title: Thickness and nanomechanical properties of protective layer formed by TiF4 varnish on enamel after erosion.
abstract: The layer formed by fluoride compounds on tooth surface is important to protect the underlying enamel from erosion. However, there is no investigation into the properties of protective layer formed by NaF and TiF4 varnishes on eroded enamel. This study aimed to evaluate the thickness, topography, nanohardness, and elastic modulus of the protective layer formed by NaF and TiF4 varnishes on enamel after erosion using nanoindentation and atomic force microscopy (AFM). Human enamel specimens were sorted into control, NaF, and TiF4 varnish groups (n = 10). The initial nanohardness and elastic modulus values were obtained and varnishes were applied to the enamel and submitted to erosive challenge (10 cycles: 5 s cola drink/5 s artificial saliva). Thereafter, nanohardness and elastic modulus were measured. Both topography and thickness were evaluated by AFM. The data were subjected to ANOVA, Tukey's test and Student's t test (α = 0.05). After erosion, TiF4 showed a thicker protective layer compared to the NaF group and nanohardness and elastic modulus values were significantly lower than those of the control group. It was not possible to measure nanohardness and elastic modulus in the NaF group due to the thin protective layer formed. AFM showed globular deposits, which completely covered the eroded surface in the TiF4 group. After erosive challenge, the protective layer formed by TiF4 varnish showed significant properties and it was thicker than the layer formed by NaF varnish.
authors.affiliation: Universidade Federal da Paraíba, Universidade Federal da Paraíba, João Pessoa PB , Brazil, Universidade Federal da Paraíba - UFPB, Postgraduation Program on Dentistry, João Pessoa, PB, Brazil.
authors.forename: Maria Isabel Dantas de
authors.initials: MI
authors.lastname: Medeiros
authors.affiliation: Universidade Federal da Paraíba, Universidade Federal da Paraíba, João Pessoa PB , Brazil, Universidade Federal da Paraíba - UFPB, Postgraduation Program on Dentistry, João Pessoa, PB, Brazil.
authors.forename: Hugo Lemes
authors.initials: HL
authors.lastname: Carlo
authors.affiliation: Universidade Federal de Campina Grande, Universidade Federal de Campina Grande, Department of Dentistry, Patos PB , Brazil, Universidade Federal de Campina Grande - UFCG, Department of Dentistry, Patos, PB, Brazil.
authors.forename: Rogério
authors.initials: R
authors.lastname: Lacerda-Santos
authors.affiliation: Universidade Federal da Paraíba, Universidade Federal da Paraíba, Department of Mechanical Tecnology, Tecnological Center, João Pessoa PB , Brazil, Universidade Federal da Paraíba - UFPB, Department of Mechanical Tecnology, Tecnological Center, João Pessoa, PB, Brazil.
authors.forename: Bruno Alessandro Guedes de
authors.initials: BA
authors.lastname: Lima
authors.affiliation: Universidade Federal da Paraíba, Universidade Federal da Paraíba, João Pessoa PB , Brazil, Universidade Federal da Paraíba - UFPB, Postgraduation Program on Dentistry, João Pessoa, PB, Brazil.
authors.forename: Frederico Barbosa de
authors.initials: FB
authors.lastname: Souza
authors.affiliation: Universidade Federal do Rio Grande do Sul, Universidade Federal do Rio Grande do Sul, School of Dentistry, Department of Pediatric Dentistry, Porto Alegre RS , Brazil, Universidade Federal do Rio Grande do Sul - UFRGS, School of Dentistry, Department of Pediatric Dentistry, Porto Alegre, RS, Brazil.
authors.forename: Jonas Almeida
authors.initials: JA
authors.lastname: Rodrigues
authors.affiliation: Universidade Federal da Paraíba, Universidade Federal da Paraíba, João Pessoa PB , Brazil, Universidade Federal da Paraíba - UFPB, Postgraduation Program on Dentistry, João Pessoa, PB, Brazil.
authors.forename: Fabiola Galbiatti de
authors.initials: FG
authors.lastname: Carvalho
mesh_terms: D000704:Analysis of Variance; D002253:Carbonated Beverages; D002327:Cariostatic Agents / Q000737:chemistry*; D003743:Dental Enamel / Q000187:drug effects*; D055119:Elastic Modulus; D005459:Fluorides / Q000737:chemistry*; D006245:Hardness Tests; D006801:Humans; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D012016:Reference Values; D015203:Reproducibility of Results; D012464:Saliva, Artificial / Q000737:chemistry; D012969:Sodium Fluoride / Q000737:chemistry*; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D014077:Tooth Erosion / Q000517:prevention & control*
chemical_list: D002327:Cariostatic Agents; D012464:Saliva, Artificial; D012969:Sodium Fluoride; D014025:Titanium; D005459:Fluorides; C032240:titanium tetrafluoride