In vitro study of structural and mechanical properties of latex and non-latex intermaxillary orthodontic elastics.

Abstract

We evaluated bacterial endotoxin adhesion, superficial micromorphology and mechanical properties of latex and non-latex intermaxillary orthodontic elastics. To quantify the adhered bacterial endotoxin, elastics were divided into 5groups: experimental (n = 12) latex and non-latex elastics, previously contaminated by an endotoxin solution, negative control (n = 6) latex and non-latex elastics without contamination, and positive control (n = 6) stainless steel specimens (metallic replicas), contaminated by an endotoxin solution. In parallel, the structural micromorphology (n = 6) and surface roughness of latex and non-latex intermaxillary orthodontic elastics were assessed using confocal laser microscopy. Force degradation(g) and deformation of the internal diameter change (mm) were also evaluated. Structural micromorphology, surface roughness (µm), force degradation(g) and internal diameter (mm) change were evaluated at time 0and after 24and 72 h in adeformation test. Data were analyzed by the Shapiro-Wilk, Kruskal-Wallis, Dunn, ANOVA and Bonferroni tests (α = 5%). Endotoxin adhered similarly to both types of elastics withscores of 3 (> 1.0 EU/mL). The surface microstructure of both types of elastics showed irregularities and porosities at all times. Initially, the latex elastics had ahigher surface roughness (p < 0.001) than the non-latex ones. After 24 h loading, surface roughness of the latex elastics was significantly reduced (p < 0.001), while after 72 h, the values were similar for both types (p > 0.05). The non-latex elastics had significantly higher force generation values (p < 0.05) at 0, 24and 72 h compared with the latex elastics, although there was asignificant reduction (p < 0.001) in force over time for both elastics. Despite similar initial values, non-latex elastics had asignificantly larger internal diameter (p < 0.001) after the loading periods of 24and 72 h compared with the latex elastics. Both elastics showed high affinity with endotoxin and microstructural irregularities of their surface. The non-latex elastics generated higher force values but demonstrated greater deformation of the internal diameter after loading.