The first permanent teeth to emerge are usually the maxillary and mandibular first molars. These molars will erupt behind the most posterior primary teeth - primary second molars. The permanent molars are referred to by their anticipated age of eruption. The first molars are called the six-year molars, and the second molars are referred to as the twelve-year molars.
The first permanent molars usually erupt between 5.5 and 7 years of age. Their eruption may be accompanied by or preceded by the exfoliation of the mandibular central incisors. Between the ages of 6 and 7, the mandibular permanent incisors erupt with the maxillary incisors following at ages 7 through 9.
The anterior permanent teeth develop behind (lingual or palatal to) the primary teeth, and the permanent premolars (bicuspids) develop beneath and between the roots of the primary molars they replace. Often a "bulge" on the gingiva can be seen prior to the eruption of a permanent incisor or canine. The bulge is the crown of the erupting tooth.
Teething is a natural process that occurs as the tooth penetrates the gum. It may cause increased drooling and the desire to bite or chew on things. There may be mild pain associated with teething, but there is no evidence that high fevers, diarrhea, facial rashes, or sleep problems are caused by teething.