***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: BACKGROUND The aim of the present study was to compare the peri-implant soft tissue health status of implants supporting overdentures with bar attachments or ball attachments in the m and ible , as well as patient satisfaction with these attachment types . METHODS The study included a Dolder bar group with 18 cases ( 43 implants ) and a ball attachment group with 18 cases ( 51 implants ) . The mean function period in the Dolder bar group was 49 months ( range : 12 to 72 months ) and in the ball attachment group , the mean was 23 months ( range : 12 to 40 months ) . Implants were clinical ly evaluated by using a modified plaque index ( mPI ) , modified sulcus bleeding index ( mSBI ) , and probing depths . Patient satisfaction with the treatment was recorded using a question naire . RESULTS mPI , probing depth , and mSBI did not statistically differ between groups ( Mann-Whitney U test , P > 0.05 ) . Patient satisfaction was similar with both retentive systems . CONCLUSION Within the limits of this study , we concluded that there was no significant difference between the 2 attachment types used for implant-supported overdentures with respect to the soft tissue health status or patient satisfaction In earlier studies of Astra Tech and Brånemark System implants , high survival rates and small marginal bone changes have been demonstrated . The aim of this study was to compare the two systems , primarily with regard to marginal bone changes , but also with regard to other clinical variables of interest . The present paper describes the results after three years . Sixty-six patients were included in the study and r and omly assigned to treatment with Astra Tech implants ( n = 184 ) or Brånemark System implants ( n=187 ) . The marginal bone level was radiographically examined at fixture insertion , at abutment connection , at baseline ( delivery of the prosthetic construction ) and at 1- and 3-year follow-up examinations . Between fixture insertion and the baseline examination , the pattern of marginal bone resorption differed between the two systems . However , there was no significant marginal bone change between baseline and the 1-year examination or between the 1- and 3-year examinations . Nor were there any differences between the systems . The mean bone loss in the upper jaw between BL ( baseline ) and 3 years was 0.2 + /- 0.3 mm for Astra Tech implants and 0.2 + /- 0.1 mm for Brånemark System implants . The corresponding figures for the lower jaw were 0.3 + /- 0.2 mm and 0.2 + /- 0.1 mm . The survival rate of Astra Tech implants was significantly higher ( 98.9 % ) than for Brånemark System implants ( 95.2 % ) . However , five of the nine implant losses in the Brånemark group occurred in one patient . For that reason , this result must be interpreted with caution . The number of patients with implant losses did not differ significantly between the systems . Few complications were recorded up to 3 years Recent empirical evidence supports the importance of adequate r and omization in controlled trials . Trials with inadequate allocation concealment have been associated with larger treatment effects compared with trials in which authors reported adequate allocation concealment . While that provides empirical evidence of bias being interjected into trials , trial investigators rarely document the sensitive details of subverting the intended purpose of r and omization . This article relates anonymous accounts run the gamut from simple to intricate operations , from transillumination of envelopes to search ing for code in the office files of the principal investigator . They indicate that deciphering is something more frequent than a rate occurrence . These accounts prompt some method ological recommendations to help prevent deciphering . R and omized controlled trials appear to annoy human nature -- if properly conducted , indeed they should BACKGROUND Oral implant treatment ad modum Brånemark has been used for decades in the rehabilitation of edentate and partially dentate patients . Posterior jaw regions frequently exhibit bone of poor texture , and it is often difficult to obtain primary stability . Thus , it may prove beneficial to deviate from the original protocol and to use implants with a modified design , for example , with a slightly tapered geometry . PURPOSE The purpose of the investigation was to compare the early behavior of a modified ( prototype Mk IV , Brånemark System , Nobel Biocare AB , Gothenburg , Sweden ; test ) implant with that of the st and ard Brånemark implant ( control ) in regions of mainly type 4 bone . MATERIAL S AND METHODS Three Swedish centers participated , and a total of 44 patients were treated