Background and Aim: Today several materials have been used for root- end filling in endodontic surgery. Optimal properties of Pro Root MTA in in-vitro and in-vivo studies have been proven. On the other hand, based on some studies, Root MTA (Iranian Pro Root MTA) and Portland cement are similar to Pro Root MTA in physical and biologic properties. The aim of this study was to evaluate bacterial leakage (amount and mean leakage time) of four root- end filling materials. Materials and Methods: In this experimental in-vitro study, seventy six extracted single- rooted human teeth were randomly divided into six groups for root-end filling with gray Pro Root MTA, white Pro Root MTA, Root MTA (Iranian Pro Root MTA), Portland Cement (type I) and positive and negative control groups. Root canals were instrumented using the step- back technique. Root- end filling materials were placed in 3mm ultra sonic retro preparations. Samples and microleakage model system were sterilized in autoclave. The apical 3-4 mm of the roots were immersed in phenol red with 3% lactose broth culture medium. The coronal access of each specimen was inoculated every 24h with a suspension of Streptococcus sanguis (ATCC 10556). Culture media were observed every 24h for color change indicating bacterial contamination for 60 days. Statistical analysis was performed using log- rank test with P<0.05 as the limit of significance. Results: At the end of study 50%, 56.25%, 56.25% and 50% of specimens filled with Gray Pro Root MTA, White Pro Root MTA. Root MTA and Portland Cement (type I) had evidence of leakage respectively. The mean leakage time was 37.19±6.29, 36.44±5.81, 37.69±5.97 and 34.81±6.67 days respectively. Statistical analysis of data showed no significant difference among the leakage (amount and mean leakage time) of the four tested root- end filling materials (P=0.9958). Conclusion: Based on the results of this study, there were no significant differences in leakage among the four tested groups at 60 days. The results suggest that Root MTA and Portland Cement can be used as less expensive root filling materials.

Background and Aim: Mineral Trioxide Aggregate (MTA) is a material used in many endodontic problems.Recently a number of studies have reported that Portland Cement (PC) and MTA have similar physical, chemical and biologic properties. In addition, a material known as Root MTA which is produced in Iran has been claimed to have similar properties to Pro Root MTA. If these claims are true, possible use of PC and Root MTA in clinic instead of Pro Root MTA will be quite cost effective. The aim of this study was to investigate the toxicity of Pro Root MTA, Root MTA and Portland Cement on L929 mouse fibroblasts.Materials and Methods: In this experimental study 0, 4, 24 hours and 7 days' extracts of materials were transferred to cell culture plates containing L929 fibroblasts. After 24 hours incubation, cells were stained by Neutral Red (NR), and optical density (OD) of each cell was read with ELISA reader. Data were analyzed using Tukey HSD and one way analysis of variance. P<0.05 was considered as the level of significance.Results: In all surveyed groups and negative control group, at all time points separated cells from the base of the well were round. Refraction which is a characteristic of cellular death was not observed, whereas the separated cells from the base of well in positive control group showed refractional characteristic.Conclusion: Based on the findings of this study Pro Root MTA, PC and Root MTA have the same biocompatibility. PC seems to have the potential to be used in the same clinical situation as MTA. However in order to replace MTA with these less expensive materials more in vitro and in vivo studies are suggested.

Acrylamide was polymerized at 40 and 80 degrees C in presence of 4,4"-azobis-4cyanovaleric acid by radical polymerization, to high conversions. The polyacrylamides were isolated by precipitation in methanol. After drying, the limiting viscosity numbers, [eta], and apparent molecular weights of polyacrylamides were determined viscometrically by several empirical equations, in distilled water and also by GPC. The dependence of limiting viscosity number on percentage conversion is discussed, and the significance of polymer branching at 40 and 80 degrees C is assessed.

Background and Aim: The goal of endodontics is to seal the root canal system from the orifice to apical constriction completely and tridimensionally. Hence perforations during root canal therapy, because of caries or resorptions must be sealed and obturated with ideal materials. The aim of this study was to histologically compare two kinds of mineral trioxide aggregate Root MTA and Pro Root MTA for furcal perforation repair in developed teeth in dog. Materials and Methods: In this experimental study, thirty teeth consisting of second, third and fourth mandibular premolars of five German shepherd dogs were selected. Twenty-four teeth were randomly divided into four experimental groups (6 teeth each). One pair of Root MTA and Pro Root MTA groups studied in one month and the other in three months intervals. Positive and negative control groups was each contained three teeth. In positive control group, perforations were not treated and negative control group contained intact teeth. In experimental groups perforations repaired after one week exposure to oral cavity with Root MTA or Pro Root MTA. After time intervals animals were subjected to vital perfusion and 6 mm histologic sections were prepared. Inflammation and hard tissue formation were ranked by Cox criteria. Data were analysed using Mann-Whitney and Chi-Square statistical tests with P<0.05 as the limit of significance. Results: There was statistically significant lower inflammation and higher hard tissue formation in three months Root MTA and Pro Root MTA groups compared to one month interval (P<0.05). There was no statistically significant difference in inflammation and hard tissue formation between Root MTA and Pro Root MTA in each intervals (P>0.05). Conclusion: Mineral Trioxide Aggregate is an adequate material for furcal perforation repair in dog’s teeth. Root MTA could be a good substitute for Pro Root MTA considering the lower cost and similar characteristics.

Any change in the pipe discharge, caused by valve closure or shutting off the pump, results in fluctuations in velocity and pressure of the flow; which develops transient flow in the water conveyance system. This flow causes various risks by creating rapid and short waves. A model composed of a reservoir, a polyethylene pipe and check valve was made to examine hydraulic transient flow in branched pipe lines. The model was made in the laboratory of hydraulic and physical models of water science faculty in Shahid Chamran university. The experiment were done on different length and diameter ration of branch to mainline in a constant discharge of 4 lit/s. the data acquired of installed pressure transducers in different points of the model were used to demonstrate how pressure wave transformed and became transient and the results are presented in the following diagrams. As maximum and minimum pressures downstream the branches decrease significantly in compare with the system without branching, some equations were proposed for estimating the maximum and minimum pressures downstream the branches.