the fundamental goals of endodontic therapy are to achieve successful cleaning and 
 shaping of root canals and a hermetic apical seal . an ideal root canal sealer should adhere to both dentin and the 
 core filling material . methacrylate resin - based sealers , based on dentin adhesion 
 technologies , have been developed in an attempt to seal the root canal system more 
 effectively , improving bonding to radicular dentin , but their utilization requires removal of the smear layer and 
 collagen exposure , because retention is largely achieved by micromechanical interlocking 
 between collagen matrix and resin . ethylenediaminetetraacetic acid ( edta ) has been widely used for this purpose as the 
 final irrigant before applying methacrylate resin - based sealers ; however , the results were poor regarding its bond strength adhesion to 
 root dentin , whereas the non - bonding ah plus sealer presented greater adhesion . no correlation has been found between apical microleakage and sealer bond strengths to 
 intraradicular dentin in vitro . while we assume that 
 preventing effective microleakage is perhaps more important for endodontic application 
 than bond strength , there is no 
 universally accepted method for the evaluation of leakage . each has its limitations , being governed by electrical , 
 filtration and/or diffusion laws . comparisons between different methods point to contradictory results , and , therefore , 
 questionable clinical relevance . push - out bond strength testing has become a common method for determining the 
 effectiveness of adhesion between endodontic materials and intraradicular dentin . ( 2008 ) have 
 correlated the push - out bond strength and sealing ability with the fluid filtration 
 method of adhesive cements routinely used for fiber - post bonding , but to date there is 
 no documented correlation using methacrylate resin - based sealers . we believe that this 
 aspect is very important , because any filtration can hydrolytically degrade the adhesive 
 interface . hence , the purpose of this in vitro study was to 
 quantitatively assess the bond strength to dentin root canal and the sealing properties 
 of two methacrylate resin - based sealers and their corresponding core points ( realseal 
 and endorez ) , then compare them with the gold standard conventional nonbonding ah 
 plus / gutta - percha . the push - out test and fluid filtration method were used to test the 
 null hypothesis that there is no difference in the bond strength and sealing properties 
 of realseal , endorez systems and ah plus / gutta - percha . we used 60 human anterior teeth , recently extracted for periodontal reasons from 
 anonymous subjects under a protocol ( n 11/2011 ) approved by the ethics committee of the 
 school of dentistry , university of granada . all teeth had single straight root canals 
 and closed apices and none showed caries lesions or had received restorative or root 
 canal treatment . after extraction , any calculus and soft tissue was removed and they 
 were stored in 0.1% thymol diluted in distilled water at 4c for use in this study 
 within 3 months following extraction . the crowns of the teeth were cut perpendicular to the long axis of the root at the 
 cement - enamel junction with a diamond coated disk at slow speed with constant 
 water - cooling . root canals were instrumented using the step back technique to obtain a 
 flared preparation . in all teeth , the working length was determined visually by 
 subtracting 1 mm from the length of a # 10 k - file ( dentsply maillefer , ballaigues , 
 switzerland ) at the apical foramen . after each step in the flare preparation , the canal was 
 irrigated with 2.5% sodium hypochlorite during 1 min . then , 17% edta was used as a final 
 irrigant for 1 min , after a rinse of distilled water ( 1 min ) to remove any remnants of 
 the irrigating solutions . the roots were randomly divided into three equal groups ( n=20 ) according to the root 
 canal sealer used ; g1 : ah plus ( dentsply maillefer , ballaigues , switzerland ) , g2 : 
 endorez ( ultradent products , inc . , south jordan , utah , usa ) and g3 : realseal ( sybron 
 endo , glendora , ca , usa ) . for the group filled with ah plus , the sealer was mixed using ah plus jet mixing system , 
 and then introduced into the root canal orifices with the intraoral tip . a 40.02 taper 
 master gutta - percha cone was placed into the canal and then the canal was filled up 
 using the cold lateral condensation technique and accessory gutta - percha points size # 25 
