Comparing post-obturation of apical microleakage following the use of different intracanal chelators

Objectives: different chelators may be used during root canal treatment, offering various advantages including lubricant effect inside the canal and smear layer removal. However, chelator residues in narrow root canals can lead to apical microleakage. The aim of this in-vitro study was to compare apical microleakage following the use of three root canal chelators via fluid filtration method in root canals instrumented with ProTaper rotary system

Methods: sixty-eight distobuccal canals of maxillary first molars were randomly divided into six groups of four experimental [n=15] and a positive and a negative control group [n=4]. In groups one to three, RC-Prep, 17% EDTA and Glyde File Prep were used as chelators, respectively and sodium hypochlorite [NaOCl] was used as irrigant in all groups except for group four. In group four, root canals were instrumented without chelators and only saline was used for irrigation. Root canals in all groups were prepared using ProTaper rotary system up to F[2] file and filled using cold lateral condensation technique with gutta-percha and AH26 sealer. Apical microleakage was assessed by fluid filtration method. The data were subjected to Kruskal-Wallis test

Results: no significant differences were noted among the experimental groups regarding apical microleakage [p>0.05]. However, preparations with RC Prep+ NaOCl and Glyde File Prep+ NaOCl yielded the highest and the lowest values of apical microleakage, respectively

Conclusion: use of different chelators did not cause statistically significant difference in apical microleakage of root canals

survey on NiTi rotary instruments usage by endodontists and general dentist in Tehran

The aim of this study was to assess the extent of adoption, application and the associated issues with the nickel-titanium [NiTi] rotary instruments and techniques amongst endodontists and general dentists in Tehran. A total of 33 questions classified in six categories of demographics, frequency rate of NiTi rotary instrumentation and information. The sample size comprised of 100 endodontists and 100 general dental practitioners in Tehran. The overall response rate was 73.5%. NiTi rotary instruments were used by 98.4% and 50.6% of endodontists and general dentists, respectively. The main mentioned reason for not using rotary NiTi instruments was "lack of education". Among all procedural faults with NiTi, the most prevalent was "intra-canal file fracture" [88.5%] followed by "apical transportation" [71.2%] and "ledging" [68.3%]. The main factors associated with the first procedural accident were "over-use" and "excessive pressure". Dentists need more training and more comprehensive education regarding NiTi rotary instruments and techniques

invitro study on the temperature changes of dentin, irradiated by CO2 and Er: Cr;YSGG laser

Aim of this in-vitro study was the evaluation of temperature changes due to irradiation of two different lasers used for the reduction of dentinal hypersensitivity and their effect on the pulp damage. The study was done for two dentin thicknesses. Twenty intact extracted third molars were prepared by longitudinal ground sectioning for 1 and 2 mm dentin thicknesses while a thermocouple was positioned at the inner surface of the dentin disk. Thermal evaluation was assessed by a KJT digital thermometer. During the test, the data produced by the thermometer was transferred and logged into a PC via RS232 serial port. CO2 laser [Ultra pulse, 50W, 100?sec, Spot size: 0.5 mm] and Er,Cr;YSGG laser [Free-running pulse mode,0. 25W, 140?sec, 12.50 milli-joules] irradiations were randomly performed upon the dentin surfaces. The collected data was analyzed by two-way ANOVA test. The mean temperature rise in 1mm dentinal thickness was 8.57°C which was significantly higher than 3.63°C in 2mm dentin thickness [P<0.001] and higher than the threshold temperature for pulp damage; however, no significant difference was noted between the two lasers [P=0.355]. After removing the CO2 laser, the temperature decreased to the initial level faster than the time needed for Er,Cr;YSGG laser [44.47°C versus 62.82°C][P<0.001]. In other words, in both lasers the temperature decrease in 2mm dentinal disc was faster than 1mm dentinal disc. The temperature rise due to both lasers for 1mm of dentinal thickness was in excess of safe limit for the tissue and it would probably result in pulpal damage. In the case of 2mm dentinal thickness, the temperature rise was not higher than the safe limit and it would not damage the pulp in clinical conditions

Cytotoxicity of cold ceramic compared with MTA and IRM

Biocompatibility is a desirable feature for root-end filling materials. In this study we aimed to compare a new material called cold ceramic [CC] with intermediate restorative material [IRM] and mineral trioxide aggregate [MTA] using Methyl-tetrazolium bromide [MTT] assay. The materials were tested in fresh and set states: [n=108]. The cytotoxicity was compared using L929 fibroblasts as an indicator; tested materials were eluted with culture medium according to ISO: 109935 standard. Distilled water and culture medium served as positive and negative controls, respectively [n=36]. The results were evaluated at 1, 24 hours and 7 days. Data were statistically analyzed by one-way ANOVA for each time interval and material status and t-tests. The cytotoxicity of the tested materials were statistically different at the various time intervals [P<0.001]. IRM was the most cytotoxic root-end filling material [P<0.001], MTA demonstrated the least cytotoxicity followed by CC. Despite displaying the greatest cytotoxicity, IRM is approved by the American Food and Drug Administration [PDA]. Cold ceramic had significantly lower cytotoxicity compared to IRM, in all but one subgroup. Further investigations are required to assess the clinical applicability of this novel material