title: Effects of a fluoride etchant and a phosphate primer on bonding of veneering composite to Ti-6Al-4V alloy for CAD/CAM restorations.
abstract: OBJECTIVE
  Titanium abutments and superstructures are commonly veneered or covered with esthetic materials. The present investigation was carried out to evaluate the effects of an experimental surface treatment using etchant and primer on bond strength between a resin composite and Ti-6Al-4V alloy.
  
  
  METHODS
  Disk-shaped Ti-6Al-4V alloy was machine milled, the surface was air abraded with alumina, and the alloy was chemically etched with 5 wt% ammonium hydrogen fluoride (F-etch) for 30s. A phosphate primer (MDP-primer) was applied to the bonding area, and then a resin composite, with or without milled-fiber resin composite (FRC), was veneered on the specimen. Shear bond strengths were determined after thermocycling for 20,000 cycles. Bond strength data were analyzed by means of ANOVA and a multiple comparison test (α=0.05). The surface of Ti-6Al-4V alloy was observed using a scanning electron microscope before and after the etching procedure.
  
  
  RESULTS
  No-FRC/F-etch/MDP-primer exhibited the highest bond strength (28.2 MPa), followed by No-FRC/No-etching/MDP-primer (24.2 MPa), FRC/F-etch/MDP-primer (19.9 MPa), FRC/No-etching/MDP-primer (17.8 MPa), No-FRC/No-etching/No-primer (13.6 MPa), while FRC/No-etching/No-primer (2.5 MPa) resulted in the lowest value. Microphotographs showed that numerous micro and nano pits were created on the Ti-6Al-4V alloy surface modified with F-etch.
  
  
  CONCLUSIONS
  The bond strength between Ti-6Al-4V alloy and the veneering resin composite was the highest when the alloy surface was modified with alumina blasting, fluoride etchant, and phosphate primer successively.
authors.affiliation: Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, Japan. yohsuke@nagasaki-u.ac.jp
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Taira
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Odatsu
authors.forename: Takashi
authors.initials: T
authors.lastname: Sawase
mesh_terms: D000497:Alloys; D017076:Computer-Aided Design; D001840:Dental Bonding; D003801:Dental Veneers; D005459:Fluorides / Q000494:pharmacology*; D010710:Phosphates / Q000494:pharmacology*; D014025:Titanium
chemical_list: D000497:Alloys; D010710:Phosphates; C031462:titanium alloy (TiAl6V4); D014025:Titanium; D005459:Fluorides