The effect of smear layer on microbial coronal leakage of gutta-percha root fillings. Bacterial penetration through canals of endodontically treated teeth in the presence or absence of the smear layer. Assessment of coronal leakage in teeth root filled with gutta-percha and a glass of ionomer root canal sealer. Coronal leakage following three obturation techniques. Sealability of the Trifecta technique in the presence or absence of a smear layer. A comparison of techniques for assessment of coronal dye leakage. The effect of two different root canal sealers and smear layer on resistance to root fracture. Bacterial retention in canal walls in vitro: effect of smear layer. The effect of smear layer on the push-out bond strength of root canal calcium silicate cements. Effect of passive ultrasonic irrigation and manual dynamic irrigation on smear layer removal from root canals in a closed apex in vitro model. Assessment of apical and coronal root canal seals using contemporary endodontic obturation and restorative materials and techniques. An in vitro comparison of adhesive systems to seal pulp chamber walls. Effect of removal of the smear layer on apical microleakage. Systematic reviews in endodontics--examples of GIGO? A comparative study of the removal of smear layer by three endodontic irrigants and two types of laser. Apical sealing ability of a new glass ionomer root canal sealer. Scanning electron microscope study on the efficacy of root canal wall debridement of hand versus Lightspeed instrumentation. The effect of German chamomile (Marticaria recutita L.) extract and tea tree (Melaleuca alternifolia L.) oil used as irrigants on removal of smear layer: a scanning electron microscopy study. The in vitro morphological effects of some current pre-treatments on dentin surface: a SEM evaluation. Leakage in vitro with IRM, high copper amalgam, and EBA cement as retrofilling materials. Adaptation and sealability of two contemporary obturation techniques in the absence of the dentinal smear layer. Effect of photo-activated disinfection on bond strength of three different root canal sealers Evaluation of smear layer removal after use of a canal brush: an SEM study.
The aim of this in vitro study was to determine the effect of removal of the smear layer on canal obturation as measured by penetration of bacteria from a coronal direction . One hundred and twenty extracted human teeth with straight , single root canals were decoronated . The canals were prepared using the modified double-flared technique with balanced force under copious irrigation . The apical matrix was prepared to size 40 and apical patency subsequently confirmed with a size 15 file . The teeth were divided r and omly into experimental groups ( 80 teeth ) and control groups ( 40 teeth ) . The root canals of 40 experimental and 20 control teeth were rinsed with 40 % citric acid and 2 % NaOCl to remove the smear layer before obturation . In experimental groups , 20 teeth with smear layer intact and 20 teeth with smear layer removed were obturated with lateral condensation of cold gutta-percha and Apexit sealer . A further 20 teeth with smear layer intact and 20 teeth with smear layer removed were obturated with the Trifecta technique with the same sealer . In control groups , 10 teeth with smear layer intact and 10 teeth with smear layer removed were obturated with lateral condensation of cold gutta-percha and Apexit sealer . These teeth were completely sealed both coronally and apically to serve as negative controls . The remaining 20 teeth with either smear layer intact or smear layer removed were not obturated and served as the positive controls . The root surface of each tooth was sealed with nail varnish . The cut end of a polypropylene tube was sealed around the coronal part of each root canal so that bacteria placed therein could move only through the obturated canal space . Each root was placed in a glass bottle containing sterile Todd-Hewitt Broth ( THB ) and aliquots of 0.5 ml of THB were injected into the polypropylene tube . The model system was centrifuged at 168 g. An innoculum of Streptococcus sanguis in THB was placed in each coronal chamber at 5-day intervals and daily observations were made for bacterial growth in the apical reservoir for 90 days . All positive control teeth showed bacterial penetration within 24 h , while the negative control teeth remained uncontaminated throughout the test period . Leakage through the experimental teeth was variable ranging from 7 to 86 days . There was no statistical significant difference ( P > 0.05 ) in leakage between the obturated canal when the smear layer was either removed or intact OBJECTIVES The goal of this study is to determine if the smear layer affects the passage of bacteria through or around obturating material as evidence d by penetration of bacteria through and out the canal . Specifically , this study focused on determining the effect of the smear layer on the magnitude of bacterial penetration through the apical foramen . METHODS Thirty extracted , maxillary central or lateral incisors were collected . Teeth were r and omly assigned ( 10 teeth per group ) to three groups : ( 1 ) smear layer removed , ( 2 ) smear layer present , and ( 3 ) negative control . Canal preparation and obturation using lateral condensation , gutta percha , and AH 26 sealer was performed on all of the teeth . Removal of the smear layer was accomplished by rinsing with 17 % EDTA . The model systems consisted of an upper chamber attached to the cemento-enamel junction and a lower chamber at the apices of the teeth . St and ardized bacterial suspensions containing Fusobacterium nucleatum , Campylobacter rectus , and Peptostreptococcus micros were inoculated into the upper chambers . Models were incubated anaerobically at 37 degrees C. At various times over a 60-day period , sample s were taken from the lower chamber and spiral-plated on selective-differential media to determine numbers and types of bacteria . RESULTS Leakage results were as follows : ( 1 ) smear layer present-6/10 leaked ; ( 2 ) smear layer removed-0/10 leaked ; ( 3 ) negative control-0/10 leaked . Profiles of bacterial leakage were similar among the groups . F. nucleatum was the predominant microorganism . CONCLUSIONS This study indicated that removal of the smear layer reduced the leakage of bacteria through the root canal system The effect on coronal leakage of the use of either a single gutta-percha cone or cold lateral condensation of gutta-percha , with a glass ionomer sealer cement was studied . In addition , the effect of the removal of the smear layer was also determined . Eighty-eight single-rooted teeth were prepared chemomechanically using h and files , with the balanced force technique . Lubrication was provided by either Hibiscrub ( maintaining the smear layer ) or an EDTA-containing paste ( to remove the smear layer ) . Copious irrigation was carried out with 2.2 % sodium hypochlorite . The teeth were allocated r and omly to four groups of 20 teeth each , the remaining eight teeth served as controls . Two groups of teeth , one with and one without smear layer , were obturated with either a single gutta-percha cone or cold laterally condensed gutta-percha , with Ketac Endo as the sealer . The teeth were stored for 6 weeks , thermocycled , and the extent of coronal leakage determined for each group after immersion in India ink for 90 h. The teeth were demineralized , dehydrated and immersed in methyl salicylate , which rendered them transparent . Linear measurement of maximum dye penetration was recorded . The mean depth ( + SD ) of leakage for the groups in which the smear layer was left intact was 1.68 mm ( + 0.38 ) for the single cone ( A1 ) and 2.29 mm ( + 1.58 ) for lateral condensation ( B1 ) . When the smear layer was removed the mean depth of leakage for the single cone group ( A2 ) was 2.04 mm ( + 0.73 ) and 2.37 mm ( + 1.70 ) for the laterally condensed group ( B2 ) . There was no significant difference in coronal leakage between the groups ( P > 0.05 ) AIM To compare coronal bacterial and India ink leakage in three different obturation techniques with the smear layer having been removed . METHODOLOGY Seventy extracted single-rooted teeth were instrumented to an apical preparation size 7 Profile Series 29 ( Tulsa Dental Products , Tulsa , OK , USA ) . The smear layer was removed and 20 teeth were r and omly obturated with lateral compaction , 20 teeth with vertical compaction , and 20 teeth with Thermafil ( Tulsa Dental Products , Tulsa OK , USA ) . Ten teeth were used for positive ( five teeth ) and negative ( five teeth ) controls . Teeth were stored for 90 days in 100 % humidity , then subjected coronally to Proteus vulgaris for 21 days to assess bacterial leakage . Following bacterial challenge , India ink was placed coronally for a further 21 days , then scored according to depth of dye leakage . RESULTS  Vertical compaction leaked significantly less than lateral compaction during bacterial challenge . However , when dye was used there were no significant differences . CONCLUSIONS Bacterial leakage and dye leakage demonstrated considerable variability . The use of a dye following bacterial testing may highlight the failure of experimental devices and vertical root fractures , thus avoiding false positive results found with bacterial testing alone The aim of this in vitro study was to assess the sealability of a recently introduced thermoplasticized gutta-percha technique ( Trifecta , Hygenic Corp. , OH , USA ) in the presence or absence of a smear layer . A total of 100 teeth with single straight root canals were included in the study . The teeth were decoronated and the canals prepared with a modified double-flared technique under constant irrigation with 2.5 % sodium hypochlorite solution . The apical matrix was prepared to size 40 and apical patency subsequently confirmed with a size 10 file . Four teeth were discarded for technical reasons and the remaining 96 allocated r and omly into two groups of 44 teeth and a group of eight teeth which acted as controls . Canals in group 1 were obturated r and omly with either cold lateral condensation of gutta-percha or with the Trifecta technique . Canals in Group 2 were rinsed with 17 % REDTA to remove the smear layer and then obturated with lateral condensation or the Trifecta technique . All teeth were suspended in India ink for 9 days , demineralized , and rendered transparent prior to the assessment of apical linear dye penetration . Apical extrusion of sealer and gutta-percha occurred commonly but there was no significant difference between the four obturation groups . However , overall , there was significantly more extrusion of sealer with the Trifecta technique compared with lateral condensation ( P < 0.05 ) . The majority of canals ( 79 out of 88 ) had no evidence of apical leakage and there was no significant difference between the groups . ( ABSTRACT TRUNCATED AT 250 WORDS This study was design ed to compare different techniques for coronal dye leakage testing . One hundred and fifty extracted human anterior teeth were fully instrumented and r and omly divided into two experimental groups of 60 teeth each , plus two groups of 15 teeth each for positive and negative controls . One group was rinsed with 5.25 % NaOCl ( smear layer