Effect of fibre-reinforced composite as a post-obturation restorative material on fracture resistance of endodontically treated teeth: A systematic review

Effect of Fiber-Reinforced Composite Placement Site on Fracture Resistance of Premolar Teeth: An in vitro Study

Background

This study aimed to investigate the fracture behavior of upper premolars with deep MOD cavities that were restored with Ribbond resin-reinforced fibers (FRCs) placed in different orientations.

Methods

A total of 54 extracted maxillary premolars were randomly divided into nine groups. The experimental groups underwent MOD cavity preparation with or without root canal treatment, followed by FRCs placed in the pulpal floor, proximal walls, or both. Fracture resistance was tested using an Instron Machine. The samples were visually inspected to analyze the fracture mode.

Results

The highest fracture resistance was observed in intact teeth (1299.98 ± 284.66 MPa). Placing Ribbond fibers in the pulpal floor (1155.86 ± 244.21 MPa) or the proximal walls (1077.56 ± 260.60 MPa) significantly improved fracture resistance (p= <0.05), compared to cavities restored with only resin composite (804.58 ± 93.34 MPa). However, placing Ribbond fibers in both the pulpal and proximal walls did not enhance fracture resistance. In the MOD-RCT groups, fracture resistance was improved only when Ribbond fibers were placed in the pulpal floor and the proximal walls. Fracture mode analysis revealed a combined fracture in most of the groups.

Conclusion

This study concluded that using FRCs significantly improved the fracture resistance of MOD cavities in premolars and revealed that the placement site could be a determinant factor.

From Crisis to Victory: Rescuing Root Canal Treatment With Bioactive Material in a Nail-Biting Case of Furcal Perforation

This case report illustrates the successful treatment of an iatrogenic furcal perforation using mineral trioxide aggregate (MTA) and its reinforcement with fiber-reinforced composites (FRCs). Endodontic perforations, particularly in the furcal area, present unique challenges that demand effective management strategies. MTA, known for its multifaceted properties including osteoinductive activity and sealing capabilities, has emerged as the gold standard material for perforation repair. This case report demonstrates the application of MTA in repairing the perforation site following thorough cleaning and shaping of the root canals. Furthermore, the use of FRCs, specifically glass fiber-reinforced composite (GFRC), is introduced to reinforce the repaired site, enhancing its mechanical properties and long-term stability. The discussion emphasizes the importance of selecting appropriate materials for endodontic perforation repair and highlights the advantages of FRCs in preventing structural failures. Future directions suggest further research to refine FRC formulations and standardize clinical protocols to maximize treatment outcomes. This case report contributes valuable insights to the advancement of endodontic therapy, showcasing the combined benefits of MTA and FRCs in achieving favorable treatment outcomes for iatrogenic furcal perforations.

Stress Analysis on Mesiolingual Cavity of Endodontically Treated Molar Restored Using Bidirectional Fiber-Reinforced Composite (Wallpapering Technique)

Introduction

Endodontically treated teeth (ETT) undergo extensive structure change and experience high stress during biomechanical function. Stress distribution is influenced by the restoration material and the type of bond between material and tooth structure. The selection of materials that can distribute stress will affect the resistance and retention of ETT to mastication forces, thus biomechanical functions were achieved. Composite has mechanical properties similar to dentin, it can transmit and distribute stresses throughout the tooth surface. The disadvantage of composites in large cavities is their lack of toughness. The addition of fiber to composites can increase their toughness.

Purpose

This research is to determine the stress distribution of a fiber-reinforced composite made of polyethylene and e-glass on the mesiolingual cavity of ETT.

Materials and Methods

A three-dimensional model of the mandibular molar was prepared for cavity preparation and the formation of restorations using SolidWorks 2021. The models were analyzed with Abaqus 2020 to determine stress concentrations after given vertical and oblique loading.

