Fabrication and Experimental Analysis of Treated Snake Grass Fiber Reinforced with Polyester Composite

The selection of fiber is predominant for natural fiber-reinforced polymer composite materials, which should have easy extraction and good bonding with considerable strength. In this paper, some chemical treatments were done on the fiber material to increase interfacial bonding between the snake grass fiber (Sansevieria ehrenbergii) and polyester matrix, such as alkali treatment (NaOH), potassium permanganate treatment, sodium carbonate treatment, hydrogen peroxide treatment, and calcium carbonate treatment. The chopped snake grass fiber-reinforced polymer composite material was prepared by keeping 25 wt.% of fiber and 30 mm fiber length reinforced with an unsaturated polyester resin that was cured with the help of the catalyst methyl ethyl ketone peroxide (MEPK). Cobalt naphthenate was used as an accelerator. Tribological properties were discussed for the highly potential sample with the help of a pin-on-disc wear tester, and the results were analysed by the Taguchi L9 orthogonal array. This paper exhibited the best mechanical and tribological properties among those chemical-treated fibers used in fiber-reinforced composite materials and untreated fibers used in fiber-reinforced composite materials. CaCO3 treatment provided higher tensile strength (45 MPa), impact strength (3.35 J), and hardness (27 BHN). Finally, the mechanical and tribological characterization of the samples was done with the aid of SEM (scanning electron microscope).

Ex Vivo Assessment of Natural Teeth Wear against Zirconia and Novel Glass-Fiber-Reinforced Composite Crowns in Primary Teeth by a Three-Dimensional Assessment Method

Objectives. The main purpose of the study was to assess the material wear, antagonistic natural primary teeth wear, and microhardness of zirconia (ZR), a recently launched novel glass-fiber-reinforced composite crown (GFRC). The research question was, are these aesthetic crowns resulting in antagonistic natural primary tooth wear and the crown material itself? Methods. Forty-five primary canines were divided into three groups (15 per group) and mounted against Zr (Group A), GFRC (Group B), and natural teeth as control (Group C) in the wear test machine. All samples were assessed for surface wear with pre- and post-3-dimensional scanning. In addition, microhardness was assessed for all three groups. Results. The mean microhardness value for the Zr disc was 1157 ± 7 HV; for the GFRC disc, it was 29.35 ± 2 HV; while with natural teeth, it was 105 ± 4 HV. There was a statistically significant difference in teeth wear in the prescan and postscan in the natural tooth ( p < 0.05 ) group, highly significant difference ( p < 0.001 ) in the ZR group, and no significant difference in the GFRC group. Conclusion. There is more significant wear loss of glass-fiber-reinforced composite discs as compared to zirconia. In addition, the wear of the antagonistic tooth with zirconia and natural teeth is more remarkable than with GFRC. There is a vast difference of microhardness between natural teeth and zirconia (almost 10 times higher) which suggests further scope of study. Clinical Relevance. Pediatric dentistry deals with the transition of dentition from primary to permanent through mixed dentition. Selection of restorative material needs to be done cautiously when we are dealing with primary teeth and young permanent teeth as antagonistic teeth. Wear of the crown material itself and opposing natural teeth are essential factors that should be considered in selecting crowns in clinical practice. The present study results can be extrapolated to clinical practice, and the practitioner can consider various factors in selecting full-coverage crowns for primary teeth. The vast difference in aesthetic crowns and natural teeth microhardness indicates a further need for research. Additionally, there is no literature published for the recently launched GFRCs.

Survival of Fiber-Reinforced Composite Resin Post-Restored vs. Cast Post-and-Core-Restored Teeth: A Retrospective Clinical Study

Objective: The question of whether classic cast post-and-core (CPC) or fiber-reinforced composite resin posts (FRCP) are the best clinical decision has still not been fully solved. Materials and Methods: One hundred and sixty-two teeth were restored with FRCP, and 162 CPC restored teeth were included in this study with a matched-pair design. In a primary analysis, the survival rates after one year (primary endpoint) were compared. The additional analysis included an evaluation of tooth- and construction-specific variables and an illustration of the survival up to 60 months via Kaplan-Meier curves. Results: FRCP showed lower failure risk considering the definitive prosthetic restoration and tooth type compared to CPC restored teeth. In total, 17 failures were observed in the FRCP group and 35 failures in the CPC group. A 60-month survival rate of 79.3% for FRCP and 64.5% for CPC was observed. Teeth serving as abutments for telescopic dentures were more likely to be affected by failure compared to teeth restored with single crowns. Conclusion: Within the limitations of this study, the FRCP showed a lower failure risk compared to the CPC, considering the definitive prosthetic restoration and tooth type within the observation period.

Modular Paradigm for Composites: Modeling Hydrothermal Degradation of Glass Fibers

Fiber-reinforced composite materials are often used in structural applications in humid, marine, and offshore environments. Superior mechanical properties are compromised by environmental ageing and hydrolytic degradation. Glass fibers are the most broadly used type of fiber reinforcement to date. However, they are also most severely affected by environmental degradation. The glass fiber degradation rates depend on: (1) glass formulation; (2) environmental factors: pH, T, stress; (3) sizing; (4) matrix polymer; (5) fiber orientation and composite layup. In this short review (communication), seven modules within the Modular Paradigm are reviewed and systematized. These modeling tools, encompassing both trivial and advanced formulas, enable the prediction of the environmental ageing of glass fibers, including the kinetics of mass loss, fiber radius reduction, environmental crack growth and loss of strength. The modeling toolbox is of use for both industry and academia, and the Modular Paradigm could become a valuable tool for such scenarios as lifetime prediction and the accelerated testing of fiber-reinforced composite materials.