Definitions and Descriptions

Modern orthodontics is the branch of dentistry that deals with diagnosticating adn treating malocclusions, showing up in form of anomalies of position and developing of teeth and bones.

Othodontics concerns about the study of the cranio-facial growth, the development of correct dental relations and the treatment of dento-facial anomalies.

By means of othodontics, we aim to create a correct dental line-up and of the dento-facial structures, both in a growth phase as in maturity; create the best occlusal relations possible and obtain the best facial esthetic possible, a better health status for the teeth and their sustaining structures.

All this can be obtained with the application of forces or with the stimulation and redirection of altered functional forces.

By the term "occlusion", we define the contact ratio between teeth when the mandibular and maxillary arches come to contact between them. The classification criteria still most used today is the Angle system, based on the antero-posterior relation between the first permanent molars of the upper and lower jaw.

Simplifying, we can say that:

  • Class I: ideal ratio between maxilla anc mandibula
  • Class II: the maxilla is thrust forward in respect to mandibula
  • Class III: the mandibula is thrust forward in respect to maxilla aaa

  • By "overjet" we mean the distance between upper and lower incisives in antero-posterior direction; its value is normally about 2 mm.

By "overbite" the vertical ratio between inferior and superior incisives is meant: an eccssive vertical superapposition of the superior incisives over the inferior ones, is called a deep bite: the open bite is the lack of contact with beancy between upper and lower incisives.

Most of the dento-skeletal problems found in patients during their growth is boosted by a multifactorial cause (etiology): inheritance, hembrional developing defects, traumas and functional influences.

Some anomalies of behaviour, the so called defective attitudes, create non harmonic pressures on oro-facial muscles, causing the uprising of occlusal problems.

Form and function are strictly entwined between them and are reciprocally conditioned: inso much as a correct function determines a harmonic mouth development, just the like and altered function may deform the dental arches and the maxillary bones.

Let's now analyze these defective attitudes.

The pacifier suction can be considered to be used within the first 24 months of life, so as not to give way to a molocclusion.

Much more problematic is the sucking of the thumb, that, if prolonged over the 4th year, may cause occlusal problems like open bite and atypical deglution.

The finger also presses on the palatine vault, pushing the upper incisives forward. the compression of the perioral muscles, causes a reduction of cross diameters and narrow dental arches.

The oral breathing: this is a pathological situation in which the air passage happens mainly through the mouth and this stimulates neuro muscular alterations with consequences on the cranio-facial shape.

Lips are called incompetent (they don't lock properly) there may be vestibolirized incisives, atypical deglutition with narrow upper jaw.

Also the atypical deglutition can be considered a defective attitude; the tongue's thrust is directed forward and not upwards, and this determines the lack of contact between dental arches, the upper incisives pushed forward, the ogival palate and the lower narrow arch.

It is advisable to do a first orthodontic evaluation between 4-5 years of age, during the deciduous dentition phase, because an early evaluation has the aim of intercepting the problem and predicting its evolution through time.

There are some malocclusions that must be intercepted early, so as to control and eventually neutralize the mechanisms of worsening of teh initial fault.

By interception, we mean the secondary prevention aimed to erase or reduce the negative effects of teh risk factors that already interacted with the patient.

There are some malocclusions that we consider to be of obligatory early interception:

  • Anterior inverted biting (3rd class). this situation brings to a non controlled mandibular growth with a mechanical obstacle to the normal growing evolution of the upper jaw.
  • Inversion of the latero-posterior bite ratio, or monolateral cross bite. In a growing subject, this inversion brings maxillary asymmetry, both on the vertical and horizontal level.

There are also a series of orthodontical problems that can be diagnosed during mixed or definitive dentition:

  • Lack of space: the loss of decisuous teeth at early age represents a risk for teh correct dental allignment because the nearby teeth move along the arch where they find a space and determine a shortening of teh arch itself and the consequent dental crowding.
  • Antero-posterior discrepancies: to be corected in mixed denture if teh problem is scheletrical and therefore needs orthopedic devices to be employed.
  • Vertical discrepancies: deep bite when in the habitual biting position teh upper incisives cover the inferior ones by more than 3 mm. In the most severe cases, it's important that the patient may be evaluated orthodontically.
  • Open bite: When in the abitual biting position, the upper incisives don't cover eben minimally the vestibular surface of the lower ones; We already pointed out that this situation is often bound to defective attitudes.

When othodontic therapy gets necessary, it may be divide in two phases: the forst is the interceptive one, that corrects those dental and scheletrical disharmonies that could complicate future treatments.

This early treatment phase does not eliminate the need of an orthodontic treatment in teh permanent dentition, but it makes it simpler and it helps achieve the best results.

In general, regardin teh cheletrical occlusal issues, we can say that the therapeutical possibilities get more limited the more the patient's age is advanced.

In fact, dento-facial othopedics can be executed while the subject is in his active growing and developing phase; having completed these, the therapeutical weapons in teh hands of the orthodontist are rather limited.

A possibility subsists, of correcting severe malocclusions by means of maxillo-facial surgery.

An orthodontic treatment is based on the use of devices that can be fixed or removable.

This is not a free choice: every device has its precise indications!

The removable devices (that can be worn on and off), are built of resin and have variable shape and dimensions. The patient has to handle them with care so as not to cause deformations or fractures.

The fixed devices are generally made up of bands (metal rings that embrace the tooth and which are cemented to it) and brackets being glued to the teeth's surface by means of adhesive resins.

Thanks to bands and brackets, orthodontic arches can be placed, allowing the movement of the teeth.

In some phases of the treatment, auxiliary items like rubber bands may be employed.

Brackets can be made of metal or ceramic.

In order to meet the increased adult esthetic needs, in 1997, thanks to the idea of two joung students at the Business School of Stanford University, Zia Christi and Kelsey Wirth, a truly invisible orthodontic system, called Invisalign was developed: a series of completely transparent masks designed to move teeth.

Putting together their computer science knowledge, and collaborating with orthodontists and CAD/CAM technicians, they built a computerized system that consented to build transparent sequencial devices by means of which to move teeth.

The name Invisalign comes from the merging of the two words "invisible" and "align".

The Invisalign orthodontic system, was born for patients who bear lowgraded malocclusions, for example crowding in the presence of a posterior stable dentition. The following kinds of defect are within the reach of this system:

  • medium-small diastemas (2-6 mm)
  • medium-small crowdings (4-6 mm)
  • deep or lowly opened anterior bite
  • contracted dental arches that need dental expansion up to 4-6 mm
  • extraction of an anterior tooth to correct crowding

Following clinical experimentation it was also shown that Invisalign can be used also in more complex cases, for example those requiring premolar extraction, molar distalization or the correction af an anterior cross bite.

To be able to use this new technique, the professional must attend a special "certification" course.

Invisalign official site : invisalign