title: Strain characteristics of Marburg double crown-retained implant overdentures compared with bar and ball-retained implant overdentures, with and without a rigid major connector.
abstract: BACKGROUND
  It is hard to identify the most favorable retainer type and the denture design when considering strain levels around implants and in edentulous ridges for implant overdentures (IOVD).
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the strain transmitted to the implants and edentulous ridges by Marburg double crown (MDC)-retained IOVD as opposed to bar and ball-retained IOVD and the efficiency of a rigid major connector in the maxilla.
  
  
  METHODS
  An in vitro maxillary model was prepared with 4 implants, with strain gauges placed distally to each implant and also in the anterior and posterior edentulous ridges. Five overdentures were fabricated for each MDC and each ball and bar attachment retainers. Vertical loads of 280 N were applied bilaterally on the first molar region. Then the palatal bars of each IOVD were disconnected, and loading procedures were repeated for the prostheses.
  
  
  RESULTS
  No significant difference was observed among the MDC and the bar and ball-retained IOVD, with and without a rigid bar according to the data taken from both the implants and edentulous ridges. However, when the strain values attained from each strain gauge separately were considered, a slight difference was observed around the implants of ball-retained overdentures and in the edentulous ridges of MDC-retained overdentures.
  
  
  CONCLUSIONS
  Within the limitations of this in vitro study, MDC-retained maxillary overdentures with 4 parallel and symmetrically placed implants can be used safely without a rigid major connector as with bar and ball-retained IOVD with regard to the strains generated in the edentulous ridge and around implants.
authors: Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Okan University, Istanbul, Turkey. Electronic address: sehnazkazok@yahoo.com.
authors: F Şehnaz
authors: FŞ
authors: Kazokoğlu
authors: Professor, Department of Prosthodontics, Faculty of Dentistry, Ankara University, Ankara, Turkey.
authors: Funda
authors: F
authors: Akaltan
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry; D003442:Crowns; D059605:Dental Implant-Abutment Design; D003764:Dental Materials / Q000737:chemistry; D019094:Dental Prosthesis, Implant-Supported; D003819:Denture Bases; D003779:Denture Design; D003781:Denture Retention / Q000295:instrumentation*; D003828:Denture, Overlay; D006801:Humans; D007575:Jaw, Edentulous / Q000473:pathology; D008422:Materials Testing; D008437:Maxilla / Q000473:pathology; D008953:Models, Anatomic; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry
chemical_list: D002858:Chromium Alloys; D003764:Dental Materials; D014025:Titanium