intact ) , whereas the other group was flushed with 17 % EDTA and 5.25 % NaOCl ( smear layer removed ) . Roots were obturated with gutta-percha using lateral condensation and AH Plus as root canal sealer . Each experimental group was divided into three subgroups of 20 teeth each for three methods of testing coronal dye leakage : passive dye penetration , penetration with vacuum applied , and fluid filtration methods . The teeth were left in 100 % humidity at 37 degrees C for 5 days before being immersed in Indian ink for 2 days and cleared . The linear extent of dye penetration was measured . Mean depth of leakage for the groups with the smear layer intact was 2.5 + /- 1.0 mm for passive dye penetration , 6.7 + /- 2.8 mm for vacuum dye penetration , and 3.0 + /- 1.1 mm for fluid filtration dye penetration . In the group in which the smear layer was removed , the mean depths of leakage were : 3.2 + /- 2.1 mm for passive dye penetration , 5.8 + /- 2.8 mm for vacuum dye penetration , and 3.4 + /- 2.1 mm for fluid filtration . The vacuum method result ed in significantly ( p < 0.05 ) more dye penetration than fluid filtration and passive dye penetration . The presence or absence of smear layer had no statistically significant effect ( p > 0.05 ) on any of the leakage testing techniques The purpose of this in vitro study was to test the effect of Ketac-Endo ( KE ) and AH 26 on resistance to root fracture and also to evaluate the effect of smear layer .  Seventy-two human maxillary canine teeth were r and omly divided into six groups ( n = 12 ) and were prepared using six different methods : group 1 : KE , without smear layer ( smear - ) ; group 2 : KE , with smear layer ( smear + ) ; group 3 : AH 26 , smear ( - ) ; group 4 : AH 26 , smear ( + ) ; group 5 ( negative control ) : nonprepared ; group 6 ( positive control ) : prepared but unfilled . After storing 1 week in 100 % humidity at 37 degrees C , the coronal lingual walls and root canal spaces were lowered 2 mm below the buccal walls of the roots . The sample s were placed into acrylic resin blocks so that 10 mm of buccal roots were exposed and were placed in a specially design ed steel pad at an angle of 15 degrees to the long axis of the root . A slowly increasing force was applied at the junction of the buccal wall and root canal space until fracture occurred . The force required to fracture each tooth was recorded as kg and statistically analyzed using one-way analysis of variance and Duncan tests . The results indicated that instrumentation of the root canals significantly weakened the tooth structure to fracture ( p < 0.05 ) . The canals obturated with either sealer were significantly stronger than roots whose canals were instrumented but not obturated ( p < 0.05 ) , and there was no difference between the sealers . The presence or absence of the smear layer did not cause any significant effect on the root fracture resistance of the teeth ( p > 0.05 ) When dentin is planed by endodontic instruments , a smear layer forms . Whether this layer should be removed is unknown and controversial . This study was conducted to assess the effect of the smear layer on retention of bacteria using an in vitro root canal bacterial colonization model . Canals of 26 extracted human canines were step-back prepared using 2.5 % NaOCl . Teeth were then r and omly divided into two groups based on the type of high volume final flush : 1 - 20 ml of sterile saline ( 0.85 % wt/vol ) or ( 2 - 10 ml of 17 % EDTA followed by 10 ml of 2.5 % NaOCl which removes smear layer . Streptococcus anginosus ( milleri ) was cultured in trypticase soy broth supplemented with 0.5 % yeast extract at 37 degrees C in 5 % CO2 . Cells were harvested by centrifugation and resuspended in fresh media . Serial dilutions were performed to achieve inocula of 10(6 ) colony-forming units in a 30-microliters volume . Teeth were inoculated and incubated for 2 h in 5 % CO2 at 37 degrees C. Following incubation , teeth were split and processed for microbiological analysis . Numbers of colonizing bacteria were determined by a spiral-plating system . Enumeration of the numbers of bacteria revealed a reproducible , order of magnitude difference ( p = 0.0002 ) between teeth with smear layer ( 10(4 ) colony-forming units ) versus teeth without smear layer ( 10(5 ) colony-forming units ) . This suggests that smear layer produced during root canal therapy may inhibit bacterial colonization of root canals . One suggested mechanism is that smear layer may block bacterial entry into dentinal tubules INTRODUCTION The aim of this study was to evaluate the effect of smear layer removal on the push-out bond strength between radicular dentin and three calcium silicate cements ( CSC ) in comparison with gutta percha and sealer . METHODS Eighty human anterior extracted teeth were decoronated , cleaned and shaped to size 50/0.05 apically and r and omly divided into 2 major groups : ( A ) smear layer preserved , and ( B ) smear layer removed using irrigation with 17 % EDTA . Roots within each major group were further divided into 4 subgroups according to the obturation material used : ( 1 ) ProRoot MTA , ( 2 ) Biodentine , ( 3 ) Harvard MTA , ( 4 ) Gutta percha and AH-plus sealer . Obturated roots were stored in synthetic tissue fluid for 7 days to allow maximum setting of the root filling material s. Three 2-mm-thick slices were obtained from each root at different section levels ( coronal , middle , apical ) . The canal diameters and slice thickness were measured , and the adhesion surface area for each slice was calculated . Push-out bond strength test was carried out using a universal testing machine . The bond