Root Dentine Strain Generation during Root Canal Instrumentation with Rotation and Reciprocation Motions

The aim of the study is to measure and compare strain generated on root dentine surface by two different instrumentation motions. Thirty extracted single canal premolars were used in this study which randomly was divided into two groups, one group was prepared with ProTaper NEXT X2 file in rotation motion, and the second group was prepared by WaveOne GOLD primary file in reciprocation motion, the canals were irrigated during canal preparation by 2 ml of sodium hypochlorite and 17% EDTA gel was used. Strain measurement was performed by strain gauges and a digital strain output reader, data were recorded every 5 s for 50 s. The results of this study have shown that WaveOne GOLD had higher mean 0.7308±0.41106 than ProTaper next 0.5385±0.39904 which means WaveOne GOLD generates greater strain than ProTaper NEXT. However, according to Student’s t-test between two groups there is no statistical difference between them. Based on the results of this study, there was no difference between the two motions; both motions generated strain on root dentine surface.

The Antibacterial Effects of Quaternary Ammonium Salts in the Simulated Presence of Inhibitors in Root Canals: A Preliminary In-Vitro Study

To investigate the antibacterial effects of two newly developed quaternary ammonium salts (QAMs)-dimethylaminododecyl methacrylate (DMADDM) and dimethylaminohexadecyl methacrylate (DMAHDM), in the presence of various root canal inhibitors. Streptococcus gordonii, Enterococcus faecalis, Lactobacillus acidophilus and Actinomyces naeslundii were used. Dentine, dentine matrix and dead bacteria were selected as inhibitors. The antimicrobial efficacy of monomers of DMADDM and DMAHDM was tested against suspensions formed by mixtures of four bacterial species in or without the presence of inhibitors. The inhibition results were compared with chlorhexidine (CHX) and sodium hypochlorite (NaOCl). One-way analyses of variance (ANOVA) followed by Tukey’s multiple comparison test was performed to determine significant differences. The antibacterial effects of DMADDM and DMAHDM were variably inhibited dentine, dentine matrix and dead bacteria. CHX and NaOCl showed substantivity and they inhibited bacteria present in suspension. The concentration of compound decreased in the dentine block due to constant release. Bacterial colonies on the dentine surface and dentine tubules were significantly inhibited by DMADDM and DMAHDM. The antibacterial effects of DMADDM and DMAHDM could be inactivated by dentine, dentine matrix and dead bacteria, while DMADDM and DMAHDM could inhibit bacteria colonization on the dentine surface and kill bacteria present in dentinal tubules. The antibacterial effects of DMADDM and DMAHDM as free monomers in the presence of inhibitors was evaluated for the first time. They could help inhibit the residual bacteria on the dentine surface and in dentinal tubules that may cause persisting infection. Therefore the novel QAMs showed great potentials as root canal medication.

COMPARATIVE QUALITY ASSESSMENT OF ROOT CANAL PREPARATION WITH DIFFERENT SYSTEMS OF ENDODONTIC INSTRUMENTS

The aim: To compare the quality of root canal system preparation with the use of manual K-files, machine Protaper Universal and Silk files by in vitro studies. Materials and methods: Root canals preparation in 45 extracted premolars was performed in three groups with 15 teeth in each with K-files, Protaper Universal and Silk files. Transverse sections of the dental root were prepared. Histologically were assessed: amount of sawdust and predentin remaining, the purity degree of root canal walls. Results: When calculating the sawdust amount at the distance of 3 mm from an apex, a high degree of contamination was observed in the manual K-file group: 53.3% versus 33.3% in the Protaper Universal group and against 20.0% in the Silk file group. The amount of predentin after root canal treatment with manual files reached 25-30%. At the distance of 5 mm from the apex the root canals with high and medium purity degree were detected in 86.7% with Silk files and 80.0% with Protaper Universal files used. All predentin was removed when working with Protaper Universal and Silk files. Conclusions: In the histological sections of the root canals treated with K-files, the larger amount of dentine particles and predentin has been revealed than when using machine tools. The largest amount of predentin and dentine were removed with Protaper Universal files. Silk endodontic system is better for treatment of the root canals dentine surface in the apical area compared to Protaper Universal and K-files.

