Epidemilogy/etiology Of Malocclusion

Question 1

Percentage of normal occlusion, class I, Class II, and class III

Answer 1

Normal - 25%
Class I - 50-55%
Class II - 15-20%
Class III - 1-3%

Question 2

General factors

Answer 2

Heredity
Congenital defects
Environmental
Predisposing metabolic climate and disease
Dietary problems
Habits

Question 3

Heredity

Answer 3

Homogenous racial group
Anthropologic studies
Hereditary facial type
Growth and development pattern
Dentofacial morphologic characteristics

Question 4

Congenital defects

Answer 4

Clefts of the lip and palate
Cerebral palsy
Crouzons syndrome
Cleido-cranial dysostosis
Cranial synostosis

Question 5

Environmental

Answer 5

Prenatal influence = injury/trauma, maternal diet, fetal posture, maternal consumption of alcohol and drugs
Postnatal influence = condylar fracture (whiplash injury), birth injury, accidents, avulsion or displacement of teeth

Question 6

Childhood fractures of the jaw

Answer 6

Condylar neck of mandible, 75% of early fractures have normal mandibular growth

Question 7

Predisposing metabolic climate and disease

Answer 7

High fever
Diseases of muscle dysfunction
Endocrine disorders

Question 8

High fever

Answer 8

May affect the time of eruption, resorption and formation of teeth

Question 9

Disease of muscle dysfunction

Answer 9

Muscular dystrophy, cerebral palsy, polio

Question 10

Endocrine disorders

Answer 10

Thyroid problems - abnormal pattern on resorption, eruption and gingival disturbances

Question 11

Dietary problems

Answer 11

Poor diet may cause deficiency diseases - rickets, scurvy
May cause severe malocclusion due to interference with Craniofacial growth and development in addition to periodontal problems associated with significant bone loss

Question 12

Habits and function aberrations

Answer 12

Thumb or finger sucking
Foreign objects
Tongue thrusting
Lip or cheek biting

Question 13

Function influences on dentofacial development

Answer 13

Sucking and other habits
Tongue thrusting

Question 14

Local factors

Answer 14

Anomalies of number, tooth size and shape, labial frenum
Trauma
Premature loss primary teeth
Prolonged retention and ectopic eruption
Dental caries
Improper restoration

Question 15

Anomalies of number

Answer 15

Supernumerary
Congenitally missing teeth

Question 16

Supernumerary teeth

Answer 16

Disturbance during the initiation and proliferation stages
Mesiodens
Congenital syndromes (cleidocranial dysplasia)

Question 17

Congenitally missing teeth

Answer 17

Disturbances during the initial stages of formation of a tooth
Anodontia, oligodontia, hypodontia
Congenital syndrome (ectodermal dysplasia)

Question 18

Anomalies tooth size and shape

Answer 18

Disturbances during morphodifferentiation
5% pop
Occlusion, shift, midline, space
Fusion, germination
Extra cusps vs arch length

Question 19

Abnormal labial frenum

Answer 19

Gingival recession

Question 20

Trauma

Answer 20

Damage of permanent tooth buds indirectly
Direct injury to permanent teeth (premature loss of primary teeth)
Arch contraction
Mesial drift vs distal drift
Loss of space

Question 21

Prolonged retention and ectopic eruption

Answer 21

Ectopic eruption due to over retention, crowding, position of tooth bud
Delayed eruption of permanent tooth
Impaction, rotation, drifting of teeth

Question 22

Dental caries

Answer 22

Drifting
Super eruption
Bone loss

Question 23

Improper restoration

Answer 23

Functional prematurirites
Mandibular shift
Super eruption