Effect of splinting mini-implants on marginal bone loss: a biomechanical model and clinical randomized study with mandibular overdentures

Abstract

Purpose This aim of this study was to evaluate the effect of splinting mini implants on marginal bone loss when used to retain mandibular overdentures Materials and Methods With mathematical models, a finite element analysis was performed to compare the bone stress distribution around two mini implants, either splinted with a bar superstructure or not splinted In the clinical portion of this study, 90 mini implants were placed in the anterior mandibles of 45 completely edentulous patients selected from a public health center Patients were randomly allocated into two groups Group-ball (22 patients, n = 44) received two single ball type mini implants, and group bar (23 patients, n = 46) received two mini implants splinted with a prefabricated bar All implants were placed using a flapless technique and loaded immediately Marginal bone loss was assessed through standardized retroalveolar radiographs of each mini implant and compared 5, 10, 15, and 24 months after implant placement Results The finite element analysis showed the highest minimum principal stress (-118 MPa) in bone surrounding the unsplinted mini implant, while around the splinted implants the principal stresses were -56 8 MPa After 2 years of follow up in the clinical study, group-ball showed a trend toward greater marginal bone loss than group-bar (1 43 +/- 1 26 mm and 0 92 +/- 0 75 mm, respectively) Group ball showed a significantly higher prevalence of vertical bone loss than group bar (chi square test, two-tailed) Conclusion Splinted mini implants with a rigid superstructure decrease the bone stress level in comparison with single mini implants The effects of bone stress magnitude may explain the clinical outcome, in which splinted mini implants supporting a mandibular overdenture showed less marginal bone loss compared with nonsplinted mini implants Vertical bone resorption morphology was significantly more prevalent in the latter group INT J ORAL MAXILLOFAC IMPLANTS 2010 25 1137-1144