Cyclic Fatigue Life of Two Single File Engine-Driven Systems in Simulated Curved Canals

Introduction: This study aimed to evaluate the cyclic fatigue resistance of two single file engine-driven instruments, Reciproc and NeoNiTi, in simulated root canals. Methods and Materials: Two groups of 15 NiTi endodontic instruments with an identical tip size of 0.25 mm were tested: Reciproc R25 (group A) and NeoNiTi A1 (group B). Cyclic fatigue testing was performed in a stainless steel artificial canal. The simulated canals had a 60° angle and 5-mm radius curvature. The Reciproc instruments were operated using the preset program on torque control electric motor specific for the Reciproc instruments, while the NeoNiTi instruments were operated using the manufacturer recommendation. All instruments were rotated until fracture occurred, and the number of cycles to fracture (NCF) and the length of the fractured tip were recorded and registered. Means and standard deviations of NCF and fragment length were calculated for each system and data were subjected to Student’s t test (P<0.05). Results: A statistically significant difference (P<0.05) was noted between Reciproc and NeoNiTi instruments. NeoNiTi A1 instruments were associated with a significantly higher mean NCF as compared to Reciproc R25 instruments (833±176 vs. 318±87 NCF). There was no significant difference (P>0.05) in the mean length of the fractured fragments between the instruments. Conclusion: NeoNiTi instruments were associated with a significantly higher cyclic fatigue resistance than Reciproc instruments.Keywords: Cyclic Fatigue; NeoNiTi; Reciproc; Single-File System

Effects of White Chicken Eggshell Powder on Compressive Strength, Water Solubility, and Setting Time of Calcium-Enriched Mixture

Introduction: The present study aimed to evaluate the effects of adding chicken eggshell powder (CESP) to calcium-enriched mixture (CEM) cement on its compressive strength (CS), solubility, and setting time. Materials and Methods: In this study, CESP was added at weight percentages of 3% and 5% to the powder component of the CEM cement. To measure the CS, a total of 36 samples (height, 6 mm; diameter, 4 mm) were tested in a universal testing machine. The setting time was assessed for 18 disk-shaped samples (diameter, 10 mm; height, 1 mm). Additionally, solubility test was performed on 18 samples (diameter, 8 mm; height, 1 mm) after 24 hours, 72 hours, seven days, and 14 days under dehydration conditions by calculating the weight changes; the results were then subjected to a normality test. Next, for the comparison of different test groups, parametric ANOVA test and post-hoc Tukey’s multiple comparison test were performed at a significance level of 0.05. Results: The addition of 5% CESP to the CEM cement significantly reduced its setting time and water solubility (P=0.02 and P=0.01, respectively). Moreover, it significantly increased the CS over a 21-day period (P<0.001). Additionally, the addition of 3% CESP also resulted in a significant increase in CS (P<0.001). While 3% CESP reduced setting time and water solubility, the difference was not statistically significant. Conclusion: The findings suggest that the addition of 5% CESP to CEM cement has the potential to improve its sealing ability, durability, and ability to withstand chewing forces in endodontic treatments. These results highlight the relevance of CESP as an additive for cement modifications and indicate its potential clinical implications

Nonsurgical Endodontic Treatment of a Maxillary Central Incisor with Two Separate Roots: A Case Report

The success of endodontic therapy requires knowledge of the internal and external dental anatomy and its variations in presentation. This case report involves endodontic treatment of a traumatized maxillary central incisor with two separate roots

The Ability of Triple Antibiotic Paste and Calcium Hydroxide in Disinfection of Dentinal Tubules

Introduction: The purpose of this in vitro study was to compare the ability of triple antibiotic paste (TAP) to calcium hydroxide (CH) in disinfecting dentinal tubules. Material and Methods: Sixty root blocks were obtained from extracted single-rooted human teeth. The root canals were enlarged with Gates-Glidden drills up to size 3 and were contaminated with Enterococcus. faecalis (E. faecalis), and then left for 21 days. The contaminated blocks were treated with saline (as negative control), CH or TAP. Dentin debris was obtained at the end of first and 7th days, using Gates-Glidden drills sizes 4 and 5 from two different depths of 100 and 200 µm. The vital bacterial load was assessed by counting the number of colony forming units (CFUs). The data was analyzed with the Kruskal-Wallis H and Dunn Post-Hoc tests. The Wilcoxon Signed Ranks test was used to check for differences in bacterial growth at both depths (P<0.05). Results: In comparison with CH, the TAP significantly decreased the number of CFUs in both depths and time intervals (P<0.001), while the CH group showed a moderate antibacterial effect. Conclusion: TAP is more effective in disinfecting the canal against E. faecalis compared to CH

