title: An in situ evaluation of the polymerization shrinkage, degree of conversion, and bond strength of resin cements used for luting fiber posts.
abstract: BACKGROUND
  The behavior and magnitude of the deformations that occur during polymerization and the behavior of the luting agents of glass fiber posts inside the root canal require quantification.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to investigate the in situ polymerization shrinkage, degree of conversion, and bond strength inside the root canal of resin cements used to lute fiber posts.
  
  
  METHODS
  Thirty maxillary canines were prepared to lute fiber posts. The teeth were randomly divided into 2 groups (n=15) according to the cementation system used, which included ARC, the conventional dual-polymerized resin cement RelyX ARC, and the U200 system, a self-adhesive resin cement, RelyX U200. Two fiber optic sensors with recorded Bragg gratings (FBG) were attached to each post before inserting the resin cement inside the root canal to measure the polymerization shrinkage (PS) of the cements in the cervical and apical root regions (με). Specimens were sectioned (into cervical and apical regions) to evaluate bond strength (BS) with a push-out test and degree of conversion (DC) with micro-Raman spectroscopy. Data were statistically analyzed with 2-way ANOVA and the Tukey honestly significant difference post hoc test (α=.05).
  
  
  RESULTS
  The ARC and U200 system showed similar PS values (-276.4 ±129.2 με and -252.1 ±119.2 με, respectively). DC values from ARC were higher (87.5 ±2.7%) than those of U200 (55.9 ±9.7%). The cervical region showed higher DC values (74.8 ±15.2%) and PS values (-381.6 ±53.0 με) than those of the apical region (68.5 ±20.1% and -146.9 ±43.5 με, respectively) for both of the resin cements. BS was only statistically different between the cervical and apical regions for ARC (P<.05).
  
  
  CONCLUSIONS
  The ARC system showed the highest PS and DC values compared with U200; and for both of the resin cements, the PS and DC values were higher at the cervical region than at the apical region of the canal root. BS was higher in the cervical region only for ARC.
authors.affiliation: Doctoral student, Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Brazil. Electronic address: capulidomora@hotmail.com.
authors.forename: Camilo Andrés
authors.initials: CA
authors.lastname: Pulido
authors.affiliation: Professor, Department of Electrical Engineering, Federal University of Technology, Paraná, Brazil.
authors.forename: Ana Paula Gebert
authors.initials: AP
authors.lastname: de Oliveira Franco
authors.affiliation: Professor, Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Brazil.
authors.forename: Giovana Mongruel
authors.initials: GM
authors.lastname: Gomes
authors.affiliation: Professor, Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Brazil.
authors.forename: Bruna Fortes
authors.initials: BF
authors.lastname: Bittencourt
authors.affiliation: Professor, Department of Electrical Engineering, Federal University of Technology, Paraná, Brazil.
authors.forename: Hypolito José
authors.initials: HJ
authors.lastname: Kalinowski
authors.affiliation: Professor, Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Brazil.
authors.forename: João Carlos
authors.initials: JC
authors.lastname: Gomes
authors.affiliation: Professor, Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Brazil.
authors.forename: Osnara Maria Mongruel
authors.initials: OM
authors.lastname: Gomes
mesh_terms: D001840:Dental Bonding / Q000379:methods* / Q000592:standards; D003738:Dental Cements / Q000627:therapeutic use*; D018772:Dental Marginal Adaptation; D003799:Dental Stress Analysis; D006801:Humans; D066298:In Vitro Techniques; D058105:Polymerization; D011176:Post and Core Technique; D019279:Resin Cements / Q000627:therapeutic use*
chemical_list: D003738:Dental Cements; D019279:Resin Cements