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: This study reports a prospect i ve clinical trial comparing a carbon fibre reinforced carbon ( CFRC ) endodontic post with a conventional prefabricated post .  Twenty-seven single rooted maxillary anterior teeth in 18 patients ( nine males and nine females ; age range 18 - 60 years ) were restored either with a CFRC post or a wrought precious alloy control . Cast type III gold alloy cores were used in conjunction with both post groups . The CRFC posts ( n = 16 ) were cemented with a composite luting agent and the conventional posts ( control ) were cemented with zinc phosphate . Four failures were recorded in the CFRC post group at 24 , 29 , 56 and 87 months , compared with one failure in the control group at 84 months . These results suggest that post-retained crowns utilizing a CFRC material and a composite resin luting agent do not perform as well as conventional wrought precious alloy posts STATEMENT OF PROBLEM It is unclear which post and core system performs best when bonded to severely compromised endodontically treated teeth . PURPOSE The purpose of this study was to investigate the fracture resistance and mode of failure of severely compromised teeth restored with 3 different adhesively bonded post and core systems . MATERIAL AND METHODS Thirty extracted endodontically treated maxillary anterior teeth were r and omly divided into 3 groups , CPC , gold cast post and core ; TPC , titanium prefabricated post/composite resin core ; and FPC , quartz fiber reinforced post/composite resin core . All posts were adhesively cemented . All cores resembled a central incisor preparation with no remaining tooth structure above the finish line . Cast gold crowns were fabricated and cemented adhesively . The specimens were aged with thermocycling and cyclic loading . Two specimens per group were r and omly selected for micro-computed tomographic imaging before and after aging . Failure was induced with a universal testing machine . The mode of failure was characterized by the interface separation . Data were analyzed with 1-way ANOVA ( α=.05 ) followed by post hoc tests ( Bonferroni ) . RESULTS A statistically significant difference was found among the 3 groups ( P=.002  ) . CPC was significantly different than TPC ( P=.008 ) or FPC ( P=.003 ) . The primary mode of failure  for CPC and TPC  was root fracture , and for FPC post debonding . CONCLUSIONS Severely compromised endodontically treated teeth restored with bonded gold cast post and cores showed significantly higher fracture resistance Glass fiber-reinforced endodontic posts are considered to have favorable mechanical properties for the reconstruction of endodontically treated teeth . The aim of the present investigation was to evaluate the survival of two tapered and one parallel-sided glass fiber-reinforced endodontic post systems in teeth with different stages of hard tissue loss and to identify risk factors for restoration failure . One-hundred and forty-nine glass fiber-reinforced endodontic posts in 122 patients were followed-up for 5 - 56 months [ mean + /- st and ard deviation ( SD ) : 39 + /- 11 months ] . Glass fiber-reinforced endodontic posts were adhesively luted and the core was built with a composite resin .  Cox proportional hazards models were used to evaluate the association of clinical variables and failure rate . Higher failure rates were found for restorations of anterior teeth compared with posterior teeth [ Hazard-Ratios ( HR ) : 3.1 ; 95 % confidence interval ( CI ) : 1.3 - 7.4 ] , for restorations in teeth with no proximal contacts compared with at least one proximal contact ( HR : 3.0 ; 95 % CI : 1.0 - 9.0 ) , and for teeth restored with single crowns compared with fixed bridges ( HR : 4.3 ; 95 % CI : 1.1 - 16.2 ) . Tooth type , type of final restoration and the presence of adjacent teeth were found to be significant predictors of failure rates in endodontically treated teeth restored with glass fiber-reinforced endodontic posts AIM To assess survival rates and complications of  root-filled teeth restored with or without post- and -core systems  over a mean observation period of > or=4 years . METHODOLOGY A total of 325 single- and multirooted teeth in 183 subjects treated in a private practice were root filled and restored with either a cast post- and -core or with a prefabricated titanium post and composite core . Root-filled teeth without post-retained restorations served as controls . The restored teeth