Protective effect of ellagic acid on healing alveolar bone after tooth extraction in rat--a histological and immunohistochemical study

Abstract

Objective: This study has attempted to evaluate the effects of ellagic acid (EA) on alveolar bone healing after tooth extraction in rats.

Design: Twenty-four Sprague Dawley (SD) male rats (200-250g) were selected and were anaesthetised for the extraction of upper left incisor. Then, the rats were divided into two groups, comprising 12 rats each; the first group has been considered as a control group and was given only normal saline, whereas, the second group (treated group) was intragastrically administrated with EA daily once, for 28 days. Then three rats from each group had been selected on 7th, 14th, 21st, and 28th days to dissect their maxilla tissue either for histological observation and homogenisation purposes. The tissues fixed, decalcified and embedded in paraffin. Serial sections of 5μm thickness were prepared and stained with haematoxylin and eosin (H&E) for the histological study. Similar sections were taken for immunohistochemical analysis to assess osteocalcin (OSC) and osteopontin (OPN). Furthermore, Malondialdehyde (MDA) and superoxide dismutase (SOD) were measured in homogenated gingival maxilla tissue of rat by commercial kit.

Results: Based on the histological analysis we have identified that, EA treatment has induced earlier trabecular bone deposition in the treated group, resulting in more organised bone matrix on the 14th, 21st, and 28th days after tooth extraction, as against the control group. In comparison to control group, the positive labelling of OSC and OPN of the treated group have been highly expressed in the alveolar socket on 14th, and 21st days, which has indicated a the possibility of formation of new bone trabeculae at the beginning of the mineralisation process, after tooth extraction. In the EA treatment group, lipid per-oxidation (MDA) was significantly decreased (P<0.05), as opposed to the control group. However, the antioxidant defense enzyme (SOD) was significantly increased in the maxilla tissue treated with EA (P<0.05), compared to control group, which suggests that, after tooth extraction, EA plays an important role in the protection against the induction of lipid per-oxidation, particularly after 28 days of treatment with EA.

Conclusion: This study has concluded that, EA may accelerated the healing process in teeth socket of rats. Furthermore, the EA treated group showed a stronger positive immunolabelling for OSC and OPN, when compared with the control group.

Keywords: Alveolar bone; Antioxidant; Ellagic acid; Osteocalcin; Osteopontin; Teeth socket.