Acknowledgment The author acknowledges the contribution to this chapter by the previous author, Dr. John S. Greenspan. Diseases of the Teeth and Periodontal Structures Tooth and Periodontal Structure Tooth formation begins during the sixth week of embryonic life and continues through the first 17 years of age. Tooth development begins in utero and continues until after the tooth erupts. Normally all 20 deciduous teeth have erupted by age 3 and have been shed by age 13. Permanent teeth, eventually totaling 32, begin to erupt by age 6 and have completely erupted by age 14, though third molars (wisdom teeth) may.
