Effects of zinc deficiency on oral and periodontal diseases in rats

Abstract

The aim of this study was to investigate the alterations of oral and periodontal tissues in zinc-deficient rats compared with control rats. The study was carried out on 14 Sprague-Dawley rats, cessation of lactation on the 24th day after birth. Rats were randomly divided into two groups. Group I rats were fed with a zinc-deficient diet and group II rats were fed with a zinc-containing diet. At the end of the fourth week on experimental diets, alterations of the oral tissues in both groups were recorded. In addition, the gingival index (GI-Löe-Silness), plaque index (PI-Silness-Löe) and periodontal pocket depth scores were recorded in order to assess periodontal tissue health in the rats. Then, blood samples were taken and the serum zinc levels measured by atomic absorption spectrophotometry. At the end of the experiment, oral tissue samples were investigated by light microscopy. Finally, the results of the two groups were compared by using the Student's t-test. The effects of zinc deficiency were observed at 10-16 d in rats. Although body weight, body length and tail length were retarded in zinc-deficient rats, they were advanced in rats fed with a zinc-containing diet. The mean plaque index and gingival index for group II rats were significantly lower than for group I rats (p<0.001), but there was no significant difference regarding pocket depth between the two groups of rats (p>0.05). Aphthous ulcer was often seen in the study group, where it was observed on the alveolar mucosa with a high rate of 29.9%. According to histological findings, there was no difference related to the epithelial keratinization of the hard palate between the two groups. However, hyperkeratosis was found on the dorsal surface of the tongue in zinc-deficient rats. The findings indicated that oral health was better in group II rats (those fed with a zinc-containing diet) than in group I (zinc-deficient) rats. Hyperkeratinization was more prominent in zinc-deficient rats. We suggest that zinc deficiency is a potential risk factor for oral and periodontal diseases.