Effect of surface treatments on the bond strength of glass ionomers to enamel.
OBJECTIVE
The objective of this study was to evaluate the effect of various surface treatments on the bond strength of several glass ionomers to enamel, and to examine the resulting bond interface.


METHODS
Ground bovine enamel specimens were divided into groups which were pretreated with one of the following: (1) no pretreatment, (2) Vitremer primer, (3) 10% polyacrylic acid or (4) 35% phosphoric acid. A conventional glass ionomer and two resin-modified glass ionomers (RMGI's) were bonded to the pretreated enamel surfaces, stored in water for 24h and shear bond strengths measured. RMGI's were tested as light-cured and self-cured materials. Transverse sections of similarly prepared samples were etched with phosphoric acid for 60s to partially remove enamel and expose the enamel/glass-ionomer interface. The interface morphology was examined by SEM.


RESULTS
Polyacrylic acid and phosphoric acid conditioning resulted in significantly increased bond strength to enamel for all three glass ionomer materials, compared to no pretreatment (p<0.01). Light-cured bond strengths were in most cases, significantly greater than when self-cured (p<0.01). Examination of the bonded interfaces revealed the presence of polymer tags in the enamel conditioned with polyacrylic acid and phosphoric acid.


CONCLUSIONS
Conditioners significantly improved the bond to enamel for the conventional glass ionomer and RMGI's that were examined in this study. Micromechanical bonding may play a role in the mechanism of bonding glass ionomer to enamel.
Glasspoole
Eileen A
EA
3M Health Care, St. Paul, MN, USA. eaglasspoole@mmm.com
Erickson
Robert L
RL
Davidson
Carel L
CL
D000134:Acid Etching, Dental; D000180:Acrylic Resins / Q000737:chemistry; D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008027:Light; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000180:Acrylic Resins; D003188:Composite Resins; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D010756:Phosphoric Acids; D019279:Resin Cements; D012117:Resins, Synthetic; C084550:Vitremer; D014867:Water; C084541:Fuji glass-ionomer lining cement; C006903:carbopol 940