Stress Generated by Customized Glass Fiber Posts and Other Types by Photoelastic Analysis

Abstract

Endodontic posts are necessary to provide adequate retention and support when no sufficient remaining structure is available to retain the core. There are different materials and techniques to construct post-and-core, but there is no consensus about which one promotes better stress distribution on the remaining tooth structure. This study aimed to quantify and evaluate the distribution of stress in the root produced by customized glass fiber posts compared to different endodontic posts. Twenty-five simulated roots from photoelastic resin were made and divided into 5 groups: CPC, cast post-and-core; SP, screw post; CF, carbon fiber post; GF, glass fiber post; and CGF, customized glass fiber post. After cementing CPC and SP posts with zinc phosphate cement, and CF, GF and CGF posts with resin cement, resin cores were made for groups 2-5. Specimens were evaluated with vertical or 45° oblique loading. To analyze the fringes, the root was divided into 6 parts: palatal cervical, palatal middle, palatal apical, vestibular cervical, vestibular middle, and vestibular apical. The formed fringes were photographed and quantified. Data were recorded and subjected to two-way ANOVA and Tukey's test (5%). SP (1.95±0.60) showed higher stress (p<0.05) compared to the others (CPC-0.52±0.74; CF-0.50±0.75, GF-0.23±0.48 and CGF-0.45±0.83). All posts showed high stress in apical third (CPC-1.40±0.65; SP-2.30±0.44, CF-1.80±0.45, GF-1.20±0.45, CGF-1.70±1.03) Low stress was found in cervical third (CPC-0.20±0.45; CF-0.00±0.00, GF-0.00±0.00, CGF-0.00±0.00), except by SP (1.90±0.65), which showed statistical difference (p<0.05). Customized post showed high stress concentration at the root and conventional glass fiber posts showed more favorable biomechanical behavior.

Evaluation of the Effect of Rotary Systems on Stresses in a New Testing Model Using a 3-Dimensional Printed Simulated Resin Root with an Oval-shaped Canal: A Finite Element Analysis Study

“…High stresses occurred when the models were loaded at an angle (Figs. 1-3), confirming the previously demonstrated facts that the pattern of stress distribution is affected by loading direction (24) and higher stresses generally occurred in the teeth when loaded at an angle (23). The results also indicated that preparations with different rotary systems have different effects on stress distribution within the photopolymerized resin roots with oval-shaped canals.…”

“…Von Mises stresses (the global [X, Y, and Z directional axes] combination of the absolute values squared of all stresses) were used for evaluation (18). Von Mises stresses are widely used as a failure criterion that shows energy transmission in a structure, and if there is a higher concentration of energy, the maximum principal stress discriminates the tensile and compressive stress fields (23).…”

Effect of Glass Fiber Post Adaptation on Push-Out Bond Strength to Root Dentin

“…Some techniques have been proposed for cementing fiber glass posts to reduce the volume of cement and consequently achieve better adaption between the post and root canal. Some studies have shown that thick cement layers decrease the bond strength (11)(12), since a greater volume of cement leads to greater volume shrinkage, generating a higher shrinkage stress at the adhesive interface and causing a greater formation of gaps inside the root canal (7,9,(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12).…”

In vitro evaluation of the shear bond strength between fiber posts and methacrylate or silorane based composite resins

“…In that matter, different surface treatments have been described, such as silanization and application of an adhesive system [3,4,[28][29][30][31][32], to ensure the bond between the resin-based materials and FP. However, for the customized-post technique there are not enough studies to determine if the adhesive use in the preparation of FP surface is actually required [33,34]. Therefore, the current study evaluated the bond strength of silorane-based, a bulkfill methacrylate-based and a conventional methacrylate-based CR to a fiber post, with and without the use of adhesive systems.…”