Influence of cross-head speed in orthodontic bond strength testing.
OBJECTIVE
The aim of this study was to investigate the influence of cross-head speed on debonding force of orthodontic brackets.


METHODS
One hundred and twenty extracted permanent bovine mandibular incisors were randomly divided into 4 groups of 30 specimens each. Teeth were bonded with stainless steel orthodontic brackets. Enamel surfaces were etched with 37% phosphoric acid for 30 seconds and bonded with a composite adhesive. Debonding force measurements were performed with a universal testing machine Zwicki Z 2.5 (Zwick, Germany). Cross-head speeds of the four groups were: 0.1 mm s-1 (group A), 0.5 mm s-1 (group B), 1.0 mm s-1 (group C), 5.0 mm s-1 (group D).


RESULTS
Mean debonding force measurements were as follows: 215.35 (39.09) N (group A), 231.79 (48.62) N (group B), 236.64 (39.26) N (group C), 224.95 (34.67) N (group D). Analysis of variance indicated that there were no significant differences in debonding forces between the groups investigated. The adhesive remnant index showed a median value of 2.0 for all groups.


CONCLUSIONS
Cross-head speed variation between 0.1 and 5 mm min-1 does not seem to influence debonding force measurements or failure mode of brackets bonded to enamel with a composite adhesive.
Klocke
Arndt
A
Department of Orthodontics, University Hospital Hamburg-Eppendorf, ZZMK, Pav. O 53, Martinistr. 52, D-20246 Hamburg, Germany. klocke@uke.uni-hamburg.de
Kahl-Nieke
Bärbel
B
D000134:Acid Etching, Dental; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure; D003799:Dental Stress Analysis / Q000295:instrumentation / Q000379:methods*; D008422:Materials Testing; D016910:Orthodontic Brackets; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
D003188:Composite Resins; D019279:Resin Cements; D013193:Stainless Steel