The effect of nanobased irrigants on the root canal dentin microhardness: an ex-vivo study.

BACKGROUND: Given the favorable antimicrobial properties of zinc oxide (ZnONPs), standard silver (AgNPs), and imidazolium-based silver (Im-AgNPs) nanoparticles, this study aimed to evaluate their influence on the microhardness of root canal dentin. METHODS: In this experimental study, 40 mandibular premolars were decoronated at the cementoenamel junction and longitudinally sectioned into halves to create 80 specimens. They were randomly allocated to 5 groups (n = 16) and irrigated with ZnONPs, AgNPs, Im-AgNPs, NaOCl, or normal saline (as the negative control) for 15 min. The Vickers Hardness Number (VHN) was measured on each root canal third before and after being soaked in irrigants. Statistical analysis was performed using paired t-test, one-way ANOVA, and post hoc Tukey's test (α = 0.05). RESULTS: Im-AgNPs and ZnONPs irrigants improved the microhardness of root dentin, whereas, AgNPs and NaOCl decreased it. ZnONPs yielded the highest VHN at the coronal third (P˂0.001), while the Im-AgNPs provided the highest VHN at the middle and apical thirds (P˂0.001). The AgNPs group showed the lowest VHN at the apical third. CONCLUSIONS: The irrigants containing Im-AgNPs and ZnONPs significantly enhanced the root dentin microhardness. However, the use of AgNPs resulted in decreased microhardness.

The antimicrobial efficacy of nanographene oxide and double antibiotic paste per se and in combination: part II.

BACKGROUND: Finding strategies to overcome the rising trends of antimicrobial resistance against currently available antimicrobial agents has become increasingly relevant. Graphene oxide has recently emerged as a promising material due to its outstanding physicochemical and biological properties. This study aimed to validate previous data on the antibacterial activity of nanographene oxide (nGO), double antibiotic paste (DAP), and their combination (nGO-DAP). METHODS: The antibacterial evaluation was performed against a wide range of microbial pathogens. Synthesis of nGO was achieved using a modified Hummers' method, and loading it with ciprofloxacin and metronidazole resulted in nGO-DAP. The microdilution method was utilized to assess the antimicrobial efficacy of nGO, DAP, and nGO-DAP against two gram-positive bacteria (S. aureus and E. faecalis), two gram-negative bacteria (E. coli, and S. typhi), and an opportunistic pathogenic yeast (C. albicans). Statistical analysis was conducted using one-sample t-test and one-way ANOVA (α = 0.05). RESULTS: All three antimicrobial agents significantly increased the killing percent of microbial pathogens compared to the control group (P < 0.05). Furthermore, the synthesized nGO-DAP exhibited higher antimicrobial activity than nGO and DAP per se. CONCLUSION: The novel synthesized nGO-DAP can be used as an effective antimicrobial nanomaterial for use in dental, biomedical, and pharmaceutical fields against a range of microbial pathogens, including gram-negative and gram-positive bacteria, as well as yeasts.

The antimicrobial efficacy of graphene oxide, double antibiotic paste, and their combination against Enterococcus faecalis in the root canal treatment.

BACKGROUND: Inter-appointment medication of the root canals with appropriate intracanal medicaments has been advocated to improve root canal disinfection. Graphene oxide (GO) has shown promising antimicrobial activity against a wide range of microorganisms, besides the capability of carrying antibiotics. The current study aimed to compare the antibacterial activity of double antibiotic paste (DAP) and GO per se and in combination (GO-DAP) against Enterococcus faecalis (E. faecalis). METHODS: A total of 108 extracted human mandibular premolars were contaminated with three-week-old E. faecalis and subjected to a primary microbial assessment. The samples were categorized into 15 groups concerning the intracanal medicament (DAP, GO, GO-DAP, and control) and contact time (1, 7, and 14 days). Then, the root canals were medicated, incubated, and resubjected to a secondary antimicrobial evaluation. The colony-forming units (CFU) were counted to calculate the antimicrobial efficacy. The data were analyzed via the Kruskal-Wallis test (α = 0.05). RESULTS: GO-DAP was the only medicament that completely eradicated E. faecalis in 1 day. The percentage reduction of CFU/ml in the GO-DAP and DAP groups was higher than that in the GO group at all allocated contact times. Furthermore, a significant decrease of the CFU/ml was seen in the GO and DAP groups after 7 and 14 days of being medicated (P < 0.05). CONCLUSION: Since GO-DAP improved root canal disinfection, this novel material can be introduced as a promising intracanal medicament against E. faecalis even in the short run.

