Clinical Performance of Short Fibre-reinforced Glass Ionomer Cement Restorations in Cervical Carious Lesions: 12-Month Randomized Clinical Trial.

The aim was to assess the clinical performance of experimental short fiber-reinforced glass-ionomer cement (FR-GIC) in the treatment of cervical caries lesions. A total of 45 patients were randomly enrolled in this trial according to the split-mouth design. The FR-GIC was prepared by adding short glass fibers at a mass ratio of 20% into the powder portion of Fuji II LC. The cervical lesions in the intervention group were restored with FR-GIC, while unmodified Fuji II LC was applied as the control. Clinical evaluation was performed by two blinded operators at baseline, at 6, and 12 months using modified USPHS criteria. The data were analyzed using Friedman's test, followed by the Nemenyi post hoc test with a significance level of α = 0.05. After 1 year, all restorations were fully retained. There was no statistically significant difference (p⟩0.05) between the two materials based on the evaluated criteria. Both groups had 4 (10%) cases with Bravo scores for cavos-surface marginal discoloration. Regarding marginal integrity, Bravo scores were observed in 5 (12.5%) cases in the intervention group and 4 (10%) cases in the control group. Both materials in the treatment of cervical caries lesions demonstrated satisfactory clinical outcome throughout the 12-month follow-up.

Fracture behavior of short fiber-reinforced CAD/CAM inlay restorations after cyclic fatigue aging.

The aim of this study was to assess the fracture behavior of molar teeth restored with MOD inlays made of experimental short fiber-reinforced CAD/CAM composite block (SFRC CAD) before and after cyclic fatigue aging. Standardized MOD cavities were prepared on 60 intact mandibular molars. Three groups of CAD/CAM made inlay restorations (Cerasmart 270, Enamic, and SFRC CAD) were fabricated (n = 20/group). All restorations were luted with self-adhesive dual-cure resin cement (G-Cem One). Half of restored teeth per each group (n = 10) were quasi-statically loaded until fracture without aging. The other half underwent cyclic fatigue aging for 500,000 cycles (Fmax = 150 N) before being loaded quasi-statically until fracture. Then, the fracture type was visually inspected. The microstructure and elemental content of CAD/CAM materials were assessed using SEM and EDS. Two-way analysis of variance (ANOVA) was used to statistically examine the data, and it was followed by the Tukey HSD test (α = 0.05). ANOVA demonstrated that both material type and aging had a significant effect (p < 0.05) on the load-bearing capacity values of the restorations. Teeth restored with SFRC CAD showed significantly the highest (p < 0.05) load-bearing capacity (2535 ± 830 N) after fatigue aging among all groups. SEM images showed the ability of short fibers in SFRC CAD composite to redirect and hinder crack propagation. With regard to fracture mode, Enamic group revealed 85% of catastrophic failure (vs. 45% and 10% for Cerasmart 270 and SFRC CAD, respectively). Large MOD cavities on molar teeth were most favorably restored with SFRC CAD inlays, yielding the highest load-bearing capacity and more restorable failures.

Evaluation of fracture behavior in short fiber-reinforced direct and indirect overlay restorations.