Results

The maximum and minimum principal stress data were obtained to assess material resistance and interfacial damage criterion. Polyethylene fiber shows a more homogeneous stress distribution because the modulus of elasticity is close to the dentin and has a thickness that can reduce the volume of the composite. The E-glass shows the stress concentration on the circumferential fiber and cavity floor.

Conclusion

The stress distribution of fiber-reinforced composite on the buccolingual cavity of ETT using the finite element method did not show structural failure in the polyethylene group because the maximum and minimum principal stresses were lower than the strength of the material. Interfacial bond failure occurs at the enamel portion. The maximum and minimum principal values of e-glass indicate structural failure in the circumferential fiber and the base fiber because the stress exceeds the strength of the material. Interfacial bond failure occurred on the circumferential and the cavity floor.

Short fiber-reinforced composite resins as post-and-core materials for endodontically treated teeth: A systematic review and meta-analysis of in vitro studies

STATEMENT OF PROBLEM

As the use of traditional posts has been associated with complications and failure outcomes, the introduction of novel materials and minimally invasive dentistry has shifted toward the use of composite resin post-and-core restorations for endodontically treated teeth. As a further process, to improve stress absorption environment in restored teeth, the invention of short fiber-reinforced composite resins (SFRCs) as post-and-core restorations has recently emerged. However, evidence regarding its performance is still scarce, and a synthesis of existing data is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to assess the performance of SFRC post-and-core restorations, regarding fracture resistance and failure mode and considering both cyclic and static loading.

MATERIAL AND METHODS

An electronic search in 5 databases was conducted up to August 2022, and the protocol of the study was registered a priori. The search terms included "fiber reinforced composite," "core build-up," and "post." Studies were considered if they compared SFRC restorations with other types of conventional posts and teeth restored using bulk fill composite resin. The internal validity of the studies was assessed by using a custom-made risk of bias tool.

RESULTS

A total of 1271 records were identified, of which 13 were considered for full-text assessment. Eight were ultimately included, all being in vitro studies, and 7 of them were deemed eligible for quantitative syntheses. The results varied considerably across studies with divergent fracture resistance values and percentages of catastrophic failure being reported. Standard depth (6 mm) SFRCs presented fewer repetitions until fracture on average, compared with the individually made FRCs (3 studies: mean difference (MD): -4062; 95% CI: -6148, -1975; P<.001) under cyclic loading. Under static loading, SFRCs (standard depth) presented a nearly 300 N lower fracture force compared with that of intact teeth, (3 studies: MD: -297; 95%CI: -378, -216; P<.001).

CONCLUSIONS

Evidence on the laboratory fracture and failure performance of SFRCs is limited, and future studies should incorporate more standardized experimental conditions, as well as SFRCs with limited sacrifice of tooth substrate within the root canal of endodontically treated teeth.

The Restored Premolars Biomechanical Behavior: FEM and Experimental Moiré Analyses

This study applied the finite element method (FEM) and the moiré strip projection method to evaluate the biomechanical behavior of healthy and endodontic-treated premolar teeth. The finite element method and the moiré strip projection method were applied to evaluate the influence of restored materials in association with cervical lesions and were considered as strain estimates for a tooth sample with 21 units, under loads of 25, 50, 75, and 100 N, frontal and oblique applied. The focused cases were: tooth H healthy; tooth A-MOD amalgam; tooth AL-MOD amalgam + lesion; tooth ALR-MOD amalgam + injury restored; tooth R-MOD resin; tooth RL-MOD resin + lesion; tooth RLR-MOD resin + injury restored. The results obtained by FEM simulation can be considered perfectly validated by the results presented by the experimental moiré projection analysis, demonstrating that the FEM numerical analysis can be used to evaluate the biomechanical behavior of healthy and endodontically treated teeth. Developing an alternative protocol to generate FEM three-dimensional models will lead to a ready and inexpensive tool since there is no need for costly equipment for tooth extraction prognosis.