In this chapter, the following terms have the meanings indicated. Terms Defined. Active Practice. “Active practice” with respect to dentistry means the practice of dentistry for at least 500 hours within the 36-month period preceding expiration of a license. “Active practice” with respect to dental hygiene means the practice of dental hygiene for at least 150 hours within the 36-month period preceding expiration of a license. “Approved school” means a school determined by the Commission on Dental Accreditation to have met minimum standards. “Board” means the Board of Dental Examiners.