The timing of eruption of the deciduous incisors (6-12 months) coincides with the diminution of the circulating maternal humoral immunity conferred via the placenta, and the establishment of the child's own humoral immunity. Most children of this age are susceptible to a myriad of relatively minor infections.

The study by King et al. found that 9 out of 20 infants reported to be 'teething' by one of their parents produced an oral swab positive for herpes simplex virus (HSV) and hence the possibility that certain teething symptoms (fever, irritability and eating disturbance) resulted from an undiagnosed primary herpetic infection. (11) An undiagnosed concurrent primary herpetic infection could be responsible for the symptoms of fever, irritability and appetite loss. The formation of a gingival crevice around a newly erupting tooth could act as a portal of entry for herpes viruses. (11)

The symptoms of elevated temperature and facial rash could also be due to infection with the Human Herpes Virus 6 (HHV-6), which is ubiquitous among infants of teething age. The fact is several of the features attributed to teething can be explained by alternative non-teething etiologies, but still many parents will testify that their children are teething.

Pain is reported as a common feature of teething by parents. It is not the tooth which contributes, but the dental follicle which is a rich source of eicosanoids, cytokines and growth factors resulting in a localized inflammatory response and pain. Lay people state that 'the tooth coming through the bone' is responsible. There is no evidence to support this, and indeed, the etiology of the teething symptoms is caused by one of the many childhood illnesses.