***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: OBJECTIVE The purpose of this prospect i ve clinical study was to evaluate peri-implant soft-tissue conditions and esthetic fulfillment during a 3-year follow-up period following prosthetic rehabilitation . MATERIAL AND METHODS As part of a prospect i ve multi-center study , 152 ITI dental implants were placed in 80 patients in the maxillary anterior region . Fifty-nine crowns ( 38.82 % ) were cement retained , while 93 ( 61.18 % ) crowns were screw retained . At loading and 3 , 6 , 12 and 36 months post-loading , modified plaque index ( MPI ) , sulcus bleeding index ( SBI ) , keratinized mucosa ( KM ) , gingival level ( GL ) , and esthetic fulfillment were recorded . RESULTS All patients completed the study and no complications were reported . While statistically not significant at all time points , cement-retained crowns seemed to present a worsening trend in MPI and SBI scores . Interestingly , screw-retained crowns seemed to present an opposite picture , their MPI and SBI scores improved over time . While plaque accumulation , prophylaxis and depth of crown margin significantly affected levels of sulcus bleeding , prophylaxis alone played a key role in reducing plaque accumulation . No soft tissue recession was observed in either cement- or screw-retained crowns up to 3 years post-loading . Esthetic fulfillment survey revealed that patients did not have a preference for crown types ; however , dentists favored cement-retained over screw-retained crowns . CONCLUSIONS Peri-implant soft tissues responded more favorably to screw-retained crowns when compared with cement-retained crowns . However , no soft-tissue recession was observed in either type of crowns . Cement-retained crowns were preferred by dentists , while patients were equally satisfied with either type of crowns they received STATEMENT OF PROBLEM There is a widespread belief that maxillary overdenture prostheses are associated with a higher frequency of complications and require more maintenance than fixed implant prostheses . PURPOSE This prospect i ve clinical study compared the treatment outcomes of fixed and removable implant-supported restorations in the edentulous maxilla with the main emphasis on the clinician 's point of view . MATERIAL AND METHODS Ten patients were treated with fixed screw-retained implant prostheses ( group 1 ) , and 10 patients were treated with removable implant-supported overdentures ( group 2 ) in the edentulous maxilla . Recall was scheduled at 6-month intervals to investigate the prosthodontic treatment outcomes , including implant survival , prosthesis time until retreatment , and maintenance issues . Clinical parameters gingival index ( GI ) , plaque index ( PI ) , the clinical attachment level , and radiographic marginal bone levels measured , along with any biologic and mechanical complications were recorded . RESULTS Patients were followed over a mean period of 39 months ( SD=7 ; group 1 ) and 27 months ( SD=10 ; group 2 ) after implant placement . Cumulative implant survival was 97.6 % for group 1 and 94.4 % for group 2 after an 18-month observation period . The mean time until retreatment after prostheses insertion was 23.4 months for group 1 and 19.8 months for group 2 ( n.s . ) . In both groups , the increase over time in the radiographically investigated bone level was found to be significant . The indices given for the mucosal health and oral hygiene status ( GI and PI ) were highly correlated in both groups at each recall appointment , but no significant differences were found between groups 1 and 2 . CONCLUSION In groups 1 and 2 , comparable prosthodontic treatment outcomes were achieved . The majority of mechanical complications could be managed chairside during recall visits and did not require additional appointments , so that the time and costs involved in providing maintenance were kept down In this multicenter prospect i ve study , the results achieved with the use of Brånemark implants for single tooth replacement were evaluated . The overall cumulative success rate was 95.9 % for implants and 91.1 % for crowns . Two of the 99 implants placed had to be removed before the prosthodontic stage of treatment ; thus , 97 were restored with CeraOne crowns . Seventy-seven implants were evaluated radiographically at the 1-year follow-up , 57 at 3 years , and 47 at 5 years . Mean marginal bone resorption was well within the limits set by Albrektsson et al in 1986 . The status of the soft tissue around crowns and adjacent teeth remained stable over