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Abstract

The study focused on changes in elasticity that accompany water storage of a synthetic orthodontic elastomer. We plotted loading and unloading curves to permit the direct measurement of instantaneous elastic recovery (IER) and permanent set (PS) and the calculation of delayed recovery (DR). We obtained baseline data by testing dry as-received material. Comparable tests were performed on material that had been stored in water at 37°C for one, seven, 14, 42, and 70 days. Gas chromatography-mass spectrometry was used for analysis of organic substances leached from the elastomer by water. A two-way ANOVA revealed that extension distance and water storage duration affected load requirement, IER, PS, and DR. The presence of leachable organic substances in 14-, 42-, and 70-day storage water was evidence of time-dependent matrix decomposition. Findings from tests of elastic performance and analysis of specimen storage water indicate that exposure of the elastomer to water leads first to weakening of noncovalent forces and subsequently to degradation.

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References

Andreasen, G.F. and Bishara, S.E. (1970): Comparison of Alastik Chains with Elastics Involved with Intra-Arch Molar to Molar Forces, Angle Orthod 40:151-158.

Bishara, S.E. and Andreasen, G.F. (1970): A Comparison of Time Related Forces Between Plastic Alastiks and Latex Elastics, Angle Orthod 40:319-328.

Brantley, W.A. ; Salander, A. ; Myers, C.L. ; and Winders, R.V. (1979): Effects of Prestretching on Force Degradation Characteristics of Plastic Modules, Angle Orthod 49:37-43.

De Genova, D.C. ; McInnes-Ledoux, P. ; Weinberg, R. ; and Shaye, R. (1985): Force Degradation of Orthodontic Elastomeric Chains-A Product Comparison Study, Am J Orthod 87:377-384.

Hershey, H.G. and Reynolds, W.G. (1975): The Plastic Module as an Orthodontic Tooth-moving Mechanism, Am J Orthod 67:554-562.

Kovatch, J.S. ; Lautenschlager, E.P. ; Apfel, D.A. ; and Keller, J.G. (1976): Load-Extension-Time Behavior of Orthodontic Alastiks , J Dent Res 55:783-786.

Magnus, G. ; Dunleavy, R.A. ; and Critchfield, E.F. (1966): Stability of Urethane Elastomers in Water, Dry Air and Moist Air Environments, Rubber Chem and Tech 39:1328-1333.

Phua, S.K. ; Castillo, E. ; Anderson, J.M. ; and Hiltner, A. (1987): Biodegradation of a Polyurethane in vitro, J Biomed Mater Res 21:231-246.

Pigott, K.A. (1969): Polyurethanes. In: Encyclopedia of Polymer Science and Technology, Vol. 2, N.M. Bikales , Ed., New York: John Wiley and Sons, Inc., pp. 506-563.

10.

Ryhage, R. and Stenhagen, E. (1963): Mass Spectromctry of Long-Chain Esters. In: Mass Spectrometry of Organic Ions, F.W. McLafferty , Ed., New York: Academic Press, pp. 446-448.

11.

Schollenberger, C.S. and Stewart, F.D. (1971): Thermoplastic Polyurethane Hydrolysis Stability , J Elastoplast 3 :28-56.

12.

United States Atomic Energy Commission (1974 ): Mass Spectra of Compounds of Biological Interest, Vol. 2, Part 1, Spectra, S.P. Markey, W.G. Urban , and S.P. Levine , Eds., Oak Ridge, TN: U.S. Atomic Energy Commission, pp. 131, 132, 321, 423, 424.

13.

Young, J. and Sandrik, J.L. (1979): The Influence of Preloading on Stress Relaxation of Orthodontic Elastic Polymers, Angle Orthod 49:104-109.

Observations on the Elastic Behavior of a Synthetic Orthodontic Elastomer

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