endodontic surgery has advanced in recent years to increase the clinician 's ability to achieve more predictably successful clinical outcomes .
the properties of a root - end filling material are very critical in determining the success of periradicular surgery .
, to address the shortcomings of commonly used root - end filling materials . in a clinical study , saunders et al . , demonstrated that use of mta as a root - end filling material results in a high success rate but extended setting time and difficulties in handling mta resulted in limited use in many surgical situations .
also the set mta contains many voids in the form of air bubbles , pores , and capillary channels , which could affect the apical seal obtained with mta .
recently a new calcium alumino silicate cement has been developed by septodont called biodentine with excellent biocompatibility , increased physico - chemical properties like short setting time and high mechanical strength , which makes it clinically easy to handle for endodontic cases and dentin restorative procedures .
some investigations have focused on its removal while others have considered its effects on apical and coronal microleakage , bacterial penetration of the tubules , and the adaptation of root - end filling materials .
irrigation with doxycycline to remove the smear layer from dentinal surfaces has been shown to improve the apical seal of root - end filling materials , such as irm and amalgam .
mtad ( a mixture of tetracycline , acid and a detergent ) has been the focus of attention as an alternative root canal irrigant .
use of mtad has been reported to be more efficient in removing smear layer as compared with the use of edta and naocl , especially from the apical third without significantly changing the structure of the dentinal tubules .
, there has been no study investigating the use of mtad as an irrigant in root - end cavities .
hence the present study was designed to assess the apical seal , obtained after root - end cavity irrigation with mtad and retrograde filling with different restorative materials  mta and biodentine .
sixty freshly extracted human maxillary central incisors with mature root apices and single canal were selected and stored in 10% formalin solution until further use . teeth with gross caries involving the root , cracks on the root surface , and exceptionally short and thin roots were excluded .
all the teeth were decoronated at the length of 14 mm from the apex with the help of diamond disc under copious water irrigation .
the working length was established and the root canals were instrumented with protaper rotary files ( dentsply tulsa dental , tulsa ) using x - smart rotary device ( dentsply maillefer ) .
instrumentation was done till f4 file with 2.5% naocl irrigation between each file instrumentation . ah plus sealer ( dentsply caulk , milford , de ) was mixed according to manufacturer 's instructions and was inserted into the canal with the help of lentulospirals .
protaper gutta - percha cone ( dentsply maillefer ) was used for obturation using lateral condensation technique and accessory cones used if required . the coronal opening for
the apical 3 mm of all the teeth were resected with a round diamond point in a water - cooled , high - speed hand - piece .
root - end preparations were made to a depth of 3 mm using proultra surgical tip no 2 ( dentsply maillefer ) .
thirty root - end preparations were irrigated with mtad ( biopure , dentsply , tulsa dental ) for 5 min ( group a ) , while 30 were irrigated with saline ( parenteral surgicals , india ) for 5 min ( group b ) prior to placement of root - end filling .
samples under each subgroup were then filled either with mta ( pro - root mta , dentsply , tulsa dental ) ( 1a and 2a ) or biodentine ( septodont , usa ) ( 1b and 2b ) and placed according to manufacturer 's instructions .
all teeth received a final 1 min rinse with saline after root - end filling .
the teeth were wrapped in moist gauze and stored in a sealed container at 37c for a minimum of 1 week .
samples from all the groups were coated with two coats of nail varnish except on the apical 3 mm .
after the application of nail varnish , the samples were dried and immersed in 5 ml of 2% methylene blue dye ( s d fine chemical ltd , india ) in 15 ml screw - capped bottle and stored at 37c  2c , at relative humidity in incubator for 72 hours .
after 72 hours , the samples were then washed under running tap water to remove the traces of the dye .
the teeth were then immersed and stored in freshly prepared 35% nitric acid ( s d fine chemical ltd , india ) for 72 hours in the centrifugal tube .
after 72 hours , the solutions were filtered using a fine grit filter paper in another centrifugal tube and the obtained sample solutions were centrifuged at 2000 rpm for one minute . the supernatant solutions thus collected were used to determine absorbency in a uv visible spectrophotometer at 670 nm .
the data was analyzed statistically by comparison of mean microleakage and t - test using spss 20 software .
all the teeth were decoronated at the length of 14 mm from the apex with the help of diamond disc under copious water irrigation .
the working length was established and the root canals were instrumented with protaper rotary files ( dentsply tulsa dental , tulsa ) using x - smart rotary device ( dentsply maillefer ) .
ah plus sealer ( dentsply caulk , milford , de ) was mixed according to manufacturer 's instructions and was inserted into the canal with the help of lentulospirals .
protaper gutta - percha cone ( dentsply maillefer ) was used for obturation using lateral condensation technique and accessory cones used if required .
the apical 3 mm of all the teeth were resected with a round diamond point in a water - cooled , high - speed hand - piece .
root - end preparations were made to a depth of 3 mm using proultra surgical tip no 2 ( dentsply maillefer ) .
thirty root - end preparations were irrigated with mtad ( biopure , dentsply , tulsa dental ) for 5 min ( group a ) , while 30 were irrigated with saline ( parenteral surgicals , india ) for 5 min ( group b ) prior to placement of root - end filling .
samples under each subgroup were then filled either with mta ( pro - root mta , dentsply , tulsa dental ) ( 1a and 2a ) or biodentine ( septodont , usa ) ( 1b and 2b ) and placed according to manufacturer 's instructions .
all teeth received a final 1 min rinse with saline after root - end filling .
the teeth were wrapped in moist gauze and stored in a sealed container at 37c for a minimum of 1 week .
samples from all the groups were coated with two coats of nail varnish except on the apical 3 mm . after the application of nail varnish , the samples were dried and immersed in 5 ml of 2% methylene blue dye ( s d fine chemical ltd , india ) in 15 ml screw - capped bottle and stored at 37c  2c , at relative humidity in incubator for 72 hours .
after 72 hours , the samples were then washed under running tap water to remove the traces of the dye .
the teeth were then immersed and stored in freshly prepared 35% nitric acid ( s d fine chemical ltd , india ) for 72 hours in the centrifugal tube .
after 72 hours , the solutions were filtered using a fine grit filter paper in another centrifugal tube and the obtained sample solutions were centrifuged at 2000 rpm for one minute . the supernatant solutions thus collected were used to determine absorbency in a uv visible spectrophotometer at 670 nm .
the data was analyzed statistically by comparison of mean microleakage and t - test using spss 20 software .
results suggest a significant difference ( p < 0.005 ) between group 1a ( mtad irrigation followed by mta placement ) and 2a ( saline irrigation followed by mta placement ) .
there was also a significant difference ( p < 0.1 ) between the groups 1b ( mtad irrigation followed by biodentine placement ) and 2b ( saline irrigation followed by biodentine placement ) .
there was a significant difference ( p < 0.005 ) between group 1a ( mta ) and 1b ( biodentine ) with mtad irrigation and also between group 2a ( mta ) and 2b ( biodentine ) with saline irrigation .
improved apical seal of root - end fillings has been pursued in an effort to improve the clinical results of apical surgery . surgical smear layer in endodontics
is defined as a smear layer , which contains micro - organisms and necrotic pulpal tissues which is formed on the dentinal surfaces , cut by the instruments during apicoectomy and retrograde cavity preparation .
citric acid , edta , 35% orthophosphoric acid and biopure mtad ( dentsply tulsa dental ) have been recommended for the removal of surgical smear layer .
smear layer removal from retrograde cavity preparation and dentin demineralization by the acidic agent of mtad i. e. , citric acid , has been shown to be associated with more rapid and complete cementum deposition on the root end , which produces rapid dentoalveolar healing .
doxycycline is a potent antibiotic and the long lasting substantivity of doxycycline on root surfaces supports the concept of using resected root surfaces as a substrate for the deposition and slow release for local doxycycline delivery .
mta has been considered as the material of choice as a root - end filling material .
nonetheless , mta does not provide a hermetic seal and it has been reported that fluid flow occurs at the material to the tooth interface .
recently , a novel biomaterial called biodentine has been introduced , and it has been shown that it can replace the traditional mta . in the present study ,
the results were recorded as a measure of absorbance of light . according to the beer - lamberts law ,
the absorbency of the solution is directly proportional to the concentration of absorbing species in the solution and path length .
thus for a fixed path length , uv visible spectroscopy can be used to determine the concentration of the absorber in the solution .
hence it can be interpreted that absorbance of the solution is directly related to the amount of microleakage .
the study utilizes a dye extraction method to quantify the amount of apical microleakage instead of dye penetration study as it has been shown that the depth of penetration of the dye is not uniform around the margins of a restoration and gives randomly chosen results , raising doubts about their reliability .
dye extraction method provides reliable results because it measures all of the dye taken up in the root and gives a quantitative reading .
the current investigation suggests that the removal of smear layer with mtad decreases the apical sealing ability of mta and improves the apical sealing ability of biodentine .
the results of the present study with regard to mta are in agreement with the findings of kubo et al . , who demonstrated demineralizing agents had a negative effect on the apical seal of mta when placed in a retrograde ( surgical ) model .
