MAXILLARY EXPANSION - UNEXPECTED BENEFITS?

Maxillary expansion is a relatively common procedure in orthodontic treatment for bite correction and I have Blogged previously about it for the correction of crossbite as well as its use in creating space. However, expansion has also been showing some unexpected benefits for some patients in other areas which I will discuss in this Blog.

Expansion of the upper jaw is most effective in pre-pubertal children when the midline suture is still responsive and the surrounding bones are more malleable. As the maxilla (upper jaw) forms the floor of the nasal airway and supports the soft tissues of the nose, this expansion has been suggested to improve a constricted or congested airway. Much of this was anecdotal as improvements can occur coincidentally or with time and not necessarily be related to the procedure. This is why research in the form of clinical trials is important to try to reduce the biases inherent in simply observing something. However there is a growing body of evidence of the potential beneficial effects of maxillary expansion beyond the correction of dental crossbites.

Expansion and Nocturnal Enuresis/Bed-wetting:
In the 1990's some research suggested that expansion of the upper jaw may help reduce nocturnal enuresis or bed-wetting in children. More recent studies agreed with these findings showing significant reductions (~75%) in the number of nights of bed-wetting following expansion with ~30% were completely dry at night after expansion. This was even in the absence of a pre-existing crossbite. Suggested reasons for this improvement relate to an indirect effect on the pituitary gland or an improvement in the airway with expansion which may help with a possible association between enuresis and sleep disordered breathing in children.

Expansion, Congestion, Sleep Apnoea:
One of the above papers also found that nasal airflow increased while nasal resistance to airflow decreased. Earlier research by Peter Vig in the 1980's found that rapid maxillary expansion resulted in a significant reduction in nasal resistance but there was considerable variation and so the outcome was not predictable. Other research has shown this reduction remained a year later. Another paper found those with the highest initial nasal resistance tended to obtain the greatest benefit from expansion with the greatest reduction in nasal resistance.

Maxillary expansion has also been suggested to improve obstructive sleep apnoea or apnea in children (where the child stops breathing several times per hour of sleep). I have discussed extractions and sleep apnoea previously. Studies have found expansion can result in a significant reduction in the numbers of episodes of apnea in children including those with enlarged tonsils and adenoids. Although the response is unpredictable the results are promising enough to warrant more comprehensive clinical trials and to be considered as a treatment strategy especially when there are other reasons to consider maxillary expansion.

Expansion and the Middle Ear:
In studies on patients with narrow arches and conductive hearing loss it has been found that rapid and semi-rapid expansion of the maxilla resulted in an improvement in hearing and eustachian tube function and these improvements held up for 3/4 of the subjects up to 2 years later. However these are children with narrow jaws so the same may or may not hold for those with normal or wide arches.


Summary
So it seems that maxillary expansion may have benefits beyond correcting crossbites and creating some space. However it must be kept in mind these studies are not definitive and the outcomes are not guaranteed so more research in the form of randomised clinical trials is indicated. For this reason expansion may be suggested when it is indicated for other reasons or in consultation between your medical practitioner/sleep physician/Otolaryngologist (ENT) and your orthodontist.


I would like to thank Dr James Noble (Orthodontist - Toronto) for his feedback on this Blog topic.

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia and teaches orthodontics part-time at the University of Queensland and is a visiting lecturer at Seton Hill University in the USA. Peter is one of the editors and authors of the orthodontic textbook, 'Evidence-Based Clinical Orthodontics'.

VIBRATION & ACCELERATED ORTHODONTICS - CLAIMS VERSUS EVIDENCE

Claims of faster treatment with 'special' quick or fast braces or appliances such as AcceleDent, OrthoPulse and others are appearing more and more in the market place and on Google. The companies hope their product can shorten treatment and heavily advertise so - but what is the evidence?

When you are paying up to $1000 or even more for something you want to be sure or pretty sure it works... or not care about the $1000! Some clinicians and patients use the special brace or appliance and feel their treatment went faster and extol the virtues of the appliance while others do not see a difference, shrug their shoulders and move on. When we are told something is better/faster we look for that difference - some remember the ones that worked (the Believers) while others remember the ones that didn't (the Naysayers) and so we now have two camps, both with a biased perspective! This happened with self-ligating brackets where initially it was felt by some that they shortened treatment (and appeared in the media saying so) but later research revealed that in fact they were not (see my previous Blog on Braces claiming to be Fast)!

