Corticotomy and rapid orthodontics

Periodontally accelerated osteogenic orthodontics treatment and corticotomy

Hello doctor Chamberland,

I would like to undergo a rapid orthodontic treatment and my orthodontist is proposing an orthodontic treatment with corticotomy.

I would like to get your opinion on corticotomy:

Is it a safe technique?

Is remission good and does the bone become completely normal and viable again?

Is durability of teeth compromised?

In short, are there any risks?

Thanks a lot for your help!

Antoine

Corticotomy-induced accelerated tooth movement

To answer your question well, I will present a summary of an article about corticotomies and rapid orthodontics or accelerated tooth movement published in the American Journal of Orthodontics and Dentofacial Orthopedics in July 2013 in point and counterpoint form. The authors who are in favor are Drs William and Thomas Wilcko and the authors who present the counterpoints, those who are not in favor, are the respected Drs Vincent G Kokich and Dave Mathews.

Effect of a local trauma

Since remodeling of the alveolar bone is a significant element of any orthodontic tooth movement and since bone remodeling is accelerated during the healing of injuries, the idea of making the teeth move faster if the alveolar bone is “injured” locally came early in the history of orthodontics. In the late 1950s, a German surgeon called Köle rekindled the idea that cuts into the alveolar bone between the teeth would accelerate their movement.

More recently, corticotomy-facilitated accelerated tooth movement was analyzed under the angle of a demineralization-remineralization process that produces a regional acceleration of bone remodeling called regional acceleratory phenomenon. To perform corticotomies, the gingiva and the periosteum need to be elevated to expose the bone. The osteotomy cuts are made between the teeth and the bone surface will also be perforated between the osteotomy cuts (figures B and D). The decorticated bone surfaces will be covered with a mixture of demineralized freeze dried bovine bone and plasma rich in blood platelets (figures C and E). The surgical flap is closed and sutured. This new volume of bone facilitates a greater scope of tooth movement toward the areas where bone was absent beforehand. It is recommended to start the orthodontic treatment within one week after the surgery. This kind of procedure is called Periodontally Accelerated Osteogenic Orthodontics therapy or PAOO.

The corticotomy surgery accelerates tooth movement in areas aimed by the surgery because of the demineralization. Facilitated tooth movements will occur only close to the corticotomized teeth. According to the Wilcko brothers, treatment time could be reduced from ⅓ or ¼ of the treatment time that is typically required.

Result of Periodontally Accelerated Osteogenic Orthodontics treatments

No one asks better questions than Dr William Proffit. Therefore, he asks the question from the point of view of the benefit versus the cost and risk of treatment. I will summarize a few points highlighted in the Contemporary Orthodontics volume put in reference.

The first benefit claimed by PAOO is to reduce the treatment time, the second benefit would be arch expansion.

Treatment time

The length of the rapid bone remodeling obtained after decortication is between 2 and 4 months. Tooth alignment, even for the cases showing severe crowding, rarely requires more than 5 months with superelastic shape memory alloy wires. If corticotomy reduces this time to 1 month, the 4-month reduction represents only 20% out of a treatment time of 18-21 months in average.

Risk and cost of treatment

Cost estimate includes all disadvantages of a treatment. Beyond the financial cost, morbidity and complications must be considered. According to Wilcko, teenagers do not suffer from vertical bone loss, but adults can be affected by a vertical loss of alveolar bone. A corticotomy surgery/PAOO is a rather extensive surgery, which led to the modification of the technique where it is no longer necessary to elevate the whole mucoperiosteal flap. Instead, vertical incisions are made to the gingiva between the teeth and bone graft material is inserted under the parts of the undermined flaps.

The financial cost associated with a corticotomy surgery and bone grafting would be almost as high as the cost of the orthodontic treatment itself.

Drs Dave Mathews and Vince Kokich’s counterpoint is even more devastating concerning the efficiency and efficacy of this kind of treatment.

They question the demineralization/remineralization process, because studies were performed in rats, which cannot necessarily be translated to humans. Studies in dogs and cats have not reported the demineralization effect seen in rats. Moreover, a tooth is not moving through the bone; it is the whole alveolus, the ligament and the tooth that are moving. When an alveolar corticotomy is performed near a moving tooth, the cellular response is to increase the number of macrophages which allow earlier resorption of the compressed bone (hyaline) near the ligament. A more rapid tooth movement is possible since the compressed areas are cleaned faster.

How long does the regional acceleratory phenomenon last after a corticotomy?

A study performed in foxhounds shows that the rate of tooth movement peaked between 22 and 25 days after the corticotomy and decelerated afterward. During this 3-week period, the rate was twice as fast.

Similar findings were reported in 13 human adults whose maxillary canines were being retracted after first premolar extractions. Corticotomy was performed on one side only, and the other side was not operated, acting as a control side. During the first 2 months, the rate of tooth movement was twice as fast, reduced to 1.6 times during the third months and the rates of tooth movement were no different in the fourth month.

Therefore, we can conclude that the regional acceleratory phenomenon of the rate of movement is about 4 months.

Does demineralized bone graft incorporate into the cortical plate?

Tomographies seem to demonstrate that a fibro-osseous encapsulation occurs on the outside of the cortical plate rather than an incorporation and augmentation in the cortical plate thickness.

Conclusion

Drs Mathews and Kokich conclude that it is not possible to determine whether periodontally accelerated osteogenic orthodontics / corticotomy is efficacious and efficient. Yes, alveolar corticotomy accelerates the rate of tooth movement. However, one cannot conclude that this accelerated movement invariably translates into reduced orthodontic treatment times.

They believe in:

1- A limited duration of the regional acceleratory phenomenon of the rate of tooth movement.

2- A significant additional financial expense ($$$).

3- Lack of scientific evidence of a significant reduction in orthodontic treatment time.

Now, to answer your questions,

Is it a safe technique?

Yes, it seems like it is a safe technique. It can be compared to another periodontal surgery with flap opening, but cuts are made into the bone that add to the periosteal release of the flap and therefore, the technique leads to further inflammation, swelling and discomfort compared to a normal periodontal surgery.

Is remission good and does the bone become completely normal and viable again?

The remission will be good, but with additional swelling and discomfort. The bone graft material will not necessarily transform into natural bone and a vertical bone loss of 1 mm may occur.

Is durability of teeth compromised?

Not necessarily.

In short, are there any risks?

There are risks, as for any surgery. It is up to you to decide if you are ready to pay 3000$ to 5000$ in addition to the cost of your orthodontic treatment to get it done a few months faster.

Bibliographic references:

1- Contemporary Orthodontics, 5^th ed.  chapter 8. Proffit WR Fields HW, Sarver DM, Elsevier, 2013.

2- Köle H. Surgical operations of the alveolar ridge to correct occlusal abnormalities. Oral Surg Oral Med Oral Pathol 12:515-529, 1959

3- Mathews D.P., Kokich V.G., Accelerating tooth movement: The case against corticotomy-induced orthodontics, AJODO, Vol. 144, Issue 1, p5, Published in issue: July, 2013

4- Wilcko W., Wilcko T., Accelerating tooth movement: The case for corticotomy-induced orthodontics AJODO, Vol. 144, Issue 1, p4.Published in issue: July, 2013