 100-N load was applied to the lingual surface at a 45˚ angle to the long axis of the tooth. Maximum von Mises stress distributions were calculated with finite element analysis software. Five samples each of composite resin, straight fiber-reinforced post, straight titanium post, straight fiberreinforced post and composite resin, and straight titanium post and composite resin were subjected to three-point bending tests, followed by analysis of variance and Tukey's multiple comparison test. Results: Stress distribution was optimal on TTR. Maximum von Mises stress on the cervical side of the post was greatest in TSR (693 MPa) and TTR (556 MPa). Maximum stress on the apical side of the post was greatest in MP (110 MPa). Maximum stress in surrounding dentin was lowest in MP (203 MPa) and TTR (250 MPa). Gap distance was smallest in MP (0.09 mm) and largest in FSR (0.26 mm). Mean maximum three-point bending force was lowest in composite resin (26.9 N/mm) and highest in titanium post and composite resin (97.1 N/mm). Titanium post bending strength was consistently greater than that of the fiber-reinforced post (p < 0.01). Conclusion: These results revealed optimal stress distribution and high bending strength with the tapered titanium post and resin combination, suggesting that this combination can most effectively prevent root or post fracture in an anterior tooth without a ferrule.

Effect of Ferrule Design on Stress Distribution of Maxillary Incisor Rehabilitated with Ceramic Crown and PEEK Post–Core Material: A 3D Finite Element Analysis

“…This alignment between experimental and FEA estimations has established FEA as a reliable method for assessing stresses in post-core restored teeth. As a result, several studies [15,16,18,29,31,[34][35][36][37][38], including the present one, have utilized FEA to evaluate post-core systems. A large variety of materials have been evaluated to produce prefabricated posts and post-core structures [34].…”

“…To simulate a normal occlusion, a static load of 100 N was applied at a 45-degree angle to the long axis of the tooth on the Lingual side of the clinic crown [27,33], 2 mm from the incisal edge, as depicted in Figure 4. For each experimental clinical scenario, von Mises stress data were collected [18]. The peak stress values and locations, as well as the plot contour for stress distribution behavior for the ceramic crown, root-ferrule, and post-core layers, were recorded and further analyzed.…”

“…Although studies have concluded that the design of the ferrule does not exert an influence on the biomechanical performance of endodontictreated incisor teeth [10,12], there is consensus that the presence of an incomplete ferrule is considered a better option than the complete lack of it [9,13,14]. Many studies have assessed the impact of different ferrule heights [14][15][16] and the influence of the post material [1,17,18] in the development of non-reparable (below the cement-enamel junction-CEJ-leading to tooth extraction) or reparable (above CEJ) tooth fractures [8,19]. However, there are a lack of studies testing incomplete ferrule designs and their interaction with one-piece post-core made of PEEK related to the stress distribution of human maxillary incisors rehabilitated with monolithic zirconia crowns; thus, these are the parameters tested in this study.…”