***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: 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 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 OBJECTIVE The purpose of this article was to present the preliminary results of a prospect i ve clinical trial comparing titanium plasma-sprayed versus hydroxyapatite-coated titanium plasma-sprayed cylinder ( press fit ) implants in different regions of the mouth . STUDY DESIGN Sixty-five subjects met the inclusion requirements . Surgery was done in two phases by four experienced surgeons . Implant placement and abutment connection were separated by 3 to 4 months in the m and ible , 6 to 7 months in the maxilla . Patients were assigned to either titanium plasma-sprayed or hydroxyapatite-coated implants on the day of surgery . Implant placement was not stratified for the region of the jaws . Outcome assessment was failure ( loss ) of an implant before or within 3 months of second phase surgery . RESULTS Three hundred fifty-two implants equally distributed between titanium plasma-sprayed and hydroxyapatite-coated titanium plasma-sprayed implants were placed in four different sites ; anterior maxilla , posterior maxilla , anterior m and ible , and posterior m and ible . There were a total of 15 failures ( 4.26 % ) . Overall , titanium plasma-sprayed implants showed a higher but not significant failure rate compared with hydroxyapatite-coated implants ( p = 0.06 ) . Although not statistically significant , we believe that a smoking history played an important role in the failure of implants . CONCLUSION This study suggests that an hydroxyapatite-coating of an implant allows superior initial integration when compared with a titanium plasma-sprayed surface BACKGROUND Step-wise reduction in loading protocol s is necessary to evaluate early loading of implants with m and ibular overdentures . PURPOSE To compare the success rates of two different dental implant systems following conventional or early loading protocol s in patients being rehabilitated with m and ibular overdentures . MATERIAL S AND METHODS Forty-eight edentulous participants were r and omly allocated to two different implant systems : one with a machined titanium implant surface ( Sterioss , Nobel Biocare , Yorba Linda , California , USA ) and the other with a roughened titanium surface ( Southern Implants , Irene , South Africa ) . For each system , the participants were further divided into control groups , in whom m and ibular implant overdentures and their respective matrices were inserted following a st and ard 12-week healing period , and test groups , in whom a 6-week healing period was followed prior to identical loading . Two unsplinted implants to support implant overdentures were placed in the anterior m and ible of all participants , using a st and ardized one-stage surgical procedure . Mobility tests and marginal bone levels , as well as peri-implant parameters , were evaluated at each baseline and 52 and 104 weeks after surgery . RESULTS There was no statistically significant difference in the success rates of the two systems in either control or test groups . At the 2-year evaluation , a success rate was found of 87.5 % and 70.8 % for the control and test Sterioss groups , respectively , and 83.3 % and 100 % for the control and test Southern Implants groups were observed . For the Sterioss groups , eight implants were lost at an early stage : seven in the test group and one in the control group . For the Southern Implants control and test groups , no failures were seen at any time interval . There were no significant differences in marginal bone loss , Periotest values , and peri-implant parameters between implant systems or between any of the control or test groups . CONCLUSIONS Early loading , with step-wise reductions in loading protocol s , of unsplinted machined Sterioss and roughened Southern Implants fixtures with m and ibular overdentures is possible for up to 2 years BACKGROUND Evidence -based reports are needed to support the application of a one-stage surgical protocol for  unsplinted implants supporting m and ibular overdentures . PURPOSE To examine the feasibility and success of using two different dental implant systems ( originally design ed for two-stage operative technique ) using a one-stage operative procedure in patients being rehabilitated with implant m and ibular overdentures . MATERIAL S AND METHODS The study sample involved 24 edentulous subjects ( aged 55 - 80 yr ) r and omly allocated to two different implant systems , one with a machined titanium implant surface ( Steri-Oss , Nobel Biocare , Göteborg , Sweden ) and the other with a roughened titanium surface ( Southern Implants , Ltd. , Irene , South Africa ) . Two unsplinted implants to support implant overdentures were placed in the anterior m and ible of all patients , using a st and ardized one-stage surgical and prosthodontic procedure . Primary stability and bicortical anchorage of the implants was m and atory before healing abutments were connected at the time of implant placement . Implant overdentures and their respective matrices were inserted following a st and ard 12-week healing period . Data relating to mobility tests , radiographs , and peri-implant parameters were documented at 12 , 16 , and 52 weeks after surgery . RESULTS A success rate of 95.8 % for the Steri-Oss and 100 % for the