the evaluation period . The gold abutment screw in the CeraOne system seems to have eliminated the problem of loosening abutment screws in single tooth replacements . The results suggest that the Brånemark system can be safely used for tissue-integrated replacement of single teeth PURPOSE To evaluate the predictability of Straumann wide-neck dental implants ( 6.5-mm prosthetic neck with a 4.8-mm endosseous s and blasted , large-grit , acid-etched-surface body ) used for molar replacement . MATERIAL S AND METHODS Four hundred ninety-nine single-tooth implants were restored in molar sites in 410 patients ( mean time of loading 23 months ; range , 1 to 54 months ) by 6 clinicians throughout the United States . Three hundred-fifty nine implants  were placed in the m and ible and 148 implants in the maxilla . RESULTS The overall cumulative survival rate was 98.4 % for all sites ( 8 failures ) . Survival rates of 99.2 % for m and ibular molars ( 3 failures ) and 96.6 % for maxillary molars ( 5 failures ) were achieved . Survival rate of implants  placed in conjunction with the bone-added osteotome procedure in the maxillary molars was 89 % , with 5 of 45 procedures leading to failure . DISCUSSION Minimal restorative problems were encountered . No cases of abutment loosening or fractures were observed for cemented restorations on solid abutments . CONCLUSION The data suggest that the Straumann solid-screw , wide-neck implants can be a satisfactory choice for molar single-tooth replacement PURPOSE The purpose of this prospect i ve multicenter study was to evaluate and compare the clinical performance of laser-welded titanium fixed partial implant-supported prostheses with conventional cast frameworks . MATERIAL S AND METHODS Forty-two partially edentulous patients were provided with Brånemark system implants  and arranged into 2 groups . Group A was provided with a conventional cast framework with porcelain veneers in one side of the jaw and a laser-welded titanium framework with low-fusing porcelain on the other side . The patients in group B had an old implant prosthesis replaced by a titanium framework prosthesis . The patients were followed for 3 years after prosthesis placement . Clinical and radiographic data were collected and analyzed . RESULTS Only one implant was lost , and all prostheses were still in function after 3 years . The 2 framework design s showed similar clinical performance with few clinical complications . Only one abutment screw ( 1 % ) and 9 porcelain tooth units ( 5 % ) fractured . Four prostheses experienced loose gold screws ( 6 % ) . In group A , marginal bone loss was similar for both design s of prostheses , with a mean of 1.0 mm and 0.3 mm in the maxilla and m and ible , respectively . No bone loss was observed on average in group B. No significant relationship ( P > 0.05 ) was observed between marginal bone loss and placement of prosthesis margin or prosthesis design . CONCLUSION The use of laser-welded titanium frameworks seems to present similar clinical performance to conventional cast frameworks in partial implant situations after 3 years OBJECTIVES The aim of the present study was to compare the delayed-immediate ( I m ) and the delayed ( De ) protocol s for placement of single-tooth implants . MATERIAL AND METHODS After allocation to the I m and De groups by r and om , 46 patients were treated with a single-tooth implant with acid etched surfaces ( Osseotite ) in the anterior or pre-molar region of the maxilla or the m and ible on average 10 days ( I m ) or 3 months ( De ) following tooth extraction , respectively . Forty-one patients attended a follow-up visit 2 years after implant placement corresponding to 1(1/2 ) years of loading of the implant restorations . Peri-implant and prosthetic parameters were evaluated clinical ly and marginal bone levels measured on radiographs . RESULTS Three implants were lost , all before mounting of the crown . None of the implant restorations had failed after 1(1/2 ) years of function . Probing pocket depths were reduced by up to 1.4 mm on average from the time of loading to the 2-year follow-up and at that time , no significant difference between the I m and De groups was found ( 4.2 versus 4.1 mm ) . A statistically significant radiographic marginal bone loss had occurred in the I m group ( mean=0.8 mm ) as well as in the De group ( mean=0.7 mm ) in the follow-up period . However , a mean marginal bone level of approx . 