***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 In the presence of a thin and narrow zone of gingival tissue root recessions caused by trauma or inflammatory reactions seem to be a common feature of the buccal tissue morphology . The surgical coverage is mainly indicated for aesthetic reasons and may be accomplished with pedicled flaps in conjunction with or without the use of connective tissue grafts . AIM The purpose of the present study was to evaluate the degree of vascularization of connective tissue grafts by applying a microsurgical approach . In addition , the clinical outcome was followed for 1 year . MATERIAL AND METHODS The study population consisted of 10 patients with bilateral Class I and II recessions at maxillary canines . In split-mouth design , the defects were r and omly selected for recession coverage either by a microsurgical ( test ) or macrosurgical ( control ) approach . Immediately after the surgical procedures , and after 3 and 7 days of healing , fluorescent angiograms were performed to evaluate graft vascularization . In addition , the clinical parameters were assessed before the surgical intervention , and 1 , 3 , 6 and 12 months postoperatively . RESULTS The results of the angiographic evaluation at test sites revealed a vascularization of 8.9+/-1.9 % immediately after the procedure . After 3 days and after 7 days , the vascularization rose to 53.3+/-10.5 % and 84.8+/-13.5 % , respectively . The corresponding vascularization at control sites were 7.95+/-1.8%/44.5+/-5.7 % and 64.0+/-12.3 % , respectively . All the differences between test and control sites were statistically significant . The clinical measurements revealed a mean recession coverage of 99.4+/-1.7 % for the test and 90.8+/-12.1 % for the control sites after the first month of healing . Again , this difference was statistically significant . The percentage of root coverage both test and control sites remained stable during the first year at 98 % and 90 % , respectively . CONCLUSIONS The present controlled clinical study has demonstrated that in root surface coverage , a microsurgical approach substantially improved the vascularization of the grafts and the percentages of root coverage compared with applying a conventional macroscopic approach The etiologic factors associated with  crestal bone loss  have not been comprehensively clarified . Several theories exist as to the reason for the observed changes in crestal bone height following implant restoration . In the 1990s , the wide-diameter implants were commercially introduced . Initially , the implants were restored with st and ard-diameter abutments because of lack of matching prosthetic components . Long-term radiographic follow-up of these ' platform-switched ' restored wide-diameter dental implants has demonstrated a smaller-than-expected vertical change in the crestal bone height around these implants that is typically observed around implants restored conventionally with prosthetic components of matching diameters . The aim of this r and omised controlled study was to assess radiographically marginal bone level alterations in implants restored according to the platform-switching concept compared with traditionally restored implants . Fifty-four subjects to participate in this r and omised controlled study were selected . Two groups were assigned at r and om : control group ( 56 implants were restored with st and ard matching-diameter abutments ) and test group ( 58 implants were restored with medialised abutments ) . X-ray explorations were taken for peri-implant bone level at the minute the last cementing of the prosthesis and at 1-year follow-up . NHI Image was used to digitally process and manipulate the radiographic images and perform the measurements . Mean of bone loss with platform-switching implants was -0·01 mm , and the mean of bone loss with st and ard platform implant was 0·42 mm . Outcomes of this study indicated that the platform-switching design could preserve the crestal bone levels to 1-year follow-up . There was a statistically significant difference in marginal bone loss 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 Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more PURPOSE Several long-term clinical studies have shown a mean marginal bone loss around dental implants of 1.5 to 2 mm in the first year after prosthetic restoration . Currently , concepts to avoid bone remodeling around dental implants have been developed . The use of prosthetic abutments with reduced width in relation to the implant diameter ( platform switching ) seems to have the greatest potential to limit the crestal resorption . The purpose of this clinical trial was to show that crestal bone height around dental implants  could be influenced using a platform switch protocol and that the bone level would remain stable within 1 year after final prosthetic reconstruction . MATERIAL S AND METHODS Fifteen patients were treated with fixed implant retained prosthesis ; 14  wide-diameter implants were supplied with platform-switched abutments and served as the test group . Eight implants with regular diameter were reconstructed with traditional abutments and served as the control group . St and ardized digital radiographs were obtained for evaluation of the peri-implant bone levels at the time of installation of the final restoration and at 1-year follow-up . Marginal peri-implant bone levels were measured at the mesial and distal surfaces of each implant using digital image analysis . RESULTS The mean values of crestal bone height at baseline were -0.09 mm + /- 0.65 mm for the platform-switched