Occlusion, in a dental context, means simply the contact between teeth. More technically, it is the relationship between the maxillary (upper) and mandibular (lower) teeth when they approach each other, as occurs during chewing or at rest.
Malocclusion is the misalignment of teeth and jaws, or more simply, a "bad bite." Malocclusion can cause number of health and dental problems.
Static occlusion refers to contact between teeth when the jaw is closed and stationary, while dynamic occlusion refers to occlusal contacts made when the jaw is moving, as with chewing.
Centric occlusion is the occlusion a person makes when they close their jaw and fit their teeth together in maximum intercuspation. It is also referred to as a person's habitual bite, bite of convenience, or intercuspation position (ICP). Centric relation, not to be confused with centric occlusion, is a relationship between the upper and lower jaw.
Angle's classification method
Edward Angle, who is considered the father of modern orthodontics, was the first to classify malocclusion. He based his classifications on the relative position of the maxillary first molar.[1] According to Angle, the mesiobuccal cusp of the upper first molar should rest on the mesiobuccal groove of the mandibular first molar. Any variations from this resulted in malocclusion types. It is also possible to have different classes of maloclusion on left and right sides.
It is estimated that approximately 18% of the United States population suffers from an over sided malocclusion, while only 11% suffer from an under malocclusion.[citation needed]
- Class I: Here the molar relationship of the occlusion is normal or as described for the maxillary first molar, but the other teeth have problems like spacing, crowding, over or under eruption, etc.
- Class II: ("overbite") In this situation, the upper molars are placed not in the mesiobuccal groove but anteriorly to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. There are two subtypes:
- Class II Division 1: The molar relationships are like that of Class II and the anterior teeth are protruded.
- Class II Division 2: The molar relationships are class II but the central are retroclined and the lateral teeth are seen overlapping the centrals.
- Class III: (prognathism, "underbite" or "negative overjet") is when the lower front teeth are more prominent than the upper front teeth. In this case the patient has very often a large mandible or a short maxillary bone.
Malocclusion and Orthodontics - Treatment Overview
Orthodontic treatment uses appliances, teeth removal, or surgery to fix the way teeth and jaws are aligned. There are many ways to treat poor bite (malocclusion). Expert opinions differ about when to start treatment. Your dentist or orthodontist may give you a choice between early or later treatment or may prefer one specific approach.
The general categories of orthodontic devices (appliances) are functional and fixed.
Functional appliances use the muscle action from speaking, eating and swallowing to create forces that move teeth and align the jaws.
- Some functional appliances are removable, while others are bonded to the teeth.
- A functional appliance may fit between the upper and lower teeth (a splint) or may span across the mouth between the molars, pressing the bone outward.
- Headgear can attach to bands on the teeth to speed up treatment time.
Fixed orthodontic appliances are sets of wires and brackets cemented to the teeth. These are commonly called braces . Over a period of about 24 to 28 months, the wires are tightened and adjusted, gradually applying enough force to move the teeth (bone remodeling).
Retainers are removable appliances made of molded plastic and wire. They hold the teeth in place after braces are taken off. If the teeth start to move back out of position, the orthodontist may bond a short retaining wire to the back of some teeth. This will hold the teeth in place until the wire is removed.
Child and adolescent treatment
The aim of treatment in the childhood and teen years is to move permanent teeth into place. The orthodontist will time the treatments to match your child's natural growth spurts.
Treatment for crowding, the most common malocclusion problem, may mean removing (extracting) some permanent teeth, but orthodontists avoid removing permanent teeth when they can.
The malocclusion treatments for children and adolescents are:
- Extraction (serial removal). Removing some baby teeth may ease severe crowding.
- Growth modification. This involves wearing fixed or functional appliances during the day and night to move the jaw into a better position.
- Fixed appliances (braces) gradually move the teeth. For children and teens, this treatment phase usually lasts about 24 months; for adults, about 28 months.
- Retainers. Retainers hold the teeth in place after orthodontic treatment. Some orthodontists recommend that retainers be worn for many years, because teeth have a natural tendency to drift out of place.
- Space maintainers, made of metal or plastic. Spacers keep the surrounding teeth from moving (drifting) into open spaces created when teeth are pulled or lost in an accident.
Adult treatment
Orthodontic treatment for malocclusion is a popular option for adults, due in part to better technology. In the past, wide silver bands held braces in place. Today they are less obvious. Instead of the wide bands, a small metal or ceramic fastener is bonded to each tooth, and a narrow wire passes through the fasteners.
New options include:
- Clear plastic instead of silver wires.
- Lingual braces. These braces attach to the back of the front teeth.
- Removable clear plastic aligners (Invisalign). These are molded specifically for you.
Lingual braces and aligners don't work for everyone. They aren't options for children. Your orthodontist can tell you the best choices for your situation.
Orthodontic treatment for adults may also involve:
- Removal (extraction) of teeth to create more space.
- Orthognathic surgery of the jaw.
- A retainer, after braces are removed.
- Adjustments, such as grinding of high tips of teeth, to prevent continued or increased malocclusion for adults.
Most adults have little or no jaw growth. This means that surgery is the only way to correct jaw-related bite problems. Some adults may benefit from simply camouflaging, or hiding, a jaw-related problem. Using braces, the orthodontist can move the teeth so that they fit together, despite the jaw discrepancy.3 However, surgery is the best way to treat more severe jaw problems.
What To Think About
Some cases of malocclusion clearly require orthodontic treatment to straighten teeth. In many cases, however, the decision is a matter of personal choice. Besides looking nice, straight teeth can improve how you bite, chew, and speak. They are also less prone to decay, gum disease, and injury.
The timing of treatment is ultimately up to you and your child or teen. Talk to your orthodontist about the pros and cons of treatment options.
Orthodontic treatment isn't an exact science. The average treatment time is about 2 years, but it can take longer than planned.4 Usually, adult treatment takes longer than a child's treatment. The treatment time can vary, so ask your dentist how long it may last for you.
After treatment ends, teeth often begin to shift. Molded plastic retainers, usually worn at night, help prevent this tooth movement. You may need a retainer for an indefinite period of years.
Orthodontic treatment is costly. Most medical and dental insurance plans don't pay for orthodontics. Before deciding on treatment, ask about the projected cost, terms of payment, and terms of the treatment contract.
Orthodontic treatment doesn't pose risks to adults who have healthy teeth and gums. Adults who have gum (periodontal) disease, however, must first get treatment from a periodontist to avoid possible gum damage or tooth loss. Orthodontic treatment sometimes can worsen preexisting conditions.
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