Mathematical validation of measurement of root fracture resistance: an in vitro study.

BACKGROUND: The aim of this study was to develop a mathematically valid method of assessing fracture resistance of roots. The model developed used mesial roots of lower molars instrumented using stainless steel hand files (SS) and two rotary nickel-titanium (NiTi) systems. METHODS: Eighty human lower molars were selected and randomly divided into four groups (n = 20). After instrumentation, the root canals were obturated using thermoplasticized gutta percha. The roots were covered with a simulated periodontal ligament and mounted vertically in autopolymerizing acrylic in PVC tubes. Using a universal testing machine, the force to fracture (N) was applied and the maximum load (FL) was recorded. Remaining dentine volume was calculated and the fracture resistance (FR) was recorded. The data were analyzed using SPSS version 22 with P < .05. RESULTS: There were no significant differences among the instrumentation methods for FL but in FR the roots instrumented using rotary NiTi showed significantly lower values than control groups and SS files (P < 0.001). CONCLUSIONS: Considering the effect of root length, volume of the root, and volume of the instrumented canal as well as the maximum failure load may be a more objective method of reporting fracture resistance of roots.

A Comparison of the Apical Extrusion of Debris during the Preparation of Root Canal with Medin, RaCe, and ProTaper Rotary Systems.

STATEMENT OF THE PROBLEM: The extrusion of intracanal debris is one of the challenging problems related to almost all root canal preparation systems, which may cause flare-ups and impairment in the healing process. PURPOSE: This study was conducted to evaluate the amount of apically-extruded debris during root canal preparation using Medin (MEDIN Co., Czech Republic) rotary system compared with two common rotary systems, including ProTaper (Dentsply Maillefer., Switzerland) and RaCe (FKG Dentaire, Switzerland). MATERIALS AND METHOD: In this in vitro study, Sixty mandibular premolars with single canal were randomly assigned to three groups (n=20). The root canals were prepared with Medin, ProTaper, and RaCe rotary instruments based on their manufacturers' instructions. The debris were collected into pre-weighted Eppendorf tubes. The weight of the extruded debris was calculated by subtracting the pretreatment weight of the vials. Data were analyzed using the Kruskal-Wallis test at a 5% significance level. RESULTS: Medin instrument caused significantly less debris extrusion in comparison with ProTaper and RaCe (p< 0.05). The differences between the ProTaper and RaCe rotary systems were not statistically significant (p= 0.752). CONCLUSION: Within the limitations of this in vitro study, Medin rotary system produced less apical extrusion than ProTaper and RaCe.

Demographic Evaluation of Oro-Dental Self-Injury for Insurance Deception; Evaluation of the Cases Referred to Shiraz Forensic Medicine Center.

STATEMENT OF THE PROBLEM: Nonsuicidal self-inflicted injuries are socially unacceptable and may cause mild to severe damages. PURPOSE: This study aimed to evaluate the demographic features of the subjects with orodental self-injuries referred to a forensic medicine center in Shiraz, Iran. MATERIALS AND METHOD: This cross-sectional study evaluated 51 participants (49 men and 2 women) with orodental injuries referred to forensic medicine administration. Orodental self-injury was detected in the subjects, based on the last forensic criterion of self-injuries, considering their history, clinical examinations, and panoramic radiographs. RESULTS: The findings of this study revealed that dental self-injuries were more prevalent among married men from urban areas with secondary education levels. Most of the cases were due to the monetary compensation received. In the majority of cases, a hard object was used for this self-injury. Moreover, no statistical association was observed between the economic status and orodental self-injury. CONCLUSION: This study concluded that dental self-injury could be regarded as an unplanned incident because no significant correlation was observed between the participants, their economic status, and the type of dental trauma. Furthermore, detailed investigations on the latent variables are required.

