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home : orthodontics : relapse

There is only one way to completely avoid relapse. At the end of treatment, remove the braces, polish the teeth, make study models and take photographs. And then take the patient out the back door of the office and shoot him
- Dr Tom Graber DMD
South African Dental Congress. August 1992

Relapse is a dirty word in orthodontics. It means that, after all that orthodontic work with all that expense and with having to put up with wearing appliances or braces for all those important years [including the School Ball - horrors!], it all turns to custard!

There are many orthodontic cases that remain permanently stable, preserving that beautiful appearance and the ideal occlusion without the slightest sign of any drift away from glorious perfection. There are cases that defy the stresses of the mouth - the incessant gum chewing, the tongue thrusting swallow, the constant clenching and grinding of teeth - to maintain the beauty of the newly completed smile.

But many - in fact, most - do not. Over months or years, spaces reopen, teeth twist or bend, crossbites reoccur, and teeth once again are pushed out of their militarily aligned rows of sparkling ivories.

There are no ways we can predict in advance whether the teeth are going to sit meekly in position at the end of treatment or whether they are going to motor off all over the mouth. No blood tests or xrays or measurements will set off warning lights. We do get a bit of a clue, however, if the whole family arrives, each with a mouth resembling a front-end loader. However there are so many variables in crooked teeth - like a deviate swallow or environmental allergies - that we just treat the muscle problems we see - like the thumb sucking or tongue thrusting - correct the crooked teeth and jaws, and hold the teeth in position until they settle down and behave themselves. Or that's what we intend - while the Relapse bogey hovers behind a Carabelli's Cusp, waiting to pounce!

Orthodontic specialists know this. And general dentists certainly know this. Because they are the ones who see the patients year after year and can chronicle the teeth as they slip into their old patterns.

An excellent article reviewing the orthodontic literature on retention and stability was published in the September 1998 American Journal of Orthodontics and Dentofacial Orthopedics. The authors were Marielle Blake, an Orthodontist staff member of the Dublin Dental Hospital in Ireland, and Kathryn Bibby, an Orthodontist in British Columbia in Canada [and the daughter of respected Auckland dentist Alistair Bibby]. They discuss the various factors associated with post treatment stability - changes in the shape of the jaws, teeth being pulled out of line by stretched gum fibres, the returning of teeth to their old positions [teeth have memories!] as especially seen in the lower incisor area, muscle forces, continuing growth of the head and jaws, and the effect of the erupting wisdom teeth on tooth position [a contoversial topic]

The article then goes on to discuss relapse related to different orthodontic techniques. These were detailed as:
Late extraction followed by full treatment: this is the type of treatment carried out by most orthodontic specialists in this country. Premolar [or side] teeth are removed for overcrowding and fixed braces are placed on the teeth for two years or so. The article stated that the overall success rate 10 years after treatment was completed was less than 30% with 20% showing marked crowding. This 30% success rate reduced to 10% at 20 years after braces were removed
Serial extraction: in this technique, permanent teeth are extracted but no appliances are used. Crowding returned, but it was not as severe as before treatment started.
Serial extraction followed by appliance therapy: permanent premolar teeth are extracted when [or before] they erupt and then appliances [braces] are used for several years. Unsatisfactory lower incisor alignment occured in 73% of the cases and a decrease in jaw size was found in 29 of 30 cases.
Non extraction therapy with expansion: the jaw size is developed with either braces or palatal expansion appliances and no teeth are extracted. This technique is used by both specialist orthodontists and general dentists in New Zealand. The overall success rate in one study was only 11%. Another researcher looked at results where palatal expansion was used along with braces. He found good stability for all areas of the mouth apart from the lower anterior teeth. It was considered that prolonged retention following treatment helped maintain an acceptable result.
Early mixed dentition therapy without braces: Orthodontists tend to delay treatment until all the permanent teeth have erupted. We, on the other hand, prefer to treat children when they still have most of their baby teeth present - so we do lots of this type of treatment. The article stated that there was satisfactory alignment of the lower incisor teeth in 76% of the patients. This researcher noted that early establishment of the arch width and corrected occlusion in the mixed dentition provided better long term stability.
Non extraction therapy where there is general spacing of the teeth: This was the most stable treatment type with an overall success rate of 50%. But some spaces tend to re appear - the diastema [space] between the upper front teeth being the worst offender
Lower incisor extractions: we hardly ever extract permanent teeth - maybe one patient in 100. But, where there is extreme crowding in the lower teeth - and especially in the older [15 years or more] patient, then we may suggest removal of one lower incisor tooth. We consider this far preferable to the 2 or 4 tooth premolar extractions carried out by many of our colleagues. In a study, 71% of patients who had one incisor removed showed acceptable results.

