Abstract
The aim of this study was to evaluate the effect of parallel and tapered threaded post placement on the strain and stress distribution of endodontically treated teeth. Fifteen bovine incisors were sectioned 15 mm from their apices, endodontically treated, and divided into three groups (n=5) according to three different threaded posts: parallel threaded post (Radix-Anker, RA); tapered threaded post (Euro-Post, EP) and tapered threaded post (Reforpost II, RII). A strain-gauge was fixed on the proximal surface perpendicular to the long root axis, 2 mm from the cervical limit. Strain generated during post placement was recorded and compared using one-way ANOVA and Tukey's test (α=.05). A scanning electron microscope was used to examine the longitudinal root sections. Stress was evaluated for each group in a two-dimensional finite element analysis. The models were meshed with tetrahedron elements and loaded with 2 N at an angle of 135° to the lingual face. The equivalent Von Mises stress was calculated. The one-way ANOVA showed significant difference among the groups. The RA group (150.0±12.2 A) produced higher external strain than the RII (80.0±12.2 B) and the EP (70.0±6.1 B) groups. The inner strain was approximately five times greater than the external dentin strain. High stress concentrations in each thread of the posts were observed. Scanning electron micrographs showed cracks that started in the threads of the posts. The threaded post placement induced root strain mainly on the parallel side post. Root strain and stress concentration on the post threads tended to create cracks in the inner root canal dentin.
Highlights
IntroductionTreated teeth have higher risk of biomechanical failure than vital teeth.[1,2,3,4,5] The likelihood of a pulpless tooth surviving is directly related to the quantity and quality of remaining tissue.[5,6,7,8] Posts may interfere with the mechanical resistance of teeth, increasing the risk of damage to the residual tooth structure.[9,10,11] The main purpose of a post is to provide retention for the core foundation, when there is an insufficient remaining clinical crown.[12,13,14] The retentive ability and the amount of stress generated during post placement are important factors to consider in post selection. fiber post restorations have shown similar properties to
Oneway ANOVA showed that there was a significant difference in root strain induced by threading of the different posts
High stress concentration in the dentin wall at the thread ends of all posts tested was observed for all models (Figure 2C)
Summary
Treated teeth have higher risk of biomechanical failure than vital teeth.[1,2,3,4,5] The likelihood of a pulpless tooth surviving is directly related to the quantity and quality of remaining tissue.[5,6,7,8] Posts may interfere with the mechanical resistance of teeth, increasing the risk of damage to the residual tooth structure.[9,10,11] The main purpose of a post is to provide retention for the core foundation, when there is an insufficient remaining clinical crown.[12,13,14] The retentive ability and the amount of stress generated during post placement are important factors to consider in post selection. fiber post restorations have shown similar properties to.
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