Shear bond strengths attained in vitro with light-cured glass ionomers vs composite adhesives in bonding ceramic brackets to metal or porcelain.
OBJECTIVE
The aim of this in vitro study was to evaluate whether light-cured resin-modified glass ionomers provide sufficient bond strength for bonding ceramic brackets to metal and porcelain. In addition, the effect of mechanically retentive vs. silanized bracket bases on shear bond strength was investigated.


METHODS
Flat specimens made from amalgam, a precious metal alloy, or ceramic were air-abraded with Al2O3 for 3 s and subsequently bonded with either Transcend 6000 or Fascination ceramic brackets. Alternatively, 20 porcelain specimens were treated with 9.6% HF for 2 min. Fuji Ortho LC and Photac Bond (light-cured glass ionomer cements [GIC]) served as adhesives. Two composite adhesives (Concise orthodontic and Transbond) in combination with various conditioners formed the control groups. After water storage for 24 hours, the shear bond strengths of all specimens were determined.


RESULTS
Taking 10 MPa as a clinically sufficient bond strength, both resin-modified GICs produced a reliable retention of Transcend 6000 brackets on ceramic and amalgam, while the silanized Fascination brackets yielded a lower shear bond strength. On the precious metal alloy, only Fuji Ortho LC showed adequate strength. Various composite-conditioner combinations produced higher maximum bond strengths than the GICs. The location of bond failure varied considerably, and with most adhesives, bracket fractures occurred occasionally under shear stress.


CONCLUSIONS
The investigated light-cured GICs provide sufficient strength for bonding ceramic brackets, but in terms of bond failure site and bracket fracture, they provide no advantage over composite adhesives.
Jost-Brinkmann
P G
PG
Department of Orthodontics and Dentofacial Orthopedics, Humboldt-University Berlin (Charité), Augustenburger Platz 1, D-13353 Berlin.
Böhme
A
A
D002516:Ceramics; D003723:Dental Amalgam; D001840:Dental Bonding; D003776:Dental Porcelain; D005899:Glass Ionomer Cements; D006047:Gold Alloys; D008422:Materials Testing; D016910:Orthodontic Brackets; D019279:Resin Cements; D012821:Silanes; D013718:Tensile Strength
D005899:Glass Ionomer Cements; D006047:Gold Alloys; D019279:Resin Cements; D012821:Silanes; D003776:Dental Porcelain; D003723:Dental Amalgam