Evaluation of Canal-centering Ability and Apical Transportation of Hyflex-EDM, OneShape, WaveOne Gold, and Reciproc Files: An Ex Vivo Study.

AIM: To evaluate and compare canal-centering ability (CCA), canal transportation (CT), and dentinal crack formation by using Hyflex-electrical discharge machining (EDM), OneShape, WaveOne Gold, and Reciproc single file system in the mesiobuccal root of maxillary first molar at coronal, middle, and apical third using cone-beam computed tomography (CBCT) and scanning electron microscopy (SEM). MATERIALS AND METHODS: Mesiobuccal roots of 120 freshly extracted maxillary molar teeth were divided into four experimental groups; Hyflex-EDM, OneShape, WaveOne Gold, and Reciproc (n = 30/group). Preinstrumentation scanning was done using CBCT for all samples at coronal one-third (4 mm), middle one-third (8 mm), and apical one-third (12 mm). After cleaning and shaping with standard irrigation protocol, the specimens were again scanned. Canal-centering ability and CT were calculated using pre- and postinstrumentation CBCT values. A scanning electron microscope was used to identify dentinal crack formation. RESULTS: No significant difference was found for CCA by any of the systems at coronal, middle, and apical third, respectively. However, OneShape was found to have better CCA at the coronal third and WaveOne Gold at the middle and apical third. There was a significant difference in canal transportation at the apical third (p = 0.004) with WaveOne Gold having the least CT followed by Reciproc at the apical third. OneShape resulted in more dentinal cracks in the coronal and middle thirds. Also, Hyflex-EDM was better in the apical third. CONCLUSION: No difference in CCA was observed between the groups. The lowest values for CT were obtained for WaveOne Gold (similar to Reciproc) whereas both rotary files showed higher values for CT. Also, OneShape showed the most dentinal at all levels. Furthermore, Hyflex-EDM and WaveOne Gold produced the least dentinal cracks at all levels. CLINICAL SIGNIFICANCE: Given that the Reciprocating file system had the least CT and least dentinal cracks, the clinical success rate of root canal treatment (RCT) with the Reciprocating file system can be a better choice to improve the longevity of root canal-treated teeth.

Evaluation of Compressive and Flexural Strengths of Two Resin-based Core Materials with an Alkasite Material: An In Vitro Study.

AIM: To compare and evaluate the compressive and flexural strengths of two resin-based core build-up materials with an alkasite material. MATERIALS AND METHODS: ParaCore, Tetric N ceram Bulk-fill composite, and Cention N were used. A total of 90 specimens were prepared. Customized cylindrical split molds of dimension 6 ± 1 mm (height) × 4 ± 1 mm (diameter) were used to fabricate 15 samples of each core material for testing the compressive strength and rectangular split metal molds of dimensions 25 ± 1 mm (length) × 2 ± 1 mm (width) × 2 ± 1 mm (height) were used to fabricate 15 samples of each core material for testing the flexural strength. Then the samples were tested using a Universal testing machine (UTM). RESULTS: The compressive and flexural strengths of Cention N were significantly less than ParaCore® but higher than Tetric® N-CeramTM Bulk-fill core build-up material. CONCLUSION: Within the limitations of this study, it was concluded that Cention N may be used as an alternative to other core build-up materials after further in-vitro and in-vivo studies. CLINICAL SIGNIFICANCE: Cention N had the added advantage that self-cure polymerization alone was sufficient to achieve good physical properties when compared to the other two resin-based core build-up materials.

Comparative Evaluation of Bactericidal Effect of Silver Nanoparticle in Combination with Nd-YAG Laser against Enterococcus faecalis: An In Vitro Study.

AIM AND OBJECTIVE: To evaluate the bactericidal effect of silver nanoparticles and silver nanoparticles in combination with Nd-YAG laser against Enterococcus faecalis. MATERIALS AND METHODS: A solution containing 100 µg of silver nanoparticles in 1 mL was prepared by adding 5 mL of 10-4 M solution of AgNO3 with 5 mL of 0.1 M sodium tricitrate. Synthesized silver nanoparticles were characterized using UV-visible spectrophotometer for optical studies and the transmission electron microscopic analysis for determining the size and shape of the nanoparticles. Groups are as follows: group I-silver nanoparticles against E. faecalis, group II-silver nanoparticles in combination with Nd-YAG laser against E. faecalis, group III-control, E. faecalis bacterial culture alone. Optical density was measured periodically at half an hour interval in spectrophotometer in a 96 well plate and statistically analyzed using one-way ANOVA. RESULTS: The optical density and turbidity of groups I and II began to decrease in 2 hours in comparison with the control. There was a significant difference in mean optical density among the three groups after 1½ hours onward. The study also demonstrated the minimal bactericidal concentration (MBC) as 100 µg/mL of Ag nanoparticles with a size of 15 nm were effective against E. faecalis. CONCLUSION: The study concluded that silver nanoparticles individually and in conjunction with Nd:YAG laser irradiation would be an effective protocol against E. faecalis. CLINICAL SIGNIFICANCE: The combined effect of silver nanoparticles and laser disinfection against E. faecalis holds a promising treatment modality for eradicating resistant pathogens and biofilms embedded deep inside the dentinal tubules that are not amenable to conventional disinfection protocols in root canals.