<p>The delicate balance of the oral cavity is disrupted by changes in hygiene and diet, leading to caries. The virulence of <i>Streptococcus mutans</i>, a key caries pathogen, is partly explained by its rhamnose-glucose polysaccharide (RGP) and its sucrose-dependent and -independent adhesion mechanisms. Given their role in comorbidities, this study investigates the diversity of <i>S. mutans</i> through analysis of RGP and sucrose-independent adhesion proteins (SpaP, WapA, Cnm, Cbm) in Parkinson’s disease patients. In the PARKIDENT clinical trial, strains were isolated from saliva samples of Parkinson’s patients at baseline and during a follow-up visit. Strains were preanalyzed by multiplex PCR for serotype and collagen-binding proteins, followed by high-throughput sequencing and bioinformatics analysis using RAST® and BLAST®. Phylogenetic analyses and protein modeling were also conducted. Of 40 patients in the Parkident clinical trial, only 24 had <i>Streptococcus mutans</i> strains isolable from salivary swabs. Serotyping revealed that over 80% of the 44 strains isolated were serotype c, in line with prevalence data in the literature. Furthermore, only SpaP types A and B were identified in the strains. The low variability observed for the WapA protein underlines its functional importance. Finally, the <i>cbm</i> gene was not found in any strain, and only 5 strains possessed the <i>cnm</i> gene, all of them serotype c. The study of these 44 <i>Streptococcus mutans</i> strains showed characteristics similar to other populations. Serotype c predominates, with minimal peptide sequence variability in adhesion proteins (SpaP, WapA). Collagen-binding proteins Cnm and Cbm are rare or absent. Further research is essential to better characterize strain distribution in the Parkinson’s-affected population due to <i>S. mutans</i>’ growing role in extra-oral pathologies. Trial registry: ClinicalTrials.gov ID NCT03827551, First submitted: 2019-01-25</p>