Etiology of malocclusion

‫الرحيم‬‫الرحمن‬‫هللا‬‫بسم‬
Ibn Sina University
Faculty of Dentistry
Department of Orthodontics
Etiology of
Malocclusion
Mohanad H. Elsherif
BDS (U of K), MFD RCSI, MFDS RCPS(Glasg), MSc (Orthodontics), M.Orth RCSEd

Why study etiology?
 Elimination of the
etiology is the first
step in treatment
 Persistence of the
etiology is one of the
major causes of post-
treatment relapse

What causes malocclusion?
 Interaction of genetic and environmental
factors.
 Although it is difficult to know the
precise cause of most malocclusions, we do
know in general what the possibilities are,
and these must be considered when
orthodontic problems are being evaluated.

Etiology of malocclusion
 Can be classified into:
 General factors
 Local factors
Or
 Skeletal factors
 Soft tissue factors
 Local or dental factors
 Habits

 General factors:
1. Hereditary.
2. Congenital.
3. Environmental.
4. Predisposing metabolic, climate or disease.
5. Dietary problems.
6. Habits.
7. Posture
8. Trauma and accident.

Etiology of malocclusion/General
factors
1.Heriditary
 The child is a product of parents who have dissimilar genetic
make up.
 Thus the child may inherit conflicting trait from both parents
resulting in dentofacial deformity.
 Some features are thought to be inherited such as:
 Toot size.
 Arch dimension.
 Overjet.
 Abnormality in teeth number.

factors
2.Congenital
 These are malformation seen at the time of birth.
 Can results from several factors including chemicals, radiation,
infections.
 Example: cleft lip and palate

factors
3. Environmental
 Can be classified into:
 Prenatal factors:
 Abnormal fetal posture
 Maternal diet
 Maternal illness (German measles, teratogenic drugs)
 Post natal factors
 Forceps delivery
 Cerebral palsy
 Childhood trauma

factors
4. Predisposing metabolic, climate or disease.
 Endocrine imbalance
 Metabolic disturbances
Infectious disease
5. Dietary problems (e.g. nutritional deficiency).
6. Habits.
7. Posture
8. Trauma and accident.

 Local factors:
1. Abnormalities of tooth
number.
size.
shape.
4. Abnormal frenal
attachment.
5. Premature loss of
deciduous tooth.
6. Prolonged retention of
deciduous tooth.
7. Delayed eruption of
permanent teeth.
8. Abnormal eruptive path.
9. Ankyloses.
10. Dental caries.
11. Improper restoration.

Etiology of malocclusion/
Local factors
a. Abnormality in tooth number
1. Hypodontia (missing Teeth):
 Prevalence:
 0.1-0.9% in primary dentition.
 4-6% in permanent dentition (excluding third molars).
 25-35% of all third molars are missing.
 The permanent teeth most likely to be congenitally missing are the mandibular
second premolars and the maxillary lateral incisors.
 Female > Male = 3:2.
 Maxillary central and lateral incisors are the teeth most likely to be lost to trauma.

Etiology of malocclusion/Local
factors: abnormalities in number
 Types of hypodontia:
a. Hypodontia: congenital absence of 1 - 6 teeth.
b. Oleigodontia: congenital absence of more than 6 teeth.
c. Anodontia: congenital absence of all teeth.
 Syndrome associated with hypodontia:
 Ectodermal dysplasia.
 Down syndrome.
 Cleft lip and palate.

Etiology of malocclusion/local
factors: abnormalities in number
2. Supernumerary Teeth:
 Presence of extra tooth or teeth.
 Also called hyperdontia.
Prevalence:
 0.8% in primary dentition
 2% in permanent dentition.
 Males>Females = 2:1
 90% of all supernumerary teeth are found in the anterior
part of the maxilla.

Etiology of malocclusion/Supernumerary
teeth
 Associated syndromes
A. Cleidocranial dysplasia
B. Gardner syndrome.
C. cleft lip and palate

Types of supernumerary:
1. According to the position:
A. Mesiodense:
 Most common type of
supernumerary teeth.
 Conical in shape and Found
in the midline.

B. Paramolar:
 Buccal and palatal to premolar and molar.

C. Distomolar:
Found distal to the last molar tooth

2. According to the shape
A. Conical

Etiology of
malocclusion
2. According to the shape
B. Tuberculate:
 These are barrels in shape.
 They usually have no roots
thus most of them do not
erupt.
 The most common cause of
maxillary incisors impaction is
tuberculate supernumerary.

Etiology of
malocclusion
1. according to the shape
C. Supplemental
Resemble the normal teeth
shape and usually occurs at
the end of the series.

1. according to the shape
D. Odontomas:
 They are the most common odontogenic tumors and they usually interfere
with eruption of permanent teeth.
 They are usually asymptomatic and are discovered during routine radiographic
examination when there is delayed eruption of permanent tooth.
 Usually are two types:
 Compound odontoma.
 Complex odontoma.

D. Odontomas:
a. Compound odontoma:
 It is a collection of small
radiopaque masses, some or
all may be tooth-like
structures “denticles”.
 62% in the anterior region
of the maxilla and usually
associated with the crown of
an unerupted canine.

