Salivary microbial profiles across periodontal severity stage according to the 2018 AAP/EFP classifications: a cross-sectional study

Background Periodontitis is a chronic inflammatory disease characterized by progressive destruction of the periodontal supporting tissues and is strongly associated with shifts in the oral microbiota. Saliva has emerged as a promising diagnostic fluid; however, few studies have analyzed its microbial composition at the species level according to the 2018 American Academy of Periodontology/European Federation of Periodontology (AAP/EFP) classification of periodontal diseases. Objectives To characterize salivary microbial profiles in a systemically healthy Mexican population across different stages of periodontitis according to the AAP/EFP 2018 classification system, and to evaluate sociodemographic, anthropometric, and clinical characteristics as potential risk factors for periodontitis. Methods A cross-sectional study was conducted by analyzing 133 adults classified in four groups: periodontally healthy ( n = 33 ), gingivitis ( n = 34 ), stage I–II periodontitis ( n = 18 ), or stage III–IV periodontitis ( n = 48 ). Unstimulated saliva from all participants was sampled and analyzed for 40 bacterial species using Checkerboard, a DNA–DNA hybridization technique. Microbial levels, prevalence, and proportions were compared among groups. Ordinal logistic regression was then used to identify independent predictors of disease severity. Results The Porphyromonas gingivalis and Tannerella forsythia bacteria showed significantly higher levels in advanced periodontitis ( p < 0.001 ). Bacteria from the Orange complex , such as Campylobacter rectus and Campylobacter showae , also increased with disease severity. In contrast, commensal species, notably Gemella morbillorum, were diminished. Ordinal logistic regression identified age (OR = 1.10, p < 0.001), the presence of dental biofilm (OR = 1.03, p = 0.005), and higher counts of the Aggregatibacter actinomycetemcomitans (OR = 1.19, p = 0.005), and P. gingivalis (OR = 1.21, p < 0.001) microbial species, as positive predictors of periodontitis . Conclusions The salivary microbiota shows distinct abundance signatures across periodontal severity stages. These patterns are characterized by an enrichment of pathogenic microbial complexes and depletion of commensal species. This aligns with current frameworks placing dysbiosis as a relevant risk factor for periodontitis. These findings also support saliva as a feasible matrix for periodontal screening and risk stratification. This may result particularly useful in resource-limited clinical laboratory settings.