CPNE7 Induces Biological Dentin Sealing in a Dentin Hypersensitivity Model

Dentin hypersensitivity commonly occurs due to opened dentinal tubules for many reasons. In our previous study, copine 7 (CPNE7) could induce dentin formation for an indirect pulp-capping model in vivo. This study aims to investigate the formation of tertiary dentin when CPNE7 is applied to intentionally exposed dentin with nothing over it in vivo, whether it affects microleakage of the teeth, and the penetration ability of CPNE7 molecules through dentinal tubules in vitro. Cervical dentin areas of 6 maxillary incisors of 5 beagles were exposed to a class V-like lesion, and 1 side of 3 maxillary incisors was adapted with recombinant CPNE7 protein for 5 min as the experimental group. The other side was the control group, and there was no treatment of ethylenediaminetetraacetic acid (EDTA) and CPNE7 after preparation. The defects were exposed without any restorations, and all beagles were sacrificed after 4 wk. The fluid penetration of exposed dentin areas was investigated by a microleakage-testing device and confocal laser scanning microscope. Tertiary dentin formation was confirmed with histological scanning electronic microscopic analysis. Tertiary dentin formation reduces dentinal fluid flow due to occluded tubules or discontinuity with primary or secondary dentin. The in vivo hypersensitivity model with the anterior teeth of beagle dogs showed newly formed tertiary dentin at the dentin-pulp boundary in recombinant CPNE7-treated teeth when compared with the untreated control group in histologic analysis. Scanning electronic microscopic analysis revealed occluded sites with mineral deposition of intratubular dentin. In the permeability test, the mean microleakage value of the CPNE7-treated group was significantly lower than that of the control group (P < 0.05). The tubular penetration of rhodamine B-combined CPNE7 was confirmed under confocal laser scanning microscope. CPNE7 induces formation of tertiary dentin through shallowly exposed dentinal tubules, which decreases dentin permeability.