Bacterial penetration through canals of endodontically treated teeth in the presence or absence of the smear layer. The effect of smear layer on microbial coronal leakage of gutta-percha root fillings. A Scanning electron microscopic evaluation of intracanal smear layer removal by two different final irrigation activation systems Smear layer removal with passive ultrasonic irrigation and the NaviTip FX: a scanning electron microscopic study. Effect of removal of the smear layer on apical microleakage. Bacterial retention in canal walls in vitro: effect of smear layer. Coronal leakage following three obturation techniques. Assessment of apical and coronal root canal seals using contemporary endodontic obturation and restorative materials and techniques. Evaluation of smear layer removal after use of a canal brush: an SEM study. Evaluation of the Effects of Enameloplasty and Air Abrasion on Sealant Micro-Leakage Effect of passive ultrasonic irrigation and manual dynamic irrigation on smear layer removal from root canals in a closed apex in vitro model. Sealability of the Trifecta technique in the presence or absence of a smear layer. Assessment of coronal leakage in teeth root filled with gutta-percha and a glass of ionomer root canal sealer. The effect of smear layer removal on marginal contraction gaps. A clinical and histological evaluation of conservative pulpal therapy in human teeth. Bacterial reduction with nickel-titanium rotary instrumentation. Preservation of alveolar bone in extraction sockets using bioabsorbable membranes.
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 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 Aim : The aim of this study was to compare smear layer removal at apical 1 mm level after final irrigation activation with an EndoVac system and Max-I probe . Material s and Methods : Fifty freshly extracted maxillary central incisors were r and omly divided into two groups after completing cleaning and shaping with ProTaper rotary files . In one group , final irrigation was performed with an EndoVac system while in the other group final irrigation was performed with a 30 gauge Max-I probe . 3 % sodium hypochlorite and 17 % ethylenediaminetetracetic acid were used as final irrigants in all teeth . After instrumentation and irrigation , the teeth were sectioned longitudinally into buccal and palatal halves and viewed under a scanning electron microscope for evaluation of the smear layer . Statistical analysis was performed using the Kruskal Wallis and Mann-Whitney U tests . Results : The EndoVac group showed significantly better smear layer removal compared with the Max-I probe at the apical 1 mm level . Conclusion : An apical negative pressure system ( EndoVac ) results in better debridement at apical 1 mm when compared with side-vented closed ended needle irrigation ( Max-I probe ) OBJECTIVE The aim of this study was to compare the effect of continuous , intermittent passive ultrasonic irrigation ( PUI ) and active scrubbing of irrigants with NaviTip FX ( Ultradent , South Jordan , UT ) in removing smear layer . STUDY DESIGN Forty single-rooted teeth were r and omly divided into 5 test groups and subjected to final irrigation with 17 % EDTA followed by 2.5 % NaOCl for 1 minute each using different activation methods : no activation ( control ) , brushing with NaviTip FX , continuous PUI with irrigant delivered at pulp chamber , continuous PUI with irrigant delivered through the ultrasonic unit , and intermittent PUI . Specimens were examined under scanning electron microscope , and the data were analyzed using Friedman 2-way analysis of variance , Kruskal-Wallis , and Mann-Whitney U tests . RESULTS NaviTip FX and intermittent PUI showed significantly lower smear score than other groups at the 3 mm level ( P < .05 ) . CONCLUSIONS Both brush and intermittent ultrasonic activation were effective in the removal of smear layer from the apical third 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 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 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 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 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 Objective : Micro-leakage , one of the major reasons for recurrent decays , may lead to uncontrollable flow of liquids , pulp inflammation and peri-apical pathology . The purpose of this in vitro study was to evaluate micro-leakage of pit and fissure sealants after using three different pit and fissure preparation techniques : 1 ) acid etching , 2 ) fissure enameloplasty and acid etching , and 3 ) air abrasion and acid etching . Material s and Methods : Sixty-nine extracted sound molars and premolars were r and omly divided into three groups ( 23 sample s in each group ) . Teeth were prepared using one of three occlusal surface treatments . Then the sealant was applied on the occlusal fissures of all teeth . The teeth were thermocycled and stored in normal saline . All teeth were sealed apically and coated with nail varnish and then were immersed in a 2 % solution of methylen blue . Two buccolingual sections were made . The surfaces were scored 0 to 3 for the extent of micro-leakage using a stereomicroscope . Data were analyzed by Kruskal- wallis and Dunn procedure . Results : Enameloplasty and acid etching were significantly different regarding micro-leakage ( P= 0.016 ) , but no significant difference in micro-leakage was observed between air abrasion and the other methods . Conclusion : Enameloplasty followed by acid etching produced significantly less micro-leakage than the acid etching technique . Air abrasion acid etching was better than the acid etching technique in reducing micro-leakage too 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 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 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 ) The presence of the smear layer prevents direct contact between dentine and a dentine adhesive . The use of agents to remove the smear layer theoretically should improve the bonding of composite resins to dentine . This study examined the effect of smear layer removal on the effectiveness of a dentine bonding agent in reducing marginal contraction gaps . The agent used for smear layer removal in this study was ethylenediamine tetra-acetic acid ( EDTA ) .  Eighty cavities measuring 2 mm in diameter and 1.5 mm in depth were prepared in dentine and r and omly assigned to two equal groups . The control group was restored with Prisma Universal Bond 2 Adhesive and Prisma Fil Resin . The experimental group was similarly restored after pretreatment of dentine with 0.5 % EDTA for 60 s. All specimens were thermocycled and the marginal contraction gaps were assessed using a Nikon Measures cope . The mean contraction gap was expressed as a percentage of the cavity diameter . Results showed that the experimental group registered smaller contraction gaps ( mean : 0.021 % ) than the control group ( mean : 0.027 % ) . No penetration of material into dentine was observed . Pretreatment with EDTA did not significantly improve the effectiveness of the dentine bonding agent used in terms of reduction of marginal contraction gaps Three intermediary base material s , a zinc oxide-eugenol ( Cavitec ) and two calcium hydroxide liners ( Life and Dycal ) , were selected at r and om for use as a base beneath  amalgam or composite restorations on humans following complete caries removal .  Life and Dycal , selected at r and om , were also used as direct and indirect pulp capping agents as clinical ly indicated . Clinical evaluations of signs and symptoms were made before treatment and at one-week , six-month , and one-year intervals following treatment . Histological evaluations were performed on three complete caries removal teeth and 18 direct pulp capping teeth six months following treatment . No significant differences in clinical symptomatology result ed between the material s in the complete caries removal group or the indirect and direct pulp capping groups The purpose of this study was to compare intracanal bacterial reduction on teeth instrumented with 0.04 tapered nickel-titanium ( NiTi ) rotary instrumentation to bacterial reduction when using a stainless-steel K-file step-back technique using sterile saline irrigation .  Forty-eight patients with apical periodontitis were r and omly assigned treatment type . The canals were sample d before , during , and after instrumentation . The sample s were incubated anaerobically for 7 days at 37 degrees C , colony-forming unit numbers calculated , and a log transformation performed to normalize the counts . Teeth exhibiting apical periodontitis were uniformly infected , whereas vital control teeth were not . A similar and uniform reduction occurred with progressive filing , regardless of technique ( p < 0.0001 ) . There was no detectable difference in colony-forming unit count after NiTi rotary or stainless-steel h and instrumentation ( p = 0.42 ) . Neither technique could predictably render canals free of bacteria . The results of this study indicate NiTi rotary and stainless-steel h and K-file step-back instrumentation techniques were not significantly different in their ability to reduce intracanal bacteria The purpose of this study was to evaluate the clinical effectiveness of a bioabsorbable membrane made of glycolide and lactide polymers in preserving alveolar ridges following tooth extraction using a surgical technique based on the principles of guided bone regeneration . Sixteen patients requiring extraction s of 2 anterior teeth or bicuspids participated in the study ( split-mouth design ) . Following elevation of buccal and lingual full-thickness flaps and extraction of teeth , experimental sites were covered with bioabsorbable membranes ; control sites did not receive any membrane . Titanium pins served as fixed reference points for measurements . Flaps were advanced in order to achieve primary closure of the surgical wound . No membrane became exposed in the course of healing . Reentry surgeries were performed at 6 months . Results showed that experimental sites presented with significantly less loss of alveolar bone height , more internal socket bone fill , and less horizontal resorption of the alveolar bone ridge . This study suggests that treatment of extraction sockets with membranes made of glycolide and lactide polymers is valuable in preserving alveolar bone in extraction sockets and preventing alveolar ridge defects
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 .