Hyaluronidase‐enhanced connective‐tissue attachment to demineralized root and pulpal dentin

Abstract Treatment of demineralized dentin with hyaluronidase seems to increase exposure of collagen fibrils. The present study compared the in vivo connective‐tissue response to dentin treated with citric acid alone and with citric acid plus hyaluronidase. Dentin specimens were obtained from areas beneath attached periodontal ligament fibers on extracted human teeth. Each rectangular specimen had a face of root surface dentin and an opposite surface composed of pulpal dentin. One group was treated with citric acid alone (A); a second group with both citric acid and hyaluronidase (AH); and a third group served as untreated controls (C). Specimens were examined in the scanning electron microscope (SEM) for morphologic characteristics, and used in an implantation model to evaluate cell, connective‐tissue and epithelial responses. In the latter procedures, specimens were implanted transcutaneously into incisional wounds on the dorsal surfaces of rats. Four specimens in each group were evaluated 10 days after implantation and analyzed using histologic and histometric methods. SEM examination showed that the surface of the control specimens had a smear layer which concealed the openings of dentinal tubules. Dentinal tubule orifices were present on the surface of A and AH specimens. Enhanced exposure of the collagen fibrils was apparent on AH surfaces. The histologic and histometric analyses of A and AH groups showed that cell adhesion and fiber density did not differ between root and pulpal surfaces, or between A and AH‐treated implants. However, a significantly greater number of cells were attached to A and AH surfaces than controls. In addition, fiber attachment was not present in the control group. A distinct eosinophilic surface zone was present on A and AH surfaces, which was significantly wider on pulpal surfaces and in AH specimens. The connective‐tissue attachment that occurred in A and AH groups inhibited epithelial down‐growth. The length of implant surface exhibiting connective‐tissue attachment was significantly greater in AH specimens. It appeared that hyaluronidase treatment of the exposed collagen had increased the area of connective‐tissue attachment to the implant surface.