served as abutments for single unit metal-ceramic or composite crowns or fixed bridges . Teeth supporting cantilever bridges , overdentures or telescopic crowns were excluded . RESULTS Seventeen teeth in 17 subjects were lost to follow-up ( 17/325 : 5.2 % ) . The mean observation period was 5.2 + /- 1.8 ( SD ) years for restorations with titanium posts , 6.2 + /- 2.0 ( SD ) years for cast post- and -cores and 4.4 + /- 1.7 ( SD ) years for teeth without posts . Overall , 54 % of build-ups included the incorporation of a titanium post and 26.5 % the cementation of a cast post- and -core . The remaining 19.5 % of the teeth were restored without intraradicular retention . The adjusted 5-year tooth survival rate amounted to 92.5 % for teeth restored with titanium posts , to 97.1 % for teeth restored with cast post- and -cores and to 94.3 % for teeth without post restorations , respectively . The most frequent complications included root fracture ( 6.2 % ) , recurrent caries ( 1.9 % ) , post-treatment periradicular disease ( 1.6 % ) and loss of retention ( 1.3 % ) . CONCLUSION Provided that high- quality root canal treatment and restorative protocol s are implemented , high survival and low complication rates of single- and multirooted root-filled teeth used as abutments for fixed restorations can be expected after a mean observation period of > or=4 years PURPOSE This study prospect ively evaluated the clinical performance of three types of translucent posts over a follow-up period of between 2 and 3 years . MATERIAL S AND METHODS Selected were 225 patients with one premolar in need of endodontic treatment , followed by restoration with a fiber post and porcelain crown .  The sample was r and omly divided into three groups of 75 patients each . The same type of post was used in all patients within a group : group 1 = Aesthetic Plus ; group 2 = DT ; and group 3 = FRC Postec . For bonding the post , a light-curing adhesive ( One-Step ) and a dual-curing resin cement ( Duo-Link ) were applied in group 1 and 2 roots , whereas self-curing material s ( Excite DSC as adhesive and MultiLink as resin cement ) were used in group 3 . After 6 , 12 , and 24 months , patients were recalled , and a clinical and radiographic examination was performed . For some patients , 30-month follow-up data were also collected . RESULTS Debonding of the post occurrred in eight cases ( 3.5 % ) ; in another six cases , a recurrence of the periapical lesion was reported . CONCLUSION The statistical analysis did not reveal any significant difference in the survival rate of the tested posts , suggesting that all are equally and sufficiently reliable for clinical use PURPOSE In the present prospect i ve study , four different post- and -core systems were evaluated over a period of up to 10 years . MATERIAL S AND METHODS Fifty endodontically treated teeth in 31 patients were r and omized to one of four groups for post- and -core placement : Group 1 received conventional tapered cast posts and cores ( n = 14 ) ; group 2 received ParaPost system prefabricated gold posts with cast cores ( n = 13 ) ; group 3 received ParaPost system cast posts and cores ( n = 13 ) ; and group 4 received Radix-Anchor posts ( n = 10 ) . Clinical and radiologic evaluations were made . RESULTS One post and core in group 2 was functioning well 58 months after placement when the patient died . No posts and cores in groups 1 or 2 had been lost or had any complications , one in group 3 had been lost because of a root fracture after 108 months , and two in group 4 had been lost after 54 and 88 months , respectively , because of loss of retention . The final treatment result for 46 of the 49 remaining posts ( 30 patients ) was successful . The overall failure rate was 6 % . There were no statistically significant differences between the four groups . CONCLUSION If recommended procedures are strictly followed , posts and cores can serve as abutments for fixed single crowns with satisfactory long-term results PURPOSE To determine , in a 3-year clinical trial , whether tooth type and ferrule significantly affect the survival of pulpless teeth restored with fiber posts . METHODS A sample of 87 teeth in 87 patients ( 32 men and 55 women , age ranged from 23 to 78 ) were restored using Snowpost : 34 incisors , 12 canines , 25 premolars and 16 molars . The posts were cemented with RelyXUnicem and the core was made with a resin composite ( Dentocore Automix ) . Every tooth was covered with a metal-ceramic or all ceramic