Nomenclature

Occlusion and Malocclusion

Topics Available:

Normal Occlusion in Dogs and Cats
Classification of Malocclusion in Dogs
Malocclusion Management

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Abbeviations to be used in AVDC Case Logs are shown in (blue brackets)


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Normal Occlusion


Ideal occlusion can be described as perfect interdigitation of the upper and lower teeth. In the dog, the ideal tooth positions in the arches are defined by the occlusal, inter-arch and interdental relationships of the teeth of the archetypal dog (i.e. wolf). This ideal relationship with the mouth closed can be defined by the following:

     Maxillary incisor teeth are all positioned rostral to the corresponding mandibular incisor teeth.

     The crown cusps of the mandibular incisor teeth contact the cingulum of the maxillary incisor teeth.

     The mandibular canine tooth is inclined labially and bisects the interproximal (interdental) space between the opposing maxillary third incisor tooth and canine tooth.

     The maxillary premolar teeth do not contact the mandibular premolar teeth.

      The crown cusps of the mandibular premolar teeth are positioned lingual to the arch of the maxillary premolar teeth.

     The crown cusps of the mandibular premolar teeth bisect the interproximal (interdental) spaces rostral to the corresponding maxillary premolar teeth.

      The mesial crown cusp of the maxillary fourth premolar tooth is positioned lateral to the space between the mandibular fourth premolar tooth and the mandibular first molar tooth.

Normal Occlusion in a Dog:


 

Normal Occlusion in a Cat:

Normal occlusion in cats is similar to dogs.

      Maxillary incisor teeth are labial to the mandibular incisor teeth, with the incisal tips of the mandibular incisors contacting the cingula of the maxillary incisors or occluding just palatal to the maxillary incisors.

     Mandibular canine teeth fit equidistant in the diastema between the maxillary third incisor teeth and the maxillary canine teeth, touching neither.

     The incisor bite and canine interdigitation form the dental interlock.

     Each mandibular premolar tooth is positioned mesial to the corresponding maxillary premolar tooth.

     The maxillary second premolar tooth points in a space between the mandibular canine tooth and third premolar tooth.

     The subsequent teeth interdigitate, with the mandibular premolars and first molar being situated lingual to the maxillary teeth.

     The buccal surface of the mandibular first molar tooth occludes with the palatal surface of the maxillary fourth premolar tooth.

The maxillary first molar tooth is located distopalatal to the maxillary fourth premolar tooth.


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Malocclusion

Malocclusion (MAL) is any deviation from normal occlusion described above.

Malocclusion may be due to abnormal positioning of a tooth or teeth (dental malocclusion) or due to asymmetry or other deviation of bones that support the dentition (skeletal malocclusion).

The diagnosis for a patient with malocclusion is abbreviated as: MAL (malocclusion) 1 or 2 or 3 or 4 (= malocclusion class designation)/specific malocclusion abbreviation and tooth or teeth number(s).
Example: MAL1/CB/R202 for a dog with class 1 malocclusion and a rostral crossbite of the left maxillary second incisor.
If multiple teeth have the same malocclusion, include the tooth numbers with a comma in between e.g. MAL1/CB/R202,302


Dental Malocclusions:

Neutroclusion - Class 1 Malocclusion (MAL1):

A normal rostrocaudal relationship of the maxillary and mandibular dental arches with malposition of one or more individual teeth.

Distoversion(MAL1/DV) describes a tooth that is in its anatomically correct position in the dental arch but which is abnormally angled in a distal direction.

Mesioversion (MAL1/MV) describes a tooth that is in its anatomically correct position in the dental arch but which is abnormally angled in a mesial direction.

Linguoversion (MAL1/LV) describes a tooth that is in its anatomically correct position in the dental arch but which is abnormally angled in a lingual direction.

Palatoversion (MAL1/PV) describes a tooth that is in its anatomically correct position in the dental arch but which is abnormally angled in a palatal direction.

Labioversion (MAL1/LABV) describes an incisor or canine tooth that is in its anatomically correct position in the dental arch but which is abnormally angled in a labial direction.

Buccoversion (MAL1/BV) describes a premolar or molar tooth that is in its anatomically correct position in the dental arch but which is abnormally angled in a buccal direction.

Crossbite (CB) describes a malocclusion in which a mandibular tooth or teeth have a more buccal or labial position than the antagonist maxillary tooth. It can be classified as rostral or caudal:
In rostral crossbite (CB/R): One or more of the mandibular incisor teeth is labial to the opposing maxillary incisor teeth when the mouth is closed. Similar to posterior crossbite in human terminology.
In caudal crossbite (CB/C): One or more of the mandibular cheek teeth is buccal to the opposing maxillary cheek teeth when the mouth is closed. Similar to posterior crossbite in human terminology.

