<prompt> True about dentition are all exceptHypothyroidism causes delayed dentitionPremolar is not seen in primary dentitionThird molar is last to appear in secondary dentitionCanine is the first in primary dentition  <response>: The first tooth to erupt in primary dentition is the lower central incisor at 6-10 yrs of age, and in upper jaw at the age of 8-12 yrs. Whilst the canine in primary dentition appears at the age of 16-22 yrs, in the upper jaw. Ref: Ghai, 9th edition, Table 2.2. 