***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: 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 PURPOSE To evaluate the influence of macro- and microstructure of the implant surface at the marginal bone level after functional loading . MATERIAL S AND METHODS Sixty-eight patients were r and omly assigned to 1 of 3 groups . The first group received 35 implants with a machined neck ( Ankylos ) ; the second group , 34 implants with a rough-surfaced neck ( Stage 1 ) ; and the third , 38 implants with a rough-surfaced neck with microthreads ( Oneplant ) . Clinical and radiographic examinations were conducted at baseline ( implant loading ) and 3 , 6 , and 12 months postloading . Two-way repeated analysis of variance ( ANOVA ) was used to test the significance of marginal bone change of each tested group at baseline , 3 , 6 , and 12 month follow-ups and 1-way ANOVA was also used to compare the bone loss of each time interval within the same implant group ( P < .05 ) . RESULTS At 12 months , significant differences were noted in the amount of alveolar bone loss recorded for the 3 groups ( P < .05 ) . The group with the rough-surfaced microthreaded neck had a mean crestal bone loss of 0.18 + /- 0.16 mm ; the group with the rough-surfaced neck , 0.76 + /- 0.21 mm ; and the group with the machined neck , 1.32 + /- 0.27 mm . In the rough-surfaced group and the rough-surfaced microthreaded group , no statistically significant changes were observed after 3 months , whereas the machined-surface group showed significant bone loss for every interval ( P < .05 ) . DISCUSSION To minimize marginal bone loss , in addition to the use of a rough surface at the marginal bone level , a macroscopic modification such as the addition of microthreads could be recommended . A rough surface and microthreads at the implant neck not only reduce crestal bone loss but also help with early biomechanical adaptation against loading in comparison to the machined neck design . CONCLUSION A rough surface with microthreads at the implant neck was the most effective design to maintain the marginal bone level against functional loading BACKGROUND Brånemark fixtures were originally placed in two stages , whereas titanium plasma-sprayed ( TPS ) solid-screws are placed in one stage . Long-term survival rates for both types of implants are excellent . Excellent survival rates have also been reported for machined screw-shaped ( MS ) titanium implants placed in one stage . A small number of studies have compared different implant systems and methods of implant placement . PURPOSE The purpose of this study is to report clinical outcomes from a prospect i ve longitudinal , multicenter study comparing Brånemark MS fixtures ( Nobel Biocare , Yorba Linda , California , USA ) placed in either one or two stages with a one-stage TPS system ( ITI Straumann , Waldenburg , Switzerl and ) . METHODS A protocol was design ed to compare implant survival rates , changes in crestal bone for titanium MS fixtures placed in one and two stages , and plasma-sprayed solid-screw fixtures placed in one surgical stage .  Twenty-nine patients ranging in age from 24 to 82 years received MS fixtures in one stage .  The average age for males was 58 years ( n = 11 ) , whereas the ages for females ( n = 18 ) ranged from 15 to 84 years ( average 58 years ) . Twenty-nine patients received machined titanium fixtures placed in two stages . There were 20 females ranging in age from 23 to 74 years ( average 54 years ) and 9 females ranging from 24 to 74 years ( average 46 years ) . Twenty-five patients received TPS fixtures .  There were 15 males , ranging in age from 57 to 79 ( average 70 ) , and 10 females , ranging in age from 40 to 83 years ( average 62 years ) .  Bone quality and quantity were determined from radiographs and during site preparation . Patient age , sex , location of implant placement according to jaw , length of fixtures , and number of lost fixtures were entered onto computer code sheets and continuously entered into a locked computer system . For one- and two-stage MS fixtures , nonst and ardized periapical radiographs were taken at abutment connection and follow-up . Solid screws were x-rayed at prostheses connection and follow-up . The average time between implant restoration and radiographic follow-up was 15 months . The x-rays were scanned into a computer , and a program design ed to measure radiographs was used to determine changes in crestal bone . Measurements for one- and two-stage MS fixtures were made from the top of the implant shoulder to the first bone to implant contact mesial and distally . Plasma-sprayed screws were measured from the bottom of the implant to the coronal most bone to implant contacts mesial and distally . Mesial-distal radiographic measurements were averaged and changes were compared using the t-test for related sample s. RESULTS This report presents data from the 2- to 3-year follow-up examinations . Twenty-nine patients received 80 one-stage MS fixtures .  