Currently some state that you can use #Invisalign clear aligners every week instead of every two weeks (as the manufacturers currently recommend) when using #vibration or other appliances. However many patients get away with weekly wear without these appliances anyway while others won't. There are current studies that suggest vibration accelerates tooth movement with braces while a better designed prospective trial finds no difference. I am currently running a randomized clinical trial on the vibration appliance, AcceleDent and the results of this will be available for publication later this year (2015) to further examine any effect of vibration during initial alignment and space closure so this will be discussed in a future Blog. Although the idea of vibration holds some merit, the evidence supporting it is currently of a lower quality while the higher level evidence from a prospective randomized trial finds no difference. More research is obviously required to clarify the debate and will be forthcoming over the next couple of years but it is the quality of the evidence that is important to answering this question.

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia and teaches orthodontics part-time at the University of Queensland and is a visiting lecturer at Seton Hill University in the USA. Peter is one of the editors and authors of the orthodontic textbook, 'Evidence-Based Clinical Orthodontics'. Importantly, he has no financial interest in any products discussed in these Blogs.

MORE ON MYOFUNCTIONALS - 2 CLINICAL TRIALS

Some manufacturers of myofunctional appliances claim that that they achieve better results by treating at a very young age (~5-8 years of age) but what is the evidence? I have Blogged on this topic previously but more recently I came across two unpublished randomised clinical trials (RCT's - which are considered the more robust way of testing a treatment) where they compared myofunctional appliances with conventional functional appliances - so what did they find?

The first was presented at the European Orthodontic Congress in Istanbul- Turkey (Abstract book, scientific poster :361) and was a follow-on from their previous study evaluating comfort of myofunctional appliances where they found the Activator caused less discomfort and was more acceptable than the T4K™ myofunctional appliance  (Eur J Paediatr Dent. 2012;13:219-24). The follow up study evaluated the effectiveness of the appliances and the abstract (found here) presented the results of the 60 patients treated over the 14 months of the study. The authors found that the Activator group showed better skeletal improvement than the myofunctional T4K® group. They also found that the facial convexity improved significantly with the Activator and to a lesser extent with the T4K® while the soft tissue profile was improved only by the Activator. They concluded that the Activator is more effective than the T4K® in treating patients with protrusive upper teeth (Class II division 1).

The second paper was presented at the World Federation of Orthodontists meeting in Sydney (abstract #0335 of this PDF file) and was a multi-centre RCT of 74 subjects comparing another myofunctional appliance with an Activator. Although they found that the prefabricated myofunctional appliances were as effective as Activators in correcting overjet/protrusion, they were less effective in correction of the Class II molar relationship (bite on the back teeth). This implies that the main factor in correction of the overjet/protrusion was only due to tipping of the front teeth as discussed in the previous Blog on myofunctionals (study by Usumez. Angle Orthod 2004;74:605-60). However the advantage with the myofunctional appliance is that no impressions are needed and the cost is less than that of the Activator.

So it would seem that myofunctional appliances have 'some' effect but were less effective than the custom made Activator appliance, particularly in molar/bite correction and skeletal/growth change. This is consistent with the findings of studies discussed in my previous Blog on Myofunctional appliances.

If we are then considering what is the most effective appliance then the custom-made appliances win out but a case could be made where in remote communities with limited or no access to laboratories for impressions or making a custom-made appliance, then perhaps a prefabricated myofunctional appliance can offer some improvement. Both of the main authors of these RCT's are currently PhD candidates and therefore extremely busy people but I also believe they are in the process of writing these papers up for publication which will allow a more thorough read of the trial design and findings.

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia and teaches orthodontics part-time at the University of Queensland and is a visiting lecturer at Seton Hill University in the USA. Peter is one of the editors and authors of the orthodontic textbook, 'Evidence-Based Clinical Orthodontics'. Importantly, he has no financial interest in any products discussed in these Blogs.

WHAT AGE IS BEST FOR ORTHODONTIC TREATMENT TO ACHIEVE THE BEST JAW GROWTH?

