Cytotoxicity of intermaxillary orthodontic elastics of different colors: an in vitro study

Abstract

Objectives:Natural latex does not fall into the category of materials known to be entirely inoffensive. The purpose of this in vitro study was to test the hypothesis that there is no difference in the cytotoxicity between elastics of different colors and those from different manufacturers.Material and Methods:Different latex intraoral elastics of different colors (5/16 = 7.9 mm, mean load) were compared. The sample was divided into 7 groups of 24 elastics each: Group T (TP Orthodontics, natural latex elastics, control); Groups U1, U2, U3, U4, U5 and U6 (Uniden, natural latex elastics and colored elastics, namely, green, pink, yellow, red and purple, respectively). Cytotoxicity assays were performed by using cell culture medium containing epithelioid-type cells (Hep-2 line) derived from human laryngeal carcinoma. The cytotoxicity was evaluated by using the "dye-uptake" test, which was employed at two different moments (0 and 24 h). Data were compared by analysis of variance (ANOVA) and Tukey's test (p<0.05).Results:There was statistically significant difference (p<0.05) between Group T and all other groups (U1, U2, U3, U4, U5 and U6) at 0 and 24 h. No statistically significant difference (p<0.05) was found between Groups U1 and U5, U1 and U6, U2 and U3, U2 and U4, U2 and U5, U2 and U6, U3 and U4, U3 and U5, U3 and U6, U4 and U5, U4 and U6, and U5 and U6 at 0 and 24 h.Conclusions:The TP Orthodontics elastics promoted less cell lysis compared to the Uniden elastics regardless of their color.

Evaluation of the cytotoxicity of polyurethane and non-latex orthodontic chain elastics

“…Spectrophotometric essay allows rapid and reliable evidence for cell viability to be obtained based on the use of vital stain incorporated by viable cells [16,17]. In this study, we used neutral red dye as it is largely employed for identification of L-929 cell viability [23,24].…”

“…As sterilization is a prerequisite for cytotoxicity essays, ultraviolet radiation [16,17] was used in this study for 30 minutes for each elastic surface. It was observed that all elastics exhibited the same colour aspect following sterilization with UV light.…”

“…The superficial powder coating of the elastomeric ligatures was removed, in which, all elastics were washed for 15 seconds with current deionized water by using a Milli-Q purification system (Millipore, Bedford, MA, USA) and dried lightly with absorbent paper. Before testing all elastomeric ligatures were sterilized by exposure to ultraviolet light (Labconco, Kansas, Missouri, USA) for 30 minutes [16][17].…”

The effect of pH levels on nonlatex vs latex interarch elastics

“…Various studies 2,3,[5][6][7][8][9]3,14,[17][18][19][20] have attempted to establish the mechanical and environmental factors that contribute to the force decay of interarch elastics. However, a recent study 18 involving the effects of pH levels did not consider interarch elastics, nor the material modifications of the past 20 years.…”

“…1 Several properties of latex and nonlatex elastics have been evaluated, [2][3][4][5][6][7][8][9][10][11][12] some involving saliva or simulated saliva solutions. 2,[6][7][8][13][14][15][16][17] Few studies have investigated the effects of salivary pH levels on viscoelastic force relaxation of nonlatex interarch elastics.…”