When children enter the tooth transition period, their deciduous teeth will loosen due to the resorption of the roots and will sequentially fall off. The permanent teeth will gradually erupt into the space left by the deciduous teeth. Tooth transition period starts approximately at the age of 6, and ends at around the age of 12 or 13.   There are altogether 32 permanent teeth. Since dentine is usually slightly yellowish, and the enamel in permanent teeth is more transparent than that of deciduous teeth, the colour of permanent teeth is more yellowish than deciduous teeth. As the thickness of dentine grows as a person ages, the teeth will also become more yellowish.   Permanent Teeth Eruption Time Central Incisor 6 to 8 years Lateral Incisor 61/2 to 9 years Canine 81/2 to 121/2 years First Premolar 8 to 12 years Second Premolar 81/2 to 13 years First Molar 5 to 7 years Second Molar 10 to 14 years Third Molar (Wisdom tooth) 17 to 25 years