For most orthodontists, many of their current assumptions stem from the work of Charles Tweed. He was a pupil of Edward Angle and was his chosen successor but after working with Angle’s philosophy for some years he found that for some patients there had been significant relapse once the patient stopped wearing their retainers. This was especially evident where there had significant crowding of the teeth before treatment. He then went on to retreat more than 100 relapsed cases but only after he had extracted teeth, usually all the first premolars. Tweed drew up criteria defining what he saw as the parameters for successful orthodontic treatment. He had concluded that you cannot expand the dental arches to any significant extent in either a lateral or antero–posterior direction and then expect stability of the teeth. These assumptions are still prevalent among orthodontists although extraction of teeth is less frequent than in Tweed’s day.
Where the jaw disharmony is considered to be too great, orthognathic surgery combined with suitable orthodontic preparation is widely accepted. This is not usually done until the middle or even the late teens when facial growth is mostly finished.
Until the 1970s, orthodontic treatment using Angle’s edgewise system was technically demanding and most of the intraoral work had to be done by the orthodontist. The successful commercial introduction by Andrews of the Straight Wire Appliance system, using preangulated, pretorqued brackets was truly revolutionary. In one step it transferred to the bracket much of the positioning which previously had to be obtained by the orthodontist adjusting the stainless steel arch wires. The Straight Wire Appliance was rapidly followed by other companies offering similar bracket systems.
As knowledge from space technology filtered down to orthodontic manufacturers, new alloys have come into use for preformed arch wires, giving much more resilience and enabling teeth to be moved over greater distances before an arch change was needed. More innovation in bracket design produced the self-ligating systems which work particularly well with the new arch wires. Yet another innovation has been the bracket design for the Fastbraces system. This uses a triangular design of bracket and specialized arch wire to accommodate to this. It is claimed for this system that up to 80% of malocclusions can be treated in 6 months to one year.
The introduction of computers into orthodontics has helped to change things even more. At first, the computer was used for analysis of radiographs and predictions of facial growth. Orthodontic supply companies have now developed computer applications so that once the clinician has sent in models, radiographs and photos, the company will supply a treatment plan. Then after approval or modification by the clinician, the company will put together a bracket system for indirect bonding with which the clinician can attach the brackets to the teeth. A series of arch wires is also supplied as the case develops.
Two frequent major complaints about fixed brackets or braces are their appearance and the length of time required to obtain a result. Efforts to meet the complaint about appearance have led to innovations such as the Invisalign system which uses a series of removable clear plastic overlays constructed by the company. Each overlay will move the teeth a small amount then is replaced with the next overlay. Thanks to the minimal visibility, ease of wear and extensive advertising by the company this approach has become increasingly common.
The search for ways to shorten the time needed for treatment has prompted other innovations. These take advantage of the fact that suitable stimulation around the site of a wound will encourage a healing reaction. One technique places a series of small perforations into the alveolar bone supporting the teeth. A more radical solution involves stripping the soft tissues away from the alveolar processes, adjusting the exposed bone, then reattaching the soft tissues. Orthodontic braces are then used to move the teeth, which respond much more rapidly than with just the conventional systems. This last technique is said to be more appropriate for adults with compromised periodontal conditions, as bone can be grafted where needed.
It is obvious from even this brief overview that there has been no lack of technical innovation in orthodontics. These innovations have greatly simplified many orthodontic procedures, allowing many of the intraoral adjustments to be done by auxiliary staff such as hygienists. It has also enabled general dentists to undertake orthodontic cases they previously would have referred to an orthodontic specialist. Despite all these changes it is striking that there has not been a comparable effort to make progress in understanding the etiology of malocclusion. There is a broad consensus that malocclusion has both hereditary and environmental components but there is a considerable divergence of opinion as to where the emphasis should be. Many of the current arguments resemble those of the early part of the last century. It is high time for fresh thinking, taking advantage of the remarkable advances in physics and biology now available to us.