failure mode was assessed under an optical microscope at 40 × . RESULTS The mean push-out bond strength in groups 1A , 2A and 3A were 7.54 ( ±1.11 ) , 7.64 ( ±1.08 ) and 8.79 (±1.55)MPa respectively , while those for groups 1B , 2B and 3B were 6.58 ( ±1.13 ) , 6.47 ( ±1.08 ) , 7.71 (±1.81)MPa , respectively . In the gutta percha and sealer groups the push-out bond strength means were : 1.98 ( ±0.48 ) and 2.09 (±0.51)MPa in the preserved and removed smear layer groups respectively . The push-out strength values were significantly reduced when the smear layer was removed in the CSC groups ( P<0.05 ) while no significant difference was detected in the gutta percha and sealer groups . CONCLUSIONS Based on the conditions of this ex vivo study , it can be concluded that smear layer removal is detrimental to the bond strength between calcium silicate cements and dentin AIM To compare the effect of passive ultrasonic irrigation with manual dynamic irrigation on smear layer removal from root canals using a closed apex in vitro model . METHODS The root canals of 45 freshly-extracted human single-rooted m and ibular premolar teeth were prepared by the Pro-Taper rotary system to an apical preparation of F4 size . Prepared teeth were r and omly divided into three groups ; two experimental groups and one control group ( n = 15 ) on the basis of the type of activation of final irrigation as follows : ( a ) Group A , 3 % sodium hypochlorite ( NaOCl ) and 17 % ethylenediaminetetraacetic acid ( EDTA ) , no activation received ; ( b ) Group B , 3 % NaOCl and 17 % EDTA , ultrasonic activation with a small file ; and ( c ) Group C , 3 % NaOCl and 17 % EDTA , manual activation with a master gutta-percha point . The prepared teeth were decoronated and split into two halves longitudinally , and observed under a scanning electron microscope to assess the removal of the smear layer . RESULTS In the apical-third region , the mean smear scores for groups B and C were significantly less than those of Group A ( control group ) ( P < 0.05 ) . CONCLUSION Both activation techniques are important adjuncts in removing the smear layer , with manual dynamic activation being a simpler , safer , and more cost-effective technique AIM The purpose of this study was to evaluate the sealing ability of two contemporary  endodontic obturation and restorative techniques and material s. METHODOLOGY Seventy-nine extracted human single-rooted teeth were distributed r and omly in two experimental groups of 36 and 37 specimens ( groups 1 and 2 , respectively ) , one group of three positive controls and one of three negative controls . The teeth were radiographed preoperatively , accessed , and instrumented . After smear layer removal , the teeth in group 1 were obturated using the System B and Obtura and were restored coronally with Core Paste using Tenure as a bonding agent . The teeth in group 2 were obturated using the Microseal technique and were restored coronally with amalgam using Panavia 21 as a bonding agent . All teeth in groups 1 and 2 were coated with three layers of nail varnish on all of their surfaces apart from the apical 4.0 mm and the coronal area above the cemento-enamel junction . The positive control teeth were obturated , restored coronally and completely coated with varnish , whereas the negative control teeth were not obturated , restored coronally , nor coated with varnish . The teeth were radiographed postoperatively and retained in saline solution for 10 days . For the next 10 days they were submerged in India ink . Subsequently all teeth were demineralized , dehydrated and rendered transparent . Dye penetration was measured using a stereomicroscope . RESULTS All material s and techniques provided minimal to zero dye penetration , apart from one specimen in the Core Paste group that showed 4.0 mm of dye penetration . The Wilcoxon rank sum test and t-test showed no statistically significant differences and all material s and techniques tested presented with a high degree of acceptability . CONCLUSIONS It was concluded that these contemporary techniques and material s provide equally good results , but long-term studies are needed for outright inferences to be drawn relative to their clinical performance AIM To compare in vitro the sealing properties of five different dentine adhesive material s ( Prime&Bond NT ( PBNT ) ; Prompt L-Pop ( PLP ) ; Clearfil SE Bond ( CSEB ) ; Scotchbond Multi Purpose Plus ( SMPP ) ; EBS-Multi ( EBSM ) ) inside the pulp chamber . METHODOLOGY Seventy-five recently extracted human molar teeth were used . The roof of the pulp chambers and roots were removed under water cooling . Pulp tissue was removed , and the canal orifices were sealed . The pulp chambers were then treated with 5 % sodium hypochlorite ( NaOCl ) for 1 min . The teeth were r and omly divided into five groups of 15 teeth each . Adhesive systems were applied to the pulp chamber walls according to the manufacturers ' instructions . The sample s were connected to Plexiglass plates , and a fluid filtration method was used for quantitative evaluation of leakage . Measurements of fluid movement were made at 2-min intervals for 8 min . The quality of seal of each specimen was measured immediately , after 24 h , 1 week and 1 month . The data were statistically analysed by repeated- measurements multivariate anova , Friedman test , Wilcoxon signed rank test , Kruskal-Wallis of one-way anova and Mann-Whitney U-tests . The pulp chamber wall with and without NaOCl and resin-dentine interfaces of specimens were observed under a scanning electron microscope ( SEM ) . RESULTS The leakage values of the material s were significantly different