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 This study compares the survival rate and fracture strength of endodontically treated maxillary incisors with moderate coronal defects restored with different post- and -core systems after exposure to an artificial mouth . MATERIAL S AND METHODS Sixty-four caries-free human maxillary central incisors were selected for st and ardized size and quality , endodontically treated , and decoronated 2 mm coronal to the cementoenamel junction . Group 1 was restored with titanium posts and composite cores , group 2 received zirconia posts and a composite core , and in group 3 zirconia posts with a heat-pressed ceramic core were used . Teeth restored with cast posts and cores served as controls . All teeth were prepared and restored with complete cast crowns . All sample s were exposed to 1.2 million cycles in a computer-controlled chewing simulator with simultaneous thermocycling . In addition , the sample s were loaded until fracture in a static testing device . RESULTS The survival rates of the different groups were : 94 % for titanium/composite , 63 % for zirconia/composite , 100 % for the all-ceramic post and core , and 94 % for the cast post and core . The following mean fracture strengths were obtained : titanium/composite = 425 + /- 155 N , zirconia/composite = 202 + /- 212 N , zirconia/ceramic = 378 + /- 64 N , cast post and core = 426 + /- 178 N. The lower fracture load in the group with zirconia posts and composite cores was statistically significant . The use of zirconia posts result ed in fewer oblique root fractures . CONCLUSION Prefabricated titanium posts with composite cores , zirconia posts with heat-pressed ceramic cores , and cast posts and cores yield comparable survival rates and fracture strengths for the restoration of crowned maxillary incisors with moderate coronal defects .  Survival rates and fracture strengths for zirconia posts with composite cores are significantly lower , so this combination can not be recommended for clinical use STATEMENT OF PROBLEM A self-contained post and core system , Composipost , comprising an epoxy-based carbon fiber post , a composite core material , and a low viscosity Bis-GMA bonding resin , has recently been marketed for the restoration of pulpless teeth . PURPOSE This study compared the in vitro performance and the failure characteristics of the Composipost system against existing post and core combinations . MATERIAL AND METHODS Using extracted human teeth , three post and core test groups and one control group were then tested to failure with an obliquely applied compressive load at 130 degrees in a Hounsfield testing-machine with a crosshead speed of 5 cm/minute . RESULTS The mean stress values at failure ( MNm.2 ) with st and ard deviations for each group were as follows : Composipost system 8.89 , SD 2.40 ; stainless steel post and composite core 14.18 , SD 3.49 ; cast gold alloy post and gold alloy core 15.25 , SD 4.07 ; and endodontically treated tooth only 24.84 SD 4.58 . CONCLUSION The specimens restored with the Composipost system exhibited inferior strength properties in comparison to the other post and core systems tested ( p < 0.01 ) . Teeth without post and core foundations tested significantly stronger than the other comparison groups ( p < 0.01 ) 
    Output:
    
agent
A comparison of fracture loads in the in vitro studies revealed no significant difference between cast and direct posts and cores .
Meta- analysis of the data suggested that there is no difference in fracture behavior associated with the 2 treatment modalities .
***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 This study compares the survival rate and fracture strength of endodontically treated maxillary incisors with moderate coronal defects restored with different post- and -core systems after exposure to an artificial mouth . MATERIAL S AND METHODS Sixty-four caries-free human maxillary central incisors were selected for st and ardized size and quality , endodontically treated , and decoronated 2 mm coronal to the cementoenamel junction . Group 1 was restored with titanium posts and composite cores , group 2 received zirconia posts and a composite core , and in group 3 zirconia posts with a heat-pressed ceramic core were used . Teeth restored with cast posts and cores served as controls . All teeth were prepared and restored with complete cast crowns . All sample s were exposed to 1.2 million cycles in a computer-controlled chewing simulator with simultaneous thermocycling . In addition , the sample s were loaded until fracture in a static testing device . RESULTS The survival rates of the different groups were : 94 % for titanium/composite , 63 % for zirconia/composite , 100 % for the all-ceramic post and core , and 94 % for the cast post and core . The following mean fracture strengths were obtained : titanium/composite = 425 + /- 155 N , zirconia/composite = 202 + /- 212 N , zirconia/ceramic = 378 + /- 64 N , cast post and core = 426 + /- 178 N. The lower fracture load in the group with zirconia posts and composite cores was statistically significant . The use of zirconia posts result ed in fewer oblique root fractures . CONCLUSION Prefabricated titanium posts with composite cores , zirconia posts with heat-pressed ceramic cores , and cast posts and cores yield comparable survival rates and fracture strengths for the restoration of crowned maxillary incisors with moderate coronal defects .  Survival rates and fracture strengths for zirconia posts with composite cores are significantly lower , so this combination can not be recommended for clinical use STATEMENT OF PROBLEM A self-contained post and core system , Composipost , comprising an epoxy-based carbon fiber post , a composite core material , and a low viscosity Bis-GMA bonding resin , has recently been marketed for the restoration of pulpless teeth . PURPOSE This study compared the in vitro performance and the failure characteristics of the Composipost system against existing post and core combinations . MATERIAL AND METHODS Using extracted human teeth , three post and core test groups and one control group were then tested to failure with an obliquely applied compressive load at 130 degrees in a Hounsfield testing-machine with a crosshead speed of 5 cm/minute . RESULTS The mean stress values at failure ( MNm.2 ) with st and ard deviations for each group were as follows : Composipost system 8.89 , SD 2.40 ; stainless steel post and composite core 14.18 , SD 3.49 ; cast gold alloy post and gold alloy core 15.25 , SD 4.07 ; and endodontically treated tooth only 24.84 SD 4.58 . CONCLUSION The specimens restored with the Composipost system exhibited inferior strength properties in comparison to the other post and core systems tested ( p < 0.01 ) . Teeth without post and core foundations tested significantly stronger than the other comparison groups ( p < 0.01 ) 
    Output:
    