crown . Two experimental groups , according to the presence or absence of ferrule , were defined : A ) 45 teeth with ferrule ( > 2 mm height ) ; and B ) 42 teeth without ferrule ( < 2 mm height ) . Patients were reevaluated every 6 months . RESULTS 14 of the total restorations failed ( 16.1 % ) . The failure modes were caries ( n=4 ) , post fracture ( n=4 ) , root fracture ( n=2 ) , and marginal gap , post cement failure , crown cement failure , and periapical lesion ( n= 1 respectively ) . In Group A the failure observed was 6.67 % and in Group B it was 26.20 % . The log-rank test showed statistically significant differences between both groups . According to the type of tooth , the incisors were the teeth with the highest failure rate ( 73.52 % ) , but Chi-square test showed no statistically significant differences among the four tooth types , perhaps because of the low number of the sample PURPOSE This controlled clinical trial aim ed to compare the 3-year outcomes of glass fiber posts and composite cores with gold alloy-based posts and cores for the restoration of endodontically treated teeth . MATERIAL S AND METHODS One hundred forty-four patients in need of 205 restorations on endodontically treated teeth were selected and followed for 7 to 37 months ( mean : 21 ± 9 months ) . The teeth were primarily stratified based on the remaining tissue available to restore the tooth core with or without a post . Then , r and omization allocated the teeth to either test group 1 ( prefabricated glass fiber posts ) , test group 2 ( custom-made glass fiber posts ) , or test group 3 ( composite cores without posts ) . The control group consisted of gold alloy-based posts and cores . All posts/cores were covered with all-ceramic single crowns .  Failures were either absolute , such as root fractures or irreparable fractures of the post/core , or relative , such as loss of post retention or reparable fractures of the core . Success and survival probability lifetime curves , corrected for clustering , were drawn for the entire data set . RESULTS The recall rate at 3 years was 97.1 % . Absolute failures consisted of two root fractures and one endodontic failure , while relative failures included three instances of retention loss of the post/core and one post fracture . Because of the low number of events , no statistical tests were performed . The success and survival probabilities over all groups together at 3 years amounted to 91.7 % and 97.2 % , respectively . CONCLUSIONS After being followed for up to 3 years , both cast gold and composite post and core systems performed well clinical ly . Longer follow-up times are needed to detect possible significant differences . Int J Prosthodont 2011;24:363 - 372 OBJECTIVE To assess the survival rate of two different post systems after 5 years of service with a prospect i ve r and omized controlled trial . METHOD AND MATERIAL S One hundred patients in need of a post were studied . Half of the patients received long glass fiber-reinforced posts , while the other half received long metal screw posts . The posts were assigned r and omly . After at least 5 years ( mean , 61.37 months ) , follow-ups were established . When a complication occurred prior to this recall , the type and time of the complication was documented . Statistical analysis was performed using the log-rank test and Kaplan-Meier analysis . Additionally , a Cox regression was performed to analyze risk factors . RESULTS The survival rate of fiber-reinforced posts was 71.8 % . In the metal screw post group , the survival rate was significantly lower , 50.0 % ( log-rank test , P = .026 ) . Metal posts result ed more often in more unfavorable complications ( eg , root fractures ) ; consequently , more teeth ( n = 17 ) had to be extracted . The Cox regression identified the following risk factors : position of the tooth ( anterior vs posterior teeth ) , degree of coronal tooth destruction , and the post system  ( fiber-reinforced post vs metal screw post )  . Fiber-reinforced restorations loosened in several patients ; in some of these cases ( n = 6 ) , patients did not notice this , leading to the extraction of teeth . CONCLUSION Long metal screw posts should be used with great care in endodontically treated teeth . Besides the selection 
    Output:
    
agent
Failures of fiber posts were mainly due to post loss of retention , while metal post failures were mostly related to root fracture , post fracture and crown and /or post loss of retention .