at different measurement periods . In all groups , leakage values decreased with time ( P < 0.05 ) . PBNT and PLP had the least leakage during immediate measurements ( P < 0.05 ) . After 1 month , leakage of all adhesive systems was not significantly different ( P < 0.05 ) . SEM observation of pulp chamber walls demonstrated that the irregular dentine surface without smear layer was present in the nontreated group . However , NaOCl application removed the collagen fibrils leaving the dentine surface smooth . At resin-dentine interfaces of specimens , no hybridization zone was observed . CONCLUSIONS None of the material s had created a perfect seal to the pulp chamber walls . PBNT and PLP had better sealing over the short term , but over the long term , there were no differences between the material It has been shown previously that the smear layer created during instrumentation of the root canal promotes apical microleakage . The purpose of the present study was to investigate the effect of removal of the smear layer on apical microleakage , using the fluid filtration method . Thirty-six single-rooted human premolar teeth were used . Six of the teeth were selected r and omly as controls , and the remaining 30 teeth were r and omly divided into two groups of 15 teeth each . For the first group ( group 1 ) teeth were irrigated with NaOCl only ( smear layer not removed ) . In the second group ( group 2 ) the teeth were irrigated with 15 % EDTA , followed by NaOCl to remove the smear layer . Both groups were filled with thermoplasticized gutta-percha ( Obtura II ) using glass-ionomer cement as sealer . All teeth were stored at 37 degrees C and 100 % humidity for 2 days . Apical microleakage of the filled root canal was measured by the fluid filtration technique . Hydraulic conductance was measured by the movement of an air bubble in a capillary tube after a pressure of 200 mm Hg was applied to the system . The mean microleakage rate of group 1 and group 2 were 13.0 ( SD + /- 5.1 ) and 16.9 ( SD + /- 15.3 ) nl/s , respectively . Removal of the smear layer caused significantly more apical microleakage ( p < 0.05 , Student 's t test ) than when the smear layer was left intact In many areas of medicine the amount of published information is increasing at an exponential rate , making it difficult for the clinician to condense the data to a manageable amount of valuable and useful information . Systematic review s have been suggested as a remedy for this information overload . Such review s are regarded as the highest level of evidence . Certain statistical methods , e.g. , meta- analysis , have also been introduced for the calculation of a more comprehensive summation of the compiled results from studies with small sample sizes . These findings would then serve as an authoritarian guide for evidence -based practice . Endodontists have lately jumped on the b and wagon of systematic review s and meta-analyses , and papers on various topics are being published . Well done , such comprehensive information would be very useful and authoritative for the practitioner . Alarmingly , the quality of these recent publications is negatively correlated to the frequency . This can have serious consequences in the clinical arena if spurious information is given a seal of approval when communicated as facts in refereed journals . A systematic literature review is design ed to focus on a single question and to synthesize all high- quality research reports relevant to the question . In these studies , however , sources of bias are often not controlled . Therefore , even the best review and meta- analysis becomes useless if it is based on poorly design ed research . Furthermore , these review s are mostly based on published data which are too often biased toward studies that show significant differences in results and /or outcome . “ Uninteresting ” conclusions tend not to be published . Endodontic literature , thus far , is short on well design ed and executed r and omized clinical trials . Furthermore , clinical protocol s often have many important “ proprietary ” modifications that make comparison difficult . This makes it very hard to undertake a systematic review to answer a narrow question . Such GIGO ( garbage in , garbage out ) can easily lead to biased conclusions and reinforce already existing biased comclusions . An example of such bias can be illustrated by a meta- analysis recently published . The study focused on assessing if there were differences in outcome between 1 and 2 treatment visits when treating teeth with apical periodontitis . Relevant publications on this topic are rare , and with the narrow inclusion criteria only 3 investigations were available for the review . However , the only factors connecting these 3 studies was the words “ single ” and “ two visits ” in the title . Beyond that , the selected studies are too different and inadequate for the study . Only 1 study is somewhat demonstrably r and omized , and outcome assessment s are based on 3 vastly different criteria . Two of the studies use calcium hydroxide as intracanal dressing , whereas the third uses no intervisit medication . Complexity of initial pathology and healing time are also clearly factors of great importance but not controlled . In addition , sample sizes in the component studies as well as the final cohort are all too small for the conclusions that there was no significant difference between 1or 2-visit treatment protocol s. To undertake and publish a meta- analysis on such an incomplete sample is counterproductive . Although the publication noted its numerous limitations , it will still communicate erroneous conclusions