Teething: Teething is the emergence of the primary (baby) teeth through a baby or child's gums. Teething usually begins between four and seven months of age. While the lower central bottom teeth (central incisors) are normally the first primary teeth to erupt, the teething process can vary among individual babies. Normally, all 20 of the primary teeth are present by the time a child reaches age three. Teething can be associated with mild pain and other symptoms including excessive drooling, fussiness, disrupted sleep, and slightly elevated body temperature.