Background: The number of people with dementia and natural dentition is growing. As dementia progresses, the degree of self-care decreases and the risk of oral health problems and orofacial pain increases. Objectives: To examine and compare the presence of orofacial pain and its potential causes in older people with Mild Cognitive Impairment (MCI) or dementia. Methods: In this cross-sectional observational study, the presence of orofacial pain and its potential causes was studied in 348 participants with MCI or dementia with all levels of cognitive impairment in two outpatient memory clinics and ten nursing homes. Results: Orofacial pain was reported by 25.7% of the 179 participants who were considered to present a reliable pain self-report (Mini-Mental State Examination score ≥14 points), while it could not be determined in people with more severe cognitive impairment. The oral health examination of the 348 participants indicated that potential painful conditions, such as coronal caries, root caries, tooth root remnants or ulcers were present in 50.3%. There was a significant correlation between the level of cognitive impairment and the number of teeth, r = 0.185, P = 0.003, teeth with coronal caries, r = −0.238, P < 0.001, and the number of tooth root remnants, r = −0.229, P = 0.004, after adjusting for age. Conclusions: This study indicated that orofacial pain and its potential causes were frequently present in participants with MCI or dementia. Therefore, a regular oral examination by (oral) healthcare providers in people with MCI or dementia remains imperative, even if no pain is reported.