***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 aim of the present prospect i ve clinical study was to compare patient-reported outcomes for maxillary conventional dentures and maxillary implant-supported dentures . MATERIAL AND METHODS Twenty-one patients ( 6 women and 15 men ) being edentulous in the maxilla and encountering problems with their existing dentures were included . Twelve patients ( 4 women and 8 men ) received a new set of conventional dentures , due to insufficient dentures . In nine patients ( 2 women and 7 men ) , the existing dentures were adjusted by means of relining or rebasing .  All patients received implant-supported dentures on two retentive anchors . In total , 42 implants were inserted in the anterior maxilla . The participants rated their satisfaction on their existing conventional dentures , 2 months after insertion of new conventional dentures and 2 months after insertion of implant-supported dentures . Thereby , patients responded to question naires capturing the oral health impact profile ( OHIP ) using visual analog scales . Seven domains ( functional limitation , physical pain , psychological discomfort , physical , psychological and social disability and h and icap ) were assessed . Higher scores implied poorer patient satisfaction . In addition , the question naire involved the evaluation of cleaning ability , general satisfaction , speech , comfort , esthetics , stability , and chewing ability . Higher scores implied higher patient satisfaction . RESULTS Patient satisfaction significantly increased for implant-supported dentures compared with old dentures in all seven OHIP subgroups , as well as for cleaning ability , general satisfaction , ability to speak , comfort , esthetics , and stability ( P < 0.05 ) . The comparison of new conventional dentures and implant-supported dentures revealed a statistically significantly increased satisfaction for functional limitation ( difference of 33.2 mm ) , psychological discomfort ( difference of 36.7 mm ) , physical disability ( difference of 36.3 mm ) , and social disability ( difference of 23.5 mm ) , ( P < 0.05 ) . Additionally , general satisfaction , chewing ability , speech , and stability significantly improved in implant-supported dentures ( P < 0.05 ) . CONCLUSIONS Within the limits of this study , maxillary dentures retained by two implants provided some significant short-term improvements over conventional dentures in oral- and health-related quality of life 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 BACKGROUND Patient-based outcomes with maxillary overdentures on a minimum number of implants , opposing m and ibular 2-implant overdentures are not evident in the literature . PURPOSE To evaluate patient 's satisfaction with maxillary 3-implant overdentures  , opposing m and ibular 2-implant overdentures , using two different attachment systems over the first 2 years of service . MATERIAL S AND METHODS Forty participants wearing m and ibular 2-implant overdentures for 3 years were r and omly allocated to one of two similar implant system groups to receive maxillary 3-implant overdentures . Twenty participants were allocated to splinted and unsplinted attachment system treatment groups for each system . Patient satisfaction with pre-treatment complete maxillary dentures , with maxillary 3-implant overdentures at baseline and annually for 2 years , was measured using visual analogue scale question naires and the oral health impact profiles . Palatal coverage of the maxillary overdentures was reduced at the first annual recall . RESULTS Data showed significant improvement in pain reduction , comfort , stability , and function variables of the visual analogue scale after treatment . Analysis by prosthodontic design using visual analogue scale showed no significant difference . The total oral health impact profile-14 scores after treatment for all participants , regardless of prosthodontic design , were significantly lower ( more satisfied ) . The overall oral health impact profile-20E score at baseline was significantly higher ( more satisfied ) compared with pre-treatment conventional maxillary dentures . No significant changes were observed in the first or second years compared with baseline results . Twenty-two participants ( 84.6 % ) preferred reduced palatal coverage , regardless of prosthodontic design , after 1 year . Twenty participants ( 76.9 % ) still preferred reduced palatal coverage at the end of the second year . CONCLUSIONS The provision of maxillary 3-implant overdentures to oppose m and ibular 2-implant overdentures significantly improve levels of patient satisfaction compared with conventional maxillary dentures STATEMENT OF PROBLEM The results of the  implant overdenture treatment in the maxilla remains inferior to those in the m and ible . Different reasons have been alluded to , such as bone quality and quantity , number of implants , as well as the prosthesis design . PURPOSE To investigate the latter , a new design for the rehabilitation of the resorbed maxillae was set up . MATERIAL AND METHODS Thirteen patients were selected and provided with four endosseous maxillary implants  , splinted with a rigid-cast bar . RESULTS After a mean loading time of 3 years , six implants were lost ; three at abutment and another three shortly after abutment connection , result ing in a cumulative success rate of 88.6 % at year 4 . A mean marginal bone loss of 0.3 mm was observed within the first year . After the first year , the marginal bone level , the