A Comparison of the Force Degradation of Marketed Latex Elastics in Varying Normal Resting pHs
thesisposted on 10.12.2012 by Michael B. Everson
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The objective of this study was to determine the amount of force degradation seen in 1/4", 4.5 ounce elastics, which are commonly used at the University of Illinois at Chicago orthodontic clinic for anterior-posterior correction, under different normal resting salivary pHs. The null hypothesis tested was that there was no difference in the percent of initial force regardless of pH or manufacturer over five timepoints. The two manufacturers tested were G&H and RMO and the size of the elastics tested were 1/4", 4.5 ounces. The elastics were stretched to 3x their diameter and the timepoints that were measured were initial, 0.5, 1, 4, 8, and 12 hours. The elastics were tested in three different pH levels to determine the percent of initial force remaining at each timepoint. The three pH levels tested were 5.60, 6.75, and 7.60. The elastics were stretched to 3x their diameter by having a block with pins separated 19.05mm apart. The blocks were submerged in an artificial saliva bath kept at 37 degrees Celsius. There were significant mean differences found for the pH of 5.60 when compared to the pH of 6.75 and the pH of 7.60 for RMO. There was a significant difference at the pH of 5.60 between the two manufacturers with RMO having a higher percent of initial force among the five timepoints. Within RMO, there was less force degradation in the artificial saliva at a pH of 5.60 when compared to the pH of 6.75 and the pH of 7.60.