Many orthodontic associations around the world recommend an orthodontic exam at age 7 but does this mean your child needs treatment then? There is much debate over what is the best time to treat protrusive upper teeth and/or a retrusive lower jaw (Class II bite like Bart). Some suggest waiting until adolescence (when all adult teeth have erupted), others earlier at age 9-10 with functional appliances such as Twin Blocks, Activators or Bionators, while others suggest even as early as age 5-6 with myofunctional appliances (covered in a previous Blog)!


The evidence supporting very early treatment with myofunctional appliances at age 5-10 is of low quality and that research demonstrates only small clinical changes of ~2mm which for most is not a significant change. Much higher level evidence from well-designed randomised clinical trials have demonstrated that you can treat much worse bites with protrusions of 7mm and more at ages 9-10 but also just as effectively during adolescence when all the adult teeth have erupted (~ages 13-14). The only advantages of treating earlier are in the form of improved self-esteem earlier than if treated later, and a modest reduction in trauma discussed in a previous Blog. Self-esteem can be an important issue for some and a valid reason to consider early treatment.

Some have suggested that you can predict the timing of treatment based upon x-ray markers of growth such as hand-wrist x-rays or more recently using cephalometric radiographs of the skull and identifying the developmental stages of the cervical spine (neck bones), called the CVM method. The CVM method was based upon work by Dr Don Lamparksi from the University of Pittsburgh where I trained and was later revised by others. The timing of peak growth varies widely from 8½-11½ in girls and 10-14 in boys. Research has demonstrated a low agreement in identifying the stages of  these spine markers and that it cannot predict the onset of peak mandibular growth. You would also likely need multiple radiographs to determine when you are actually approaching peak growth and by the time you see it you are already at the peak or past it. But let’s say you do achieve the perfect timing for treatment with an appliance such as a Herbst. In this study evaluating patients treated with a Herbst appliance the authors found that with ideal timing compared with a historical control they found 1.9mm advancement of the chin (Pogonion). Firstly a historical control from over 50 years ago does not allow a valid comparison as the amount and timing of peak growth has changed over the past 50 years. We will also overlook the stability issue in that functional appliance studies always show some early growth effect but that long term the growth slows so there is no difference between those children treated earlier and those treated in adolescence. So now let's compare it to a study using a Herbst in ‘non’-growing adults. They still found a 1.3mm advancement of the chin (Pogonion) so with ideal timing vs. non-growers there is only a 0.6mm advantage! You then have to ask yourself 'Does 0.6mm matter' and most would accept that this is not a clinically meaningful change. Now back to the issue of timing and efficiency - if the treatment time is a little shorter (as growth helps you out a bit more) at the ideal time, then you possibly (and this is unclear) save 2-3 months in overall treatment time compared to treating much earlier or much later This then comes down to whether you consider this potential time saving a big enough benefit to try to determine this most ideal time. However I would not consider it a critical issue.


So why age 7 for a screening exam? Most do not need treatment at this age but it is a good age to identify the small number that would benefit form an early intervention such as early loss of baby teeth that result in space loss, or crossbites of front teeth. Others could be left until age 9-10 e.g. to preserve space to reduce crowding or identify those developing impacting maxillary canine teeth (much easier to intervene at age 9-10 then try to treat a fully impacted canine at age 14-15), while the majority can quite happily wait until all adult teeth have erupted in early adolescence. However your orthodontist does not want to miss the small number that could greatly benefit from such early interventions so if you are unsure then seek a consultation with your orthodontist who can then inform you of the most appropriate treatment time as well as the pros and cons of any options.

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia, editor and author of the textbook Evidence-Based Clinical Orthodontics, and teaches orthodontics part-time at the University of Queensland and is a visiting lecturer at Seton Hill University in the USA.

DO ORTHODONTIC EXTRACTIONS CAUSE SLEEP APNEA?

Sleep apnea (or #apnoea) is a serious condition resulting in excessive daytime sleepiness which can affect concentration and potentially increase accidents. It also increases the risk of high blood pressure, stroke and heart disease. More recently some proponents of myofunctional appliances (see previous Blog) have suggested that extractions can cause sleep #apnea. They state that extractions must reduce the jaw size and therefore the tongue space which in turn, forces the tongue back thereby compromising the airway. This sounds possible in theory but what is the evidence? I'm glad you asked!

