Our teeth stay anchored to our jawbone, thanks to healthy tissue and
ligaments. Normally, the roots and ligaments for primary ("baby")
teeth will dissolve, allowing the baby teeth to come out and the permanent
teeth to emerge from underneath.
Sometimes the roots don't dissolve properly, and instead they fuse directly
to the jawbone. The fusion may occur because the ligament that normally
surrounds the tooth in the jawbone is lost. This condition is called ankylosis
Causes of ankylosis
The causes for ankylosis vary; for example, the healthy ligament cells may
dry up and die because of:
- Inflammation or infection
- Problems with metabolism or
normal bone growth
- Congenital tendencies
- Gaps in the membranes around
- Abnormal pressure from the
- Crushing or other damage
Ankylosis also may develop in children or adults when an injury (such as
with sports or accidents) causes the top of the tooth to be broken off, leaving
the roots behind.
Some studies have indicated that 1 to 3 percent of children may have
ankylosis with one or more primary teeth, while other studies have indicated
more than 38 percent of children may have ankylosis. Studies also have shown
that children or adolescents with 1 or 2 ankylosed teeth are more likely to
have additional ankylosis later.
These variances in statistics may be due to different ways of diagnosing
ankylosis, ethnic factors, or other reasons. (For example, a study at the
Pediatric Dentistry Clinic of the University of Minnesota's School of Dentistry
focused only on Caucasian children.) But the studies all come to the same
conclusion: while it may not be an unusual condition, especially with lower
first molars, ankylosis is a serious condition. To ensure the healthy development
of your child's teeth, ankylosis must be addressed.
Signs and sounds of ankylosis
Some of the signs of ankylosis may
- The ankylosed tooth appears
submerged because its roots don't grow at same rate as other teeth.
- The opposing tooth visibly
loses alignment as it grows out of its socket.
- The permanent tooth is
blocked out of position because the primary tooth's roots failed to
Often we can diagnose ankylosis simply through observation. For example, a
tooth noticeably lower in growth is a tell-tale sign of ankylosis. Also, with
x-rays taken at regular checkups, we can view the development of permanent
teeth that may be blocked by the primary teeth's roots.
Special, sophisticated instruments can be used to identify ankylosis. But
one of the most reliable instruments is our ears! Simply by tapping on the
teeth, we can hear a distinct difference between an ankylosed tooth and a
normally growing tooth. That's why we may use the clean handle of a dental
mirror to tap lightly on children's teeth as part of their regular dental exam.
(An ankylosed tooth has a higher pitched or dulled sound as opposed to the more
cushioned sound of a normal tooth.)
Solutions for ankylosis
We may recommend several solutions for ankylosis, depending on the specific
tooth and your child's situation. For example, with younger children, we
may simply recommend monitoring the situation for a period of time, to
watch how the primary and permanent teeth develop.
Sooner or later we may recommend removing the ankylosed tooth, to ensure
that your child's permanent teeth can develop straight and strong. We also may
recommend surgery to expose, protect, or reposition the emerging tooth.
If we must remove a primary tooth before the permanent tooth is ready to
emerge, we may use space maintainers to ensure that surrounding teeth do not
crowd out the emerging permanent tooth. Sometimes orthodontic steps may be
taken to ensure that your child's teeth align and the bite is correct. In
general, the sooner we can deal with your child's ankylosed tooth, the fewer
problems that are likely to develop later.
For more information
If you have questions or concerns about ankylosis affecting your child's or
adolescent's teeth, please call our office. Also, you might find the following
- "Ankylosis of
Traumatized Permanent Incisors: Pathogenesis and Current Approaches to
Diagnosis and Management" in the Journal of the Canadian Dental
Association, November 2005 at http://www.cda-adc.ca/jcda/vol-71/issue-10/763.html
- "Ankylosed primary
molars: Results and treatment recommendations from an eight-year
longitudinal study" (messer-02-01.pdf), "Diagnosis and treatment
planning for unerupted premolars" (burch-16-02.pdf), and "Early
ankylosis of a primary molar with self-correction: case report"
(belanger-08-01.pdf) in Pediatric Dentistry; PDFs available at the American Academy of Pediatric Dentistry at http://www.aapd.org