Kittens typically begin teething around 3 to 4 months of age, when their baby teeth start to be replaced by permanent teeth. Teething usually lasts until the kitten is about 8 months old, by which time all of its baby teeth should have been replaced by permanent teeth.

During the teething period, a kitten's baby teeth will gradually loosen and fall out, and new teeth will gradually grow in. This process may cause pain and discomfort in the kitten's teeth. Therefore, it is important to provide the kitten with sufficient nutrition during this time, especially foods rich in calcium and phosphorus, to help with tooth growth.