Salivary Microbial Profiles Across Periodontal Severity Stages According to the 2018 AAP/EFP Classifications: A Cross‐Sectional Study

Background: Periodontitis is a chronic inflammatory disease characterized by progressive destruction of periodontal supporting tissues, 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 in the context of the 2018 classification of periodontal diseases. Objectives: To characterize the salivary microbial profiles in a systemically healthy Mexican population with different stages of periodontitis according to the 2018 AAP/EFP (American Academy of Periodontology/ European Federation of Periodontology) classification, and to evaluate sociodemographic, an-thropometric parameters and clinical characteristics as possible risk factors. Methods: A cross-sectional study was conducted in 138 adults classified as periodontal health (n = 33), gingivitis (n = 34), stage I-II periodontitis (n = 18), or stage III-IV periodontitis (n = 53). Unstimulated saliva samples were analyzed for 40 bacterial species using Checkerboard DNA–DNA hybridization technique. Microbial levels, prevalence, and proportions were compared, and multivariate ordinal logistic regression was used to identify independent predictors of disease severity. Results: Porphyromonas gingivalis and Tannerella forsythia exhibited significantly higher levels in advanced periodontitis (p< 0.001). Orange complex bacteria, including Campylobacter rectus and Campylobacter showae, also increased with severity, while commensals such as Gemella morbillorum and Streptococcus sanguinis de-creased. Ordinal logistic regression identified age (OR=1.10, p< 0.001), dental plaque (OR=1.03, p=0.008), C. rectus (OR=1.33, p=0.043), and P. gingivalis (OR=1.22, p< 0.001) as positive predictors of periodontitis. Conclusions: The salivary microbiota exhibits distinct microbial signatures by periodontal severity, with enrichment of pathogenic complexes and depletion of commensals. These findings support saliva as a feasible matrix for screening and prognosis, particularly in resource-limited laboratory clinical settings.