Except as provided in section 20-126k, each applicant for a license to practice dental hygiene shall be examined through written and practical examinations by the Department of Public Health, as to his professional knowledge and skill before such license is granted. All examinations shall be given at least once per year and at other times prescribed by the department. Such examination shall be conducted in the English language. The Commissioner of Public Health may accept and approve, in lieu of the written examination required in this section, the results of a written examination given by the Joint Commission on National Dental Examinations or comparable national examinations subject to such conditions as said commissioner may prescribe; and said commissioner may accept and approve, in lieu of the practical examination required in this section, the results of practical examinations given by regional testing agencies subject to such conditions as the Department of Public Health may prescribe. Passing scores shall be prescribed by the Department of Public Health. Said department shall grant licenses to such applicants as are qualified.