Also called: Crooked Teeth, Dental Malocclusion, Misaligned Teeth
Kenneth Cheng, D.D.S.
Malocclusion is any condition in which a person’s upper and lower teeth and jaw do not fit together properly. People with malocclusion may have trouble biting, struggle to keep teeth clean and experience health problems related to gum tissue. Malocclusion also can affect jaw growth, speech development and a person’s appearance.
Although malocclusion can cause various types of tooth and jaw abnormalities, most conditions can be grouped according to one of three categories. They are:
- Class I. Bite is normal but teeth may still be crowded or otherwise malpositioned.
- Class II. Upper jaw and teeth overlap the bottom jaw and teeth.
- Class III. Lower jaw protrudes forward. Lower teeth extend over upper teeth.
In most cases, malocclusions are developmental. A person may have malocclusion if the upper and lower jaws are not the same size. Or, malocclusion may result if a person’s mouth is especially small, causing teeth to become crowded and shift out of position.
However, other malocclusions can be acquired through certain situations, including accidents, illnesses and other problems associated with dental restorations, prolonged thumb sucking or use of a pacifier, premature loss of primary teeth, or tongue-thrusting.
Malocclusion usually causes symptoms that do not appear right away, but instead gradually develop over time. These may include chewing difficulties, tooth decay, gum disease, fractures of crowns or loosening of the teeth. It may also result in low self-esteem due to a facial appearance that is considered unusual or unattractive by conventional standards.
Typically, a dentist uncovers the nature of a patient’s malocclusion through a dental examination during childhood. If the dentist suspects malocclusion, the patient will be referred to an orthodontist. The orthodontist also will take dental x-rays and take impressions of the teeth using rubbery material. Photographs of the patient’s face and teeth also may be taken to trace how treatment changes the child’s facial appearance.
After these steps have been taken and all relevant information has been gathered, a treatment plan will be formulated. Malocclusion typically is treated using fixed or removable appliances, or a combination of both. Fixed appliances are known as braces and are the most common form of treatment for malocclusion. Removable appliances, which are composed of wires attached to a plastic base (e.g., retainer), can be removed by the patient.
Other treatments for malocclusion include adjusting, reshaping, bonding or capping rough or irregular teeth. If restoration work is the source of the malocclusion, the restoration may have to be fixed or replaced. In some cases, surgery may be necessary to correct malocclusion.
Malocclusion is any condition that results in an incorrect bite. It occurs when a person’s upper and lower teeth and jaw do not fit together properly. Malocclusion is a term that comes from Latin and means “bad bite.”
A perfect bite is one where the top teeth fit slightly over the lower teeth. The cusps or points of a molar – which are found in both the top and bottom rows of teeth – fit in the opposite molar in a specific way. Teeth should be aligned, straight and proportionally spaced. When a bite is correct, the upper teeth protect the lips and cheeks from being bitten, while the lower teeth protect the tongue.
Few people have a perfect bite (occlusion). Many have minor malocclusions that do not require orthodontic treatment. However, some people have abnormalities that are significant enough to cause problems. People with malocclusion may have trouble biting, struggle to keep teeth clean and experience health problems related to gum tissue. Malocclusion also can affect jaw growth, speech development and a person’s appearance.
There are no standard criteria for treating malocclusion. Dentists and orthodontists generally treat the condition if patients experience symptoms related to their bite, or when abnormalities in the patient’s bite increase the risk of future problems unless corrective treatment is undertaken.
Malocclusion can cause various types of problems with the teeth and jaws. Some of the most common include:
- Crossbite. Most common type is when the upper teeth bite or occlude inside of the lower teeth. This can cause biting and chewing problems.
- Crowded or crooked teeth. Poor alignment of the teeth can occur as a result of a dental arch that is too small, teeth that are too large or a combination of these factors. Teeth may become impacted or biting may be affected. Crowded or crooked teeth also can be cosmetically unappealing.
- Open bite. Occurs when the upper and lower incisor teeth do not touch during biting. This places all chewing pressure on the back teeth, making chewing less efficient and causing excessive wearing of the back teeth.
- Overbite. The upper jaw is larger than the lower jaw, leading to discomfort, bone damage and excessive wear of the front teeth.
