Histopathological changes in periodontal tissue during experimental apical periodontitis and its correction with hydroxyapathite and lysozyme

Apical periodontitis is an inflammatory disease of periapical tissues. Despite advances in treatment, persistent cases highlight the need for innovative therapeutic approaches, including osteoinductive and antibacterial substances. The objective of this study was to evaluate the histopathological effects of hydroxyapatite (HAP) and lysozyme on experimentally induced apical periodontitis (AP) in rats. Apical periodontitis was induced in Wistar rats by injecting bee venom into the pulpal cavity of maxillary molars. The rats were divided into seven groups (6 animals each), including a control group, AP groups, as well as groups with isolated application of HAP and groups with combined application of HAP and lysozyme. Histopathological changes in the periodontal tissues and surrounding bone were analyzed using descriptive histopathological method. AP caused significant degenerative and inflammatory changes, including edema, vascular congestion, and osteoclastic bone resorption. HAP alone reduced osteoclastic activity at 30 days but showed minimal anti-inflammatory effects. The combination of HAP and lysozyme significantly reduced inflammation, normalized bone remodeling, and enhanced reparative regeneration at both time points. The combined use of HAP and lysozyme demonstrates synergistic effects in mitigating AP-induced inflammation and promoting periodontal regeneration, providing a promising approach for AP treatment.