The efficacy of hyaluronic acid treatment on induced periodontitis in rats exposed to gamma radiation

Abstract

The periodontium is one of the radiation-sensitive tissues; the periodontal membrane's vascularity and cellularity were reduced, and the danger of losing periodontal attachment was raised. This study was performed to evaluate the efficacy of hyaluronic acid treatment on induced periodontitis in rats exposed to gamma radiation radiographically and histopathologically. A total number of 30 adult male Albino rats were divided randomly into five groups (n = 6). Group 1 (C): received neither irradiation nor treatment. Group 2 (P): was subjected to induced periodontitis. Group 3 (PT): subjected to induced periodontitis with hyaluronic acid treatment. Group 4 (RP): received a single dose of total cranium irradiation 20 Gy with induced periodontitis. Group 5 (RPT): received a single dose of total cranium irradiation 20 Gy with induced periodontitis and hyaluronic acid treatment. All animals were euthanized, and the outcomes of treatment were evaluated radiographically by cone beam computed tomography (CBCT) and histopathologically. Results: Comparison of the five groups about bone density by one-way ANOVA showed a significant difference among groups (P < 0.001). The highest bone density values were measured in Group (PT) (1245 ± 22.86), while the lowest bone density values were measured in Group (RP) (926 ± 31.47). Using post hoc analysis for pairwise comparisons showed that Group (PT) and Group (RPT) have significantly higher values than Group (P) and Group (RP) (P < 0.001). Histologically, the group (RPT) shows a new formation of irregular connective tissue fibers of the periodontal ligament (PDL) with an area of distortion, fibrous marrow spaces with wide osteocyte lacunae without nuclei, and Haversian canals with empty blood vessels. The radiographic and histopathological findings of using HA as a topical application in rats subjected to induced periodontitis and exposed to gamma radiation revealed enhanced healing ability of the periodontal tissue with restoration of the bone density. Depending on these results, HA could be used as an adjunct local delivery agent for periodontal-affected patients receiving radiotherapy.

Keywords: Bone density; CBCT; Gamma radiation; Hyaluronic acid; Periodontitis.

Fig. 1

Clinical and radiographic photo of established periodontitis.

Fig. 2

A photomicrograph (A) and (B) showing group (C); PDL (double head arrow). Sharpey’s fibers (dot line). Osteocytes (black arrow), Haversian canals (Hc), Volkmann’s canal (Vc), blood vessels (Bv). (C) and (D) showing group (P); loss of bone and attachment (stars). Osteoclast (black arrow). Osteocytes (red arrows), Howship’s lacunae (Hl), resting line (Re) (blue arrows). (E) and (F) showing group (PT); PDL (black arrows), new collagen formation with irregular orientation (circle). neurovascular canal (star). Empty lacunae (arrowhead), osteocytes (yellow arrows), reversal line (blue arrows). B bone, D dentin (H&E Orig. Mag. × 100).

Fig. 3

A photomicrograph (A) and (B) showed group (RP); destructed PDL (black stars). Many osteoclastic cells (black arrow). Wide osteocyte lacunae with eccentric osteocyte (blue arrow). Bone trabeculae (Bt), entrapped osteocytes (yellow arrow), absence of osteocytes (yellow stars). Fibrous bone marrow (F). (C) and (D) revealed group (RPT) with irregular connective tissue fibers of PDL (dot lines) with area of distortion (blue circle). (C) Necrotic bone (double head arrows), areas of periodontal tissue degradation (black star). Wide osteocyte lacunae with empty nuclei (yellow arrows). Empty Haversian canals from blood vessels (black dot circle) (D), B bone, D dentin. (H&E Orig. Mag. × 100).

Fig. 4

A Photomicrographs (A) and (B); showed group (C); homogenous compact bone (double-headed arrow), osteocytes (arrow). (C) revealed group (P); osteocytes (arrow), destruction in bone, and PDL (dot circles). (D) Represented group (PT); osteocytes (arrow), restoring of PDL (dot circles) (Alcian blue Orig. Mag. × 100).

Fig. 5

Photomicrographs (A) and (B) showed group (RP); In photomicrograph (A), compact bone (double-headed arrow), area of bone destruction (black arrow), and absence of osteocytes (dot circles). Photomicrograph (B) showed a thin small bone trabecula of spongy bone (double-headed arrow) and fatty bone marrow (stars). In groups (RPT) (C) and (D); newly formed bony spicules (double-headed arrow), with many collagens’ fibers formation (dot circles) (Alcian blue Orig. Mag. × 100).