Frequently Asked Questions
why do my lower teeth crowd?
Why your lower teeth tend to crowd is still uncertain but in about 10% of cases the lower erupting wisdom teeth are thought to be responsible, the remaining cases are thought to be due to a process called late stage growth. This occurs particularly between the ages of 21 to 28 and is essentially continued vertical growth of the face.
The important point regarding this late crowding of the lower teeth, is that this will happen whether you have treatment or not. By having orthodontic treatment you begin with a better starting point (i.e. straight teeth)
If you have orthodontic treatment and you also wear your retainers long term you will resist the growth effects on your teeth which cause them to crowd and will thus maintain straight teeth and an attractive smile.
How long is long term retention?
This unfortunately means forever on a nightly or perhaps weekly basis, certainly between the ages of 20 to 30, because your face is continually growing all be it very slowly in a vertical direction.
Will the retainers restrict the growth of my jaw’s?
This is unlikely because the transverse and front back growth of the jaws that supports your teeth has just about ceased by the age of 10.5 and certainly by 12, although the rest of your jaw will continue to grow in length, for as long as you continue to grow.
What will happen if I do not wear my retainers?
In general your teeth will move back to about a third of their original position.
If your teeth originally stuck out, so long as the lower lip covers your upper front teeth when you lips are at rest, they are unlikely to stick out again.
Situations which are particularly prone to relapsing (or returning back to their original position) after treatment, are teeth which were previously rotated or had gaps/spacing between them.
The type of treatment your orthodontist has given you will also influence the stability of the result:
If you expand the jaws in which your teeth sit, beyond the patients own biological limits after treatment the teeth will tend to rapidly return to their original position if no long term retention is advised.
This is a removable brace which postures the jaw forward to correct prominent front teeth.
If you stop wearing the brace too quickly the front teeth can start to stick out again. Ideally once the front teeth have been made less prominent, the patient should wear the brace on a night only basis until they stop growing,
The Effects of Orthodontics on the Profile
Recently in the press there has been a lot of discussion about the effects of orthodontics and particularly extractions on the profile of a patient.
The important issues are that teeth need to moved greater than 5mm forwards or backwards to begin to have any appreciable effect on the position of the lips. This effect will be greater in patients with thin lips.
However one must remember that the relative sizes of the nose and the chin have a far greater bearing on the profile than the lips. But if you have a large nose small chin, thin lips and the lips loose just a few mm of lip support the effect can only be negative, so when planning extractions it is important that the profile is assessed properly.
I have been told I have a poor bite do I need treatment?
The types of poor bite are not clearly classified but essentially if your jaw slides on closure more than 2mm then correction of your bite must be treated with care. Whether a poor bite will effect you jaw joints (or temporamandibular joint TMJ) is another debatable point.
About half the profession believes that if your jaw slides to one side then you will unduly load one of the jaw joints while stretching the other joint, over the years this causes deterioration of the joint eventually resulting in pain.
The problem with this theory is that many people display a slide on closure and never experience pain, while many other people have no slide and still get pain.
The other half of the profession believes that stress plays a greater role in TMJ disorder. Because when people become stressed they can grind there teeth or habitually posture into different positions. These unusual movements overload the jaw joints, leading to pain.
Hence the bite is an important part of the mouth to assess, but a poor bite does not necessarily mean you have to have treatment. In the same way correcting a poor bite will not necessarily cure jaw joint pain.
Are their any risks to treatment
Your brushing should be monitored regularly otherwise there is a risk of tooth discoloration. By this I mean permanent black brown marks left on your front teeth after treatment.
The roots of your front teeth should be professionally assessed to ensure they are up to being moved, small or fine roots have an increased risk of being resorbed during treatment, which could result with you being left with mobile front teeth, however this is rare. If force levels are not properly delivered to the teeth during treatment, high forces can increase the risk of damaging the roots of teeth again compromising the support of your teeth.
Light forces are the ideal, because remember you are dealing with a living system, high forces merely squash and kill the cells which actually move the teeth.
The risk of the treatment relapsing or going back to their original position can occur if the retention regime is not planned properly.
How does a fixed brace work?
There are different types of mechanics but the most common fixed brace the pre-adjusted straight wire brace works by initially lining up the teeth on a very springy flexible wire. Then one slowly increases the thickness of the wire until you can use a very stiff stainless steel wire this acts like a train track along which you slide the teeth around into their correct position.
why do you need to extract teeth?
The two most common reasons for taking out teeth are to make space for aligning crowded front teeth and to make space for reducing the prominence of front teeth which stick out.
Can you avoid extracting teeth?
There several methods:
By proclining the lower front teeth you essentially make the lower arch bigger hence making space for the crowded teeth. In the same way if you parked cars on a crescent, if you parked the same number of cars round a larger crescent you would have spaces between the cars.
This method works well but the problem is the size of your dental arch is really determined by your surrounding lips , if you start invading this space when you take off the brace your teeth will tend to move back into their original position, so ideally you should have a fixed permanent retainer placed, this is a very thin wire placed behind your front teeth so it cannot be seen and will hold the new position of the teeth so they do not crowd back up again.
