[Comparison of the effect of three root canal irrigant protocols for removing smear layer on the apical microleakage of tubliseal sealer]

Complete root canal seal is one of the most important aims of root canal treatment. Elimination of smear layer plays an important role in this regard. The purpose of this study was to compare the apical microleakage of Tubliseal sealer when 17% EDTA, 7% citric acid, or 20% citric acid was used to remove the smear layer. In this experimental study, 80 single rooted teeth were selected. The crowns were removed from cemento enamel junction [CEJ]. Instrumentation of the canal was performed by the step back method. The teeth were randomly divided into 3 experimental groups of 20 and 2 control groups of 10 [positive and negative groups]. Final irrigation was implemented as follows: group 1; EDTA 17% + NaOCL, group 2; 7% citric acid + NaOCL and group 3; 20% citric acid + NaOCL. Then, the groups were obturated with gutta percha and Tubliseal sealer. Lateral condensation technique was carried out in all groups. The teeth were stored in 100% humidity and 37°C for 48 hours. The root surfaces other than the apical 2mm were covered with 2 layers of nail polish. After that, the teeth were placed in metylene blue dye for 72 hours. Then, the teeth were sectioned longitudinally with a diamond disk and the degree of dye penetration was measured. The results were statistically analyzed by one-way Variance and Post Hoc Tukey tests. A statistically significant difference was found between the groups [p<0.05]. The least amount of dye penetration [2.59mm] was belonged to 17% EDTA group and the highest mean dye penetration occurred in the group in which 20% citric acid was used [3.59mm]. The results of this in vitro study indicated that when a ZOE-based sealer is used for obturation of the root canal system, EDTA is recommended to remove the smear layer. Furthermore, it can be concluded that the main purpose of removing the smear layer is not to clean the dentinal tubules from organic and inorganic debris, but also to create a dentinal surface structure that best fits the characteristics of the sealer used for root canal obturation

Antibacterial substantivity of three concentrations of doxycycline on bovine root dentin infections: an in vitro study

The aim of this in vitro study was to compare the antimicrobial activity and substantivity of three concentrations of doxycycline on bovine root dentin infections. Seventy dentin tubes prepared from intact bovine incisors were infected in vitro for 14 days with Enterococcus faecalis. The specimens were divided into five groups according to the used intracanal irrigation as follows: Group 1: l00mg/ml of doxycycline hydrochloride solution [DHS] [n=20]; Group 2: 50mg/ml of DBS [n=20]; Group 3: l0mg/ml of DHS [n=20]; Group 4: positive control [infected dentin tubes] [n=10]; and Group 5: sterile saline [negative control] [n=10]. Dentin chips were removed from the canals with sequential sterile low - speed round burs with increasing diameters of ISO sizes: 025, 027, 029, 031, and 033 at experimental times of 0, 7, 14, 21, and 28 days. After culturing, the numbers of colony-forming units [CPUs] were counted. Data were analyzed using analysis of variance and covariance with repeated measures [ANOVA] to indicate differences between the experimental groups and the positive control. One-way ANOVA [Tukey's method] was used to indicate differences within each layer. The numbers of CFt/s in aJJ three experimental groups were minimum in first cultures, and the obtained results were significantly different from each other at any time period [P<0.05]. In first culture, the groups 1 [0.400 +/- 0.699] and 3 [4.700 +/- 3.683] showed the lowest and highest numbers of CPUs, respectively. In each group, the numbers of CPUs increased significantly by time lapse [P < 0.05]. Under the conditions of this study, it can be concluded that doxycycline HC1 may be useful as a substantive antimicrobial agent

[Comparing the bacterial leakage in endodontic therapy following using EDTA as a irrigation and AH26 or tubliseal as selars]

Complete root canal seal is one of the most important aims of root canal treatment. For this purpose, elimination of the smear layer and the kind of sealer used have important roles. The aim of this study was to compare the sealing ability of two sealers [ZOE and resin based] against the microleakage of entrococcus faecalis when used in association with three different root canal irrigants [17% EDTA, 7% citric acid, 20% citric acid]. In this experimental study, 170 single - rooted extracted human teeth were selected. Step back canal preparation was performed to Iso size No. 40 in the apical portion of the canals with 5.25% Naocl irrigation. The teeth were randomly divided into 8 groups: six experimental groups of 25 teeth and two control groups of 10 teeth. Final irrigation in groups 1 and 2 was preformed with EDTA+NaClO; in groups 3 and 4 with 7% citric acid+NaClO; and in groups 5 and 6 with 20% citric acid+NaClO. Groups 1, 3 and 5 were obturated with guttapercha and AH[26] sealer, and groups 2, 4 and 6 with guttapercha and Tubliseal sealer using lateral condensation. The 10 positive control teeth were obturated with a single guttapercha cone and the 10 negative control teeth were thoroughly obturated with gutta-percha and sealer. After 48 hours in 100% humidity and 37°C temperature, the roots were assembled in the designed system for this experiment. A fresh solution of entrococus faecalis was injected to the system every 3 days. The samples were evaluated daily for 160 days and the time of culture contamination with E. faecalis was registerd in each case. ANOVA and Duncan tests were used to analyze the results. All the samples in positive control group were infected after 24 hours. None of the negative control samples were infected after 160 days. Group 1 [EDTA+AH[26]] and group 3 [7%citric acid+AH[26]] had no significant difference with group 2 [EDTA+Tubliseal] and group 5 [20% citric acid+AH[26]], but group 2 and 5 were significantly different [P<0.001]. Group 4 [7% citric acid+Tubliseal] was not significantly different from group 6 [20% citric acid+Tubliseal] but they both were significantly different from the other four groups [P<0.001]. In this study 20% citric acid used in association with AH[26] showed the greatest microleakage mean time. The least microleakage mean time occurred in the group for which 20% citric acid was used in association with Tubliseal