J Korean Acad Prosthodont.  2008 Apr;46(2):169-174.

Radiographic evaluation of marginal bone resorption around two types of external hex implants: preliminary study

  • 1Department of Prosthodontics, College of Dentistry, Seoul National University, Seoul, Korea. 0504heo@hanmail.net
  • 2Department of Prsthodontics, College of Dentistry, Yongdong Severance Hospital, College of Dentistry, Yonsei University, Seoul, Korea.


STATEMENT OF PROBLEM: Changes of the marginal bone around dental implants have significance not only for the functional maintenance but also for the esthetic success of the implant. It was proposed that bone-retention elements such as microthreads at the coronal part of implant might help maintain the marginal bone level. PURPOSE: This study was designed to evaluate the effect of microthread configuration within the marginal coronal portion of the implant fixture at the marginal bone changes after loading around two different external hex implants. MATERIAL AND METHODS: Twenty-four patients were included and randomly assigned to treatment with Branemark system implants (Group 1, rough-surfaced implants, n=20) and Oneplant system implants (Group 2, rough-surfaced neck with microthreads, n=20). Clinical and radiographic examinations were conducted at baseline (implant loading) and 1 year postloading. Data analysis was performed by the SAS statistical package version 9.1.3 (SAS Institute, Cary, NC, USA) and the final model was calculated by the MIXED procedure (three-level ANCOVA) for marginal bone change of each test group at baseline and 1 year follow-up.
Comparing to baseline, significant differences were noted in marginal bone level changes for the 2 groups at 1 year follow-up (P<0.05). Group 1 had a mean crestal bone level changes of 0.83+/-0.31mm; Group 2 had a mean crestal bone level changes of 0.44+/-0.36mm. Rough-surfaced with microthreads implants showed significantly less marginal bone loss than rough surfaced neck without microthread implants.
A rough surface with microthreads at the implant was beneficial design to maintain the marginal bone level against functional loading.


Marginal bone level; Microthreads; Rough surface
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