document: the residual and resistant microorganisms have been recognized as the basic reason for failures in root canal treatments . 
   fungi , chemoorganotrophic eukaryotic microorganisms , may play a key part in periradicular diseases . while they have been found sporadically in initial root canal infections , 
   failure of some endodontic treatments may therefore be explained by the presence of candida albicans in the oral flora . 
   it is reported that in 20% of endodontic treatment failures , c. albicans is present . 
   candida species , which have a tendency to invade dentin , are regarded as dentinophilic microorganisms . 
   the presence of c. albicans in endodontic treatment failures may be the result of coronal leakage after , or contamination during , the endodontic treatment . 
   several factors , such as an ability to survive despite a lack of nutrients or resistance to intracanalicular treatment materials , may result in c. albicans remaining in the root canal system . c. albicans has been found in some failed endodontic treatments ; a phenomenon that might be explained by the invasive nature of this fungus or its resistance to some intracanalicular medications , e.g. , calcium hydroxide . 
   if repeated treatment has either failed or is unfeasible , the only alternative is a root - end resection . 
   apical sealing , avoiding contamination , and reducing the number of microorganisms , including bacteria and fungi , influence the success rate of such treatment . therefore , the antibacterial and antifungal properties of root - end filling materials are important to the outcome of these procedures . 
   mineral trioxide aggregate ( mta ) was introduced in 1993 and , after different examinations , approved , in 1998 , by the us food and drug administration as an endodontic biomaterial , used in root - end filling , vital pulp capping , apexification , and root or furcal perforation repair.[58 ] mta is marketed as gray and white . however , because of the tooth - discoloring properties of gray mta , white mta has been pushed to replace it . 
   mta has a number of advantages , including excellent sealing ability , biocompatibility , high alkalinity , radiopacity , antimicrobial effects , and resistance to fluid and blood contamination.[911 ] in spite of having disadvantages , such as delayed setting time , poor handling properties , and high price , mta , because of its physical and chemical properties , has become the gold standard of root - end filling materials . 
   mta - angelus particles are not as homogenous as proroot mta . in comparison to proroot mta , 
   mta - angelus shows several advantages , such as good marginal adaptation , good sealing , sealing ability in mineralized tissues with complete closure , and has been reported to be inflammation - free in most cases.[1517 ] mta - angelus has an excellent antibacterial effect and a strong fungicidal effect against c. albicans . 
   while both the white and gray mta - angelus have arsenic in their structures , white mta - angelus has the benefit of containing arsenic levels below the limit set by the iso 9917 - 1 standard . 
   a limited number of researches have compared the antifungal effects of proroot mta and mta - angelus . 
   however , such studies have been conducted using agar diffusion test ( adt ) , a method that does not seem appropriate because of low solubility and diffusibility of mta . 
   the aim of this in vitro study was to evaluate and compare the antifungal properties of fresh and set proroot mta and mta - angelus , in concentrations of 50 mg / ml and 100 mg / ml , against c. albicans at 1- , 24- , and 48-hour time points . 
   the null hypothesis of this study was that there is no difference in the in vitro antifungal properties of these two materials . 
   the antifungal activity of proroot mta ( dentsply tulsa dental , tulsa , usa ) as well as mta - angelus ( angelus , londrina , brazil ) was evaluated against c. albicans . 
   the culture of sabouraud dextrose agar ( merck , darmstadt , germany ) was prepared according to the manufacturer 's instructions with a definite ratio of powder to liquid . 
   samples of live c. albicans , ( atcc 10231 ) provided by scientific research organization , ( tehran , iran ) were subcultured on the sabouraud dextrose agar plates . the agar plates , containing the fungus , were then maintained at 37c . 
   times and conditions for the culture of c. albicans in this study were determined following the nccls standards ( national committee on clinical laboratory standards ) . 
   a total of 50 culture wells were divided into four experimental groups ( freshly mixed mta , freshly mixed mta - angelus , 24-h set mta , 24-h set mta - angelus ) and two control groups ( positive control , negative control ) . 
   the root canal filling materials were prepared according to their instructions and then mixed with the appropriate volume of sterile water to reach the concentrations of 50mg / ml or 100mg / ml . for the set groups , the mixture was prepared and left for 24 hours . 
   each group consisted of 10 wells , and the control groups consisted of five wells each . 
   suspensions were then made by the addition of several fungal colonies from the surface of the sabouraud dextrose agar plates to sabouraud dextrose broth media . 
   a final concentration of 10 cfu / ml ( colony forming unit / milliliter ) was achieved , as recommended by the nccls , via microscopic cell counting . 
   wells with 1 ml of c. albicans suspension mixed and 1 ml of sabouraud dextrose broth media without root end - filling materials served as positive control and wells with 1 ml of sabouraud dextrose broth media without c. albicans served as negative control . 
   all wells were incubated at 37c and evaluated for 1 , 24 , and 48 hours by an independent observer by assessing the colonies of c. albicans in each well . 
