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.

Halloween- reposted from October 31, 2010, and still relevant!

 

Halloween is nearing the end, and all our children will be enjoying their candy tonight. Here are some hints to preserve their teeth:

- Sticky candy will break braces and aggravate TMJ problems. If you are wearing braces or have TMJ/facial pain DO NOT EAT chewing gum, gummy bears, taffy, jelly beans, and other sticky candies. If the candy is hard to bite through, break it into very small pieces before eating it.

- Avoid eating candy that sits on your teeth a long time. A Kit Kat Bar or a Hershey's Kiss will do less damage than a lolly pop or sucking candy.

- Rinsing your mouth with water after eating candy will decrease the risk of white spots and cavities. In addition, spraying your mouth with Carifree spray or sucking a xylitol "candy" will inhibit the bad bacteria (in  your mouth) that have feasted on the sugar you just ate.

- Rinsing with fluoride rinse before bed daily (especially important if candy was eaten that day) will help reverse the damage that candy does to your teeth.

- If there are already white spots (the beginnings of cavities) present, your dentist can use Curodont to help the lesions remineralize (fading the white spots.)

Why did my teeth shift after the braces came off? Part 3: unfavorable growth.

 

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 #3: unfavorable growth.

Unfavorable growth is the growth that takes place after the braces are removed which destroys the final bite. One jaw grows more than the other. The teeth in each jaw may stay perfectly aligned, but the bones that support the teeth may not stay in balance with each other. 

We can all see that children look like their parents.  Facial balance is also genetically determined. Parents with “buck teeth” have children with “buck teeth”; Parents with “underbites” have children with “underbites.” Although we can change the skeletal balance and esthetics with orthodontic orthopedics in young patients, the patients continue to grow after their active orthodontic treatment is complete.    A patient who started with their front teeth sticking out “way too far” will relapse in that direction- their top jaw will continue growing and after several years they may have front teeth that stick out farther than when they completed treatment. This relapse growth issue is seen most vividly in “underbite” cases. The bottom jaw will continue growing for many years after the top jaw stops growing, so a patient who started with a prominent lower jaw will continue growing that prominent lower jaw and the lower jaw may “outgrow” the balance that had been achieved with the orthodontic orthopedic treatment. In addition, lower jaw bones rotate internally, although the outside remodels and looks the same.  The lower front teeth  tip forward with this rotation and in order to stay behind the upper teeth, the lower teeth develop "middle age crowding."

The skull, like the rest of the body, shows early growth “high up” and later growth “low down.”  We see this in babies who have large skulls with respect to the rest of the body versus adults who have small skulls with respect to the rest of the body.  The skull stops growing earlier than the legs stop growing.  Within the skull, the top of the face stops growing earlier than the bottom of the face. The midface stops growing earlier than the lower face.  With orthodontic orthopedics (palatal expansion with headgear treatment) we can modify the growth of the maxilla (upper jaw), which is in the mid-face. Palatal expansion is successful in girls until about age 12, and in boys until about age 14, when the midface stops growing.  While creating width of the upper jaw (palatal expansion) forces can be exerted on the jaw to restrain the growth (traditional straight pull headgear to the top of the head and the back of the neck) or to increase the amount of growth in the forward direction (with front pull headgear against the forehead and chin.) These treatments are no longer effective after the midface has finished growing because the sutures (the zippers between the bones) close with physical maturity. The mandible (the lower jaw which is in the lower third of the face) continues to grow for many more years than the maxilla (upper jaw bone), until about age 17 in girls, and until about age 23 in boys.  If the mandible was genetically programmed to be small, we do not notice the forward growth of the mandible after the maxilla stops growing.  If the mandible was genetically programmed to be large, the forward growth of the mandible is obvious and often results in a return of the “underbite.” 

When I treat “underbite” cases I overcorrect the forward correction of the maxilla, leaving the young patients with the opposite problem from which they presented.  They start with the upper teeth and jaw behind the lower teeth and jaw, and I finish them with the upper teeth and jaw too far forward for the lower teeth and jaw. An ideal bite has the upper front teeth one to two millimeters in front of the lower front teeth.  A Class III underbite may have the upper front teeth behind or tip to tip to the lower front teeth.  I overcorrect the jaw position leaving the upper teeth three to four millimeters in front of the lower teeth in order to allow for up to 2mm more lower jaw growth in the future.  I do not aim for a correction of over-jet to 5mm because I do not want to take the risk that the lower jaw does not have a late growth spurt, and the final result (as an adult) remains with excessive over-jet (seen as “buck teeth.”) Anticipating how much relapse growth will take place is an educated guess based on family history and the appearance of the parents.

