INTRODUCTION

Free radicals can be defined as molecules or molecular fragments with an unpaired electron which imparts certain characteristics to the free radicals such as reactivity [1]. Reactive free radicals are able to produce chemical modifications and to damage proteins, lipids, carbohydrates, and nucleotides in the tissues [2]. It is known that free radicals are probably mediators for tissue damage in neoplastic diseases [3]. Reactive free radicals may damage cells by initiation of lipid peroxidation that causes profound alteration in the structural integrity and unctions of cell membrane [2]. Free radical induced lipid peroxidation has been implicated in the pathogenesis of several disorders including cancer. The concentration of lipid peroxidation product Malonaldehyde (MDA) is most widely used [4, 5]. Saliva is a diagnostic sample for many oral and systemic diseases [6]. In this study, role of free radicals (salivary MDA) in dental conditions such as oral submucous fibrosis, candidiasis, dental caries, leukoplakia and oral cancer has been explored. Effect of vitamin C supplementation on salivary MDA levels was also explored.

MATERIALS AND METHODS

Subjects: 25 patients (M:F , 13;12) of leukoplakia, 47 (M:F, 16:21) of oral submucous fibrosis, 62 (M;F, 8:4) of oral cancer, 67 (M:F 31:36) of dental caries and 21 patients (M:F, 11:10) of candidiasis in age group 15-60 yrs attending Out Patient Department of Maharashi Markendeswar University, MullanaAll diagnostic tests were done for diagnosing particular diseases. 50 (M:F, 25:25) healthy subjects in age group 15-60 yrs were taken as controls. Non-stimulated whole saliva samples were collected and transported over ice. Samples were centrifuged and stored at -200C. MDA was analysed by Thiobarbituric Acid (TBA) reaction [7].

RESULTS

Elevated salivary MDA levels were observed in patients with dental caries and candidiasis as compared with controls although the difference was not statistically significant (3.42 ± 0.22 (M) & 3.36 ± 1.42 (F), 3.45 ± 1.39 (M) & 3.29 ± 1.37 (F) v/s 3.38 ± 0.33 (M) & 3.24 ± 0.54(F) ng .ml-1, respectively p>0.05). While significantly high MDA levels were observed in leukoplakia, oral submucous fibrosis and cancer (Table 1, p<0.05). After vitamin C supplementation decrease in MDA levels was observed only in patients of dental caries and candidiasis. This decerease was not statistically significant. Not much change was observed in MDA levels in leukoplakia, oral submucous fibrosis and cancer.

DISCUSSION

Lipid peoxidation has been shown to cause a profound alteration in structural integrity and functions of cell membrane. A study in a baby hamster kidney cell line and its polyoma-virus transformed malignant counterpart reported high levels of lipid peroxidation products and low levels of alpha tocopherol in transformed cells suggesting that lipid peroxidation is increased in the precancerous conditions and malignant state [8]. In the present study high MDA levels were observed in leukoplakia, oral submucous fibrosis and cancer as compared to controls (table 1, P< 0.05), indicating a role of free radicals in pathogenesis of precancerous lesions and cancer.

Table 1: Salivary MDA levels of patients with dental caries, candidiasis, leukoplakia, oral submucous fibrosis, oral cancer and controls (Mean +/- SD)

*Significant at the level of p <0.05.

Elevated MDA levels have been reported.in oral leukoplakia and cancer [9, 10]. The body contains a number of protective antioxidant mechanisms, whose specific role is to remove harmful oxidants as they form, or to repair damage caused by reactive oxygen species [11]. Recent medical and dental research is geared towards prevention of free radical medicated diseases by using specific antioxidants. Preliminary data indicates protective role of anti-oxidant supplementation in prevention of precancerous lesions [12]. In our study it has been observed that anti-oxidant vitamin C supplementation for six weeks was helpful in patients of dental caries and candidiasis but for leukoplakia, oral submucous fibrosis and oral cancer prolonged supplementation is recommended. Saliva being a non invasive and easy to collect sample, can be used to assess MDA and anti-oxidant status of patient with an oral lesion.

Further studies on larger scale should be performed to clarify the importance and role of anti-oxidant vitamins in oral diseases.

Conflicts of Interests: All authors have none to declare.

REFERENCES

1. Slater FT: Free radical mechanisms in tissue injury. Biochem. J. 1984:333:1-15.
2. De Zwart LL, Meerman JHN, Commandeur JNM et al: Biomarkers of free radical damage applications in experimental animals and humans. Free Radic. Biol. and Med. 1999:26:202-26.
3. Haliwell B, Gutteridge JMC. Free radicals in biology and medicine, Oxford University Press Inc. New York. 2002:701-707.
4. Draper HH, Haley M. Malondialdehyde determination as index of lipid peroxidation. Methods Enzymol. 1990:186:421-31.
5. Öztürk LK, Furuncuoglu H, Atala MH, Uluköylü O, Akyüz S and Yarat A. Association between dentaloral health in young adults and salivaryglutathione, lipidperoxidation and sialic acid levels and carbonic anhydrase activity. Braz. J. Med. Biol. Res.2008:41:956-959.
6. Mandel ID. The role of saliva in maintaining oral homeostasis. JADA. 1989:119:298-304.
7. Buege JA, Aust SD. Microsomal lipid peroxidation. Methods Enzymol. 1978:52:302-310.
8. Goldring CE, Rice-Evans CA, Burdon RH. Alpha tocopherol uptake and its influence on cell proliferation and lipid peroxidation in transformed and nontransformed baby hamster kidney cells. Arch. Biochem.Biophys.1993:303:429.
9. Guven Y, Unur M, Bektas K, Uslu E, Belce A, Demirez E, Can S. Salivary malondialdehyde levels in patients with oral leukoplakia. Tur. J Med.Sci.2005: 35:329-32.
10. Panjamurthy K, Manoharan S, Ramachandran CR.Lipid Peroxidation and oxidation status in patients with Peridontitis. Cell Mol. Biol. Lett. 2005:10:255-64.
11. Halliwell B. Antioxidants in human health and disease. Ann. Rev. Nutr. 1996:16:33-50.
12. Moore S, Calder KAC, Miller NJ, Rice-Evans CA. Antioxidant activity of saliva and periodontal disease. Free Radic. Res. 1994:21:417-25.
13. Xiao Yan Li, Zi Chuan Zhang. Assessement of Serum Malondialaldehyde, Uric acid, Vitamin C and E levels in patients with recurrent apathous stomatitis.J Dent Sci 2016 Aug 9;11(4):401–404.
14. Tugrul S., Koçyiğit A., Doğan R. Total antioxidant status and oxidative stress in recurrent aphthous stomatitis. Int J Dermatol. 2016;55:e130–e135. doi: 10.1111/ijd.13101. 
15. Wei Liu,Daoyu Guo. Oxidative stress in periodontitis and application of antioxidants in treatment:a narrative review.Front Physiol 2025https://doi.org/10.3389/fphys.2025.1485367.