Examination shall be made in writing in all theoretical subjects. Both theoretical and practical examinations shall be of a character to give a fair test of the qualifications of the applicant to practice dentistry. The examination papers and all grading thereon, and the grading of the practical work, shall be deemed public documents, and preserved for a period of not less than 2 years after the Department shall have made and published its decisions thereon. All examinations shall be conducted or authorized under fair and wholly impartial methods.