 

Skeletal Malocclusions:


Symmetrical Skeletal Malocclusions:

Mandibular Distoclusion - Class 2 Malocclusion (MAL2):

An abnormal rostrocaudal relationship between the dental arches in which the mandibular arch occludes caudal to its normal position relative to the maxillary arch. Example:




Mandibular mesioclusion - Class 3 Malocclusion: (MAL3)

An abnormal rostralcaudal relationship between the dental arches in which the mandibular arch occludes rostral to its normal position relative to the maxillary arch. Example:




Aymmetrical Skeletal Malocclusions:

Maxillomandibular Asymmetry - Class 4 Malocclusion: (MAL4)

Asymmetry in a rostrocaudal, side-to-side, or dorsoventral direction:

Maxillomandibular asymmetry in a rostrocaudal direction (MAL4/RC) occurs when mandibular mesioclusion or distoclusion is present on one side of the face while the contralateral side retains normal dental alignment.

Maxillomandibular asymmetry in a side-to-side direction (MAL4/STS) occurs when there is loss of the midline alignment of the maxilla and mandible.

Maxillomandibular asymmetry in a dorsoventral direction (MAL4/DV) results in an open bite, which is defined as an abnormal vertical space between opposing dental arches when the mouth is closed.

The expression "wry bite" is a layman term that has been used to describe a wide variety of unilateral occlusal abnormalities. Because "wry bite" is non-specific, its use is not recommended.



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Management of Malocclusion


Orthodontics is a specialty in dentistry and oral surgery that is concerned with the prevention, interception and correction of malocclusion.

Preventive orthodontics is concerned with the client’s education, the development of the dentition and maxillofacial structures, the diagnostic procedures undertaken to predict malocclusion and the therapeutic procedures instituted to prevent the onset of malocclusion. Preventive procedures are undertaken in anticipation of development of a problem. Examples of preventive procedures include:

• Client education about time tables on exfoliation of deciduous teeth and eruption of permanent teeth

• Fiberotomy (severing of gingival fibers around a permanent tooth to prevent its relapse after corrective orthodontics)

• Operculectomy (surgical removal of an operculum to enable eruption of a permanent tooth)

• Extraction of a tooth that could pose a risk to development of malocclusion

Interceptive orthodontics is concerned with the elimination of a developing or established malocclusion. Interceptive procedures are typically undertaken in the growing patient. Examples of interceptive procedures include:

• Crown reduction of a permanent tooth in malocclusion

• Extraction of a tooth in malocclusion

Corrective orthodontics is concerned with the correction of malocclusion without loss of the maloccluded tooth or part of its crown. This is accomplished by means of tooth movement. Examples of corrective procedures include:

• Surgical repositioning of a tooth

• Orthognathic surgery to treat skeletal malocclusion

• Passive movement of a tooth using an inclined plane

• Active movement of a tooth using an elastic chain


Treatment plan (TP): Written document that outlines the progression of therapy (advantages, disadvantages, costs, alternatives, outcome and duration of treatment)

Impression (IM): Detailed imprint of hard and/or soft tissues that is formed with specific types of impression materials

Full-mouth impression (IM/F): Imprints of the dentition and/or surrounding soft tissues of the upper and lower dental arches

Diagnostic cast (DC): Positive replica created by pouring a liquid material into an impression or placing an impression into a liquid material; once the material has hardened, the cast is removed and used for the purpose of study and treatment planning; also called die (DC/D) when made from an impression of a particular tooth/area of interest or stone model (DC/SM) when made from a full-mouth impression

Bite registration (BR): Impression used to record a patient’s occlusion, which is then used to articulate diagnostic casts

Fiberotomy (FT): Severing gingival fibers around a permanent tooth to prevent its relapse after corrective orthodontics

Operculectomy (OP): Surgical removal of an operculum to enable eruption of a permanent tooth

Surgical repositioning (SR): Repositioning of a developmentally displaced tooth

Orthognathic surgery (OS): Surgical procedure to alter relationships of dental arches typically performed to correct skeletal malocclusion

Bracket/button/hook (OA/BKT): Device made of metal or plastic that is bonded to the tooth surface and aids in the attachment of wires or elastics; use OA/CMB if custom-made

Elastic chain/tube/thread (OA/EC): Orthodontic elastics used to move teeth

Orthodontic wire (OA/WIR): Metal wire with ‘memory’ used to move teeth

Arch bar (OA/AR): Device attached to one dental arch to move individual teeth in between the device’s attachments

Orthodontic appliance (OA): Device attached to a tooth or teeth to move a tooth or teeth

Orthodontic appliance adjustment (OA/A): Abbreviation used at the time of adjustment of the orthodontic appliance

Orthodontic appliance installation (OA/I): Abbreviation used at the time of installation of the orthodontic appliance

Orthodontic appliance removal (OA/R): Abbreviation used at the time of removal of the orthodontic appliance

Orthodontic counseling (OC): Client communication on the genetic basis, diagnosis and treatment of malocclusion and the legal and ethical implications of orthodontics

Ball therapy (BTH): Removable orthodontic device in the form of a ball or cone-shaped rubber toy (for example to passively move linguoverted mandibular canine teeth)

Inclined plane (IP): Fixed orthodontic device made of acrylic (IP/A), composite (IP/C) or metal (IP/M) with sloping planes (for example to passively move linguoverted mandibular canine teeth)

Orthodontic recheck (OR): Examination of a patient treated with an orthodontic appliance.