This study investigated the shaping abilities of XP Shaper and compared it with other single file NiTi systems using full rotation and reciprocation motion by cone beam computed tomography. Mesiobuccal canal of forty-five mandibular first molars, were divided into three equal groups, using WaveOne, OneShape and XP shaper. Pre-and post instrumentation images were obtained at 3mm, 5mm and 7mm from the apex and were assessed to determine canal transportation and centering ability. Data were analyzed using Kruskal-Wallis test for comparing the three systems, while Friedman's test was used to compare between the root levels. WaveOne and OneShape showed the highest mean amount of transportation with no statistically significant difference between them. XP Shaper showed the lowest statistically significantly mean amount of transportation. There was a statistically significant difference in the canal centring ability among the three instruments used. It was concluded that XP shaper preserved the original canal shape better than WaveOne and OneShape.

Within the parameters used in this study, a combination therapy consisting of irrigation followed by diode laser irradiation should be utilized as an effective treatment modality for eliminating E. faecalis from root canal systems.

Objective:The aim of the present study was to compare the canal transportation, centering ratio, debris and smear layer score after using 3 rotary Ni-Ti systems, Revo-S (RS; Micro-Mega, Besancon Cedex, France) and ProTaper Next (PTN; Dentsply Tulsa Dental Specialties, Tulsa, OK) and M-Pro system( Guangdong, China, Mainland). Material and methods: Thirty nine mesiobuccal root canals of extracted lower first molars with 20˚ to 45˚ angle of curvature and were divided randomly into 3 groups of 13 samples each: group RS, group M-Pro and group PTN. Root canal transportation and centering ratio were evaluated at 3, 6 and 9 mm from apex using i-CAT CBCT (Hatfield, pennsylvania ,USA) before and after preparation.Thirteen Roots from each group were split longitudinally using diamond disc, by making a groove on buccal and lingual side of root without reaching the lumen of the canal.The root halves were examined under Scan Electron Microscope (SEM) by magnification x 1000 and x 4000 for debris and smear layer respectively The significance level was set at P ≤ 0.05. Results: There was no statistically significant difference in canal transportation, canal centering ratio, debris and smear layer score between the three tested groups. Conclusion: From the obtained results and within the limitations of this study, the following could be concluded:M-Pro Nickel Titanium rotary system had a negligible effect on root canal transportation which was similar to the ProTaper Next and Revo-S systems and no system was able to clean the root canal system completely.

This study was conducted to evaluate the efficacy of 0.2% Chitosan Nanoparticles (CNPs), CNPs/EDTA (1:1) and 17% EDTA on smear layer removal ability.Methods: Fifteen extracted human permanent mandibular premolars with single canals were decoronated and biomechanically prepared using protaper next rotary system and 2.5% Sodium hypochlorite, then randomly distributed according to the final irrigation protocol into 3 group; Group I (0.2% CNPs), Group II (CNPs/EDTA) (1:1), and Group III (17% EDTA). A standardized volume of 5 ml of each tested irrigant (s) was used for 3 minutes. Teeth were longitudinally split to evaluate the smear layer eradication using scanning electron microscope at magnifications of 500x and 1000x. The micrographs for each third were given scores by two blinded observers using Takeda., et al. (1999) scoring system.Results: There was no statistically significant difference in the scores of the three groups at the coronal, middle, and apical thirds (Pvalue = 0.368, 0.054, and 0.0900) respectively. As for the combined total scores of each group, Group I (CNPs) showing a significantly higher smear layer elimination than both Group II (CNPs/EDTA) and Group III (EDTA) (P-value = 0.044).Conclusions: None of the used chelating agents resulted in complete removal of the smear layer. The combined use of CNPs/EDTA (1:1) did not show superior performance over the other two groups.

Objectives: The purpose of the study was to assess the amount of residual root canal filling materials (Guttapercha/Bioceramic sealer) after using different irrigation protocols. Methodology: FortyMandibular premolar teeth were mechanically instrumented using Protaper Next rotary system and obturated with guttapercha master cones (size 25, 0.06 taper) coated with Sure Seal bioceramic sealer (Sure Dent Corp., Gyeonggi-do, Korea). All specimens were incubated for 4 weeks then retreatment was performed using Protaper Universal retreatment system. The specimens were randomly divided into four equal groups (n=10) according to the final irrigation protocol as follow; Conventional needle irrigation, Endovac, UltraX, Passive ultrasonic irrigation. Roots were grooved buccolingualy into two halves. A digital camera connected to the stereomicroscope captured images to each half. The root canals were segmented into thirds (Apical, middle and coronal). Image-J softwarewas used to evaluate and measure the areas with the remaining filling material in each third. Data were analysed using One-way ANOVA followed by Tukey's post hoc test for intergroup comparisons while One-way repeated measures ANOVA was used for intra group comparisons. Results: All groups showed residual filling material in the root canals. The amount of the residual filling materials was significantly reduced upon using passive ultrasonic irrigation (P<0.001). Conclusion: None of the irrigant activation methods was capable of completely removing the root canal filling material. Passive Ultrasonic irrigation enhanced the retreatment procedure of root canals previously obturated with gutta percha/bioceramic sealer.