There are 269 dental assistant training programs approved by the Commission on Dental Accreditation. While diploma courses can take up to 12 months, associate degree courses are usually 2 years in duration. A high school diploma will be required to enter these programs. These courses will involve class time, lab practicals and also on-the-job training in a dental clinic or office. Working directly with a dentist is the best way to hone your dentistry skills.