Evaluation of surface alterations in different retreatment nickel-titanium files: AFM and SEM study

The aim of this study was to evaluate the surface changes of nickel titanium (Ni-Ti) rotary retreatment files after three and five uses. Furthermore, the effects of 2% sodium hypochlorite and chloroform solutions and sterilization procedures on the NiTi rotary retreatment surfaces were investigated. ProTaper Retreatment files, R-endo files, and Mtwo retreatment files were used for this study. The palatinal roots of maxillary molar teeth were obturated with gutta percha and Ah26. Retreatment procedures were performed with these retreatment file systems. The surface changes of untreated NiTi rotary files that were used three and five times, immersed in NaOCl and chloroform and subjected to sterilization procedures were investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The RMS values, three dimensional images and SEM images at various magnifications were obtained. RMS values showed that all three NiTi rotary retreatment file systems showed significant deteriorations after three and five uses. Cracks, damages and spiral construction deteriorations were detected in the SEM images after three and five uses. Furthermore, the Mtwo 15 file was broken off after five uses. AFM data indicated that 2% NaOCl caused significant surface deteriorations on NiTi rotary files and both AFM and SEM evaluation showed that chloroform solution and sterilization procedures did not cause significant surface deteriorations. In conclusion, ProTaper retreatment, R-endo, and Mtwo retreatment files showed surface damages depending on retreatment procedures. Clinicians have to consider that retreatment files always have a tendency to break off after the third time they have been used. © 2015 Wiley Periodicals, Inc

Evaluation of antimicrobial and thermal effects of diode laser on root canal dentin

Objectives: The aim of this study was to evaluate the antimicrobial effects of diode laser and temperature rise on the root surface during application. Materials and Methods: Thirty-six teeth were chemomechanically prepared and irrigated with 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid, and then autoclaved and incubated with a suspension of Enterococcus faecalis. The specimens were randomly divided into three groups (n = 12): Group 1, irradiated by diode laser at 1.2 W; Group 2, irradiated by diode laser at 2 W; and Group 3, irradiated by diode laser at 3 W. The grown bacteria were counted and the mean numbers of the each test tube were determined. The temperature was measured on the external apical third of the root during laser application. The mean values of results for each group were compared using one-way analysis of variance and Tukey test. Results: No significant difference was obtained among the test groups in terms of the colony counts (P > 0.05). According to the temperature changes, there was a significant difference between groups (P < 0.05). Temperature rises were 16.79°C, 10.20°C, and 6.25°C in Group 3, Group 2, and Group 1, respectively. Conclusion: Diode laser irradiation with 1.2 W demonstrated comparable performance with 2 W and 3 W power sets for elimination of E. faecalis from root canal with less temperature rise. © 2018 Nigerian Journal of Clinical Practice | Published by Wolters Kluwer - Medknow

Determination of the effect of Nd:YAG laser irradiation through dentinal tubules on several oral pathogens

The effects of Nd:YAG laser irradiations at different power settings on several oral pathogens were evaluated. A total of 252 dentin samples were divided into seven groups consisting of 36 dentin specimens each. In each group, 9 of the 36 specimens were used as controls, thereby including a control in every group. The remaining 27 specimens were divided into three subgroups consisting of nine specimens according to different Nd:YAG laser settings (1.5, 1.8, and 2 W). Each group was inoculated on the nonpulpal side with one of the following microorganisms: Candida glabrata, Candida tropicalis, Candida krusei, Candida sake, Candida lusitaniae, Candida kefyr, and Rhodotorula mucilaginosa. The following irradiation procedure was used: the specimens were irradiated on the bacteria-free side (the side consisting of the pulpal wall) using contact mode under the constant scanning movement of the optical fiber at an angle of 10A degrees. One lasing cycle consisted of four irradiation cycles of 10 s each, with 15-s intervals in between each irradiation cycle. The remainder of the controls and the lased specimens of each group were prepared for the microbiological investigation. After incubation for 24 h at 37 A degrees C, the colonies were counted, and the total number of surviving microorganisms was statistically assessed. Microorganisms irradiated with Nd:YAG laser at power settings 2 W, 15 pps did not survive. Although there was a significant reduction of microorganisms at 1.5 and 1.8 W, when comparing Nd:YAG laser irradiation with the control group, sterilization did not occur

Microhardness of packable composites used as posts condensed with different methods

PubMedID: 14760909The purpose of this in vitro study was to evaluate the microhardness of packable composite compacted with hand or ultrasonic pluggers in post spaces. A total of 168 extracted human anterior teeth were prepared with Gates Glidden and ParaPost drills after obturation. A primer and a dentin-bonding agent were applied to the etched surface. Half of the specimens were compacted with an ultrasonic tip and the other half with a mechanical hand compactor and all specimens were polymerized for each increment. The roots were then sectioned horizontally from 0, 2.5, 3, 3.5, 4, 4.5, and 5 mm starting from the coronal and sliced 2.5-mm long. The microhardness test was applied to each specimen. There were statistically significant differences between ultrasonically and hand-condensed groups in whole specimens (p < 0.001). There were no significant differences between groups of 0, 2.5, and 3 mm until 3.5 mm was reached. After 3.5-mm depth, there were significant differences between the groups (p < 0.001). Ultrasonic condensation of packable composites provided mechanical advantage over hand condensation in root canals measuring microhardness in different depths. However, when microhardness was measured at different depths, values decreased after the depth of 3.5 mm in both condensation groups

Evaluation of antimicrobial and thermal effects of diode laser on root canal dentin.

The aim of this study was to evaluate the antimicrobial effects of diode laser and temperature rise on the root surface during application