Southern Implants was found , without any statistically significant differences in the marginal bone loss . Significant changes in Periotest values were observed for both types between 12 and 52 weeks ( p < .001 ) . Minor changes were observed in the peri-implant parameters evaluated . CONCLUSIONS These preliminary findings show a successful application of this one-stage approach for unsplinted implants supporting m and ibular overdentures with Steri-Oss and Southern Implant Systems BACKGROUND Many longitudinal studies of different implant systems have been published but few controlled r and omized investigations have been reported . A 1-year report of a comparative study of ITI Dental Implant System implants ( Straumann AG , Waldenburg , Switzerl and ) and Brånemark System implants ( Nobel Biocare AB , Gothenburg , Sweden ) has been published by the present authors . This paper is a 3-year follow-up of that r and omized study . PURPOSE The aim of the study was to compare the outcome of fixed partial prostheses supported by ITI or Brånemark implants . The outcome was evaluated primarily in terms of survival rates and changes in marginal bone level . MATERIAL AND METHODS The study group comprised 28 patients with anterior residual dentition in the maxilla . The patients were provided with two to  four implants  on each side of the dentition and were r and omly allocated to Brånemark implants or ITI implants ;  77 ITI implants and 73 Brånemark implants  were inserted . After 6 months abutment connections were made to both ITI and Brånemark implants . All patients were provided with fixed partial prostheses of gold-ceramic . The patients were followed up annually with clinical and radiographic examinations for 3 years RESULTS Two Brånemark implants and two ITI implants were lost . The Brånemark implants were lost before loading whereas the ITI implants were lost because of periimplantitis . The survival rate for both groups was 97.3 % . The mean marginal bone level of the Brånemark implants was situated 1.8 mm from the reference point at both the baseline and the 3-year examinations . The corresponding values for the ITI implants were 1.4 mm at baseline and 1.3 mm after 3 years . There was no significant difference between the implant systems with regard to bone level or bone level change . A steady state of the marginal bone level was calculated to have been reached after 3 years for 95.5 % of the Brånemark implants and 87.1 % of the ITI implants .  Periimplantitis ( infection including pus and bone loss ) was observed with seven ITI implants but with none of the Brånemark implants . This difference was statistically significant . CONCLUSIONS No statistically significant differences were found between the implants studied , except for the frequency of periimplantitis , which was higher for the ITI implants . The survival rates were high , and the marginal bone loss was small for both systems The aim of this prospect i ve comparative study was to evaluate the condition of the peri-implant tissues of three different implant systems supporting a m and ibular overdenture . Ninety edentulous patients ( Cawood class V-VI ) participated in this study . After r and omization , 30 patients were treated with 2 Brånemark implants  , 30 patients with 2 IMZ implants  and 30 patients with 2 ITI implants . The implants were inserted in the canine region of the m and ible . After 3 months overdentures were fabricated supported by a round bar and clip attachment . A st and ardized clinical and radiographic evaluation was performed 0,6 and 12 months after insertion of the denture . The intraoral radiographs were made , using the long-cone technique with an aim ing device . Two implants were lost ( 1 Brånemark , 1 IMZ ) during the healing period . None of the patients showed any sensory change in lip or chin region . The pocket depth in the Brånemark group decreased significantly whereas the mucosa recession increased significantly in both the Brånemark as well as in the IMZ group . After 12 months , there was significantly less bone loss in the ITI group . From our study it was concluded that 2 ( Brånemark , IMZ or ITI ) implants placed in the interforaminal region connected with a bar supply a proper base for the support of a m and ibular overdenture in the ( Cawood V-VI ) edentulous patient . The ITI implant appears to be the implant of choice for m and ibular overdenture therapy , because only one operation is required for a comparable result PURPOSE Although no currently available technique for the measurement of osseointegration is entirely satisfactory , 3 clinical variables can be reasonably associated with the process : probing depth , micromobility , and crestal bone height . Micromobility can be quantified to some extent with the use of the Periotest , a commercially available instrument In this investigation , the influence of surface characteristics and geometry upon Periotest value ( PTV ) and probing depth measurements was studied . MATERIAL S AND METHODS In a multicenter trial , 120 healthy edentulous patients received 5 or 6 implants in the anterior m and ible and were followed for 3 years . A total of 634 implants were placed . Every patient received at least 1 implant of each of  
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DISCUSSION AND CONCLUSIONS There were no clinical differences among implant systems .