[Evaluation and comparison of apical leakage following root canal dressing with different calcium hydroxide preparations]

The use of calcium hydroxide as an intra-canal medication can lead to leakage of permanent obturation of the canal and failure of the treatment. The purpose of this study was to evaluate the rate of the remained calcium hydroxide in radiographic views and their effect on apical leakage. For this study, 75 human extracted premolar teeth were divided into 5 groups randomly. All the teeth were prepared by step back technique and apical foramen enlarged to number 30 file. Aria dent calcium hydroxide was introduced into the canal in group 1. In group 2, Barium sulfate was added to calcium hydroxide powered in 1 to 9 proportion and the methods was gone on the same as in group 1. Dentsply calcium hydroxide was mixed with glycerin-based aqueous and introduced into the canal in group 3. Calcium Hydroxide paste [Pulpdent] was introduced into the canal with its special needle. In group 4 and 5, there was no calcium hydroxide as a control group. The canals were prepared with one sixe larger than master apical file, MAF [35 file size] to remove calcium hydroxide. The remaining of calcium hydroxide was accessed radiographically and compared using Kruskal Wallis test. Dye leakage in the 5 groups was compared, using ANOVA and Tukey tests. There was no significant difference between the five groups when dye leakage was compared, but calcium hydroxide paste [Pulpdent] shows more remained material when evaluated radiographically. The use of calcium hydroxide paste with methyl cellulose base for intra-canal medicament is not recommended

in vitro comparative study of apical microleakage of biocalex and white MTA as root-end filling materials

For sealing a cavity prepared in endodontic surgery, there is a need for a material to obtain an apical seal and prevent bacterial and tissue exudates. The purpose of this study was to compare the sealing ability of Biocalex and white MTA as root-end fillings. In this in vitro experimental study, 36 single-rooted extracted human adult teeth with minimum root curvature were cleaned, shaped and obturated with lateral condensation technique, 3 mm of the root apices were resected and a 3 mm deep retrograde cavity was prepared. Teeth were assigned randomly into two groups of 15 teeth each and retrofilled with Biocalex and White MTA. Three teeth served as positive and three teeth served as negative controls. All root surfaces, except the ending part, were covered with two layers of nail polish. Then the roots were stored in 2% methylene blue for 72 hours and then embedded in polyester resin. Next, they were sectioned buccolingually by diamond bur and maximum extent of dye penetration was evaluated through stereomicroscope. Statistical analysis was carried out by student t-test. The level of significance was set at 95%. It was shown that retrofills with Biocalex had significantly less microleakage compared with white MTA. The findings of this study showed that retrograde filling with Biocafex can achieve proper sealing ability and can be used as an alternative for MTA [P<0.001]

influence of instrument application frequency on apical extrusion of debris in three instrumentation techniques

Various kinds of hand-held or rotary techniques are used for mechanical preparation of the canal. The purpose of this study was to assess the influence of the number of applications on apical extrusion of debris in conventional and two rotary instrumentation techniques [Profile, Flex Master]. In this in vitro study, 75 extracted single-rooted human mandibular premolars with curvature between 0-10 degrees were selected and divided into three groups of 25 teeth each. All teeth were shortened to length of 15 mm by cutting the crown. Group H was prepared by hand step back technique, group P was prepared by profile system and group F was prepared by Flex Master system. The number of applications was according to manufacturer recommendation. For collection of debris, vials of distilled water were used that were weighed before preparation by 0.0001 weighing machine. At the end of canal preparation, vials were completely dried and weighed again. The difference between the weights of vials in two stages was the weight of debris extruded from apical foramen. The mean weight of debris in various numbers of applications within each system was compared by one-way variance analysis. Comparing the various numbers of applications in each system, it was noted that only in profile group, with increasing the number of applications, the quantity of debris extrusion was reduced. Unused profile instruments induce more extrusion of debris from apical foramen, rather than used ones

Comparison of the extruded apical debris rate following rotary and hand instrumentation techniques during endodontic retreatment

Non-surgical retreatment is a way to correct the factors responsible for the failure of previous endodontic treatment. In recent years, rotary instrumentation systems have created a new option for both clinicians and patients. The aim of the present study was to quantify and compare the amount of debris extruded from apical foramen during endodontic retreatment using rotary and hand instrumentation techniques with and without use of chloroform. In this invitro experimental study, root canals of 96 extracted single-root human teeth were instrumented by passive step back technique in three different working lengths: optimum, over and under [three subgroups: a, b, c]. they were then obturated by a combination of cold lateral and warm vertical compaction methods. After removal of gutta-percha, re-instrumentation was performed in three groups as follows: group A; stainless sled K-type hand files plus chloroform, group B; rotary Ni-Ti files plus chloroform and group C; rotary Ni-Ti files without chloroform. Finally, the weight of extruded debris was blindly determined. The results were analyzed by Univariate ANOVA. In all groups, the mean weight for extruded debris was not more than 0.37 gr. The weight of extruded debris was ranked as: Group B>Group C>Group A. The differences between three groups and subgroups were statistically significant [P<0.001]. The results of this study showed that the largest amount of extruded debris during retreatment was found after using rotary files with solvent and in canals with overfilled obturation