with a poor scientific foundation to the less informed reader . There are other examples of recently published systematic review s that are very ambiguous and tend to communicate spurious facts . One of these studies looks at the effect of smear-layer removal on sealing ability of root canal obturation . The study is entirely limited to laboratory experiments , with the majority of evaluations using dye leakage which is generally considered to be unreliable . This is an example of review ers lacking content expertise . The authors draw the conclusion , using defective review material , that removal of smear layer enhances the seal of the root filling . We may generally believe that this is the truth AIM The effects of three endodontic irrigants and two types of laser on a smear layer created by h and instrumentation were evaluated in vitro in the middle and apical thirds of root canals . METHODOLOGY Sixty human mature extracted m and ibular premolar teeth with a single root canal and a closed apex were distributed r and omly into five groups of 12 teeth each . Whilst cleaning and shaping up to a size 60 master apical file with a step-back technique , the root canals were irrigated with 3 mL of 5.25 % NaOCL and 3 % H2O2 , alternately , between each file size . Group 1 ( G1 ) were control specimens that were irrigated with a final flush of 17 % EDTA . The teeth in group 2 ( G2 ) were irrigated with a final flush of 6 % phosphoric acid , and group 3 ( G3 ) with 6 % citric acid . In the specimens of group 4 ( G4 ) the root canals were irradiated with a carbon dioxide ( CO2 ) laser , and specimens of group 5 ( G5 ) were irradiated using an Er : YAG laser . The teeth were split longitudinally and prepared for examination by scanning electron microscopy . RESULTS Control specimens ( G1 ) showed clean root-canal walls with open dentinal tubules in the middle one-third , but in some specimens thick smear layer was observed in the apical one-third . Specimens irrigated with a final flush of 6 % phosphoric acid ( G2 ) or 6 % citric acid ( G3 ) were cleaner than with 17 % EDTA , showing very clean root canal surfaces in the middle one-third but in the apical one-third the smear layer was not completely removed , especially at the openings of the dentinal tubules . The specimens irradiated with the CO2 laser ( G4 ) showed clean root-canal walls with the smear layer absent , charred , melted , recrystallized and glazed in both middle and apical thirds . The root-canal walls of the specimens irradiated with the Er : YAG laser ( G5 ) revealed an absent smear layer with open dentinal tubules in the middle and apical thirds . Statistical analysis showed no significant difference in the cleanliness of root-canal wall between G1 and G2 , and G1 and G3 . However , there were statistically significant differences ( P < 0.01 ) between G1 and G4 , and G1 and G5 in the cleanliness of the middle and apical one-thirds of the root canals . CONCLUSIONS Irrigation with 17 % EDTA , 6 % phosphoric acid and 6 % citric acid did not remove all the smear layer from the root-canal system . In addition , these acidic solutions demineralized the interbular dentine around tabular openings , which became enlarged . The CO2 laser was useful in removing and melting the smear layer on the instrumented root-canal walls and the Er : YAG laser was the most effective in removing the smear layer from the root-canal wall This study compared the sealing ability of Ketac Endo with and without smear layer and Tubli Seal .  Thirty upper central incisors and canines with straight canals were instrumented and r and omly divided into three equal groups of 10 . All teeth were obturated with laterally condensed gutta-percha . An additional group of five teeth with unobturated++ root canals served as positive controls . The sealers were Tubli Seal ( group A ) , Ketac Endo ( group B ) , and Ketac Endo preceded by the removal of the smear layer ( group C ) . The teeth were immersed in India ink for 7 days , centrifuged for 5 min at 3000 rpm , cleared , and then examined under a light microscope at X 50 magnification . The mean value of ink penetration for group A was 0.14 mm , for group B 0.24 mm , and for group C 0.48 mm . No statistically significant differences were observed among groups ( p > 0.05 ) AIM The aim of this in vitro study was to compare the efficacy of root canal wall debridement following h and versus LightSpeed instrumentation . METHODOLOGY Twenty recently extracted single-rooted teeth were paired and r and omly placed into two treatment groups of 10 teeth each . In group 1 , a step-back instrumentation without initial coronal flaring with stainless steel Hedstroem files was used ; group 2 was instrumented with Ni-Ti LightSpeed instruments . Both groups had the same irrigation regimen : 2.5 % NaOCl and a 15 % EDTA solution . The teeth were then decoronated and each root split longitudinally into two halves to be examined using the scanning electron microscope ( SEM ) . The presence of superficial debris and smear layer was evaluated by a st and ardized grading system , and the result ing scores su bmi tted to nonparametric statistics . RESULTS Under the conditions of this study , the removal of superficial debris was generally excellent with both canal preparation techniques . Both techniques result ed in variable presence of residual smear layer , with a canal wall covered by smear layer as the predominant characteristic . Generally , the amount of smear layer was greater in the apical than in the middle third of the root , however , this difference was statistically significant ( P < 0.005 ) only in h and -instrumented teeth . The