The orthodontist should have a good information of tooth emergence of the patient. When the upper permanent canine teeth and lower mandibular premolars have erupted sufficiently, fixed appliance can be started. The dental age chart of Dr. Hurme serves as a guide in the assessment and should not be followed strictly according to the various ages. The guide of the chart is to give the orthodontist an idea of tooth emergence pattern or eruption sequence prediction in the oral cavity.
Tooth emergence gives individual variations even within the same population. Exogenous factors such as systemic diseases, infection, injury, extraction of teeth, crowding, difficiency of vitamin A or D, hypothyroidism and sickness may affect tooth eruption.