Occlusion defines the relationship between the maxillary (upper) and mandibular (lower) jaws and teeth.

Malocclusion is diagnosed and assessed according to the Angle’s classes. The situation between the first permanent molar teeth of upper and lower jaws is assessed (usually they get cut when the child reaches the age of 6).

  • Class I. The occlusion is normal and close to perfect.
  • Class II. The upper jaw is bigger than the lower jaw. The upper front teeth are inclined sideward, forward or inward. The overjet of teeth makes the lower jaw seem retracted and the chin seems small.
  • Class III. The upper jaw is set too deep, while the lower jaw is inclined forward too much. Therefore, the upper front teeth are behind the lower front teeth. It may be difficult to chew and the patient’s chin is protrusive.

Why is malocclusion formed?

The formation of malocclusion may be affected by heredity, genetics, inappropriate dental care, and other reasons.

The malocclusion may be formed because of the following reasons:

  • Poor care of milk-teeth,
  • Habit to suck something (e.g., thumb) in order to calm down formed in childhood; or the baby’s dummy is used too long
  • Irregular breathing, breathing through mouth (e.g., I case of frequent cold or respiratory diseases in childhood)
  • Untimely prosthesis in case of early loss or extraction of tooth/teeth. In such cases other teeth also change their position and the occlusion gets deformed.
  • Grinding of the teeth (bruxism) caused by stress, tension, etc. The teeth get worn and the occlusion gets deeper and worse.
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What are the consequences of malocclusion that is left untreated?

Although very few people have completely straight teeth and correct occlusion, it is a mistake to consider that correction of occlusion is unimportant or important only for aesthetics.

The malocclusion that is left untreated for a long time may lead to more serious consequences:

  • Unsatisfactory chewing function (it is difficult to open a mouth, to bite or to chew);
  • Faster tear and wear of teeth,
  • Incoherent or incompletely coherent speech;
  • Pain, gnawing or crunching of temporomandibular joint caused by constant load;
  • Pain of neck and nape, especially headaches, posture disorders.
  • Changed form of the face, facial asymmetry, unsatisfying smile, aesthetical appearance;
  • Bad emotional condition related to unsatisfying aesthetical appearance.

Treatment of malocclusion

In order to avoid complex procedures in the future, treatment of malocclusion or consultations of the doctor should not be procrastinated. The children should be brought for consultation when their first teeth are cut or at least when they are 7-10 years old.

The dentist and orthodontist take part in treatment of malocclusion. If necessary, oral and maxillofacial surgeon also gives consultation.

The treatment’s complexity, stages and duration depends on the inveteracy of the problem and whether the jaw’s joints are damaged.

Malocclusion may be treated by occlusal splints, braces, while inlays are used to restore height and form of teeth.

In more severe cases when the jaws’ joints are damaged by constant loads or when occlusion cannot be restored by traditional methods or they cannot be used because of maxillary peculiarities, the orthognathic surgery may be a way out. It is important to understand that surgical treatment is applied only when the result cannot be achieved by non-invasive methods.

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Types of malocclusion


SIGNS The upper teeth extend farther than lower teeth. The frequent cause is too small lower jaw. The front teeth may be protruded forward a lot.
FACIAL PROFILE The facial profile is usually convex. A face may be low, a chin may be small, and a fold between the chin and the lower lip may be deep.
BREATHING The oropharynx is usually narrowed, breathing as if through stuffy nose. The patients tend to snore.
CHEWING Satisfactory
JOINTS It is an often case that the patients, who have such an occlusion, try to mask the deficit of lower facial third and keep their lower jaw a little pushed forward. This causes damage to joints, the ligaments are overstrained with time. They become too loose and start to crunch.
OOTH WEAR The molar teeth are often more worn


SIGNS The lower front teeth contact with upper front teeth edge-to-edge or they cover the upper teeth in the front. The frequent cause is too big lower jaw, too small upper jaw or both.
FACIAL PROFILE Usually concave, protrusive chin and sunken upper lip.
BREATHING Satisfactory
CHEWING Aggravated if front teeth are not in contact.
JOINTS The joints are often crunching because of irregular position of the lower jaw.
TOOTH WEAR The molar teeth are worn more than the front teeth.


SIGNS Only molar teeth are in contact. The gap is left between the front teeth even when they are occluded. The frequent cause is irregular position of upper jaw or wrong direction of lower jaw’s growth. This malocclusion may develop for children, who are in bad habit to suck a thumb, and for children, whose mouth stays open for a long period of time because of worsened nasal breathing.
FACIAL PROFILE Usually convex, high facial profile. Lips are a little opened in the calm state. Efforts are needed to close them. The chin’s and lower lip’s muscles are hypertrophied.
BREATHING The oropharynx is usually narrowed, breathing as if through stuffy nose. The patients tend to snore.
CHEWING Only molar teeth are used for chewing. It is impossible to bite food off because front teeth do not occlude.
JOINTS The occlusion is not stable. Only molar teeth are used for chewing. Therefore mandibular joints may be traumatized.
TOOTH WEAR The molar teeth are often worn more, as they are the only teeth used for chewing.


SIGNS All the teeth are in contact, but the front teeth are too overjet. When occluded, the upper teeth may cover the lower teeth completely in some cases. Usually it is observed in overbite cases. The frequent cause is too small lower jaw.
FACIAL PROFILE Usually convex, low face, protrusive lips, a very deep fold between the lower lip and the chin.

The oropharynx is usually narrowed, breathing as if through stuffy nose. The patients tend to snore.


CHEWING Satisfactory
Stable occlusion, rare disorders of mandibular joint’s function.
TOOTH WEAR The molar teeth may get worn faster.


SIGNS The upper molar teeth are inclined inward more than the lower teeth. The frequent causes are too narrow upper jaw (genetically), loss of baby’s teeth, breathing through mouth since childhood.
FACIAL PROFILE No big impact on facial profile. However, it is often observed together with open bite that is associated with oblong and convex facial profile.

The oropharynx is usually narrowed and the patients tend to snore. Iit is characteristic for people, for whom it is difficult to breath freely and who keep their mouth a little opened the majority part of the day.


CHEWING Satisfactory
JOINTS Due to wear the jaw’s joints may start crunching or aching.

The molar teeth are often more worn because of irregular inclination and thus they are sensitive.


SIGNS The upper molar teeth are inclined outward or the lower molar teeth are inclined inward so that they overlap without any contact at the time of biting. The possible causes are intensive expansion of upper jaw using the orthodontic devices in childhood, genes (naturally narrow arc of lower teeth).
BREATHING Satisfactory
CHEWING Difficult when there is no contact between the teeth at all
JOINTS The jaw may be directed to the enforced position where it would be more comfortable to chew. Therefore, the jaw’s joints may start crunching or aching.
TOOTH WEAR The molar teeth do not get worn as they are not in contact.