Abstract
Introduction Restoration of immature teeth with open apices and thin dentinal walls with conventional post systems remains a challenge. The purpose of this study was to evaluate the fracture resistance of simulated immature teeth restored with different intraradicular posts and assess their stress distribution pattern using 3D Finite Element Analysis (FEA). Methods Fracture strength testing using universal testing machine was carried out in simulated immature teeth restored with different intraradicular posts grouped as follows: Group A: teeth not restored with posts served as control group; Group B: Cast metal post (CMP); Group C: Customized Composite Post (CCP); Group D: Fiber post (FP). Four 3D FEA models of the above groups were created using CATIATM software and analyzed for stress distribution using ANSYSTM. The results of fracture strength testing and FEA were correlated. Multiple group comparisons were analyzed by one-way ANOVA followed by Tukey HSD post hoc test. Results The CMP exhibited highest fracture resistance (336.43 N) but resulted in root fractures. The CCP exhibited lower fracture resistance (240.90 N) and favorable stress distribution as compared to CMP. The FP and control group exhibited lower fracture resistance values of 182.69 N and 130.46 N, respectively. The results of 3D FEA demonstrated higher stress concentration in model comprising metallic post and core. Conclusions Teeth restored with cast metal posts and cores exhibited maximum fracture resistance followed by the customized composite posts, the fiber posts, and the control group. The cast metal posts indicated higher von Mises stresses concentrated in the radicular region; however, the customized composite posts, the fiber posts, and the control group demonstrated stress concentration in the coronal region.
Highlights
Restoration of immature teeth with open apices and thin dentinal walls with conventional post systems remains a challenge. e purpose of this study was to evaluate the fracture resistance of simulated immature teeth restored with different intraradicular posts and assess their stress distribution pattern using 3D Finite Element Analysis (FEA)
All the samples presented with fracture of the coronal tooth structure (Figure 3(a)). e Group B-simulated immature teeth restored with cast metal post and core exhibited highest mean resistance of 336.43 N
Results of this study indicate that cast metal post has highest fracture resistance. e inherently high modulus of elasticity enables the post to withstand deformation forces generating high stress concentration at interfaces [32, 33]. e teeth restored with customized composite posts demonstrated intermediate fracture resistance values. e improved mechanical behavior of customized composite posts in comparison to fiber posts can be attributed to close adaptation of posts to canal wall as stated by Macedo et al [34]. e lower fracture resistance of Customized Composite Post (CCP) as compared to Cast metal post (CMP) could be due to difference in the modulus of elasticity of composite and resin cement as well as the presence of an additional interfaces for bonding between the post-composite and composite-resin cement
Summary
Restoration of immature teeth with open apices and thin dentinal walls with conventional post systems remains a challenge. e purpose of this study was to evaluate the fracture resistance of simulated immature teeth restored with different intraradicular posts and assess their stress distribution pattern using 3D Finite Element Analysis (FEA). Teeth restored with cast metal posts and cores exhibited maximum fracture resistance followed by the customized composite posts, the fiber posts, and the control group. Loss of vitality of a developing tooth due to trauma or extensive caries results in thin, divergent dentinal walls of root canal with open apex Such teeth are weak in cervical areas of root, thereby increasing fracture susceptibility even to normal functional stresses [2]. Advocated method of single step apexification using MTA provides several advantages, which include shorter treatment time, excellent biocompatibility, and good apical seal [5]. Revascularization is yet another alternative for management of immature teeth. There is little evidence providing established success rates and predictability of the outcome, despite promising results shown by several case reports [7]
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