Definitions:
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Crowding:
Disharmony between the sizes of teeth and space available in the alveolus.
Usually occurs as a result of as a result of disproportions between tooth size and arch length.
Relative decrease in arch length/increase in tooth material may result in crowding.
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Displacement:
Movement of whole bone as a unit.
Primary: displaced as a result of its own growth.
Growth of maxilla at tuberosity area – maxilla pushes against cranial base = forward and downward displacement of maxilla
itself.
Secondary: displaced as a result of its own growth and enlargement of adjacent bone.
Growth of cranial base = forward and downward displacement of maxilla.
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Rotation:
Tooth movements which occur around their long axes.
2 types
o Mesio-Lingual/Disto-buccal
o Disto-lingual/Mesio-buccal
 Anterior rotated teeth occupy less space, thus when derotated, will require additional space.
 Posterior rotated teeth occupy more space, thus when derotated, space is gained.
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Spacing
Teeth spacing is characterized by interdental spaces and lack of contact points between teeth.
Localized = 2/4 teeth involved
Generalized if both anterior and posterior teeth are involved – entire arch involvement.
In primary dentition it is a positive prognostic sign.
In secondary dentition it is abnormal.
Often as a manifestation of Class I malocclusion.
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Transportation
Tooth in the incorrect anatomical position when it erupts.
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Embedded/Impacted teeth
Impacted teeth fail to erupt fully into the oral cavity within the expected time
Due to impact with the jaw bone, adjacent tooth or even the gums.
Main reason: Lack of an adequate dental arch length and space in which to erupt into.
Studies have shown the mandibular last molar to be the most commonly impacted tooth
Followed by the maxillary third molars, the maxillary canines and the mandibular premolars.
Impacted teeth predispose to periodontal disease and dental caries of adjacent teeth
Resulting in pain, discomfort and loss of function.
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Ectopic eruption
Disturbance in which tooth does not follow its normal eruptive pathway
4 possible causes:
1) Small arches.
2) Deviant paths of eruption of the permanent molar.
3) Lack of forward movement of all primary teeth, and
4) Early eruption of the maxillary first permanent molars.[2]
 Sweet classified ectopic eruption on the following basis:
a) Eruption of mandibular permanent lateral incisors initiating loss of the primary canines.
b) Eruption of the maxillary first permanent molar initiating loss of the second primary molar.
c) Eruption of the maxillary permanent lateral incisor initiating loss of the primary canine.
d) Eruption of the mandibular first permanent molar initiating loss of primary second molar.
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Ankylosed teeth
Condition wherein part/whole of tooth root cementum surface is directly fused to bone
With absence of intervening periodontal membrane
Usually bc of trauma to tooth perforating the periodontal fibres/associated with infections/endocrinal disorders/disturbed
local metabolism/chemical or thermal disruption/cleidocranial dysostosis – other congenital disorders.
 Clinically = submerged teeth (fail to erupt to normal level)
 Possibly totally submerged in alveolar, thus adjacent teeth migrate to space.
 Tooth is immobile to manual rocking.
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Malformed teeth
10. Dilaceration of roots
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Condition characterized by abnormal angulation between crown and root of tooth
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Or by angulation within a root
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Usually related to a blow to the primary tooth, transmitted to the underlying permanent tooth bud.
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Dilacerated teeth fail to erupt to normal level, can cause malocclusion.
Anomalies in tooth number:
11. Supernumerary teeth:
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Teeth which are “extra” to the normal complement of teeth.
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They also have abnormal morphology – not resembling normal teeth.
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If extra teeth resemble normal teeth = “supplemental teeth”.
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75% of supernumerary teeth remain impacted in bone, only radiographically diagnosed.
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More common in permanent dentition than deciduous.
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Usually occurring majority in anterior palate.
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2: 1 Males: Females
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Multiple supernumeraries noted in Cleidocranial Dysplasia, oral-facial-digital syndrome type 1, Gardner syndrome.
12. Congenitally absent teeth:
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Far more common than supernumerary, occurring in maxilla/mandible.
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Referred to hypodontia if a few teeth missing from arch.
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Referred to anodontia if all teeth are absent.
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If total of 6+ teeth absent = oligodontia.
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In order of frequency of teeth absent: 8’s, Mx 2’s, Md 5’s, Md 1’s or 2’s, Mx 5’s.
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More prevalent in permanent dentition than deciduous dentition.
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Unilateral or bilateral occurrence.
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May occur along with other anomalies like additional teeth.
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Predisposition to spacing in dental arch.
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Migration of adjacent teeth = axial inclination of teeth.
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Absence of permanent teeth often results in over-retained deciduous teeth.
Anomalies in tooth shape
13. Microdontia:
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Teeth which appear smaller in size than normal.
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Generalized is rare; usually associated with hypopituitarism, radiation exposure/chemotherapy during dental
development.
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Possible predisposition to spacing.
14. Macrodontia:
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Any tooth/teeth which are abnormally large than particular tooth of that type.
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Rarely involves the whole dentition and may be generalized in pituitary gigantism/individuals with small jaw.
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May result in crowding.
15. Fusion:
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Union between dentine and/or enamel of two or more separate in developing teeth.
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Usually leads to a reduced number of teeth in an arch.
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Sometimes a supernumerary tooth and normal tooth are fused.
16. Gemination:
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Two teeth partially develop, from a single tooth bud, following incomplete division.
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Usually only one root canal present.
17. Concrescence:
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Roots of one or mote teeth united by cementum only – after the formation of crowns.