ORTHODONTICS
INTRODUCTION
Modern orthodontics is the branch of dentistry specialized in the diagnosis, prevention and treatment of malocclusions, which manifest themselves as anomalies in the position and development of the jaw bones and teeth.
It also deals with craniofacial growth, the development of dental relationships and the treatment of dento-facial anomalies.
With orthodontics we want to create a correct alignment of the teeth and of the dento-facial structures both in the growth phase and in maturity; create the best possible occlusal relationships and obtain a good facial aesthetics, a better state of health of the teeth and their supporting tissues.
OCCLUSION
The term "occlusion" defines the relationships between the dental elements when the maxillary and mandibular arches come into contact with each other. The classification criterion still most used today is the Angle system:
Class I: ideal ratio between maxilla and mandible
Class II: the maxilla is ahead of the mandible
Class III: the mandible is ahead of the maxilla.
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It is important to underline that these three positions (and their subcategories) are currently considered only anatomical variants, as they are almost equally distributed in the world population. It is therefore no longer correct to state that all dental classes other than I are "malocclusions". However, it is true that some of them can potentially (in the long run) cause problems of various kinds to the teeth​ .
DEVELOPMENT OF ORTHODONTIC PROBLEMS
Most of the dental skeletal problems encountered in growing patients are supported by a multifactorial cause (hereditary causes, defects in embryonic development, trauma and functional influences).
Some behavioral anomalies, the so-called spoiled habits, create disharmonic pressures at the level of the orofacial musculature causing the appearance of occlusal problems.
Form and function are closely related to each other and condition each other: just as a correct function determines a harmonious development of the mouth, so an altered function can modify the shape of the jaws and dental arches.
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Sucking with a soother can be considered advisable for the first 24 months of life so that it does not create a malocclusion.
Thumb sucking is much more problematic, which if continued beyond 4 years of age can create occlusal problems such as anterior open bite with atypical swallowing.
The finger also presses on the palate pushing the upper incisors outwards; the compression of the lip muscles creates a conformation with narrow upper arches.
Oral breathing: it is a pathological situation in which the passage of air occurs mainly through the mouth, which creates alterations in the neuromuscular system with repercussions on the craniofacial shape.
Even atypical swallowing can be considered a bad habit; the thrust of the tongue goes forward and not upwards, and this determines the lack of occlusal contact between the arches, the outward position of the upper incisors, the high pointed palate and the rather narrow lower arch.
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​ The correction of these functional problems must be twofold: orthodontic, to solve the malocclusion and myofunctional to give the correct tone to the chewing muscles; from this we understand the need for an important collaboration between orthodontist and speech therapist.
THE FIRST ORTHODONTIC VISIT
It would be better to make a first orthodontic evaluation between 4-5 years in the full phase of deciduous dentition because an early evaluation is aimed at identifying the problem and assessing its evolution over time.
There are also some malocclusions that must be intercepted early to try to control and possibly neutralize the mechanisms of aggravation of the initial defect.
There are some malocclusions that we consider compulsory early interception:
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Inversion of the anterior chewing (III class). This situation leads to uncontrolled growth of the mandible with a mechanical obstacle to the normal growth evolution of the upper jaw.
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Reversal of the lateral-posterior coupling, or unilateral cruciate bite. In the growing subject, this inversion involves an asymmetry of the maxilla both in the transverse and vertical planes.
Then there are a whole series of orthodontic problems that can be diagnosed in the mixed or permanent dentition phase:
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Lack of space: the loss of deciduous teeth at an early age represents a risk for correct dental alignment because the neighboring teeth move along the arch where they find the space causing a shortening of the arch itself and consequent dental crowding.
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Antero-posterior discrepancies: to be corrected in mixed dentition if the problem is skeletal and therefore needs to be solved with orthopedic devices.
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Vertical discrepancies: deep bite when in the usual occlusion position the upper incisors cover the vestibular surface of the lower ones by more than 3 mm. In severe cases it is important that the patient be examined for an orthodontic evaluation.
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Open bite: when in the usual occlusion position the upper incisors do not cover even the slightest bit the vestibular surface of the lower ones; we have already said that this situation is often linked to bad habits.
When it is necessary, orthodontic therapy can be divided into two phases: the first phase is the interceptive one that corrects those dental and skeletal disharmonies that could considerably complicate future treatments.
This early stage of treatment does not eliminate the possible need for permanent dentition orthodontic therapy, but makes it easier and optimizes the results.
In general, as regards the occlusal problems of the skeletal type, it can be said that the therapeutic possibilities become the more limited the more the patient's age advances.
In fact, dento-facial orthopedics can be performed when the subject is in phase active growth and development; when growth is complete, the therapeutic weapons available to the orthodontist are rather limited.
However, there is always the possibility of correcting serious malocclusions with maxillofacial surgery.
THE ORTHODONTIC EQUIPMENT
Orthodontic treatment involves the use of equipment that can be fixed or removable.
It is not a question of a free choice: every device finds precise indications!
Removable appliances commonly called furniture (because they are put on and taken off), are made of resin and can have various shapes and sizes. The patient must treat them with care to avoid deformation or breakage.
Fixed appliances generally consist of bands (metal rings that embrace the tooth and are cemented to it) and brackets (attachments that are glued to the surface of the teeth using adhesive resins).
It is thanks to the bands and brackets that orthodontic arches can be positioned that allow the movement of the teeth.
In some phases of the treatment it may be necessary to use auxiliary means such as rubber bands.
Orthodontic brackets can be metal or ceramic.
THE INVISALIGN SYSTEM
To meet the greater aesthetic needs of adult patients, in 1997, thanks to an idea of two young students of the Stanford University Business School, Zia Chisti and Kelsey Wirth, a truly invisible orthodontic system called Invisalign was developed: a completely transparent aesthetic aligners able to move the teeth.
Putting their computer knowledge together, the collaboration of orthodontists and CAD / CAM experts were able to create a computerized system that would allow the construction of truly invisible, sequential appliances with which to move the teeth.
The name Invisalign derives from the union of the two English terms "invisible" and "align" which mean to align invisibly.
The Invisalign orthodontic system was created for patients with mild malocclusions, for example frontal crowding in the presence of stable posterior teeth. Patients with the following types of malocclusions are also included in the indications of the system:
medium-small diastemas (2-6mm)
medium-low crowding (4-6mm)
deep anterior or slightly open bite
contracted dental arches that require dental expansion up to 4-6mm
extraction of an anterior tooth in the lower arch to correct crowding.
However, following clinical trials, it has been shown that Invisalign can also be applied in more complex cases that require, for example, the extraction of premolars, the distalization of molars or the correction of an anterior cruciate bite.
To use this new technique, the practitioner must participate in a special "certification" course.