Another phenomenon, related to unfavorable growth is the relapse of tooth rotations and teeth that grew in to the outside or inside of the arch form.  The longer the teeth “live” in the poor position, the more they have ingrained that “memory” of that position.  If the size of the arch form is corrected early and the teeth grow into a straight position, the teeth are more likely to stay in a straight position.  If the jaw size is corrected and the teeth aligned within a year after the teeth erupt, the teeth are more likely to stay in a straight position.  If the jaw size is corrected as an early teenager, the teeth already have a memory of the crooked position, and are more likely to return to that crooked position after orthodontic treatment has been completed.  If the teeth are aligned in adults, after facial growth is complete, the teeth are much more likely to return to the crooked position.  This is why night time retainer wear is so important in patients whose teeth were aligned later in life.

Why did my teeth shift after the braces came off? Part 2: mouth habits

 

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. 

Why did my teeth shift after the braces came off? Part 1: retainers

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 #1: the patient did not wear his retainers properly.

In order for teeth to move with orthodontic treatment, the bone around the teeth has to remodel.  The bone on the pressure side (the side to which we are moving the teeth) resorbs, and bone on the tension side (the side from which we are moving the teeth) rebuilds.  Over time, the teeth are surrounded by new bone.  This new bone is immature and weaker than mature bone. 

Imagine that you broke a bone and went to the orthopedist to reset the bone.  After aligning the bones to the best position, the orthopedist would put on a cast to hold the bones still, in that new position, until the bone fills into the break, and matures in that position.  The retainer is like the cast.  The teeth are slightly mobile when the orthodontic treatment is completed and the teeth need to be held in their final positions while the bone holding them matures.

A good retainer is rigid, like the cast for a broken bone is rigid.  It should hold the teeth still even if the patient leans his tongue on the retainer, or if the patient clenches or grinds his teeth.  Rigid retainers are made of hard acrylic, and have wires that hold them and the teeth in place.  

It has become common for orthodontists to use other forms of retention. Essex and aligner retainers are non- rigid vacuum formed retainers which are less expensive to make, and are less effective because they flex when forces are applied to them.  These plastic retainers also stretch out over time and need to be replaced frequently. If the treating orthodontist does not intend to provide long term retention care he may choose to use this style retainer.

It is also common for the orthodontist to "glue" the front teeth together, often with a wire or fiberglass thread that is bonded to the tongue surface of the teeth.  Bonded retainers will hold the front teeth straight with respect to each other, but the bonded  can move as a unit with respect to the back teeth.  The bonded retainers offer no retention to the back teeth, and if the patient has mouth habits (like grinding the teeth) the retainer will break as the back teeth move vertically. Bonded retainers are difficult to keep clean, and often have issues with developing cavities and gum disease.

A removable retainer has to be worn "fully seated."  If the patient lifts the retainers with his tongue, or floats it above his teeth, it cannot do it's job.  If the patient repeatedly moves it in and out with his tongue he may actually make the teeth looser, rather than letting the teeth "tighten up." If the retainer is "floating" it is not contacting the teeth, and therefore cannot hold them in place. If the patient is holding the retainer in his hand, instead of wearing it in his mouth, the retainer can also not do it's job.

Retainers should be worn full time until the teeth "tighten up".  This takes between two and six months.  Then the wear-time should be decreased, and the mobility of the teeth should be evaluated by the orthodontist.  If the retainer always feels the same when it is replaced after a period of time, as when it is replaced immediately after removing it, it means that the teeth have not moved when the retainer was out of the mouth.  If the retainer feels different after it has been left out for a period of time, it means that the teeth had a chance to move somewhere, and the retainer had to push the teeth straight again.  The goal is to eliminate the habits that are causing the teeth to move, in order that the teeth stay in place when the retainer is removed.  Over the course of the first year the patient should be able to decrease wear-time to be only when sleeping.  The orthodontist needs to evaluate whether it is necessary to continue retainers at night indefinitely, or whether the patient can discontinue night time wear of the retainers when his face finishes growing.