TENSILE STRENGTH OF BONDING MATERIAL TO DENTINE USING WATER-WET AND ETHANOL-WET TECHNIQUES

Background: Composite resins have hydrophobic properties so it cannot attach to dentine. Moist dentin is a normal condition caused by the presence of fluid in dentinal tubules. Therefore bonding material is required to bond dentine with composite. Water-wet technique is a technique in which dentine surface is rinsed after etching by using water and allowing it to be moist and prevent the collapse of dentine collagen fibrils. This technique is commonly used today, but excess water disturbs the effectiveness of dentine and bonding material attachment. Ethanol-wet technique is a technique in which ethanol is used to replace water before bonding to reduce excess water in dentine surface. This technique will initiate monomer penetration into interfibrillar space of dentine. It will affect the result of tensile strength test. Purpose: The purpose of this study was to compare tensile strength of bonding material to dentine using water-wet and ethanol-wet techniques. Method: 12 samples of bovine incisors teeth were randomly divided into 2 group. Each group consists of six samples. Group 1 was treated with water-wet technique and group 2 was treated with ethanol-wet technique. Autograph was used as a tensile strength test instrument. Result : The average of tensile strength using water-wet technique was 2,16067 MPa and ethanol-wet technique was 4,21900 MPa. Conclusion: Ethanol-wet technique have higher value of tensile strength than water-wet technique.

A comparative study of the microtensile bond strength and microstructural differences between sclerotic and Normal dentine after surface pretreatment

Background The resin bond strength of sclerotic dentine is significantly lower than that of the normal dentine, which paused a challenge for bonding procedures clinically. The aim of this study was to compare the effects of different surface pretreatments on the micro-tensile bond strength and microstructure between sclerotic dentine and normal dentine. Methods Eighty teeth that were collected, forty premolars with typical wedge-shaped defects visually graded as class III were assigned as the sclerotic dentine group (SD), the other forty normal premolars with artificial wedge-shaped defects were assigned as the normal dentine group (ND). Each group was randomly subdivided into eight subgroups according to the solution used: 35% phosphoric acid, 15% EDTA, 5% or 10% NaClO. Then the dentine surface was examined using a scanning electron microscope (SEM). The lesions were restored using self-etching adhesive and the subsequent resin composite. The teeth were sectioned into sticks for the micro-tensile bond strength analysis, and the data were analysed using the SPSS17.0 software package (α = 0.05). Results First, for the ND groups, after pretreatment using 35% phosphoric acid, and 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the normal dentine were higher than that of the other groups (P < 0.05). Second, for the SD groups, after pretreatment using 35% phosphoric acid, 15% EDTA, and 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the sclerotic dentine were higher than that of the other groups (P < 0.05). Third, the bond strengths of the sclerotic dentine were lower than that of the normal dentine without any pretreatment (P < 0.05). After pretreatment using 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the sclerotic dentine were higher than that of the normal dentine (P < 0.05). SEM observation showed that the appearances of dentine surface were changed after pretreatment using the above solutions, with the reduced smear layer, opened small groove and increased dentinal tubules. Conclusion Pretreatment of dentine using 35% phosphoric acid+ 5% or + 10% sodium hypochlorite changed the microstructure of the sclerotic dentine surface and subsequently increased the micro-tensile bond strength.

The effects of different irrigation agents on root canal dentine micro-hardness and surface roughness

Aim: Successful endodontic treatments rely on sufficient mechanical preparation and irrigation of the root canal followed by an adequate three-dimensional filling. This study investigated the changes in root dentine micro-hardness and surface roughness upon treatment with different irrigating agents. Methodology: A total of 60 human maxillary incisors and canine teeth were used in this study. The crowns of all teeth were decoronated and roots were divided longitudinally. The samples were separated into three groups prior to irrigation. A 5% NaOCl irrigation agent was applied to the first group, a QMix agent was used for the second group, and a 2% CHX agent was used for the third group. All irrigations were performed for 15 minutes. Following irrigation, microstructural and surface-roughness measurements were taken again from all samples. Results: Micro-hardness was not significantly different between QMix or 5% NaOCl (p>0.05). A significant difference was observed between the QMix- and 2% CHX-treated groups, and between the 5% NaOCl- and QMix-treated groups (p<0.05). A significant difference in surface roughness was observed between the QMix and 2% CHX, and between the 5% NaOCl and QMix (p<0.05). No difference in surface roughness was observed between 5% NaOCl or 2% CHX. The 5% NaOCl and QMix agents reduced the dentine micro-hardness equal to or more than that of the 2% CHX agent. The QMix agent also increased the dentine surface roughness significantly more than the other agents. The 5% NaOCl and 2% CHX agents increased surface roughness equally. Conclusions: It was seen that all of the irrigation agents used in our study affected dentin microhardness and surface roughness at different rates. How to cite this article: Öztekin F, Adıgüzel Ö. The effects of different irrigation agents on root canal dentine micro-hardness and surface roughness. Int Dent Res 2019;9(1):16-21. Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.