implants and -1.73 mm + /- 0.46 mm for the nonplatform-switched implants . One year after final restoration , the mean value of crestal bone height was -0.22 mm + /- 0.53 mm for the test group and -2.02 mm + /- 0.49 mm for the control group . When tested with statistical means , the differences were significant for baseline and for follow-up ( P < /= .0001 ) . Mean bone level change from baseline to 1-year follow-up was -0.12 mm + /- 0.40 mm for the test group and -0.29 mm + /- 0.34 mm , respectively , for the control group . On analysis using ANCOVA , this difference was shown to be significant ( P < /= .0132 ) . CONCLUSION The concept of platform switching appears to limit crestal resorption and seems to preserve peri-implant bone levels . A certain amount of bone remodeling 1 year after final reconstruction occurs , but significant differences concerning the peri-implant bone height compared with the nonplatform-switched abutments are still evident 1 year after final restoration . The reduction of the abutment of 0.45 mm on each side ( 5 mm implant/4.1 mm abutment ) seems sufficient to avoid peri-implant bone loss PURPOSE To evaluate whether platform switching could preserve marginal bone around implants up to 6 months after loading . MATERIAL S AND METHODS 15 patients were selected for a r and omised controlled trial . Each patient received one customised wide body implant , with the external hex connection located eccentrically , allowing an extra 1 mm switch on one side . The hex was positioned at r and om at the mesial or distal side and the implant was loaded after 6 months of non-submerged healing . Patients were examined at 3 , 6 and 12 months after surgery , during which a radiograph was taken to evaluate bone levels . At 12 months , the mucosal thickness was measured using a perio-probe . RESULTS All implants survived and the mean overall bone loss , calculated from both the switched and non-switched side , was 0.39 mm ( SD 0.33 , range 0.00 - 1.45 ) , 0.85 mm ( SD 0.59 , range 0.10 - 2.50 ) and 0.80 mm ( SD 0.46 , 0.26 - 1.89 ) after 3 , 6 and 12 months , respectively . The bone loss continued up to 6 months but stabilised thereafter ( P = 0.615 ) . Significantly more bone loss was observed at the non-switched side compared to the switched side at 3 months ( 0.51 mm versus 0.28 mm , P = 0.019 ) , 6 months ( 1.05 mm versus 0.64 mm , P = 0.002 ) and 12 months ( 0.94 mm versus 0.66 mm , P = 0.002 ) . The mean mucosal thickness was 4.22 mm ( SD 1.45 ; range 1.50 - 7.00 ) , and was not significantly different between the switched and non-switched sides ( P = 0.882 ) . However , using a post-hoc analysis with the mean thickness as a threshold , the mean bone loss was only significantly different between switched and non-switched sides when the mucosa was thicker than 4.22 mm ( P = 0.036 ) . CONCLUSIONS The outcome of this r and omised trial is in accordance with earlier studies suggesting that that platform switching decreases bone loss by 30 % . Although the sample size was limited , it seems that the creation of a biologic width affects peri-implant bone loss to a significant extent and that platform switching is only effective when the mucosal thickness allows the establishment of a biologic width The aim of this study was to evaluate the change of marginal bone level radiographically around three different implant systems after 3 years in function . Fifty-four patients were included and r and omly assigned to three treatment groups of rough-surface implants ( TiUnite , n = 37 ) , hybrid of smooth and rough-surface implants ( Restore , n = 38 ) and rough surface with microthread implants ( Hexplant , n = 45 ) . Clinical and radiographic examinations were conducted at the time of implant loading ( baseline ) , 1 and 3 years after loading . A three-level mixed-effect analysis of covariance ( ancova ) was used to test the significance of the mean marginal bone change of the three implant groups . A total 120 of 135 implants completed the study . None of the implants failed to integrate . Significant differences were noted in the marginal bone loss recorded for the three groups ( P < 0.0001 ) . At 3 years , the rough surface with microthread implants had a mean crestal bone loss of 0.59 + /- 0.30 mm ; the rough-surface implants , 0.95 + /- 0.27 mm ; and the hybrid surface implants , 1.05 + /- 0.34 mm . Within the limitations of this study , rough-surface implants with microthread at the coronal part might have a long-term positive effect in maintaining the marginal bone level against functional loading in comparison with implants without these two features PURPOSE The purpose of this study was to evaluate the effectiveness of the platform-switching technique to prevent crestal bone loss following the restoration of dental implants . MATERIAL S AND METHODS This r and omized prospect i ve multicenter trial analyzed 60 partially edentulous adults recruited at 12 professional dental centers . Subjects were r and omly selected to receive either platform-enlarged or control cylindric implants in three different surgical procedures : conventional nonsubmerged , submerged , and submerged with a reduced abutment . The primary outcome measure was the change in crestal bone level assessed radiographically 12 and 24 months following placement . Nonparametric analysis of variance for repeated measures ( the Friedman test ) was used to assess the overall significance over time of the differences among implants in changes 
    Output:
    
Dental implants at bone level show significantly less crestal bone change after 1 year of loading than tissue-level implants