title: Comparison of load distribution for implant overdenture attachments.
abstract: OBJECTIVE
  The aim of this study was to compare the force and moment distributions that develop on different implant overdenture attachments when vertical compressive forces are applied to an implant-retained overdenture.
  
  
  METHODS
  The following attachments were examined: Nobel Biocare bar and clip (NBC), Nobel Biocare standard ball (NSB), Nobel Biocare 2.25-mm-diameter ball (NB2), Zest Anchor Advanced Generation (ZAAG), Sterngold ERA white (SEW), Sterngold ERA orange (SEO), Compliant Keeper System with titanium shims (CK-Ti), Compliant Keeper System with black nitrile 2SR90 sleeve rings (CK-70), and Compliant Keeper System with clear silicone 2SR90 sleeve rings (CK-90). The attachments were tested using custom strain-gauged abutments and 2 Brånemark System implants placed in a test model. Each attachment type had one part embedded in a denture-like housing and the other part (the abutment) screwed into the implants. Compressive static loads of 100 N were applied (1) bilaterally, over the distal midline (DM); (2) unilaterally, over the right implant (RI); (3) unilaterally, over the left implant (LI); and (4) between implants in the mid-anterior region (MA). Both the force and bending moment on each implant were recorded for each loading location and attachment type. Results were analyzed using 2-way analysis of variance and the Duncan multiple-range test.
  
  
  RESULTS
  Both loading location and attachment type were statistically significant factors (P < .05). In general, the force and moment on an implant were greater when the load was applied directly over the implant or at MA.
  
  
  CONCLUSIONS
  While not significant at every loading location, the largest implant forces tended to occur with ZAAG attachments; the smallest were found with the SEW, the SEO, the NSB, the CK-70, and the CK-90. Typically, higher moments existed for NBC and ZAAG, while lower moments existed for SEW, SEO, NSB, CK-90, and CK-70.
  
  
  CONCLUSIONS
  For different loading locations, significant differences were found among the different overdenture attachment systems.
authors.affiliation: Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Porter
authors.forename: Vicki C
authors.initials: VC
authors.lastname: Petropoulos
authors.forename: John B
authors.initials: JB
authors.lastname: Brunski
mesh_terms: D000704:Analysis of Variance; D001732:Bite Force; D002858:Chromium Alloys / Q000737:chemistry; D000044:Dental Abutments; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003819:Denture Bases; D003779:Denture Design; D003781:Denture Retention; D003828:Denture, Overlay; D006801:Humans; D003765:Models, Dental; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D016474:Weight-Bearing
chemical_list: D002858:Chromium Alloys; D015921:Dental Implants