radicular lesions develop only when root canals are exposed to the oral flora , and the root canal system has the capacity to harbor several species of bacteria as well as their toxins and by products . engress of these irritants from the root canal system into radicular tissues results in the formation of radicular lesions . because of the complexity of the root canal system and the difficulty to completely clean it using the present techniques and instruments , root canals can not always be adequately treated using a non - surgical orthograde approach . when non - surgical attempts prove unsuccessful or are contraindicated , surgical endodontic therapy is needed to save the tooth . the procedure usually comprises of exposure of the involved apex , resection of the apical end of the root , preparation of a class i cavity and insertion of a root end filling material . dental material development is fundamental to the improvement of clinical outcomes in dentistry . along with advancements in equipment technology , procedural improvements and therapeutic knowledge , the integration of these new materials into clinical practice can open treatment horizons that would have been otherwise impossible to envision . an ideal root end filling material should adhere and adapt to the dentinal walls of the root end preparation , should prevent leakage of microorganisms and their by - products into the periradicular tissues , should be biocompatible , should be insoluble in oral tissue fluids , should be dimensionally stable and should not be affected by the presence of moisture . mineral trioxide aggregate ( mta ) is now the gold standard among all root end filling materials . however , mta has certain drawbacks such as difficulty in handling and very slow setting reaction , which might contribute to leakage , surface disintegration , loss of marginal adaptation and continuity of the material . two new materials that might potentially provide the necessary properties of a root end filling material , polymethylmethacrylate ( pmma ) bone cement and calcium phosphate bone cement ( chitra cpc ) , were compared with mta in the present study with regard to its sealing ability using rhodamine b fluorescent dye and confocal laser scanning microscope . besides this , the study also compared the seal of root ends prepared using an ultrasonic retroprep tip and an er : yag laser . eighty sound , caries - free , mandibular premolars with single canals were shaped up to size 50 k file and obturated with gutta - percha and ah plus sealer . after removal of 2 mm of the filling material , the access cavity was sealed with light - cured glass ionomer cement . apical root resection was then performed by removing 3 - 4 mm of the apex at 90 to the long axis of the root with a straight fissure bur in a high - speed handpiece with water coolant . the teeth were randomly allocated into two control groups of 16 teeth each and experimental groups of 48 teeth each . in half of the samples , the apical cavity was prepared using an ultrasonic retropreparation diamond tip ( sybronendo ; bk3-r ) with water coolant . in the rest of the samples , apical cavity preparation was performed using an er : yag hard tissue laser ( fidelis laser ; fotona [ 400 mj , 10 hz ] ) under copious irrigation with water to prevent charring of the samples . two coats of nail varnish was applied to the external surface of each root . to reduce the amount of dye penetration through the exposed dentinal tubules , the resected surfaces were sealed with a layer of scotchbond multipurpose adhesive ( 3 m espe ) followed by application of nail varnish . group i : mta ( angelus ) used as the root end filling material 
 ia : ultrasonic retroprep tip used for root end preparationib : er : yag laser used for root end preparation 
  ia : ultrasonic retroprep tip used for root end preparation ib : er : yag laser used for root end preparation group ii : pmma bone cement ( depuy , johnson and johnson ) used as root end filling material 
 iia : ultrasonic retroprep tip used for root end preparationiib : er : yag laser used for root end preparation 
  iia : ultrasonic retroprep tip used for root end preparation iib : er : yag laser used for root end preparation group iii : chitra cpc ( chitra cpc ; sri chitra tirunal institute for medical sciences and technology ) used as root end filling material 
 iiia : ultrasonic retroprep tip used for root end preparationiiib : er : yag laser used for root end prep 
  iiia : ultrasonic retroprep tip used for root end preparation iiib : er : yag laser used for root end prep group iv : negative control . in 16 teeth , the entire root surface was coated with two coats of nail polish to act as negative controls group v : positive control . the remaining 16 teeth were not filled with any root end filling material to act as positive controls . all the roots were wrapped in wet pieces of gauze and stored in 100% humidity for 24 h. the roots were then totally immersed in a solution of rhodamine b fluorescent dye for 24 h. using a diamond disc , each root was longitudinally sectioned into two halves . each specimen was then examined as to the adaptation of the root end filling material to the cavity walls , the presence and absence of gaps and voids and the extent of dye penetration using confocal laser scanning microscope and oil immersion objectives in conjunction with a green filter ( wavelength 546 nm ) . rhodamine b dye gave a red - orange fluorescence when excited with green light of 546 