Abstract
Periodontal diseases in pediatric subjects represent a challenging and relatively underexplored area compared to the extensive data available about periodontal diseases in adults. The present narrative review aims to explore the periodontal status and the related subgingival and/or salivary microbial profiles in pediatric subjects (≤18 years), focusing also on the state of health or systemic diseases. In healthy periodontium, early colonizers, such as Streptococcus and Actinomyces spp., dominate the subgingival microbiota, supporting an eubiosis state. Low levels of Candida albicans and latent Herpesviridae may be detected. In gingivitis, the microbial profile shifts towards more pathogenic species, including Prevotella intermedia and Fusobacterium nucleatum. In necrotizing gingivitis, typically affecting systemically compromised children, the microbial profile is characterized by spirochetes, Fusobacterium, and Prevotella intermedia. Viral coinfections-especially with HSV, CMV, and EBV-are more frequently detected. In periodontitis, the microbiota was dominated by red complex pathogens along with Aggregatibacter actinomycetemcomitans in the aggressive forms, especially in systemically compromised children, as Herpesviridae reactivation and co-infections. Fungal involvement is less well characterized; Candida albicans may be present, particularly in cases of severe immune suppression. Nevertheless, the lack of pediatric longitudinal studies investigating periodontal disease progression after periodontal treatment and related changes in microbiological composition limited the understanding and exploration of the oral microbiota over time.