It has been claimed that extractions narrow the jaws. Arch dimensions depend upon the points from which you measure them. If you measure the distance between the upper molars before and after closing premolar/bicuspid #extraction spaces then the distance between them does get smaller so it seems the jaw has become narrower. However if you measure between the canine teeth, the measured distance gets larger - what the? This paradox is due to the shape of the jaw being an arch which is wider in the molar region and tapers becoming narrower toward the canine teeth. As extraction spaces are closed, the molars move forward (into the narrower part of the arch) while the canines move back (into the wider part) but the actual arch itself has not necessarily narrowed, it can even have widened depending upon the mechanics and archform used by the treating orthodontist. Depending upon the reason for extractions (e.g. crowding vs. protrusive teeth) the front teeth may or may not move back. For example, if the extraction space is merely used to alleviate crowding, then the arch may not have reduced in size at all. However if the front teeth have been retracted back (to reduce protrusion) then there is potentially less space for the tongue.

Studies looking at patients with protrusive upper and lower teeth requiring extraction of four teeth (two upper and two lower first bicuspids) have varied in their findings. There are a number of limitations to these studies as some use imaging systems which only evaluate in 2-dimensions (x-rays), the subjects are upright and not lying down as we do when asleep (when apnea occurs), and none assess the dynamic changes in the airway with function even if in 3D (e.g. CT) so they only offer a limited appraisal of the subject's airway. Keeping this in mind let's examine their findings. Two studies in American and Arab subjects found no change in the upper airway as did a third study.  However three other studies in Oriental and Indian subjects did find a reduction in the airway size. So why the difference in findings? Apart from random chance, there could be racial differences in the response of the airway to movement of the teeth, or how people in these countries are treated. It has been postulated that craniofacial factors make a larger contribution to the severity of sleep disordered breathing in Chinese than in Caucasians. In addition, a 7th study in Turkish subjects examined trying to retract the teeth a lot (maximum anchorage) vs. not much or none (minimum anchorage) found there was an increase in the airway in the minimum anchorage cases while the maximum anchorage cases where the goal was to retract the front teeth as they were too protrusive did result in a reduction in the airway dimensions. One of the studies found that the reduction in airway seemed to mostly be related to any retraction of the lower front teeth potentially making less space for the tongue. Protrusion of the front teeth is more common in subjects with an Oriental heritage than in those of European ethnicity and so the goal in Oriental subjects undergoing extraction treatment tends to be aimed at greater retraction of the front teeth.

So perhaps extractions where the goal is to retract the front teeth as much as possible may reduce the airway size in some patients. Most orthodontic patients in Western countries are treated without extractions (only ~15-20% in the USA and Australia for example) and an even smaller number of these are treated with four premolars and a minority with maximum anchorage. Blockage of the airway in apnea is not always at the base of the tongue and many are behind the soft palate or velopharynx. What we must also consider is that a reduction in the airway size on an x-ray does NOT mean that you will develop sleep apnea as the airway will still be sufficiently patent for most if not all. Conversely studies using plates have found that despite advancing the lower jaw and potentially increasing the airway, ~13% of subjects actually got worse! Research has also demonstrated that measures of the airway volume or area could not predict who would respond to treatment. Sleep apnea is a complex condition with those highest at risk being middle-aged, over-weight males and the use of alcohol and sedatives can also increase the risk.

What do humans and bull-dogs have in common? We both can suffer from snoring and sleep apnea (well, about 3% of humans do)! Bull dogs are the result of selective breeding (believed to be mastiffs and pugs) resulting in an altered facial and airway form. One theory for humans is that to evolve the ability of speech, this required our jaws to be shorter, the tongue positioned further back and our larynx to descend. Speech was a major advantage and the backward and downward positioning of our faces was not a disadvantage for an animal (that's us humans!) that on average only lived to about 50 years of age until about 100 years ago. However now with many living into their 80's and beyond a backward positioned tongue due to evolution's 'selective breeding' may be placing a small number of us at risk for obstructive sleep apnea (#OSA). Based upon current research we cannot with certainty totally discount that some may be at more risk with extractions, but if there is a risk it would be a small percentage of the subjects that meet the criteria of maximum anchorage and other risk factors so it would be a very small risk indeed if it does exist at all. A recent review article in the Journal of Clinical Sleep Medicine compared patients having had four premolars/bicuspids removed with those having none out and found the prevalence of sleep apnea was not significantly different between groups and concluded that past orthodontic extraction treatment is not supported as a significant risk factor in the cause of obstructive sleep apnea.