 and # 20 dipped in a small amount of sealer . endorez was mixed in an ultra - mixer and dispensed using a narrow diameter syringe ( skini 
 syringe ) ( ultradent products inc . , south jordan , utah , usa ) with a fine - tipped cannula 
 navi tip ( ultradent products , inc . roots were filled totally 
 with endorez sealer . then a 40.02 resin coated gutta - percha cone ( endorez point ) 
 ( ultradent products , , south jordan , utah , usa ) was placed inside the canal , and 
 additional endorez points size # 25 and # 20 were placed into the canal using the cold 
 lateral condensation technique . for the group filled with realseal , realseal primer ( sybronendo , glendora , ca , usa ) was 
 introduced into the root canal with a paper point ( roeko , langenau , germany ) soaked with 
 the primer for the apical region . the primer was placed into the middle and coronal part 
 using a micro brush ( microbrush international , grafton , wi , usa ) . the sealer was dispensed directly from the 
 tip of its auto mix dual - chamber syringe , according to the manufacturer 's instructions . a 40.02 taper realseal master point was placed into the canal and then additional 
 realseal accessory points size # 25 and # 20 were placed into the canal using the cold 
 lateral condensation technique . in all specimens , the excess of points was removed with a hot instrument and the 
 remainder was condensed vertically . they were resected at the apex perpendicular to the 
 long axis of the tooth until 10 mm of root length was obtained . each root was 
 transferred to a test tube ( eppendorf ibrica , madrid , spain ) and stored in a humidifier 
 at 37c for 24 hours to complete sealer setting . finally , each sealer group ( n=20 ) was randomly divided into two subgroups according to 
 tests applied ( n=10 for push - out test and n=10 for fluid filtration test ) . the external root surfaces of subgroups for the fluid filtration test were covered 
 with a layer of nail varnish leaving the coronal and apical orifices open . the 
 specimens were attached to a device to measure the permeability by fluid transport 
 described by pashley , et al . the roots were inserted into a silicon tube ( 2 mm internal diameter ) , and 
 attached with cyanoacrylate glue on the outer surface of the tube . a pressure tank of 
 250 ml of distilled water was placed 100 cm higher than the root to create a pressure 
 of 100 cm h2o . a 10 ml micropipette was inserted and attached with 
 cyanoacrylate glue to measure movement of the air bubble introduced into the system 
 with a micro syringe . the volume of fluid transport was measured by observing the movement of 
 air bubbles within a 10 ml micropipette at 24 hours . previously , the system was sealed and checked for 10 min to ensure there was no 
 leakage . the root was covered with water and then covered with a plastic dish to 
 prevent evaporation . each specimen was attached to the device , and then the system 
 was bled by opening the joint between the water reservoir and the specimen . the air 
 bubble was then aligned with the zero point of the 10 ml scale . permeability was 
 measured as the distance that the bubble had moved by the end of 24 hours . this 
 measurement showed the amount of fluid which had permeated through the root filling 
 in l . a test was done with two additional roots , covering the apex with two layers 
 of nail varnish , to ensure that there was no leakage or fluid movement anywhere 
 within the device . ten roots for each group were cut into four slices 1 mm thick , from cervical to 
 apical direction ( cervical1 [ c1 ] , cervical2 [ c2 ] , middle1 [ m1 ] , middle2 [ m2 ] ) , using 
 a 300 m thick sintered diamond wafering blade perpendicular to the long axis of the 
 root canal at low speed with constant water cooling . the thickness of each root slice 
 was assessed by means of a digital caliper . each slice was subjected to compressive 
 loading via a universal testing machine ( instron 3345 , instron ltd , high wycombe , uk ) 
 equipped with a 0.5 mm - diameter cylindrical plunger . the plunger was positioned so 
 that it only touched the root filling on loading , without touching the canal wall or 
 introducing shear stress along the interfaces . thus , the side with the smaller 
 diameter of the root canal faced upwards and was aligned with the shaft that would 
 exert pressure load on the filling ( apical - coronally ) until the filling was 
 displaced . the machine was calibrated at a constant speed of 0.5 mm / min , and the 
