Objective. Cyclic fatigue occurred in the curved canal when the instrument freely rotated leading to repeated compressive and tensile stresses. This study aims to evaluate the cyclic fatigue resistance (CFR) of new and used 2Shape and AF F-One rotary instrument systems by using an artificial stainless-steel canal. Methods. A total of 80 rotary nickel–titanium (NiTi) instruments of two systems were used, 2Shape/TS2 and AF F-ONE/F5 (40 in each group). The instruments were subdivided into group A 20 instruments (10 per system) that remain unused, group B 20 instruments (10 per system) instrumented 20 root canals (each file prepared 1 canal for 2 minutes), group C 20 instruments (10 per system) instrumented 40 canals each for 2 minutes (each file prepared 2 canals), group D of 20 instruments (10 per system) prepared 60 canals each for 2 minutes (each file prepared 3 canals). After each canal instrumentation, the instruments were cleaned and sterilized by autoclave. Then, all the instruments underwent cyclic fatigue testing in an artificial stainless steel canal with a 50° canal curvature and a radius of curvature of 5 mm. The time and number of cycles to failure (NCF) were recorded. Data were analyzed using the Welch ANOVA test for intragroup comparison and the pairwise test for multiple comparisons. Results. The unused instruments of the AF F-One rotary system showed statistically higher CFR than clinically used instruments ( P < 0.05 ). 2Shape system was not affected by clinical use ( P > 0.05 ). The mean NCF of AF F-One instruments was significantly higher than the equivalent file group of 2Shape instruments ( P < 0.05 ). Conclusion. A reduction in the CFR for AF F-One instruments after use was observed when compared to the new unused file group. The 2Shape system was not affected by clinical use. AF F-One performed better in terms of NCF.
Surface qualities for resin composite restorations are important factors for any successful restoration. Thus, finishing and polishing procedures are paramount to achieving acceptable aesthetics and guaranteeing the longevity of composite restorations. This in-vitro study aimed to evaluate the influence of a one-step polishing system on the surface roughness of three bulk-fill composite resin materials. This article provides a new view into the effects of finishing and polishing on bulk-fill composites, which has received very little research. Hence, this in-vitro study was conducted to extensively evaluate the impact one-step polishing technique has upon the three bulk-fill composite resin materials' surface roughness. A total of thirty discs were prepared from three commercial resin composite [Filtek One Bulk-Fill (3M), Tetric EvoCeram Bulk-Fill (Ivoclar Vivadent), and Ecosite Bulk-Fill(DMG)] using a stainless-steel flat washer. The composite material was condensed within a mold and cured with light Intensity 1000 mw/cm for 20 seconds. All specimens were divided into three groups (n = 10): (1) EvoCeram, (2) Ecosite group, and (3) Filtek group. A single operator polished all specimens. The top surface of each sample was finished with a fine-grit tungsten carbide bur (X-mas Tree with Safe End, NTI-Kahla GmbH, and Germany) for 30 seconds. Then all specimens were polished for 30 seconds by using the OneGloss one-step polishing system. A calibrated mechanical profilometer was used to measure the Ra for each material. The lowest roughness value (0.19) was observed for the composite resin Tetric EvoCeram (Ivoclar). One-way ANOVA and LSD test showed significant differences among and between all experimental groups. Therefore, Tetric EvoCeram had the only clinically acceptable Ra values.
Evaluation of composite resin microleakage with using different bonding agents by micro computed tomography Conclusion: Newer adhesive systems have better success achievements and recommended to be used in practical bases.
Background and objective: During root canal instrumentation irrigants, necroticpulp tissue, microorganism and dentin debris may be extruded beyond the apexinto the periradicular tissue. These extrusions may cause flare-up. The purpose ofthis study was to compare the amount of apically extruded debris with three rotaryNickel titanium instruments.Methods: Sixty single rooted, single canalled premolars were selected. The rootswere divided randomly into three groups; (n = 10) according to the type ofinstrumentation system used, group 1“ProTaper Next” system, group 2 “OneShape” system and group 3 “Mani Silk” system. The Debris extruded during theinstrumentation was collected and dried in preweighed vials and the amount ofextruded debris was assessed with an electronic balance.Result: results showed that the Mani silk system extruded significantly less debristhan the ProTaper Next and One shape systems (P < .05), and there is nosignificant difference in apically extruded debris between ProTaper Next groupand One Shape group but the One Shape produced more debris than ProTaperNext.Conclusion: the Mani silk file instrument was behaved well during instrumentationand extruded less debris than the other groups.
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