Transcript of "Etiology of malocclusion local factors /certified fixed orthodontic courses by Indian dental academy "
INDIAN DENTAL ACADEMY
Leader in continuing dental education
Anomalies of number
a) Supernumerary teeth.
b) Missing teeth (congenital absence or loss
due to trauma,caries,etc.)
2. Anomalies of tooth size.
3. Anomalies of tooth shape.
4. Abnormal labial frenum.
1) Anomalies of number
A) Supernumerary teeth:
Supernumerary teeth is a teeth, which is various in
size , shape and location when compared to the normal
B)Supplemental teeth :
Supplemental teeth is a teeth ,which is closely
resembles the particular group of teeth.
This is most commonly seen in premolar region
and lateral incisor region.
Supernumerary teeth result from disturbances
during the initiation and proliferation stages of
Supernumerary teeth occur most commonly
in the maxilla..
The most commonly seen supernumerary
teeth is mesiodens.
Mesiodens is a small tooth with a cone
shaped crown and short root.
It is seen between the two maxillary central
The presence of teeth obviously has great
potential to disturb normal occlusal development.
The frequency of other supernumerary teeth are
paramolars and distomolars.
Multiple supernumerary teeth are seen in
Cleidocranial dysplasia is characterized by
- Abnormalities of skull,teeth,jaws and
-The defect of shoulder girdle ranges from
complete absence of clavicle to partial
- Multiple unerupted supernumerary teeth is
also present in this condition.
B)Congenitally Missing Teeth
Congenital absence of teeth results from
disturbances during the intial stages of tooth
Anodontia – Total absence of teeth
Oligodontia - Absence of many but not all the
Oligodontia showed a tendency for
delayed tooth formation*.
(* Angle orthodontist vol 63 No:1,1993).
Ectodermal dysplasia is characterized by
soft , smooth , thin and dry skin with partial
or complete absence of sweat glands.
The sebaceous glands and hair follicles are
The bridge of the nose are depressed.
This also manifested with anodontia or
Frequency of absence(Missing)
Maxillary and Mandibular third molars
Maxillary lateral incisors
Mandibular second premolar
Maxillary second premolar
Congenitally missing teeth can lead to
spacing between teeth and aberrant
2)Anomalies of Tooth Size :
A tooth size is determined by heredity .
Anomalies of Tooth Size
True generalized microdontia is usually
associated with pituitary dwarfism.
True generalized macrodontia is usually
associated with pituitary gigantism.
The most commonly localized microdontia
involves the maxillary lateral incisors (peglaterals).
3)Anomalies of Tooth Shape :
Intimately related to tooth size is tooth shape.
Abnormal shaped teeth predispose to
Presence of maxillary-‘Peg lateral’ incisors
spacing will often occur in the maxillary anterior
Abnormally large cingulum on the
maxillary incisor (Talons cusp) or heavy
marginal ridge can force the teeth labially and
prevent the establishment of a normal
Mandibular second premolar also shows
great variation in shape & size. It may have
an extra lingual cusp , which usually serve to
increase the mesiodistal dimension of the
Anomalies of shape can also occur as a result of
dens in dente,
congenital syphilitic aberration such as
Hutchinson‘s incisors and mulberry molars.
Dilaceration is a condition characterized by
an abnormal angulation between the crown
and root of a tooth .Dilacerated teeth fails
to erupt to normal level and can cause
4) Abnormal Labial Frenum :
Abnormalities of the maxillary labial frenum are
associated with a midline diastema .
At birth frenum is attached to the alveolar ridge
with fibers running into the incisive papilla. The teeth
erupts and as alveolar bone is deposited, the frenum
attachment migrates superiorly with the alveolar ridge.
Fibers may persist between the maxillary central
incisors and in the ‘V’ shaped intermaxillary suture ,
attaching to the outer layer of the periosteum and
connective tissue of the suture.
Faust in Weber ,noted that diastema may be due to
other factors, the possible causative factors :
Microdontia, Macrognathia,Super numerary teeth,Peg
laterals,Missing lateral incisors ,Habits as thumb
sucking, tongue thrusting & midline pathologies.
Diastema Due to Abnormal Frenum
5)Premature loss of Deciduous teeth :
Deciduous teeth are the space savers for the
They also maintaining the opposing teeth at the
proper occlusal level.
