Microtensile bond strength of a nanofilled composite resin to human dentin after nonvital tooth bleaching.
OBJECTIVE
The purpose of this in vitro study was to measure the microtensile bond strength of a nanofilled composite resin to human dentin after nonvital bleaching at different post-bleaching time intervals, and to analyze the fracture mode under SEM.


METHODS
Thirty-six sound human maxillary premolars extracted for orthodontic reasons were prepared in a standardized manner, and randomly assigned to four groups (n = 9): non bleached (control) (NB); bleached with sodium perborate and 35% hydrogen peroxide (SP-HP); bleached with 35% hydrogen peroxide (HP); and bleached with 37% carbamide peroxide (CP). Each group was subdivided into 3 subgroups (n = 3): restored immediately (RO); restored after 7 days (R7); and restored after 14 days (R14). The teeth were stored in distilled water for 24 h, sectioned 4 mm below cementoenamel junction, and the crown was serially sectioned to obtain sticks (0.9 mm2 cross section) for microtensile bond strength testing. The microTBS samples were attached to a universal testing machine (Instron, model 4444), using a Geraldeli's device. The test was performed until the fracture of the specimens, and all specimens were analyzed under a scanning electron microscope (Philips XL-30).


RESULTS
Two-way ANOVA (p = 0.05) revealed that there were no statistically significant differences of bond strength values for the bleaching agents used, or at different post-bleaching time intervals.


CONCLUSIONS
It was concluded that the definitive restoration can be accomplished immediately after nonvital bleaching treatment.
Arcari
Gilberto Müller
GM
Department of Operative Dentistry, Federal University of Santa Catarina, Florianopolis, SC, Brazil. garcari@terra.com.br
Araújo
Elito
E
Baratieri
Luiz Narciso
LN
Lopes
Guilherme Carpena
GC
D000704:Analysis of Variance; D001641:Bicuspid; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D001840:Dental Bonding; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites; D019279:Resin Cements; D013718:Tensile Strength; D014073:Tooth Bleaching; D019553:Tooth, Nonvital
D003188:Composite Resins; D017220:Dentin-Bonding Agents; C474035:Filtek Supreme; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate