title: The use of acetone to enhance the infiltration of HA nanoparticles into a demineralized dentin collagen matrix.
abstract: OBJECTIVE
  This study investigates the role of acetone, as a carrier for nano-hydroxyapatite (nano-HA) in solution, to enhance the infiltration of fully demineralized dentin with HA nanoparticles (NPs).
  
  
  METHODS
  Dentin specimens were fully demineralized and subsequently infiltrated with two types of water-based nano-HA solutions (one containing acetone and one without). Characterization of the dentin surfaces and nano-HA particles was performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface wettability and infiltration capacity of the nano-HA solutions were quantified by means of contact angle measurements and energy dispersive X-ray spectroscopy (EDS), respectively. Contact angle measurements were taken at baseline and repeated at regular intervals to assess the effect of acetone. The P and Ca levels of infiltrated dentin specimens were measured and compared to sound dentin and non-infiltrated controls.
  
  
  RESULTS
  The presence of acetone resulted in an eight-fold decrease in the contact angles of the nano-HA solutions recorded on the surface of demineralized dentin compared to nano-HA solutions without acetone (one-way ANOVA, p<0.05). Perfect wetting of the demineralized dentin surface was achieved 5min after the application of the nano-HA solution containing acetone. Infiltration of demineralized dentin with the nano-HA solution containing acetone restored the lost mineral content by 50%, whereas the mean mineralization values for P and Ca in dentin treated with the acetone-free nano-HA solution were less than 6%.
  
  
  CONCLUSIONS
  Acetone was shown to act as a vehicle to enhance the capacity to infiltrate demineralized dentin with HA NPs. The successful infiltration of dentin collagen with HA NPs provides a suitable scaffold, whereby the infiltrated HA NPs have the potential to act as seeds that may initiate heterogenous mineral growth when exposed to an appropriate mineral-rich environment.
authors.affiliation: School of Clinical Dentistry, University of Sheffield, Sheffield, UK. Electronic address: abessinis@hotmail.com.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Besinis
authors.affiliation: School of Clinical Dentistry, University of Sheffield, Sheffield, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: van Noort
authors.affiliation: School of Clinical Dentistry, University of Sheffield, Sheffield, UK.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Martin
mesh_terms: D000096:Acetone / Q000737:chemistry*; D003804:Dentin / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D008422:Materials Testing; D008854:Microscopy, Electron; D053758:Nanoparticles / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D017001:Tooth Demineralization; D017155:Wettability
chemical_list: C093073:Demineralized Dentin Matrix; D000096:Acetone; D017886:Durapatite
keywords: Adhesive resin monomer; Collagen infiltration; Contact angle measurements; Demineralization; Dentin bonding system; Electron microscopy; Nano-HA; Remineralization; Surface free energy; Wettability