Assessment of tooth discoloration induced by biodentine and white mineral trioxide aggregate in the presence of blood.

INTRODUCTION: In clinical dental application, using silicate-based cements is extremely popular. These materials come into direct contact with blood during or after placement and may cause tooth discoloration. OBJECTIVES: The purpose of this study was to compare the coronal tooth discoloration induced by white mineral trioxide aggregate (MTA) and biodentine in the presence of blood. MATERIALS AND METHODS: Seventy specimens were chemomechanically prepared and divided into four experimental and two control groups. In the experimental groups, the pulp chambers were filled with white MTA angelus or biodentine. Blood or saline saturated cotton pellets were placed within the canals. Saline or blood alone was used in the control groups. Color was assessed with a spectrophotometer at baseline, 1 week, and 1 and 3 months, and color change values were calculated. Tukey's honestly significant difference and Sidak tests were used for statistical analysis. RESULTS: The color change was significantly less with biodentine/saline than MTA/saline and MTA/blood (P < 0.05). Regardless of the material type and blood presence, discoloration increased after 3 months (P < 0.05). CONCLUSION: Discoloration induced by biodentine/saline may not be clinically noticeable and it was less than MTA-containing groups. Irrespective of blood presence or absence, MTA caused perceptible color change.

Effect of a New Imidazolium-based Silver Nanoparticle Irrigant on the Bond Strength of Epoxy Resin Sealer to Root Canal Dentine.

Introduction: The aim of this study was to evaluate the effect of a new imidazolium-based silver nanoparticle (ImSNP) root canal irrigant on the bond strength of AH-Plus sealer to root canal dentine. Methods and Materials: Forty single-rooted extracted human teeth were used in this study. The crowns were resected and according to the irrigation solutions used during root canal preparation, the roots were divided into 5 groups (n=8): Group 1: normal saline (control group), Group 2: 2.5% Sodium Hypochlorite (NaOCl), Group 3: 2.5% NaOCl+17% ethylene diamin tetracetic acid (EDTA), Group 4: silver nanoparticles (AgNPs), Group 5: AgNPs +17% EDTA. After root canal instrumentation, the canals were filled with AH-Plus. Then, after 7 days, 2 or 3 dentine disks were obtained from the mid-root of each sample. Bond strength was measured by the push-out test. Additionally, failure patterns were classified as adhesive, cohesive and mixed. Data were statistically analyzed by one-way ANOVA and Tamhane post hoc tests. The level of significance was set at 0.05. Results: There was no statistically significant differences between groups (P>0.05). Groups 4 (AgNPs), 3 (2.5% NaOCl+17% EDTA) and 2 (2.5% NaOCl) showed statistically higher bond strength compared to group 1 (control group) (P<0.05). Also, Group 4 showed a significant difference with group 5 (AgNPs+17% EDTA) (P=0.017). The failure patterns were mainly cohesive. Conclusion: This in vitro study showed that, when used without EDTA, AgNPs improved the bond strength of AH-Plus to radicular dentine.

In Vitro Evaluation of Dynamic Viscosity, Surface Tension and Dentin Wettability of Silver Nanoparticles as an Irrigation Solution.