1.5 mm in both groups measured from the implant-abutment junction was found to be acceptable . It was demonstrated that probing pocket depths and marginal bone levels after 1(1/2 ) years of loading of the implant-retained crowns were not influenced by the presence of peri-implant bone defects immediately after implant placement . Furthermore , no severe prosthodontic complications , such as screw loosening or porcelain fractures , arose in this study material . CONCLUSION High success rates of single-tooth implants after 1(1/2 ) years of function were achieved using the delayed-immediate and delayed implant placement techniques This report involves the retrospective evaluation of  ITI implants placed by a group of 12 clinicians located throughout the United States . Of the original 174 single implants placed in 129 patients reported previously , 157 were examined in 110 patients after 2 or more years ( average 40.1 months ) . Twenty-two implants remained in the anterior and 135 implants ( 86 % ) remained in the posterior areas of the mouth , with 81 being restored with an octabutment screw-retained crown and 76 restored with a conical-abutment cemented crown ( in function 2 years or longer ) . Occlusal screw loosening was observed in 22.2 % of implants over both periods , with only 1 tooth loosening in both study periods ( 6 months to 2 years and > or = 2 years ) . Loosening of a solid conical abutment occurred in 1 additional patient , for cumulative conical abutment loosening of 5.3 % . Significant radiographic bone loss was observed around 4 implants , with implant fracture noted with 3 additional implants ( all m and ibular first molars with hollow-screw or hollow-cylinder implant design ) . The survival rate at > or = 2 years was 95.5 % . The data suggest that ITI implants can be a satisfactory choice for posterior single-tooth restorations PURPOSE The purpose of this controlled prospect i ve clinical study was to compare cemented and screw-retained implant-supported single-tooth crowns followed for 4 years following prosthetic rehabilitation with respect to peri-implant marginal bone levels , peri-implant soft tissue parameters , and prosthetic complications . MATERIAL S AND METHODS Twelve consecutive patients were selected from a patient population attending the Implantology Department at the University of Padova . They all presented with single-tooth bilateral edentulous sites in the canine/premolar/molar region with adequate bone width , similar bone height at the implant sites , and an occlusal scheme that allowed for the establishment of identical occlusal cusp/fossa contacts . Each patient received 2 identical implants ( 1 in each edentulous site ) . One was r and omly selected to be restored with a cemented implant-supported single-tooth crown , and the other was restored with a screw-retained implant-supported single-tooth crown . Data on peri-implant marginal bone levels and on soft tissue parameters were collected 4 years after implant placement and analyzed to determine whether there was a significant difference with respect to the method of retention ( cemented versus screw-retained ) . RESULTS All patients completed the study . All 24 implants survived , result ing in a cumulative implant success rate of 100 % . Statistical analysis revealed no significant differences between the 2 groups with respect to peri-implant marginal bone levels and soft tissue parameters . DISCUSSION The data obtained with this study suggested that the choice of cementation versus screw retention for single-tooth implant restorations is likely not based on clinical results but seems to be based primarily on the clinician 's preference . CONCLUSIONS Within the limitations of this study , the results indicate that there was no evidence of different behavior of the peri-implant marginal bone and of the peri-implant soft tissue when cemented or screw-retained single-tooth implant restorations were provided for this patient population PURPOSE The present material reports on prosthodontic complications in a trial of 51 patients with prostheses supported by single-stage implants over a period of 36 months . MATERIAL S AND METHODS One hundred eighty-six single-stage implants were placed in 51 patients over a 3-year period in 2 carefully controlled prospect i ve clinical trials . Nineteen of the patients ( 103 implants ) were completely edentulous and restored with a maxillary complete denture and a m and ibular fixed-detachable complete prosthesis .  Single metal-ceram 
    Output:
    
There is no significant difference between cement- and screw-retained restorations for major and minor outcomes with regard to implant survival or crown loss .