***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: Abstract Objective To compare a  four‐ and six‐implant maxillary overdenture  after an observation period of 5 years . Material and methods Fifty subjects with functional problems concerning their maxillary denture , who had ample bone volume in the anterior region to place four or six implants , were included and r and omly assigned to either group . Implant and overdenture survival , clinical performance , marginal bone loss and patient satisfaction were assessed . Results Forty‐six patients completed the 5‐year follow‐up . One implant failed in the six implants group ( 99.2 % survival ) and none in the four implants group ( 100 % survival ) . No overdentures had to be replaced during the observation period and the number of complications was limited . Clinical function was good , with no difference in clinical parameters between the groups . Mean marginal bone resorption was 0.50 ± 0.37 and 0.52 ± 0.43 mm in the four and six implant group respectively . Conclusion In patients with functional complaints of their maxillary denture , bar‐supported overdentures on four implants in the anterior maxillary region were not inferior to overdentures supported by six implants after 5 years of function . Implant survival and patient satisfaction were high , clinical parameters favourable , bone loss and complications to the denture were minor in both groups ( Clinical trial registration number : NTR2969 ) OBJECTIVE Comparing treatment outcome of four and six bar-connected implants in the anterior maxillary region to support an overdenture during a 1-year follow-up period . MATERIAL AND METHODS Fifty edentulous patients with lack of retention and stability of the upper denture , but with sufficient bone volume to place implants in the anterior maxillary region , were selected . R and omization assigned patients to either four or six implants .  Implant survival , overdenture survival , clinical scores , radiographic bone height changes , and patients ' satisfaction were assessed . RESULTS Forty-nine patients ( one drop out ) completed the 1-year follow-up . After 1 year , implant survival was 100 % in the four implants group and 99.3 % in the six implants group ( one implant lost ) . Overdenture survival was 100 % in both groups . Mean clinical scores were low and did not differ between groups ( independent Student 's t-test ) . Mean marginal bone resorption was 0.24 ± 0.32 mm in the four implants group and 0.25 ± 0.29 mm in the six implants group . Patients ' satisfaction had improved in both groups ( paired Student 's t-test ) . CONCLUSION Bar-supported overdentures on four implants in the anterior maxillary region are not inferior to overdentures supported by six bar-connected implants . Implant survival was high , peri-implant conditions were healthy and patients ' satisfaction had increased significantly in both groups PURPOSE To analyze maintenance service of fixed maxillary prostheses and overdentures based on conventional gold bars or titanium bars and frameworks fabricated with computer-aided design /computer-assisted manufacture ( CAD/CAM ) technology . MATERIAL S AND METHODS Forty-one patients participated ; 16 received an implant overdenture with a gold bar ( gold OD ) , 12 received a CAD/CAM-fabricated implant OD with a titanium bar ( Ti OD ) , and 13 received a  CAD/CAM implant-supported fixed prosthesis ( IFP ) . The bars and frameworks were screw-retained at the implant level . Maintenance service performed during the first 2 years was recorded and compared between the three groups . After this 2-year period , the Oral Health Impact Profile ( OHIP ) was administered . RESULTS For ODs ( gold , Ti ) most service consisted of activation of the matrices . Fractures of matrices and bar extensions occurred only in the gold OD group , and 65 % of these patients exhibited hyperplasia of the peri-implant mucosa . The maintenance rates were 1.24 ( gold OD ) , 1.36 ( Ti OD ) , and 0.98 ( IFP ) . These differences were not statistically significant . Retightening of occlusal screws was not necessary in any group . The probability that a complication occurred in the first year was high ( 60 % to 70 % ) and statistically not different between the three groups . The probability that a second complication occurred was significantly lower for the IFP group versus the gold OD group . The mean OHIP values were 1.7 ( IFP ) , 6.7 ( gold OD ) , and 7.3 ( Ti OD ) ; ratings in the IFP group were significantly better . CONCLUSIONS Maintenance service was typical for implant prostheses in the edentulous maxilla . Direct screw retention at the implant level without abutments had a favorable effect in all groups . A trend toward a reduction in problems was observed with the CAD/CAM superstructures . The OHIP confirmed high satisfaction , but quality of life appeared to be slightly higher with fixed prostheses In this prospect i ve multicenter study , non-submerged ITI implants were followed in order to evaluate their long-term prognosis in fully edentulous jaws . A total of 1286 implants were inserted in 233 consecutive patients and , after a healing period of three to six months , the successfully integrated implants were restored with 163 overdentures and 95 fixed full-arch bridges . This prospect i ve study not only calculated the 10-year cumulative survival and success rates for the 1286 implants by life table analysis , but also evaluated the actual survival and success rates for 498 implants after at least five years of functional loading . In addition , cumulative success rates were calculated for implant subgroups according to implant length and location . Additional analyses were performed to evaluate the estimated and actual survival and success rates of the implants in relation to various prosthetic rehabilitation techniques . The 10-year cumulative survival and success rates were 95.9 % and 92.7 % , respectively . The actual 5-year survival and success rates of the first 498 implants that were inserted were 97.7 % and 95.0 % , respectively . The analysis of implant subgroups showed slightly more favourable cumulative success rates for 12 mm long implants ( 93 % ) , in comparison to 10 mm and 8 mm long implants ( 91.6 % and 89.6 % , respectively ) . The cumulative success rate for m and ibular implants ( approximately 94 % ) was also more favourable than that for maxillary implants ( approximately 91 % ) . Patients who were loaded with both maxillary and m and ibular prostheses maintained success rates well above 90 % ; while only implants that were inserted to support maxillary overdentures that were retained by Dolder bars showed a success rate below 90 % OBJECTIVE To compare the treatment outcome of 4 vs. 6 bar-connected implants in the posterior region of the maxilla to support an overdenture during a 1-year follow-up period . MATERIAL S AND