***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: A total of 264 implants was placed in 143 patients using different immediate or delayed-immediate implant placement techniques in 12 different centers participating in a prospect i ve multicenter study . The reason for tooth extraction was evaluated ; bone quality and quantity were classified ; socket depths were registered ; and data on implant type , size , and position were collected . One hundred thirty-nine suprastructures were placed on 228 implants in 126 patients . A follow-up evaluation was done on 125 patients after 1 year of loading and on 107 patients after 3 years of loading . Clinical parameters ( bleeding or not bleeding , pocket depth , and implant mobility ) were evaluated after 1 and 3 years , and the marginal bone level after 1 year of loading was measured on radiographs . Clinical comparisons were performed to evaluate implant loss in relation to implant type , size , position , bone quality and quantity , socket depth , reason for tooth extraction , and placement method . In addition , life table analysis was done for cumulative implant survival rates . There was no clinical difference with respect to socket depth or when comparing the different placement methods . A higher failure rate was found for short implants in the posterior region of the maxilla and when periodontitis was cited as a reason for tooth extraction . Mean marginal bone resorption from the time of loading to the 1-year follow-up was 0.8 mm in the maxilla and 0.5 mm in the m and ible . Over a period of 3 years , the implant survival rate was 92.4 % in the maxilla and 94.7 % in the m and ible 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 BACKGROUND Numerous investigators have used osseointegrated dental implants as retention for m and ibular overdentures , but few have reported 10-year outcomes or incorporated carefully st and ardized radiographs to document crestal bone loss . PURPOSE The purpose of this study was to use a prospect i ve clinical trial design to assess the performance of short sintered porous-surfaced dental implants with a m and ibular complete overdenture when all patients in the trial had undergone 10 years of continuous function . MATERIAL S AND METHODS Fifty-two fully edentulous patients , most with advanced alveolar ridge resorption , each received three free-st and ing Endopore implants ( 7 - 10 mm in length , mean length , 8.7 mm ; Innova Corporation , Toronto , ON , Canada ) in the m and ibular symphysis region . After 10 weeks of submerged healing , these implants were used to support an overdenture . Carefully st and ardized radiographs , using a customized stainless steel filmholder attached to each implant and the x-ray tube , were collected at baseline , 3 months , 6 months , yearly to 5 years , and then again at 7 and 10 years . RESULTS Life table analysis revealed a 10-year implant survival of 92.7 % and a mean annual bone loss after year 1 of 0.03 mm . CONCLUSION Short free-st and ing dental implants with a sintered porous surface used for implant fixation are a predictable and effective means of retaining a m and ibular overdenture in patients with advanced m and ibular ridge resorption BACKGROUND Health risks associated with smoking have been exhaustively documented and include increased incidence of periodontal disease , greater risk of osteitis following oral surgery , and compromised wound healing due to hypoxia . Information related directly to dental implants , although limited , points to higher rates of implant failures among smokers than non-smokers . This paper reports on long-term clinical outcomes of osseointegrated dental implants placed in smokers and non-smokers in a longitudinal clinical study of endosseous dental implants . METHODS In 1990 , the Dental Implant Clinical Research Group ( DICRG ) of the Department of Veterans Affairs ( DVA ) launched an 8-year , r and omized , prospect i ve clinical study of more than 2,900 endosseous dental implants in more than 800 patients at 32 study centers . Confounding variables , including smoking patterns , were recorded . For this report , new follow-up data were analyzed for two groups : 1 ) current smokers and 2 ) those who never smoked combined with those who quit . Most of the variables recorded for each implant were screened on a univariate basis as possible predictors associated with implant survival/failure . Those with P values less than 0.15 and those likely to be a factor of clinical importance were placed in a logistic regression equation and analyzed for a simultaneous effect on survival . A step-wise procedure was used to eliminate those variables that showed the least significance , until only those variables with a Wald chi-square of significance in the presence of others remained . The effects of clustering within patients and of unbalanced distribution within hospitals were st and ardized to facilitate analysis of influence of demographic variables . The GEE analysis was performed with the patient as the primary cluster . RESULTS Current data do not support earlier findings that smoking contributes to early implant failure ( placement to uncovering ) . A trend of greater failures in smokers appeared between the time after uncovering and before insertion of the prosthesis . Hydroxyapatite (HA)-coated implants had significantly lower failure rates . For the entire 3-year period , overall failures were significantly higher for smokers than non-smokers . CONCLUSIONS Results suggest that increased implant failures in smokers are not the result of poor healing or osseointegration , but of exposure of peri-implant tissues to tobacco smoke . Data also suggest that detrimental effects may be reduced by : 1 ) cessation of smoking ; 2 ) the use of preoperative antibiotics ; and 3 ) the use of HA-coated implants OBJECTIVE Many biological variables , endodontic treatment factors , and restorative considerations have been suggested in the literature to affect the outcome of endodontic treatment . However , few attempts have been made recently to study these variables further . The purpose of this study was to identify the biologic and endodontic treatment-associated variables that are most predictive of treatment outcome for conventional