Supragingival and subgingival microbiota from patients with poor oral hygiene submitted to radiotherapy for head and neck cancer treatment

Objective: This case-control study aimed to evaluate the effects of conventional radiotherapy (RT) on the prevalence and populations of oral microorganisms in head and neck cancer patients who did not receive adequate preventive dental care. It was hypothesized that side effects of radiotherapy could be associated with radiation dose, microbiological aspects, and socioeconomic conditions of the patients. Design: Twenty-eight dentate patients with head and neck cancer submitted to RT were included in the study. Radiation dose received varied from 4320 to 7020 cGy. Patients with the same demographic and health conditions, but no history of cancer or antineoplastic treatment were used as controls. Clinical examinations were carried out before RT, 15-22 days after starting RT, immediately after and 6 months after RT. Supra and sub gingival biofilms were collected and cultivated onto selective and non-selective media. Isolates were identified by biochemical and physiological characteristics. Stimulated and unstimulated salivary flow rate and saliva buffer capacity were also determined. Results: Mucositis, dermatitis, xerostomia, dysgeusia, dysphagia and candidiasis were common after starting RT and during the treatment period. Xerostomia was followed by a decrease in salivary pH and buffer capacity, which showed association with the increase of cariogenic cocci and yeast populations, which were also associated with deterioration of hygiene. Candida and family Enterobacteriaceae showed increased prevalence with RT, and were associated with the occurrence of mucositis and xerostomia. Conclusions: Modifications in oral biofilms of irradiated patients showed association with xerostomia and hygiene conditions, which reinforces the necessity of improving patient compliance to oral health care programs.