Quantitative Polymerase Chain Reaction Analysis of Cariogenic Streptococcus mutans in Saliva of Oral and Laryngeal Cancer Patients Undergoing Radiotherapy: A Clinical Study

CONTEXT: Radiotherapy leads to radiation-induced caries. There is limited knowledge about the quantification of cariogenic bacteria in the saliva of irradiated cancer patients. OBJECTIVE: The aim of this study is to check salivary pH, flow rate, and the assessment of Streptococcus mutans in the saliva of irradiated oral and laryngeal cancer patients using quantitative real-time polymerase chain reaction (qRT-PCR). SETTINGS AND DESIGN: This was time-bound study which consisted of 26 cancer patients undergoing radiotherapy (13-oral cancer 13-laryngeal cancer). SUBJECTS AND METHODS: Resting saliva samples were gathered from oral (Group-I) and laryngeal (Group-II) cancer patients immediately before radiotherapy and after completion of radiotherapy (dose-60 Gy). pH of saliva and the salivary flow rate was measured. S. mutans were analyzed using qRT PCR. STATISTICAL ANALYSIS USED: Data were analyzed using SPSS software 20. Paired t-test was used to evaluate salivary pH, flow rate, and amount of S. mutans pre- and post-radiotherapy for Group I and II. Independent t-test was used to compare salivary pH, flow rate, and S. mutans pre- and post-radiotherapy between Group I and II. RESULTS: Salivary pH and flow rate significantly reduced postradiotherapy in oral and laryngeal cancer patients (P < 0.001). The amount of S. mutans statistically increased postradiotherapy in oral cancer patients (P = 0.001). While S. mutans count was statistically insignificant in laryngeal cancer patients (P = 0.091). There was a significant increase in the amount of S. mutans in Group I when compared with Group II (P = 0.002). CONCLUSION: Amount of S. mutans increased postradiotherapy in oral cancer patients. While the salivary pH and salivary flow rate reduced postradiotherapy.