Corticotomy as a stage of complex treatment of orthodontic patients. Review.

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In recent years, adult patients are increasingly seeking orthodontic care. Orthodontic treatment has a positive effect on the psychoemotional status of the patient, increases their emotional stability, self-confidence and sociability (1).
There is no clear definition of the term "corticotomy" in the orthodontic literature, which often leads to its confusion with the concept of "osteotomy". It should be noted that a corticotomy is a surgical procedure in which a shallow incision of the cortical plates surrounding the tooth from the cheek and/or tongue is performed. As a result of this procedure, the teeth remain connected to the alveolar segment through spongy bone tissue. In contrast, osteotomy involves the complete separation of the plates from both the buccal and lingual sides, penetrating to the spongy tissue. This can make the dental alveolar segment more mobile. Theoretically, complications after osteotomy may be more likely, including ischemic necrosis of the bone segment, wound defects in the osteotomy area and devitalization of adjacent teeth.
Since the reconstruction of the alveolar bone is the main component of orthodontic tooth movement, and bone remodeling is accelerated during wound healing (2) the idea of faster tooth movement after local injury in the alveolar process first appeared at an early stage in the history of orthodontics. Many specialists have tried to shorten the period of orthodontic treatment in various animal studies and in the clinic, using a variety of techniques with different and not always unambiguous results. Some of these procedures included corticotomy (3), electrical stimulation (4), osteotomy (5), laser exposure (6), vibration (7), cortical incisions (8), piezo-incisions (9). One of the first American dental surgeons Simon P. Hullihan stated in the XIX century. about conducting experiments with the movement of teeth after making incisions in the alveolar bone. However, this approach was not widely adopted for several reasons, including the risk of infection and possibly loss of bone tissue in an era when there were no antibiotics. In the middle of the XX century . The German surgeon Kole revived the idea that incisions between teeth can lead to accelerated tooth movement Alveolar corticotomy is an operative intervention limited to the cortical bone, which is included in the orthodontic treatment plan in order to facilitate the correction of complex occlusive problems (10). In 1981, Frost orthopedist (11) observed that surgical impact It leads to the phenomenon of accelerated local metabolism in the bones near the intervention area (RAP -Regional Accelerator Phenomenon from English. regional accelerator phenomenon, RAP), due to which there is a decrease in bone density and increases the ability to remodel. Such an osteopenic post-surgical condition is described as a temporary phenomenon that gradually passes away as bone density is restored due to physiological calcification (12, 13). The mechanism of action of the RAP effect, which promotes tissue healing, also occurs on the lower jaw (14).
In 2000, brothers M.T.Wilcko and W.M.Wilcko introduced and then improved this combination therapy with surgical and orthodontic methods. They proposed an innovative way to combine corticotomy with alveolar transplantation. Initially, the authors called their unique technology accelerated osteogenic orthodontics (from English. Accelerated Osteogenic Orthodontics, AOO), and then changed the term to Periodontal Accelerated Osteogenic Orthodontics (Periodontally Accelerated Osteogenic Orthodontics, PAOO). This technique involves the use of complex non-removable orthodontic equipment in combination with complete flap folding, as well as buccal and lingual corticotomy around those teeth that require movement. Modern studies have proved that after a corticotomy, the tooth moves faster due to the RAP effect - an accelerated cycle of bone remodeling with a local decrease in its density (15). Thus, the study was able to combine our understanding of the processes of accelerated tooth transposition, corticotomy and surgical decortication, with a focus on the influence of bone demineralization and remineralization parameters during its healing. This model was confirmed during experiments conducted on rats. Thus, the researchers were able to determine that corticotomy does not cause a simple movement of teeth in the structure of the dental alveolar segment under the influence of orthodontic forces, but is a transposition of the entire dental alveolar segment as a whole in the presence of demineralization. A localized RAP effect occurs at the site of surgical injury (15), due to which postoperative bone regeneration