Journal of Dental Research, Vol 70, 870-873, Copyright © 1991 by International & American Associations for Dental Research Online Journals
An in vivo and in vitro study of the loss of plasticizer from soft polymer-gel materials
B. S. Graham, D. W. Jones and E. J. Sutow
Department of Restorative Dentistry, Faculty of Dentistry, Dalhousie University, Halifax, Nova Scotia, Canada.
Polymer-gel materials used as short-term denture soft linings are blended
with plasticizers to lower the glass transition temperature (Tg). A lower
Tg allows for greater polymer chain mobility, thus producing a more
flexible material. The present work evaluated the loss of plasticizers due
to leaching both in vivo and in vitro. Two commercial denture soft-lining
materials (A and B) were tested. These were both poly(ethyl methacrylate)
polymers, blended with alcohol and phthalate esters. A clinical study was
conducted in which patients wore, sequentially, dentures bearing (on
separate occasions) each of the two soft-polymer lining materials. The two
materials A and B were randomly assigned for each of ten patients and were
worn for 14 and 30 days, respectively. With one exception, patients wore
dentures with both lining materials, for a total of 19 clinical
evaluations. The plasticizer loss occurring during the clinical trial was
determined by GC analysis from the initial and terminal day sampling of
plasticizer content of the soft polymer-gel materials. The results of this
analysis were compared with results obtained from an in vitro leachability
study by use of sink conditions in water at 37 degrees C for the same two
commercial soft polymers conducted over the same time periods of 14 and 30
days. The results indicated that a higher loss of plasticizer occurred in
vivo, compared with the in vitro tests for 17 of the 19 clinical
evaluations. The average plasticizer lost in vivo from material A at 14
days was 122 +/- 58 mg/g, and for material B at 30 days it was 33 +/- 27
mg/g.(ABSTRACT TRUNCATED AT 250 WORDS)
