Effect of loading rate on bond strength.
The purpose of this study was to examine the effect of loading rate on the bond strength of brackets bonded to enamel. Forty premolars were used and brackets were bonded with a chemically cured or a light-cured adhesive, mounted on a testing machine, and debonded under shear stress at two loading velocities: a standard 1 mm/min, and a fast 200 mm/min which better approximates the actual jaw velocity during chewing. Bond strength results (N) were analyzed with two-way analysis of variance (loading rate, adhesive) (alpha = 0.05). An increased loading rate resulted in decreased bond strength, probably due to the induction of a stiff body response and elimination of the viscoelastic properties of the resin. The results indicated a similar effect on both chemically cured and light-cured adhesives, thus emphasizing the need for standardized test conditions in bond strength protocols. The implication of loads generated during chewing must be considered when estimating the long-term survival of the bond.
Eliades
Theodore
T
Biomaterials Laboratory, School of Dentistry, University of Athens, Athens, Greece. teliades@ath.forthnet.gr
Katsavrias
Elias
E
Zinelis
Spiros
S
Eliades
George
G
D000268:Adhesiveness; D001641:Bicuspid / Q000502:physiology*; D019245:Compressive Strength / Q000502:physiology; D001840:Dental Bonding / Q000295:instrumentation* / Q000379:methods*; D003799:Dental Stress Analysis / Q000379:methods*; D019544:Equipment Failure Analysis / Q000379:methods*; D006801:Humans; D066298:In Vitro Techniques; D016910:Orthodontic Brackets; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology*