The influence of pH levels on mechanical and biological properties of nonlatex and latex elastics

Abstract

Objective: To evaluate the influence of pH levels on interarch elastics with regard to force decay and cytotoxicity. Materials and Methods: One nonlatex (NLAO) group and one latex (LAO) group were tested (n 5 10). Elastics were stretched to 25 mm and were held for 1, 6, 12, and 24 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. The cytotoxicity assay was performed using cell cultures (L929 mouse fibroblast cell line), which were subjected to the cell viability test with neutral red (''dye-uptake''). Force decay and cytotoxicity were assessed using analysis of variance, the Sidak method, and a Tukey's test. Results: The interactions between group, pH, and time showed no statistically significant differences (P 5 .29). When pH per time (P 5 .032) and group per time (P 5 .0009) were considered, these interactions showed statistically significant differences (P , .05). The pH did not interfere directly in the degradation results of the tested elastics. The cytotoxicity test showed that group LAO presented lower cell viability when compared with group NLAO over the course of the entire experiment. There was a gradual reduction in cell viability from 1 hour to 24 hours. A significant difference (P , .05) was found between the interactions group pH and the control group of cells, except between group NLAO at the time point of 1 hour at different pH values and at the time points of 6 and 12 hours with pH 5 (P . .05). Conclusions: No significant correlation between pH, force decay, and cytotoxicity was observed. (Angle Orthod. 2012;82:709-714.)

Synergic effect of salivary pH baselines and low pH intakes on the force relaxation of orthodontic latex elastics

“…They concluded that pH levels of 5 and 6 in the 24 h investigation were not significant contributors to the force relaxation of interarch elastics in comparison to pH of 7. [89]…”

“…Particularly, these properties are influenced by several factors related to the material such as loss of elasticity, amount of force decay, and composition of the elastics,[4] and also, the environmental factors such as composition of saliva, intraoral pH and temperature variations, food texture and pigments. [48910] A few studies have evaluated the effect of salivary pH and its changes on the force degradation of latex elastics. [811] Previous studies found no correlation between changes of salivary baseline pH and the force relaxation of elastic.…”

“…[48910] A few studies have evaluated the effect of salivary pH and its changes on the force degradation of latex elastics. [811] Previous studies found no correlation between changes of salivary baseline pH and the force relaxation of elastic. [89] The pH of the oral environment which is determined by pH of both saliva and dental plaque can affect these intraoral latex elastics.…”

“…[811] Previous studies found no correlation between changes of salivary baseline pH and the force relaxation of elastic. [89] The pH of the oral environment which is determined by pH of both saliva and dental plaque can affect these intraoral latex elastics. [12] Ferriter et al .…”

Do alcoholic beverages interfere in the force of orthodontic elastics?

“…However, they are not considered ideal materials due to the decline in force required for efficient tooth movement 11 . Several studies 6,7,[12][13][14] have been conducted with the purpose of investigating mechanical and environmental factors that contribute to the degradation of force in orthodontic elastics. Santos et al 2 , in a study conducted in 2007, reported that elastomeric chains exposed to piquant foods, humidity and high temperatures presented greater deterioration in force than those exposed to only water, which is in accordance with the findings of Evangelista et al 10 in 2007, who affirmed that factors such as chemical and salivary enzymes, and variations in temperature and pH, would be associated with relaxation and deformation of the polymer.…”