ORTHODONTICS
INTRODUCTION
Modern orthodontics is the branch of dentistry specialized in the diagnosis, prevention and treatment of malocclusions, which show up as anomalies in position and development of jaw bones and teeth.
It also deals with craniofacial growth, the development of dental occlusion and the treatment of dento-facial anomalies.
By means of orthodontics we create a correct alignment for teeth and dento-facial structures both in the growth phase and maturity; also, we create the best possible occlusal matching, a good facial aesthetics, a better health for teeth and their supporting tissues.
OCCLUSION
The term "occlusion" defines the geometric relation between the teeth when maxilla and mandibula close into contact. The classification still most used today is the Angle system:
Class I: ideal ratio between maxilla and mandibula
Class II: the maxilla is up front of the mandibula
Class III: the mandibula is up front of the maxilla.
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It's important to state that these three positions (and their subcategories) are currently considered only anatomical variants, as they are almost equally distributed in the world's population. Therefore it's no longer correct to say that all dental classes other than I are "malocclusions". However, it's true that some of them can potentially cause problems of various kinds to the teeth​ .
ORTHODONTIC ISSUES DURING GROWTH
Most of the dental-skeletal problems observed in growing patients have multifactorial causes (inheritance, defects in embryonic development, trauma and functional influences).
Some behavioral anomalies, the so-called habits, create non harmonic pressure on the orofacial musculature causing the spawning of occlusal problems.
Form and function are closely related to and influence each other: as much 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 so that it won't cause a malocclusion.
Thumb sucking is much more problematic because, if continued beyond 4 years of age, it may create occlusal problems such as anterior open bite with atypical swallowing.
The finger also presses on the palate pushing outwards the upper incisors; the compression of the lip muscles creates a conformation with narrow upper arches.
Oral breathing: it is a pathological situation in which the air passage occurs mainly through the mouth, creating alterations in the neuromuscular system with consequences on the craniofacial shape.
Even atypical swallowing can be considered a bad habit; the tongue thrusts forward and not upwards, and this determines the lack of occlusal contact between arches, the outward position of 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: orthodontics, to solve the malocclusion and myofunctional to give the correct tone to the chewing muscles; Hence, the need for an important collaboration between orthodontist and logopedist.
THE FIRST ORTHODONTIC VISIT
A first orthodontic evaluation is better performed between 4-5 years of age during deciduous dentition because an early evaluation consents to identify the problem and assess its evolution over time.
There are also some malocclusions that must be intercepted early to try to control and possibly neutralize the mechanisms of worsening of the initial defect.
There are some malocclusions for which early interception is considered compulsory:
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Inversion of the anterior occlusion (III class). This situation leads to uncontrolled growth of the mandible with a mechanical obstacle to the normal evolution of the upper jaw.
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Reversal of the lateral-posterior dental match, or unilateral cross 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 room, thus causing a shortening of the arch itself and consequent dental crowding.
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Antero-posterior discrepancies: to be corrected during 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 occlusal 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 usual occlusion position the upper incisors do not cover even the slightest bit the vestibular surface of the lower ones; we have already mentioned that this situation is often linked to bad habits.
When 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, in regards to occlusal problems of skeletal kind, therapeutic possibilities become more limited the more the patient's age advances.
In fact, dento-facial orthopedics can be performed during 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's not a question of a free choice: every device has precise indications!
Removable devices commonly are made of resin and may have various shapes and sizes. The patient has to manage them with care to avoid deformation or breaking.
Fixed devices (braces) 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).
Thanks to bands and brackets, orthodontic arches can be positioned, allowing teeth's movement.
In some phases of the treatment it may be necessary to use auxiliary means such as rubber bands.
Orthodontic brackets can be made of 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 at Stanford University Business School, Zia Chisti and Kelsey Wirth, an invisible orthodontic system called Invisalign was developed: a completely transparent aesthetic aligner able to move teeth.
Putting their knowledge together, the collaboration of orthodontists and CAD / CAM experts was able to create a computerized system that would allow the construction of invisible, sequential plastic shells designed to move the teeth.
The name Invisalign derives from the union of the two English terms "invisible" and "align".
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 kinds 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 has to be officially certified.