Short-Term Effects of Comprehensive Periodontal Initial Therapy on Subgingival Microbiota in Nasopharyngeal Carcinoma Patients Undergoing Radiotherapy: A Pilot Randomised Controlled Trial

OBJECTIVE: This pilot randomised controlled trial (RCT) compared the effects of supragingival scaling versus comprehensive periodontal initial therapy performed before radiotherapy on periodontal indices and the subgingival microbiota in patients with nasopharyngeal carcinoma (NPC) and periodontitis. The study aimed to investigate the impact of periodontal initial therapy on periodontal health in patients undergoing radiotherapy, providing evidence for preradiotherapy oral health management. METHODS: Twelve NPC patients with periodontitis were enrolled and randomly assigned to control or test groups. The control group received supragingival scaling before radiotherapy, the test group received comprehensive periodontal initial therapy. Clinical periodontal indices (probing depth [PD], attachment loss [CAL], bleeding index, bleeding on probing, and plaque index and subgingival plaque samples were collected from both groups before treatment and at the end of radiotherapy. The subgingival microbiota was analysed using 16S rRNA sequencing. Changes in indices and microbial community structure after radiotherapy were compared between groups. RESULTS: Between-group differences in the changes of full-mouth mean PD and CAL were significant (P < .05). Microbial analysis revealed that 6 phyla (including Firmicutes and Bacteroidetes) dominated >90% of the microbiota, while 8 genera (including Fusobacterium, Prevotella, and Treponema) accounted for >70%. Alpha diversity decreased significantly in the test group postradiotherapy (P < .05), and beta diversity showed significant microbial structure changes (P < .05). Post-treatment, opportunistic pathogens (Haemophilus, Veillonella) were significantly higher in controls. Bacteria (Lactobacillus, Lautropia) increased in the test group but decreased in controls after treatment. CONCLUSION: In this pilot RCT, comprehensive periodontal initial therapy before radiotherapy was associated with favourable short-term changes in selected periodontal parameters and subgingival microbial profiles than supragingival scaling alone in NPC patients with periodontitis. Given the small sample size and potential microbiome-related confounders, these findings should be interpreted as preliminary and require confirmation in adequately powered multicentre trials.