The effect of pH levels on nonlatex vs latex interarch elastics

To evaluate the force decay characteristics of nonlatex vs latex interarch elastics within the normal range of salivary pH levels. Two nonlatex groups and one latex quasi-control group were tested. Elastics were stretched to 15 mm and were held for 10 seconds (baseline), 4 hours, 8 hours, and 12 hours in artificial saliva solutions with pH levels of 5.0, 6.0, and 7.5. Force magnitudes were measured at 25 mm of activation. Each specimen was used once. Measurements were assessed using three-way analysis of variance (ANOVA). The three-way interaction between group, pH, and time was not significant (P = .13); the group-by-pH interaction also was not significant (P = .70). However, pH-by-time (P = .0179) and group-by-time (P = .0001) interactions were significant. American Orthodontics nonlatex generated significantly higher loads than Auradonics nonlatex. American Orthodontics nonlatex produced significantly higher forces than American Orthodontics latex at 4, 8, and 12 hours, but not at 10 seconds. American Orthodontics latex was significantly stronger than Auradonics nonlatex at 10 seconds, but not at 4, 8, and 12 hours. No clinically significant correlation between pH and force decay was observed.