human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: PURPOSE To evaluate whether the hybrid layer significantly contributes to the seal of adhesive Class V restorations placed in vivo and to the bond strength obtained in vitro . MATERIAL S AND METHODS 20 periodontally severely compromised anterior teeth were selected for the leakage study . In each tooth , one round 3 mm wide V-shaped cavity with a maximum depth of 2 mm was prepared on the labial surface crossing the cementum-enamel junction . The sample teeth were r and omly divided into two groups of ten sample s each : in Group 1 , Scotchbond Multi- Purpose Plus was applied in combination with Z-100 following the manufacturer 's instructions . In Group 2 the bonding procedure was the same as in Group 1 , except that after the phosphoric acid treatment , the cavities were treated with 5 % NaOCl for 2 min . Following a period of clinical service of 60 - 90 days , the teeth were extracted and processed for the leakage test . RESULTS At the enamel site , 30 % of the sample s of Group 1 and 70 % of the sample s of Group 2 showed dye penetration . At the dentin site , 50 % of the sample s of Group 1 showed leakage , while all the sample s of Group 2 were severely infiltrated . Statistically significant differences between the groups both for the enamel sites ( P < 0.05 ) and for dentin-cementum sites ( P < 0.001 ) were found . Bond strength tests were performed on 2 mm thick dentin slides of tapered Class I cavities ( n = 10 in each group ) . The mean bond strength value obtained from cavities treated without NaOCl was 15.23 ( + /-1.40 ) MPa and with NaOCl treatment 20.52 ( + /-1.70 ) MPa . Statistical analysis showed significant differences ( P < 0.05 ) between the two groups . No hybrid layer was detected on the NaOCl-treated sample s by scanning electron microscopy 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 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 In light of the in vitro S. sanguis bacterial migration observed deep into root dentin , an in vitro system was developed to determine the viability of these bacteria at the end of migration . Also of interest is whether the smear layer formed during root canal instrumentation modifies migration into root dentinal tubules . Forty-eight bovine root dentin sample s were r and omly split into two groups . Group 1 dentin blocks were not instrumented and were treated with 17 % ethylenediamine tetraacetic acid and 2.5 % sodium hypochlorite for 4 minutes in an ultrasonic bath Group 2 root canals were conventionally instrumented . The smear layer formed was not removed . Dentin blocks were inoculated with a S. sanguis National Collection of Type Culture 7863 suspension . Each sample was immersed in a receiver broth , incubated at 37 degrees C , and checked daily for 14 days . After a 14-day incubation period , group 1 S. sanguis cells remained viable and capable of inoculating the receiver medium after migration through the tubules . Group 2 cells , where the smear layer was intact , revealed an absence of S. sanguis migration in 88 % of the cases . It is therefore plausible that smear layer on canal walls limits S. sanguis penetration of dentinal tubules in vitro 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 Endosonic files are prone to constraint ; this reduces their efficiency , particularly in the apical third and in curved root canals . Precurving the file may reduce constraint , thereby improving the file 's ability to debride . This investigation was undertaken to compare both straight and precurved endosonic files as to debris and smear layer removal .  Thirty-six curved root canals were r and omly allocated into six groups . Each group was prepared using a step-down technique , then instrumented with either a straight or precurved endosonic file of size 15 , 20 , or 25 . The tooth roots were split and examined under the scanning electron microscope . Blind examinations were made for debris and smear layer removal and evaluation scores were analyzed using a log linear approach . The root canals instrumented with the precurved files had a significantly lower debris score than those prepared with straight files . Precurving did not affect smear layer removal . In conclusion , precurving of files decreased the amount of debris but did not affect smear layer removal 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 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 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 ) 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 
    Output:
    
agent
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
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: PURPOSE To evaluate whether the hybrid layer significantly contributes to the seal of adhesive Class V restorations placed in vivo and to the bond strength obtained in vitro . MATERIAL S AND METHODS 20 periodontally severely compromised anterior teeth were selected for the leakage study . In each tooth , one round 3 mm wide V-shaped cavity with a maximum depth of 2 mm was prepared on the labial surface crossing the cementum-enamel junction . The sample teeth were r and omly divided into two groups of ten sample s each : in Group 1 , Scotchbond Multi- Purpose Plus was applied in combination with Z-100 following the manufacturer 's instructions . In Group 2 the bonding procedure was the same as in Group 1 , except that after the phosphoric acid treatment , the cavities were treated with 5 % NaOCl for 2 min . Following a period of clinical service of 60 - 90 days , the teeth were extracted and processed for the leakage test . RESULTS At the enamel site , 30 % of the sample s of Group 1 and 70 % of the sample s of Group 2 showed dye penetration . At the dentin site , 50 % of the sample s of Group 1 showed leakage , while all the sample s of Group 2 were severely infiltrated . Statistically significant differences between the groups both for the enamel sites ( P < 0.05 ) and for dentin-cementum sites ( P < 0.001 ) were found . Bond strength tests were performed on 2 mm thick dentin slides of tapered Class I cavities ( n = 10 in each group ) . The mean bond strength value obtained from cavities treated without NaOCl was 15.23 ( + /-1.40 ) MPa and with NaOCl treatment 20.52 ( + /-1.70 ) MPa . Statistical analysis showed significant differences ( P < 0.05 ) between the two groups . No hybrid layer was detected on the NaOCl-treated sample s by scanning electron microscopy 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 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 In light of the in vitro S. sanguis bacterial migration observed deep into root dentin , an in vitro system was developed to determine the viability of these bacteria at the end of migration . Also of interest is whether the smear layer formed during root canal instrumentation modifies migration into root dentinal tubules . Forty-eight bovine root dentin sample s were r and omly split into two groups . Group 1 dentin blocks were not instrumented and were treated with 17 % ethylenediamine tetraacetic acid and 2.5 % sodium hypochlorite for 4 minutes in an ultrasonic bath Group 2 root canals were conventionally instrumented . The smear layer formed was not removed . Dentin blocks were inoculated with a S. sanguis National Collection of Type Culture 7863 suspension . Each sample was immersed in a receiver broth , incubated at 37 degrees C , and checked daily for 14 days . After a 14-day incubation period , group 1 S. sanguis cells remained viable and capable of inoculating the receiver medium after migration through the tubules . Group 2 cells , where the smear layer was intact , revealed an absence of S. sanguis migration in 88 % of the cases . It is therefore plausible that smear layer on canal walls limits S. sanguis penetration of dentinal tubules in vitro 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 Endosonic files are prone to constraint ; this reduces their efficiency , particularly in the apical third and in curved root canals . Precurving the file may reduce constraint , thereby improving the file 's ability to debride . This investigation was undertaken to compare both straight and precurved endosonic files as to debris and smear layer removal .  Thirty-six curved root canals were r and omly allocated into six groups . Each group was prepared using a step-down technique , then instrumented with either a straight or precurved endosonic file of size 15 , 20 , or 25 . The tooth roots were split and examined under the scanning electron microscope . Blind examinations were made for debris and smear layer removal and evaluation scores were analyzed using a log linear approach . The root canals instrumented with the precurved files had a significantly lower debris score than those prepared with straight files . Precurving did not affect smear layer removal . In conclusion , precurving of files decreased the amount of debris but did not affect smear layer removal 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 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 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 ) 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 
    Output:
    