The influence of elastic moduli of core materials on shear stress distributions at the adhesive interface in resin built-up teeth

Abstract

This study aimed to investigate shear stress distributions in resin built-up teeth using resin composites of varying elastic moduli (E), with or without fiber posts. Three-dimensional mathematical models of a root-filled mandibular premolar tooth were constructed. Resin post and cores were built-up with resin composites of three different E: 12,000, 18,000 and 24,000 MPa, with or without fiber posts. Finite element linear analysis was performed to calculate shear stress distributions at bonding interface between resin core and dentin. Regardless of fiber post insertion, the shear stress on the cervical surface of resin core decreased as the E of resin composites increased. Insertion of fiber posts increased the shear stress on the post surface of resin core, with increases in the E of resin composites. In conclusion, using resin core materials with higher E decreased the shear stress at cervical interface between resin core and dentin regardless of fiber post insertion.

Stress distribution in tooth resin core build-ups with different post-end positions in alveolar bone level under two kinds of load directions

“…3-b), regardless of incorporation of a fiber post. These results are in agreement with previous studies 8,20,21,27,35) . On the other hand, loading from the lingual side (B direction) caused a greater magnitude of maximum equivalent stress in root dentin than that from a buccal side (A direction) (Fig.…”

“…Concentrations of shear stress cause the debonding of post and cores from root dentin and increase the fracture risk of root and/ or resin core materials 17,21) . The maximum shear stress has been reported to be located at the mesiodistal edge of the cervical surface between root dentin and the resin core 27) . The post-end positions in the root in the alveolar bone might affect the shear stress distribution in resin core build-ups under different load directions.…”

Microtomographic Analysis of Resin Composite Core Material Porosity

“…Porosity has been suggested to degrade resin composite materials’ mechanical properties via many mechanisms 13,14,27,33‐41 . Depending on the remaining tooth structure and preparation of the ferrule design, a resin composite core material plays a vital role in the restoration of root‐filled teeth managing the applied functional forces applied to the remaining tooth structure 42,45,46,55‐59,65 . This work investigated the porosity in 10 currently‐marketed resin composite core materials using a nondestructive microCT methodology.…”

“…Overall, porosity's role possibly contributing to future failure of many dental materials may be not considered by many clinicians 42‐44 . In the rehabilitation of root‐filled teeth there may be a predominant and correct research focus on post arrangement and selection as well as ferrule preparation design 45‐68 . Nonetheless, resin composite core material mechanical properties are an important but sometimes overlooked factor in the successful restoration of root filled teeth, as the resin composite core material is an integral part of the complex tooth‐restoration multicomponent system that distributes multi‐axial and non‐uniform forces applied to the full coverage restoration to the remaining tooth structure 42 .…”

“…However, when substantial coronal tooth structure disallows adequate preparation ferrule, finite element analysis (FEA) studies indicate that applied forces concentrate in the preparation cervical area 42 . In these situations resin composite core material's properties become more significant in transferring/mitigating functional forces to the radicular structures 42,45,46,49,52,55‐59,65 . Namely, studies suggest that the resin composite core modulus is an important factor that influences fatigue force concentration to cervical resin‐dentin adhesive interfaces, 58,59 as well as possibly compensating for inadequate and/or short intracanal posts 60‐64 .…”