In summary, this Review Article stated that only three modalities showed acceptable long term alignment of the lower front teeth [the bench mark for success]. They were:

The early mixed dentition treatment with no braces - we do this lots
non extraction treatment with spaces - we do this too
lower incisor extraction cases - we do this where necessary

So there you have it. Many of the researchers consider that life long retention - like wearing wires behind the lower front teeth forever - is the only way to preserve the position of corrected teeth. There is no gold standard in retention. Some dentists cut around the gum margins to reduce the pull of the gum fibres on the teeth. Others routinely remove wisdom teeth. As I have said, many researchers don't believe this makes a significant difference to post treatment recrowding.

This photo has absolutely nothing to do with relapse, but I thought you could be dropping off to sleep at this point, so this should wake you up for the next bit which I consider to be rather important!

What makes me cranky is that there are some Specialist Orthodontists around [certainly not all of them, but just enough to make a nuisance of themselves - I just wish all Specialists were as ethical and as competent as James Pretorius and John Muir] who tell people not to come to us because our treatments "don't work". And then they go ahead and take teeth out [to extract perfectly good teeth means failure if you ask me!] and carry out the technique that Blake and Bibby report has a 70% failure rate after 10 years rising to a 90% failure rate after 20 years! So to avoid that somewhat embarrassing situation they tell their patients they need lifetime retention - what sort of a successful and stable result is that??? If you went to an Oral Surgeon and he told you he had a 70% chance of messing up the removal of your wisdom teeth, I reckon you would be out of that chair and out the door in a flash!

Now here is an interesting thing! If you go to the official web site of the NZ Association of Orthodontists, you won't find anything on relapse - I don't think you will even find the word there! It's almost like if you ignore it, it might go away. But, as I have explained above, that doesn't happen and the techniques the specialists commonly use are more likely to relapse than are the techniques we commonly use. The site starts off with a sensible section on describing malocclusions, but then it stuffs up by answering the question "When to start and how long is treatment?" with "...patients are rewarded with healthy teeth, proper jaw alignment, and a beautiful smile that lasts a lifetime". Hold on a minute here, mate! If the writers were being honest [and ethical!] they would have written "...patients are rewarded with healthy teeth - apart from those teeth we have had extracted, proper jaw alignment - apart from flattened profiles where teeth have been extracted or those cats whiskers head straps have compressed the jaws, and a beautiful smile that lasts a lifetime - provided they wear permanent retainers, to hold the teeth in position, for the rest of their lives" This looks like a case of deceptive advertising for sure!

However these specialists have found room on their site to write some rather scathing stuff on 'functional appliances' - funny that! Trouble is that almost all they have said could be classified as 'disinformation' or even straight out lies! For example, the site says "these claims [that functional appliances work] have no scientific evidence to support them". Yeah right! Every orthodontist in this country knows that there is plenty of evidence in the refereed dental literature supporting the effectiveness of functional appliances.

Now the web site of the American Association of Orthodontists is rather different. They have a very interesting article on something that is sometimes mistaken as relapse of the lower incisor teeth following orthodontic treatment. It is called late mandibular incisor crowding (note:pdf file). I will say no more - read the article. It makes sense

Now I can already see the orthodontists in the back row jumping up and down and shouting "See we told you, we don't get relapse, its all Late Mandibular Incisor Relapse!" Now there is of course going to be some overlap between post orthodontic relapse and this late mandibular incisor relapse stuff, and studies that concentrate on movement of the lower incisor teeth could be suspect because of this blurring of causes. But lets not be diverted here. Relapse and tooth movement happen - and not just to cases treated by general dentists, but to many cases treated by every dental practitioner - orthodontist and general dentist - who is brave enough to shift a tooth! And as well to most people who have never had a smidgem of orthodontic treatment of any sort ever.

Actually people are now beginning to understand that teeth do tend to move throughout life. We have many adults who had orthodontic treatment when they were teenagers returning for another treatment in their 30s or 40s. And we do have short and relatively simple treatments for adults who want a booster-dose of orthodontics to help them through their mid-life crises

Consider this. If your child has had 4 premolar teeth removed at the start of treatment because of crowding, and then 4 wisdom teeth removed at the conclusion of treatment, then he/she has lost one quarter of his/her dentition - and isnt even an adult yet! Is that going to make a difference to the nice round full smile you are expecting? You bet. Is it going to likely cause a sinking in of the lower face in profile with a longer looking nose and chin? You bet. And is it going to lead to a smaller overall mouth where, because of the reduced space, the tongue gets stuffed back into the throat and later in life there will be a much increased chance of snoring and sleep apnoea and other airway disturbances? You bet!

We believe that by treating patients really early - most of our patients start treatment at 8 or 9 years of age - and by getting the jaw shape and relationship corrected before the permanent teeth erupt - then we are minimising the chance of relapse. And if we weren't getting a high percentage of good results, then I quite simply wouldn't be doing this stuff! And we certainly won't be telling you to wear retainers for the rest of your life!