 maximum failure load was recorded in newton ( n ) . failure was shown by the extrusion 
 of the intact cone of root filling from the root slice and affirmed by the appearance 
 of a sharp drop along the load / time curve recorded by the testing machine . the 
 computer and software attached to the universal testing machine calculated the 
 push - out bond strength value for each specimen , and converted them into mpa by 
 dividing the applied load by the bonded area . the slices were examined under a stereomicroscope at 40x magnification to determine 
 modes of failure : adhesive at filling material with dentin interface , cohesive within 
 filling material , or mixed failure . the normality of the data distribution in all the study groups was verified by 
 applying the shapiro - wilk test , and levene 's test was used to explore the homogeneity 
 of variance among groups . fluid movement values at 24 hours were compared among the three different sealers and 
 filling materials by means of one - way anova and tukey 's tests . to analyze push - out bond strength values , an anova for repeated measures was first 
 applied to explore the influence of the root level ( within - subject factor ) and 
 sealers / filling material ( between - subjects factor ) on the push - out bond strength to 
 root walls . as the sample groups did not fulfill homoscedasticity requirements , 
 non - parametrical tests were used to compare push - out bond strength values among 
 materials ( kruskal - wallis ' and mann - whitney 's u test ) and root levels ( friedman 's 
 tests for multiple comparisons and wilcoxon 's rank tests , for pairwise 
 comparison ) . the chi test was used to analyze the mode of failure distribution among 
 groups . the external root surfaces of subgroups for the fluid filtration test were covered 
 with a layer of nail varnish leaving the coronal and apical orifices open . the 
 specimens were attached to a device to measure the permeability by fluid transport 
 described by pashley , et al . the roots were inserted into a silicon tube ( 2 mm internal diameter ) , and 
 attached with cyanoacrylate glue on the outer surface of the tube . a pressure tank of 
 250 ml of distilled water was placed 100 cm higher than the root to create a pressure 
 of 100 cm h2o . a 10 ml micropipette was inserted and attached with 
 cyanoacrylate glue to measure movement of the air bubble introduced into the system 
 with a micro syringe . the volume of fluid transport was measured by observing the movement of 
 air bubbles within a 10 ml micropipette at 24 hours . previously , the system was sealed and checked for 10 min to ensure there was no 
 leakage . the root was covered with water and then covered with a plastic dish to 
 prevent evaporation . each specimen was attached to the device , and then the system 
 was bled by opening the joint between the water reservoir and the specimen . the air 
 bubble was then aligned with the zero point of the 10 ml scale . permeability was 
 measured as the distance that the bubble had moved by the end of 24 hours . this 
 measurement showed the amount of fluid which had permeated through the root filling 
 in l . a test was done with two additional roots , covering the apex with two layers 
 of nail varnish , to ensure that there was no leakage or fluid movement anywhere 
 within the device . ten roots for each group were cut into four slices 1 mm thick , from cervical to 
 apical direction ( cervical1 [ c1 ] , cervical2 [ c2 ] , middle1 [ m1 ] , middle2 [ m2 ] ) , using 
 a 300 m thick sintered diamond wafering blade perpendicular to the long axis of the 
 root canal at low speed with constant water cooling . the thickness of each root slice 
 was assessed by means of a digital caliper . each slice was subjected to compressive 
 loading via a universal testing machine ( instron 3345 , instron ltd , high wycombe , uk ) 
 equipped with a 0.5 mm - diameter cylindrical plunger . the plunger was positioned so 
 that it only touched the root filling on loading , without touching the canal wall or 
 introducing shear stress along the interfaces . thus , the side with the smaller 
 diameter of the root canal faced upwards and was aligned with the shaft that would 
 exert pressure load on the filling ( apical - coronally ) until the filling was 
 displaced . the machine was calibrated at a constant speed of 0.5 mm / min , and the 
 maximum failure load was recorded in newton ( n ) . failure was shown by the extrusion 
 of the intact cone of root filling from the root slice and affirmed by the appearance 
