Low-intensity pulsed ultrasound promotes periodontal regeneration in a beagle model of furcation involvement

Abstract

Objective: To evaluate the regeneration potential of periodontitis tissue treated by low-intensity pulsed ultrasound (LIPUS) combined with the guided tissue regeneration (GTR) technique in a beagle model of furcation involvement (FI). Background: Achieving predictable regeneration remains a clinical challenge for periodontitis tissue due to the compromised regenerative potential caused by chronic inflammation stimulation. LIPUS, an FDA-approved therapy for long bone fracture and non-unions, has been demonstrated effective in the in vitro attenuation of inflammation-induced dysfunction of periodontal ligament stem cells (PDLSCs), the key cells contributing to periodontal regeneration. However, the in vivo effect of LIPUS on periodontitis tissue is rarely reported. Methods: A beagle model of FI was established, and the experimental teeth were randomly assigned into three groups: control group, GTR group, and GTR+LIPUS group. Radiographic examinations were performed, and clinical periodontal parameters were recorded to reflect the periodontal condition of different groups. Histological analyses using H&E and Masson's staining were conducted to evaluate the periodontal tissue regeneration. Results: LIPUS could enhance new periodontal bone formation and bone matrix maturity in FI after GTR treatment. Moreover, clinical assessment and histomorphometric analyses revealed less inflammatory infiltration and superior vascularization within bone grafts in the LIPUS treatment group, indicating the anti-inflammatory and pro-angiogenic effects of LIPUS in FI. Conclusion: Our investigation on a large animal model demonstrated that LIPUS is a promising adjunctive approach for the regeneration of periodontitis tissue, paving a new avenue for LIPUS application in the field of periodontal regenerative medicine.

Keywords: beagle dog; furcation involvement; inflammation; low-intensity pulsed ultrasound; regeneration.

FIGURE 1

Beagle FI model establishment. (A) Modeling procedures: a. flap elevation, b. establishment of the “U”-shaped defect and stainless-steel ligature fastening, c. LIPUS treatment, and d. ultrasonic therapeutic device. (B) Postoperative radiographic observation. (C) Clinical assessment of BI, PD, and AL before and after the modeling procedure. Data are presented as mean ± SD. *p < 0.05. (D) SEM image of the PTFE membrane.

FIGURE 2

Clinical periodontal parameters of different groups. BI (A), PD (B), and AL (C) of the control group, GTR group, and GTR+LIPUS group. Data are presented as mean ± SD.

FIGURE 3

Histological and histomorphometric analyses. (A) Schematic illustration of histomorphometric measurements. N: notch; V: vertex of furcation; NC: new cementum; NC% = NC/NV×100%; NP: new periodontal ligament; NP% = NP/NV×100%; NBA: new bone area; DA: defect area; NBA% = NBA/DA×100%. (B) Representative H&E staining of the furcation area. The dotted lines indicate a new bone formation area. Scale bar, 400 μm. (C) Quantitative analysis of new cementum formation, periodontal ligament formation, and bone formation areas. Data are presented as mean ± SD, *p < 0.05.

FIGURE 4

Histological assessment of inflammatory infiltration and neovascularization. (A) Lymphocyte infiltration of the control group, GTR group, and GTR+LIPUS group. Scale bar, 200 μm. (B) Inflammatory infiltration scores of different groups; *p < 0.05. (C) Blood vessels in the defect area are indicated by white arrows. Scale bar, 200 μm. (D) Neovascularization scores of different groups; *p < 0.05.

FIGURE 5

Histological assessment of periodontal attachment. Masson’s trichrome staining of the control group, GTR group, and GTR+LIPUS group. Scale bar, 200 μm.