Date of Award
5-1995
Document Type
Thesis - Restricted
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Virendra B. Dhuru
Second Advisor
Raymond A. Fournelle
Third Advisor
William G. Hubbard
Abstract
Orthodontic elastics have been used to generate tooth moving forces for nearly one hundred and fifty years. Currently used elastic materials in orthodontics are made either from natural rubber or synthetic polymeric materials. The former, referred to as elastic or latex (cis-polyisoprene) bands are available in various dimensions. The synthetic polymeric materials were supplied initially in the form of "modules" and subsequently as versatile "chains" and are commonly referred to as orthodontic elastomers or simply as elastomers (Figure 1). In the following text, the terms, elastomer, elastomeric chains or orthodontic elastomers refer specifically to the synthetic polymeric materials used in orthodontics to generate tooth moving forces.
Elastomers enjoy wide popularity in orthodontics. The orthodontist is particularly concerned with the force these elastomers can exert over the time period of their clinical use. To date, most of the research on these elastomeric chains has attempted to answer two questions. How much force can be generated by stretching these chains to distances that are required for tooth movement (e.g. canine retraction) and what is the rate of force-decay that occurs due to the stress relaxation in these orthodontic polymers. Both of these questions have direct clinical relevance and it is not surprising that most of the previous research has focused on these areas.
lnspite of their popularity, elastomeric chains have certain drawbacks. Their mechanical properties are time and temperature dependent. These elastomers swell and slowly hydrolyze on prolonged contact with water. Also, they are susceptible to aging due to the influence of light, thermal and chemical factors in their environment.
Little information is available on the viscoelastic properties of these materials. Evaluation of the basic material properties would complement the load extension and force-decay data that are presently available. Such additional information and characterization of these materials may be helpful in predicting the in vivo performance of these chains. Also, many different brands of elastomeric chains are available in the market. Some orthodontists have their own favorite brands of chains, those that work best for them. However, others use different brands interchangeably. It is unlikely that different brands would exert identical tooth moving forces.
Manufacturers provide limited information about the nature of these elastomers and surprisingly few instructions regarding their desirable storage conditions and shelf life. The chemical structure and the manufacturing processes of these chains largely remains proprietary information. The main chemical compound in the chains is, however, believed to be a polyurethane. It would be desirable to determine the possible relationships between the molecular structure, manufacturing processes and the mechanical properties of these materials.
The main goal of this investigation was to determine the viscoelastic and elastic properties of commercially available orthodontic elastomeric chains. A secondary goal was to obtain information from the manufacturers regarding the composition and recommendations for storage and use of these materials.
Recommended Citation
Huja, Sarandeep R., "Viscoelastic Properties of Orthodontic Elastomers" (1995). Master's Theses (1922-2009) Access restricted to Marquette Campus. 5635.
https://epublications.marquette.edu/theses/5635