The effect of glass and polyethylene fiber reinforcement on flexural strength of provisional restorative resins: an in vitro study

Biomimetic approach to strengthen the incisal fracture composite build-up: an in vitro study

OBJECTIVE

Incisal composite build-up shows a high failure susceptibility. The incorporation of fiber-reinforced composite (FRC) during composite restoration could improve its strength. Hence the study was planned to compare the effect of various positions of FRC on the strength of composite resin incisal build-ups.

METHODS

In maxillary incisors (n = 90), 3 mm of the incisal edge was cut and teeth were categorized into three groups based on the location and number of fibers used during incisal composite build-up - Group I: composite resin; Group II: composite resin and a single fiber palatally and Group III: composite resin along with two fibers palatally.

RESULTS

The data showed that group II had the maximum load-bearing values followed by group I and group III.

CONCLUSION

Within the confines of our study, it can be concluded that the addition of FRC to the conventional incisal composite build-up increased the overall strength restoration. Such composite restoration reinforced with a single fiber on the palatal side showed the highest load-bearing capacity compared to two fibers reinforced and unreinforced composites. The common mode of failure in group I was in composite resin, in two fibers reinforced at fibers-composite junction, and in one fiber reinforced composite was in the remaining part of the tooth.

Restoration of a Vital Tooth With Extensive Crown Destruction Using Glass Fiber and Polyethylene Fiber-reinforced Composite Resin: A Clinical Case

Conservative restorative dentistry has been evolving in the last 25 years, focusing mainly on the development of direct restorative materials. Resin-based composites remain an excellent conservative alternative for restoration of teeth with extensive caries lesions. Over time, several strategies have been proposed to improve the mechanical properties of these composites so that they can adequately withstand masticatory forces. Glass fiber-reinforced resin-based composites and their use in situations where there is great loss of tooth structure have gained popularity due to their favorable mechanical properties. Combined techniques with polyethylene fibers can further enhance their clinical performance. This study presents a brief review of their most important qualities and potential use in direct restorative procedures. In addition, a clinical case is described where a vital tooth with extensive coronal destruction was restored using polyethylene fibers embedded in glass fiber-reinforced flowable resin under resin-based composite. The reinforcement of both the remaining tooth structure and the restoration with fibers is a valid treatment option since the network structure formed by the fiber reinforcement can increase the longevity of the direct composite restorations. There are few reports in the literature describing the use of a combined technique using polyethylene fibers embedded in glass fiber-reinforced flowable resin under resin-based composite. Thus, clinical follow-up of this case is required.

Fracture Resistance of Endodontically Treated Maxillary Premolar Teeth Restored with Wallpapering Technique: A Comparative In Vitro Study

Objectives

This in vitro study aimed to evaluate and compare the fracture resistance and mode of failure of endodontically treated maxillary premolar teeth restored with different direct composite restorative techniques.

Materials and Methods

Forty freshly extracted maxillary premolar teeth with comparable sizes were used in this in vitro study. Each tooth received mesio-occluso-distal cavity preparation (3 mm width and 6 mm depth) followed by endodontic treatment. Canals were instrumented with RACE EVO rotary files (FKG, Dentaire, Switzerland) up to MAF 25/.06. Canals were obturated using a single cone technique, then the teeth were divided arbitrarily into five groups (n = 8): Group A: direct composite resin only using a centripetal technique, Group B: direct composite resin with glass fiber post, Group C: direct composite resin with short fiber-reinforced composite (everX Flow), Group D: direct composite resin with leno wave ultra high molecular weight polyethylene (LWUHMWPE) fibers placed on cavity floor, and Group E: direct composite resin with LWUHMWPE fibers placed circumferentially around the cavity walls (wallpapering technique). The teeth were then stored in distilled water at 37°C for 24 hr. The fracture resistance of each sample was measured using a universal testing machine in Newton (N). The data were analyzed using one-way analysis of variance (ANOVA) and the Bonferroni test with a significance level of 0.05.

Results

Group E recorded the maximum mean of fracture load (2,139.375 N), while Group A recorded the minimum mean of fracture load (689.6250 N). The one-way ANOVA test revealed a significant difference between the groups. The Bonferroni test showed a significant difference between each two groups, with the exception of those between Groups B and C and between Groups D and E, where there were no statistically significant differences (p > 0.05).

Conclusion

Restoration of endodontically treated teeth using the wallpapering technique recorded the highest mean of fracture resistance with a repairable mode of fracture.

