Why did my teeth shift after the braces came off: part 4- The Finish

Reasons for Relapse Part 4: Reasons for relapse: Finishing a case properly to minimize relapse

 

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 #4. How ideally the case was finished.

 

In an ideal world, teeth have certain angulations (tips) in order to function properly.  Upper front teeth and lower front teeth should tip slightly forward toward the lips.  Upper back teeth should be vertical, or have very slight tip toward the cheeks.  Lower back teeth should be vertical or have very slight tip towards the tongue. All of these angulations are dependent on the position of the underlying bone.

 

In a front to back direction, the top jaw should be very slightly in front of the lower jaw (Class I skeletal relationship) in order to achieve the proper anterior tooth tips.  If, however, the jaws are not aligned ideally the angulation of the front teeth can be adjusted to achieve the scissor like relationship of the top to bottom front teeth. These adjustments are called dental compensations.  Now suppose the upper jaw is too far forward for the lower jaw (Class II).  If the teeth are angled properly to their supporting bone, the top front teeth will stick out too far for the lower front teeth.  The angulation of the teeth can be changed so that the roots can remain in the bone, but the crowns (the visible part of the teeth) can still meet like a scissor in the front.  The top front teeth can be tipped more toward the tongue, and the lower front teeth can be tipped more toward the lip. These dental compensations often occur naturally, but can also be applied by the treating orthodontist in order to achieve proper function. Now suppose the lower jaw is too far forward for the upper jaw (Class III). If the teeth are angled properly to their supporting bone, the top front teeth will be behind the lower front teeth.   In order to get the top teeth in front of the lower teeth, the top teeth can be tipped more toward the lip, and the lower front teeth can be angled more toward the tongue. Although small amounts of dental compensation are very acceptable, large amounts of dental compensation create an unstable bite. The teeth may try to find more favorable inclinations, and teeth that were tipped towards the lip (creating a larger arch form) will move towards the tongue (creating a smaller arch form) and become crowded.

 

Now let’s discuss the side-to-side direction.  If the upper jaw is too narrow for the lower jaw, in order to get the top teeth outside the bottom teeth (if the skeletal base is not corrected) the upper back teeth have to be tipped towards the cheeks, and the lower back teeth have to be tipped towards the tongue. If the teeth are tipped excessively, the teeth will try to find a more ideal inclination, bringing back the posterior crossbite (the top teeth bite inside the bottom teeth.)

 

Some orthodontists, like Dr. Okun, like to treat orthodontic cases early (age 7 to age 10) in order to influence the jaw bone size and position, so that the inclinations of the teeth can be more favorable.  Changing the bone structure might mean moving the bones of the palate apart (palatal expansion), restraining the growth of the upper jaw (traditional headgear), or advancing the growth of the upper jaw (palatal expansion combined with a protraction headgear.) Once the supporting structures are idealized, the permanent teeth can erupt into straight positions. With Dr. Okun’s technique, it is rare for early treatment cases to need a second phase of treatment.

Some orthodontists like to treat orthodontic cases later (age 11 to 18) in order to have all of the permanent teeth present when the case is finished. The advantage of teen treatment is that you are likely to need only one phase of orthodontic treatment.  The disadvantage is that you need to tip teeth less ideally in order to compensate for growth that has already taken place. You also are more likely to need extraction of permanent teeth in order to align the remainder of the teeth in a crowded case. Relapse potential is much higher in cases that are treated later, i.e. the teeth don’t stay in place after the braces are removed.  The later the case is treated, the more likely it is that the patient will need retainers at night forever in order to maintain their result.