   this assessment was based on the turbidity of the suspension in the tubes . at each time point , 0.02 ml of each suspension was cultured on sabouraud dextrose agar plate to confirm c. albicans growth . 
   after the culture of 0.02ml of the treated suspension on the agar plates , the fungal growth was assessed at 1- , 24- , and 48-hour time points . while fungal growth was not observed in any of the negative control groups , 
   after 1 hour , both the mta and mta - angelus were incapable of killing c. albicans . 
   the results were the same for both freshly mixed and set samples at both concentrations ( 50 and 100 mg / ml ) . increasing the incubation time to 24 hours and 
   both materials were fungicidal for c. albicans at both concentrations of 50 and 100 mg / ml , and in both states of fresh and set [ table 1 ] . 
   comparison of proroot mta and mta - angelus in concentration of 50 mg / ml and 100 mg / ml at 1 , 24 , and 48-h time intervals there was no significant difference between using the two materials at either of the concentrations or either of the 1-hour , 24-hour , or 48-hour time points ( p<0.05 ) . 
   in this study , the antifungal properties of proroot mta and mta - angelus against c. albicans in two concentrations and in fresh and set situations were compared by using tube - dilution test . because the two materials elicited the same reaction against c. albicans in different conditions , the null hypothesis that there is no difference in the in vitro properties of these two materials has to be accepted . the most common method for assessing the antifungal or antibacterial activity of root - end filling materials 
   however , several parameters , such as lack of standardization of inoculum density , adequate culture medium , agar viscosity , plate storage condition , size and number of specimens per plate , time and temperature of incubation , and reading point of the inhibition zones , can affect the results of the adt . 
   the method used in this in vitro study was the tube - dilution susceptibility test ; an efficient method for evaluating antifungal characteristics of materials . in this technique , direct contact between c. albicans and the experimental materials was allowed , allowing a more realistic interaction . 
   because of possible changes in the chemical structure of the products , root - end filling materials should be tested in two situations ; one where the material is used immediately after mixing , and another , where it is used after having been allowed to reach its final chemical composition , or set state . in this study 
   , proroot mta and mta - angelus were tested in freshly mixed and set states , to mimic clinical use of the materials . after setting , 
   consequently , the perceived difference in antifungal patterns of the materials may be a result of the differences in the degree of setting . 
   however , in our study , the results were similar in the two different states for all tested materials . based on nccls standards , 
   the results of this study showed that c. albicans was not affected by the freshly mixed and set , proroot mta and mta - angelus , at 1 hour . 
   however , these materials were effective in eliminating c. albicans by the 24-h time point . 
   some studies have reported the inhibitory effect of proroot mta and mta - angelus on c. albicans by determining the diameter of the inhibition zones in millimeters , and have resulted conclusions similar to this study . 
   the presence of calcium hydroxide , produced by a hydration reaction from the mixing of mta with water , and an increase in ph , as a result of the release of hydroxyl ions , is probably the mechanism of the antimicrobial activity of mta - angelus . 
   they suggested that the presence of calcium hydroxide is capable of , initially , reducing and , ultimately , eliminating the fungus . 
   it is important to mention that the results presented in this study were obtained under in vitro conditions , and may not accurately describe in vivo activity . 
   further studies are necessary to investigate the effect of these materials on bacteria and fungi in clinical application . 
   this study shows that mta - angelus has an effective antifungal property comparable to proroot mta at concentrations of 50 and 100 mg / ml .
summary: background : fungi may play a key part in periradicular diseases . the aim of this study was to evaluate and compare the antifungal properties of two root - end filling materials , proroot mineral trioxide aggregate ( mta ) and mta - angelus , against candida albicans using tube - dilution test.materials and methods : the antifungal properties of proroot mta and mta - angelus against c. albicans was assessed at 1 , 24 , and 48 hours following administration of two concentrations of the antifungal agents ( 50 and 100 mg / ml ) . 
   a total of 50 culture wells were divided into four experimental groups ( freshly mixed mta , freshly mixed mta - angelus , 24-h set mta , and 24-h set 
   mta - angelus ) and two control groups . 
   each well was prepared for one specific agent with a specific concentration . 
   for the set groups , the mixture was prepared and left for 24 hours . 
   one milliliter of suspension of fungal colonies with concentration of 104 cfu / ml was then added to the mixtures in each well . 
   all wells were incubated at 37c and assessed at 1 , 24 , and 48 hours . 
   this observation was based on the turbidity of the suspension in the tubes . at each time point , 0.02 ml of each suspension was cultured on a sabouraud dextrose agar plate to confirm c. albicans growth . 
   the results were analyzed using kruskal - wallis test.results:although all fresh and set samples were incapable of killing c. albicans at 1 hour , they demonstrated fungicidal ability on agar plates at 24 and 48-hour time points.conclusion:mta-angelus proved to be an effective antifungal agent compared to proroot mta at concentrations of 50 mg / ml and 100 mg / ml .