title: Latex and nonlatex orthodontic elastics: In vitro and in vivo evaluations of tissue compatibility and surface structure.
abstract: OBJECTIVE
  To test the null hypothesis that there is no difference between latex and nonlatex orthodontic elastics with respect to tissue compatibility and surface structure.
  
  
  METHODS
  Latex and nonlatex elastics were implanted in the subcutaneous connective tissue of 45 Wistar rats. In the control groups, no material was implanted (sham). After 24 hours, 3, 7, 14, and 21 days, the animals were euthanized; tissue samples were processed and analyzed by descriptive and semi-quantitative microscopic analysis and quantification of plasma extravasation. The surface structure of elastics was evaluated by scanning electron microscopy (SEM). The results were analyzed by analysis of variance (ANOVA), Tukey test and Kruskal-Wallis test at 5% significance level.
  
  
  RESULTS
  Peri-implant plasma extravasation was significantly higher (P < .05) in the animals that received latex elastics compared with those with nonlatex elastics and those that were control animals. The microscopic analysis revealed a more intense inflammatory infiltrate in the initial periods without statistically significant difference (P > .05) between the experimental and control groups. The SEM analysis revealed that the latex elastics presented microspheres and porosities, while the nonlatex elastics exhibited crystals on their surface and absence of porosities.
  
  
  CONCLUSIONS
  The null hypothesis was rejected since the latex elastics were more irritating to the connective tissue than the nonlatex elastics in the initial periods and presented a more porous surface.
authors.affiliation: a  Associate Professor, Department of Integrated Pediatric Dentistry, School of Dentistry, University of Barcelona, Barcelona, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Martínez-Colomer
authors.affiliation: a  Associate Professor, Department of Integrated Pediatric Dentistry, School of Dentistry, University of Barcelona, Barcelona, Spain.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Gaton-Hernández
authors.affiliation: b  Professor, Department of Pediatric Clinics, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Fábio Lourenço
authors.initials: FL
authors.lastname: Romano
authors.affiliation: c  Associate Professor, Department of Pediatric Clinics, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Andiara
authors.initials: A
authors.lastname: De Rossi
authors.affiliation: d  Professor, Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Sandra Yasuyo
authors.initials: SY
authors.lastname: Fukada
authors.affiliation: e  Full Professor and Chairman, Department of Pediatric Clinic, School of Dentistry of Ribeirão Preto, University of São Paulo, SP, Brazil.
authors.forename: Paulo
authors.initials: P
authors.lastname: Nelson-Filho
authors.affiliation: f  Full Professor, Department of Stomatology, Bauru School of Dentistry, University of São Paulo, SP, Brazil.
authors.forename: Alberto
authors.initials: A
authors.lastname: Consolaro
authors.affiliation: c  Associate Professor, Department of Pediatric Clinics, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Raquel Assed Bezerra
authors.initials: RA
authors.lastname: Silva
authors.affiliation: g  Full Professor, Department of Pediatric Clinic, School of Dentistry of Ribeirão Preto, University of São Paulo, SP, Brazil.
authors.forename: Lea Assed Bezerra
authors.initials: LA
authors.lastname: Silva
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001672:Biocompatible Materials; D003116:Color; D003470:Culture Media; D007840:Latex; D008422:Materials Testing; D009967:Orthodontic Appliances; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001672:Biocompatible Materials; D003470:Culture Media; D007840:Latex
keywords: Inflammatory response; Latex; Nonlatex; Orthodontic elastics; SEM