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia and teaches orthodontics part-time at the University of Queensland. He is a visiting lecturer at Seton Hill University in the USA as well as lectures internationally. Peter is one of the editors and authors of the orthodontic textbook, 'Evidence-Based Clinical Orthodontics'.

EXPANSION FOR CROSS-BITES

Posterior crossbites where the top back teeth bite inside the lower teeth are relatively common affecting up to ~16% of children with their baby or milk teeth. Crossbites seldom self-correct and so some form of expansion of the top jaw is usually required. We have various options ranging from partial braces with elastics to plates and fixed expanders but what is the most effective way to correct a crossbite?

For a single tooth crossbite your #orthodontist may elect to use buttons and elastics but for multiple teeth they are more likely to choose a removable plate or a fixed #expander such as a quad-helix appliance or a rapid-maxillary expander (RME), also known as a rapid-palatal expander (RPE). Plates can be successful but rely on compliance from the patient with ~20-30% not cooperating - which makes the orthodontists job a bit harder :-/ . Research has demonstrated that the fixed type of expanders (quad-helix, RME/RPE) remove this compliance issue as they are cemented in place and so tend to be more successful and offer slightly more expansion (~1mm).

A posterior #crossbite (circled in green on the right) can result in a slide of the lower jaw to one side on closing creating a bite asymmetry and midline discrepancy (purple lines). Expansion to correct the bite interference can correct some asymmetries (as in this example) while others will have a persistent asymmetry that may require future treatment. Treatment of asymmetries will be the topic of a future Blog. Expansion can also be used to create space as covered in a previous Blog. So if you have a posterior crossbite, visit your orthodontist for them to assess the most appropriate appliance that best suits your needs.

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia and teaches orthodontics part-time at the University of Queensland. He is a visiting lecturer at Seton Hill University in the USA as well as lectures internationally. Peter is one of the editors and authors of the orthodontic textbook, 'Evidence-Based Clinical Orthodontics'.

MYOFUNCTIONAL APPLIANCES - WHAT'S THE EVIDENCE?

Myofunctional therapy is treatment aimed at changing muscle (Myo = muscle) function and possibly influencing jaw growth and the position of the teeth. Myofunctional appliances have been around in various forms for many years. These can include lip shields and screens, eruption guidance appliances and the T4K™.  Although claims are made that they alter muscle function resulting in improved facial growth, better alignment, and more stable results, what evidence is there to support these claims?

There are a number of studies examining the clinical effects of the eruption guidance appliance and the T4K™ and they provide clinical evidence as to the compliance and effect of these appliances.1-5 These appliances are available in a small range of sizes where one is selected to suit an individual rather than being custom made from an impression/scan. Possibly due to this generic fit, one study found 31% of patients did not wear the appliance.1 A randomised trial of the T4K™ vs. a custom made Activator appliance found the Activator caused less discomfort than the T4K™ and was more acceptable.6 All five studies showed that treatment at age 5-9 was quite long (13-36 months) and protrusion of the top teeth was reduced by only a small amount (1.5-2.5mm).1-5 A study of the T4K™ appliance showed it had no growth effect.3 Another study on the eruption guidance appliance followed patients over time and found the small 2mm improvement in crowding relapsed to the initial state which shows it is not stable.4 A 2mm improvement in bite depth was also unstable and relapsed leaving only 0.5mm of change.

A 2mm change is considered a minor improvement and could be treated once all adult teeth have erupted (~age 12-13) in one phase of treatment. This results in a reduced overall treatment time as well as potentially less cost than doing two or more phases of treatment. Clinical trials in the both the USA and the United Kingdom where patients were randomly assigned to early or late treatment have shown that when patients were treated early for much more severe protrusions (7mm rather than 2mm) they could be treated equally as well by delaying treatment until all the baby teeth had been lost.7,8 The result of treating later (~ age 12-13 years of age) was a shorter overall treatment and less cost. However a case can be made for early treatment to reduce protrusive teeth when the appearance or function is concerning the patient or for a small reduction in the risk of trauma to the front teeth (see my previous post on trauma).