Compressive Strength of Mineral Trioxide Aggregate and Calcium-enriched Mixture Cement Mixed with Propylene Glycol

Introduction: The aim of the present study was to evaluate and compare the compressive strength (CS) of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement when mixed with propylene glycol (PG). Methods and Materials: Twenty four custom-made split molds with 5 holes in each were prepared. Molds were allocated into eight groups (n=15 holes) as follows: Groups 1,5: CEM and MTA mixed with PG (100%), Groups 2,6: CEM and MTA mixed with PG (20% )+CEM or MTA liquid (80%) respectively, Groups 3,7: CEM and MTA mixed with PG (50% )+CEM or MTA liquid (50% ) respectively, Groups 4,8: CEM and MTA mixed with CEM or MTA liquid respectively as control groups. All specimens were kept in 37°C in an incubator and the compressive strength was evaluated after 7 days. Data were analyzed using the Kruskal Wallis and Dunne tests. The level of significance was set at 0.05. Results: In all concentration of PG, MTA samples showed better results than CEM cement. In CEM samples, adding 20% PG could significantly increase the compressive strength in comparison with control group and 100% PG (P=0.047 and P=0.011, respectively). In MTA samples, adding 100% and 50% PG significantly increased the compressive strength of the cement in comparison with control group (P=0.037 and, P=0.005, respectively). Conclusion: Considering the limitations of the present study, appropriate concentration of PG could improve the CS of MTA and CEM cement.Keywords: Calcium-Enriched Mixture Cement; Compressive Strength; Mineral Trioxide Aggregate; Propylene Glyco

Antimicrobial Efficacy and Cytocompatibility of Calcium Hypochlorite Solution as a Root Canal Irrigant: An in Vitro Investigation

Introduction: The purpose of this study was to compare the antimicrobial efficacy of sodium hypochlorite (SH) and calcium hypochlorite (CH) against Enterococcus faecalis (E. faecalis) using quantitative real-time polymerase chain reaction (qPCR) analysis and also to compare their cytocompatibility on L929 murine fibroblasts using Mossman’s tetrazolium toxicity (MTT) assay. Methods and Materials: A broth micro-dilution susceptibility test was used to determine the minimum inhibitory concentration (MIC) of each irrigant against E. faecalis. Then, the root canals of 50 mature extracted human mandibular premolars were contaminated with E. faecalis and were randomly divided into three groups according to the irrigant used (n=20). Canals were irrigated with SH in group I (n=20) and CH in group II (n=20) at their obtained MIC. In group III (n=10), sterile saline was used. Microbial sampling was performed before and after biomechanical preparation. Quantitative PCR was used to quantify E. faecalis in the root canal samples. For cytocompatibility assessment, L929 murine fibroblasts were exposed to various concentrations of the irrigants. Results: Irrigation with test materials resulted in significant reduction in colony forming units (CFU) in post-instrumentation samples (with the MIC values of SH and CH against E. faecalis being 0.5% and 5%, respectively). However, the reduction in the normal saline group was not significant (P=0.203). In addition, 5% CH was more effective than 0.5% SH (P=0.006) in eliminating E. faecalis. Among the different concentrations of tested irrigants, 0.5% CH and 5% SH showed the least and the most cytotoxicity, respectively (P<0.001). The cytotoxicity of 5% CH and 0.5% SH was similar (P=0.99), and lower than 2.5% SH (P<0.001). Conclusion: CH at an MIC of 5% was effective in eliminating E. faecalis in planktonic state and also its biofilm and exhibited comparable cytocompatibility to that of 0.5% SH.Keywords: Calcium Hypochlorite; Enterococcus faecalis; Polymerase Chain Reaction; Root Canal Irrigant; Sodium Hypochlorit