Antibacterial efficacy of silver nanoparticles, sodium hypochlorite, chlorhexidine, and hypochlorous acid on dentinal surfaces infected with Enterococcus faecalis.

The purpose of this study was to evaluate the antibacterial effect of silver nanoparticles (AgNPs) against Enterococcus faecalis and compare it with different irrigation solutions. This study was performed using 64 dentin blocks. E. faecalis suspension was dispensed to each sample and incubated under anaerobic conditions at 37°C throughout 21 days. After the inoculation period, the following solutions were added to each group and kept for 5 min: Group 1, 5.25% sodium hypochlorite (NaOCl); Group 2, 2.5% NaOCl; Group 3, 1% NaOCl; Group 4, 2% chlorhexidine (CHX); Group 5, 200 ppm hypochlorous acid (HOCl); and Group 6, AgNPs. The samples of positive control were treated with sterile saline. Biofilm viability assay was performed using the LIVE/DEAD BacLight Bacterial Viability Kit. Samples were examined using confocal laser scanning microscopy, respectively. There was no significant difference between the 5.25% NaOCl, 2.5% NaOCl, and 1%NaOCl groups (p > .05). However, these groups showed statistically higher antibacterial activity than the 2% CHX, 200 ppm HOCl, and AgNP groups. Also, 2% CHX showed greater percentage of dead cells compared with the AgNP and HOCl groups. While AgNPs group showed lower dead cell rate than all NaOCl groups and 2% CHX, it caused higher dead cells than 200 ppm HOCl group. The 200 ppm HOCl group showed the lowest percentage of dead cells (p < .05) Although the antibacterial effect of AgNPs is not as high as NaOCl and CHX, it has considerable bactericidal activity against E. faecalis and can be improved by further studies. RESEARCH HIGHLIGHTS: New antimicrobial approaches for root canal irrigation. Antimicrobial effect of silver nanoparticles against E. faecalis. Elimination of the biofilm layer for the success of endodontic treatment.

Porosity analysis of four bioceramic materials used for the repair of furcation perforations via micro-computed tomography.

BACKGROUND: Porosity is a crucial parameter that affects the solubility, sealing and mechanical strength of a material. It plays a significant role in determining the success of treatment. OBJECTIVES: The present study aimed to evaluate and compare the porosity of different bioceramic-based materials, using micro-computed tomography (micro-CT). MATERIAL AND METHODS: In the study, 76 permanent lower first or second molars that had been extracted for periodontal reasons and were free of calcification, resorption, root cavities, fractures, or cracks, with discrete roots and complete root apex development were selected. In each of the 4 experimental groups, perforations were made in the furcation areas of 19 molars. Mineral trioxide aggregate (MTA) Angelus®, EndoSequence® Root Repair Material (ERRM), Biodentine™, and BioAggregate were placed on the perforated areas of the samples and scanned with a micro-CT to evaluate porosity. The pore volume and the pore percentage with regard to the closed, open and total porosity of these repair materials were calculated individually in each sample. RESULTS: While no statistically significant differences were found between group I (MTA), group III (Biodentine) and group IV (BioAggregate) when evaluating the total pore percentage (p > 0.05), the parameter in group II (ERRM) was found to be significantly lower as compared to other groups (p > 0.05). CONCLUSIONS: In comparison with the other materials used in this study, the use of ERRM may be more suitable for perforation repair.

Effects of chitosan-containing silver nanoparticles or chlorhexidine as the final irrigant on the bond strength of resin-based root canal sealers.

Background. This study evaluated the combined effects of silver nanoparticles (AgNPs) and chitosan on the dentin bond strength of resin-based root canal sealers using the push-out test and scanning electron microscopy (SEM). Methods. This in vitro study was conducted on 72 extracted mandibular premolar teeth. All the teeth were decoronated perpendicular to the long axis to leave a 13-mm root length. The root canals were prepared, and the samples were randomly divided into seven experimental groups and one control group based on final irrigation solutions. All the final irrigation procedures were performed for one minute. The root canals were dried using paper points and filled with a resin-based sealer and gutta-percha points using a lateral condensation technique. Sections measuring 2 mm in thickness were taken from the apical, middle, and coronal thirds of each root using a cutting machine. The push-out test was performed using a universal testing machine. Results. The solution of AgNPs combined with 0.4% chitosan showed higher bond strength in the coronal region than a combination with 0.2% chitosan. Samples treated with 0.4% chitosan solution exhibited a higher bond strength than the 0.2% chitosan group. There were no significant differences between chlorhexidine (CHX) solution alone and in combination with 0.2% or 0.4% chitosan solution. Conclusion. The combination of chitosan and AgNPs was as effective as CHX in improving the bond strength of resin-based sealers.

Comparative evaluation of the antifungal efficacy of sodium hypochlorite, chlorhexidine, and silver nanoparticles against Candida albicans.

Candida albicans is a microorganism that causes root canal infections. However, it cannot be eliminated with conventional irrigation solutions. Recently, silver nanoparticles (AgNPs) have become popular for their superior antimicrobial effects. The purpose of this study was to evaluate the antifungal effect of AgNPs to C. albicans comparing with 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX). Silver nanoparticles were synthesized by chemical reduction method. Minimum inhibitory concentration and minimum fungicidal concentration of AgNPs against C. albicans strain were determined according to microdilution method reported by Clinical Laboratory Standards Institute. C. albicans biofilm layer was formed on the dentin blocks for 10 days. The biofilm structure was observed by scanning electron microscopy. Statistical analysis was performed with one way analysis of variance analysis and group comparisons were performed with Tukey test. AgNPs showed the highest antifungal effect among the groups. 5.25% NaOCl showed the lowest antifungal effect among the groups. While the 2% CHX solution had a statistically lower antifungal effect than AgNPs, it was found to have a higher effect than NaOCl (p < .016). Nanoparticles present a wide research field as an alternative irrigation solution in root canal treatment. The antifungal effect of AgNPs against C. albicans was confirmed in this study. Further in vivo studies should evaluate the conditions of use and long-term prognosis of AgNPs.