occurs faster than normal regeneration. This acceleration is due to the speed of bone tissue healing: it can be 2-10 times faster than normal physiological healing. The initial reaction of the bone to traumatic injury is a biological condition called RAP, characterized by a short-term acceleration of remodeling and a decrease in the density of the trabecular bone (16). Also, this local surge in tissue remodeling is observed after surgical osteotomy or fracture. The reason for faster dental movement is a local and reversible decrease in the density of the bone mineral matrix (or osteopenia), which begins with the initiation of RAP and decreases with the end of RAP. Locally developed osteopenia weakens the trabeculae of the alveolar bone, whose lower resistance subsequently leads to rapid movement of the teeth [17]. As soon as the orthodontic movement is completed, an environment conducive to alveolar remineralization is created around the tooth. The RAP effect begins 2-3 days after surgery, reaches its peak in 1-2 months and lasts, as a rule, 4 months. However, it may take six months or a year before the RAP effect completely disappears (18). With corticotomy, blood circulation in the area of intervention increases, osteogenic processes accelerate, and the amount of bone tissue increases. This study is considered important because it describes the implementation of alveolar decortication in combination with bone transplantation to increase the volume of the alveolar bone and ensure rapid movement of teeth to new expanded areas.
Any injury entails healing, as it interferes with the work of some of the surviving local cells and increases their sensitivity so that they can better respond to specific local and systemic impulses and responses. In addition, trauma triggers local biochemical and biophysical processes that not only prompt cells to react, but also determine the type of this response. The bone remodeling unit or basic multicellular unit (BME) first produces osteoclasts that remove pre–existing hard tissues, and then the BME produces osteoblasts that replace old bone tissue with well-structured secondary tissue, in a typical activation-resorption–formation sequence. Remodeling is a mutual process of resorption and formation of bone tissue. A theoretical assumption has been put forward that such a conjugate mechanism is a means by which the bone is not lost at all during recovery and does not accumulate in excess. At the end of healing, when the RAP stimulus fades, BME activity decreases to a normal level, remodeling spaces are filled with new bone, and osteopenia disappears (19).
In this part of the article, we will consider two well-known methods of corticotomy: piezosurgical and laser. The purpose of surgical intervention on alveolar ridges is to facilitate orthodontic treatment (20). This concept is not new, however, it was only in the late 1990s that the Wilko brothers analyzed the mechanical concept of moving the bone block based on X-ray data from patients who received orthodontic treatment using corticotomy (15).
Then, in 2007, T. Vercelotti and A. Podesta proposed a combination of piezosurgical methods and traditional flap folding for rapid tooth movement. That is, being effective, this method still required detachment of the flap, which did not cancel the risk of postoperative discomfort and complications. Due to shortcomings, both patients and the dental community have negatively accepted this method (21).
Further (22), the authors proposed alternatives-a minimally invasive corticotomy technique, in which incisions are performed without folding the flap. During the operation, the authors penetrated through the gum and cortical layer without lifting either the buccal or lingual flaps, but used an enhanced scalpel and a hammer. This surgical injury, called micro-osteoperforation, is sufficient for the development of RAP effect and rapid movement of teeth. However, the technique has two drawbacks: during the operation, it is impossible to transplant soft or hard tissues in order to correct or strengthen the periodontal, and repeated hammer blows can cause postoperative dizziness. In modern practice, an osteotomy drill is used for micro-osteoperforations (MOS) on a mechanical angular tip with water cooling, the use of which together with local anesthesia does not cause pronounced discomfort.

About the authors

Afsona Sergeenkova

Author for correspondence.
Email: sergeenkova.afsona@gmail.com
ORCID iD: 0000-0002-6789-1552

Nailya Sabitovna Drobysheva

Московский Государственный Медико-Стоматологический Университет им. А.И. Евдокимова

Email: sergeenkova.afsona@gmail.com
ORCID iD: 0000-0002-5612-3451
SPIN-code: 1246-5965

к.м.н. доцент, доцент кафедры ортодонтии МГМСУ им. Евдокимова

References

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