 of a sharp drop along the load / time curve recorded by the testing machine . the 
 computer and software attached to the universal testing machine calculated the 
 push - out bond strength value for each specimen , and converted them into mpa by 
 dividing the applied load by the bonded area . the slices were examined under a stereomicroscope at 40x magnification to determine 
 modes of failure : adhesive at filling material with dentin interface , cohesive within 
 filling material , or mixed failure . the normality of the data distribution in all the study groups was verified by 
 applying the shapiro - wilk test , and levene 's test was used to explore the homogeneity 
 of variance among groups . fluid movement values at 24 hours were compared among the three different sealers and 
 filling materials by means of one - way anova and tukey 's tests . to analyze push - out bond strength values , an anova for repeated measures was first 
 applied to explore the influence of the root level ( within - subject factor ) and 
 sealers / filling material ( between - subjects factor ) on the push - out bond strength to 
 root walls . as the sample groups did not fulfill homoscedasticity requirements , 
 non - parametrical tests were used to compare push - out bond strength values among 
 materials ( kruskal - wallis ' and mann - whitney 's u test ) and root levels ( friedman 's 
 tests for multiple comparisons and wilcoxon 's rank tests , for pairwise 
 comparison ) . the chi test was used to analyze the mode of failure distribution among 
 groups . the ah plus / gutta - percha group showed the highest value and the 
 realseal group the lowest value , though there were no significant differences among 
 the three sealer / core materials . this study makes manifest that all the materials 
 used allowed fluid to flow along the root canal twenty four hours after filling . mean values and standard deviation of permeability ( l/24 h ) descriptive statistics of the push - out bond strength are given in table 2 . means and standard ( mpa ) deviations of push - out bond strength test . different letters indicate significant differences in push - out strength 
 values among root levels , for each material and for the whole sample different letters indicate significant differences in push - out 
 strength values among root levels , for each material and for the whole 
 sample   anova for repeated measures demonstrated that root level ( f=27.148 , p<0.001 ) , and 
 the interaction between the root level and sealer / core material ( f=8.66 , p=0.001 ) , 
 significantly affect the push - out bond strength to the walls of the root canal . the 
 sealer / core material in itself does not significantly influence the push - out bond 
 strength values ( f=2.492 ; p=0.102 ) . for the whole sample , statistically significant differences were detected with 
 respect to the root level ( friedman 's test , chi=23.93 ; p<0.001 ) . pairwise comparisons gave differences among 
 all levels , with increased push - out values from cervical to apical except between m1 
 and m2 levels . when each material was considered separately , ah plus / gutta - percha also demonstrated 
 significant differences according to root level , obtaining the lowest values in slice 
 c1 . for realseal system , the push - out bond strength increases apically , with 
 c1c2m1=m2 . endorez system showed a similar behavior at all root levels 
 ( chi=3.54 ; p=0.315 ) . push - out values of the three sealing systems were also compared in each level . levels c1 and c2 showed no differences in terms of sealer / core materials , but there 
 were differences between sealers at deeper levels : m1 and m2 . realseal demonstrated 
 greater bond strength than endorez at m1 level ( u=21.00 ; p=0.028 ) . at m2 level , 
 endorez showed a significantly lesser bond strength than ah plus ( u=22.00 ; p=0.034 ) 
 and realseal ( u=13.00 ; p=0.005 ) ( figure 1 ) . bar chart showing push - out bond strength values and comparisons among 
 sealer / core materials in each root level ( mann - whitney 's u test ) * significant differences among endorez and real seal at m1 level # siginificant differences at m2 level : endorez push - out was significantly 
 lesser than the rest of sealer / core materials the predominating type of failure for all three sealer / core materials tested was 
 adhesive failure , followed by mixed type failures . for the whole sample , this 
 distribution was similar among the three sealers used ( chi=2.45 , p=0.65 ) , and the four root levels 
 ( chi=4.66 , p=0.58 ) ( table 
