title: Novel hydroxyapatite nanorods improve anti-caries efficacy of enamel infiltrants.
abstract: Enamel resin infiltrants are biomaterials able to treat enamel caries at early stages. Nevertheless, they cannot prevent further demineralization of mineral-depleted enamel. Therefore, the aim of this work was to synthesize and incorporate specific hydroxyapatite nanoparticles (HAps) into the resin infiltrant to overcome this issue.
  
  
  
  HAps were prepared using a hydrothermal method (0h, 2h and 5h). The crystallinity, crystallite size and morphology of the nanoparticles were characterized through XRD, FT-IR and TEM. HAps were then incorporated (10wt%) into a light-curing co-monomer resin blend (control) to create different resin-based enamel infiltrants (HAp-0h, HAp-2h and HAp-5h), whose degree of conversion (DC) was assessed by FT-IR. Enamel caries lesions were first artificially created in extracted human molars and infiltrated using the tested resin infiltrants. Specimens were submitted to pH-cycling to simulate recurrent caries. Knoop microhardness of resin-infiltrated underlying and surrounding enamel was analyzed before and after pH challenge.
  
  
  
  Whilst HAp-0h resulted amorphous, HAp-2h and HAp-5h presented nanorod morphology and higher crystallinity. Resin infiltration doped with HAp-2h and HAp-5h caused higher enamel resistance against demineralization compared to control HAp-free and HAp-0h infiltration. The inclusion of more crystalline HAp nanorods (HAp-2h and HAp-5h) increased significantly (p<0.05) the DC.
  
  
  
  Incorporation of more crystalline HAp nanorods into enamel resin infiltrants may be a feasible method to improve the overall performance in the prevention of recurrent demineralization (e.g. caries lesion) in resin-infiltrated enamel.
authors.affiliation: Group of Chemistry of Advanced Materials (GQMAT) - Department of Analytical Chemistry and Physic-chemistry, Federal University of Ceará - UFC, Campus do Pici, CP 12100, Zip Code 60451-970, Fortaleza, Brazil.
authors.forename: D M
authors.initials: DM
authors.lastname: Andrade Neto
authors.affiliation: Group of Chemistry of Advanced Materials (GQMAT) - Department of Analytical Chemistry and Physic-chemistry, Federal University of Ceará - UFC, Campus do Pici, CP 12100, Zip Code 60451-970, Fortaleza, Brazil.
authors.forename: E V
authors.initials: EV
authors.lastname: Carvalho
authors.affiliation: Post-Graduate Program in Dentistry - Department of Restorative Dentistry, Federal University of Ceará, Fortaleza, Brazil.
authors.forename: E A
authors.initials: EA
authors.lastname: Rodrigues
authors.affiliation: Post-Graduate Program in Dentistry - Department of Restorative Dentistry, Federal University of Ceará, Fortaleza, Brazil. Electronic address: victorpfeitosa@hotmail.com.
authors.forename: V P
authors.initials: VP
authors.lastname: Feitosa
authors.affiliation: Post-Graduate Program in Dentistry - Department of Restorative Dentistry, Federal University of Ceará, Fortaleza, Brazil; Dental Biomaterials - Departmento de Odontologia, Facultad de Ciencias de la Salud, CEU-Cardenal Herrera University, Alfara del Patriarca, 46115 Valencia, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Sauro
authors.affiliation: Dipartimento di Ingegneria dell'Innovazione, Università del Salento, Via Arnesano, 73100 Lecce, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Mele
authors.affiliation: CNR-IPCF UOS Pisa, Via G. Moruzzi 1 - 56124 Pisa, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Carbone
authors.affiliation: Group of Chemistry of Advanced Materials (GQMAT) - Department of Analytical Chemistry and Physic-chemistry, Federal University of Ceará - UFC, Campus do Pici, CP 12100, Zip Code 60451-970, Fortaleza, Brazil.
authors.forename: S E
authors.initials: SE
authors.lastname: Mazzetto
authors.affiliation: Post-Graduate Program in Dentistry - Department of Restorative Dentistry, Federal University of Ceará, Fortaleza, Brazil.
authors.forename: L K
authors.initials: LK
authors.lastname: Rodrigues
authors.affiliation: Group of Chemistry of Advanced Materials (GQMAT) - Department of Analytical Chemistry and Physic-chemistry, Federal University of Ceará - UFC, Campus do Pici, CP 12100, Zip Code 60451-970, Fortaleza, Brazil. Electronic address: fechine@ufc.br.
authors.forename: P B A
authors.initials: PB
authors.lastname: Fechine
mesh_terms: D055117:Curing Lights, Dental; D003743:Dental Enamel; D017886:Durapatite; D006801:Humans; D043942:Nanotubes; D019279:Resin Cements; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D019279:Resin Cements; D017886:Durapatite
keywords: Caries; Composite materials; Dimethacrylate; Nanotechnology