***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: OBJECTIVES This r and omised , controlled multicentre trial aim ed at comparing two versions of a variable-thread dental implant design to a st and ard tapered dental implant design in cases of immediate functional loading for 36 months after loading . MATERIAL S AND METHODS 177 patients ( 325 implants ) were included at 12 study centres and r and omly allocated into one of three treatment groups : NAI ( variable-thread design , NobelActive internal connection ) , NAE ( variable-thread design , NobelActive external connection ) and , as control , NR ( st and ard tapered design , NobelReplace tapered groovy ) . Inclusion criteria concerned healed bony implant sites and feasibility for immediate loading . Clinical and radiographic examinations were performed at implant placement and after 3 , 6 , 12 , 24 and 36 months . The outcome measures were marginal bone remodelling ( primary outcome ) , implant survival and success , papilla score , plaque accumulation , and bleeding on probing . RESULTS 127 patients ( NAI : 45 , NAE : 41 , NR : 41 ) were followed-up and evaluated after 36 months . No significant differences in cumulative survival rates were seen for the groups ( NAI : 95.7 % ; NAE : 96.3 % ; NR : 96.6 % ) . In all groups , bone remodelling occurred during the first 3 months , with stable or even increasing bone levels after the initial remodelling period . The bone remodelling from insertion to 36 months for the NAI group ( -0.89 ± 1.65 mm ) was comparable ( P = 0.98 ) to that of the NR group ( -0.85 ± 1.32 mm ) . The NAE group showed comparable bone remodelling during the first year , with an increase in following years result ing in significantly less overall bone loss ( -0.16 ± 1.06 mm ) ( P = 0.041 ) . Overall improvement in papilla size was observed in all treatment groups . CONCLUSIONS Over 36 months , the results show stable or improving bone levels for all treatment groups after the initial bone remodelling seen during the first 3 months after placement . The variable- thread implants showed results comparable to those of st and ard tapered implants in cases of immediate function , and therefore can be considered as a treatment option for immediate loading OBJECTIVES The aim of this prospect i ve study was to assess the effects of abutment removal after 6 months on bone healing after the subcrestal placement of immediately restored , tapered implants in cases of partial posterior m and ibular edentulism . MATERIAL AND METHODS Each of the 24 patients with partial posterior m and ibular edentulism was consecutively treated with two immediately restored 3.5 mm diameter tapered implants . A total of 48 implants were placed in healed sites and immediately splinted with a temporary restoration , which was placed in such a way as to avoid occlusal contact . Twenty-four weeks after surgery , 12 patients underwent the st and ard prosthetic protocol : the abutments were removed and impressions were made directly on the implant platform . Twelve patients underwent the " one abutment at one time " protocol : impressions were made of the abutments using snap-on abutment copies . The final restoration was delivered approximately 6 months after implant insertion . Vertical and horizontal bone changes were assessed using periapical radiographs immediately after surgery and at 6- , 12- , 24- and 36-month follow-up examinations . RESULTS All implants osseointegrated and were clinical ly stable at the 6-month follow-up . No statistically significant difference was evidence d between the two groups regarding the measurement of vertical bone healing . A small but significant horizontal bone loss was evidence d in the hard tissue portion over the implant platform in the period of time between the 6-month and 1-year follow-up in the control group . CONCLUSIONS The non-removal of an abutment placed at the time of surgery results in a statistically significant reduction of the horizontal bone remodeling around the immediately restored , subcrestally placed , tapered implant in cases of partial posterior m and ibular edentulism PURPOSE To compare the clinical and radiological outcomes of two implant design s with different prosthetic interfaces and neck configurations . MATERIAL S AND METHODS Thirty-four partially edentate patients r and omly received at least one NobelActive implant ( Nobel Biocare  , Göteborg , Sweden ) with back-tapered collar , internal conical connection and platform shifting design , and one NobelSpeedy implant ( Nobel Biocare ) with external hexagon and flat-to-flat implant-abutment interface according to a split-mouth design . Follow-up continued to 3 years post-loading . The primary outcome measures