In conclusion , metal and fiber posts present similar clinical behavior at short to medium term follow-up .
Remaining dental structure and ferrule increase the survival of restored pulpless teeth .
***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: This study reports a prospect i ve clinical trial comparing a carbon fibre reinforced carbon ( CFRC ) endodontic post with a conventional prefabricated post .  Twenty-seven single rooted maxillary anterior teeth in 18 patients ( nine males and nine females ; age range 18 - 60 years ) were restored either with a CFRC post or a wrought precious alloy control . Cast type III gold alloy cores were used in conjunction with both post groups . The CRFC posts ( n = 16 ) were cemented with a composite luting agent and the conventional posts ( control ) were cemented with zinc phosphate . Four failures were recorded in the CFRC post group at 24 , 29 , 56 and 87 months , compared with one failure in the control group at 84 months . These results suggest that post-retained crowns utilizing a CFRC material and a composite resin luting agent do not perform as well as conventional wrought precious alloy posts STATEMENT OF PROBLEM It is unclear which post and core system performs best when bonded to severely compromised endodontically treated teeth . PURPOSE The purpose of this study was to investigate the fracture resistance and mode of failure of severely compromised teeth restored with 3 different adhesively bonded post and core systems . MATERIAL AND METHODS Thirty extracted endodontically treated maxillary anterior teeth were r and omly divided into 3 groups , CPC , gold cast post and core ; TPC , titanium prefabricated post/composite resin core ; and FPC , quartz fiber reinforced post/composite resin core . All posts were adhesively cemented . All cores resembled a central incisor preparation with no remaining tooth structure above the finish line . Cast gold crowns were fabricated and cemented adhesively . The specimens were aged with thermocycling and cyclic loading . Two specimens per group were r and omly selected for micro-computed tomographic imaging before and after aging . Failure was induced with a universal testing machine . The mode of failure was characterized by the interface separation . Data were analyzed with 1-way ANOVA ( α=.05 ) followed by post hoc tests ( Bonferroni ) . RESULTS A statistically significant difference was found among the 3 groups ( P=.002  ) . CPC was significantly different than TPC ( P=.008 ) or FPC ( P=.003 ) . The primary mode of failure  for CPC and TPC  was root fracture , and for FPC post debonding . CONCLUSIONS Severely compromised endodontically treated teeth restored with bonded gold cast post and cores showed significantly higher fracture resistance Glass fiber-reinforced endodontic posts are considered to have favorable mechanical properties for the reconstruction of endodontically treated teeth . The aim of the present investigation was to evaluate the survival of two tapered and one parallel-sided glass fiber-reinforced endodontic post systems in teeth with different stages of hard tissue loss and to identify risk factors for restoration failure . One-hundred and forty-nine glass fiber-reinforced endodontic posts in 122 patients were followed-up for 5 - 56 months [ mean + /- st and ard deviation ( SD ) : 39 + /- 11 months ] . Glass fiber-reinforced endodontic posts were adhesively luted and the core was built with a composite resin .  Cox proportional hazards models were used to evaluate the association of clinical variables and failure rate . Higher failure rates were found for restorations of anterior teeth compared with posterior teeth [ Hazard-Ratios ( HR ) : 3.1 ; 95 % confidence interval ( CI ) : 1.3 - 7.4 ] , for restorations in teeth with no proximal contacts compared with at least one proximal contact ( HR : 3.0 ; 95 % CI : 1.0 - 9.0 ) , and for teeth restored with single crowns compared with fixed bridges ( HR : 4.3 ; 95 % CI : 1.1 - 16.2 ) . Tooth type , type of final restoration and the presence of adjacent teeth were found to be significant predictors of failure rates in endodontically treated teeth restored with glass fiber-reinforced endodontic posts AIM To assess survival rates and complications of  root-filled teeth restored with or without post- and -core systems  over a mean observation period of > or=4 years . METHODOLOGY A total of 325 single- and multirooted teeth in 183 subjects treated in a private practice were root filled and