The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
00919248678078
2. INDIAN DENTAL ACADEMY
Leader in continuing dental
education
www.indiandentalacademy.com
www.indiandentalacademy.com
3. Introduction
Malocclusion may be defined as
a significant deviation from what is defined as
normal or ideal occlusion (Andrews,1972) *.
The term ‘normal occlusion' is arbitrary,
but is generally accepted to be class I molar
relationship with good alignment of all teeth *.
*(The heritability of malocclusion:part 2. P.A. Mossey, British journal of orthodontics/vol.
26/1999)
www.indiandentalacademy.com
12. Heredity
Genetically homogenous population tend to
have normal occlusion as the Melanesians
of the Philippine islands, in whom the
malocclusion is almost non-existent.
In heterogenous population , the incidence
of jaw discrepancies and occlusal
disharmonies is significantly greater.
www.indiandentalacademy.com
13. Role of homeobox genes
These genes are known to play a role in patterning the embryonic
development.
These are master genes of head and face controlling
patterning , induction, programmed cell death and epithelial
mesenchymal interactions.
Important genes in craniofacial development include Hox
group, Msx1 & Msx2, Dlx, Otx, Gsc and Shh.
Two major groups of regulatory proteins including
mesenchymal growth factors, BMPs and steroids/ thyroid/
retinoid group are the vehicles through which Hox genes
information is expressed.
(The heritability of malocclusion:part1; P.A. MOSSEY, British
Journal of orthodontics/vol.26/1999/103-113)
www.indiandentalacademy.com
14. Horowitz etal.(1960) studied fraternal and identical adult twin pairs
using only linear cephalometric measurements, and he demonstrated
highly significant hereditary variations in the anterior cranial base,
mandibular body length, lower face height, and total face height..
( P.A. Mossey, British journal of orthodontics, vol. 26/1999/195-203).
Primary sites affected by genetically
transferred dentofacial deformities
–
–
–
–
Neuromuscular system
Dentition
Bone & Cartilage
Soft Tissues (except muscles)
www.indiandentalacademy.com
15. Neuromuscular system
Consist anomalies in
– size, position, tonicity, contractility and
neuromuscular coordination pattern of
facial, oral & tongue musculature
www.indiandentalacademy.com
16. Lip deformities
The lower lip plays more
important role than the
upper lip in function
movements and in
governing the position of
lower incisors in normal
function during swallowing,
speech & smiling.
The inherited pattern of lips
can result in malocclusion.
Abnormalities in lip form
and lip line can cause
malocclusion.
www.indiandentalacademy.com
17. Tongue deformities
Tongue Size : Macroglossia
Microglossia
Tongues Positions
In case of
incompetent lips, tongue
protrudes between the teeth to
touch the lower lips. This
allows nasal breathing n
prevents full vertical
development of incisors
leading to open bite.
www.indiandentalacademy.com
18. Dentition
Heredity is the main cause of abnormality in dentition.Twin studies
have shown that tooth crown dimensions are strongly determined
by heredity (Osborne etal, 1958)*.
The molecular genetics of tooth morphogenesis with the
homeostatic Hox 7 and Hox 8 (now referred to as MSX1 and
MSX2) genes being responsible for stability in dental patterning is
confirmation of Butler’s field theory (1963)*.
(The heritability of malocclusion:part 2;P.A. Mossey, British Journal of Orthodontics/vol.26/
1999/195-203)
Abnormalities
–
–
–
–
Size, shape, number of teeth
Mineralization of teeth
Path of eruption in primary position of tooth germ
Sequence of eruption www.indiandentalacademy.com
21. Number
Hypodontia
MSX1 & PAX9 genes are found
to be involved in some families
with non-syndromic autosomal
dominant hypodontia .
1
Hyperodontia
Supernumary teeth,most frequently
seen in premaxillary region with male
sex predilection, are also genetically
determined
www.indiandentalacademy.com
2
22. Mineralisation
Inherited defects differ from exogenic
induced disturbances
– present in both deciduous & permanent
teeth
– localized in either enamel or dentin
– arranged irregularly or as vertical ridges
& grooves
www.indiandentalacademy.com
23. Bones & Cartilage
Bone morphology or growth alter occlusal relation &
functioning
Factors
–
–
–
–
Bone size
Shape of jaw bases
Bone location
Number of bones present
Inherited skeletal malocclusions
–
–
–
–
–
Class II, division 2
Mandibular Prognathism
Bimaxillay protrusion
Skeletal open bites
www.indiandentalacademy.com
Mandibular retrognathism
24.
