***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 compare by confocal and scanning electron microscopy the post-resin-dentin interfaces of endodontically-treated teeth which had been restored with dentin-bonding systems and composite and needed to be extracted after 6 months to 6 years of clinical service . MATERIAL S AND METHODS Sixteen single rooted teeth showing proximal lesions penetrating the pulp chamber were included in the investigation and divided into two groups . Group 1 teeth were endodontically-treated , restored with carbon fiber posts and resin-based composite . Group 2 teeth were treated in the same way and covered with porcelain fused-to-metal crowns . RESULTS Two thirds of the observed interfaces showed resin penetration of the root dentin in the middle and coronal third of the post space preparation , while only one third of the interface showed resin infiltration in the apical third of the post space preparation . Debonding of the adhesive from the resin infiltrated dentin area and debonding of the composite cement from the adhesive were the most frequently observed failure modes and were observed in one third of the observed interfaces . There was no difference between the post-resin-dentin interfaces of teeth covered and teeth not covered with porcelain-fused to metal crowns . Teeth extracted after longer periods of clinical service showed more abundant areas of debonding of the adhesive from the resin-dentin interdiffusion zone . The presence of bacteria in resin infiltrated dentin tubules was observed in two specimens STATEMENT OF PROBLEM Crowns have been considered the restoration of choice for endodontically treated teeth , but their selection has been based primarily on anecdotal evidence . PURPOSE This study tested the hypothesis that crown placement ( coronal coverage ) is associated with improved survival of endodontically treated teeth when preaccess , endodontic , and restorative factors are controlled . MATERIAL AND METHODS A University of Iowa College of Dentistry treatment data base was used to identify permanent teeth that had undergone initial obturation between July 1 , 1985 , and December 31 , 1987 . Study patients were restricted to persons with at least 1 dental visit in each 2-year interval from 1985 to 1996 ; a simple r and om sample of 280 patients ( n = 400 teeth ) was selected . Dental charts , radiographs , and computerized data bases were examined to ascertain variables of interest and to verify study inclusion criteria . Kaplan-Meier survival estimates were generated for the 203 teeth that satisfied study inclusion criteria . Multivariate Cox proportional hazards regression models were developed , with st and ard errors adjusted to account for clustering of teeth within patients . RESULTS When tooth type and radiographic evidence of caries at access were controlled , the final Cox model showed that endodontically treated teeth not crowned after obturation were lost at a 6.0 times greater rate than teeth crowned after obturation ( 95 % confidence interval : 3.2 to 11.3 ) . CONCLUSION Within the limitations of this study , a strong association between crown placement and the survival of endodontically treated teeth was observed . These results may impact treatment planning if long-term tooth retention is the primary goal STATEMENT OF PROBLEM Little information exists regarding the outcome of crown build-ups on endodontically treated teeth restored with metal-ceramic crowns or with only a direct-placed composite . PURPOSE The aim of this study was to evaluate the clinical success rate of endodontically treated premolars restored with fiber posts and direct composite restorations and compare that treatment with a similar treatment of full-coverage with metal-ceramic crowns . MATERIAL AND METHODS Subjects included in this study had one maxillary or m and ibular premolar for which endodontic treatment and crown build up was indicated and met specific inclusion /exclusion criteria . Only premolars with Class II carious lesions and preserved cusp structure were included . Subjects were r and omly assigned to 1 of the following 2 experimental groups : ( 1 ) teeth endodontically treated and restored with adhesive techniques and composite or ( 2 ) teeth endodontically treated , restored with adhesive techniques and composite , and then restored with full-coverage metal-ceramic crowns .  Sixty teeth were included in the first group and 57 in the second . All restorations were performed by one operator . Causes of failure were categorized as root fracture , post fracture , post decementation , clinical and /or radiographic evidence of marginal gap between tooth and restoration , and clinical and /or radiographic evidence of secondary caries contiguous with restoration margins . Subjects were examined for the listed clinical and radiographic causes of failure by 2 calibrated examiners at intervals of 1 , 2 , and 3 years . Exact 95 % confidence intervals for the difference between the 2 experimental groups were calculated . RESULTS At the 1-year recall , no failures were reported . The only failure modes observed at 2 and 3 years were decementations of posts and clinical and /or radiographic evidence of marginal gap between tooth and restoration . There was no difference in the failure frequencies of the 2 groups ( 95 % confidence interval , -17.5 to 12.6 ) . There was no difference between the number of failures caused by post decementations and the presence of marginal gaps observed in the 2 groups ( 95 % confidence intervals , -9.7 to 16.2 and -17.8 to 9.27 ) . CONCLUSION Within the limitations of this study , the results upheld the research hypothesis that the clinical success rates of endodontically treated premolars restored with fiber posts and direct composite restorations after 3 years of service were equivalent to a similar treatment of full coverage with metal-ceramic crowns PURPOSE The aim of this long-term follow-up study was to collect up to 17 years of survival data of endodontically treated single teeth with or without a prefabricated metal post .  MATERIAL S AND METHODS Single teeth were provided with direct composite resin core-crown reconstructions with or without posts by 15 operators . Restorations consisted of either a prefabricated metal post and a composite core-crown reconstruction or a post-free direct composite reconstruction . Allocation of either restoration was performed by balanced drawing . These restorations were not covered by an artificial crown . The study sample consisted of 87 patients who received 98 core-crown reconstructions .  The performance of the restorations was evaluated based on data collected from the files of the clinicians currently monitoring the oral health of the patients . The survival probability was analyzed at different levels : on the restoration level and on the level of the tooth carrying the restoration . Kaplan-Meier analysis was used to compare survival probabilities . RESULTS Post placement showed no influence on the survival probability at either level ( P > .05 ) . The estimated overall survival rate at 17 years was 53 % + /- 14 % at the restoration level and 79 % + /- 11 % at the tooth level . CONCLUSION The results of this long-term follow-up study showed no difference in survival probabilities between different direct composite resin core-crown reconstructions of endodontically treated single teeth ( with or without a post ) The CONSORT statement is used worldwide to improve the reporting of r and omised controlled trials . Kenneth Schulz and colleagues describe the latest version , CONSORT 2010 , which up date s the reporting guideline based on new method ological evidence and accumulating experience . To encourage dissemination of the CONSORT 2010 Statement , this article is freely accessible on bmj.com and will also be published in the Lancet , Obstetrics and Gynecology , PLoS Medicine , Annals of Internal Medicine , Open Medicine , Journal of Clinical Epidemiology , BMC Medicine , and Trials 
    Output:
    
There is insufficient evidence to support or refute the effectiveness of conventional fillings over crowns for the restoration of root filled teeth .