OBJECTIVES: The aim was to assess how incorporating a short-fiber composite (SFC) core would affect the fracture behavior of direct and indirect overlays. Furthermore, to examine the relationship between the thickness ratio of SFC core to particulate-filled composite (PFC) veneering and the fracture-behavior of bilayered-structured restorations. MATERIALS AND METHODS: A total of 120 molars were used to create MOD cavities, with palatal cusps removed. Four different groups of direct overlays were then made (n = 15/group), all of which featured a SFC core (everX Flow) with varying thicknesses (0, 1, 4, and 5 mm), as well as a surface layer of PFC (G-aenial Posterior), with the overall thickness of the bilayered-structured restoration set at 5 mm. Additionally, four groups of CAD/CAM restorations were created (Cerasmart 270 and Initial LiSi Block), with or without 2 mm of SFC core reinforcement. Following the fabrication of these restorations, cyclic fatigue aging was carried out for a total of 500,000 cycles, with an applied maximum load (Fmax) of 150 N. Subsequently, each restoration underwent quasi-static loading until fracture. The fracture mode was subsequently evaluated using optical microscopy and SEM. RESULTS: There were no statistically significant differences (p > 0.05) observed in the fracture resistance of indirect overlays reinforced with a 2-mm SFC core compared to those made solely from restorative materials. Direct overlays constructed using plain SFC or with a 4-mm layer thickness of SFC core exhibited significantly higher fracture resistance values (2674 ± 465 and 2537 ± 561 N) (p < 0.05) when compared to all other groups tested, according to the statistical analysis ANOVA. CONCLUSIONS: The most effective method for restoring large MOD cavities was found to be direct restoration using SFC either alone or as a bulk core in combination with PFC composite. CLINICAL RELEVANCE: The use of SFC as bulk reinforcing base will significantly improve the loading performance of directly layered restorations.

Can Specular Gloss Measurements Predict the Effectiveness of Finishing/Polishing Protocols in Dental Polymers? A Systematic Review and Linear Mixed-effects Prediction Model.

PURPOSE: The current gold standard measure to assess polishing efficacy is surface roughness (SR) assessed in laboratory research. Specular gloss (SG) has been negatively correlated to SR, which raises the following question: Can SG be used to accurately determine the effectiveness of a finishing/polishing procedure in direct resin composites? METHODS: A systematic approach and search strategy, following Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, was developed and conducted in five electronic databases: PubMed/Medline, Scopus, Web of Science, EMBASE (Ovid), and SciELO/LILACS to identify laboratory studies that assessed SR and SG, simultaneously, of resin composites, without date or language restriction. Risk of bias assessment was carried out by two reviewers, independently. From the extracted quantitative data of SG/SR, regression analyses were performed, and a linear mixed-effects prediction model was derived using the nimble package in R (v4.0.3). RESULTS: A total of 928 potential studies were found, out of which, 13 were eligible after criterion screening. Experimental groups featured 31 resin composites of six different filler types, with the most common being microhybrids followed by nanohybrids. More than half of the studies initially reported a linear correlation between SR and SG, which ranged from r2 = 0.34-0.96. Taking into account the regression analysis and prediction model posteriorly performed, the corresponding SG threshold for 0.2 µm is estimated to be >55 GU. Most of the evidence was classified as moderate or high risk of bias. CONCLUSION: SG is universally correlated to SR in polymers, and a reference value of >55 GU is proposed, above which samples are considered well polished.

Effect of interfacial surface treatment on bond strength of particulate-filled composite to short fiber-reinforced composite.

Objective: The aim was to investigate the effect of different interfacial surface treatments on the shear bond strength (SBS) between a short fiber-reinforced flowable composite (SFRC) and a particulate-filled flowable composite (PFC). In addition, SBS between two successive layers of similar materials was evaluated. Materials and methods: One-hundred and forty-four specimens were prepared having either SFRC (everX Flow) as a substructure composite and PFC (G-aenial Flo X) as a surface composite or having one of the two materials as both substructure and surface layer. Eight groups of specimens were created (n = 18/per group) according to the interfacial surface protocol used. Group 1: no treatment; Group 2: ethanol one wipe; Group 3: ethanol three wipes; Group 4: phosphoric acid etching + bonding agent; Group 5: hydrofluoric acid etching + bonding agent; and Group 6: grinding + phosphoric acid etching. Group 7: only PFC layers and Group 8 (control) only SFRC layers without any surface treatment. After one-day storage (37 °C), SBS between surface and substructure composite layers was measured in a universal testing machine, and failure modes were visually analyzed. SEM was used to examine the bonding surface of the SFRC composite after surface treatment. SBS values were statistically analyzed with a one-way analysis of variance (ANOVA) followed by the Tukey HSD test (α = .05). Results: The SBS between successive SFRC layers (Group 8) was statistically (p < .05) the highest (43.7 MPa) among tested groups. Surface roughening by grinding followed by phosphoric acid etching (Group 6) resulted in a higher SBS (28.8 MPa) than the remaining surface treatments. Conclusion: Flowable composite with glass fibers (everX Flow) showed higher interlayer SBS compared to PFC flowable composite. Interfacial surface roughness increases the bonding of PFC to the substructure of SFRC.