use of LightSpeed instruments was associated with significantly more ( P < 0.05 ) smear layer presence in the middle region of the root when compared with h and instrumentation . In addition , less smear layer was present in the apical region following LightSpeed instrumentation than stainless steel h and files , but this difference was not statistically significant . Differences in debridement between the two halves of the same root were more evident with LightSpeed than manual instrumentation , however , there was no statistical significance . CONCLUSIONS It may be inferred that the choice between h and and LightSpeed instrumentation should be based on factors other than the amount of root canal debridement , which does not vary significantly according to the instruments used AIM To compare the cleaning effectiveness of chamomile hydroalcoholic extract and tea tree oil to 2.5 % sodium hypochlorite ( NaOCl ) solution as an intracanal irrigant for the removal of the smear layer . METHODOLOGY Forty extracted , single-rooted , mature , permanent , human teeth were allocated at r and om into one of three experimental groups of ten teeth and two control groups of five teeth . For each tooth , the pulp chamber was accessed and the canal prepared using K-type files and Gates-Glidden burs , using a step-back technique ; the apical stop was prepared to a size 30 . Each canal was subsequently irrigated with one of the following solutions : distilled water ( as a negative control ) , 2.5 % NaOCl + 17 % ethylenediamine tetraacetic acid ( EDTA ) ( as a positive control ) , chamomile or tea tree oil or 2.5 % NaOCl . Each tooth was split longitudinally and prepared for examination by scanning electron microscopy ( SEM ) . The quantity of smear layer remaining on the three levels of each canal ( coronal , middle and apical ) was examined using magnifications of 2000 and 5000x . The data were analysed using nonparametric Kruskal-Wallis and Mann-Whitney U-tests . RESULTS The most effective removal of smear layer occurred with the use of NaOCl with a final rinse of 17 % EDTA ( negative control ) followed by the use of a chamomile extract . Chamomile extract was found to be significantly more effective than distilled water and tea tree oil ( P < 0.008 ) . The use of a 2.5 % NaOCl solution alone , without EDTA and that of tea tree oil , was found to have only minor effects . There was no statistical difference between distilled water , 2.5 % NaOCl and tea tree oil . CONCLUSIONS The efficacy of chamomile to remove smear layer was superior to NaOCl alone but less than NaOCl combined with EDTA This in vitro study morphologically evaluated the effect of some current surface pre-treatments on dentin , using scanning electron microscopy , and related these morphological alterations to clinical implication s. The labial surfaces of 30 bovine lower incisors were ground to obtain a flat dentin surface and were finished with 600-grit SiC paper to produce st and ardized smear layers . The teeth were r and omly divided into six groups of five each . Group 1 was the control group , smear layer covered dentin ; Group 2 was etched with 37 % phosphoric acid ( PA ) for 15 seconds ; Group 3 , 37 % PA for 15 seconds , followed by 10 % NaOCl for 60 seconds ; Group 4 , 10 % NaOCl for 60 seconds ; Group 5 , a self-etching primer ( Clearfil SE Bond , CSEB-primer ) was applied for 20 seconds ; Group 6 , CSEB-primer for 20 seconds , followed by NaOCl for 60 seconds . The specimens were fixed , dehydrated , dried and analyzed by SEM . Treatment with 37 % PA removed the smear layer , funneled the tubules and result ed in a collagen-rich surface which appeared to have collapsed in its outermost part , producing a dense surface layer covered with silica particles . When 37 % PA treatment was followed by 10 % NaOCl , the collagen network was removed to reveal an eroded , rough mineral surface with numerous lateral branches and larger than normal tubular orifices . The action of 10 % NaOCl on the smear layer-covered dentin showed no significant alteration in surface morphology . The treatment with CSEB-primer dissolved the smear layer but only partially dissolved the smear plugs . The tubules did not present the typical funnel shape seen following PA treatment . These morphological aspects on dentin surface must influence bonding results . The dentin surface alterations produced by PA appeared to be a very severe demineralization pattern , quite irregular and less permeable to monomer infiltration , while the surface provided by the self-etching primer appeared to be a more uniform , less porous surface , and the association with simultaneous monomer infiltration may reduce the occurrence of mistakes in clinical bonding procedures An in vitro dye leakage study was performed to compare the sealing ability of  high copper amalgam with Copalite , IRM , and EBA cement when used as retrofilling material s. Fifty-one extracted anterior teeth were instrumented and then obturated with gutta-percha . The apical 3 mm of the roots were resected and 2-mm deep apical preparations were made . The roots were then r and omly placed into three groups and retrofilled with one of the experimental material s. After 72 h in India ink , the teeth were cleared and evaluated for leakage with a stereomicroscope . No leakage was evident in the three teeth used as negative controls and complete leakage was noted in the three positive control teeth . Statistical analysis showed that IRM and EBA cement had significantly less leakage than amalgam with Copalite . The difference between the EBA cement and IRM was not significant AIM The aim of this study was to evaluate the