mineral trioxide aggregate ( mta ) was first introduced in 1990s and it has been proven to be a superior material regarding with its excellent sealing ability , biocompatibility and hard - tissue forming capacity . it also possesses ideal properties such as its antimicrobial effect , dimensional stability , radiopacity and tolerance to moisture . clinically , mta is currently being used for a variety of endodontic and restorative dental applications such as vital pulp therapy , apexification , repair of root perforations , and root - end filling . although mta is considered to have ideal properties , its usage remained limited due to its high - cost , difficult handling characteristics , long setting time and potential of discoloration . these shortcomings of mta led to the continuous efforts in developing the modified versions of mta . first modification was performed on the original gray formula ( proroot mta ) by the manufacturer ( dentsply tulsa dental , tulsa , ok , usa ) producing a tooth - colored formulation ( white mta ) in order to overcome the potential discoloration problem . white mta mainly differs from the gray mta in the absence of iron . in 2001 , mta angelus ( mta - a ) was introduced as an alternative to proroot mta and used in certain regions with its lower price . the chemical difference between proroot mta and mta - a is that mta - a lacks calcium sulfate dehydrate as one of its main compounds , resulting in that mta - a has shorter setting time than proroot mta ( 165 minutes for proroot mta , while 10 minutes for mta - a ) . mta - a is less radiopaque than proroot mta due to the lower content of bismuth oxide in its composition . bioaggregate ( ba ) was released in 2007 as a bioceramic material , in which most of the constituents are similar to those in white mta . it differs from mta by being aluminum -free and containing calcium phosphate monobasic and tantalum pentoxide . aluminum - free content is one of the most significant features of the ba since it is known that aluminum has a toxic effect on the human body . a novel mta material called mta - plus ( mta - p ) , which is claimed to have a finer particle size than the currently available mta products that has been introduced on the market . because mta - p has been recently available in the market , there are not many studies reported on this material . x - ray diffraction ( xrd ) is a powerful method used for the identification and characterization of the crystalline phase composition of the materials . although xrd analysis of the relatively new material , mta - p , has recently been carried out and studies comparing the major constituents of this material with other mta derivatives are still lacking . the purpose of this study was to investigate and compare the crystalline structures of mta - p , white mta - a and diaroot ba by xrd analysis . materials used in this study included mta - p ( compounded by prevestdenpro , jammu , india for avalon biomed inc . , bradenton , fl , usa ) , white mta - a ( angelus , londrina , pr , brazil ) and diaroot ba ( innovative bioceramix , vancouver , bc , canada ) . the mta - p is provided with either water or a gel for mixing . in the current study , phase analysis was carried out on both the powder and the set forms of tested materials . for the powder form , each specimen was placed into the sample holder and packed with a glass slide to provide a uniform surface . for the set form , each mixture was prepared according to their manufacturer 's instructions was placed into a mold and the upper surface of the specimen was swept with a spatula . the set samples were set for 3 days at 37c and 100% humidity in the incubator . an x - ray diffractometer ( xpert pro mpd , panalytical , almelo , the netherlands ) with ni filter and cuka radiation running at 45 kv voltage and 40 ma current was used in the present study . the scan range was set at 2702 and with a scan speed of 22 per minute . each phase ( crystalline substance ) of a compound has a characteristic diffraction pattern consisting of several x - ray peaks . the peaks at the specified intensity representing the diffraction patterns of the tested materials were matched with the standard data documented in the powder diffraction files ( pdf ) found in the international centre for diffraction data ( icdd ) database . x - ray diffraction patterns of mta - plus in the set ( a ) and powder ( b ) forms . ( bo , bismuth oxide ; c3s , tricalcium silicate , c2s , dicalcium silicate ; ch , calcium hydroxide ; a , anhydrite ) x - ray diffraction patterns of mta - angelus in the set ( a ) and powder ( b ) forms . ( bo , bismuth oxide ; c3s , tricalcium silicate , c2s , dicalcium silicate ; c3a , tricalcium aluminate ) x - ray diffraction patterns of bioaggregate in the set ( a ) and powder ( b ) forms . ( to , tantalum oxide ; c3s , tricalcium silicate , c2s , dicalcium silicate ; ch , calcium hydroxide ) both mta - p and mta - a showed strong peaks of bismuth oxide at 27.37 , 33.03 and 46.30 2. there were no peaks for bismuth oxide in the ba sample . all samples comprised tricalcium silicate indicated by the main peaks at 32.14 , 32.49 and 34.31 and dicalcium silicate indicated by the main peaks at 32.05 , 32.13 and 32.59 2. mta - a showed peaks at 33.16 , 47.62 and 59.27 2 representing tricalcium aluminate . portlandite ( calcium hydroxide ) was identified in mta - p groups and powder form of ba . anhydrite was observed in powder mta - p and ettringite ( hexacalcium aluminate trisulphate hydrate ) was observed in the set mta - p . the identification of the major constituents or compounds present in a material is important as it will contribute to understanding of the material 's physical , chemical and mechanical properties . the use of xrd permits the identification of the major constituents or compounds present in a material . the key principle of the technique is based on identifying the diffraction pattern of each crystalline phase characterized by a unique set of peaks ( known as bragg 's peaks ) , with a specific diffracted intensity ( y - axis ) and diffracted angle at a specified position . phase identification is accomplished by comparing the data of the tested specimens by using peaks and relative intensities with a very large set of  standard  data provided by the icdd . mta contains largely crystalline phases , with the calcium silicate hydrate being the only amorphous phase . all the tested materials in this study had two common constituents , tricalcium silicate and dicalcium silicate . tricalcium silicate is the major component in the formation of calcium silicate hydrate which gives early strength to the cement . dicalcium silicate hydrates more slowly than tricalcium silicate and is