Failure of Permanent Teeth to Grow Into the Mouth Part II

Occasionally permanent lower cuspids impact.  Their position can usually be felt by finger pressure against the jawbone under the lip. However, discovering an impaction is more often done by x-ray, and the impaction may lie horizontally along the lower border of the lower jaw, where it cannot be felt.  An orthodontist and oral surgeon need to decide how to handle this problem. Early detection may save the impaction from getting worse and allow the tooth to be brought in with orthodontic treatment.

The most common delayed eruption in the lower jaw is the second bicuspid.   The tooth is missing 1% of the time, and even if present the unerupted tooth is commonly seen on  x-rays to be growing in a backward angle instead of vertically, jamming it into the erupted first permanent molar.  Detection of these problems in children is by x-ray (usually a panorama x-ray).  The need for an x-ray is realized because either the space is too small for the tooth to grow in, or the tooth is too slow to grow in.

 

The lower second bicuspids do not normally grow in until age 12-13.  When a problem is detected earlier (by x-ray or space shortage), have an orthodontist decide whether, if the tooth is missing, to keep the baby tooth, or remove the baby tooth and close the space, or if the tooth is impacting, whether to have an oral surgeon attach a gold chain to it so it can be brought in.  The bicuspids need to have 50% root development before intervening surgically, or else the surgery may inhibit full root development.

If three of the first permanent molars have erupted and the fourth one has not, the unerupted one may be incorrectly erupting under the adjacent second baby molar, instead of behind it. X-rays will show whether the baby tooth needs to be removed to allow the permanent molar to erupt. After the permanent molar then grows in, it will need to be pushed backward to allow space for the permanent second bicuspid to grow in, and then a space maintainer will need to be placed.  An orthodontist should be consulted, because if the permanent molar can be guided to grow in without loss of the baby molar, there will not need to be a space maintainer.