Orthodontics - Invisalign

Orthodontia, also called orthodontics and dentofacial orthopedics, is a specialty of dentistry that deals with the diagnosis, prevention and correction of malpositioned teeth and jaws. Malocclusion is not a disease, but abnormal alignment of the teeth and the way the upper and lower teeth fit together. It can be said that nearly 30% of the population present with malocclusions severe enough to benefit from orthodontic treatment. Orthodontic treatment can focus on dental displacement only, or deal with the control and modification of facial growth.

In the latter case it is better defined as “dentofacial orthopedics”. In severe malocclusions that can be a part of craniofacial abnormality, management often requires a combination of orthodontics with headgear or reverses pull facemask and / or jaw surgery or orthognathic surgery. This often requires additional training, in addition to the formal three-year specialty training anomalies. Typically treatment for malocclusion can take 1 to 2 years to complete, with braces being altered slightly every 4 to 8 weeks by the orthodontist.

There are multiple methods for adjusting malocclusion, depending on the needs of the individual patient. In growing patients there are more options for treating skeletal discrepancies, Methods either promoting or restricting growth using functional appliances, orthodontic headgear or a reverse pull facemask.

Most orthodontic work is started during the early permanent dentition stage before skeletal growth is completed. If skeletal growth has completed, orthognathic surgery can be an option. Extraction of teeth can be required in some cases to aid the orthodontic treatment. Starting the treatment process for overjets and prominent upper teeth in children rather than waiting until the child has reached adolescence has been shown to reduce damage to the lateral and central incisors. However, the treatment outcome does not differ.

Fixed appliances Currently, the majority of Orthodontic Appliance Therapy is delivered using fixed appliances, with the use of removable appliances being greatly reduced. The treatment outcome for fixed appliances is significantly greater than that of removable appliances as the fixed type produces biomechanics that has greater control of the teeth under treatment: being able to move the teeth in dimensions therefore the subsequent final tooth positions are more ideal. Fixed orthodontic appliances aid tooth movement, and are used when a 3-D movement of the tooth is required in the mouth and multiple tooth movement is necessary. Ceramic fixed appliances can be used which more closely mimic the tooth colour than the metal brackets. Some manufacturers offer self-litigating fixed appliances where the metal wires are held by an integral clip on the bracket themselves.

The Nature of Maxillofacial Trauma

The underneath surface of an upper Wrap Around Hawley retainer resting on top of a retainer case

The best-known removable retainer is the Hawley retainer, which consists of a metal wire that typically surrounds the six anterior teeth and keeps them in place. Named for its inventor, Dr. Charles A. Hawley, the labial wire, or Hawley bow, incorporates 2 omega loops for adjustment. It is anchored in an acrylic baseplate that sits in the palate (roof of the mouth). The advantage of this type of retainer is that the metal wires can be adjusted to finish treatment and continue minor movement of the anterior teeth as needed. It also benefits from being robust and rigid, easy to construct, and allows prosthetic tooth/teeth to be added onto. The main disadvantages of this type of retainer are its inferior aesthetics, interference with speech, risk of fracture, and inferior retention of lower incisors in comparison to vacuum-formed retainers.

Recently, a more aesthetic version of the Hawley retainer has been developed. For this alternative, the front metal wire is replaced with a clear wire called the ASTICS. This retainer is intended to be adjustable similarly to the traditional Hawley retainer, which is not practical with vacuum-formed retainers. The original clear bow named QCM was developed to eliminate the look of wire across the facial surface of the arch. Excessive breakage has made this impractical for younger patients.

Vacuum-formed (Invisible/Trutain/Essix) retainer

Another common type of removable retainer is the vacuum formed retainer (VFR). This is a polypropylene or polyvinylchloride (PVC) material, which is more economical and faster to make, typically .020″ or .030″ thick. Essix (invented by John Sheridan) and Zendura are the brand names commonly associated with this retainer. This clear or transparent retainer fits over the entire arch of teeth or only from canine to canine (clip-on retainer) and is produced from a mold. It is similar in appearance to Invisalign trays, though the latter are not considered “retainers.” The retainer is virtually invisible and clear when worn. Hence, it can provide aesthetics value to the patient. VFRs, if worn 24 hours per day, do not allow the upper and lower teeth to touch because plastic covers the chewing surfaces of the teeth. Some orthodontists feel that it is important for the top and bottom chewing surfaces to meet to allow for “favorable settling” to occur.

Besides that, it is advisable to wear VFRs only at night, every night.[4] When eating is necessary, the retainer is removed to allow natural consumption and to avoid the crushing of the VFR. Patient should be informed never to drink, especially cariogenic or fizzy drinks, with VFR in situ as it will lead to substantial loss of tooth surface and dental caries. The retainer can behave like a reservoir, enclosing the incisal edges and cuspal tips with the cariogenic drink, leading to decalcification of teeth.[4] VFRs are less expensive, less visible, and easier to wear than Hawley retainers; however, for patients with disorders such as bruxism, VFRs are prone to rapid breakage and deterioration, especially if the material is PVC, a short chain molecule which breaks down far more quickly than polypropylene, a long chain molecule.

Most removable retainers are supplied with a retainer case for protection. During the first few days of retainer use, many people experience extra saliva in their mouth. This is natural and is due to the presence of a new object inside the mouth and consequent stimulation of the salivary glands. It may be difficult to speak for a while after getting a retainer, but this speech difficulty should go away over time as one gets used to wearing it.

Fixed retainers

An entirely different category of orthodontic retainers are fixed or bonded retainers. There are many different types of fixed retainers, which include : • Reinforced fibres

• Fixed canine and canine retainer (only bonded to canine teeth)

• Multi-strand retainers (bonded to every tooth)

Fixed retainers An entirely different category of orthodontic retainers are fixed or bonded retainers. There are many different types of fixed retainers, which include : • Reinforced fibres

• Fixed canine and canine retainer (only bonded to canine teeth)

• Multi-strand retainers (bonded to every tooth)

Multi-strand stainless steel wire retainers are bound to every tooth in the labial segment, using composite resin or acid-etch composite bonding. Fixed canine and canine retainer are bonded only to the canine teeth; as a result, relapse of the incisors may occur. Reinforced fibre retainers tend to fracture commonly. In order to prevent minor unwanted tooth movement, the fixed retainer must be passive.

A fixed retainer typically consists of a passive wire bonded to the lingual-side of the (usually, depending on the patient’s bite, only lower) incisors. Unlike the previously-mentioned retainer types, fixed retainers cannot be removed by the patient. Some doctors prescribe fixed retainers regularly, especially where active orthodontic treatments have affected great changes in the bite and there is a high risk for reversal of these changes. While the device is usually required until a year after wisdom teeth have been extracted it is often kept in place for life. Fixed retainers may lead to tartar build-up or gingivitis due to the difficulty of flossing while wearing these retainers. As with dental braces, patients often must use floss threaders to pass dental floss through the small space between the retainer and the teeth

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