<>Objective: To investigate
ground enamel bond strength loss of currently popular adhesives after bleaching
procedure, in vitro. Method: Each adhesive was tested by two protocols. They
are with (B. R) and without (B.) reducing agent treatment after bleaching.
Ground enamel was imbedded in acrylic mold, and was finished with 320 grit SiC
sand paper. Opalescence Xtra
®
(Ultradent) with 35% of H
2O
2 was applied to enamel surface prepared.
Agitation was applied after 5minutes and followed by 20s light curing at
500mW/cm
2 for 10min. Bleach
gel was rinsed off with a strong stream of water for 30s. In B.R group, strong
reducing agent 50%Na
2S
2O
3 was applied for 20s with agitation by a brush, and
then was rinsed off by water. Shear bond strength (SBS)
of
One-Step (OS) (Bisco), Single Bond (SB) (3M), Solo Plus (SP) (Kerr), Prime Bond
NT (PB) (Dentsply) and new Bisco experimental version, Bleach N' Bond (BB) was
measured after etching of immediately bleached enamel for 15s with 32% H
3PO
4(Uni-Etch
â/Bisco), and soaking bonded specimens
in DI water for 2hr. at 37°C. Control
data was tested without bleaching and reducing procedure. Data analyzed by
ANOVA followed by Student-Newman-Keuls test.
<>Results:
(Bonding area=0.1521cm
2, Shear speed = 5mm/min)
|
Group
(n=5)
|
BB
(sd)
|
<>SB
|
SP
|
OS
|
PB
|
|
  Control MPa (sd)
|
24.83(2.35)
|
20.7(3.62)
|
22.56(1.85)
|
27.69(2.79)
|
22.42(4.19)
|
|
B group MPa (sd)
|
23.70(4.01)
|
14.17(3.93)
|
19.38(2.06)
|
15.58(2.24)
|
17.49(1.56)
|
|
SBS retention
|
95.4%
|
68.5%
|
85.9%
|
56.3%
|
78.0%
|
|
B.R group MPa (sd)
|
22.48(2.62)
|
15.86(1.88)
|
16.39(2.05)
|
14.64(2.79)
|
16.81(1.26)
|