Ask The Experts

When should new teeth emerge?

Q My eight-year-old son lost one of his upper central incisor milk teeth about four months ago and there is still no sign of the new tooth.

The permanent tooth for his other front upper central milk incisor, which fell out earlier, has already erupted.

Is it normal for a permanent tooth to take so long to erupt?

A There is a large variation in actual tooth eruption timings.

On average, the upper adult central incisor erupts when a child is seven years old.

It is not uncommon to wait up to six months for the new adult successor to emerge after a baby tooth falls out naturally.

However, at four months, the upper limit of your child's six-month window is approaching. Watchful waiting may not be the only approach you would like to take.

You may want to visit your paediatric dentist to rule out any dental issues that may be contributing to the tooth's delayed emergence.

If any issues are present, early detection and timely management will give your child the best results. One example is the presence of a supernumerary tooth (extra tooth) in the jaw. This occurs in approximately 3 per cent to 4 per cent of children.

Supernumerary teeth, called mesiodens, are commonly found near the adult central incisors and can block the central incisor's path of eruption, causing them to emerge after some delay, erupt out of position, or even completely fail to erupt. In such cases, removal of the supernumerary tooth or teeth will be warranted.

While mesiodens are often detected in routine radiographs, the timing to remove such teeth is important. There is a need to balance the risk between damaging the developing permanent teeth and yet allow the adult incisors to spontaneously erupt into good positions.

Your paediatric dentist would be the best person to advise on this. He or she will also discuss your child's dental history with you to exclude other possible reasons for the delayed eruption.

For example, previous dental injuries or infections sustained by his baby incisors could have an impact on the timely eruption of the adult incisor.

While I have listed the more common reasons that may explain a tooth's delayed eruption, specific advice tailored to your child's condition can be given only after a comprehensive dental examination or other investigations, such as dental radiographs. 

DR TABITHA CHNG

Associate consultant in the paediatric dentistry unit, department of restorative dentistry, National Dental Centre Singapore

A version of this article appeared in the print edition of The Straits Times on January 26, 2016, with the headline 'When should new teeth emerge?'. Print Edition | Subscribe