 3 ) . failure mode . different letters indicate significant differences in 
 push - out strength values among root levels , for each material and for the 
 whole sample the ah plus / gutta - percha group showed the highest value and the 
 realseal group the lowest value , though there were no significant differences among 
 the three sealer / core materials . this study makes manifest that all the materials 
 used allowed fluid to flow along the root canal twenty four hours after filling . means and standard ( mpa ) deviations of push - out bond strength test . different letters indicate significant differences in push - out strength 
 values among root levels , for each material and for the whole sample different letters indicate significant differences in push - out 
 strength values among root levels , for each material and for the whole 
 sample   anova for repeated measures demonstrated that root level ( f=27.148 , p<0.001 ) , and 
 the interaction between the root level and sealer / core material ( f=8.66 , p=0.001 ) , 
 significantly affect the push - out bond strength to the walls of the root canal . the 
 sealer / core material in itself does not significantly influence the push - out bond 
 strength values ( f=2.492 ; p=0.102 ) . for the whole sample , statistically significant differences were detected with 
 respect to the root level ( friedman 's test , chi=23.93 ; p<0.001 ) . pairwise comparisons gave differences among 
 all levels , with increased push - out values from cervical to apical except between m1 
 and m2 levels . when each material was considered separately , ah plus / gutta - percha also demonstrated 
 significant differences according to root level , obtaining the lowest values in slice 
 c1 . for realseal system , the push - out bond strength increases apically , with 
 c1c2m1=m2 . endorez system showed a similar behavior at all root levels 
 ( chi=3.54 ; p=0.315 ) . push - out values of the three sealing systems were also compared in each level . levels c1 and c2 showed no differences in terms of sealer / core materials , but there 
 were differences between sealers at deeper levels : m1 and m2 . realseal demonstrated 
 greater bond strength than endorez at m1 level ( u=21.00 ; p=0.028 ) . at m2 level , 
 endorez showed a significantly lesser bond strength than ah plus ( u=22.00 ; p=0.034 ) 
 and realseal ( u=13.00 ; p=0.005 ) ( figure 1 ) . bar chart showing push - out bond strength values and comparisons among 
 sealer / core materials in each root level ( mann - whitney 's u test ) * significant differences among endorez and real seal at m1 level # siginificant differences at m2 level : endorez push - out was significantly 
 lesser than the rest of sealer / core materials the predominating type of failure for all three sealer / core materials tested was 
 adhesive failure , followed by mixed type failures . for the whole sample , this 
 distribution was similar among the three sealers used ( chi=2.45 , p=0.65 ) , and the four root levels 
 ( chi=4.66 , p=0.58 ) ( table 
 3 ) . different letters indicate significant differences in 
 push - out strength values among root levels , for each material and for the 
 whole sample in this study , permeability and push - out bond strength were compared among roots 
 treated endodontically with ah plus , endorez and realseal sealers and root canals filled 
 using lateral condensation technique at 24 hours . the results showed that the 
 permeability and global push - out bond strength is not affected by the kind of 
 sealer / core material . microleakage studies are most commonly used to measure the ex vivo 
 sealing ability of a root canal filling , though various methods have been proposed or 
 recommended for evaluation of leakage . in this study , an endodontic fluid transport model was chosen to 
 evaluate the sealing ability of three different root canal sealers , in view of its 
 advantages : the samples are not destroyed , it provides quantitative measurement , and the 
 results are precise , as small volumes can be recorded . we used different samples for fluid 
 filtration and push - out bond strength , to be performed at exactly 24 hours ' time , thus 
 avoiding different degrees of conversion for the sealers . we did not light - cure the 
 coronal portion of the realseal sealer as recommend by manufacturer 's instruction , 
 because fast - setting light - cured resin sealers produce restriction in the flow and 
 consequent defects or weakening of bond strength . moreover , the slow chemical reaction of methacrylate - based 
