Effect of short curing times with a high-intensity light-emitting diode or high-power halogen on shear bond strength of metal brackets before and after thermocycling.
OBJECTIVE
To test the hypothesis that short curing times using a high-intensity light-emitting diode (LED) or high-power halogen are not associated with compromised shear bond strength (SBS) of metal brackets before and after thermocycling.


METHODS
Two hundred forty extracted human premolar teeth were divided into six groups of 40 each. Metal brackets were bonded using a light-cured composite (Transbond XT). In group 1 a conventional halogen light (Hilux) was used for 40 seconds. In groups 2, 3, and 4 a high-power halogen light (Swiss Master) was used for 2, 3, and 6 seconds, respectively. In groups 5 and 6 a high-intensity LED (Bluephase) was used for 10 and 20 seconds, respectively. After bonding, half of the specimens in each group were thermocycled, and all specimens were tested for SBS. After debonding, the bracket bases and the enamel surfaces were scored according to the Adhesive Remnant Index.


RESULTS
Two-way analysis of variance detected significant differences in SBS values with respect to curing method (type of light-curing unit and curing time) (P  =  .0001) and thermocycling (P  =  .01). Tukey post hoc analysis showed that with or without thermocycling the mean SBS values of groups 1, 4, 5, and 6 were not significantly different, whereas group 2 showed the lowest SBS values. The predominant failure site for groups 2 and 3 was between the bracket and the adhesive and for groups 4, 5, 6 it was at the tooth/adhesive interface.


CONCLUSIONS
Curing time can be reduced to 6 seconds with high-power halogen light and to 10 seconds with high-intensity LED without compromising in vitro SBS of metal brackets.
Department of Orthodontics, School of Dentistry, University of Marmara, Istanbul, Turkey.
Erion
E
Cerekja
Banu
B
Cakirer
D000704:Analysis of Variance; D001641:Bicuspid; D016009:Chi-Square Distribution; D055117:Curing Lights, Dental; D001840:Dental Bonding; D003799:Dental Stress Analysis; D006219:Halogens; D006358:Hot Temperature; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000528:radiation effects; D012666:Semiconductors; D033081:Shear Strength; D018709:Statistics, Nonparametric; D013997:Time Factors
D006219:Halogens; D019279:Resin Cements
Dent Mater. 2003 Sep;19(6):531-41
12837402
J Dent. 2006 Aug;34(7):498-502
16386827
Biomaterials. 2005 Nov;26(33):6449-59
15949841
Br Dent J. 1999 Apr 24;186(8):388-91
10365460
Biomaterials. 2000 Jul;21(13):1379-85
10850932
Oper Dent. 1998 Mar-Apr;23(2):50-4
9573788
Eur J Orthod. 2006 Feb;28(1):78-82
16199410
Am J Orthod Dentofacial Orthop. 2003 Jan;123(1):21-4
12532058
J Appl Oral Sci. 2007 Oct;15(5):412-5
19089170
Angle Orthod. 2004 Apr;74(2):259-63
15132454
Eur J Orthod. 2004 Oct;26(5):535-44
15536843
Am J Orthod Dentofacial Orthop. 2008 May;133(5):716-20
18456145
Am J Orthod Dentofacial Orthop. 2005 Dec;128(6):749-54
16360916
Angle Orthod. 2003 Aug;73(4):431-5
12940564
J Am Dent Assoc. 2004 Apr;135(4):461-3
15127869
Angle Orthod. 2005 Sep;75(5):854-7
16283816
Am J Orthod Dentofacial Orthop. 1998 Mar;113(3):271-5
9517717
Am J Orthod Dentofacial Orthop. 2005 Dec;128(6):744-8
16360915
J Dent Res. 2005 Feb;84(2):118-32
15668328
Am J Orthod Dentofacial Orthop. 2008 Oct;134(4):543-7
18929272
Am J Dent. 1998 Feb;11(1):17-22
9823081
Am J Orthod Dentofacial Orthop. 1998 Jul;114(1):80-7
9674685
Am J Orthod. 1984 Apr;85(4):333-40
6231863
Am J Orthod Dentofacial Orthop. 2004 Mar;125(3):337-41
15014411
Am J Orthod Dentofacial Orthop. 1997 Sep;112(3):244-51
9294351