Effect of fiber orientation and type of restorative material on fracture strength of the tooth

Properties of model E-glass fiber composites with varying matrix monomer ratios

OBJECTIVE

To evaluate properties of fiber-reinforced-composites (FRC) containing Bis-EMA/UDMA monomers but identical dispersed phase (60% wt BaSi glass power +10% wt E-glass fibre).

METHODS

A control (Group A), monomer mixture comprising 60% Bis-GMA, 30% TEGDMA, and 10% PMMA (typical FRC monomers) was used. The following monomer mass fractions were mixed: 50% bis-GMA plus 50% of different ratios of Bis-EMA+UDMA to produce consistent formulations (Groups B-E) of workable viscosities was also studied. Flexural strength (FS), fracture toughness (KIC), water sorption (SP), solubility (SL) and hygroscopic expansion (HE) were measured. FS and KIC specimens were stored for 1, 7 d, and 30 d in water at 37 °C. SP/SL specimens were water-immersed for 168d, weighed at intervals, then dried for 84 d at 37 °C. To analyze differences in FS, and KIC, a two-way ANOVA and Tukey post-hoc tests (α = 0.05) were conducted. For SP/SL, and HE, one-way ANOVA with subsequent Tukey post-hoc tests (α = 0.05) were utilized.

RESULTS

FS and KIC for groups A, D, E decreased progressively after 1 d. Groups B and C (highest amounts of Bis-EMA) did not decrease significantly. The modified matrix composites performed significantly better than the control group for SP and HE. The control group outperformed the experimental composites only for SL with up to 250% higher SL for group E (6.9 μg/mm) but still below the maximum permissible threshold of 7.5 μg/mm.

SIGNIFICANCE

EXPERIMENTAL: composites with highest amounts of Bis-EMA showed improved hydrolytic stability and overall enhancement in several clinically-relevant properties. This makes them potential candidates for alternative matrices to a semi-interpenetrating network in fiber-reinforced composites.

Effect of polyethylene fiber orientation on fracture resistance of endodontically treated premolars

STATEMENT OF PROBLEM

Polyethylene fibers have been reported to improve the fracture resistance of endodontically treated teeth, but their optimal orientation is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the effects of different fiber positions and orientations on the fracture resistance of endodontically treated premolar teeth.

MATERIAL AND METHODS

One hundred endodontically treated maxillary premolars were divided into 2 groups according to the cavity design, mesio-occluso-distal and occluso-buccal, and each group was divided into 5 subgroups (n=10) according to the polyethylene fiber orientation on the pulpal floor: unidirectional horizontal (from mesial to distal), unidirectional vertical (from buccal to palatal), bidirectional (buccopalatal and mesiodistal), circular (around the walls), and without fibers (control group). The cavities were restored with fiber-reinforced composite resin and conventional composite resin. All the teeth were fractured with a universal testing machine and analyzed as catastrophic failure or reparable failure. A 1-way ANOVA was used to compare fracture strength values (α=.05).

RESULTS

The tested groups with different fiber orientations showed significantly higher fracture load than the control group (P<.05). No statistically significant difference was observed among the fiber orientations (P>.05). Most of the favorable fractures were occlusal to the cemento-enamel junction, and adhesive failure were seen in the mesio-occluso-distal and occluso-buccal cavities. The highest percentage of unfavorable fractures and mixed failures was observed in the control group.

CONCLUSIONS

The fiber orientation pattern in the mesio-occluso-distal and occluso-buccal cavities did not differ significantly in the fracture resistance of endodontically treated maxillary premolar teeth.

Effect of fiber orientation and placement on fracture resistance of large class II mesio-occluso-distal cavities in maxillary premolars: An in vitro study

Background and Aim:

To analyze the outcome of fiber placement and orientation over fracture resistance in wide Class II (Mesio-occluso-distal [MOD]) cavities prepared on maxillary premolars.

Materials and Methods:

After selection of 120 extracted human maxillary premolars, Class II (MOD) cavities were prepared maintaining uniform dimensions and samples were divided into six groups randomly (n = 20 each): Group I, G-aenial posterior; Group II, G-aenial posterior + Horizontal Ribbond placement on gingival and pulpal floor; Group III, G-aenial posterior + Horizontal Ribbond placement only on pulpal floor; Group IV, G-aenial posterior + vertical Ribbond placement on gingival and pulpal floor; Group V, G-aenial posterior + Ribbond chips; Group VI, Ever-X posterior. After restorations and completion of thermocycling process, universal testing machine measured the fracture resistance of all samples. Fracture modes were inspected under stereomicroscope. Analyzation of data was performed using one-way ANOVA and Tukey test at significance levels of P < 0.05.

Results:

Fiber placement significantly increased fracture resistance. The highest fracture resistance was shown by Group 2 (1288.8 N) followed by Group 3 (976 N), group 4 (942.3 N), Group 5 (876.3 N), and Group 6 (833 N). Group 1 (No Fiber group) showed the least fracture resistance of 588.41 N. Repairable fractures were seen highest with Group 2 (80%) followed by Group 6 (70%) and least in Group 1 (30%).

Conclusions:

Horizontal orientation of polyethylene fiber on both pulpal and gingival floor of MOD cavities gives the highest fracture resistance in maxillary premolars and repairable mode of fracture.

Current trend of restoration of endodontically treated teeth with extensive subgingival caries: A case series

Endodontically treated teeth (ETT) are structurally and esthetically compromised. Conventionally, after endodontic therapy, the tooth is restored with full-coverage crowns to improve their fracture resistance and ensure their long-term success rate. However, the tooth preparation required for these restorations can result in the significant loss of enamel and dentin. The periodontal health will be affected if the margin of prosthesis is extended subgingival. Restoring ETT using minimally invasive methods is an effective way to preserve the remaining tooth structure. This case series show cases restoration of four endodontically treated mandibular first molars with extensive subgingival caries restored with short fiber-reinforced composite resin (everX Posterior, GC Europe N.V. Interleuvenlaan, Leuven), with 2-year follow-up.

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

Background

Fracture resistance of endodontically treated tooth is affected due to large cavity designs and access cavities and an appropriate material capable to resist fracture plays an important role. This review aims to evaluate the effect of fibre-reinforced composite (FRC) as a post-obturation material on fracture resistance of endodontically treated teeth.

Objectives

To systematically gather and evaluate the fracture resistance of fibre-reinforced composite as a post-obturation restorative material in endodontically treated teeth.

Data Sources

A systematic search was conducted using PubMed, Ebsco Host, Scopus, Google Scholar, Hinari and manual search library resources from 1st Jan 2000 to 30th November 2019 to identify appropriate studies.

Result

A total of 157 articles were examined out of which 55 articles were selected after reading the title. After removing the duplicates, 27 articles were screened for abstract and 1 article was eliminated as it did not meet the eligibility criteria. A thorough reading of the full text of the remaining 26 selected articles was assessed for eligibility. Amongst these, 1 article was then excluded from the study as the full text was not accessible. Lastly, 25 articles were included in the study.

Conclusion

FRC as a core material increases fracture resistance of endodontically treated teeth but they do not have the fracture resistance similar to the intact tooth. Both polyethylene and short fibre-reinforced composites showed greater fracture resistance when compared to glass FRC and restoration without reinforcement. Also, the fracture resistance increases if restored with FRC along with retention slots and are placed on the occlusal third surfaces of cavities. Also, favourable fractures were most commonly seen and it usually occurred at the level of enamel and dentin and adhesive fractures were seen.

Comparison of fiber-reinforced composite and nanohybrid resin impregnated with glass fibers as postendodontic restoration in molars – A clinical study

Background:

Aim:

Materials and Methods:

Statistical Analysis:

Results:

Conclusion:

Effect of Accelerated Aging on Color Change of Direct and Indirect Fiber-Reinforced Composite Restorations

OBJECTIVES

The aim of this study was to assess the effect of artificial accelerated aging (AAA) on color change of direct and indirect fiber-reinforced composite (FRC) restorations.

MATERIALS AND METHODS

Direct (Z250) and indirect (Gradia) composite resins were reinforced with glass (GF) and polyethylene fibers (PF) based on the manufacturers' instructions. Forty samples were fabricated and divided into eight groups (n=5). Four groups served as experimental groups and the remaining four served as controls. Color change (ΔE) and color parameters (ΔL*, Δa*, Δb*) were read at baseline and after AAA based on the CIELAB system. Three-way ANOVA and Tukey's test were used for statistical analysis.

RESULTS

Significant differences were found in ΔE, ΔL*, Δa* and Δb* among the groups after AAA (P<0.05). Most of the studied samples demonstrated an increase in lightness and a red-yellow shift after AAA.

CONCLUSIONS

The obtained ΔE values were unacceptable after AAA (ΔE≥ 3.3). All indirect samples showed a green-blue shift with a reduction in lightness except for Gradia/PF+ NuliteF.