When I see a kitten for their first post adoption visit, the family often asks me to determine the kitten’s age. Since weight and size are dependent on nutrition, I use teeth instead. Here are the guidelines I use for determining age in kittens: Please note that baby teeth are also called deciduous teeth.
3-4 weeks old-Deciduous incisors are present. These are the little teeth on the front of the upper and lower jaw, between the large canine teeth.
3-4 weeks old-Deciduous canines are present. People often refer to these large teeth as ‘fangs’.
5-6 weeks-deciduous premolars are present. The premolars are the large teeth in the back of the mouth.
8 weeks-All deciduous (baby) teeth are present.
3 -4 months-Permanent incisors erupt
4-5 months-Permanent canine, premolar and molar teeth erupt. Usually, the canines or fangs appear first followed by the premolars and molars.
All permanent teeth should be present by 6 months of age.
Source: -Gorrel, Cecilia. Veterinary Dentistry for the General Practitioner. Saunders 2004, p 30.