 self - etching sealers may reduce shrinkage stress by means of prolonged plastic flow 
 during the setting time of the material . we held that such behavior would allow for complete resin 
 infiltration into the demineralized dentin . our results showed that there were no statistically significant differences in the 
 values of fluid filtration among the three sealers used in the study . it is noteworthy , 
 however , that none of the investigated sealers / core materials achieved a tight seal at 
 the filling - cement - root interface , a point also brought out by vasconcelos , et 
 al . ( 2011 ) , allowing fluid to 
 flow along the filled root canal twenty - four hours after filling , whereas the control 
 showed no filtration . currently , the clinical relevance of leakage tests in 
 vitro has been questioned , because it is difficult to interpret results when , in our opinion , 
 only zero filtration can be considered a good result . moreover , there is no correlation 
 among various methods to evaluate microleakage , and the outcome of the tests depends on 
 the evaluation method . in the absence of correlation between 
 the ex vivo sealing ability of root filled teeth and " clinical 
 success " , we believe there is 
 a threshold for microleakage values that would prove clinically relevant . the adhesion tests of methacrylate bond sealer to dentin have not yet been standardized . 
 the push - out test seems to be more reliable because it allows for adequate 
 standardization of the specimens , the absence of premature failures and the variability 
 of data distribution , while supplying a better estimation of the actual bonding 
 effectiveness . in all of the 
 studies reviewed , biomechanical preparation is done with mechanical instrumentation 
 because it is easier to perform and provides a more appropriate standardization of root 
 canals . we used the step back technique and lateral condensation because it is still 
 widely used throughout the world ; moreover , there is no study of endodontic sealer 
 adhesion and push - out , because the small final diameter of the canal makes the 
 push - out test more difficult to perform . in this study , we used three totally different kinds of sealers : a conventional 
 nonbonding epoxy resin - based sealer , ah plus ; a first generation non - acidic diurethane 
 dimethacrylate and triethyleneglycol dimethacrylate , endorez ; and a second generation 
 sealer , realseal , based on adhesive technology with a self - etching primer and in 
 association with a thermoplastic synthetic polyester polymer - based root canal filling 
 material . it should be noted that the conventional nonbonding ah plus / gutta - percha root 
 filling was equal to realseal and endorez . ( 2006 ) , who 
 found that the epiphany / resilon combination was not superior to the ah plus / gutta - percha 
 combination . still , most studies report that ah plus sealer presents greater adhesion to 
 dentin than realseal , regardless of root canal wall treatment . clinicians need to be aware that methacrylate 
 resin - based sealers did not meet expectations regarding adhesion to root dentin , and , at 
 this point in their development , there are no clear benefits in their use . the push - out bond strength results were significantly influenced by dentin location . ah 
 plus and realseal obtained higher values in the deeper slices , while endorez showed the 
 lowest values , regardless of location . all sealers exhibited their low push - out bond 
 strength values in two superficial slices . this can be explained by the presence of 
 oxygen , inhibiting sealer setting and producing a layer with low polymerization . because we adopted a clinical approach , we were not able to ascertain whether an 
 increase of the adhesive strength to the apex will remain in the most apical sections . manual instrumentation until 40 iso width produce very limited widening of the canal in 
 the apical section , making it impossible to perform push - out tests without values 
 having a frictional component with the canal walls . previous authors have tested apices , 
 but no realistic enlargements were made regarding canal preparation with drills for a 
 post or using a tapered diamond 
 bur . the values of the push - out test are very low , consistent with results of other studies 
 using the same methodology , indicating that the bonding of two methacrylate resin - based 
 sealers and root dentin is much weaker than with resin - dentin bonds , 25 - 30 mpa . furthermore , the adhesive failures 
