Investigation Of Force Decay In Esthetic Composite Orthodontic Archwires

INVESTIGATION OF FORCE DECAY IN ESTHETIC COMPOSITE ORTHODONTIC ARCHWIRESJacob Spendlove, D.D.S.Marquette University, 2013Introduction:Fiber-reinforced composite archwires have been developed to increase the esthetics of orthodontic appliances. Because polymer containing composites typically exhibit time-dependent stress-strain behavior, deflected fiber-reinforced composite archwires may experience a decrease in force over time. The goal of this research was to determine if esthetic fiber-reinforced composite archwires can maintain continuous light forces without undergoing extreme amounts of force decay.Materials and Methods:Force decay was evaluated by comparing results of 3-point bending tests of nickel-titanium (NiTi) and fiber-reinforced composite archwires. Due to the impracticality of measuring force decay of a single archwire for 30 days, the following protocol was used: each segment was tested in 3-point bending using a universal testing machine to a maximum deflection of 3.1 mm; next, each segment was placed in a custom-made jig designed to deflect each segment either 1 or 2 mm for 30 days. Each segment was once again tested in 3-point bending to examine consistency of the bending profile. Paired t-tests were used to statistically compare pre- and post-deflection forces. A control group consisting of wires not subject to the 30 day constant deflection was tested to ensure that the initial testing did not alter the second 3-point bend test.Results:Statistically significant (pConclusions:The BioMers 1 mm deflection group demonstrated that fiber-reinforced composite archwires are able to deliver a consistent force after 30 days of deflection. However, the clinical applicability of these fiber-reinforced composite archwires may be limited as they are unable to sustain deflections of 2 mm without experiencing crazing and loss of force delivery.