…rotational growth of mandible resulted from the condylar
growth pattern and this would be under genetic control..*
…forwardly rotated mandible is largely responsible for
strong chin, hypodivergent angular relationship of mandible
with cranial base and deep, restrictive over bite.*
…atleast three hard-tissue anatomic features with
generally accepted hereditary bases: small tooth size,
abundant mandibular basal growth, strong chin.*
Inheritance of a complex occlusal variation in Angle’s class
II division 2 malocclussion may actually be polygenic and
additive in nature , through combined expression of
genetically determined anatomical components, rather than
being the effect of a single controlling gene for the entire
occlusal malformation.*
*(classII division 2 malocclusion: A heritable pattern of small teeth in welldeveloped jaws. Sheldon peck, Angle 0rthodontist vol.1;9-20;1998)
www.indiandentalacademy.com
26. Bone Location
Prognathism
– Mandibular prognathism and class
II division 2 are attributed to
dominant inheritance.
– Best known example of familial
mandibular prognathism is referred
to as the Hapsburg jaw.
Retrognathism
www.indiandentalacademy.com
29.
Achondroplasia
Autosomal dominant characterstics.
Failure of synchondrosis leads to
underdevelopment of midface because the upper
jaw is not translated forward by normal lengthening
of the cranial base.
This results in Class III malocclusion.
Pierre Robins syndrome
Triad of features are:
Glossoptosis
Cleft palate
Micrognathia
This results in Class II malocclusion.
www.indiandentalacademy.com
30.
Craniofacial dysostosis
Transmitted as autosomal dominant trait.
Premature craniosynostosis with or without
syndactyly.
Hypoplasia of maxilla with mandibular
prognathism and a high arched palate,
parrot’s beak nose
Treacher Collins syndrome
Hypoplasia of facial bones
Macrostomia, high palate, abnormal position of
teeth
Bird like or fish like facies.
www.indiandentalacademy.com
31.
Down syndrome
Features include:
- Macroglossia, fissured tongue, or pebbly
tongue.
- High arched palate.
- Enamel hypoplasia, microdontia.
- Severe periodontitis
Gardner’s syndrome
- Multiple impacted supernumerary teeth
- Multiple Polyposis of large intestine
- Osteoma of bones
- Multiple Epidermoid cysts
- Desmoid tumors
www.indiandentalacademy.com
32.
Marfan syndrome
–
–
–
–
Autosomal dominant trait
Defective organization of collagen.
Long and narrow face
Hyperextensibility of joints
High arched palatal vault
Multiple odontogenic cysts
Hereditary ectodermal dysplasia
X-linked recessive
– Hypohidrosis
– Hypotrichosis
– Hypodontia
www.indiandentalacademy.com
33. Cleidocranial dysostosis
Unilateral or bilateral , partial or
complete absence of clavicle.
Delayed closure of cranial suture,
maxillary retrusion, Mandibular
protrusion , retarded eruption of
permanent teeth, retained deciduous
teeth & supernumary teeth.
Mutations have been found in core
binding factor 1 gene(CBFA1).
www.indiandentalacademy.com
35. Congenital Deformities
Caused by developmental damage
during fetal period (Moss 1967, Enlow 1982)
–
–
–
–
Cleft lip & Palate
Cerebral palsy
Torticollis
Congenital syphilis
www.indiandentalacademy.com
36. Cleft lip & Palate
Most frequent congenital
deformity
Incidence 1:700 live births
Can be caused by the use of
teratogens like , aspirin, dilantin,
6-mercaptopurine, valium and
cigarette smoke.
In Unilateral cleft, teeth on the
affected site are in lingual cross
bite
Teeth are frequently crowded in
cleft
www.indiandentalacademy.com
38. Cerebral palsy
Paralysis or lack of muscular
coordination attributed to intracranial
lesion
Commonly result of birth injury
Lack of motor control causes
abnormal function in mastication
,deglutition ,respiration & speech.
Thus affects normal occlusion .
www.indiandentalacademy.com
39. Torticollis or Wry neck
Malocclusion &
alteration in
morphology of
cranium & face is
caused due to
foreshortening of
sternomastoid muscle.
www.indiandentalacademy.com
41. Environment
Phenotypes are products of genotypes
and the ultimate product is blend of
inheritance potential as it has been
modified by a dynamic environment.
Prenatal influence
Postnatal influence
www.indiandentalacademy.com
42. Prenatal influence
Uterine posture , fibroids of mother ,
amniotic lesions
German measles , maternal diet ,
metabolism , drug like thalidomide
induced deformities
www.indiandentalacademy.com
43.
‘ Vogelgesicht’ ,
inhibited growth of
mandible due to
ankylosis of TMJ
Intrauterine pressure
or trauma cause
hypoplasia of
mandible
www.indiandentalacademy.com
44. Postnatal influence
Forceps delivery can injure
the TMJ
Disabling accidents
produces malocclusion
Milwaukee braces wear
produces malocclusion
– Maxillary incisors are tipped
labially
– Mandibular incisors fit into
deep palatal grooves
www.indiandentalacademy.com
45. Predisposing metabolic
climate & disease
Exanthematous fever
disturbs developmental
time table and often
leave permanent
marks on surfaces of
teeth.
