Why did my teeth shift after the braces came off?
I often hear from patients that their teeth moved after
their braces came off and they want to know why. There are basically 3
reasons for a failed case (that was treated well.)
1. The patient did not wear their retainers properly. This
is patient error.
2. The patient did not eliminate mouth habits, and did not
wear appliances to protect them from their mouth habits. This is a combination
of patient and dentist error (if the dentist did not make the patient aware of
their habits, and/or did not make appliances that could protect the patient
from these habits.)
3. The patient grew unfavorably. No one had control over
this one.
4. If the teeth were not aligned in the middle of the bone
ridge, they will relapse to be centered in the ridge again. The treating
dentist had control over this reason.
The next few blogs will address these errors. Today we will
address #2: mouth habits.
A mouth habit is something you do with your mouth other than
talking and eating. Some examples
include biting your fingernails, biting your pen/pencil, chewing on your lips
or inside of your cheeks, leaning your tongue on your teeth, and
grinding/clenching your teeth. Any force that you exert on your teeth, if it is
applied for enough time, will move your teeth.
Patients who bite their pencil consistently in the same area of their mouth
will either push the bottom tooth toward the tongue, push the top tooth out towards
the lip, or a will form a gap vertically between the top and bottom tooth where
the pencil sits. Patients who chew on their bottom lip create crowding of the
lower front teeth, or spacing between the upper front teeth.
Tongue habits can occur in different areas of the mouth. If
the tongue sits over the tops of the side teeth it can create an open bite
which is an area where the top teeth do not touch the bottom teeth when the
patient is biting their teeth together. If the tongue is leaning against the
front teeth down low, it will create spacing between the lower front teeth,
just as if it is leaning against the front teeth up high, it will create
spacing between the upper front teeth.
If it is leaning between the top and bottom teeth in the front it will
create an anterior open bite, i.e. the top teeth will not overlap the bottom
teeth in the front. Sometimes the patient leans their tongue on specific teeth with
less force or duration, and instead of moving the teeth, the excessive force
generated on the teeth accelerates loss of bone and gum around the teeth.
(Periodontal disease is an inflammatory disease of the supporting structures of
the teeth- the gums and bones. It is cause by bacteria which live in the
mouth. When the bacteria are removed
frequently (by daily brushing and flossing) the inflammation levels are low,
and there is no disease. When the
bacteria are not efficiently removed, the “bad” bacteria set up housekeeping
and flourish causing inflammation which is seen as red, puffy, bleeding
gums. Over time the bone around the teeth
is lost leaving the roots of the teeth visible in the mouth. When there is excessive force applied to the
teeth, from leaning the tongue on the teeth or from clenching/grinding the
teeth, the rate of bone loss is accelerated. Then the roots start showing even in
cases where the gums are not visibly red, puffy, and bleeding.)
Bruxism is the clenching and grinding of the teeth. Clenching is when the teeth are tightly
closed when there is no reason, like chewing, to be closed. Grinding is when the patient moves the teeth “side
to side” or “front to back” as if they are chewing, but there is no food
present to chew. The most common reason for bruxism is stress, but it also
occurs from boredom, concentration on a difficult task, or when a young child
has pressure in their ears which they are trying to relieve. Bruxism does a lot
of damage to the teeth and their supporting structures (which was discussed in the post October 21, 2020.) Bruxism can also move
the teeth. When clenching, the back
teeth which meet vertically, are pushed deeper into the bone, much like a nail
can be hammered into a piece of wood. As
the posterior bite support is lost, the front teeth start to overlap more vertically
(i.e. the bite deepens), and the front teeth bypass each other (like a
scissor.) In order for the lower teeth
to stay behind the wedge shaped upper front teeth, the lower front teeth start
to crowd, and the upper front teeth start to develop spaces between them.
Habits can be controlled in the daytime through awareness,
but it is impossible to control habits like improper tongue posture and bruxism
while one is sleeping.
Retainers and occlusal guards are used in order to prevent
the shifting of teeth from mouth habits. Although retainers should be worn full
time immediately after braces are removed, they can be continued at night
indefinitely to protect teeth from habits.
Mouth habit appliances should be rigid so that they can’t be deformed by
the habit-forces. The design of retainers was discussed in the August 2025
blog. Other appliance designs will be discussed in future blogs.
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