attachment level , and the Periotest scores hardly changed . The main prosthetic complication was the frequent need to renew or to activate the attachments . A strong improvement in patient satisfaction was observed when compared with the old conventional denture . CONCLUSIONS Within the limits of this study , the outcome confirmed that , on a medium-term base , implant-retained hinging overdentures on four implants were promising Dental implants provide patients with restorative options for the edentulous maxilla . Both fixed and removable prostheses can be attached to the edentulous maxilla , but the efficacy of different design s has not been determined . In this two-session within-subject crossover trial we compared  maxillary implant retained fixed prostheses  with  removable implant overdentures  opposed by  m and ibular implant-supported overdentures .  Sixteen patients , who had previously received m and ibular implants , entered the study and received four to six maxillary implants .  After dropouts as a consequence of a lack of osseointegration and general health problems , 13 remained . Of these , five received the removable prosthesis first and eight the fixed prosthesis . After 2 months , the prostheses were exchanged and the second was also worn for 2 months . Psychometric measurements of general satisfaction with the prostheses as well as comfort , ability to speak , stability , esthetics , ease of cleaning and occlusion were obtained once each prosthesis had been worn for 2 months . Chewing ability was assessed for seven types of food . Removable long-bar overdentures received significantly higher ratings of general satisfaction than fixed prostheses ( P = 0.003 ) . Patients also rated their ability to speak and ease of cleaning significantly better with the removable overdentures . Nine patients chose to keep the removable prosthesis and four preferred to keep the fixed prosthesis . The results suggest that maxillary removable overdentures on multiple implants may provide patients with better function than fixed prostheses BACKGROUND For maxillary overdenture therapy , treatment guidelines are missing . There is a need for longitudinal studies . PURPOSE The purpose of this 1-year prospect i ve case series study was to assess the treatment outcome of maxillary overdentures supported by six dental implants opposed by natural antagonistic teeth in the m and ible . MATERIAL S AND METHODS Fifty patients were treated with a maxillary overdenture supported by six dental implants , either placed in the anterior region ( n = 25 patients ) or in the posterior region ( n = 25 patients ) . Items of evaluation were the following : survival of implants , condition of hard and soft peri-implant tissues , and patients ' satisfaction . RESULTS One-year implant survival rate was 98 % in the anterior group and 99.3 % in the posterior group . Mean radiographic bone loss in the anterior and posterior groups after 1 year of loading was 0.22 and 0.50 mm , respectively . Mean scores for plaque , calculus , gingiva , bleeding , and pocket probing depth were low , and patients ' satisfaction was high , with no differences between the groups . CONCLUSION Six dental implants placed in either the anterior region or the posterior region of the edentulous maxilla , connected with a bar , and opposed by antagonistic teeth in the m and ible supply a proper base for the support of an overdenture In 10 patients , 68 endosseous implants were inserted in the augmented edentulous maxilla using a one-stage implant placement technique . Three months before implant insertion , the width and height of the alveolar crest were augmented with autologous bone grafts from the iliac crest . In all cases , the result ing bone volume was sufficient for implant insertion . According to an early loading protocol , the implant-supported overdenture was fabricated 2 months after insertion of the implants . Evaluation was performed according to a st and ardised protocol immediately and 1 year after fabrication of the prosthetic construction . The protocol included assessment of both clinical ( bleeding score , pocket depth , implant mobility ) and radiographic ( marginal bone level on st and ardised radiographs ) parameters . Three implants in two patients in the upper jaw were lost ( survival rate : 95.6 % ) . The peri-implant tissues had a healthy appearance and bone loss was minimal . Overall , the patients were very satisfied with the prosthetic construction . From this preliminary study , it is concluded that in selected cases , early loading of implants may develop into a predictable treatment modality after augmentation of the maxilla 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 STATEMENT OF PROBLEM Distinct clinical parameters determine whether fixed or removable implant-supported prostheses are indicated to restore the edentulous maxilla . However , there is a strong belief that fixed implant prostheses meet with greater patient acceptance and satisfaction , but this may differ from the patients ' perceptions , their psychological responses to treatment , and their assessment s of the treatment outcome . 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 patient 's point of view . MATERIAL AND METHODS Twenty patients who requested an implant-supported superstructure to restore the edentulous maxilla were asked to complete a question naire measuring their satisfaction with the present situation and the psych 
    Output:
    
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 .