To compare the effects of different irrigation protocols, with/without laser activation, on the radicular dentine's micro-hardness. Methods: Eighty-two human extracted premolars were decoronated and divided into 7 groups. Roots were longitudinally split into two halves. The micro-hardness was measured for one half before and after irrigation protocols. The groups were; G1: MTAD without laser-activation, G2: MTAD with laser-activation, G3: sodiumhypochlorite (SH) with laser-activation, G4: SH then EDTA with laser-activation, G5: SH then MTAD with laseractivation, G6: SH without laser-activation. G7: distilled water (control). In the two-irrigants groups G4 and G5), samples were irrigated first with SH then with MTAD or EDTA irrigants, which were activated by the laser. The difference between the before-and after-irrigation micro-hardness was calculated to obtain the microhardness difference. Data were analyzed using the Paired Sample-t and Two-ways ANOVA tests at P=0.05. Results: Overall, the mean dentine's micro-hardness after-irrigation (103.1) was lower than before-irrigation (116.1) (P<0.001); except for the distilled-water group, (116.6 and 112.9, respectively) (P=0.075). The microhardness reduction of SH without laser-activation group (32.5) was the greatest (P<0.001). The single-irrigant or laser-activation irrigation protocols caused significantly less micro-hardness reduction compared to the two-irrigants or no laser-activation protocols. The mean micro-hardness reduction of SH and MTAD groups (both with laser-activation) (5.8 and 9.3, respectively) were significantly lower than other groups, but not from that of the control group (3.7). Conclusion:Using irrigants significantly reduced the root-dentine's micro-hardness. Although irrigants agitation by an Er: Yag laser significantly minimized micro-hardness reduction, it did not suppress the adverse effects on dentine micro-hardness when two-irrigants were used.
<p><strong>Objective: </strong>This study aimed to compare the fracture resistance of endodontically treated roots filled by different obturation systems. <strong>Material and methods: </strong>Ninety-six upper central incisors were used and decoronated, retaining 12 mm of the roots. On the basis of obturation systems, the roots were divided into 4 groups (n=24): Group1 (COGR): control group (unprepared, unfilled), Group 2 (AVGR): ActiV GP points/ActiV GP sealer, Group3 (GPGR): Gutta percha points/AH plus sealer, and Group4 (GAGR): Gutta percha points/ActiV GP sealer. The last three groups were obturated with the single cone technique. The roots were then stored in 100% relative humidity at 37 °C for 2 weeks. A vertical compressive force was exerted with a universal testing machine until a fracture occurred. Data were statistically analyzed with one-way ANOVA. <strong>Results</strong><strong>:</strong> Mean (SD) failure loads for groups ranged from 920.51 ± 210.37 to 1113.44 ± 489.42 N. The fracture resistance between the different study groups indicated no statistical difference. <strong>Conclusions:</strong> ActiV GP system did not exert a significant effect on the fracture resistance of endodontically treated teeth.</p>
This study aimed to evaluate the effectiveness of three rotary, single-file, and reciprocating systems in terms of preparation time and canal centralization in simulated highly curved root canal preparation. Materials and methodsThe study sample consisted of 45 simulated canals with a curvature of 40°. They were randomly distributed into three experimental groups: Group 1-Reciproc Blue; Group 2-WaveOne Gold; and Group 3-AF Blue R3. A glide path was established by #10 hand K-file, then red dye was colored on the simulated canals, and photographs of the sample were taken before preparation. Then, the canals of each group were prepared, and other photographs were taken after preparation. The images of the two phases were combined using AutoCAD, where the canal was divided into three parts and the preparation area was measured from the right and left sides of each part of the canal. The preparation time for each system was also measured. ResultsWhile there were no statistically significant differences in the rate of preserving canal centralization in the middle and apical thirds between preparation groups, a statistically significant difference was found in the coronal third, as the Reciproc Blue and WaveOne Gold systems have a greater ability to maintain the centrality of the canal compared to the AF Blue R3 system. While there were no statistically significant differences between the Reciproc Blue and WaveOne Gold systems in the coronal third, as for the preparation time, it was found that there were statistically significant differences in the preparation time between the groups in favor of the WaveOne Gold system. ConclusionBoth preparation systems (Reciproc Blue and WaveOne Gold) maintained the anatomical shape and canal centrality, with more cons for WaveOne Gold compared to the Reciproc Blue system. Regarding the volumetric changes, AF Blue R3 had the greatest changes compared to the Reciproc Blue and WaveOne Gold systems. WaveOne Gold Group, in terms of canal preparation time, showed the least time among the investigated groups.
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