Effect of curing time on the bond strength of a bracket-bonding system cured with a light-emitting diode or plasma arc light.
The purpose of this study was to assess the influence of two light units, a light-emitting diode (LED) and a plasma arc light (PAC), on the shear bond strength (SBS) of brackets bonded to enamel. Ninety bovine teeth were divided into six groups, according to the light-curing unit and exposure times used. In the LED (Ortholux; 3M-Unitek) group, the specimens were light cured for 5, 10, and 15 seconds. In the PAC (Apollo 95E; DenMed Technologies) group, the specimens were light cured for 3, 6, and 9 seconds. The brackets were bonded with Transbond XT (3M-Unitek), stored in distilled water at 37 °C for 24 hours and then submitted to SBS testing in a universal testing machine. The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the teeth. According to analysis of variance and Tukey multiple comparisons test, the highest mean SBS was obtained with the LED at 15 seconds (16.68 MPa), which did not significantly differ from the LED 10 (14.76 MPa) or 5 (13.92 MPa) second groups (P > 0.05). The LED 10 and 5 second groups were not significantly different from the PAC 9 second group (12.66 MPa) or from the PAC 6 second group (9.96 MPa). The lowest mean SBS was obtained with the PAC 3 second group (8.29 MPa), which did not differ significantly from the PAC 6 second group. The method of light curing did not influence the ARI, with score 3 predominant. The LED at 5 seconds and the PAC at 3 seconds provided sufficient mean SBS to resist either orthodontic or masticatory forces.
Dall'Igna
Carine Maccarini
CM
Department of Orthodontics, School of Dentistry, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil.
Marchioro
Ernani Menezes
EM
Spohr
Ana Maria
AM
Mota
Eduardo Gonçalves
EG
D000268:Adhesiveness; D000818:Animals; D002417:Cattle; D055117:Curing Lights, Dental / Q000145:classification*; D003743:Dental Enamel / Q000648:ultrastructure; D003799:Dental Stress Analysis / Q000295:instrumentation; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation*; D008422:Materials Testing; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000737:chemistry / Q000528:radiation effects*; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
D019279:Resin Cements; C477790:Transbond XT; D014867:Water