Date of Award

Summer 2019

Document Type


Degree Name

Master of Science (MS)



First Advisor

Berzins, David

Second Advisor

Liu, Dawei

Third Advisor

Ahuja, Bhoomika


Different protocols appear in the literature with respect to heat-treating cobalt-chromium orthodontic wires. The objective was to determine the effect of variable heat-treatment time and method on the bending properties of CoCr wires. Two tempers of CoCr ‘Elgiloy’ wires (Rocky Mountain Orthodontics), blue (B) and yellow (Y), were heat-treated for different durations. The groups (n=20/group/temper) included: 1) as-received (control); 2) brush-flame; 3) 480oC for 5sec; 4) 480oC for 10min; 5) 480oC for 2hr; and 6) 480oC for 5hr. Wire segments were tested by a three-point bend test. Stiffness/flexural modulus, percent recovery, and force values at select deflections were statistically compared using ANOVA/Bonferroni post-hoc test (p<0.05). A T-test compared the different tempers. Longer heat-treatment (2hr/5hr) increased % recovery, flexural modulus, and force values when compared to the as-received counterparts. Heat treatment for 10 minutes resulted in intermediate increases. Using a brush-flame technique reduced elastic recovery and resulted in greater bending variability. Similar mechanical properties can be achieved in just 2 hours compared to the manufacturer recommended 5 hours of heat-treatment of Elgiloy wires. Ten minutes of heat-treatment, which may be more realistic in a busy orthodontic practice, can increase bending properties 50-75% compared to the 5-hour group. The brush-flame technique is not recommended due to inconsistent heating conditions resulting in varying bending properties.

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