title: Polypropylene glycol phosphate methacrylate as an alternative acid-functional monomer on self-etching adhesives.
abstract: OBJECTIVE
  The aim of this study was to synthesize an alternative acidic monomer (polypropylene glycol phosphate methacrylate--Poly-P) to constitute experimental two-step self-etch adhesive systems and also to evaluate its influence on the pH and microshear bond strength (μSBS) to enamel.
  
  
  METHODS
  Primers containing Poly-P (10, 15, 30 or 50wt.%), HEMA, ethanol, and water were prepared and allocated in subgroups according to a buffered or non-buffered pH. One experimental control and one commercial (Clearfill™ SE Bond) references were used. μSBS protocol was performed at human enamel, followed by mechanical testing. Scanning electron microscopy (SEM) was performed after each primer application. Data was analysed by one-way Kruskal-Wallis and Student-Newman-Keuls tests (p<0.05) and by linear regression predictive models.
  
  
  RESULTS
  As greater the Poly-P content, the lower the primer's pH. Buffered groups showed lower μSBS values than non-buffered groups. Groups with Poly-P content equal or higher than 30wt.% showed similar μSBS results when compared to the controls. SEM images demonstrated that primers with high Poly-P content etched enamel with prisms exposure.
  
  
  CONCLUSIONS
  The pH of the primer was directly influenced by the concentration of acidic monomer, which directly affected the adhesion to enamel. Both the acidity and the type of acid-functional monomer present in the adhesive influenced the bond strength results.
  
  
  CONCLUSIONS
  Poly-P synthesis was easy and effective, and considering the good bond strength results obtained, this acid-functional monomer may be potentially used in the formulation of self-etch dental adhesive systems.
authors.affiliation: Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil. Electronic address: eliseumunchow@gmail.com.
authors.forename: Eliseu Aldrighi
authors.initials: EA
authors.lastname: Münchow
authors.affiliation: Developmental and Control Center of Biomaterials, Federal University of Pelotas, Pelotas, RS, Brazil; Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: Adriana Fernandes
authors.initials: AF
authors.lastname: da Silva
authors.affiliation: Developmental and Control Center of Biomaterials, Federal University of Pelotas, Pelotas, RS, Brazil; Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: Giana
authors.initials: G
authors.lastname: da Silveira Lima
authors.affiliation: Developmental and Control Center of Biomaterials, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: Tais
authors.initials: T
authors.lastname: Wulff
authors.affiliation: Developmental and Control Center of Biomaterials, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: Marília
authors.initials: M
authors.lastname: Barbosa
authors.affiliation: Developmental and Control Center of Biomaterials, Federal University of Pelotas, Pelotas, RS, Brazil; Department of Polymeric Materials, School of Materials Engineering, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: Fabrício Aulo
authors.initials: FA
authors.lastname: Ogliari
authors.affiliation: Developmental and Control Center of Biomaterials, Federal University of Pelotas, Pelotas, RS, Brazil; Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: Evandro
authors.initials: E
authors.lastname: Piva
mesh_terms: D001840:Dental Bonding / Q000009:adverse effects / Q000379:methods*; D003738:Dental Cements / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use*; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects*; D003799:Dental Stress Analysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008689:Methacrylates / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use*; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use*; D033081:Shear Strength; D013499:Surface Properties
chemical_list: D003738:Dental Cements; D008689:Methacrylates; D010710:Phosphates; C508958:ethylene glycol methacrylate phosphate
keywords: Acidic monomer; Dental adhesive; Micro-shear bond strength; Scanning electron microscopy; Self-etching; pH