TABLE 2.

The heightened and lowered oral microbiota in Parkinson’s disease.

No.	Studies	Outcomes	References
1	This study investigates if there is a link between oral and nasal microbiota with parkinson’s disease	• Parkinson’s disease patients exhibited a higher prevalence of the Prevotellaceae family compared to the control group • Additionally, there was an elevated occurrence of the Prevotella genus in association with a decline in oral hygiene • Furthermore, Parkinson’s disease patients displayed an increased presence of Moryella and Erysipelotrichaceae	Pereira et al. (2017)
2	This study examines which biomarker that is sensitive and specific in change of oral microbiome in parkinson’s disease	• Parkinson’s disease patients show an elevated presence of Bifidobacteriaceae and Lactobacillaceae • The Enterobacteriaceae family is reduced and there are alterations in the abundance of the Bacillus genus in Parkinson’s disease patients • Parkinson’s disease is associated with an increased occurrence of the Saccharomycetaceae family, including Candida and Saccharomyces cerevisiae • The Acidaminococcaceae family is elevated and there are changes in the abundance of the Flavobacteriaceae family in Parkinson’s disease • The early stage of Parkinson’s disease is characterized by an increase in the Rhodococcus genus	Mihaila et al. (2019)
3	This study explores the composition of oral microbiota and level of oral inflammation in parkinson’s disease patients	• Parkinson’s disease patients exhibit elevated levels of Streptococcus mutans, Veillonella, Lactobacillaceae, Scardovia, Kingella oralis, Negativicutes, Prevotella, and Firmicutes in their oral microbiome • The Prevotellaceae family (specifically, Aloprevotella AM420222 s, Alloprevotella PAC001345 s, Prevotella PAC001346 s, and Prevotella histicola) experienced an increase in bacteria • Parkinson’s disease patients showed a drop in the SR1 phylum	Fleury et al. (2021)
4	This study analyses the impact of poor oral health, poor oral hygiene, and dysphagia status on the oral microbiota composition of parkinson’s disease patients	• There was an increase in Streptococcus pneumoniae and Lactobacillus sp. in Parkinson’s disease patients	Rozas et al. (2021)