Introduction: The aim of this study was to evaluate dynamic viscosity, surface tension and dentin wettability of a newly introduced imidazolium-based silver nanoparticle solution (Im AgNP) in comparison with three common root canal irrigants. Methods and Materials: The irrigants were Im AgNPs at 5.7×10-8 mol/L-1, 5.25% Sodium hypochlorite (NaOCl), 2% Chlorhexidine (CHX) and 17% Ethylenediaminetetraacetic acid (EDTA) and distilled water (control group). Dynamic viscosity was measured using rotational digital viscometer at 25, 37, 45 and 60°C. Surface tension was evaluated using dynamic contact angle analyzer at room temperature (25°C). Wettability was assessed by contact angle measurement for five groups of 10 dentin samples after each group was treated in each irrigant for 10 min. One-way ANOVA, and post hoc Tukey's test were used for statistical analysis. Significance was set at P<0.05. Results: Dynamic viscosity of all irrigants decreased as the temperature increased. 17% EDTA was the most viscous solution in all examined temperatures (P<0.05). Viscosity of Im AgNP solution at 25, 37 and 45°C was significantly lower than that of 17% EDTA and 5.25% NaOCl (P<0.05). Im AgNPs exhibited a higher surface tension than other irrigants except distilled water. The wettability of dentin increased when it was in contact with 2% CHX and 5.25% NaOCl while Im AgNPs decreased the wettability of dentin surfaces (P<0.05). Conclusion: Im AgNP irrigant has the potential to reach apical portions of root canals due to its lower viscosity compared to the other tested irrigants. However, it may not bring better penetration inside dentinal tubules because of its higher surface tension. Furthermore, Im AgNPs can influence physiochemical properties of dentin by decreasing its surface wettability.

In Vivo Biocompatibility of an Ionic Liquid-protected Silver Nanoparticle Solution as Root Canal Irrigant.

INTRODUCTION: The aim of this study was to assess the biocompatibility of positively charged imidazolium-based ionic liquid-protected nanosilver solution (AgNPs) root canal irrigant. METHODS AND MATERIALS: Eighteen male 4- to 5-month old Sprague-Dawley rats, weighing 200-300 gr were selected and randomly divided into 5 groups: Normal saline 0.9% (group 1), 5.25% NaOCl (group 2), 2.5% NaOCl (group 3), 2.0% chlorhexidine solution (group 4) and AgNPs at 5.7×10-8 M/L (group 5) were randomly injected in 5 sites of dorsal skin of each rat. Tissue inflammatory reaction were evaluated histopathologically after 2 h, 48 h and 14 days. Statistical analysis was done with SPSS version 21 and the Kruskal-Wallis H and Dunn tests were used to find statistically significant differences. The level of significance was set at 0.05. RESULT: All solutions irritated the highest tissue response after 48 h. Group 1 showed lower inflammatory response compared to groups 2 and 4 (P<0.05). Group 2 displayed higher inflammatory response in comparison with group 5 (P<0.05). Tissue reaction to group 5 was not more severe than the reaction to group 3 or 4. It also would irritate less inflammatory response compared to group 2 (P<0.05). CONCLUSION: Comparing with NaOCl and CHX, it is possible to label AgNPs as a tissue compatible agent.

Efficiency of Castor Oil as a Storage Medium for Avulsed Teeth in Maintaining the Viability of Periodontal Ligament Cells.

STATEMENT OF THE PROBLEM: Researchers always seek a new storage medium for avulsed teeth. Castor oil is a vegetable oil with several advantages such as antimicrobial and antioxidant properties, low toxicity, and glutathione preservation capability, low cost, and high availability. PURPOSE: The purpose of this study was to evaluate and compare the capacity of castor oil as a new storage medium in preserving the viability of periodontal ligament (PDL) cells compared to Hank's balanced salt solution (HBSS) and milk. MATERIALS AND METHOD: Forty freshly extracted human teeth were divided into 3 experimental and 2 control groups. The experimental teeth were stored dry for 30 min and then immersed for 45 min in one of the following media; castor oil, HBSS, and milk. The positive and negative control groups were exposed to 0 min and 2 h of dry time respectively with no immersion in any storage medium. The teeth were then treated with dispase grade II and collagenase and the number of viable PDL cells were counted. Data were analyzed using Kruskal- Wallis test. RESULTS: The percentage of viable cells treated with castor oil, HBSS and milk counted immediately after removal from these media were 46.93, 51.02 and 55.10 % respectively. The statistical analysis revealed that the value for castor oil was significantly lower than HBSS and milk (p> 0.05). CONCLUSION: Within the parameters of this study, it appears that castor oil cannot be served as an ideal medium for storage of avulsed tooth. More investigations under in vivo conditions are required to justify the results of this study.

Evaluation of the wettability of a resin-based sealer in contact with some herbal irrigants.

