Oral microbiome dysbiosis of Porphyromonas gingivalis in oral leukoplakia, oral squamous cell carcinoma and radiation-induced oral mucositis: a qPCR-based cross-sectional study

Background Porphyromonas gingivalis is a key periodontal pathogen increasingly implicated in periodontitis and oral carcinogenesis. Among its virulence determinants, fimbriae encoded by the fimA gene exhibit pathogenic potential. While previous studies have mainly focused on fimA II and IV genotypes in periodontitis, limited data exist on the role of fimA I in oral squamous cell carcinoma (OSCC), and radiation-induced oral mucositis (RIOM). The present study aimed to evaluate the relative abundance of the fimA I genotype across different oral disease conditions and to assess its potential role as a biomarker of disease associated microbial dysbiosis.Methods In total, 96 oral swab samples were collected from six groups: healthy nonsmokers, healthy smokers, periodontitis, OL, OSCC, and RIOM. Quantitative real-time PCR was performed to assess the relative abundance of the genotype using genotype-specific primers.Results FimA I expression was highest in RIOM, followed by OSCC and periodontitis, and lowest in OL and healthy groups. A statistically significant increase was observed in RIOM and OSCC compared to controls (p < 0.05).Conclusion The fimA I genotype shows higher abundance in OSCC and RIOM, suggesting its potential role as a microbial biomarker in disease monitoring and therapeutic targeting.