Physiological occlusion

Anomalies of individual tooth positions

Any deviation from the physiological norm often begins with improper eruption or displacement of a specific tooth. Such local defects can disrupt occlusion in a localized segment.

• Distal displacement. Characterized by the distal displacement of the tooth crown (from the median line) relative to its normal anatomical position. For example, when the permanent maxillary lateral incisor (tooth 12 according to the WHO classification) is displaced, natural proximal contacts with adjacent teeth are disrupted.
• Infraposition. Represents an anomaly in the vertical plane. In this pathology, a tooth (e.g., the upper right first molar — tooth 16) does not reach the general occlusal plane. Its chewing surface is located above the level of adjacent maxillary teeth, leading to a lack of contact with antagonist teeth.
• Tortoanomaly. Pathological rotation of a tooth around its longitudinal axis.
• Dystopia. A local disorder in which a tooth (often the maxillary canine) erupts outside the correct dental arch. With palatal positioning or blocking, such a tooth is completely excluded from normal occlusion.

Classification of anomalies in the lateral segment

Pathological dental closure in the lateral segment is classified according to three main planes:

1. Sagittal plane (anteroposterior direction):
2. Distal occlusion: the upper dental arch is displaced anteriorly relative to the lower, or the lower dental arch is displaced posteriorly relative to the upper.
3. Mesial occlusion: the reverse situation, where the upper arch is displaced posteriorly and the lower one anteriorly.

1. Vertical plane:
2. Dysocclusion: manifests as a pronounced gap between the dental arches when the jaws are closed. Due to the absence of fissure-cusp contacts between premolars and molars, chewing function is significantly impaired.

1. Transversal plane (lateral direction):
2. Vestibulocclusion: displacement of the dental arch towards the vestibule of the oral cavity (vestibulum oris) — labially or buccally. In this case, the teeth may overlap antagonists from the outside, blocking normal contacts.
3. Palatal occlusion: the upper posterior teeth are displaced or tilted towards the palate (palatally), forming a type of crossbite.
4. Linguocclusion: displacement of the mandibular teeth towards the tongue (lingually).

Occlusion anomalies in the anterior segment

The anterior segment of the dental arch is also prone to specific disorders that prevent the formation of a normal bite.

Sagittal pathologies:

• Sagittal incisor dysocclusion: the presence of a pronounced gap (sagittal gap) between the upper and lower incisors in the anteroposterior direction.
• Reverse incisor occlusion (anterior crossbite): the lower incisors are located vestibularly (anteriorly) relative to the upper ones, overlapping them, which is strictly opposite to the norm.
• Reverse incisor dysocclusion.

Vertical pathologies:

• Deep incisor occlusion.
• Deep incisor dysocclusion: excessive vertical overlapping of the lower incisors by the upper ones, with a complete absence of incisal-cusp contact.
• Vertical incisor dysocclusion and straight incisor occlusion.

Transversal pathologies:

• Include anterior cross occlusion and anterior cross dysocclusion.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Formation of the sagittal gap in dysocclusion.
• Effect of vestibulocclusion on fissure-cusp contacts.
• Impairment of chewing function in lateral dysocclusion.
• Features of local dental arch defects in canine dystopia.

Other topics in "Chapter 11. Introduction to Orthodontics"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.