title: The role of spacer carbon chain in acidic functional monomers on the physicochemical properties of self-etch dental adhesives.
abstract: OBJECTIVE
  To evaluate the effects of acidic functional monomers with different hydrophilicity and spacer carbon chain length on the degree of conversion (DC), wettability (contact angle), water sorption (WS) and ultimate tensile strength (UTS) of experimental one-step self-etch adhesives (1-SEAs).
  
  
  METHODS
  A series of standard resin blends was prepared with each formulation containing 15mol% of each acidic monomer. The structural variations of the acidic monomers were MEP (spacer chain with 2 carbons), MDP (10-carbons), MDDP (12-carbons), MTEP (more hydrophilic polyether spacer) and CAP-P (intermediate hydrophilicity ester spacer). Dumbbell-shaped and disc specimens were prepared and tested for UTS and WS, respectively. DC was assessed by FTIR, while the wettability of each 1-SEA was evaluated on glass slides and flat dentine surfaces. Results were analysed with one-way ANOVA and Tukey's test (p<0.05).
  
  
  RESULTS
  The outcomes showed lower UTS for CAP-P, control blend and MEP than MTEP, MDDP and MDP (p<0.05). The degree of conversion was statistically similar for all resins (p=0.122). On dentine, the wettability was higher (lower contact angle) with the most hydrophilic monomer MTEP. Higher WS was attained using MTEP. Different lengths of the spacer chains did not result in different wettability and WS (p>0.05).
  
  
  CONCLUSIONS
  At similar molar percentage, different acidic functional monomers induced similar degree of conversion and different UTS when included in a 1-SEA. However, the inclusion of highly hydrophilic monomer may increase the wettability on dentine and the WS.
authors.affiliation: Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil; King's College London Dental Institute, London, United Kingdom. Electronic address: victorpfeitosa@hotmail.com.
authors.forename: Victor P
authors.initials: VP
authors.lastname: Feitosa
authors.affiliation: King's College London Dental Institute, London, United Kingdom; Biomaterials and Minimally Invasive Dentistry - Departamento de Odontologia, Facultad de Ciencias de la Salud, Universidad CEU-Cardenal Herrera, Valencia, Spain.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sauro
authors.affiliation: Materials Engineering School, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Fabricio A
authors.initials: FA
authors.lastname: Ogliari
authors.affiliation: School of Dental Medicine, University of Colorado Denver, Aurora, USA.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Stansbury
authors.affiliation: King's College London Dental Institute, London, United Kingdom.
authors.forename: Guy H
authors.initials: GH
authors.lastname: Carpenter
authors.affiliation: King's College London Dental Institute, London, United Kingdom.
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Watson
authors.affiliation: Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil.
authors.forename: Mário A
authors.initials: MA
authors.lastname: Sinhoreti
authors.affiliation: Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil.
authors.forename: Américo B
authors.initials: AB
authors.lastname: Correr
mesh_terms: D065966:Absorption, Physicochemical; D000143:Acids / Q000737:chemistry; D000327:Adsorption; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002208:Caproates / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D055598:Chemical Phenomena; D003188:Composite Resins / Q000737:chemistry*; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007783:Lactones / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D013314:Stress, Mechanical; D013718:Tensile Strength; D014867:Water / Q000737:chemistry; D017155:Wettability
chemical_list: D000143:Acids; D002208:Caproates; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D007783:Lactones; D008689:Methacrylates; D011109:Polymethacrylic Acids; D011140:Polyurethanes; C114321:methacryloxyethyl dihydrogen phosphate; D014867:Water; C029824:urethane dimethacrylate luting resin; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C121056:caprolactone; C005044:hydroxyethyl methacrylate; D002244:Carbon; C069749:methacryloyloxydecyl dihydrogen phosphate
keywords: Contact angle; Degree of conversion; Functional monomers; Self-etching adhesives; Ultimate tensile strength; Wettability