were the success rates of the implants and prostheses , and the occurrence of any surgical and prosthetic complications during the entire follow-up . Secondary outcome measures were : horizontal and vertical peri-implant marginal bone level ( MBL ) changes , resonance frequency analysis values at implant placement and loading ( 4 months ) , sulcus bleeding index ( SBI ) and plaque score ( PS ) . RESULTS No drop-out occurred . No implants and prostheses failures were observed to the 3-year follow-up . MBL changes were statistically significant different with better results for the NobelActive implants for both horizontal and vertical measurements ( P = 0.000 ) . After 3 years post-loading , the NobelActive implants underwent a mean vertical bone resorption of 0.66 mm , compared with 1.25 mm for the NobelSpeedy Groovy implants ( P = 0.000 ) ; the mean horizontal bone resorption was 0.19 mm for the NobelActive implants and 0.60 mm for the NobelSpeedy Groovy implants ( P = 0.000 ) . A high ISQ value was found for both implants , and no statistically significant difference was found for ISQ mean values between interventions ( P = 0.941 at baseline ; P = 0.454 at implantabutment connection ; P = 0.120 at prosthesis delivery ) . All implants showed good periodontal health at the 3-year-in-function visit , with no significant differences between groups . CONCLUSION The results of this research suggest that in well-maintained patients , the MBL changes could be affected by the different implant design . After 4 months of unloaded healing , as well as after 3 years in function , both implants provided good results , however vertical and horizontal bone loss had statistically significant differences between the two groups ( difference of 0.58 ± 0.10 mm for the vertical MBL , and 0.4 ± 0.05 mm for the horizontal MBL ) , with lower values in the Nobel Active implants , compared to the NobelSpeedy Groovy implants OBJECTIVE To carry out a comparative study of two implants with different neck features and prostheses platform connection ( machined with external connection and rough-surfaced with switching platform ) upon peri-implant marginal bone loss , before and after functional loading . MATERIAL AND METHODS A r and omized , prospect i ve radiological study was made . Eighteen totally edentulous patients were selected . Subjects were divided into two groups according to the type of implant neck used : ( a ) Osseous ( ® ) , with machined surface , without microthreads , external connection , and without platform switching ; and ( b ) Inhex ( ® ) , with treated surface , microthreads , internal connection , and platform switching . Mesial and distal marginal bone loss was measured . Implant success was assessed according to the criteria of Buser . Control timepoints were as follows : ( a ) at implant placement ; ( b ) at prosthesis placement ; ( c ) 6 months after loading ; ( d ) 12 months after loading . RESULTS Fifteen patients that received 120 dental implants were included : 47 % Osseous ( ® ) group and 53 % Inhex ( ® ) group . Global mean marginal bone loss with Osseous ( ® ) was 0.27 ± 0.43 mm and 0.38 ± 0.51 mm as determined 6 and 12 months after prosthetic loading , respectively , whereas in the case of Inhex ( ® ) was 0.07 ± 0.13 and 0.12 ± 0.17 mm . These differences were statistically significant ( P = 0.047 ) . Difference between Osseous ( ® ) and Inhex ( ® ) in maxilla ( P = 0.272 ) and m and ibular ( P = 0.462 ) bone loss were not statistically significant . CONCLUSIONS Bone loss after 6 and 12 months proved statistically significant between two groups , with comparatively greater loss in the case of Osseous ( ® ) implants vs. Inhex ( ® ) implants . Regardless the heterogeneity of the two groups ( neck shape , microthreads , surface texture ) , the implant-abutment connection appears to be a significant factor on peri-implant crestal bone levels . Anyway , in both groups , the values obtained were within normal ranges described in the literature BACKGROUND Peri-implant bone loss seems to occur following implant placement/loading regardless of all the efforts to eliminate it . Several factors , including surgical trauma , biologic width establishment , lack of passive fit of the superstructures , implant-abutment microgap , and occlusal overloading , may increase peri-implant bone loss . Over the years , new interface design s were introduced and clinical studies suggest that internal conical connection and platform shifting may be advantageous for marginal bone preservation . PURPOSE To compare clinical and radiological outcomes of two implant design s with different prosthetic interfaces and neck configurations in a r and omized , controlled , split-mouth clinical trial . MATERIAL S AND METHODS Thirty-four partially edentate patients r and omly received at least one  internal conical connection with back-tapered collar and platform shifting design or external-hexagon implants with flat-to-flat implant-abutment interface . Primary end point was peri-implant bone level changes at different time points , failures of implants and /or prosthesis , any complications , implant stability quotient ( ISQ ) values , and periodontal parameters . RESULTS No dropout occurred . Marginal bone changes were statistically significantly different with better results for the internal conical connection . No implants and prosthesis failures have been observed , yielding a cumulative survival rate of 100 % . A high ISQ value was found for both implants , and no statistically significant difference was found for ISQ mean values between interventions at each time point ( p > .05 ) . All implants showed no bleeding on probing and a very slight amount of plaque at the 1-year-in-function visit . CONCLUSIONS Both implant design s investigated performed similarly in terms of failure rates , providing successful results up to 1 year after loading . The back-tapered neck configuration with conical connection and built-in platform shifting showed statistically lower marginal bone loss than straight neck configuration with flat-to-flat implant-abutment interface and external-hexagonal connection PURPOSE To evaluate advantages and disadvantages of identical implants with internal or external connections . MATERIAL S AND METHODS One hundred and twenty patients with any type of edentulism ( single tooth , partial and total edentulism ) , requiring one implant-supported prosthesis were r and omly allocated in two equal groups to receive either implants with an external connection ( EC ) or implants of the same type with an internal connection ( IC ) ( EZ Plus , MegaGen Implant , Gyeongbuk , South Korea ) , at four centres . Due to slight differences in implant design and components , IC implants were platformswitched while EC were not . Patients were followed for 5 years after initial loading . Outcome measures were prosthesis/implant failures , any complication , marginal bone level changes and clinician preference , assessed by blinded outcome assessors . RESULTS Sixty patients received 96  EC implants and 60 patients received 107 IC implants . Three patients dropped out with four EC implants and five patients with ten IC implants , but all remaining patients were followed up to 5-year post-loading . One prosthesis supported by EC implants and two by IC implants  failed ( P = 0.615 , difference = -0.02 , 95 % CI : -0.08 to 0.04 ) . One EC implant failed versus three IC implants in two patients ( P = 0.615 , difference = -0.02 , 95 % CI : -0.08 to 0.04 ) . Ten complications occurred in 10 EC patients versus nine complications in 9 IC patients ( P = 1.000 , difference = 0.01 , 95 % CI : -0.13 to 0.15 ) . There were no statistically significant differences for prosthesis and implant failures and complications between the different connection types . Five years after loading , there were no statistically significant differences in marginal bone level estimates between the two groups ( difference = 0.14 mm , 95 % CI : -0.28 to 0.56 , P ( ancova ) = 0.505 ) and both groups lost bone from implant placement in a statistically significant way : 1.13 mm for the EC implants and 1.21 mm for the IC implants . Two operators had no preference and two preferred IC implants . CONCLUSIONS Within the limitations given by the difference in neck design and platform switching between EC and IC implants , 5-year post-loading data did not show any statistically significant differences between the two connection types , therefore clinicians could choose whichever they preferred BACKGROUND Today , implants are placed using both non-submerged and submerged approaches , and in 1- and 2-piece configurations . Previous work has demonstrated that peri-implant crestal bone reactions differ radiographically under such conditions and are dependent on a rough/smooth implant border in 1-piece implants and on the location of the interface ( microgap ) between the implant and abutment/restoration in 2-pie 
    Output:
    
The network meta- analysis ( NMA ) suggested a significant difference between the external and the conical connections ; this was less evident for the internal and conical ones .
Platform-switching ( PS ) seemed to positively affect bone levels , non-regarding the implant-connection it was applied to .
Within the limitations of this systematic review , it can be concluded that crestal bone levels are better maintained in the short-medium term when internal kinds of interface are adopted .