Background and Objectives: Infection control practices in dentistry should be continuously evaluated. The aim of the present study was to assess the knowledge of dental students from Iași, Romania about infection control in the dental office. Materials and Methods: Dental students and resident dentists attending the “Grigore T. Popa” University of Medicine and Pharmacy in Iași were randomly selected in accordance with ethical guidelines, and a cross-sectional, questionnaire-based online study was conducted. The questionnaire included 21 items about infection control in dentistry. A descriptive statistical analysis was performed, and the chi-square test was used for data comparison, with a cutoff point of 0.05 for statistical significance. Results: The study sample included 150 subjects (75.3% female and 24.7% male) with a mean age of 25.71 ± 4.54 years. Mode of infection transmission was known by 74% of the subjects, and 76% were aware of standard precautions, with significant differences by the year of study (p = 0.012, r = 0.002). A percentage of 20% of subjects knew the means of transmission of the hepatitis B virus (HBV) (p = 0.032, r = 0.166). Most of the subjects were not vaccinated against HBV (p = 0.002, r = −0.274). Notions of high-level disinfection and sterilization were confused by 19.5% of the subjects. Only 22% of the subjects knew the correct processing of handpieces (p = 0.048, r = −0.071). The sources of information were diverse for 64.66% of the respondents, while 31.33% of them used courses and seminars only. Conclusions: There is a need for improvement in the level of knowledge on infection control for both dental students and residents.