between 13 & 33 months old eruption of the first tooth all 20 of their baby teeth between 13 & 33 months old webmd.com losing their teeth complete set of baby teeth growing primary teeth from 6 months to 3 years all 20 of their baby teeth child’s dental development web md first molars child’s oral health webmd.com ages of two and three back molars 6 years Dental Health- Your Child’s Baby Teeth teeth webmd.com WebMD