Effect of surface contamination on adhesive bonding of cast pure titanium and Ti-6Al-4V alloy.
BACKGROUND
There is little information regarding bond strengths of resin cements to cast titanium surfaces contaminated by investment material.


OBJECTIVE
This study examined the effect of surface contamination on the shear bond strength of resin cements to cast titanium and Ti-6Al-4V alloy.


METHODS
Two types of disks were cast from commercially pure titanium (CP-Ti) and Ti-6Al-4V alloy ingots using an argon-arc pressure casting unit and a phosphate-bonded Al2 O3 /LiAlSiO6 investment. After casting, disks were subjected to 3 surface treatments: (1) cast surface sandblasted (50 microm-sized Al2 O3 ) for 30 seconds; (2) metal surface sanded with silicon-carbide paper (600 grit) after grinding the contaminated cast surface (approximately 200 microm in thickness); and (3) metal surface sandblasted for 30 seconds after treatment 2. Surface structures were examined after each treatment with SEM and optical microscopy. Each type of disk was then bonded with 2 types of luting materials. Bonded specimens were subjected to thermocycling for up to 50,000 cycles, and shear bond strengths were determined after 0 (baseline) and 50,000 thermocycles. Results were statistically analyzed with 3-way ANOVA (P <.05).


RESULTS
Microscopic observation of cast CP-Ti and Ti-6Al-4V exhibited noticeable structures on the cast surfaces apparently contaminated with investment material. However, there were no statistical differences (P >.05) in the bond strengths of both cements between contaminated (treatment 1) and uncontaminated surfaces (treatment 3) for both metals at baseline and after 50,000 thermocycles. The bond strength of specimens sanded with silicon-carbide paper (treatment 2) deteriorated dramatically after 50,000 thermocycles.


CONCLUSIONS
Contamination of the cast metal surfaces by elements of the investment during casting did not affect bond strengths of the luting materials to CP-Ti and Ti-6Al-4V.
Baylor College of Dentistry, Texas A&M University System, Dallas, Texas, USA.
I
I
Watanabe
E
E
Watanabe
K
K
Yoshida
T
T
Okabe
D000497:Alloys; D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D000704:Analysis of Variance; D001896:Boron Compounds / Q000737:chemistry; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D001840:Dental Bonding; D003734:Dental Casting Investment / Q000737:chemistry*; D006801:Humans; D018020:Lithium Compounds / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*
D000497:Alloys; D000538:Aluminum Silicates; D001896:Boron Compounds; D017554:Carbon Compounds, Inorganic; D003722:Dental Alloys; D003734:Dental Casting Investment; D018020:Lithium Compounds; D008689:Methacrylates; D008768:Methylmethacrylates; C093719:Panavia TPN-S; D010710:Phosphates; D019279:Resin Cements; D017655:Silicon Compounds; C031462:titanium alloy (TiAl6V4); C049495:Super-bond; D014025:Titanium; D000537:Aluminum Oxide; C022088:silicon carbide