Table 1 The surveys or experiments about Parkinson’s disease and oral diseases

Verhoeff et al.¹²

63 studies

Prevalence of self-reported xerostomia and drooling

534 participants with Parkinson’s disease were involved in the objective studies, and 11 670 participants were included in the subjective studies. The objective and subjective study participants had a mean age of 67 ± 7 and 62 ± 17 years, respectively.

Xerostomia

Parkinsonians’ probability of suffering by xerostomia higher than healthy people. Patients with Parkinson’s disease have a lower salivary flow rate and higher prevalence of both xerostomia and drooling.

Yilmaz et al.²⁰

60 patients and 20 healthy individuals

Recording and comparing the periodontal status, collecting serum, saliva, and gingival revicular fluid samples to judge the level of PD

60 patients with Stage III, Grade B periodontitis and 20 healthy individuals as controls.

Periodontitis

There is a high positive correlation between PD and periodontitis.

Minervini et al.³⁴

3 studies

Prevalence of TMDs

All together they comprised a total of 55 828 subjects, out of which 12 629 were affected by PD or Parkinsonism, and the remaining 43 199 were non-PD subjects matched for age and sex.

Temporomandibular disorders

There was a higher TMD prevalence in PD subjects compared to non-PD subjects.

Weintraub et al.³⁷

315 patients

Observational data from Parkinson’s Progression Markers Initiative annual visits was used to evaluate prevalence, correlates, and treatment of 10 neuropsychiatric symptoms and cognitive impairment in Parkinson disease participants and matched healthy controls.

Eight neuropsychiatric symptoms studied increased in absolute prevalence by 6.2–20.9% at year 5 relative to baseline, and cognitive impairment increased by 2.7–6.2%.

Neuropsychiatric disorders/ cognitive impairment

PD patients’ probability of cognitive impairment is higher than healthy people obviously.

Li et al.⁶²

Data from the UK Biobank, summary statistics from previous genome-wide association studies.

Objective assessments (Cox proportional hazards regression analysis, extensive genetic analyses); About the relevancy between systemic inflammation with CRP IL-6 as symbols and PD.

NA

NA

There is a negatively correlated between CRP and PD; PD and IL-6 haven’t apparent correlation.

Muñoz-Delgado et al.⁶⁴

555 patients

Clinical features, the peripheral immune profile, and striatal

The patients with different levels of PD (including 211 people in primary-cohort, 344 people in PPMI-cohort).

Systemic inflammation

There is a relationship between systemic inflammation and dopaminergic degeneration in patients with PD.

Zhang et al.¹¹⁸

Male C57BL/6J mice aged 8–10 wk

Blood Zn concentrations; degeneration of dopaminergic neurons; Open field test, rotarod test, immunohistochemistry, and RNA sequencing were performed after 13 wk.

The mice were categorized as four types: Saline-ZnA、Saline-ZnD、MPTP-ZnA and MPTP-ZnD

Circulating Zn concentrations

Zn deficiency aggravates movement disorders in PD mice, appropriate Zn supplementation may be beneficial for PD.