Influence of short-fiber composite base on fracture behavior of direct and indirect restorations.

OBJECTIVES: The aim was to examine the influence of short-fiber composite (SFC) core on the fracture-behavior of different types of indirect posterior restorations. In addition, the effect of thickness ratio of SFC-core to the thickness of the veneering conventional composite (PFC) on fracture-behavior of bi-structured composite restorations was evaluated. MATERIALS AND METHODS: MOD cavities with removed palatal cusps were prepared on 90 intact molars. Five groups of direct overlay restorations (n = 10/group) were fabricated having a SFC-core (everX Flow) with various thicknesses (0, 1, 2, 3, 4 mm) and layer of surface PFC (G-aenial Anterior), remaining the thickness of the bi-structure restoration to be 5 mm. Four groups of CAD/CAM-made restorations (Cerasmart 270 and e-max CAD) were fabricated either with 2-mm layer of SFC-core or without fiber reinforcement. Intact teeth (n = 10) were used as control group. Restorations were statically loaded until fracture. Fracture patterns were evaluated visually. Data were analyzed using ANOVA (p = 0.05). RESULTS: With indirect overlay restorations, no statistically significant differences (p > 0.05) were observed in the load-bearing capacities between restorations reinforced by 2-mm SFC-core (bi-structured) and those fabricated from plain restorative materials. ANOVA displayed that direct overlay restorations made from 4-mm layer thickness of SFC-core had significantly higher load-bearing capacities (3050 ± 574 N) (p < 0.05) among all the groups tested. CONCLUSIONS: Restorations (direct/indirect) combining SFC-core and a surface layer of conventional material demonstrated encouraging achievement in reference to fracture behavior. CLINICAL RELEVANCE: The use of flowable short-fiber composite as reinforcing base with large direct and indirect restorations may result in more repairable failure.

Microstructure and Surface Characteristics of Short- Fiber Reinforced CAD/CAM Composite Blocks.

OBJECTIVE: The aim was to investigate certain surface properties and microstructure of an experimental short fiber-reinforced CAD/CAM composite block (SFRC) in comparison with different CAD/CAM, 3D-printing and manually-made commercial composites (Cerasmart 270, GC Temp PRINT, Pro3dure GR-17, Essentia U, Gradia Plus and everX Flow). METHODS: A wear-test was performed using a chewing-simulator with 15000 cycles. Wear depth (n=6) was assessed by 3D optical-profilometer. Surface roughness (SR) before and after wearing-test was evaluated. A Vickers-indenter was utilized for evaluating surface microhardness (VH) and glossmeter was utilized to measure the surface gloss at 60°. The surface microstructure of each composite was investigated with SEM. Data were statistically analyzed with analysis of variance ANOVA (p=0.05). RESULTS: Significant differences in the surface properties were found according to the type of composite (p⟨0.05). Cerasmart 270 exhibited the highest VH (94.8 V) and lowest SR (0.18 Ra) values (p⟨0.05) among the composites tested. The lowest wear depth measurement was located for GC Temp PRINT (19.3 µm) which was not significantly different (p⟩0.05) from Cerasmart 270 (20.7 µm). CONCLUSION: Incorporation of fibers to the composite of the CAD/CAM block did not negatively influence the surface characteristics of composite.

Influence of Short Fiber- Reinforced Composites on Fracture Resistance of Single-Structure Restorations.

