Dentists have been supposed to be among the healthcare workers at greatest risk of SARS-CoV-2 infection. However, scant data are available on the issue. The aim of this study is to quantify the SARS-CoV-2 antibody prevalence and determinants in a sample of dentists, dental hygienists, and other personnel employed among the dental staff in Lombardy region. We used an accurate rapid diagnostic test kit detecting immunoglobulins (Ig) in 504 adults. Of the 499 participants who obtained a valid antibody test, 54 (10.8%) had a SARS-CoV-2 positive test (0.4% IgM+, 1.8% both IgM+ and IgG+, and 8.6% IgG+). A statistically significant association with infection was found for geographic area (compared to Milan, adjusted odds ratio was 2.79, 95% confidence interval, CI: 1.01–7.68 for eastern and 2.82, 95% CI: 1.34–5.94, for southern Lombardy). The clinical staff did not result positive to SARS-CoV-2 more frequently than the administrative staff. This is the first study using antibody test in the dental staff personnel. It shows that the prevalence of SARS-CoV-2 infection in Lombardy region was around 10%, in line with estimates on other healthcare professionals. Despite the close physical contact with the patient, dentists have been able to scrupulously manage and effectively use protective devices.