adaptation and short- and long-term sealability of two different thermoplastic techniques -- a core carrier technique , Thermafil ; and a warm vertical continuous wave of compaction technique , System B. METHODOLOGY Fifty-one mesial roots of m and ibular molars with separate canals , patent canal orifices and curvature greater than 15 degrees were cleaned and shaped with Orifice Shapers and ProFile.04/.06 taper Ni-Ti rotary files using 5.25 % NaOCl and 17 % REDTA to a size 30.04 taper Profile at the apex to create a continuous tapered preparation . Canals were r and omly obturated with Sealapex root canal sealer and either alpha-phase gutta-percha on a plastic Thermafil carrier , or nonst and ardized beta-phase gutta-percha using the System B heat source . Proximal radiographs of roots were evaluated by three examiners based on established criteria for overall material adaptation , apical adaptation and filling material extrusion . Teeth were r and omly separated into three groups of 17 each and placed in black India ink for 10 days , 24 h , or after 67 days storage in Hank 's Balanced Salt Solution . All roots were demineralized and rendered transparent . Three examiners evaluated the apical leakage by the linear measurement of dye penetration under the stereo-microscope . The movement of filling material into canal irregularities was also evaluated . RESULTS Both obturation techniques were not significantly different in the overall canal obturation and in the apical third adaptation ( P > 0.05 ) . Significantly more filling material extrusion beyond the apex was noted with the Thermafil technique ( P < 0.001 ) . No significant difference was found amongst the 67-day , 10-day and 24 h System B groups ( P > 0.05 ) . The 67-day Thermafil group showed significantly more leakage than the 10-day and 24 h Thermafil groups . There was a significant difference in the degree of leakage between the 67-day Thermafil group and the 67-day System B group ( P < 0.05 ) , but not between the 10-day and 24 h groups ( P > 0.05 ) . Both obturation techniques produced substantial filling material movement into canal irregularities . CONCLUSIONS It was concluded that Thermafil demonstrated more filling material extrusion beyond the apex and significantly more long-term apical leakage Introduction : The aim of this in vitro study was to evaluate the bond strength of Photo-Activated Disinfection ( PAD ) system to dentin with different root canal sealers by using a push-out test design . Material s and Methods : A total of 30 extracted m and ibular premolar teeth with single and straight roots were used . The crowns were removed and the root canals were prepared by using ProTaper rotary files . The smear layer was removed and the roots were r and omly divided into two groups ( n = 15 ) according to the use of PAD system as the final disinfecting agent . Each group was then divided into 6 ( n = 5 ) subgroups and obturated with gutta-percha and 3 different root canal sealers . The groups were Group 1 : Sodium hypochlorite ( NaOCl ) + ethylenediaminetetraacetic acid (EDTA)-AH Plus sealer ; Group 2 : NaOCl + EDTA + PAD-AH Plus ; Group 3 : NaOCl + EDTA-Sealapex ; Group 4 : NaOCl + EDTA + PAD-Sealapex ; Group 5 : NaOCl + EDTA-mineral trioxide aggregate (MTA)-Fiallapex ; and Group 6 : NaOCl + EDTA + PAD-MTA-Fillapex . 1-mm thickness horizontal sections ( n : 5 × 4 = 20 ) were sliced for the push-out bond strength measurement . Results : Group 3 and 4 showed significantly lower bond strengths compared with all the other groups ( P < 0.05 ) . No statistically significant difference was found among Groups 1 , 2 and 5 , but there was statistically significant difference between Group 5 and 6 ( P < 0.05 ) . Conclusion : This in vitro study indicated that the PAD system adversely affected the bond strength of the MTA Fillapex root canal sealer OBJECTIVE The objective of this study was to evaluate smear layer removal after using the new CanalBrush ( Coltene/Whaledent GmbH+Co . KG , Germany ) . STUDY DESIGN Twenty extracted maxillary anterior teeth were r and omly divided into 2 equal groups . The canals of the teeth in each group were instrumented with ProTaper Universal rotary files ( Dentsply Maillefer , Switzerl and ) . Following each file use , the root canals in both groups were irrigated with 5.25 % NaOCl and 15 % EDTA . At the end of instrumentation , the canals in group 2 were flushed with 15 % EDTA , then a CanalBrush was used for 30 seconds , and a final irrigation was conducted with 5.25 % NaOCl . All teeth were processed for scanning electron microscopy ( SEM ) , and the removal of the smear layer was examined in the apical , middle , and coronal thirds . Analyses of SEM images were performed by 2 independent evaluators in a blinded manner and using a 4-point scoring system . RESULTS The middle and apical thirds of the root canals in group 2 showed lower average scores than those in group 1 , but the difference was not statistically significant . There was no significant difference in the coronal score between the groups ( P > .05 ) . CONCLUSIONS Irrigating with brushing tended to produce cleaner canal walls , but irrigating brushing was not significantly better than irrigation alone in removing the smear layer on the canal walls
Under the conditions of these in vitro leakage studies , it is concluded that smear layer removal improves the fluid-tight seal of the root canal system whereas other factors such as the obturation technique or the sealer , did not produce significant effects
The purpose of this systematic review was to determine whether smear layer removal reduces leakage of obturated human teeth in vitro .