So if you are unsure about whether early treatment is required for your child, consult your orthodontist. Some problems such as crossbites and impacted teeth can be detected and treated more effectively if found early. Your orthodontist is an expert in growth and development and can best determine if early treatment or simply monitoring your child is indicated to achieve the most efficient and cost-effective treatment at the most appropriate time.

References:
1. Keski-Nisula. American Journal of Orthodontics & Dentofacial Orthopedics 2008;133:254-60
2. Methenitou. Journal of Pedodontics 1990;14:219-30
3. Usumez. Angle Orthodontist 2004;74:605-60
4. Janson. American Journal of Orthodontics & Dentofacial Orthopedics 2007;131:717-28
5. Myrland et al. European Journal of Orthodontics 2015;37:128-134
6. Idris. European Journal of Paediatric Dentistry 2012;13:219-24
7. Tulloch. American Journal of Orthodontics & Dentofacial Orthopedics 2004;125:657-67
8. O’Brien. American Journal of Orthodontics & Dentofacial Orthopedics 2009;135:573-9

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia and teaches orthodontics part-time at the University of Queensland and is a visiting lecturer at Seton Hill University in the USA. Peter is one of the editors and authors of the orthodontic textbook, 'Evidence-Based Clinical Orthodontics'. Importantly, he has no financial interest in any products discussed in these Blogs.

QUICK OR FAST BRACES - DO THEY EXIST?

Claims of faster treatment are easy to make and we would all like this but is it realistic? In the 1960's and 70's Begg braces/brackets were very popular and were thought to provide faster treatment as they allowed very rapid tipping and alignment. However this was at the price of less control over the root position which took more time to recover later and so they are seldom used nowadays. Other bracket designs that allow tipping have been shown to actually be slower than conventional brackets when closing extraction spaces.

More recently self-ligating brackets such as the Damon bracket, Smart-Clip, In-Ovation, Quick and more were introduced with claims of faster treatment. This was marketed well and became quite popular but with little evidence to support the claims. Dr Miles conducted the first prospective clinical trial and found there was actually no difference during initial alignment which was later confirmed by other researchers. The most recent evidence suggests that despite the claims of faster treatment, the self-ligating brackets may actually be slower than conventional #braces by about 2 months! Braces claiming to be fast are use brackets and wires just like conventional systems and so would not be expected to be any quicker. They claim lower friction but this allows the greater tipping and lack of control seen in earlier systems that proved to be slower. Let's look at an analogy - when you build a house the frame goes up quickly but then seems to slow when the smaller jobs are taking place such as the painting, tiling, etc. - but you don't want to move into your new home without this done do you? The same with braces - the initial alignment of teeth can be quite rapid but these are the simple tipping movements and the roots have not been moved into their correct and more stable positions. Your bite may need correction with elastics or other techniques and this is also a slower movement. These are the ‘detailing’ stages of #orthodontics and are slower and less obvious but very important for the most aesthetic and stable result possible.

The skill of the practitioner in placing the brackets as accurately as possible and using the correct wires, mechanics and appointment intervals affect your treatment duration. However treatment time is also affected by patient cooperation (e.g. are you wearing your elastics as directed?) and biological variation – everyone is different and their teeth move at different rates and respond in varying amounts. The same wire and adjustments will have differing responses in different people and your orthodontist will adjust your treatment based upon what they observe. Even extremely precise methods of bracket positioning using computer-aided design and manufacture, or robotic wire-bending are prone to the same problems of variation in response. Orthodontists are aiming for the best outcome possible for you and this variation is why your #orthodontist cannot give precise times to the eternal question; "When am I getting my braces off?".

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia and teaches orthodontics part-time at the University of Queensland and is a visiting lecturer at Seton Hill University in the USA. Peter is one of the editors and authors of the orthodontic textbook, 'Evidence-Based Clinical Orthodontics'. Importantly, he has no financial interest in any products mentioned in these Blogs.