OBJECTIVE: The aim was to determine the load-bearing capacity of anterior crowns prepared using two types of single-structure short fibre-reinforced composites (SFRCs). Furthermore, fracture toughness (FT), flexural strength (FS) and flexural modulus (FM) of tested composites were measured. METHODS: Seven groups of composite crowns were designed for an upper central incisor (n=8/group). Two groups were CAD/CAM fabricated made of Cerasmart 270 and experimental single-structure SFRC blocks. Two groups were 3D-printed made of GC Temp PRINT and Pro3dure GR-17 composites. Two groups were made of conventional light-cured composites (Essentia and Gradia Plus). The last group was a single-structure SFRC made of commercial flowable SFRC (everX Flow). Crown restorations were loaded until fracture. Failure-modes were then visually examined. FT, FS and FM were determined for each tested composite (n=8). The data were analysed using analysis of variance (p=0.05) followed by Tukey's post-hoc test. RESULTS: ANOVA revealed that crowns made of experimental SFRC blocks had significantly higher load-bearing capacities (1650 ±230 N) (p⟨0.05) among all the groups tested. Experimental SFRC blocks exhibited the highest FT (2.9 MPa m1/2) and FS (245.8 MPa) values (p⟨0.05) among tested composites. CONCLUSION: CAD/CAM fabricated restorations made of experimental SFRC blocks demonstrated encouraging performance related to their fracture-behaviour.

Fiber Reinforcement of Endodontically Treated Teeth: What Options Do We Have? Literature Review.

The restoration of endodontically treated teeth (ETT), even though practiced for many years, remains a major concern in dentistry. There is a variety of materials and clinical techniques advocated for restoring ETT and hundreds of studies devoted to this subject have been published in the dental literature. This narrative review article was undertaken to answer a question regarding restoration of ETT with available evidence: What fiber reinforcement options do we have other than prefabricated fiber post? Using a Medline search (up to 2019) and resulting cross-references, authors selected original research on the topic of fiber-reinforced composite (FRC) and restoration of ETT. Of the assessed articles selected (n=79), most were laboratory-based research with various test specimen designs and only 15 articles were clinical reports. From the reviewed studies, using individually formed FRC posts and short-FRC resin showed promising characteristics, and therefore, might be recommended as an alternative treatment option in restoring ETT. However, long-term clinical trials are needed in order to evaluate the usefulness of these alternatives.

Preliminary clinical evaluation of short fiber-reinforced composite resin in posterior teeth: 12-months report.

This preliminary clinical trial evaluated 12 month clinical performance of novel filling composite resin system which combines short fiber-reinforced composite resin and conventional particulate filler composite resin in high stress bearing applications. A total of 37 class I and II restorations (compound and complex type) were placed in 6 premolars and 31 molars. The restorations were reviewed clinically at 6 months (baseline) and 12 months using modified USPHS codes change criteria for marginal adaptation, post-operative sensitivity, pulpal pain and secondary caries criteria. Photographs and x-rays were obtained for restorative analysis. Results of 12 months evaluation showed 5 restorations having little marginal leakage (B score) and 1 patient had minor pulpal symptom and post-operative sensitivity (B score). No secondary caries or bulk fracture was detected. The majority of restorations exhibited A scores of the evaluated criteria. After 12 months, restorations combining base of short fiber reinforced composite resin as substructure and surface layer of hybrid composite resin displayed promising performance in high load bearing areas.

Fiber-reinforced Composite for Chairside Replacement of Anterior Teeth: A Case Report.

A variety of therapeutic modalities, from implant to conventional Maryland prosthesis, can be used for the replacement of a missing anterior tooth. Whenever a minimal tooth reduction is preferred, a fiber reinforced composite (FRC) prosthesis could be a good alternative to conventional prosthetic techniques, chiefly as temporary restoration before making a final decision on the treatment. The purpose of this case report is to describe the clinical procedure of fabricating anterior chairside FRC prosthesis with pre-impregnated unidirectional E-glass fibers and veneered particulate filler composite. Fiber-reinforced composite in combination with adhesive technology appears to be a promising treatment option for replacing missing teeth. However, further and long-term clinical investigation will be required to provide additional information on the survival of directly-bonded anterior fixed prosthesis made with FRC systems.