nm wavelength . the amount of dye penetration was measured in m using the zeiss lsm image browser software ( version 4.2.0.121 ) . statistical analysis was done using a one - way anova and a two - way anova , independent samples t - test and scheffers post hoc test using spss version 16 for windows . root end preparation done with ultrasonics ( a ) root end preparation done with laser ( b ) group i : mta ( mineral trioxide aggregate ) ; group ii : ( pmma , polymethylmethacrylate bone cement , ) group iii : chitra cpc ( calcium phosphate bone cement ) complete dye penetration was noted between gutta - percha and the dentinal walls in the positive control samples . all the three materials , namely mta , pmma bone cement and chitra cpc , showed microleakage . comparison of microleakage showed maximum peak value of 0.86 mm for mta , 0.24 mm for pmma bone cement and 1.37 mm for chitra cpc [ figure 1 ] . microleakage seen under clsm the mean microleage values , arranged in order , starting from the least to the maximum , were : group iv : negative control ( 0.0 ) < group ii pmma ( 0.2469 ) < group i mta ( 0.8619 ) < group iii chitra cpc ( 1.3738 ) < group v positive control ( 3.00 ) . anova was applied to test for any possibility of equality of mean among the categories . results of the test indicated that there was a  high significant difference  in the values among the five groups ( p = 0.0001 ) . the statistical significance is considered if p  0.05 . independent samples t - test was used for comparison between the subgroups of each group . there was no significant difference in the microleakage values between the subgroups in group i ( p = 0.07 ) and group ii ( p = 0.29 ) , while a significant difference was found in group iii ( p = 0.00 ) . although there was a difference in the microleakage between the samples prepared using ultrasonic and laser , the difference was not found to be statistically significant . root end preparation done with ultrasonics ( a ) root end preparation done with laser ( b ) group i : mta ( mineral trioxide aggregate ) ; group ii : ( pmma , polymethylmethacrylate bone cement , ) group iii : chitra cpc ( calcium phosphate bone cement ) complete dye penetration was noted between gutta - percha and the dentinal walls in the positive control samples . all the three materials , namely mta , pmma bone cement and chitra cpc , showed microleakage . comparison of microleakage showed maximum peak value of 0.86 mm for mta , 0.24 mm for pmma bone cement and 1.37 mm for chitra cpc [ figure 1 ] . microleakage seen under clsm the mean microleage values , arranged in order , starting from the least to the maximum , were : group iv : negative control ( 0.0 ) < group ii pmma ( 0.2469 ) < group i mta ( 0.8619 ) < group iii chitra cpc ( 1.3738 ) < group v positive control ( 3.00 ) . anova was applied to test for any possibility of equality of mean among the categories . results of the test indicated that there was a  high significant difference  in the values among the five groups ( p = 0.0001 ) . the statistical significance is considered if p  0.05 . independent samples t - test was used for comparison between the subgroups of each group . there was no significant difference in the microleakage values between the subgroups in group i ( p = 0.07 ) and group ii ( p = 0.29 ) , while a significant difference was found in group iii ( p = 0.00 ) . although there was a difference in the microleakage between the samples prepared using ultrasonic and laser , the difference was not found to be statistically significant . apical seal is the single and most important factor in achieving success in surgical endodontics . a retrograde root filling is placed to establish an apical seal to prevent the passage of microorganisms or their products into periapical tissues . it is the first restorative material that consistently allows for the overgrowth of cementum and formation of bone , and also facilitates the regeneration of the periodontal ligament . it has certain drawbacks like difficulty in handling and a slow setting reaction , which might contribute to leakage , surface disintegration , loss of marginal adaptation and continuity of the material . , mta changes from ph 10.2 to ph 12.5 in 3 h. because of the interaction between mta and the organic phase of dentin , this results in a degradation of type 1 collagen , and the microhardness of dentin is altered . pmma bone cement has been widely used in orthopedic surgery , mainly for the fixation of prosthesis and also for stabilizing compressive vertebral fractures or filling bone defects . pmma bone cement has excellent adaptation to the cavity margins , in spite of the well - known polymerization shrinkage of acrylics . this is because the volume of cement increases to a maximum during polymerization before shrinking slightly , although not to its initial volume . the cement also tolerates a moist environment very well and is not affected by blood contamination . pmma bone cement does not seem to have any negative effects , even in large quantities needed during total hip arthroplasty . the lesser amount required would produce a much lower exothermic reaction and a much reduced amount of monomer . besides , heat dispersion is favored when the cement is in contact with a flowing liquid ( blood ) . scientists at the sree chitra tirunal institute for medical sciences and technology ( sctimst ) , thiruvananthapuram , had developed a novel formulation of cpc named  chitra - cpc ,  which has enhanced