Endocrine disorders
Infectious diseases
www.indiandentalacademy.com
46. Endocrine disorders
Prenatally , manifest as hypoplasia of
teeth.
Postnatally , retard or hasten , but do
not disrupt the direction of facial
growth. May affect the rate of
ossification of bone , eruption of teeth
& resorption of primary teeth.
www.indiandentalacademy.com
47. Hyperpituitarism
Hypopituitarism
Accelerated development of mandible
Accelerated development & eruption
Enlarged tongue and facial structure
Hypercementosis
Retarded growth
Decreased linear facial measurement
Decreased cranial base measurement
Open bite
Delayed tooth eruption
Incomplete root formation
www.indiandentalacademy.com
48. Hyperthyroidism
Hypothyroidism
Heat intolerance
Accelerated skeletal growth
Increased vertical face height
Open bite
Mild prognathism
Growth retardation
Decreased vertical growth of face
Decreased cranial base length
Anterior open bite
Delayed eruption
Maxillary protrusion
Spacing between teeth
www.indiandentalacademy.com
50. Infectious diseases
Nasopharyngeal diseases & impeded nasal
breathing.
Enlarged adenoids causes
–
–
–
–
–
Increased anterior facial height
narrow and high palate
Retroclined incisors
Increased lower facial height
Open bite & cross bite
Gingival and periodontal diseases
– Causes loss of teeth
www.indiandentalacademy.com
– Ankylosis of teeth
51. Nutritional deficiency
Malocclusion caused by
disturbed developmental time
table in :
- Rickets – Vit. D deficiency
- Scurvy – Vit. C deficiency
- Beri beri – Vit. B1 deficiency
Malocclusion is caused due
to
– Premature loss of teeth
– Prolonged retention
www.indiandentalacademy.com
– Poor tissue health
1
2
52. Protein deficiency
Delayed eruption
Decreased radicular
osteocementum
Vitamin A deficiency Calcification of
teeth is affected
Retarded eruption
General growth is slow
www.indiandentalacademy.com
53. Vitamin C deficiency
Disturbed collagen
formation
Bleeding gums
Loosening of teeth
Atrophy and
disorganisation of odontoblasts
Vitamin D deficiency
Hypophosphatemia
Disturbed calcification
www.indiandentalacademy.com
54. Abnormal pressure
habits
Habits are learned patterns of
muscle contraction.
–
–
–
–
Thumb & digit sucking
Tongue thrusting
Lip biting & sucking
Nail biting
www.indiandentalacademy.com
55. Thumb and digit sucking
Habit is considered normal till 3 ½ to 4
years of age.
Triad of factors
–
–
–
Duration of habit
Frequency of habit
Intensity of habit
www.indiandentalacademy.com
56. Thumb and digit sucking
Effects of thumb sucking
– Proclination of maxillary
anteriors
– Increased overjet
– Lingual tipping of
Mandibular incisors
– Anterior open bite
– Narrow maxillary arch
– Upper lip is hypotonic
– Hyperactive mentalis
www.indiandentalacademy.com
activity
57. Tongue thrusting
Condition in which tongue
makes contact with any
teeth anterior to molars
during swallowing.
Effects :
–
–
–
–
Proclination of anterior teeth
Anterior open bite
Bimaxillary protrusion
Posterior open bite in case of
lateral thrust
www.indiandentalacademy.com
– Posterior cross bite
58. Lip biting & sucking
Lower lip is turned inward and
pressure s exerted on lingual
surfaces of maxillary anterior
teeth .
Effects :
–
–
–
–
Proclined maxillary anteriors
Retroclined mandibular anteriors
Hypertonic lower lip
Cracking of lips
Nail biting
Causes minor local tooth
www.indiandentalacademy.com
irregularity
59. Posture
Stoop shouldered child with head hung so
that the chin rests on chest may have
mandibular retrusion.
Child resting his head on his hands or
sleeping on his arms , fists can have
malocclusion
Poor posture accentuates an existent
malocclusion
www.indiandentalacademy.com
60. Trauma or accidents
Idiopathic eruptive
abnormalities can be
caused due to the
blows on face and
dental areas.
Non vital deciduous
teeth have abnormal
resorption patterns.
www.indiandentalacademy.com
61. References
1.Handbook of orthodontics
by Robert E. Moyers
2.Orthodontic diagnosis
by T. Rakosi
Irmtrud Jonas
T.M Graber
3.Orthodontics principles and practice
by T.M. Graber
4.Contemporary orthodontics
by W.R. Proffit
5.Orthodontics current principles and techniques
by T.M Graber
R.L Vanarsdall
6.Oral pathology
by Shafer
www.indiandentalacademy.com