When considering non-extraction periodontal health has to be professionally assessed because obviously you do not want to expand the teeth beyond the limits of the surrounding bone.
Unfortunately the removal of teeth does not guarantee stability because a process called mesial drift is occurring this is a process where by your back teeth are always moving forwards very slowly and this combined with late stage growth tends to cause particularly the lower front teeth to crowd again after treatment. however it could be argued that at least it eliminates the problems of expansion hence it swings stability slightly more in your favour.
However I not saying that you should extract in every case, I am merely saying that the decision is a balance between the value of a tooth and the reliance on retention. these priorities will be different for each patient.
Making Space using Headgear
Another way of making space is to move the upper teeth backwards. This space could then be used to align the crowded or prominent front teeth. This is achieved using headgear. This is a braced worn after school through the evening and at night for about six months, it works well but must be fitted professionally to prevent the risk of eye damage should the headgear disconnect on the patient.
How does a functional brace work
This is still debatable, but most of the research shows that 90% of the effects are dental, the remaining 10% are skeletal. This means if you have very prominent upper front teeth, the lower teeth move forward, the upper teeth move back (these are the dental movements) and there is possibly a small enhancement of lower jaw growth (1 to 2 mm) and some restraint of the upper jaw growth (1 to 2 mm) (these last two movements are the skeletal movements). The sum of all these effects means the prominence of the teeth is reduced. This treatment is best carried out during the child’s most rapid growth phase and research shows is most stable towards the end of this growth phase, the timing of the child’s growth phase is obviously very difficult to predict.
Many people have tried to predict the pubertal growth spurt but the problem is, because everyone is so different (normal variation) any trends that might be seen are lost in the mass of variation, so beware of anyone who says they can predict how your face will grow because at the moment it is just not possible.
All we can predict is average growth i.e. if a child has a small lower jaw at 8 years of age, by the time he is 13 it will probably be bigger, however how much bigger and when it will get bigger and in which direction (in terms of direction there are some fairly good anatomical radiographic indicators which do give you some good hints) it is just not possible to predict.
Probably the most useful indicators or hints, are what the parents and their relatives look like. Also because we are unable to predict how much some one’s jaw is going to grow, the timing of treatment becomes an issue.
Specialists who practice early treatment argue that by treating someone from the age of 8 through to 14 years of age, growth can be enhanced and the direction of growth controlled to give a favourable result. The arguments against this approach are that:
Who is to say that they may have grown that way despite treatment
How long will the skeletal effects by the brace last ?
There is evidence to show that although in the short term skeletal effects can be seen after the brace has been stopped slowly the true genetic pattern takes over, hence if you have a small jaw genetically you will have a small jaw no matter how much treatment you have.
The other issue is; should we be subjecting a child to wearing a brace for most of its young life when the outcome is not guaranteed and we can only achieve small long term changes. Maybe it is better to delay treatment until they are 12 and assess the degree of growth change, if the jaw still very small maybe surgery would achieve a more desirable change and have a better long term outcome and in the same way if growth has been favourable, early treatment would have been unnecessary anyway.
I am not saying that early treatment is always unnecessary because sometimes even a few mm of extra growth can make a big difference to the appearance of the patient after treatment. This situation would need to be discussed with a professional who would carry out a full assessment of the problem with a clear long term plan, bearing in mind the wishes and concerns of the child and the parents.
Are there alternatives do prominent teeth have to be treated?
Prominent teeth tend to be treated because they are at risk from trauma (if your teeth stick out ore than 7mm you have a 50% change of knocking them in some way which may require them to be repaired. The other reason is that prominent teeth tend to look unsightly and distract from the patients smile; but not always, a recent study on top models showed there teeth stuck out, an average of 8mm normal is 2 to 4 mm (the normal front tooth prominence is based on a sample of school children who were not necessarily all attractive) so treatment of prominent teeth is a very personal choice based on the way you perceive your smile and the age you are (young kids have a greater chance of knocking their teeth as they tend to be more active).
My teeth are ok now but will they get worse?
Some people worry, that although their teeth look good now, the position of their teeth may get worse as they get older.
The answer to this can only be based on long term clinical studies and these show that in general your upper teeth remain fairly stable and remain in there original position, but your lower teeth do crowd slowly as you get older, particularly in women.
Why would I need orthodontics?
The reason for having orthodontics is divided into two main sections:
Aesthetics i.e. the way your smile looks, this is a very personal issue and your view is very important here, if you are happy with the way your teeth look then there is no need for treatment. Even if you are outside normal measurements; for example the normal range for teeth that stick out is 2-4mm, however this based on a sample of school children who were not all necessarily attractive!!.
A recent study of top super models found that the average prominence of front teeth was 8mm, so you can see the danger of saying that someone needs treatment just because their teeth are more prominent than 4mm.
Function is important because teeth which meet incorrectly will not pass occlusal or eating forcers correctly through their structure, hence if a tooth with a filling is overloaded then the tooth or filling could fracture, further compromising the life of the tooth.