Background: Due to a dearth of information on preventive and supportive oral care for people with Down Syndrome (PDS) in Germany, caregivers of PDS were surveyed on the topic. Methods: An anonymized questionnaire was sent to the 610 members of the German Down Syndrome Association. The study was approved by the ethics committee of Witten/Herdecke University (# 165/2017). Results: The parents/caregivers of 207 PDS responded. These PDS were between 1 and 55 years old (mean age 24.4 years) and included 111 males and 96 females. At their first dental appointment, 40.7% (n = 82) had been younger than three years. Although 78.3% (n = 162) tooth brushed twice daily, only 30.9% (n = 64) brushed for 2–3 min; 84.0% (n = 135) did not use other dental hygiene products apart from toothbrushes. Age-specific differences were found: Although only 30.8% (n = 12) of PDS < 18 years (n = 39) independently performed dental self-care; this was 67.3% (n = 113) for PDS ≥ 18 years (n = 168). A statistically significant (p < 0.001; Chi-Square-Test) difference in toothbrush preferences emerged: While PDS < 18 years mainly used manual toothbrushes, PDS ≥ 18 years preferred electric toothbrushes. In contrast to 72.6% of PDS ≥ 18 years, only 51.3% of PDS < 18 years accepted most types of toothpaste. Conclusions: Age-dependent differences in tooth brushing behaviour became evident within the group of PDS in Germany. Hence, better age-specific, inter-professional dental prophylaxis concepts need to be developed and offered for all age groups of PDS. These concepts should include personalized check-up intervals and hands-on instruction in dental hygiene procedures by dental practitioners.