BACKGROUND: An ideal root canal irrigant should be able to enhance the wettability of sealer to dentin walls. The aim of this study was to survey the contact angle between AH 26 sealer and dentin surface irrigated by four herbal essential oils, compared with normal saline and 5.25% sodium hypochlorite (NaOCl). MATERIALS AND METHODS: In this in vitro study, 60 longitudinal dentin slices were obtained from thirty extracted single-rooted human mandibular first premolars. After smear layer removal, the samples were divided into six groups of 10 samples and irrigated for 1 min with the experimental solutions followed by distilled water: G1: Myrtus communis, G2: Cinnamomum zeylanicum, G3: Zataria multiflora (ZM), G4: Cuminum cyminum (CC), G5: normal saline, and G6: NaOCl 5.25%. The contact angle between AH 26 and the samples was measured using Motic Images Plus 2.0 software. Data were analyzed statistically using one-way analysis of variance (P < 0.05 consider significant). RESULTS: All the herbal irrigants, except CC, increased the contact angle of AH 26 sealer (P ≤ 0.05). The least value of contact angle was seen in the samples treated with CC, and the maximum value was observed in samples treated with ZM. 5.25% NaOCl showed a slightly increased contact angle compared to normal saline; however, it was not statistically significant (P > 0.05). CONCLUSION: Under the experimental condition of this study, CC was able to increase dentin wettability and therefore may be regarded as a promising irrigant after careful evaluation of other properties of this irrigant.

Effect of Endodontic Irrigants and Medicaments Mixed with Silver Nanoparticles against Biofilm Formation of Enterococcus faecalis.

Introduction: The aim of this study was to evaluate the effectiveness of chlorhexidine (CHX), sodium hypochlorite (NaOCl), calcium hydroxide (CH) and double antibiotic paste (DAP) mixed with silver nanoparticles (AgNPs) against Enterococcus faecalis . Methods and materials: Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and biofilm formation inhibition (after 72 h) of the experimental substances alone or mixed with AgNPs were measured against E. faecalis using microtiter plate method. Bacterial cultures turbidity was measured using a spectrophotometer. All procedures were performed in triplicates. Results: The MIC values for CHX, NaOCl, CH and DAP were equal to 0.012, 1.25, 1.6 and 0.156 mg/mL, and their MBC's were 0.025, 2.5, 0 and 0.625 mg/mL. After mixing them with AgNPs, the MIC's for CHX, NaOCl, CH and DAP were reduced to 0.0032, 0.158, 0.2 and 0.0391 mg/mL, while their MBC's were reduced to 0.0064, 0.0632, 0.401 and 0.0156 mg/mL. Biofilm formation inhibition occurred in higher dilutions of all irrigants and medicaments as they were mixed with Ag NPs. Conclusions: Adding AgNPs resulted in an increased antimicrobial activity at the tested dilutions for all experimental substances. More investigations in in vivo conditions are required to confirm the results of this study.

Cone-Beam Computed Tomographic Evaluation of Radicular Grooves in Maxillary Anterior Teeth in a Selected Iranian Population.

Introduction: The region of maxillary anterior teeth is susceptible to numerous anomalies such as radicular groove (RG). RG usually begins by the cingulum of the tooth and proceeds to the root surface in various lengths and depths. This anomaly can prone the tooth to periodontal and endodontic pathosis. The aim of this study was to evaluate the prevalence of RG in maxillary anterior teeth in an Iranian population using cone-beam computed tomography (CBCT). Methods and Materials: A total of 552 CBCT images of maxillary anterior teeth were randomly selected from the archive of a radiology clinic in Shiraz, Iran. Eighteen hundred maxillary anterior teeth met the inclusion criteria. The variants including patient's gender, tooth type, presence or absence and unilateral or bilateral incidence of RGs, their types, and mesiodistal location of RGs were analyzed using the Chi-square test. Results: RGs were diagnosed in 0.5% of central incisors, 2.6% in lateral incisors and 0.16% in canines. The prevalence of RGs in maxillary incisors and maxillary anterior teeth were calculated 1.58% and 1.11%. Statistical analysis showed that there was no significant relationship between gender and the presence, symmetry and location of RGs, but different tooth types had significant differences in the presence of RGs. Conclusion: In this cross sectional study the prevalence of RG had higher frequency in lateral incisors in comparison with canines and central incisors. CBCT is very useful in RG cases and is beneficial in RG diagnosis and treatment planning.

