title: Nano-hydroxyapatite could Compensate the Adverse Effect of soft carbonated Drinks on Enamel.
abstract: BACKGROUND
  Since one of the most important disadvantages of soft drinks includes their adverse effect on mineral content of enamel because of their low pH, this study examined the microhardness of enamel before and after exposure to a soft drink containing different concentrations of nano-hydroxyapatite (nano-HA) as an additive.
  
  
  METHODS
  Sixty caries free human premolars were mounted in epoxy resin. After polishing, the baseline micro-hardness was recorded three times for each specimen using a Vickers indenter at 50 gm load. Subsequently, the samples were divided into six groups, which were treated for 5 minutes at 9°C by a cola-based drink contacting 0, 0.5, 1, 5, and 10 wt.% of nano-HA while the control group was immersed in artificial saliva. Ultimately, the final microhardness was assessed three times again for each specimen.
  
  
  RESULTS
  Paired t-test showed that in groups containing 0 and 0.5 wt.% of nano-HA, the microhardness was significantly reduced after treatment protocol (p = 0.00 and 0.01 respectively). Whereas in the other groups the microhardness was not significantly changed after treatment (p > 0.05).
  
  
  CONCLUSIONS
  Pure cola-based drink has a pronounced adverse effect on enamel microhardness, while admixing it with nano-HA could act as a protective factor.
  
  
  CONCLUSIONS
  Although soft beverages are hazardous to tooth structure, some additives could compensate their adverse effect.
authors.affiliation: Department of Operative Dentistry, Shahed Dental School Shahed University, Tehran, Islamic Republic of Iran.
authors.forename: Mohammad B
authors.initials: MB
authors.lastname: Rezvani
authors.affiliation: Department of Operative Dentistry, Shahed Dental School Shahed University, Tehran, Islamic Republic of Iran.
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Rouhollahi
authors.affiliation: Department of Operative Dentistry, Isfahan Dental School Isfahan University of Medical Science, Isfahan, Islamic Republic of Iran.
authors.forename: Fahimeh
authors.initials: F
authors.lastname: Andalib
authors.affiliation: Assistant Professor, Oral and Dental Disease Research Center, Kerman University of Medical Science, Kerman, Islamic Republic of Iran, Phone: +983432126024, e-mail: f_hamzeh@kmu.ac.ir and faeze.hamze@gmail.com.
authors.forename: Faeze
authors.initials: F
authors.lastname: Hamze
mesh_terms: D002253:Carbonated Beverages / Q000009:adverse effects*; D003743:Dental Enamel / Q000187:drug effects; D017886:Durapatite / Q000008:administration & dosage*; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures / Q000008:administration & dosage*; D014077:Tooth Erosion / Q000209:etiology / Q000517:prevention & control*
chemical_list: D017886:Durapatite
keywords: Acidic soft drink; Cola; Enamel; Erosion; Hydroxyapatite; Nano-particle; Remineralization; Surface hardness.