Salivary microbiota profile in adult and children population according to active dentin caries: a metagenomic preliminary analysis

Nuria Tamayo-Estebaranz^1,2Carolina Muñoz-Gonzalez³Ana María Gil-Valcárcel⁴Paula Calvo López-Dávalos³ANDREA MARTÍN-VACAS^2,4*MARTA PAZ CORTES⁴Juan Manuel Aragoneses^4,5

• ¹Programa de Doctorado en Ciencias de la Salud, Departamento de Medicina y Especialidades Médicas, Facultad de Medicina y Ciencias de la Salud, Universidad de Alcalá, Alcalá de Henares, Spain
• ²Alfonso X el Sabio University, Villanueva de la Cañada, Madrid, Spain
• ³Instituto de Investigación en Ciencias de la Alimentación, CSIC-UAM, Madrid, Spain
• ⁴Faculty of Dentistry, Alfonso X El Sabio University, 28691 Villanueva de la Cañada, Spain., Villanueva de la Cañada, Madrid, Spain
• ⁵University Federico Henriquez y Carvajal, Santo Domingo Oeste, Distrito Nacional, Dominican Republic

Objectives: The aim of this study was to investigate the relationship between active dentin caries (ADC), salivary biochemical parameters, and salivary microbiota composition in Spanish children and adults.Methods: Saliva samples were collected from 80 subjects (40 adults and 40 children) divided between ADC and non-ADC. Salivary biochemical determination was performed by analysing total protein content (TPC) and total antioxidant activity (TAC) in saliva supernatants. DNA was obtained using the Bacterial DNA kit and analysed with the Illumina NextSeq platform. Alpha diversity and beta diversity were analysed. In addition, Linear Discriminant Analysis Effect Size (LEfSe) was used to identify differential taxa between groups. All statistical analysis were performed with a 95% confidence level (p <0.05).Results: No significant associations were found between ADC and salivary biochemical markers in either the adult or pediatric age group, suggesting that these parameters alone may not sufficiently reflect cariogenic activity. Microbiota analysis at the phylum level did not show significant correlations with ADC; however, distinct associations appeared at the genus and species levels. In adults, several genera (Corynebacterium, Porphyromonas, Tannerella, Catonella, Filifactor, Parvimonas, and Dialister) were positively associated with ADC, reflecting a shift towards a dysbiotic microbiome composition that overlaps with periodontal and endodontic pathologies. Conversely, Haemophilus was negatively correlated with ADC, potentially indicating a protective role. At the species level, a positive correlation with ADC was found with Porphyromonas gingivalis, Porphyromonas endodontalis, Peptostreptococcus stomatis, Leptotrichia buccalis, Prevotella oris, or Corynebacterium matruchotii in the adult population. In children, microbial associations with caries were more limited, with Scardovia, positively correlated with ADC, and P. stomatis showing a negative association. Interestingly, P. stomatis exhibited opposite correlations in adults and children, possibly reflecting age-specific ecological roles. No significant differences in alpha or beta diversity were found either in adults or children participants.Conclusions: Overall, these findings highlight a stronger and more diverse association between salivary microbiota and caries in adults compared to children. These results underscore the importance of agespecific microbial signatures in the aetiology of dental caries.The obtained differences suggest that caries development in adults may involve broader dysbiosis involving proteolytic and anaerobic organisms in addition to acidogenic species.