METHODS Sixty-six edentulous patients with an insufficient amount of bone volume in the maxilla to place implants were asked to participate in this study . R and omization assigned patients to either 4 or 6 implants . In all patients , a maxillary sinus floor elevation procedure with bone from the iliac crest was performed , and after a 3-month healing period , 4 or 6 dental implants were inserted in the maxillary posterior region in a one-stage procedure . After 3 months of osseointegration , a bar-supported overdenture was constructed . Implant survival , overdenture survival , clinical scores , peri-implant bone height changes and patients ' satisfaction were assessed . Study analysis was performed according a non-inferiority design . RESULTS All patients completed the one-year follow-up . After a functional period of 1-year , implant survival was 100 % in the 4 implants group and 99.5 % in the 6 implants group . Overdenture survival was 100 % in both groups . Mean clinical scores were very low and did not significantly differ between groups . Mean marginal bone resorption was 0.35 ± 0.31 mm and 0.46 ± 0.34 mm in the 4 and 6 implants group , respectively . Patients ' satisfaction improved significantly in both groups , but did not differ between groups . CONCLUSION A bar-supported overdenture on 4 implants in the posterior maxillary region is not inferior to an overdenture supported by 6 bar-connected dental implants PURPOSE To evaluate patient-related outcomes in restoring the edentulous maxilla with an implant overdenture . MATERIAL S AND METHODS A comprehensive systematic review of the literature was conducted . Publications reporting patient-based outcomes with concomitant data on implant and /or prosthetic success were selected using predetermined inclusion criteria that were agreed upon by the two review ers . RESULTS Twenty-three publications related to 20 study cohorts were identified to meet the inclusion criteria for maxillary implant overdentures : two r and omized controlled trials ( RCTs ) , 13 prospect i ve case series including two crossover trials , and five retrospective studies . CONCLUSION An implant overdenture offers a stabilized removable solution for the edentulous maxilla , which provides increased patient satisfaction and quality of life improvement . A palateless design supported by four to six implants with a wide anteroposterior span has been successfully applied in some investigations . A higher failure rate was experienced with machined implants , particularly with short implants ( length < 10 mm ) . Although both splinted and solitary anchorage systems are advocated , maintenance is higher for solitary attachments and inflammation is increased beneath the bars . Long-term maintenance care is essential for all design s. Well- design ed RCTs with larger sample cohorts with longer follow-up periods are required to amplify patient- and clinician-based outcomes Although maxillary implant overdentures are used in oral rehabilitation , different design s have not been compared previously in clinical trials . This crossover trial was design ed to measure differences in patient satisfaction with maxillary long-bar implant overdentures with and without palatal coverage opposed by a fixed m and ibular implant-supported prosthesis . Data were also gathered on new conventional dentures and on maxillary conventional dentures opposed by m and ibular fixed prostheses .  Sixteen participants were selected from a population wearing conventional dentures . Fifteen received new upper and lower dentures  ( 1 drop-out ) . Four implants were placed in the maxilla and m and ible ( 2 drop-outs ) . A m and ibular fixed prosthesis was inserted in 13 participants , who were then divided into 2 groups . One group ( n = 7 ) received long-bar overdentures with palate , then long-bar overdentures without palate . The other group ( n = 6 ) received the same treatments in the reverse order . Mastication tests and psychometric evaluations using Visual Analog Scales and Categorical Scales were performed throughout the study . General satisfaction was very high with both maxillary implant-supported prostheses , as were ratings of almost all psychosocial and functional variables . There were no significant differences between treatments , suggesting that patients are equally satisfied with long-bar overdentures with and without palate when these are opposed by m and ibular fixed prostheses . However , the ratings given to the maxillary implant prostheses were not significantly higher than for new conventional maxillary prostheses . This suggests that maxillary implant prostheses should not be considered as a general treatment of choice in patients with good bony support for maxillary conventional prostheses PURPOSE To evaluate telescopic crown ( TC ) , bar , and locator attachments used in removable four implant-supported overdentures for patients with edentulous maxillae . MATERIAL S AND METHODS A total of 30 maxillary edentulous patients were enrolled in a 3-year prospect i ve study . Ten patients ( group A ) were treated with overdentures supported by TCs , 10 patients ( group B ) with overdentures supported by bar attachments , and 10 patients ( group C ) with overdentures supported by locator attachments . A total of 120 implants were used to restore oral function . During the 3-year follow-up period , implant survival and success rates , biologic and mechanical complications , prosthodontic maintenance efforts , and patient satisfaction were evaluated . RESULTS All 30 patients were available for the 3-year follow-up and exhibited 100 % implant survival and success rates . Peri-implant marginal bone resorption was not statistically significant for the three groups . There were lower plaque , bleeding , gingiva , and calculus indices in group C compared with groups A and B. The number of prosthodontic maintenance visits revealed eight complications in the TC group , seven complications in the bar group , and four complications in the locator group . However , there were no differences in the clinical effects of the overdentures in the three groups . CONCLUSION Within the limits of this prospect i ve study , it was concluded that the locator system produced superior clinical results compared with the TC and bar attachments in terms of peri-implant hygiene parameters , the frequency of prosthodontic maintenance measures , cost , and ease of denture preparation . However , longer-term prospect i ve studies are required to confirm these results 
    Output:
    
CONCLUSION Within the limits of this systematic review , it can be concluded that the survival rates of implants and overdentures and patient satisfaction with a maxillary overdenture supported by four implants were not influenced by the overdenture design , and no statistical difference was detected between the splinted and unsplinted groups