Histological evaluation of nonsurgical periodontal treatment with and without the use of sodium hypochlorite / amino acids and cross-linked hyaluronic acid gels in dogs

Abstract

Objectives: To evaluate periodontal wound healing following scaling and root planing (SRP) in conjunction with the application of sodium hypochlorite/amino acids and cross-linked hyaluronic acid (xHyA) gels in dogs.

Materials and methods: In four beagle dogs, 2-wall intrabony defects were created and metal strips were placed around the teeth. Clinical parameters were measured 4 weeks after plaque accumulation. The experimental root surfaces were subjected to SRP with either the subgingival application of a sodium hypochlorite/amino acid gel and a xHyA gel (test group) or SRP alone (control group) using a split-mouth design. Clinical parameters were re-evaluated at 6 weeks. The animals were sacrificed at 8 weeks for histological analysis.

Results: The test group showed significant improvements in all clinical parameters compared to the control group. Histologically, the test group exhibited statistically significantly greater new bone formation [i.e., length of newly formed bone, new bone area] compared with the control group (p < 0.05). Furthermore, statistically significantly greater formation of new attachment [i.e., linear length of new cementum adjacently to newly formed bone with inserting collagen fibers] and new cementum was detected in the test group compared with the control group at 8 weeks (p < 0.05 and p < 0.01, respectively).

Conclusion: The adjunctive subgingival application of sodium hypochlorite/amino acid and xHyA gels to SRP offers an innovative novel approach to enhance periodontal wound healing/regeneration.

Clinical relevance: The present findings have for the first-time shown histologic evidence for periodontal regeneration in support of this novel treatment modality.

Keywords: Cross-linked hyaluronic acid; Non-surgical periodontal therapy; Periodontal wound healing/regeneration; Periodontitis; Sodium hypochlorite/amino acids.

Fig. 1

a Surgically created two-wall intrabony defects in mandible. b Placement of the metal strips on the denuded root surfaces. c Plaque accumulation after 4 weeks. d Standardized measurement of clinical parameters by using customized acrylic stents with guiding grooves at baseline

Fig. 2

a Application of sodium hypochlorite/amino acid gel to the periodontal pocket. SRP performed using an ultrasonic device with an ultrasonic tip (b) and hand instruments (c). d Application of a xHyA gel to the periodontal pocket

Fig. 3

Clinical overview at baseline, 4 days, 2, 4 and 8 weeks in the control (a-e) and the test group (f-j)

Fig. 4

a Histologic overview of defect treated with SRP alone (control group). (scale bar, 1 mm; hematoxylin and eosin stain). b Higher magnification of the box 1 area. c Higher magnification of the box 2 area. d Higher magnification of the box 3 area. e Higher magnification of the box 4 area. f Higher magnification of the box 5 area. g Higher magnification of the box 6 area. (scale bar, 200 µm; hematoxylin and eosin stain). D, root dentin; N_1, apical end of root planing; N_2, cementoenamel junction; OGE, oral gingival epithelium; OSE, oral sulcular epithelium; JE, apical end of junctional epithelium; CT, gingival connective tissue; NB, new bone; NC, new cementum

Fig. 5

a Histologic overview of defect treated with SRP with a sodium hypochlorite and amino acids gel and a cross-linked hyaluronic acid gel (xHyA) gel (test group). (scale bar, 1 mm; hematoxylin and eosin stain). b Higher magnification of the box 1 area. c Higher magnification of the box 2 area. d Higher magnification of the box 3 area. e Higher magnification of the box 4 area. f Higher magnification of the box 5 area. g Higher magnification of the box 6 area. (scale bar, 200 µm; hematoxylin and eosin stain). D, root dentin; N_1, apical end of root planing; N_2, cementoenamel junction; JE, apical end of junctional epithelium; CT, gingival connective tissue; NB, new bone; NC, new cementum; NPL, new periodontal ligament

Fig. 6

a Higher magnification view of the middle portion of the defect treated with SRP alone (control group). Loosely arranged collagen fibers were seen near the root dentin without new cementum. (scale bar, 200 µm; azan stain). b Higher magnification view of the middle portion of the defect treated with SRP with a sodium hypochlorite and amino acids gel and a cross-linked hyaluronic acid gel (xHyA) gel (test group). Dense obliquely oriented collagen fibers were observed between the new bone and cementum. (scale bar, 200 µm; azan stain). D, root dentin; NB, new bone; NC, new cementum; NPL, new periodontal ligament