Bonding orthodontics brackets to enamel using experimental composites with an iodonium salt.
OBJECTIVE
This study investigated whether the addition of diphenyliodonium chloride (DPC) to experimental resin bonding agents would allow fixation of brackets to enamel using shorter light exposure times.


METHODS
Photoactivated dimethacrylate-based composites were prepared containing DPC molar concentrations of 0 (control), 0.5 (R05), or 1 per cent (R1). Metallic brackets were bonded to bovine incisors and the bond strengths were evaluated using a shear test. In total, 18 groups were tested (n = 15 per group) defined by three bonding materials (control, R05, or R1), three light-activation time (8, 20, or 40 seconds), and two storage periods (10 minutes or 24 hours). The adhesive remnant index (ARI) was scored under magnification. Data were statistically analysed at a 5 per cent significance level.


RESULTS
At 10 minutes, the control composite showed lower bond strengths than the DPC-modified bonding agents for all light-activation times. Differences in bond strengths between both DPC-modified agents were not significant. Lower bond strengths at 10 minutes were generally observed for groups light activated for 8 seconds compared with groups light activated for 20 and 40 seconds. At 24 hours, no significant differences were observed among the light-activation times. The bond strengths at 24 hours were higher than the bond strengths at 10 minutes for all groups. A predominance of ARI scores 2 and 3 was generally observed.


CONCLUSIONS
The use of a ternary photoactivation system containing an iodonium salt in bonding composites may allow bonding brackets to enamel using reduced light exposure times.
*Department of Restorative Dentistry, Dental Materials Division Piracicaba Dental School, University of Campinas, Sao Paulo.
Ana R
AR
Costa
**Department of Orthodontics, Graduate Program in Orthodontics, University of Araras, Sao Paulo.
Mário
M
Vedovello-Filho
*Department of Restorative Dentistry, Dental Materials Division Piracicaba Dental School, University of Campinas, Sao Paulo.
Américo B
AB
Correr
**Department of Orthodontics, Graduate Program in Orthodontics, University of Araras, Sao Paulo.
Silvia A S
SA
Vedovello
***Department of Pediatric Dentistry, Piracicaba Dental School, University of Campinas, Sao Paulo.
Regina M
RM
Puppin-Rontani
****Materials Engineering School, and.
Fabricio A
FA
Ogliari
*****Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas, Rio Grande do Sul, Brazil.
Rafael R
RR
Moraes
*Department of Restorative Dentistry, Dental Materials Division Piracicaba Dental School, University of Campinas, Sao Paulo, sobrinho@fop.unicamp.br.
Lourenço
L
Correr-Sobrinho
D000269:Adhesives; D000818:Animals; D001713:Biphenyl Compounds / Q000737:chemistry*; D002417:Cattle; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel; D003799:Dental Stress Analysis / Q000379:methods; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D009861:Onium Compounds / Q000737:chemistry*; D016910:Orthodontic Brackets; D009970:Orthodontics; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength; D013499:Surface Properties
D000269:Adhesives; D001713:Biphenyl Compounds; D009861:Onium Compounds; D019279:Resin Cements; C031291:diphenyliodonium