Evaluation of Fracture Strength of Fiber-Reinforced Direct Composite Resin Restorations: An In Vitro Study

This in vitro study aimed to compare the fracture strength of direct non-reinforced class II composite resin restorations and polyethylene fiber-reinforced restorations, and also to investigate the influence of the locations of polyethylene fibers within the cavity on the fracture strength. Sixty freshly extracted human teeth were disinfected and prepared (class II cavity design). The teeth were assigned randomly into four groups (n = 13). Group I (control) was restored with nano-hybrid composite resin. The other three experimental groups were restored with the same composite resin material reinforced by polyethylene fibers (Ribbond) at different locations. Fibers were placed either on the axial wall (Group II), on the gingival floor (Group III), or on the axial wall and pulpal/gingival floor (Group IV) of the proximal cavity. All the teeth were subjected to thermocycling to simulate the oral environment. The fracture strength was measured using a universal testing machine. Group IV had the highest mean fracture strength at maximum load (148.74 MPa), followed by Group II (140.73 MPa), Group III (136.34 MPa), and Group I (130.08 MPa), with a statistically significant difference from the control group (p = 0.008) but not between groups II and III.

Glass Fibers Reinforced Concrete: Overview on Mechanical, Durability and Microstructure Analysis

Prior studies in the literature show promising results regarding the improvements in strength and durability of concrete upon incorporation of glass fibers into concrete formulations. However, the knowledge regarding glass fiber usage in concrete is scattered. Moreover, this makes it challenging to understand the behavior of glass fiber-reinforced concrete. Therefore, a detailed review is required on glass fiber-reinforced concrete. This paper provides a compressive analysis of glass fiber-reinforced composites. All-important properties of concrete such as flowability, compressive, flexural, tensile strength and modulus of elasticity were presented in this review article. Furthermore, durability aspects such as chloride ion penetration, water absorption, ultrasonic pulse velocity (UPV) and acid resistance were also considered. Finally, the bond strength of the fiber and cement paste was examined via scanning electron microscopy. Results indicate that glass fibers improved concrete’s strength and durability but decreased the concrete’s flowability. Higher glass fiber doses slightly decreased the mechanical performance of concrete due to lack of workability. The typical optimum dose is recommended at 2.0%. However, a higher dose of plasticizer was recommended for a higher dose of glass fiber (beyond 2.0%). The review also identifies research gaps that should be addressed in future studies.

Physicochemical properties of discontinuous S2-glass fiber reinforced resin composite

The objective of this study was to investigate several physicochemical properties of an experimental discontinuous S2-glass fiber-reinforced resin composite. The experimental composite was prepared by mixing 10 wt% of discontinuous S2-glass fibers with 27.5 wt% of resin matrix and 62.5 wt% of particulate fillers. Flexural strength (FS) and modulus (FM), fracture toughness (FT), work of fracture (WOF), double bond conversion (DC), Vickers hardness, volume shrinkage (VS) and fiber length distribution were determined. These were compared with two commercial resin composites. The experimental composite showed the highest FS, WOF and FT compared with two control composites. The DC of the experimental composite was comparable with controls. No significant difference was observed in VS between the three tested composites. The use of discontinuous glass fiber fillers with polymer matrix and particulate fillers yielded improved physical properties and substantial improvement was associated with the use of S2-glass fiber.

The Effect of Polymerization Methods and Fiber Types on the Mechanical Behavior of Fiber-Reinforced Resin-Based Composites

PURPOSE

Glass fibers were introduced to increase the fracture resistance of resin-based composites restorations; however, the poor polymerization between fibers and resin-based composite were sometimes noted and can cause debonding and failure. The purpose of this study was to investigate the effects of different polymerization methods as well as fiber types on the mechanical behavior of fiber-reinforced resin-based composites.

MATERIALS AND METHODS

Seventy-five specimens were fabricated and divided into one control group and four experimental groups (n = 15), according to the type of glass fiber (strip or mesh) and polymerization methods (one- or two-step). A 0.2-mm-thick fiber layer was fabricated with different polymerization methods, on top of which a 1.8 mm resin-based composite layer was added to make a bar-shape specimen, followed by a final polymerization. Specimens were tested for flexural strength and flexural modulus. The failure modes of specimens were observed by scanning electron microscopy.

RESULTS

The fiber types showed significant effect on the flexural strength of test specimens (F = 469.48, p < 0.05), but the polymerization methods had no significant effect (F = 0.05, p = 0.82). The interaction between these two variables was not significant (F = 1.73, p = 0.19). In addition, both fiber type (F = 9.71, p < 0.05) and polymerization method (F = 12.17, p < 0.05) affected the flexural modulus of test specimens; however, the interaction between these two variables was not significant (F = 0.40, p = 0.53).

CONCLUSIONS

The strip fibers showed better mechanical behavior than mesh fibers and were suggested for resin-based composites restorations reinforcement; however, different polymerization methods did not have a significant effect on the strength and failure mode of fiber-reinforced resin-based composites.