decreased leakage in smeared versus smear free mta obturated root end cavities might have been due to several factors , such as hydrophilic properties of mta and particle size of mta . the smear layer might act as a  coupling agent  enhancing the bond between the mta and root canal dentin due to hydraulic nature of mta which sets in the presence of moisture . the moist environment caused by the smear layer
might have a positive effect on the adaptation of mta to the root canal wall .
komabayashi and spngberg reported that the cumulative percentage of particles between 1.5 - 3 m was 70% for gray proroot mta .
garberoglio and brnnstrm showed that the tubule diameter was 0.9 - 2.5 m at different levels of the root canal in a scanning electron microscopy study .
consequently , the particle size of mta might not be suitable for penetration into the tubules .
the apical seal was reduced in root end cavity specimens filled with mta wherein the root end cavity irrigation was preceded with mtad which may be due to the ability of citric acid present in mtad to remove smear layer from dentinal surfaces .
the findings of the present study revealed that biodentine provided a better apical seal following mtad irrigation . in an earlier study by han and okiji , representative scanning electron microscope images and confocal images of biodentine samples showed tag - like structures within the dentinal tubules just beneath the interface which is due to the calcium and silica ion uptake into the dentine .
biodentine samples also showed an interfacial layer within the structure of dentin , just beneath the cement which is termed as 
mineral infiltration zone  ( miz ) and is associated with an altered intertubular micro - structure .
the dentinal tubules in the surfaces exposed to biodentine , appeared blocked and did not open to the surface , unlike the tubules in the clean , unexposed surfaces which explains its excellent sealing ability .
following hydration , the flowable consistency of the biodentine aids its penetration through opened dentinal tubules to crystallize over time within their structure , participating in the mechanical properties of the interface .
hence the removal of smear layer followed by biodentine placement facilitates the bonding to the exposed dentinal tubules .
the present study showed that biodentine produced less amount of microleakage compared to mta and the removal of smear layer improved the sealing ability of biodentine .
biodentine causes the uptake of calcium and silica in the adjacent root canal dentin in the presence of physiological solution .
biodentine has tricalcium silicate and zirconium particles of finer particle size , thus a higher value for specific surface area .
the rate of reaction of tricalcium silicate was higher for biodentine than mta owing to its optimized particle size distribution , the presence of calcium carbonate ( caco3 ) and the use of calcium chloride ( cacl2 ) . the interfacial layer formed between biodentine and dentine
it appears that the adhesion of biodentine cement to dentin may result from the physical process of crystal growth within the dentinal tubules leading to micromechanical bonding .
the removal of the loosely attached smear layer from the cavity surfaces with subsequent opening of dentinal tubules and demineralization of dentin creates a retentive surface for interlocking of restoratives .
within the limitations of the present study , it can be concluded that mta filled root - end cavities were more susceptible to microleakage after root - end irrigation with mtad , whereas the same mtad when used with biodentine significantly improved the apical seal of root - end cavities .
also the apical seal obtained with biodentine was superior to that obtained with mta irrespective of the presence of smear layer .
thus a regimen involving irrigation of the root - end cavity with mtad followed by retrofilling with biodentine can enhance the apical seal and augment osseous healing along with a sustained antibacterial effect , thus improving the success of periradicular surgery [ table 1 ] .
comparison between the mean micro leakage of mta and biodentine when used with mtad and saline
 introduction : the present study is designed to assess the apical seal obtained after root end cavity irrigation with mtad and retrograde filling with mineral trioxide aggregate ( mta ) and biodentine.materials and methods : sixty extracted maxillary central incisors were instrumented and obturated . 
 apical 3 mm of all the roots were resected and retrograde preparations of 3 mm were made in all the teeth using ultrasonic tips . 
 thirty root end preparations were irrigated with mtad for 5 min ( group 1 ) , while 30 were irrigated with saline for 5 min ( group 2 ) . 
 each main group was subdivided into two subgroups containing 15 samples each . 
 samples under each subgroup were then filled either with mta ( 1a and 2a ) or biodentine ( 1b and 2b ) . 
 the amount of microleakage was assessed using a uv spectrophotometer.results:statistical analysis suggest a significant difference ( p < 0.005 ) between group 1a and 2a and between the groups 1b and 2b 
 ( p < 0.1 ) 
 . there was a significant difference ( p < 
 0.005 ) between group 1a and 1b and also between group 2a and 2b.conclusion:irrigation with mtad significantly improved the apical seal of biodentine , but it increased the microleakage in mta - filled root end cavities . also the apical seal obtained with biodentine was superior to that obtained with mta . 
INTRODUCTION
MATERIALS AND METHODS
Specimen preparation
Division of groups
Specimen preparation using dye extraction study for UV spectrophotometer analysis
RESULTS
DISCUSSION
CONCLUSION