endodontic therapy and to determine the magnitude of risk these variables pose on the outcome . STUDY DESIGN The population of this historical prospect i ve cohort study comprised a total of 200 teeth with 441 root canals . Diagnostic and treatment information was abstract ed from the original patient records . An endodontic follow-up examination was conducted 4 + /- 0.5 years after obturation . Each tooth/root was analyzed according to 3 indices of periradicular status at 2 time points . The main outcome measure was the presence of apical periodontitis . The criteria used for evaluation of the outcome were modified from Strindberg . Data were subjected to univariate and multivariate analysis . Logistic regression models were fit by using various clinical measures to determine which combination of biologic and treatment-associated factors best predicted treatment outcome . RESULTS The preoperative pulp diagnosis , the periapical diagnosis , the preoperative periapical radiolucency size , and the sex of the patients were revealed , by means of univariate analysis , to exert a significant influence on endodontic treatment outcome ( P < .05 ) . In the logistic regression model , the strongest effect on postoperative healing was the presence and magnitude of preoperative apical periodontitis . In the presence of this variable , no other factor contributed value to the prediction . The correct prediction of this model was 74.7 % ( P < .05 ) . CONCLUSION The major biologic factors influencing the outcome of endodontic treatment appear to be the extent of microbiological insult to the pulp and periapical tissue , as reflected by the periapical diagnosis and the magnitude of periapical pathosis The root canals of 588 consecutive nonsurgical patients with varying levels of pain were completely instrumented in 10 endodontic practice s and 4 endodontic graduate programs . The participants were sequentially assigned to one of nine medications and a placebo . The severity of pain was assessed by the visual analog scale for 72 h following instrumentation . Among all of the parameters studied , three factors ( preoperative pain , apprehension , and types of medication ) were found to be significant in determining postinstrumentation pain . An association was found between the intensity of pre- and postoperative pain . As the intensity of preoperative pain increased , the chances for more severe postoperative pain increased ( p < 0.0001 ) . In addition , an association between the presence of apprehension before any treatment and postoperative pain was also noted ( between 0.012 < p < 0.047 ) . Examination of the time-effect curves for various medications in patients with no mild pain showed no statistical significant difference between the effectiveness of different medications and placebo . However , a multiple comparison of the effectiveness of various medications and placebo on patients in moderate and severe preoperative pain showed that  ibuprofen , ketoprofen , erythromycin base , penicillin , and methylprednisolone plus penicillin  were more effective than placebo within the first 48 h following complete instrumentation This prospect i ve study review s the early outcomes of 223 consecutive Brånemark implants placed in 78 patients by one operator . Patients were divided into three groups : nonsmokers ( NS ) ; smokers who followed a smoking cessation protocol ( SQ ) ; and smokers who continued to smoke ( SNQ ) . There was a statistically significant difference between failure rates in the NS and SNQ groups ( P < .005 ) and between the SQ and SNQ groups ( P < .05 ) , but none between the NS and SQ groups . It is concluded that the smoking cessation protocol described shows considerable promise in improving success rates for osseointegration in smokers who follow it STATEMENT OF PROBLEM The in vitro effectiveness of a uniform circumferential ferrule has been established in the literature ; however , the effect of a nonuniform circumferential ferrule height on fracture resistance is unknown . PURPOSE This in vitro study investigated the resistance to static loading of endodontically treated teeth with uniform and nonuniform ferrule configurations . MATERIAL AND METHODS Fifty extracted intact maxillary human central incisors were r and omly assigned to 1 of 5 groups : CRN , no root canal treatment ( RCT ) , restored with a crown ; RCT /CRN , no dowel/core , restored with a crown ; 2 FRL , 2-mm ferrule , cast dowel/core and crown ; 0.5/2 FRL , nonuniform ferrule ( 2 mm buccal and lingual , 0.5 mm proximal ) , cast dowel/core and crown ; and 0 FRL , no ferrule , cast dowel/core and crown . The teeth were prepared to st and ardized specifications and stored for 72 hours in 100 % humidity prior to testing . Testing was conducted with a universal testing machine with the application of a static load , and the load ( N ) at failure was recorded . Statistical analysis was performed with a 1-way analysis of variance and the Tukey Honestly Significant Difference test ( alpha=.05 ) . The mode of fracture was noted by visual inspection for all specimens . RESULTS There was strong evidence of group differences in mean fracture strength ( P < .0001 ) . Following adjustment for all pairwise group comparisons , it was found that the lack of a ferrule result ed in a significantly lower mean fracture strength ( 0 FRL : 264.93 + /- 78.33 N ) relative to all other groups . The presence of a nonuniform ( 0.5 to 2-mm vertical height ) ferrule ( 0.5/2 FRL : 426.64 + /- 88.33 N ) result ed in a significant decrease ( P = .0001 ) in mean fracture strength when compared with the uniform 2-mm vertical ferrule ( 2 FRL : 587.23 + /- 110.25 N ) , the group without RCT ( CRN : 583.67 + /- 86.09 N ) , and the RCT -treated tooth with a crown alone ( CRN/ RCT : 571.04 + /- 154.86 N ) . The predominant mode of failure was an oblique fracture extending from the lingual margin to the facial surface just below the insertion of the tooth into the acrylic resin . 
    Output:
    
On the basis of survival rates , it appears that more than 95 percent of dental implants and teeth that have undergone endodontic treatment remain functional over time .
The result should be high levels of comfort , function , longevity and esthetics for patients