AIM: The study aimed to evaluate the effect of placement of compactable glass fibers in reinforcing the endodontically treated teeth in a novel conservative manner.

SETTINGS AND DESIGN: Research laboratory, in vitro study.

MATERIALS AND METHODS: Seventy-five extracted maxillary premolars were procured. Fifteen teeth were left untreated (Group A) and the remaining teeth were endodontically treated followed by standardized mesio-occluso-distal preparation and randomly assigned to experimental groups (n = 15) as follows: (B) no restoration, (C) restoration with composite, (D) EverStick® POST followed by composite, and (E) vertical glass fibers within 3 mm of the coronal root canal space and buccopalatal flaring of the coronal fibers followed by composite. After conditioning and thermocycling, specimens were loaded under a universal testing machine to evaluate fracture resistance and fracture pattern of specimens.

STATISTICAL ANALYSIS USED: Obtained scores were statistically analyzed using one-way analysis of variance test for stress analysis, post hoc Tukey's test for intergroup comparison, and Chi-square test for analysis of favorable and unfavorable fracture.

RESULTS: The fracture resistance was highest to lowest as follows: Group A > E > C > D > B (P < 0.001).

Materials and Methods: Ninety J-shaped canals in resin blocks were filled with 2% Methylene Blue solution and pre-instrumentation images were taken using a Leica microscope at a ×10. They were prepared until size 25 taper 0.04 using (n = 18 per group): T-Flex, HyFlex CM, Vortex Blue, S5, and iRace. After instrumentation, images were captured again, and composite images were made using Adobe Photoshop imaging software. The differences in canal width and canal curvature at each respective landmark were measured and compared. The preparation time and canal abbreviations were also recorded. Statistical analyses were performed using one-way ANOVA and post hoc Tukey HSD tests. The level of statistical significance was set to P = 0.05.

Results: HyFlex CM demonstrated the least difference in canal width after instrumentation, but no significant difference (P > 0.05) as compared to T-Flex and Vortex Blue. The mean canal straightening ranged between 0.91° and 7.65°. T-Flex created the least canal straightening after instrumentation which was significantly less (P < 0.05) than S5, but there was no significant difference (P > 0.05) when compared to HyFlex CM. Instrumentation with the S5 file was significantly faster (P < 0.05), whereas HyFlex CM was the slowest.

Materials and Methods: A total of 40 extracted human maxillary anterior teeth were selected, disinfected, and decoronated to obtain a standardized length of 10 mm. The teeth were prepared with Protaper universal rotary files until size F4 using 2.5% NaOCl as an irrigant during instrumentation. The teeth were then randomly divided into four groups of 10 samples each based on the irrigating solutions used during final wash sequence as follows: Group A - (2.5% NaOCl and 2% CHX), Group B - (2.5% NaOCl followed by 70% Isopropyl Alcohol and 2% CHX), Group C - (2.5% NaOCl followed by 6.25% sodium metabisulfite and 2% CHX), and Group D - (2.5% NaOCl followed by 3.86% sodium Thiosulfate and 2% CHX). The roots were sectioned longitudinally and the canal surface was evaluated under dental operating microscope (×16) for the presence of orange-brown precipitate. The results were tabulated as per scoring criteria and statistically analyzed.

Statistical Analysis Used: One-way ANOVA test and post hoc Tukey's test.

Results: The lowest mean score was observed in Group C, followed by Group D and Group B, respectively. In comparison, there was a statistically significant (P < 0.001) difference in results between Group C and the other experimental groups. However, there was no statistically significant difference between Group B and Group D.

MATERIALS AND METHODS:  Overall, 180 samples were used for polymerization shrinkage (buoyancy and optical methods) and degree of conversion tests in which they were divided into Group 1, nanofilled composite (Filtek-Z350- XT; 3M ESPE, St Paul, MN 55144-1000, USA), Group 2, microhybrid composite (Zmack-Comp), and Group 3, nanohybrid composite (Zr-Hybrid). Polymerization shrinkage test was performed using buoyancy and optical methods. For buoyancy method, samples were weighed in air and water to calculate the shrinkage value, whereas, for optical method, images of nonpolymerized samples were captured under a digital microscope and recaptured again after light-cured to calculate the percentage of shrinkage. Degree of conversion was tested using Fourier-transform infrared spectroscopy spectrometer.

STATISTICAL ANALYSIS:  Data were analyzed using one-way analysis of variance complemented by post hoc Dunnett's T3 test for polymerization shrinkage and Tukey's honestly significant difference test for degree of conversion. Level of significance was set at p < 0.05.

RESULTS:  Group 3 demonstrated similar polymerization shrinkage with Group 1, but lower shrinkage (p < 0.05) than Group 2 based on buoyancy method. However, optical method (p < 0.05) showed that Group 3 had the lowest shrinkage, followed by Group 1 and lastly Group 2. Besides, Group 3 showed a significantly higher degree of conversion (p < 0.05) than Group 1 and comparable conversion value with Group 2.