The Effects of Different Ionic Liquid Coatings and the Length of Alkyl Chain on Antimicrobial and Cytotoxic Properties of Silver Nanoparticles.

INTRODUCTION: The antibacterial efficacy and toxicity of silver nanoparticles (AgNPs) depends on their physicochemical properties including size, shape, surface charge and surface coatings. The Objectives of this study were: i) To synthesize and characterize positively charged AgNPs coated by different ionic-liquids with different alkyl chain lengths, ii) To evaluate the antimicrobial activity of these nanoparticles against Enterococcus faecalis compared to sodium hypochlorite (NaOCl) and chlorhexidine (CHX), iii) To compare the cytocompatibility of these solutions against L929 mouse fibroblasts. METHODS AND MATERIALS: AgNPs with positive surface charges capped by two different ionic liquids [imidazolium (Im) and pyridinium (Py)] with two alkyl chain lengths (C12 and C18) were synthesized. Im and Py were also tested as control groups. The characterization revealed synthesis of spherical NPs in the size range of 6.7-18.5 nm with a surface charge ranging from +25 to +58 mV. To standardize the comparisons, the surface charge to radius ratio of each nanoparticle was calculated. The minimum inhibitory concentrations (MIC) of the AgNP solutions, NaOCl and CHX were determined against E. faecalis by a microdilution test. An MTT-based cytotoxicity assay evaluated the cytotoxicity of the solutions in different concentrations on L929 fibroblasts. One-way and two-way ANOVA were used for statistical analysis. RESULTS: All tested AgNPs reached MIC90 in significantly lower concentrations compared to CHX and NaOCl. C12 Py-coated AgNPs had the lowest MIC90 value. CHX and NaOCl were more toxic on fibroblasts than all tested AgNPs. Im-coated AgNPs had better compatibility with fibroblasts than Py-coated particles; and C12 Im AgNPs had the best biocompatibility. Variations in alkyl chain length had no effects on the biocompatibility of AgNPs. CONCLUSION: Py improved the antibacterial efficacy of AgNPs compared to Im; however, it had a negative effect on cytocompatibility. Alkyl chain length had no effects on AgNPs' bioactivity.

The Effect of Calcium Chloride on Push-Out Bond Strength of Calcium-Enriched Mixture Cement and Mineral Trioxide Aggregate.

INTRODUCTION: This in vitro study investigated the effect of adding 10% calcium chloride (CaCl2) on push out bond strength of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA) to root canal dentin. METHODS AND MATERIALS: A total of 120 root dentin slices with 2 mm thickness were prepared from sixty single-rooted human teeth. Dentinal discs were enlarged to achieve 1.3 mm diameter. The specimens were randomly allocated into eight groups (n=15). Dentin discs were filled with either CEM cement or MTA with or without CaCl2 and the push out test was performed after 3 and 21 days. Data were analyzed with two-way ANOVA test. The level of significance was set at 0.05. RESULTS: There was an interaction effect amongst all groups (P=0.028). After 3 days, CEM cement showed a significantly lower bond strength than other groups (P<0.05) while MTA demonstrated significantly higher bond strength than CEM cement with or without CaCl2 (P=0.001). After 21 days, CEM cement with or without CaCl2 had no significant difference with other groups (P>0.05). However, the bond strength of MTA decreased when CaCl2 was added (P=0.011). CONCLUSION: The addition of 10% CaCl2 increased the push out bond strength of CEM cement and improved it over time; while, this substance aggravated this property for MTA.

Effect of Imidazolium-Based Silver Nanoparticles on Root Dentin Roughness in Comparison with Three Common Root Canal Irrigants.

