Journal of Dental Research, Vol 55, 783-786, Copyright © 1976 by International & American Associations for Dental Research Online Journals
Load-extension-time behavior of orthodontic Alastiks
J. S. Kovatch, E. P. Lautenschlager, D. A. Apfel and J. C. Keller
Typical elastomeric behavior displayed by Alastik orthodontic bands
resulted in load-extension curves that depended on the rate of extension as
well as the amount of extension. Initially, the modules tested at the
faster speeds had higher moduli and were stronger; but as extension
continued, the trend reversed, and at breakage the more slowly stretched
modules were the strongest. Therefore, although the Alastiks appear to be
uniformly produced, the clinician still needs to know his rate of
deformation and degree of stretching to accurately assess the module force.
In addition, the module, once in position, will not maintain a constant
force but will experience a decrease in applied load with time kept at a
constant extension. Because the initial load decay is more rapid for both
faster extension and higher load, it seems reasonable to suggest that care
be taken by the clinican to stretch the module more slowly into place. This
should result in a higher load level for a longer period of time. Although
the measured changes in loads are not necessarily of sufficient magnitude
to seriously influence the clinical result, a clearer understanding of the
module behavior, such as currently presented, will hopefully assist in more
comprehensive clinical evaluations.
