Statement of problem
Attachments for mandibular overdentures may not allow for adequate freedom of rotation.
Purpose
The purpose of this study was to subject 3 commonly used stud types of resilient attachments
to rotation and to measure and compare the degree of rotation that occurs before the
attachments bind.
Material and methods
Three stud attachments (ERA, Locator Extended Range, O-Ring System) with their corresponding
metal housings were evaluated, first for a single implant system and secondly for
a 2-attachment parallel implant system for the mandibular arch. Both the manufacturers'
most and least retentive components were tested in each system. In the Locator system,
the medium retention (3 lbs) for the standard is the most retentive of the extended
range. A total of 60 test specimens, 5 per group, were fabricated. The attachments
were connected to a 115-mm rod and attached to a testing device composed of a base,
implant analogs, and a vertical plate holding graph paper. A free-sliding plastic
block, which supported the metal rod parallel to the base, was removed to release
the rod. The distance the rod fell was photographed and input into a computer with
software designed to measure linear movement. Three-way ANOVA with heteroscedasticity
consistent standard errors was used for data analyses (α=.05).
Results
Significant differences found among the most retentive components showed that the
Locator had a greater freedom of rotation than the ERA (P=.001). The most retentive components in all systems showed that 1 attachment had
a greater freedom of rotation than 2 (P=.005). When testing the least retentive components, all systems were significantly
different (P<.003), with the freedom of rotation ranking being O-Ring System > Locator Extended
Range > ERA. For all 3 systems, the least retentive components showed the most freedom
(P≤.008).
Conclusions
The least retentive components offer greater rotation than the most retentive components
for all attachment systems tested and for both single and double attachments. Using
the most retentive components, the Locator Extended Range attachment allows greater
rotation than does the ERA for both single and double attachments. Using the least
retentive components, the ORS attachment allows the most rotation and ERA the least
for both single and double attachments. Using the most retentive components, one attachment
allows greater rotation than does 2 attachments for the attachment systems evaluated.
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Article info
Footnotes
Presented to the Pacific Coast Society of Prosthodontics in Napa Valley 2010.
Identification
Copyright
© 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.