viscous and cohesive properties than conventional cpc . chitra - cpc could be mixed in varying consistencies , from mouldable putty to injectable paste . this flexibility provides immense advantage in clinical application as a bone and dentine substitute . besides this , it has a neutral ph during setting , is highly adaptable and adheres to the root canal surface . it is also dimensionally stable , easy to handle and has the property of osteotransductivity ( i.e. , active resorption at bony sites , facilitating bone remodeling ) . in the present study , pmma bone cement showed a mean microleakage of 0.24 mm , which was much less than mta ( 0.86 mm ) and chitra cpc ( 1.37 mm ) . the study showed that all materials exhibited microleakage , but there was significantly less microleakage in pmma bone cement when compared with chitra cpc and mta . the advantage of using ultrasonics for root end preparation is their smaller dimensions of the cavity prepared and improved access to the resected root - end cavity ( carr 1997 ) . lasers , if used properly with optimal settings for the target tissue , yield favorable results , including a decrease in dentine permeability ( aranha et al . , 2005 ) less crack formation on root canal walls ( wallace , 2006 ) , improved bactericidal activity ( gordon et al . , 2007 ) and effective removal of the smear layer and debris ( schoop et al . , 2007 ) . lasers have been shown to preserve the integrity of root end cavities better than ultrasonic devices from the standpoint of chipping . in the present study , the amount of dye penetration was found to be lesser in root ends prepared using er : yag laser when compared with ultrasonics . this may be due to better preservation of the integrity of root - end cavities from the standpoint of dentinal chipping . but , the difference was found to be not statistically significant ( p > 0.05 ) . confocal laser scanning microscopy is a simple method to test the adaptation of dental materials to the dentin . the advantages of clsm include 
 non - destructive examination of the samplesnon - dehydrated samples can be used : drying of samples , which is indispensable for conventional sem or tem , is not necessary with clsm , leading to a decreased risk , of shrinking or other drying artefactsno specific sectioning technique required : this decreases the possibility of artifacts produced during the preparation of the specimens by dehydration and sputter - coating procedure for sem evaluationrapid sampling is also available . non - destructive examination of the samples non - dehydrated samples can be used : drying of samples , which is indispensable for conventional sem or tem , is not necessary with clsm , leading to a decreased risk , of shrinking or other drying artefacts no specific sectioning technique required : this decreases the possibility of artifacts produced during the preparation of the specimens by dehydration and sputter - coating procedure for sem evaluation rapid sampling is also available . from the present study , the following conclusions were derived : 
 pmma bone cement is a better material as root end filling material to prevent microleakagemta still continues to be a gold standard root end filling material showing minimum microleakagethe amount of dye penetration was found to be lesser in root ends prepared using er : yag laser when compared with ultrasonics . pmma bone cement is a better material as root end filling material to prevent microleakage mta still continues to be a gold standard root end filling material showing minimum microleakage the amount of dye penetration was found to be lesser in root ends prepared using er : yag laser when compared with ultrasonics . further in vivo studies are needed to correlate with the finding of the present study .
background : surgical endodontic therapy comprises of exposure of the involved root apex , resection of the apical end of the root , preparation of a class i cavity , and insertion of a root end filling material . 
 mineral trioxide aggregate ( mta ) is now the gold standard among all root end filling materials . 
 mta is however difficult to handle , expensive and has a very slow setting reaction.aim:(1 ) to compare the sealing ability of mta , polymethylmethacrylate ( pmma ) bone cement and chitra calcium phosphate cement ( cpc ) when used as root end filling material using rhodamine b dye evaluated under a confocal laser scanning microscope . 
 ( 2 ) to compare the seal of root ends prepared using an ultrasonic retroprep tip and an er : yag laser using three different root end filling materials.statistical analysis : statistical analysis was performed using a one - way anova and a two - way anova , independent samples t - test and scheffe 's post hoc test using spss version 16 for windows.results:all the three materials , namely mta , pmma bone cement and chitra cpc , showed microleakage . comparison of microleakage showed maximum peak value of 0.86 mm for mta , 0.24 mm for pmma bone cement and 1.37 mm for chitra cpc . 
 the amount of dye penetration was found to be lesser in root ends prepared using er : yag laser when compared with ultrasonics , but the difference was found to be not statistically significant.conclusion:pmma bone cement is a better material as root end filling material to prevent apical microleakage . 
 mta still continues to be a gold standard root end filling material showing minimum microleakage . 
 er : yag laser is a better alternative to ultrasonics for root end preparations .