Combined treatment of malocclusion. Theories of Jaw Growth

Combined apparatus-surgical treatment of malocclusion takes a special place in the practice of an orthodontist. And this exclusivity is associated not so much with the complexity of the treatment as with the need for close interaction between the orthodontist and the surgeon at the stages of rehabilitation. Orthodontic preparation of the patient, as a rule, is relatively simple and not very laborious, and the final stage of orthodontic treatment, provided that the surgical stage is carried out qualitatively, becomes an easy and pleasant task. 

But deciding on such a treatment can be very difficult, both for the patient and the orthodontist. And the fears of one, multiplied by the fears of the other, can be an insurmountable obstacle to the implementation of pathogenetic treatment.  

If in the practice of an orthodontist there are no cases of complex treatment, then the most common explanation is the lack of patients who need such help. Summarizing two years of experience working in a private dental clinic with an orthodontic appointment, we can say that 11.5% of patients remaining for treatment with non-removable equipment agree to a treatment plan that includes reconstructive surgery on the jaw. This is probably one of the highest rates for receiving an orthodontist in an average dental clinic. And this is due to the accumulated personal experience in conducting such treatment and the ability to visualize the benefits of pathogenetic treatment in a large number of clinical cases.  

The aim of this work is to generalize our own experience in the rehabilitation of patients with combined dentofacial anomalies to establish closer ties between surgery and orthodontics clinics. 

To effectively eliminate malocclusion, one should understand the laws of development and growth of the structures that form it, and then the mechanisms of violation of this growth. Despite the large number of studies devoted to this issue, there are still many blank spots in our knowledge of the development and growth of the jaws. It is believed that the development of the facial skeleton is determined by a combination of three growth factors:  

1) biological potency of growth (genetic factor);
2) functional factors of irritation;
3) teething and their stimulating effect on active areas of bone growth.
Various theories describing the growth of the facial skeleton attach more or less importance to one or another factor. 

Theories of jaw growth :
1. Niemann and Shicher – theory of determination of sutures: growth is predetermined genetically, and external and muscle factors are responsible only for its modifications – apposition and resorption.

2. Scott (1956) – the theory of cartilage growth: the primary centers of growth are synchondrosis and cartilage (nasal septum, base of the skull, articular heads of the lower jaw). Sutures are secondary growth centers that do not have independent growth potentials and are activated in response to stimulation emanating from synchondrosis.

3. Van der Klaaw and Moss (1972) – Theory of functional matrices (theory of the functional components of the skull): determining factors are soft tissue pressure, muscle traction, pressure balance in the mouth, nose and sinuses.

4. Petrovic (1982) – the theory of servo systems: the most important condition for the harmonious development of the facial skeleton is occlusion. The sagittal position of the upper dentition is determined by hormonal factors (growth hormone and somatomedins) and tongue pressure. With stable multiple fissure-tubercular contacts, the growth of the lower jaw should be synchronous. With insufficient density of occlusal contacts, the lower jaw receives excess freedom and responds with increased growth of the condylar processes. With excessive extension, blood and lymph circulation in the condylar process is disturbed, which slows down growth. The second level of growth regulation occurs at the level of the central nervous system.

If global theories describing the principles of facial growth of the skull still cause active debate, then the immediate mechanisms are better studied. In order to form an opinion on the formative processes occurring in the jaws, it is necessary to have an idea of ​​the structural changes in the bone tissue of the jaws at the microscopic level. 

event_note September 6, 2019

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