Between 0 and 1 year , two fixtures were lost , result ing in a 97.5 % cumulative survival rate ( CSR ) . The CSR remained unchanged through the 2- to 3-year follow-up . Twenty-eight patients received 78 two-stage MS fixtures . One implant was lost prior to loading and two were lost between 0- and 1-year follow-up , yielding a 96.2 % CSR at the end of 1 year . The CSR remained unchanged through the 2- to 3-year follow-up . Twenty-three patients received 78 solid-screw plasma-sprayed screws . One implant was lost prior to loading and one between the 0- to 1-year follow-up , accounting for a 97.4 % CSR at the 2- to 3-year follow-up . Changes in bone crest measurements for one-stage titanium threaded fixtures were insignificant ( -0.11 mm , p = .08 , maxillary ; 0.07 mm , p = .42 , m and ibular ) . For two-stage MS fixtures , crestal bone loss was insignificant in maxillae ( -0.16 mm , p = .92 ) and significant in m and ibles ( -0.43 mm , p = .000 ) . There was significant bone loss for TPS implants in maxillae and m and ibles ( maxillae , 1.31 mm , p = .04 ; m and ibles , 0.98 mm , p = .000 ) . CONCLUSIONS Cumulative survival rates for MS fixtures placed in one and two stages as well as one-stage TPS screws up to the 2- to 3-year follow-up examination were similar , indicating excellent clinical results . Radiographic measurements for changes in crestal bone loss were clinical ly insignificant for fixtures placed in one stage . For two-stage fixtures , maxillary changes were insignificant , whereas m and ibular bone loss was statistically significant but clinical ly insignificant . Changes in crestal bone loss for TPS implants were statistically significant BACKGROUND Interest in the use of one-stage surgery and immediate loading of oral implants has lately been increasing . PURPOSE The aim of this study was to compare the 3-year results of one-stage surgery versus two-stage surgery , early loading versus loading after a 3-month healing period , and the use of one-piece implants versus the use of two-piece implants . MATERIAL S AND METHODS The study included 108 patients with edentulous m and ibles . Each patient was treated with four Brånemark System implants ( Nobel Biocare AB , Göteborg , Sweden ) and with full fixed prostheses . Patients were consecutively treated and were distributed in four groups : group A ( one-stage surgery ) , group B ( control group with two-stage surgery ) , group C ( one-piece implants ) , and group D ( early loading ) . In groups A and B Brånemark St and ard implants and st and ard abutments were used . In group C the conical one-piece Brånemark implant was used , and in group D the patients had Brånemark System Mk III implants together with multiunit abutments . All patients were observed for 3 years . RESULTS Of the 432 inserted implants , 24 were lost . Survival rates in the three experimental groups ranged from 93.2 to 93.3 % whereas the survival rate in group B ( the control group with two-stage surgery ) was 97.5 % . The differences between the groups were not statistically significant . The changes in marginal bone level were measured from fixture insertion to the final follow-up at 3 years . The bone loss in group D ( early loading ) was significantly less than in group B ( the control group ) whereas there were no differences in marginal bone change between the other groups . CONCLUSIONS Early loading seemed to give good results in the anterior part of the m and ible . The survival rate of the early-loaded implants did not significantly differ from that of implants inserted with the conventional two-stage procedure , but the mean marginal bone loss around the surviving implants was less with early loading 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 In the present multi-center study , non-submerged ITI implants were prospect ively followed to evaluate their long-term prognosis in fully and partially edentulous patients . In a total of 1003 patients , 2359 implants were consecutively inserted . Following a healing period of 3 - 6 months , the successfully integrated implants were restored with 393 removable and 758 fixed restorations . Subsequently , all consecutive implants were documented annually up to  
    Output:
    
No statistically significant differences in bone loss and survival rates were detected between BL and TL dental implants over a short-term observation period ( 1 to 3 years ) .
Thus , both implant systems fulfill the requirements for the replacement of missing teeth in implant dentistry