Background: People with intellectual disabilities (IDs) may be at increased risk of developing periodontal diseases and dental caries due to poor oral hygiene. Our aim was to investigate motor proficiency factors associated with presence of visible plaque and gingival bleeding in people with IDs. We were particularly interested in the level of dependence, manual coordination and fine manual control of people with ID, as well as the level of exhaustion of the primary caregiver. Methods: In this cross-sectional study, 299 people with ID were evaluated for oral hygiene using the simplified Visible Plaque Index and for gum inflammation using the Gingival Bleeding Index. The Bruininks-Oseretsky Motor Proficiency Test assessed motor proficiency through fine manual control (fine motor integration and fine motor precision) and manual coordination (manual dexterity and upper limb coordination). The level of dependence was assessed by the Katz dependency index, and the caregiver was tested for exhaustion using the fatigue severity scale. Prevalence ratios [and 95% confidence intervals (CI)] were calculated using crude and adjusted Poisson regression with robust variance. Results: The exhaustion of the caregiver was associated positively to visible plaque [prevalence ratio (PR) = 1.36; 95% CI 1.06–1.65]. For gingival bleeding, people with IDs that had better fine motor integration (PR = 0.49; 95% CI 0.33–0.75) and precision (PR = 0.50; 95% CI 0.26–0.94), as well as manual dexterity (PR = 0.62, 95% CI 0.49–0.77), presented better results. Conclusion: Poor oral hygiene and gum inflammation were associated with motor proficiency of people with IDs and caregivers' exhaustion. Interventions to improve the oral health of people with IDs should take into account such conditions.