Bonding of Self-Etch Adhesives in Curing-Activation Strategies to Root Canal

Objectives: To evaluate the bonding performance of various activation strategies to dual-cure one-step self-etch adhesives to root canal dentin.

Methods: 48 post spaces from human lower premolar were randomly applied with 4 dual-cure resin core systems as Estelite Core Quick(Tokuyama):ECQ, Clearfil DC Core Automix(Kuraray):CDC, Unifil Core EM(GC):UCE and BeautiCore(Shofu):BTC. All adhesives were applied with one of the following curing activation; Light curing for 10s (LA10s), Chemical curing (no light irradiation) with waiting intervals for 0(CA0s), 10(CA10s), and 30s(CA30s) prior to resin core material filling. Resin core materials were then filled and light-cured for 60s. After 24h storage, each specimen was serially sectioned into eight beam sticks for µTBS test. Regional µTBS data were statistically analyzed with 3-way ANOVA and Dunnette’s T3 test (p<0.05).

Results: ECQ and CDC in CA0s could not measure µTBS due to premature failure during specimen preparation.

Materials	Root regions	LA10s	CA0s	CA10s	CA30s
ECQ	Coronal	47.36±5.58Bg	n.d.	29.91±6.3Ac	30.63±2.81 Ade
	Apical	28.68±6.15Abc	n.d.	24.46±4.19Ac	24.86±2.47Abc
CDC	Coronal	37.14±5.07Be	n.d.	22.15±2.06Ac	23.05±1.65Ab
	Apical	26.29±6.52Bab	n.d.	13.41±0.94Aa	14.93±2.02Aa
UCE	Coronal	28.56±5.37Abc	27.42±4.11Acd	27.59±3.12Ac	28.42±5.58Acd
	Apical	22.55±5.3ABa	18.53±5.39Ab	19.76±2.74ABb	24.84±5.94Bbc
BTC	Coronal	41.94±7.58Bf	31.73±9.61Ad	34.5±5.75Ad	34.96±2.88Ae
	Apical	35.16±6.72Bde	26.17±7.05Ac	25.98±6.45Ac	29.53±5.34Acd

n=12 for each group. n.d.=no data available. The same superscript capital and small letters indicate no significant differences in µTBS for each row and column (p<0.05).

Conclusions: The waiting interval in chemical activation prior to filling resin core material could increase the bonding to root canal dentin.