Friday, October 26, 2012

Failure of Permanent Teeth to Grow Into the Mouth Part I

There are two reasons why permanent teeth do not grow in.  Either they are impacted (meaning they cannot grow in because there is insufficient room, or they are growing in a wrong direction), or they are missing.

The presence of only three lower permanent incisors, and no visable lump in the fourth one, might cause you to suspect that one is missing.  X-rays and careful counting will answer this.  An Orthodontist should be consulted immediately because either the impacted tooth will need to be brought in with braces or else the effect of the missing tooth will need to be planned for in the bite.

Similarly, the presence of only two permanent lower incisors while two permanent cuspids are already erupted probably implies the absence of the other two incisors (since there are normally four incisors).  A decision must be made early by an Orthodontist whether to open the space for later replacement of the missing teeth with implants, or to close the space if that would be better.  Space closure might involve substituting the cuspids as lateral incisors, and substituting the first bicuspids as cuspids by partially reshaping them.

If this decision is delayed, or improperly made, excessive protrusion of the upper incisors or excessive vertical overlap of the upper incisors over the lower incisors may result, leading to long orthodontic treatment, and contributing to an unpleasing lip profile.