with oral implants for 39 maxillas and 5 m and ibles . The study focused on the most distal right and left implant sites ( 88 implants ) , which were r and omized to receive either a test or a control implant . Various parameters were recorded , such as registered insertion torque ( OsseoCare ) , Nobel Biocare AB ) , wobbling during insertion , primary and secondary stability ( as measured with resonance frequency ) , and marginal bone loss . The implants were followed up for 1 year . RESULTS The test implant more frequently required a higher insertion torque and showed a significantly higher primary stability than the control implant . This difference in stability leveled out over time , and test and control implants exhibited similar secondary stability at abutment operation and at the 1-year visit . Wobbling during insertion was rarely recorded for either of the implant design s. The 1-year cumulative success rate was 93.1 % for test implants and 88.4 % for control implants . CONCLUSIONS The modified implant design result ed in an increased primary stability , which may be important when placing implants in jaw regions of type 4 bone . However , independent of the achieved primary stability , successful implants tended to approach similar secondary stability in the two design s tested This paper describes the 5-year results of a comparative study between Astra Tech and Brånemark system implants . The aim was to compare the systems primarily with regard to bone level changes , and also with regard to other variables of interest . Sixty-six patients with edentulous jaws were included in the study . R and omisation schedules were used to allocate the patients to the two implant systems . 184 Astra Tech implants with a titanium-blasted surface and 187 Brånemark implants with a turned surface were used . The implants were inserted with a two-stage technique and the insertion followed the routines for the respective implant system . All patients were provided with full-arch fixed bridges . All patients were followed up with clinical and radiographic examinations from fixture insertion to the 5-year follow-up . The total mean bone level change in the upper jaw between fixture insertion and the 5-year examination was -1.74+/-0.45 mm at the Astra implants and -1.98+/-0.21 at the Brånemark implants . The corresponding values for the lower jaw were -1.06+/-0.19 for Astra and -1.38+/-0.17 for Brånemark . The major postoperative changes of the marginal bone level took place between fixture insertion and baseline . During this period , there was also a different pattern of bone remodelling between the implant systems . Between baseline ( prosthesis connection ) and the 5-year examination , the marginal bone level changes were small , with no difference between the implant systems . The implant stability was examined with the supraconstructions removed . At the 5-year examination , the survival rate for Astra Tech implants was 98.4 % and for the Brånemark implants it was 94.6 % . The difference was not statistically significant In a multicenter clinical trial treatment , the effects of overdentures on different implant systems in patients with severely resorbed m and ibles were compared 1 year after the insertion of new dentures . The implant systems used were the transm and ibular implant ( TMI ) , the IMZ ( IMZ ) , and the Brånemark system ( BRA ) . Treatment was r and omly assigned to 88 patients according to a balanced allocation method . Evaluation included peri-implant and radiographic parameters . According to the Delphi method a Clinical Implant Performance scale ( CIP ) was constructed based on all conceivable complications of the different implant systems . During the healing period , one IMZ and one BRA implant were lost , and one TMI implant was removed after functional loading . The results of the peri-implant and radiographic parameters and the CIP scale revealed no significant differences between the three implant systems STATEMENT OF PROBLEM Treatment of tooth loss in the anterior maxilla can involve difficult functional , esthetic , and psychologic problems , especially in young patients with otherwise good dentition . PURPOSE The purpose of this study was to provide a preliminary comparative evaluation of two implants ( ITI and Astra ) in single-tooth restorations . MATERIAL AND METHODS This prospect i ve study of 102 single-tooth replacements with 56 ITI and 46 Astra dental implants was performed in 82 patients at the Finnish Student Health Service Foundation . One Astra implant was lost before loading . The overall survival rate of the implants was 97.8 % for Astra implants and 100 % for the ITI system . After the initial healing period of at least 6 months , the remaining 101 