Deciduous cuspids are frequently shed
pre-maturely and nature provide more space to
align the permanent incisor teeth that have already
Pre mature removal of posterior deciduous
teeth because of caries Malocclusion unless
space maintainers are placed.
Lee way Space :
In the mandibular arch combined width of the
deciduous canine, First & second deciduous molar is
on the average of 1.7 mm greater on each side than the
In the maxillary arch “lee way space” average is
0.9mm because of the greater size of the permanent
canine, first and second pre molar teeth.
This space differential is necessary for the occlusal
adjustment and final alignment of the incisors.
Pre mature loss (Extraction) of the deciduous
second molar will lead to mesial drift of the first
permanent molar and blocking of the erupting
The early loss of permanent teeth should be
considered just as severe a ‘Malocclusion maker’
as loss of deciduous teeth.
6)Prolonged retention of deciduous teeth :
Whatever the reason for the prolonged retention of
deciduous teeth, they have a significant impact on the
Whichever deciduous teeth may be retained beyond
the usual eruption age of their permanent successor is
capable of causing buccal / labial or Palatal / Lingual
Impacted in the maxillary arch might lead to the
permanent tooth erupting is a cross bite,which might be
difficult to treat at a later stage.
Impacted Permanent teeth are more difficult to
correct orthodontically, by surgical exposure most
commonly impacted tooth is the maxillary canine(3rd
molars not in consideration) the reason
It’s the last anterior tooth to erupt.
Space occupied by the deciduous canine is lesser
than the mesiodistal width of the permanent canines.
It has longer path of eruption
7 )Delayed eruption of permanent teeth:
1.Early loss of adjacent primary teeth with a
consequential flaring or spacing between erupted teeth
may lead to decreased space availability for eruption of
the succedaneous teeth.
2. Early loss of primary tooth leading to mucosal
thickening over the succedaneous tooth .
3. Early loss of the primary tooth might cause excessive
bone deposition over the succedaneous tooth.
4. Due to hereditary in certain children teeth erupt
much later than established norms.
5.Presence of supernumerary tooth can block the
erupting permanent tooth.
6. Presence of odontomas or other cysts and tumors
might prevent the permanent tooth from erupting.
7. Presence of deciduous root fragment that are not
resorbed can block these erupting tooth or may deflect it
preventing its eruption in an ideal location.
8. Presence of ankylosed deciduous teeth,these might not
get resorbed causing a delay in the eruption of the
9. The succedaneous tooth might be congenitally
missing delaying the loss of the primary tooth.
10. In certain endocrine disorders the eruption of
permanent teeth might be delayed.
8)Abnormal Eruptive path :
1.Tooth bud facing and/or placed or displaced from its
2.Presence of a supernumerary tooth may divert a tooth
from its eruptive path.
3. Presence of odontomas or a cyst tumour may divert
it if not altogether prevent its eruption.
Abnormal Eruptive path(cont..)
4. Un resorbed or retained deciduous teeth might
force a tooth to erupt along a path of least resistance
rather than in place of the deciduous tooth.
5. Retained root fragments may deflect an erupting
6.Arch length deficiencies or excess of tooth material
may cause one or more teeth to deviate from their
Ectopic Eruption :
Malposition of a permanent tooth bud can
lead to eruption in wrong place.This condition is
called ectopic eruption.
Most likely to occur in the eruption of
maxillary first molars.
Ecotopic eruption may generally be
considered a manifestation of arch length
Ankylosis is the condition which involves
the union of the root or part of a root directly to
the bone, without the intervening periodontal
Ankylosis or partial ankylosis is
encountered relatively frequently during the 6 to
12 year age period.
Ankylosis of teeth is more commonly
associated with certain infections, endocrine
disorders and congenital disorders.
Ex : Cleidocranial dysostosis , but there are
Ankylosis may be due to past history of
Dental caries which leads to the
premature loss of a deciduous or
permanent tooth subsequent drifting of
contiguous teeth ,abnormal axial
inclination,over eruption and bone loss.
11)Improper dental restorations :
Due to improper dental restoration under
contoured proximal restoration can lead to a
significant decrease in the arch length especially in the
Proper knowledge of preventive and
interceptive orthodontics can definitely reduce the
occurrence of malocclusion ,if not prevent them
Leader in continuing dental education