- Protruding upper teeth. These teeth are more prone to injury and may indicate unevenness in jaw growth. They also may indicate a poor bite of the back teeth.
- Spacing. A wide dental arch or missing or small teeth can cause gaps between the teeth, which may be considered cosmetically unappealing.
- Underbite. Lower jaw is bigger than the upper jaw, resulting in lower front teeth that protrude and a possible crossbite.
Patients receive numerous benefits from treatment to correct bite or occlusal abnormalities of their teeth or jaws. Treatments can significantly reduce or eliminate excessive strain on the teeth, jaws and muscles. This lessens the risk of breaking a tooth and reduces the likelihood of developing symptoms associated with temporomandibular joint disorders.
Teeth that are straight or properly aligned are easier to brush and floss, which reduces the risk of tooth decay and gum disease. Teeth that do not protrude are less likely to be injured during a fall or other minor mishap. A proper bite also can help people to chew and digest their food more efficiently, which can prevent malnutrition.
Treatment can also help correct speech difficulties and can prevent the back teeth from wearing down as a result of an inaccurate bite. Finally, treatment to correct a misaligned bite can improve a patient’s appearance, leading to enhanced self-esteem.
Types and differences of malocclusion
Although various abnormalities can cause malocclusion, most conditions can be grouped according to one of three categories. They are:
- Class I. Occurs when the bite is normal but the teeth may still be crowded or otherwise malpositioned. It is the most common form of malocclusion.
- Class II. Occurs when the upper jaw and teeth overlap the bottom jaw and teeth. Also called retrognathism or overbite.
- Class III. Occurs when the lower jaw protrudes forward and the lower teeth extend over the upper teeth. Also called prognathism or underbite.
Potential causes of malocclusion
In most cases, the source of a malocclusion is developmental. A person may have malocclusion if the upper and lower jaw are not the same size. Or, malocclusion may result if a person’s mouth is especially small, causing teeth to become crowded and to shift out of position. Malformed teeth, impacted teeth and teeth that erupt in an abnormal fashion can all cause malocclusion.
In addition, nearly 25 percent of craniofacial abnormalities that affect oral development are associated with mental retardation, according to the National Institutes of Health. These problems can include malocclusion, extra or malformed teeth and developmental tooth defects. Genetic conditions that cause cerebral palsy and cleft palate also are likely to result in bite problems.
However, other malocclusions can be acquired through certain situations, including:
- Accidents. Teeth that are fractured or knocked out and reimplanted may fuse with the bone around them (ankylosis) following replacement. This prevents the teeth from lining up properly in the jaw of growing children, resulting in an irregular bite.
- Illnesses and other problems. Dental disease and problems that develop after birth (e.g., air obstruction by tonsils and adenoids) can cause malocclusions. Tumors of the mouth or jaw also can cause malocclusion.
- Problems associated with dental restorations. Improper fit of certain types of dental work can cause malocclusion. These include fillings, crowns, appliances, retainers or braces. Misalignment of jaw fractures following a severe injury also can cause malocclusion.
- Prolonged thumb sucking or use of a pacifier. Children who engage in either of these habits after their permanent teeth erupt about age 6 or 7 can force the upper teeth to protrude over the lower teeth. Thumb sucking and pacifier use in younger children may not significantly increase the risk of malocclusion.
- Premature loss of baby teeth. When a primary tooth is lost too early, it can cause the emerging permanent tooth to drift or erupt incorrectly. Some primary teeth are lost due to tooth decay. In certain cases, adjacent primary teeth may move into the gap left by the tooth that was lost early. This can prevent the permanent tooth from coming in.
- Tongue-thrusting. A long-term habit of pushing the tongue onto the back of the front teeth during swallowing can cause the teeth to protrude.
Signs and symptoms of malocclusion
Malocclusion usually causes symptoms that do not appear right away, but instead gradually develop over time. These may include chewing difficulties that can lead to malnutrition in some patients. Patients with teeth that are not correctly aligned are at greater risk for tooth decay because it is more difficult to properly brush and floss crooked teeth. Misaligned teeth also force some teeth to absorb extra strain during biting, which can result in fractures of crowns or loosening of the teeth.
