Evaluation of Residual Debris and Smear layer After Root Canal Preparation by Three Different Methods: A Scanning Electron Microscopy Study

Introduction: This study investigated the amount of debris and smear layer remaining followed chemomechanical preparation using three systems: ProTaper Universal, reciprocating SafeSider, and hand K-Flexofiles with scanning electron microscope (SEM). Materials and Methods: Sixty-five mandibular molars with mesiobuccal canal curvature (25 to 40°) were extracted and divided into one control group (n=5), and three experimental groups (n=20) according to the preparation method; K-Flexofile, ProTaper Universal and SafeSider instruments. All canals were irrigated with 3 ml of 5.25% sodium hypochlorite solution and 3 mL of 17% EDTA. Subsequently, the canals were irrigated with 5 ml of normal saline. Then the teeth were examined under the scanning electron microscope (SEM). Kruskal-Wallis, Dunn-Q Bonferroni, and Friedman tests were used for statistical analysis of results. Results: To assess the accumulation of debris, statistically significant differences were observed only in the coronal area among ProTaper Universal, SafeSider, K-Flexofile, and the control group. (P=0.029). To evaluate the residual smear layer amount, statistically significant differences were observed only in the coronal and middle areas, following the preparation of the canals using ProTaper Universal, SafeSider, and hand K-Flexofiles and control groups (P=0.019). Conclusions: Based on the present in vitro study, we can declare that the canals were utterly cleaned of debris and smear layer in none of the groups. Manual Flexofile and ProTaper Universal groups result in cleaner canal walls than reciprocal SafeSider, in the coronal and middle thirds

Evaluation of Antibacterial Effects of Cold Atmospheric Plasma, Calcium Hydroxide, and Triple Antibiotic Paste on Enterococcus faecalis Biofilm in the Root Canal System: An In Vitro Study

Introduction: One of the essential factors in successful endodontic therapy is effective cleaning and disinfection of the root canal. This study aims to determine the effect of the cold plasma on the infected root canals with Enterococcus faecalis and compare its antibacterial effect with the conventional medicaments in vitro. Methods: 63 single-root teeth were extracted. Canals were cleaned and shaped. Ten teeth were selected as a negative control randomly. The rest of the teeth were incubated at 37°C for 21 days to form Enterococcus faecalis biofilm. The specimens were divided into five groups; 2 positive control groups of medicaments and plasma, 1 group treated with calcium hydroxide; 1 group treated with 10 mg/ml of TAP; 1 group treated helium/oxygen plasma. After treatment, F4 Pro-Taper rotary file was used to collect root canal microbial biofilms. Bacterial suspensions are serially diluted, and the percentage of growth reduction for each group was obtained by dividing the logarithm of CFU /mL of each group by CFU /mL of the control of the same group. Results: The CFU/mL of TAP and plasma-treated samples was significantly lower than the control groups; however, there were no significant differences between the control group and samples treated by calcium hydroxide. The most percentage of CFU reduction was in the TAP-treated group compared with plasma and calcium hydroxide-treated groups. Conclusion: The application of cold plasma effectively inhibits the growth of Enterococcus faecalis and reduces bacterial biofilm. Also, in the present study, 10 mg/ml of TAP caused the complete elimination of Enterococcus faecalis. Calcium hydroxide had the most negligible effect on Enterococcus faecalis biofilm elimination

Effect of an Experimental Resin-based Sealer (Resil) and AH-26 on Postoperative Pain: A Randomized Controlled Clinical Trial

Introduction: One of the most common problems in endodontic treatments is post-treatment pain, and sealers might be one of the factors influencing the degree of pain following root canal therapy. The purpose of this study is to compare pain following endodontic treatment using an AH-26 resin sealer against the Resil experimental sealer in mandibular molars with irreversible pulpitis. Materials and Methods: One hundred patients with irreversible pulpitis in the mandibular first or second molar were randomly divided into two groups (n=50) based on the type of sealer applied. Two postgraduate students with at least five years of experience treated all patients. All patients had a single root canal treatment. Postoperative pain scores and analgesic consumption were assessed after 6, 12, 24, and 48 hours and 3, 4, 5, 6, and 7 days after the treatment. The data were statistically analyzed by Fisher's exact or Chi-Square test (to compare the distribution of qualitative variables in two groups), repeated measures ANOVA (to compare changes in pain intensity over time in two groups), Boneferronie (for pairwise comparisons), Friedman, Wilcoxon and Mann-Whitney tests (for assessment of the changes in pain scores over time). The generalized estimating equations (GEE) were used for assessing time and group effects. Results: There was no significant difference in postoperative pain between groups at any of the time points studied (P>0.05), and also for patient analgesic consumption between groups (P>0.05). Both groups recorded the maximum pain levels in the first 6 hours. For each subsequent day postoperatively, the odds ratio (OR) of not using analgesics was 2.078. Conclusion: Resil and AH-26 perform similarly in terms of the occurrence and intensity of postoperative pain in mandibular molar teeth with irreversible pulpitis

The The Effect of Low-Level Laser Therapy on the Viability of Human Dental Pulp Stem Cells: Effect of LLL on the viability of DPSCs

Objectives: This study assessed the effect of low-level laser (LLL) irradiation on the viability of dental pulp stem cells (DPSCs). Materials and Methods: In this in vitro experimental study, human DPSCs were purchased from the cell bank of Iranian Genetic Resources and cultured in flasks containing Dulbecco's modified Eagle's medium supplemented with 20% fetal bovine serum (FBS) at 37°C, 5% CO2, and 95% humidity. The cells were stored in semi-confluent form, and the culture medium was refreshed every two days. The cells in the control group were not laser-irradiated. The cells in the experimental groups were irradiated with 660 and 808 nm diode lasers with 4.1 J/cm2 energy density. Cell viability was assessed at baseline and after 24, 48, and 72 hours using the methyl thiazolyl tetrazolium (MTT) assay. The effects of laser irradiation, laser wavelength, and time on the percentage of cell viability were analyzed by two-way ANOVA and Tukey's test. Results: The effects of laser irradiation and its wavelength (P=0.04), time of assessment (P<0.001), and the interaction effect of group and time (P=0.02) on cell viability were significant. Cell viability in 660 and 808 nm laser groups at 48 and 72 hours was higher than that of the control group; however, statistically, only the difference in cell viability between the 660 nm laser and control group at 72 hours was significant (P=0.03). Conclusion: Considering the optimal effect of diode laser irradiation (particularly 660 nm) on the viability of DPSCs, it may be suitable for relevant clinical applications