Most dentists work 4 or 5 days a week. Some work evenings and weekends to meet their patients’ needs. The number of hours worked varies greatly among dentists. Most full-time dentists work between 35 and 40 hours a week. However, others, especially those who are trying to establish a new practice, work more. Also, experienced dentists often work fewer hours. It is common for dentists to continue in part-time practice well beyond the usual retirement age.
Source: Bureau of Labor Statistics, U.S. Department of Labor, Occupational Outlook Handbook, 2008-09 Edition