title: Effect of addition of nano-hydroxyapatite on physico-chemical and antibiofilm properties of calcium silicate cements.
abstract: OBJECTIVE
  Mineral Trioxide Aggregate (MTA) is a calcium silicate cement composed of Portland cement (PC) and bismuth oxide. Hydroxyapatite has been incorporated to enhance mechanical and biological properties of dental materials. This study evaluated physicochemical and mechanical properties and antibiofilm activity of MTA and PC associated with zirconium oxide (ZrO2) and hydroxyapatite nanoparticles (HAn).
  
  
  METHODS
  White MTA (Angelus, Brazil); PC (70%)+ZrO2 (30%); PC (60%)+ZrO2 (30%)+HAn (10%); PC (50%)+ZrO2 (30%)+HAn (20%) were evaluated. The pH was assessed by a digital pH-meter and solubility by mass loss. Setting time was evaluated by using Gilmore needles. Compressive strength was analyzed by mechanical test. Samples were radiographed alongside an aluminum step wedge to evaluate radiopacity. For the antibiofilm evaluation, materials were placed in direct contact with E. faecalis biofilm induced on dentine blocks. The number of colony-forming units (CFU mL-1) in the remaining biolfilm was evaluated. The results were submitted to ANOVA and the Tukey test, with 5% significance.
  
  
  RESULTS
  There was no difference in pH levels of PC+ZrO2, PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p>0.05) and these cements presented higher pH levels than MTA (p<0.05). The highest solubility was observed in PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p<0.05). MTA had the shortest initial setting time (p<0.05). All the materials showed radiopacity higher than 3 mmAl. PC+ZrO2 and MTA had the highest compressive strength (p<0.05). Materials did not completely neutralize the bacterial biofilm, but the association with HAn provided greater bacterial reduction than MTA and PC+ZrO2 (p<0.05) after the post-manipulation period of 2 days.
  
  
  CONCLUSIONS
  The addition of HAn to PC associated with ZrO2 harmed the compressive strength and solubility. On the other hand, HAn did not change the pH and the initial setting time, but improved the radiopacity (HAn 10%), the final setting time and the E. faecalis antibiofilm activity of the cement.
authors.affiliation: - Universidade Estadual Paulista, Faculdade de Odontologia de Araraquara, Departamento de Odontologia Restauradora, Araraquara, SP, Brasil.
authors.forename: Juliane Maria
authors.initials: JM
authors.lastname: Guerreiro-Tanomaru
authors.affiliation: - Universidade Estadual Paulista, Faculdade de Odontologia de Araraquara, Departamento de Odontologia Restauradora, Araraquara, SP, Brasil.
authors.forename: Fernando Antonio
authors.initials: FA
authors.lastname: Vázquez-García
authors.affiliation: - Universidade Estadual Paulista, Faculdade de Odontologia de Araraquara, Departamento de Odontologia Restauradora, Araraquara, SP, Brasil.
authors.forename: Roberta
authors.initials: R
authors.lastname: Bosso-Martelo
authors.affiliation: - Universidade de São Paulo, Instituto de Física, São Carlos, SP, Brasil.
authors.forename: Maria Inês Basso
authors.initials: MI
authors.lastname: Bernardi
authors.affiliation: - Universidade Estadual Paulista, Faculdade de Odontologia de Araraquara, Departamento de Odontologia Restauradora, Araraquara, SP, Brasil.
authors.forename: Gisele
authors.initials: G
authors.lastname: Faria
authors.affiliation: - Universidade Estadual Paulista, Faculdade de Odontologia de Araraquara, Departamento de Odontologia Restauradora, Araraquara, SP, Brasil.
authors.forename: Mario
authors.initials: M
authors.lastname: Tanomaru
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry* / Q000494:pharmacology; D000704:Analysis of Variance; D018441:Biofilms / Q000187:drug effects*; D001729:Bismuth / Q000737:chemistry / Q000494:pharmacology; D017610:Calcium Compounds / Q000737:chemistry* / Q000494:pharmacology; D015169:Colony Count, Microbial; D019245:Compressive Strength; D003738:Dental Cements / Q000737:chemistry / Q000494:pharmacology; D004338:Drug Combinations; D017886:Durapatite / Q000737:chemistry* / Q000494:pharmacology; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000254:growth & development; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D053758:Nanoparticles / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry* / Q000494:pharmacology; D017640:Silicates / Q000737:chemistry* / Q000494:pharmacology; D012995:Solubility; D013997:Time Factors; D015040:Zirconium / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D003738:Dental Cements; D004338:Drug Combinations; D010087:Oxides; D017640:Silicates; C086631:mineral trioxide aggregate; D017886:Durapatite; C033301:bismuth oxide; D015040:Zirconium; C028541:zirconium oxide; C031293:calcium silicate; D001729:Bismuth