Effect of synthetic tissue fluid on microleakage of grey and white mineral trioxide aggregate as root-end filling materials

The success of endodontic surgery has been shown to depend partly on the apical seal. Grey mineral trioxide aggregate [GMTA] produces hydroxyapatite twice as often as white mineral trioxide aggregate [WMTA] when suspended in a phosphate buffered saline [PBS] solution. The aim of this in vitro study was to compare the microleakage phenomenon of gray and white mineral trioxide aggregates as root-end filling materials after immersion in synthetic tissue fluid [STF]. 55 single-rooted extracted maxillary anterior human teeth were divided into two experimental groups of 20 teeth each, plus 3 groups of 5 teeth each as two negative and one positive control groups. The root canals were cleaned, shaped, and laterally compacted with gutta-percha. The root ends were resected and 3 mm deep cavities were prepared. The root-end preparations were filled with GMTA or WMTA in the experimental groups. Leakage was determined using a dye penetration method. Data were analysed using analysis of variance [ANOVA] at the 0.05 level of significance. Results: The mean dye leakage was 0.40 +/- 0.1 mm for GMTA and 0.50 +/- 0.1 mm for WMTA groups, respectively. There was no significant difference between the two experimental groups [P = 0.14]. Despite the different properties and behaviours of GMTA and WMTA in STF, there were no significant differences in microleakage when using GMTA or WMTA

impact of pH on cytotoxic effects of three root canal irrigants

Cytotoxicity of root canal irrigants is important due to their close contact with host tissues. This study was to assess the possible impact of pH on cytotoxic effects of MTAD, 17% EDTA, and 2.6% NaOCl on the human gingival fibroblasts using MTT assay. Human gingival fibroblasts were exposed to the irrigants and their viability was assessed after 1, 6, and 12 h. The pH of the medium was measured in each interval. Light absorption values were measured for each culture medium using Elisa Reader device. NaOCl had significantly less cytotoxicity than EDTA and MTAD. Also irrigants cytotoxicity decreased in 12, 1, and 6 h, respectively. It seems that variation of the pH resulted in variation in the cytotoxicity of solutions; i.e., it follows the pattern of the pH variation

Efficacy of two rotary systems in removing gutta-percha and sealer from the root canal walls

The aim of this in vitro study was to compare the efficacy of two retreatment rotary systems in removal of gutta-percha [GP] and sealer from the root canal walls with and without use of solvent. Sixty single-canalled distal roots of mandibular molars were prepared and root filled with gutta-percha and AH26. Each canal was randomly allocated to receive one of the retreatment techniques, Mtwo R or ProTaper. The groups were further divided into two subgroups: with or without the use of solvent. The cleanliness of canal walls was determined by stereomicroscope and scanning electron microscopy. The results showed that Mtwo R without the use of solvent was more efficient in material removal compared to ProTaper D [P<0.05]. Most remnants were found in the apical third of the canals [P<0.05]. Mtwo R seems to be an efficient rotary system for endodontic retreatment of root canal with GP

in vitro comparative study on the antimicrobial effects of bioglass 45S5 vs. calcium hydroxide on Enterococcus faecalis

An ideal intracanal medicament should be able to eliminate any remaining intracanal microorganism. The aim of this study was to compare the antimicrobial effects of Bioglass 45S5 with calcium hydroxide on Enterococcus [E] faecalis in-vitro. Direct exposure test [DET] was used to evaluate the antimicrobial effect of Bioglass 45S5, calcium hydroxide and normal saline [control group] on 80 paper cones contaminated with E. faecalis suspension. All samples were aseptically transferred into BHI culture medium to quantify microbial concentration in periods of 1, 24, 48 and 72 hours. Turbidity of the culture medium was measured via optical density [OPD] method with a spectrophotometer [wavelength=540nm]. Results were then analysed statistically using student t-test. Mean difference of optical density between Bioglass 45S5 and calcium hydroxide appeared insignificant within 1 hour of the test period [P>0.05]; however calcium hydroxide showed significantly greater antimicrobial properties after 24 hours [P<0.05]. Antimicrobial effect of both materials displayed significant increases with time. Although both Bioglass 45S5 and calcium hydroxide exhibited antimicrobial effects against E. faecalis, neither attained complete eradication of bacteria. However, calcium hydroxide seemed to have superior disinfecting effect

comparative study between Resilon and gutta-percha as a secondary root canal filling materials: An in vitro study

Adequate root canal seal following retreatment is essential for a successful outcome. Resilon/Epiphany [R/E] obturation system has been introduced as a substitute for conventional gutta-percha/sealer method. This in vitro study compared the amount of apical microleakage of R/E with gutta-percha/AH26 [GP/AH26] sealer as secondary root canal filling following retreatment in human teeth. Fifty human single-rooted lower premolar teeth were selected. After preparing them with ProTaper rotary NiTi instruments, all the canals were obturated using GP/AH26 sealer. After 10 days, all the samples were retreated using the same rotary NiTi instruments. The samples were divided randomly into two experimental groups A and B [n=20] and positive and negative control groups [n=5]. In group A, all canals were obturated using GP/AH26 sealer and in group B all canals were obturated using R/E. After one week incubation in 37°C with 100% humidity, the amount of apical microleakage was evaluated with fluid filtration model. All the apical microleakage data were analyzed with Mann-Whitney U test Results: The mean amounts of apical microleakage were 0.317 +/- 0.287 and 0.307 +/- 0.281 microL/8min [fluid pressure=30 cm H[2]O] in experimental group A and B respectively; the difference was not statistically significant [P>0.05]. R/E seems to be a good alternative for retreatment as a secondary root canal filling material. However, Resilon/Epiphany obturation system does not completely avert microleakage