Effect of high-intensity LED units at reduced curing time on in vitro bond strength of orthodontic brackets.
OBJECTIVE
To compare the shear bond strength of stainless steel brackets obtained by 3 high-intensive light-emitting diode (LED) units with conventional halogen polymerization.


METHODS
A standard light-curing adhesive paste was used to bond brackets using different lamps and curing times. Eighty permanent bovine incisors were obtained and randomly divided into 4 groups. The first group was bonded using a high-output halogen lamp for 20 seconds, which served as a positive control. The other 3 groups were bonded with high-intensive LED curing devices for 10 seconds. After 30 minutes, a universal testing machine was used to apply an occlusal shear force directly to the enamel-bracket interface at a speed of 0.5 mm/minute. The groups were compared using Kruskal-Wallis test.


RESULTS
Mean results and standard deviations for the groups were: group 1 = 11.22 MPa (1.68), group 2 = 10.35 MPa (1.92), group 3 = 11.19 MPa (2.62), and group 4 = 11.82 MPa (2.09). No significant difference was observed in the bond strengths of the 4 groups evaluated (P = . 176).


CONCLUSIONS
Under the conditions of the present study, the high-intensity LED units with reduced light-curing time bonded brackets to etched tooth enamel as well as the halogen-based light-curing units.
Palomares
Nathália B
NB
School of Dentistry, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
Cal-Neto
Julio Pedra e
JP
Sampaio-Filho
Hélio
H
Almeida
Marco Antônio de Oliveira
MA
Miguel
José Augusto Mendes
JA
D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000528:radiation effects; D002417:Cattle; D016009:Chi-Square Distribution; D003188:Composite Resins / Q000528:radiation effects; D001840:Dental Bonding / Q000295:instrumentation / Q000379:methods*; D003762:Dental Instruments; D003799:Dental Stress Analysis; D008027:Light; D008029:Lighting / Q000295:instrumentation; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000528:radiation effects*; D033081:Shear Strength; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013997:Time Factors
D003188:Composite Resins; D019279:Resin Cements; C477790:Transbond XT; D017438:Bisphenol A-Glycidyl Methacrylate