Micro-CT comparative evaluation of porosity and dentin adaptation of root end filling materials applied with incremental, bulk, and ultrasonic activation techniques.

The purpose of this study is to investigate the effect of different application methods on the adaptation to dentin and porosity properties of calcium silicate based materials. This study included 72 maxillary canine teeth that had been extracted for various reasons. Following the root canal treatment, root, end resections were performed on the specimens. After the apicectomy, 3 mm deep cavities were created. All materials were mixed according to the manufacturer's instructions. Retrograde cavities were filled with RetroMTA [Group 1a-1c], Biodentine [Group 2a-2c] and BioAggregate [Group 3a-3c]. Placement techniques were applied for each material by using incremental, bulk technique and ultrasonic activation, respectively. The samples were scanned with the SkyScan 1272 µCT system. Porosity values were higher in bulk fill and incremental placement techniques than ultrasonic technique when using MTA and BioAggregate (p < 0.05), but Biodentine showed no statistically significant difference (p > 0.05) on using different placement techniques. The ultrasonic activation technique is beneficial to improve the condensation quality of MTA and BioAggregate. Biodentine showed better results regardless of different application techniques.

Micro-CT evaluation of 'danger zone' and microcrack formation in mesial root canals of primary teeth with single-file rotary and reciprocating systems.

BACKGROUND: Although single-file rotary systems are accepted in the field of paediatric dentistry in terms of providing time advantage, research works continue due to the variable anatomical structure of the root canal. AIM: This study aimed to evaluate rotary systems in different kinematics in terms of microcracks and the shaping of the danger zone in primary molars by micro-CT. DESIGN: The mesial canals of primary molars (n = 30) were used. Root canals in each group (n = 10) were prepared with single-file rotary systems (One Shape®, OS; XP-endo® Shaper, XP-ES; WaveOne Gold, WOG). The images were evaluated for dentin thickness in the danger zone and microcrack formation. RESULTS: WOG caused the highest dentin reduction in the danger zone area. OS led to significantly less dentin reduction than XP-ES and WOG (P < .05). The XP-ES showed the highest number of microcracks (P < .05). No statistically significant difference was found between WOG and OS (P > .05). In all systems, more microcracks were observed in the middle third than coronal and apical. CONCLUSION: Within the limitations of this study, the rotary systems were superior to reciprocating in terms of shaping ability in the danger zone. It is thought that further studies with different systems should be designed considering the anatomical variations and chemical composition of primary teeth.

Silver nanoparticles in endodontics: recent developments and applications.

The elimination of endodontic biofilms and the maintenance of a leak-proof canal filling are key aspects of successful root canal treatment. Several materials have been introduced to treat endodontic disease, although treatment success is limited by the features of the biomaterials used. Silver nanoparticles (AgNPs) have been increasingly considered in dental applications, especially endodontics, due to their high antimicrobial activity. For the present study, an electronic search was conducted using MEDLINE (PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL), Google Scholar, and EMBASE. This review provides insights into the unique characteristics of AgNPs, including their chemical, physical, and antimicrobial properties; limitations; and potential uses. Various studies involving different application methods of AgNPs were carefully examined. Based on previous clinical studies, the synthesis, means of obtaining, usage conditions, and potential cytotoxicity of AgNPs were evaluated. The findings indicate that AgNPs are effective antimicrobial agents for the elimination of endodontic biofilms.

Comparative evaluation of dentin volume removal and centralization of the root canal after shaping with the ProTaper Universal, ProTaper Gold, and One-Curve instruments using micro-CT.

Background. The main goal of our study was to assess the volume of dentin removed and transportation in root canals using ProTaper Universal (PTU), ProTaper Gold (PTG) and One-Curve (OC). Ni-Ti rotary instruments in extracted human teeth using by micro-CT. Methods: Thirty human upper 1st premolar teeth with two separate root canals and sturdy, mature root tips were used in the present study. Specimens were decoronated and root length was standardized for micro CT scanning before root canal preparation done. The teeth were randomly separated into three categories (n = 10) according to the rotary NiTi system used for canal instrumentation, i.e., PTU (Dentsply, Maillefer), PTG (Dentsply, Maillefer), and OC (Micro-Mega SA). After root canal preparation, samples were scanned again on micro-CT by the same scanning parameters. Surface area, canal volume, structure model index (SMI), percentage of uninstrumented area and transportation parameters were obtained for each sample before and after micro-CT analyse. Results: No significant differences between the PTG and PTU in terms of the total volume of removed dentin, surface area and percentage of uninstrumented areas were found. However, regarding to parameters above, OC showed a lower efficacy than PTG and PTU in coronal section. Regarding canal transportation, PTG and OC showed lower mean transportation values at all levels. Conclusion: This paper demonstrated the root canal shaping abilities of the PTU, PTG, and OC NiTi file systems. The PTG and OC systems were associated less canal transportation and a better ability to preserve dentinal walls than PTU. There was no significance different between all rotary file systems for SMI values however, PTU and PTG showed greater canal volume and surface area change than OC file systems in coronal section.