D. Odontomas:
b. Complex odontoma:
 It is composed of
haphazardly arranged dental
hard and soft tissue.
 It has no resemblance to a
normal tooth.
 It tends to occur in 70% in
the posterior region of the
mandible.

Effects of supernumeraries:
 Midline diastema.
 Crowding.
 Labial or palatal deflection of teeth.
 Impaction of permanent teeth.
 No effect.

Etiology of malocclusion/ local
factors
b. Abnormalities of tooth size
a. Macrodontia:
 Teeth larger than normal
 Types:
 True generalized macrodontia: all teeth are
larger than normal e.g. in pituitary gigantism.
 Relative generalized macrodontia: normal or
slightly normal teeth present in jaws that are
smaller than normal.
 Localized macrodontia: usually one tooth is
involved, mostly affects maxillary central
incisors.

Etiology of malocclusion/
local factors
b. Abnormalities of tooth size
a. Microdontia:
 Teeth smaller than normal
 Types:
 True generalized microdontia: all teeth are
smaller than normal e.g. in pituitary dwarfism.
 Relative generalized microdontia: normal or
slightly normal teeth present in jaws that are
larger than normal.
 Localized microdontia: usually one tooth is
involved, mostly affects maxillary lateral
incisors (peg lateral) and third molars.

factors
c. Abnormalities of tooth shape
 Double teeth
 Gemination
 Fusion

factors
 Concrescence
Fusion by cementum

factors
c. Abnormalities of tooth
shape
 Accessory cusps
Example:
Talon cusp: palatal to lateral
incisors

factors
 Dense in dente (tooth in tooth)

factors
 Taurodontism

factors
c. Abnormalities of tooth
shape
 Dilaceration:
 Bending in the root
 Can be idiopathic or due to
trauma

factors
d. Premature loss of deciduous tooth:
 Can be due to caries, trauma or less commonly periodontal disease
 Effects of early loss of primary teeth:
1. Primary Incisors:
 Minimal effect after eruption of deciduous canines.
 No space maintainer is usually needed except for aesthetic or speech.
2. Primary Canines:
 Can cause midline shift.
 Space maintainer or balanced extraction of the contralateral canine is
indicated.

factors
3. Primary first molar:
 Can cause midline shift specially if it was lost in young age.
 Space maintainer is indicated.
4. Primary second molar:
 Can space loss by mesial drift of the first molar can occur.
 Space maintainer is indicated.

factors
e. Prolonged retention of primary tooth
 Reasons:
 Absence of permanent teeth
 Endocrine disturbance such as hypothyroidism
 Ankylosed primary tooth that failed to resorption

Etiology of malocclusion/ Local
factors
f. Delayed eruption of permanent teeth:
 Reasons
 Missing permanent teeth.
 Lack of space.
 Retained deciduous or premature loss of deciduous tooth.
 Presence of physical barrier ( heavy mucosa, supernumerary, tumor, cyst).
 Primary failure of eruption
 Endocrine disturbance (hypothyroidism)

factors
g. Ankyloses
A condition where part or the whole root surface is directly
fused to the bone with absence of intervening periodontal
ligament.
 Causes
 Trauma
 Infections
 Endocrine disturbance

factors
h. Abnormal frenal attachment

factors
i. Caries and improper restoration

Declaration
 The author wish to declare that; these presentations are his original work, all
materials and pictures collection, typing and slide design has been done by the
author.
 Most of these materials has been done for undergraduate students, although
postgraduate students may find some useful basic and advanced information.
 The universities title at the front page indicate where the lecture was first
presented. The author was working as a lecturer of orthodontics at Ibn Sina
University, Sudan International University, and as a Master student in Orthodontics at
University of Khartoum.
 The author declare that all materials and photos in these presentations has been
collected from different textbooks, papers and online websites. These pictures are
presented here for education and demonstration purposes only. The author are not
attempting to plagiarize or reproduced unauthorized material, and the intellectual
properties of these photos belong to their original authors.

Declaration
 As the authors reviews several textbooks, papers and other references during
preparation of these materials, it was impossible to cite every textbook and journal
article, the main textbooks that has been reviewed during preparation of these
presentations were:
Contemporary Orthodontics 5th edition; Proffit, William R, Henry W. Fields, and
David M. Sarver.
Handbook of Orthodontics. 1st edition; Cobourne, Martyn T, and Andrew T. DiBiase.
Essentials of orthodontics: Diagnosis and Treatment; Robert N. Staley, Neil T. Reske
Orthodontics: Current Principles & Techniques 5th edition; Graber, Lee W, Robert L.
Vanarsdall, and Katherine W. L. Vig
Orthodontics: The Art and Science. 3rd Edition. Bhalajhi, S.I.

Declaration
 For the purposes of dissemination and sharing of knowledge, these
lectures were given to several colleagues and students. It were also
uploaded to SlideShare website by the author. Colleagues and students
may download, use, and modify these materials as they see fit for non-
profit purposes. The author retain the copyright of the original work.
 The author wish to thank his family, teachers, colleagues and students
for their love and support throughout his career. I also wish to express
my sincere gratitude to all orthodontic pillars for their tremendous
contribution to our specialty.
 Finally, the author welcome any advices and enquires through his
email address: Mohanad-07@hotmail.com

Etiology of malocclusion

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