Effect of prolonged photo-irradiation time of three self-etch systems on the bonding to root canal dentine.
OBJECTIVE
To evaluate the effect of photo-irradiation time to the adhesive on the regional bond strength of a dual-cure resin core material to root canal dentine using photo and dual-cure adhesives with self-etching primer.


METHODS
Post spaces were prepared in extracted premolars and then the root canal dentine was treated with one of the following bonding procedures: (1) Clearfil SE Bond Primer/Bond (SE), (2) Nano-Bond Primer/Photo-cure adhesive (PNB), (3) Nano-Bond Primer/Dual-cure adhesive (DNB). Photo-irradiation was performed for 10 or 20s from a coronal direction. The post spaces were then filled with a dual-cure composite resin (Build-It FR) and light-cured for 60s. After 24h storage, each specimen was serially sliced into 8, 0.6 x 0.6mm-thick beams for the microTBS test. The bond strength data were divided into coronal and apical regions and analysed using three-way ANOVA and Games-Howell multiple comparison (alpha=0.05).


RESULTS
The microTBS of the photo-cure adhesive resin, SE and PNB, significantly decreased (p<0.05) at the apical region when the photo-irradiation time was 10s. However, the bond strength of the SE group was significantly improved at both regions when photo-irradiation time was extended to 20s (p<0.05). There were no differences in microTBS of the photo-cure adhesive resin (PNB) cured for 20s and dual-cure adhesive resin (DNB) (p>0.05).


CONCLUSIONS
Photo-cure adhesive was effective for application on root canal dentine when the photo-irradiation time was sufficient. Extension of photo-irradiation time to the adhesive improved the bond strength depending on the type of adhesive resin.
Aksornmuang
Juthatip
J
Department of Prosthetic Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand. juthatip.a@psu.ac.th
Nakajima
Masatoshi
M
Foxton
Richard M
RM
Tagami
Junji
J
D000268:Adhesiveness; D000293:Adolescent; D001641:Bicuspid / Q000473:pathology; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects; D001840:Dental Bonding; D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry / Q000528:radiation effects*; D006801:Humans; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry / Q000528:radiation effects; D011176:Post and Core Technique / Q000295:instrumentation; D019279:Resin Cements / Q000737:chemistry / Q000528:radiation effects; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors
C483702:Build-it composite resin; C438313:Clearfil SE Bond; D003188:Composite Resins; C095997:DCR cement; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C514426:Nano-Bond primer dual-cure adhesive; D019279:Resin Cements