The purpose of this study was to examine the effect of immediate dentin sealing on the adhesion of CAD/CAM
ceramic onlay restoration with/without dynamic cyclic load stress. Standardized MODP cavities were prepared
in 40 extracted human upper molars. The intra-cavity dentin walls of 20 cavities (C+) were sealed, and the walls
of the other 20 cavities (C-) were not sealed. CAD/CAM ceramic onlays were made by CEREC. Each ceramic
onlay was bonded to an individual cavity with a resin luting cement. One half of the restored specimens were
subjected to a dynamic cyclic load stress condition (S+, 157 N × 300,000 times in 37°C water), and the other half
of the specimens were unstressed (S-). Four beam specimens were trimmed from each restored specimen, and
micro-tensile bond strength (μ-TBS) to pulpal dentin wall was measured. The data of μ-TBS were examined
using two-way ANOVA, Tukey’s q-test and Weibull analysis. Mean values (SD) of μ-TBS in MPa and <Weibull
modulus> were C+S-: 10.73 (2.03) <6.03>; C+S+: 8.11 (1.82) <4.84>; C-S-: 10.79 (1.78) <6.79>; C-S+: 6.47(1.88) <3.59>.
The dynamic cyclic load stress reduced the μ-TBS significantly and the immediate dentin sealing increased the
μ-TBS significantly as compared with the unsealed specimens. The values of C+S+ specimens were significantly
greater than those of C-S+ specimens. Immediate dentin sealing increased the bonding durability under the
dynamic cyclic load stress condition. The μ-TBS of CAD/CAM ceramic onlay restoration to pulpal dentin wall
was influenced by the dynamic cyclic load stress. It seemed that the immediate dentin sealing improved the
adhesion of the CAD/CAM ceramic onlay restoration.
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