title: Effect of splinting mini-implants on marginal bone loss: a biomechanical model and clinical randomized study with mandibular overdentures.
abstract: OBJECTIVE
  This aim of this study was to evaluate the effect of splinting mini-implants on marginal bone loss when used to retain mandibular overdentures.
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Center for Advanced Prosthodontic and Implantology, CRAI, University of Concepcion, Chile. jjofre@udec.cl
authors.forename: Jorge
authors.initials: J
authors.lastname: Jofre
authors.forename: Patricio
authors.initials: P
authors.lastname: Cendoya
authors.forename: Paola
authors.initials: P
authors.lastname: Munoz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D001696:Biomechanical Phenomena; D003758:Dental Implantation, Endosseous / Q000295:instrumentation / Q000379:methods; D015921:Dental Implants / Q000009:adverse effects; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported / Q000009:adverse effects; D003799:Dental Stress Analysis; D003781:Denture Retention / Q000295:instrumentation; D003828:Denture, Overlay; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D007575:Jaw, Edentulous / Q000473:pathology / Q000534:rehabilitation; D008137:Longitudinal Studies; D008297:Male; D008334:Mandible / Q000473:pathology / Q000601:surgery; D008875:Middle Aged; D008962:Models, Theoretical; D013516:Oral Surgical Procedures, Preprosthetic / Q000295:instrumentation / Q000379:methods; D013165:Splints; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants