title: Effects of different acids and etching times on the bond strength of glass fiber-reinforced composite root canal posts to composite core material.
abstract: OBJECTIVE
  To investigate the effects of different acids and etching times on the bond strength of glass fiber-reinforced composite (FRC) posts to composite core material.
  
  
  METHODS
  Twenty-six FRC posts (FRC Postec Plus) were randomly divided into 13 groups (each n = 2). One group received no surface treatment (control). The posts in the other groups were acid etched with 35% phosphoric acid and 5% and 9.6% hydrofluoric acid gel for four different etching times (30, 60, 120, and 180 seconds). A cylindric polytetrafluoroethylene mold was placed around the treated posts and filled with dual-cure composite core material (MultiCore Flow). All samples were light cured for 60 seconds. After 24 hours of water storage, the specimens were sectioned perpendicularly to the bonded interface under water cooling to obtain 2-mm post-and-core specimens. Eight specimens were made from each group. Push-out tests were performed at a crosshead speed of 0.5 mm/min using a universal testing machine. Data were analyzed by one-way ANOVA followed by the Tukey honestly significant difference test (alpha = .05).
  
  
  RESULTS
  The lowest bond strength was observed in the control group (12.51 megapascal [MPa]). No statistical significant difference was observed among group H5-120 (20.31 MPa), group H9-120 (20.55 MPa), or group P-180 (20.57 MPa) (P > .05). These groups demonstrated the highest bond strength values (P < .05).
  
  
  CONCLUSIONS
  For the FRC posts, all acid-etching procedures tested showed significantly increased bond strength when compared with the control group. Acid-etching with 5% hydrofluoric acid and 9.6% hydrofluoric acid for 2 minutes and with 35% phosphoric acid for 3 minutes (groups H5-120, H9-120, and P-180, respectively) demonstrated the highest bond strength values between the FRC post and composite core material. Although the bond strength was increased by prolonged acid etching, the microstructure of the FRC posts might have been damaged.
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Ondokuz Mayis University, Samsun, Turkey. auguler@omu.edu.tr
authors.forename: Ahmet Umut
authors.initials: AU
authors.lastname: Güler
authors.forename: Murat
authors.initials: M
authors.lastname: Kurt
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Duran
authors.forename: Altay
authors.initials: A
authors.lastname: Uludamar
authors.forename: Ozgur
authors.initials: O
authors.lastname: Inan
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003799:Dental Stress Analysis; D005898:Glass; D006858:Hydrofluoric Acid; D008689:Methacrylates; D010756:Phosphoric Acids; D011176:Post and Core Technique; D011897:Random Allocation; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D003188:Composite Resins; D008689:Methacrylates; C509715:MultiCore Flow; D010756:Phosphoric Acids; C009753:fiberglass; C030242:phosphoric acid; D006858:Hydrofluoric Acid