Other symptoms of malocclusion include:
- Difficulty biting or chewing
- Mouth breathing, in which the patient breathes without closing the lips
- Speech difficulties
Finally, many patients with malocclusion may have a facial appearance that is considered unusual or unattractive by conventional standards. This can lead to feelings of low self-esteem.
Diagnosis methods for malocclusion
Typically, a dentist uncovers the nature of a patient’s malocclusion through a dental examination that includes a review of the patient’s dental history. Typically, the dentist will retract the patient’s cheek outward and ask the patient to bite down normally. This allows the dentist to see if the patient’s bite is correct. In most cases, malocclusion can be spotted by the time a patient’s permanent teeth begin to erupt, which may take place as early as 6 or 7 years of age.
If the dentist suspects malocclusion, the patient will be referred to an orthodontist. This is a dentist who specializes in diagnosing and treating misaligned teeth and jaws. Malocclusion is the most common reason for referrals to orthodontists.
The orthodontist also will perform an inspection of the patient’s teeth and mouth to further pinpoint the nature of a patient’s malocclusion. Dental x-rays will be taken. A panoramic x-ray captures an image of all the upper and lower teeth in biting position, and a lateral x-ray of the entire head (cephalometric x-ray) captures the relationship of the teeth and jaws to the rest of the face.
Impressions of the teeth are taken by having the patient bite down on a soft rubbery material that hardens. These impressions are used to create a plaster model that duplicates the patient’s bite. This model can be used as a baseline reference against which the patient’s progress is monitored. Photographs of the patient’s face and teeth also may be taken to trace how treatment changes the person’s facial appearance.
After these steps have been taken and all relevant information has been gathered, a treatment plan will be formulated.
Treatment options for malocclusion
Whenever possible, it is best to diagnose and treat malocclusion at a young age, when the bone is still soft and teeth can be moved more easily. Malocclusion may be treated in steps in children so that each therapy coincides with a child’s level of growth and development. However, treatment is often successful at any age.
Malocclusion typically is treated using fixed or removable appliances, or a combination of both. Fixed appliances are known as braces, and they are the most common form of treatment for malocclusion. Braces involve moving the teeth into proper position through a system of brackets and wires that pressures teeth to shift in a certain direction.
Removable appliances are composed of wires attached to a plastic base and can be removed by the patient. For example, a patient may be asked to wear a retainer that can be removed. Head and neck gear are other examples of removable appliances. This gear has wires that attach inside the mouth. These devices typically are used in situations when extra tension is needed to straighten out a patient’s teeth or jaw. The success of these devices is highly dependent upon the patient’s willingness to closely follow a dentist or orthodontist’s treatment plan. Regardless of the treatment method, careful adherence to the recommended schedule for brushing and flossing is essential for success and the prevention of complications.
Other treatments for malocclusion include adjusting, reshaping, bonding or capping rough or irregular teeth. If dental restoration work is the source of the malocclusion, the restoration may have to be fixed or replaced.
In some cases, surgery may be necessary to correct malocclusion. This is particularly true of adults, who may have skeletal problems that cannot be corrected without jaw surgery. Surgery may include procedures to lengthen or shorten the jaw (orthognathic surgery) and wires, plates or screws may be used to stabilize the jawbone.
In some situations a child may have selected primary teeth removed so that permanent teeth will erupt into proper position. Certain dental appliances may be necessary to help facilitate this process. The decision to remove permanent teeth must be made with special care.
Questions for your doctor about malocclusion
Preparing questions in advance can help patients to have more meaningful discussions regarding their or their child’s treatment options. The following questions related to malocclusion may be helpful:
- What form of malocclusion do you suspect I have?
- What are my treatment options? What are the pros and cons?
- How long do you estimate my treatment will last?
- At what age should my child begin treatment?
- Will my/my child’s treatment be broken up into several phases?
- What foods should I avoid during treatment?
- Will I need other treatments in addition to my main treatment?
- What extra treatment difficulties do I face as an adult?
- How significant is improvement in my condition likely to be?
- Is there a chance that my treatment will fail?
- What risks do I face if I decide not to have treatment?