responsible for the latter strength . mta - a has also included the tricalcium aluminate phase as one of its main phases . tricalcium aluminate is the most reactive constituent and reacts rapidly with water , however , its contribution to the strength is very little . the crystal structure of ba has been recently investigated by xrd analysis and all the crystalline phases were identified . the xrd results obtained from ba samples in this study were largely similar to those of park et al . tantalum oxide , tricalcium silicate ba also includes hydroxyapatite and amorphous silicon oxide together with the main cementitious and radiopacifier phases . the hydroxyapatite and amorphous silicon oxide are added by the manufacturer to reduce the levels of the calcium hydroxide , which is a weak hydration product of calcium silicates . portlandite was identified in the powder form of ba and this is in contrast to the study by park et al . , which demonstrated portlandite only in set samples . hydroxyapatite peaks were not observed in this study differing from the study by park et al . the absence of aluminum specified by the manufacturer was also verified in the present study . mta - p is a new version of mineral trioxide aggregate , which is claimed to be similar in composition to the other mta products . it has been released by the manufacturer highlighting the features of finer particle size and lower cost . mta - p is sold with either distilled water or anti - washout gel intending to improve its anti - washout resistance . determined that the crystalline particles in mta - p were smaller than those present in proroot mta although the chemical compositions were found to be similar . smaller particle size is important for the physical properties as it will increase the surface available for hydration and cause greater early strength as well as ease of handling . there are not many studies published comparing the new mta - p and the other mta products , which have been extensively investigated . formosa et al . were first to investigate the chemical and physical properties of the novel mta - p . they used the xrd method to identify the crystalline phases of mta - p and made a comparison between its two set forms , one mixed with the anti - washout gel and the other mixed with the distilled water . the phases identified in their study were similar for each mixture and included tricalcium silicate , dicalcium silicate , bismuth oxide and portlandite , which also corroborated with the findings of this study . they also observed weak peaks of ettringite , which were also identified in the set sample of mta - p of the present study . it is known that the ettringite peaks are formed as a result of reaction between tricalcium aluminate and water in the presence of calcium sulfate . our results showed that mta - p powder consisted of anhydrite as the calcium sulfate phase and it is likely that small amounts of tricalcium aluminate are present considering the production of ettringite in set samples . the aluminate phase results from the addition of alumina in the mixture and alumina helps reducing the burning temperatures required to make the cement . the quantity of anhydrite is important for controlling the  flash set  phenomenon attributed to the high reactivity of the aluminate phase with water . it can be controlled by adding a sulfate - involving agent such as gypsum or anhydrite , which delays the setting time . although mta - a had an aluminate phase , it did not contain calcium sulfate and this results in a shorter setting time ( ~10 min ) of the material . mta - p and mta - a contained the same constituent , bismuth oxide , as a radiopacifier while ba included tantalum oxide instead . considering that tantalum oxide is the major difference between mta and ba , it may be important to examine the differences between bismuth oxide and tantalum oxide in terms of toxicity and biocompatibility . bismuth oxide , which is one of the main compounds of mta , may not contribute to its excellent biocompatibility . steinemann reported a strong inhibition zone when osteoblasts were grown , whereas fibroblasts proliferated well on the tantalum disc . however , they could not infer whether those results were due to the surface roughness or the chemical nature of the material . the set mta - p exhibited strong peak of calcium hydroxide , which is in accordance with the results of a previous study by camilleri et al . the calcium hydroxide peak in this study was found to be much more pronounced in mta - p than in the other mta products tested . the high portlandite peak , which is indicative of a greater rate of reaction , is reported to be related to the fine grinding of mta - p cement . all the tested materials were similarly composed of tricalcium silicate and dicalcium silicate crystalline structures . mta - p showed anhydrite in a powder sample and ettringite in a set sample differing from mta - a and ba . in addition , set mta - p exhibited a strong peak of portlandite , which is attributable to its fine grinding property . mta - a differed from mta - p and ba by the presence of tricalcium aluminate phase . ba mainly differed from mta - a and mta - p by the radiopacifier added . mta - p and mta - a contained the same constituent , bismuth oxide , as a radiopacifier while ba included tantalum oxide instead .
objective : the purpose of this study was to investigate and compare the crystalline structures of recently released mta plus ( mta - p ) , mta angelus ( mta - a ) , diaroot bioaggregate ( ba ) by x - ray diffraction ( xrd ) analysis.materials and methods : phase analysis was carried out on powder and set forms of tested materials . 
 the powder specimens placed into sample holders that were packed with a glass slide and the set samples prepared according to the manufacturer 's instructions were placed into molds . 
 the samples after being set for three days at 37c and 100% humidity in an incubator were mounted onto the xrd machine and phase identification was accomplished using a search - match software program.results:xrd findings indicated that major constituents of mta - p were bismuth oxide , portlandite , dicalcium silicate and tricalcium silicate . the crystal structure of mta - a were similar to those of mta - p except for the absence of portlandite . 
 additionally , mta - a had tricalcium aluminate differing from mta - p . 
 ba mainly differed from mta - p and mta - a by the radiopacifier ( tantalum oxide - to ) in its composition.conclusions:the majority of constituents of the tested materials have shown similarity except for the presence of tricalcium aluminate in mta - a and the inclusion of to in ba . in addition , set mta - p showed a strong peak of portlandite .