Thursday, 3 June 2010

Accelerated Tooth Movement, short review and future application.

This is how the normal bone remodeling is illustrated with this flash taken from the website of Susan Ott, MD, Osteoporosis and bone physiology. The green is the mineralized bone and the newly formed osteoid is illustrated with red lines. Remodeling is the process that without altering the shape of the bone  is keeping a homeostasis, according to the local needs and mechanical loads.

Accelerated tooth movement is not a new subject in the orthodontic literature and research. The aim is to find an applicable way of shortening treatment time by inducing bone turn-over, remodeling and eventually  displacing teeth with a higher rate, through bone. There is a handful of attempts and approaches suggested up to date.

  • Surgical - invasive technique referred as Wilckodontics, with selective decortication and bone transplant on the regions followed by orthodontic tooth movement. Defects are created with the use of bone bur and the patient is given non NSAID antibiotic and pain relief medication.

The technique is invasive and patients have swelling and bleeding after the operation, however the results are favorable concerning the rate of tooth movement. References and some clinical examples can be found here
  • A slightly less invasive approach is with the use of piezoelectric surgery, where cuts are made on the buccal, cortical bone vertically and horizontally around the teeth of interest.

Still swelling and pain is the main concern here, and a less invasive surgical technique, that in this case does not need bone graft as there is no extensive removal of bone tissue during the operation. The results on tooth movement rate are similar to the Wilckodontics approach.
  • Prostagladines are suggested, to be used  to increase the rate of tooth movement during orthodontic treatment, with results on the actual rate, but extensive root resorptions as a side effect of the treatment.
A few links of studies that show the positive correlation of PGE, accelerated tooth movement and root resorption, (1), (2), (3)
  • Electrical fields suggested to enhance tooth movement rate, by altering the shape of the PDL cells and their membrane polarization.
Articles of E.Steger such as this, advocate of the use of magnets mesial of the 1st molar on the mandible to induce a rapid distalization orthodontically of the tooth. The method and it's application is questionable, with just a few cases published.
  • Circular force application of around 20gr (0.2N) magnitude with 30Hz rate for 20mins per day, is lately advocated in the literature to increase the tooth movement rate, by inducing bone turn over and remodeling. Note that normal masticatory forces have a rate of 1-2Hz and a magnitude that varies from 50-400N.

The application is done through a splint in which the patient bites to, while a motor produces through that splint vibrational low force to the whole dentition. There is a pilot study on 9 patients showing increased tooth movement rates as much as 3mm per month in the mandible. This is the link of this pilot study.
The device is still not FDA approved in the United States it is however in Europe and the main distributer is located at the United Kingdom. This is the official website.

This seems to be the least invasive procedure so far noted in the literature. It's use could be constricted only during closing spaces or large movement periods of the orthodontic treatment, to enhance treatment time.

However the sample is minor and there are side effects like increased saliva secretion, and patient comfort. In addition to that, the long term results of the clinical application of such a device are not yet tested, and as such it should be approached with caution from the orthodontic professional, until more results and data are available. 

Future shows that the accelerated tooth movement is going to be a hot topic around orthodontics and if an easy and efficient way without or with little side effects is introduced, it would be a big break for the orthodontic field.

Literature and References:
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