The effect of cleaning and tooth whitening agents on the mechanical properties of two thermoplastic orthodontic retainer materials

Bowe, Denise Catherine (2016). The effect of cleaning and tooth whitening agents on the mechanical properties of two thermoplastic orthodontic retainer materials. University of Birmingham. M.Sc.

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Abstract

Thermoplastic retainers are removable appliances used to prevent teeth from moving from their corrected position after orthodontic treatment. Polyethylene and polypropylene and copolymers of these are used to fabricate thermoplastic retainers.
The aim of this study was to investigate the effect of cleaning agents, whitening gel and uniaxial tensile cyclic loading on the mechanical and thermal properties of thermoplastic orthodontic retainer materials.
The materials chosen for this investigation were: Essix ACE (polyethylene terephthalate) and Essix C+
(polypropylene), manufactured by Dentsply Raintree Essix, Florida, USA. Dumb-bell shaped specimens were fabricated using a thermal forming method for each test group from an acrylic template. Double-edge notched tension specimens were produced for tensile strength testing and un notched specimens for creep testing. Differential scanning calorimetry was used to understand the glass transition temperature and crystallinity of each material. For each characterisation both materials were initially tested dry and then following an immersion protocol in relevant cleaning and whitening solutions (distilled water, sodium hypochlorite, Retainer Brite and whitening gel).
Essix ACE demonstrated superior mechanical properties compared to Essix C+ in terms of tensile strength and creep. The use of cleaning agents or whitening gel in the short-term does not negatively affect the mechanical properties of either material.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):