implants ( 56 ITI , 45 Astra ) were free of periimplant infection and revealed no detectable mobility . Radiographs did not reveal signs of periimplant radiolucencies . All 101 implants received single-tooth crowns . RESULTS Periimplant parameters and acceptable implant function were examined and demonstrated satisfactory results with preestablished clinical parameters and radiographs at 1 year . During the observation time the mean marginal bone loss was 0.13 mm with Astra implants and 0.11 mm with ITI implants . Subjectively all patients were satisfied with their single-tooth restorations supported by either ITI or Astra dental implants . CONCLUSION The favorable results of this short-term study support the application of the two implant systems for single-tooth restorations , especially in the anterior region of the maxilla BACKGROUND Maintenance of the health and integrity of the bone-implant complex ( osseointegration ) has been shown to be essential for long term success of root-form , endosseous dental implants .  If reliable clinical indicators of adequacy of the bone-implant complex existed , they could stimulate new and innovative early intervention research to arrest of reverse early deterioration of the bone-implant complex . In the absence of such indicators , this has been problematic . The Periotest may have the potential to provide this information by indirectly assessing the status of the bone-implant complex . However , little information is available that documents either the capability of the Periotest to reliably assess changes of the bone-implant complex or the " normal variations " in Periotest values ( PTVs ) for both HA-coated and non-coated implants . METHODS The purpose of this paper was to document changes in PTVs as influenced by various implant surfaces , implant design s , and bone densities . The mean PTVs recorded for each visit , for all implant types and bone densities , were combined to provide an overall average PTV ( A-PTV ) . The changes in stability ( PTVs ) were analyzed using a generalized linear model ( GLM ) with repeated measures ( Hotelling 's Trace ) . RESULTS The A-PTV for all implants over all visits was -3.5 . The mean PTVs ranged from -4.2 ( SD = 2.4 ) at uncovering to -3.9 ( SD = 2.9 ) at 60 months . All implants in bone qualities 1 and 2 ( BQ-1 and BQ-2 ) became more stable over time , while those in bone quality 3 or 4 ( BQ-3 and BQ-4 ) showed a slight decrease in stability . In BQ-1 , the mean PTVs increased from -4.7 at uncovering to -4.9 at 60 months . A similar increase in stability occurred in BQ-2 ( -4.1 at uncovering to -4.4 at 60 months ) . In BQ-3 , the stability of the implants decreased over time ( -3.6 at uncovering to -2.9 at 60 months ) , with similar changes recorded for BQ-4 ( -2.5 at uncovering to -1.0 at 60 months ) . When comparing the stability of all HA-coated with all non-coated implants , the HA implants became less stable ( -4.4 to -3.4 ) over time , while non-coated implants showed an improvement in stability ( -3.5 to -4.5 ) . The changes in stability found in BQ-1 , BQ-2 , and BQ-3 were similar , with HA implants becoming less stable and non-coated more stable . HA- and non-coated comparisons were not possible in BQ-4 since there were too few non-coated implants placed in this type of bone . The HA-coated screw showed a decrease in stability when compared to the non-coated screw . CONCLUSIONS Conclusions of the study are as follows : 1 ) PTVs are influenced by bone quality and surface coating of the implant ; 2 ) the PTVs at the time of uncovering provide the best estimate of a clinical ly acceptable PTV for that bone-implant complex ; 3 ) while the PTVs for any bone-implant complex may fluctuate + /- 1.0 around the uncovering PTV during routine healing and loading of the implant , a consistent shift toward a positive PTV that approaches " 0 " should be cause for concern that the bone-implant complex may be at risk of failure ; 4 ) HA-coated implants became slightly less stable ( more positive PTVs ) over time , while the non-coated implants became more stable ( more negative PTVs ) ; and 5 ) until a " critical PTV " can be accurately identified , it is suggested that a consistent shift in recorded PTVs that exceeds the + 3.0 value on the PTV scale should be viewed with concern for possible deterioration at the bone-implant complex S and blasted and acid-etch 
    Output:
    
On a patient rather than per implant basis there were no statistically significant differences for failures , marginal bone level changes on intraoral radiographs and peri-implantitis between various implant systems .
REVIEW ER 'S CONCLUSIONS There was no evidence that any of the implant systems evaluated was superior to the other .