restored with either a cast post- and -core or with a prefabricated titanium post and composite core . Root-filled teeth without post-retained restorations served as controls . The restored teeth served as abutments for single unit metal-ceramic or composite crowns or fixed bridges . Teeth supporting cantilever bridges , overdentures or telescopic crowns were excluded . RESULTS Seventeen teeth in 17 subjects were lost to follow-up ( 17/325 : 5.2 % ) . The mean observation period was 5.2 + /- 1.8 ( SD ) years for restorations with titanium posts , 6.2 + /- 2.0 ( SD ) years for cast post- and -cores and 4.4 + /- 1.7 ( SD ) years for teeth without posts . Overall , 54 % of build-ups included the incorporation of a titanium post and 26.5 % the cementation of a cast post- and -core . The remaining 19.5 % of the teeth were restored without intraradicular retention . The adjusted 5-year tooth survival rate amounted to 92.5 % for teeth restored with titanium posts , to 97.1 % for teeth restored with cast post- and -cores and to 94.3 % for teeth without post restorations , respectively . The most frequent complications included root fracture ( 6.2 % ) , recurrent caries ( 1.9 % ) , post-treatment periradicular disease ( 1.6 % ) and loss of retention ( 1.3 % ) . CONCLUSION Provided that high- quality root canal treatment and restorative protocol s are implemented , high survival and low complication rates of single- and multirooted root-filled teeth used as abutments for fixed restorations can be expected after a mean observation period of > or=4 years PURPOSE This study prospect ively evaluated the clinical performance of three types of translucent posts over a follow-up period of between 2 and 3 years . MATERIAL S AND METHODS Selected were 225 patients with one premolar in need of endodontic treatment , followed by restoration with a fiber post and porcelain crown .  The sample was r and omly divided into three groups of 75 patients each . The same type of post was used in all patients within a group : group 1 = Aesthetic Plus ; group 2 = DT ; and group 3 = FRC Postec . For bonding the post , a light-curing adhesive ( One-Step ) and a dual-curing resin cement ( Duo-Link ) were applied in group 1 and 2 roots , whereas self-curing material s ( Excite DSC as adhesive and MultiLink as resin cement ) were used in group 3 . After 6 , 12 , and 24 months , patients were recalled , and a clinical and radiographic examination was performed . For some patients , 30-month follow-up data were also collected . RESULTS Debonding of the post occurrred in eight cases ( 3.5 % ) ; in another six cases , a recurrence of the periapical lesion was reported . CONCLUSION The statistical analysis did not reveal any significant difference in the survival rate of the tested posts , suggesting that all are equally and sufficiently reliable for clinical use PURPOSE In the present prospect i ve study , four different post- and -core systems were evaluated over a period of up to 10 years . MATERIAL S AND METHODS Fifty endodontically treated teeth in 31 patients were r and omized to one of four groups for post- and -core placement : Group 1 received conventional tapered cast posts and cores ( n = 14 ) ; group 2 received ParaPost system prefabricated gold posts with cast cores ( n = 13 ) ; group 3 received ParaPost system cast posts and cores ( n = 13 ) ; and group 4 received Radix-Anchor posts ( n = 10 ) . Clinical and radiologic evaluations were made . RESULTS One post and core in group 2 was functioning well 58 months after placement when the patient died . No posts and cores in groups 1 or 2 had been lost or had any complications , one in group 3 had been lost because of a root fracture after 108 months , and two in group 4 had been lost after 54 and 88 months , respectively , because of loss of retention . The final treatment result for 46 of the 49 remaining posts ( 30 patients ) was successful . The overall failure rate was 6 % . There were no statistically significant differences between the four groups . CONCLUSION If recommended procedures are strictly followed , posts and cores can serve as abutments for fixed single crowns with satisfactory long-term results PURPOSE To determine , in a 3-year clinical trial , whether tooth type and ferrule significantly affect the survival of pulpless teeth restored with fiber posts . METHODS A sample of 87 teeth in 87 patients ( 32 men and 55 women , age ranged from 23 to 78 ) were restored using Snowpost : 34 incisors , 12 canines , 25 premolars and 16 molars . The posts were cemented with RelyXUnicem and the core was made with a resin composite ( Dentocore Automix ) . Every tooth was covered with a metal-ceramic or all ceramic crown . Two experimental groups , according to the presence or absence of ferrule , were defined : A ) 45 teeth with ferrule ( > 2 mm height ) ; and B ) 42 teeth without ferrule ( < 2 mm height ) . Patients were reevaluated every 6 months . RESULTS 14 of the total restorations failed ( 16.1 % ) . The failure modes were caries ( n=4 ) , post fracture ( n=4 ) , root fracture ( n=2 ) , and marginal gap , post cement failure , crown cement failure , and periapical lesion ( n= 1 respectively ) . In Group A the failure observed was 6.67 % and in Group B it was 26.20 % . The log-rank test showed statistically significant differences between both groups . According to the type of tooth , the incisors were the teeth with the highest failure rate ( 73.52 % ) , but Chi-square test showed no statistically significant differences among the four tooth types , perhaps because of the low number of the sample PURPOSE This controlled clinical trial aim ed to compare the 3-year outcomes of glass fiber posts and composite cores with gold alloy-based posts and cores for the restoration of endodontically treated teeth . MATERIAL S AND METHODS One hundred forty-four patients in need of 205 restorations on endodontically treated teeth were selected and followed for 7 to 37 months ( mean : 21 ± 9 months ) . The teeth were primarily stratified based on the remaining tissue available to restore the tooth core with or without a post . Then , r and omization allocated the teeth to either test group 1 ( prefabricated glass fiber posts ) , test group 2 ( custom-made glass fiber posts ) , or test group 3 ( composite cores without posts ) . The control group consisted of gold alloy-based posts and cores . All posts/cores were covered with all-ceramic single crowns .  Failures were either absolute , such as root fractures or irreparable fractures of the post/core , or relative , such as loss of post retention or reparable fractures of the core . Success and survival probability lifetime curves , corrected for clustering , were drawn for the entire data set . RESULTS The recall rate at 3 years was 97.1 % . Absolute failures consisted of two root fractures and one endodontic failure , while relative failures included three instances of retention loss of the post/core and one post fracture . Because of the low number of events , no statistical tests were performed . The success and survival probabilities over all groups together at 3 years amounted to 91.7 % and 97.2 % , respectively . CONCLUSIONS After being followed for up to 3 years , both cast gold and composite post and core systems performed well clinical ly . Longer follow-up times are needed to detect possible significant differences . Int J Prosthodont 2011;24:363 - 372 OBJECTIVE To assess the survival rate of two different post systems after 5 years of service with a prospect i ve r and omized controlled trial . METHOD AND MATERIAL S One hundred patients in need of a post were studied . Half of the patients received long glass fiber-reinforced posts , while the other half received long metal screw posts . The posts were assigned r and omly . After at least 5 years ( mean , 61.37 months ) , follow-ups were established . When a complication occurred prior to this recall , the type and time of the complication was documented . Statistical analysis was performed using the log-rank test and Kaplan-Meier analysis . Additionally , a Cox regression was performed to analyze risk factors . RESULTS The survival rate of fiber-reinforced posts was 71.8 % . In the metal screw post group , the survival rate was significantly lower , 50.0 % ( log-rank test , P = .026 ) . Metal posts result ed more often in more unfavorable complications ( eg , root fractures ) ; consequently , more teeth ( n = 17 ) had to be extracted . The Cox regression identified the following risk factors : position of the tooth ( anterior vs posterior teeth ) , degree of coronal tooth destruction , and the post system  ( fiber-reinforced post vs metal screw post )  . Fiber-reinforced restorations loosened in several patients ; in some of these cases ( n = 6 ) , patients did not notice this , leading to the extraction of teeth . CONCLUSION Long metal screw posts should be used with great care in endodontically treated teeth . Besides the selection 
    Output:
    