Fixed or Removeable that is the Question?

 

Traditionally orthodontics was carried out using removeable appliances. In the early days hickory sticks were strategically placed and the oral moisture made them swell, this expansion put pressure on the tooth causing it to move in an appropriate direction.        It was somewhat unpredictable but it did work to a large extent. It was a technoique which was very limited in what it could achieve but, when there is little else it becomes the treatment of choice.

There is also lots of known cases of the use of a wooden tongue spatula being strategically placed behind an instanding upper anterior soon after eruption to push it over the bite into a normal position. Though how any dentist managed to charge for this treatment is beyond me. And even the use of an acrylic inclined  bite plane fixed in posion on the lower anteriors to move the instanding upper tooth into position was not uncommon in earlier years. I remember making these many years ago out of self cure acrylic – frowned upon later due to the ‘burning ‘ of gingival tissues by the free monomer – I really cannot say I can recall any problems after making them but maybe I have wiped such issues from my memory. These simple, crude appliances did work really quickly but prevented the child from eating very easily. (could be an sset in today’s obese world).  However, as this was only for a short time it was considered acceptable.

This was replaced later by stainless steel wires which were bent into springs of various types and the wire was also used to anchor the appliance to the larger molar teeth using cribs so that only the teeth which were supposed to move did move. Learning to bend the wires into the appropriate shapes was a complete course of itself but some of the technicians became very skilled at this steel version of macramé.

This is where the Adams Crib came into its own as a secure anchor especially for upper teeth. However, because of the angulation of the buccal walls of the lower molars these cribs could be quite difficult to get secure on these teeth and they would often slip off. Necessity being the mother of invention, an orthodontist, Dr Hans Eirew, turned the crib round so that the loop projection was placed on the lingual surface thereby getting secure retention using that undercut but intruding slightly on the tongue space. However, children are, mostly, extremely adaptable and seemed able to accommodate to the intrusion with alacrity.

Removable spring appliances were all fine but they were limited in what they could do because it was very difficult to move teeth bodily to get the best positions. The movements were largely restricted to tilting, intruding, extruding and rotating teeth. Moving teeth backwards against the natural tendency for mesial drift required lots of anchorage using strong 2 or 3 rooted teeth and where these might have been absent or the root structure poor there was some concern that trying to move a canine, which is usually strongly rooted, could cause the molars to drift forwards, possibly closing the space created specially to move the anterior tooth into.

Arch expansion was often done using screws placed in the palate of the divided appliance and advanced in small increments which pushed the teeth out but also caused the bone to widen as the central palatal suture had not yet set in young people so was able to be manipulated into widening the arch shape. The same sort of effect could also be created using a fixed appliance anchored on the molars and using a spring with wires pushing against the cheek teeth to push them out. A minor disadvantage with this method was that it was less controllable than a screw appliance but had the advantage that because it was fixed in place patient compliance was not usually an issue.

A simple Upper Removable Appliance

 

A Removable Upper with a lower bite plane

 

A screw activated expansion plate

 

A functional appliance

As orthodontics developed functional appliances (e.g. Andresen) were introduced which addressed the manoeuvring of both arches at the same time using the forces of occlusion to manipulate the dentition  into the ‘normal’ relationships. The major problems with these appliances were that they were bulky and uncomfortable to wear and they were often not worn so that they were less successful than they ought to have been. When they were worn religiously, as in their native, hardy Scandinavia, they were very successful.

Other functional appliances e.g. the Frankel were also made in one piece and tended to be rather uncomfortable to wear for prolonged periods.

In the UK,  William Clark developed a 2 part functional appliance, the twin block,  designed to be worn 24 hours per day, especially when eating. It was said that eating 1 meal with this appliance system in place was equivalent to wearing it for 24 hours such were the pressures exerted through function. These are still in use today for stimulating guided jaw growth especially relating to class ii malocclusions with a large overjet.

A Twin Block appliance in situ

Then came the development of fixed appliances.

It is well understood that continuous light pressures on teeth makes them move quite quickly but excessive pressure will cause pain and may even cause pulpal death.

Teeth cannot be moved too fast because the process of removal of bone on the side being moved into and laying down of fresh bone in the area from which the tooth is being moved takes time. There is some evidence that if the pressure is continuous the process is speeded up so this makes the fixed appliance ideal as it uses continual light pressure 24 hours/ day. It has another advantage in that it is less dependent on patient compliance.

However, it does require some skill in its use because the wires engage with most of the teeth on a jaw and the pressures are exerted on all the teeth so there is a tendency for all the teeth to move at once.

The later development in about 1960 of Nickel Titanium (NiTi) wires which return to the shape they were formed in regardless of the distortion as they are applied to misplaced teeth has made life easier because the teeth will always be moved towards that original shape provided that there is sufficient space to allow that movement.

NiTi arch wires in place – but using metal

So, the use of NiTi wires has made life a lot easier both for the orthodontists and for those GDPs who want to do some orthodontics.

This is where Oralign comes in; because, as in most things, the real secret of success is the planning which takes place before the treatment. Oralign has GDC Registered  Specialist Orthodontists who diagnose and plan the treatment for you thereby removing the possible pitfalls which many GDPs might not spot but,  which is second nature to an orthodontist. Because we do the planning and we also monitor the treatment we ensure that the GDP keeps away from the complaints departments of either GDC or the courts – Safety is our priority along with success.

The development of ceramic brackets which are transparent and tooth coloured coated wires has further improved the position for adult fixed appliance treatments – the beauty of fixed appliances is that teeth can be moved bodily into any position considered suitable with relative ease.

Transparent brackets with coated NiTi wire

Whilst these brackets and wires are not invisible they are much less obtrusive than the  metal varieties.

Another exciting development has been the introduction of the ‘Transparent’ clear aligner. Created from vacuum formed sheets of thin clear plastic – similar to, but more rigid than, a bleaching tray – the clear aligner gently pressures teeth into the desired position. In use they are almost invisible and they move the teeth in small increments so they are frequently changed as each becomes a ‘loose fit’.

The advent of the digital manipulation of the teeth and the 3D printing of the images created has removed most of the errors associated with the manual method (Kesling Method) of moving the teeth which involved sawing the teeth off the model and repositioning them then creating a new model and repeating the process many times. This was both time consuming and expensive and prone to errors because each time the models were sawn there was loss of tooth tissue on the model which lost accuracy. Hand in hand with this technique came the understanding and widely adopted usage of interproximal enamel reduction (stripping) which facilitated the movement of teeth without the need to create space by extraction.

This was frowned on at first by many in the orthodontic community but has now become accepted as a legitimate method as has the use of aligners to achieve cosmetic results when other possible issues relating to malocclusion are not being addressed as in adult patients simply seeking aesthetics.

These are easy treatments for the GDP to undertake with the requisite planning prior to commencing but do require patient compliance. If they are not worn for the maximum possible time the treatment will be prolonged or, at worst, will fail to complete. At Oralign we suggest that you stress prior to treatment that patient compliance in all aspects of the treatment is essential. And we monitor the treatment as it progresses by getting the GDP to upload photographs at each stage so we can be sure that all is moving as it should.

All in all, adult ‘simple’ orthodontics can be very rewarding both in terms of patient satisfaction, dentist satisfaction, winning new patients by recommendation and additional income.

Whether fixed or removable is selected will be determined by the case – it’s a case of choosing the right horse for the course.

But make sure you have the advice you need all the way through.

Lester Ellman    March 2017

Oralign