 between sealer / dentin interface clearly suggest an inadequate level of adhesion between 
 sealer and dentin in terms of bond strength . this may be due to the difficulties in testing 
 materials with great plasticity , such as gutta - percha , realseal and endorez points ; in 
 contrast , when the test was done with sealer and no core material , values were 
 higher , suggesting failure may be traced to the sealer / material 
 interface . in a root canal there is a highly unfavorable configuration factor ( ratio of 
 bonded to unbounded resin surfaces ) 
 that contributes to maximizing the polymerization stress of resin - based materials along 
 the root canal walls ; this may even exceed the bond strength of dentin adhesives to 
 dentin , resulting in gap formation along the surfaces . ( 2012 ) report that there is a 
 correspondence between the presence of gaps and microleakage . despite the material 's relatively low bond strength to root dentin the main 
 problem is that this low push - out bond strength is accompanied by fluid filtration . the 
 adhesion of resin sealer to gutta - percha or core seems to play an important role in 
 microleakage prevention , since it does not have to be at the sealer - dentin interface . microleakage can affect the bonding of sealers to dentin by plasticization ( fluids are 
 absorbed by resins ) and hydrolysis 
 due to water entry in the interface . in addition , collagen degradation may occur due to 
 host - derived matrix metalloproteinases ( mmps ) in dentin that are slowly released over 
 time when self - etching adhesives are used . realseal may therefore adversely affect the longevity of bonded 
 root canal fillings by accelerating degradation of the bond through the movement of 
 fluid between the hybrid layer and unaffected dentin . this study reveals that global push - out bond strength and permeability were not 
 affected by different sealer / core materials : this leads us to partially accept the null 
 hypothesis , because in the two deeper slices , realseal and ah plus achieved higher 
 push - out bond strength than endorez . we can not confirm any clear relationship between 
 permeability and push - out bond strength . this study makes manifest that ah plus / gutta - percha , endorez and realseal systems 
 allowed fluid to flow along the filled root canal in the twenty - four hours after 
 filling . no significant differences were found among global push - out bond strengths of 
 the three sealers / filling materials ; but there does exist a regional influence , by which 
 the push - out strength achieved with realseal and ah plus to intraradicular dentin was 
 found to be greater in the medium root slices .
objectivesto investigate the bond strength and seal ability produced by ah 
 plus / gutta - percha , endorez and realseal systems to root canal dentin . 
 material and methodssixty extracted single - root human teeth , instrumented manually to size 40 , were 
 divided into three groups ( n=20 ) according to the sealer used ; g1 : ah plus , g2 : 
 endorez , and g3 : realseal sealers . 
 after filling using the lateral condensation 
 technique , each sealer group was randomly divided into two subgroups according to 
 the tests applied ( n=10 for push - out test and n=10 for fluid filtration test ) . 
 a 
 fluid filtration method was used for quantitative evaluation of apical leakage . 
 four 1-mm - thick slices ( cervical and medium level ) were obtained from each root 
 sample and a push - out test was performed . 
 failure modes were examined under 
 microscopy at 40x , and a one - way anova was applied to analyze the permeability . 
 non - parametrical statistics for related ( friedman 's and wilcoxon 's rank tests ) or 
 unrelated samples ( kruskal - wallis ' and mann - whitney 's tests ) allowed for 
 comparisons of push - out strength values among materials at the different levels . 
 statistical significance was accepted for p values < .05 . 
 resultsthere are no significant differences among fluid filtration of the three sealers . 
 the sealer / core material does not significantly influence the push - out bond 
 strength values ( f=2.49 ; p=0.10 ) , although statistically significant differences 
 were detected with regard to root level ( chi2=23.93 ; p<0.001 ) . 
 ah 
 plus and realseal obtained higher bond strength to intraradicular dentin in the 
 medium root slices . 
 conclusionsthere are no significant differences between the permeability and global push - out 
 bond strength to root canal dentin achieved by ah plus / gutta - percha , endorez and 
 realseal systems .