Comparative Evaluation of the Effect of Different Endodontic Irrigation Protocols on the Microhardness of Root Canal Dentin: An In Vitro Study

Aim and Objective The present in vitro study was done to comparatively evaluate the effect of different endodontic irrigation protocols on the microhardness at coronal, middle, and apical levels of root canal dentin. Method The total sample size for the study was 100. Each sample consisted of a longitudinally sectioned half of a root of a single-rooted tooth, which was then embedded in acrylic resin. The prepared samples were divided randomly into five groups of twenty samples each. Each group was treated with its respective irrigant to be tested. Group I was the control—the specimens were treated with distilled water. The specimens in group II were treated with sodium hypochlorite (NaOCl), followed by ethylenediamine tetra-acetic acid (EDTA). Specimens in group III were treated with NaOCl, followed by CHX. Specimens in group IV were treated with NaOCl, followed by hydroxyethylidene bisphosphonate (HEBP), and specimens in group V were treated with NaOCl, followed by propolis. Following this, all the samples were placed on the Vickers microhardness tester, and the results were tabulated and statistically analyzed to determine the irrigant solutions' effect on the microhardness of root dentin at coronal, middle, and apical third. Results Intergroup comparison of various irrigants showed that 18% HEBP showed the least reduction in the microhardness values of root canal dentin, and 17% EDTA caused the maximum decrease in microhardness values with a significant difference. When the baseline values were compared with the values after the use of experimental solutions in all the groups, it was observed that the microhardness gradually decreased from coronal to apical third of root dentin. Conclusion On the basis of the results obtained, it can be concluded that weak chelators such as 18% HEBP do not affect the microhardness considerably, and that they can be used in future in place of strong chelators, that is, EDTA, which make root dentin weak by more microhardness reduction.

Debris Removal by Activation of Endodontic Irrigants in Complex Root Canal Systems: A Standardized In-Vitro-Study

Aim of the study was to develop a standardized model system to investigate endodontic irrigation techniques and assess the efficiency of different activation methods on the removal of hard tissue debris in complex root canal systems. Mesial roots of mandibular molars were firstly scanned by micro-computed tomography (µCT) and allocated to three groups of irrigant activation: sonic activation (EDDY, VDW, Munich, Germany), laser activation (AutoSWEEPS, FOTONA, Ljubljana, Slovenia) and conventional needle irrigation (control). Roots were fixed in individual 3D-printed holders to facilitate root canal enlargement under constant irrigation with NaOCl (5%). To enable standardized quantification of remaining debris, BaSO4-enriched dentine powder was compacted into the canals, followed by another µCT-scan. The final irrigation was performed using 17% ethylenediaminetetraacetic acid (EDTA) and 5% sodium hypochlorite (NaOCl) with the respective activation method, and the volume of remaining artificial debris was quantified after a final µCT-scan. The newly developed model system allowed for reliable, reproducible and standardized assessment of irrigation methods. Activation of the irrigant proved to be significantly more effective than conventional needle irrigation regarding the removal of debris, which persisted particularly in the apical third of the root canal in the control group. The efficiency of irrigation was significantly enhanced with laser- and sonic-based activation, especially in the apical third.

Antimicrobial Efficacy of Silver Nanoparticles as Root Canal Irrigant’s: A Systematic Review

Removal of microbes is imperative during endodontic therapy. Due to their antimicrobial property, silver nanoparticles have been used for endodontic irrigation of the root canals. The objective of the present study was to provide a qualitative analysis of the published literature assessing silver nanoparticles as root canal irrigants. A search of PubMed, SCOPUS, Web of Science, and Embase databases was done without any time restriction. Articles published in English were included. Data were extracted and the risk of bias was assessed. Of the 154 studies identified, after screening according to the inclusion criteria, five in vitro studies were included. The results indicate that silver nanoparticles have an anti-microbial effect to varying degrees depending on certain factors. Within the limitations of the present studies that have a moderate to low risk of bias, an antimicrobial effect of silver nanoparticles is observed. Silver nanoparticles have the potential to be used as endodontic irrigants, although their efficacy depends on particle size and the duration of contact which require further investigation.

Consequences of chemical residue formation during potentiation of final irrigation

Seeking to increase the efficiency of endodontic irrigation, the association of different solutions as final irrigant has been investigated, such as sodium hypochlorite with chlorhexidine. The literature shows that the combination of these substances leads to the formation of a brownish precipitate, but does not reveal measurements of the intensity of this precipitate and its consequences. Aim: The present study aimed to evaluate the change in dentin color and the obliteration of the dentinal tubules after the association of sodium hypochlorite (NaOCl) with chlorhexidine (CHX) in the final irrigation. Methods: Fifty sterile human lower premolars were prepared with a ProDesign R 35.05 files and divided into 6 groups. Four different NaOCl concentrations (0.5%; 1%, 2.5% and 5.25%) associated with 2% CHX were tested, in addition to 2 control groups, using only 2.5% NaOCl and 2% CHX, respectively. After the final irrigation protocol, the dentin color change was evaluated by spectrophotometry immediately and after 24 hours, and the dentinal tubule obliteration was assessed by scanning electron microscopy. Results: It was possible to verify that regardless the NaOCl concentration used when associated with CHX, a chemical residue was formed, with consequent dentin pigmentation and tubular obstruction. There was a trend towards increased dentin pigmentation and tubular obstruction due to the deposition of the chemical residue formed by this association. Conclusion: It can be concluded that all concentrations of NaOCl associated with CHX caused color changes and tubular obstruction, being proportional to the concentration of NaOCl used.