He then entered Harvard University School of Dentistry , graduating with the degree of D.M.D. in 1873 , at the age of 21 years .
William studied dentistry as an apprentice to Dr. Kidder of Lawrence , for three years .
William then entered Harvard University School of Dentistry , graduating with the degree of D.M.D. in 1873 , at the age of 21 years .
William studied dentistry as an apprentice to Dr. Kidder of Lawrence , for three years .