INTRODUCTION: The aim of this study was to evaluate the effect of a nanosilver-based irrigant on dentin roughness in comparison with three commonly used root canal irrigation solutions. METHODS AND MATERIALS: Three common irrigants including 5.25% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA) and 2% chlorhexidine (CHX) and also an imidazolium-based silver nanoparticle solution (ImSNP) (5.7×10 -8 mol/L), were used. Distilled water was used as control. Roots of 25 human anterior teeth were sectioned longitudinally to obtain 50 dentin samples. Roughness values were evaluated by atomic force microscopy analysis on 5 groups (n=10) after each group was treated in one of the tested irrigant solutions for 10 min. Values were statistically analyzed by One-way analysis of variance, followed by a post hoc Tukey's test for pair-wise comparison. RESULTS: Dentin roughness significantly increased from 95.82 nm (control) to 136.02 nm, 187.07 nm, 142.29 nm and 150.92 nm with NaOCl, CHX, ImSNP and EDTA, respectively. CHX demonstrated a significantly higher roughness value compared to the other tested irrigants while no significant differences were seen in NaOCl, ImSNP and EDTA groups (P>0.242). CONCLUSION: ImSNP affected the physicochemical properties of dentin and raised its surface roughness; thus, this irrigant could impact bacterial and restorative material adhesion to root canal dentin walls.

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.

Antimicrobial and Cytotoxic Activity of Cinnamomum zeylanicum, Calcium Hydroxide, and Triple Antibiotic Paste as Root Canal Dressing Materials.

OBJECTIVE: The aim of this article was (i) to define the chemical constituents of Cinnamomum zeylanicum essential oil (CEO), (ii) to compare the antimicrobial activity of CEO with triple antibiotic paste (TAP) and calcium hydroxide [Ca(OH)2] on planktonic and biofilm Enterococcus faecalis; and (iii) to compare the cytotoxicity of these medicaments on L929 fibroblasts. MATERIALS AND METHODS: Gas chromatography-mass spectrometry was used to define the constituents of CEO. Zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill tests were performed. Further, 108 human teeth were infected with E. faecalis and treated with the medicaments for 1, 7, and 14 days. Cytotoxicity was assessed by exposing L929 fibroblasts to the medicaments. RESULTS: Cinnamaldehyde was the main component of CEO. Triple antibiotic paste had the greatest zone of inhibition and the smallest MIC and MBC. Triple antibiotic paste and CEO eradicated planktonic E. faecalis after 4 and 24 hours, while Ca(OH)2 failed to achieve 100% killing after 24 hours. Cinnamomum zeylanicum essential oil and TAP eradicated biofilm E. faecalis after 7 and 14 days, but Ca(OH)2 could not eliminate E. faecalis after 14 days. Cinnamomum zeylanicum essential oil was the most biocompatible medicament. CONCLUSION: Cinnamomum zeylanicum essential oil is an efficient antibacterial agent against planktonic and biofilm E. faecalis and it was cytocompatible to L929 fibroblasts. Therefore, CEO has the potential to be used as an antimicrobial agent in root canal treatment.

In vitro comparison of antimicrobial effect of sodium hypochlorite solution and Zataria multiflora essential oil as irrigants in root canals contaminated with Candida albicans.

INTRODUCTION: This study compared the antifungal effect of Zataria multiflora essential oil (EO) with that of sodium hypochlorite (NaOCl) as an irrigant for root canals infected with Candida albicans. MATERIALS AND METHODS: Sixty mandibular premolars were infected with C. albicans suspension. After 72 h of incubation, the samples were divided into four groups. Teeth in Group 1 were irrigated with minimum fungicidal concentration (MFC) of Z. multiflora EO, in Group 2 with twice the MFC of Z. multiflora, in Group 3 with MFC of NaOCl, and in Group 4 with distilled water (DW). Pre- and post-operative samples were cultured, and fungal colony count of each specimen was obtained. Data were analyzed using Kruskal-Wallis and Mann-Whitney tests (P < 0.05). RESULTS: NaOCl at MFC and Z. multiflora EO at twice the MFC showed the highest antifungal efficacy, with no significant difference (P > 0.05). However, antifungal efficacies of these irrigants were significantly different from those of Z. multiflora EO at MFC and DW (P < 0.05). CONCLUSION: Our results showed that Z. multiflora EO at twice the MFC had the same antifungal efficacy as NaOCl at MFC.