Sodium hyaluronate accelerates the healing process in tooth sockets of rats

Objective: In this study we evaluated the effects of sodium hyaluronate (HY) in the healing process of tooth sockets of rats. Design: Immediately after the extraction of the upper first molars of male Holtzman rats, right sockets were treated with 1% HY gel (similar to 0.1 ml), while left sockets were used as control (blood clot). The animals were sacrificed at 2,7, and 21 days after tooth extraction and upper maxillaries processed for histological and morphometric analysis of the apical and medium thirds of the sockets. Carbopol, an inert gel, was used to evaluate the mechanical effect of gel injection into sockets. Expression of bone morphogenetic protein-2 (BMP-2) and osteopontin (OPN) was determined by immunohistochemistry at 1, 2, 3, 4, 5, and 7 days after tooth extraction. Results: Histological analysis showed that HY treatment induced earlier trabecular bone deposition resulting in a bone matrix more organized at 7 and 21 days after tooth extraction. Also, HY elicited significant increase in the amount of bone trabeculaes at 7 and 21 days after tooth extraction (percentage of trabecular bone area at 7 days: 13.21 +/- 4.66% vs. 2.58 +/- 1.36% in the apical third of control sockets) and in the vessels counting at 7 days. Conversely, the number of cell nuclei was decreased in HY-treated sockets. Additionally, expression of BMP-2 and OPN was enhanced in HY-treated sockets compared with control sockets. Conclusions: These findings suggest that HY accelerates the healing process in tooth sockets of rats stimulating the expression of osteogenic proteins. (C) 2008 Elsevier Ltd. All rights reserved.