1. Etiology of malocclusion
Shi Congchong
Department of Orthodontics
School of Stomatology , KMU .

2. definition ideal normal occlusion 1. save all teeth
the tooth in the upper and lower dental arch is trim
the tips of the upper and lower teeth relationship are right, upper and lower dental arch occlusal is very ideal

3. definition ideal normal occlusion individual normal occlusion
slight malocclusion, without obstruction of the physical process, can be included in the normal category
individual occlusion in the normal category, is different between each other.

4. definition ideal normal occlusion individual normal occlusion
deformities in teeth or/and maxillary(mandible) or/and craniofacial
in children’s process of growth and development
caused by congenital or acquired environment factors, such as disease, oral bad habits, etc

5. Etiology Genetic influence race evolution individual development
Environmental influence
congenital causes
acquired causes
functional influences
oral bad habits
local disturbances in primary dentition and mixed dentition

6. Genetic influence
race evolution
the change of living environment

7. Genetic influence race evolution the change of living environment
the change of structure of the food

8. Genetic influence race evolution the change of living environment
the changing structure of the food
the imbalance of degradation chewing organs
muscle>bone>teeth

9. Genetic influence
race evolution
individual development

10. Environmental influence
congenital causes
micrognathia
palate cleft

11. Environmental influence
congenital causes
supernumerary tooth can delay eruption of adjacent teeth, increase arch perimeter and lead to crowding.
Diastema, aberrant swallowing patterns and abnormal inclination of adjacent teeth can be seen as a result of congenitally missing teeth.
supernumerary tooth
congenital missing tooth

12. Environmental influence
2.acquired causes

13. Environmental influence
2.acquired causes trauma and accidents facial asymmetries

14. Environmental influence
3.functional influences
During the period of children's growth and development, the factors which can influence the growth and development of teeth, occlusion, jaw when oral system functionate. .

15. Environmental influence
3.functional influences
dysfunction of sucking
inappropriate feeding way may lead to crossbite

16. Environmental influence
3.functional influences
(2) respiratory dysfunction
-mouth breathing
rhinitis or habit or other reasons
mouth breathing

17. dental arch stenosis
upper teeth crowded
upper jaw protrusion
mandibular retraction
shortening of the upper lip
lip muscle relaxation
ala nasi atrophy
overbite and overjet

18. Environmental influence
3.functional influences
(3)abnormal swallowing
The tongue between the upper and lower teeth
upper dental arch protrusion
openbite

19. Environmental influence
4. oral bad habits
(1) suck habits
anterior teeth can not
erupt properly
openbite
thumb
sucking
dental arch stenosis
upper jaw protrusion
obstruction of nasal cavity development
fingers bend

20. Environmental influence
4. oral bad habits
(2) tongue habits
licking teeth
tongue thrusting
dental arches protrusion
openbite
mandible protrusion
anterior crossbite

21. Environmental influence
4. oral bad habits
(3) lip habits
biting lower lip
upper anterior teeth protrusion and sapcing
lower anterior teeth crowding
mandible retraction
overbite and overjet

22. Environmental influence
4. oral bad habits
(3) lip habits
biting upper lip
upper teeth inclining lingually
mandible protrusion, anterior teeth crossbite

23. Environmental influence
4. oral bad habits
(4) biting habit
local openbite

24. Environmental influence
4. oral bad habits
(5) asymmetrical chewing
waste using side with low chewing function, self-cleaning effect is poor
mandible, the center line skewing to chew side
• facial asymmetry

25. Environmental influence
5. Local disturbances in primary dentition and mixed dentition
(1) early loss of primary teeth
a single tooth loss earlier
adjacent teeth inclining
space reduced
occlusion relationship disorder

26. Environmental influence
5. Local disturbances in primary dentition and mixed dentition
(1) early loss of primary teeth
many teeth loss earlier
anterior teeth crossbite
overbite and overjet
crowding

27. Environmental influence
5. Local disturbances in primary dentition and mixed dentition
(2) delayed loss of primary teeth

28. Environmental influence
5. Local disturbances in primary dentition and mixed dentition
(3) insufficient attrition of primary caine
early contact
pain
crossbite

29. Environmental influence
5. Local disturbances in primary dentition and mixed dentition
(4) early loss of permanent teeth
(5) premature eruption of permanent teeth
(6) improper eruption sequence of permanent teeth

30. summary race evolution Genetic influence individual development
congenital causes
etiology
acquired causes
functional influences
Environmental
influence
oral bad habits
local disturbances in
primary dentition and
mixed dentition

31. summary
Nomatter which malocclusion, its closely related to body’s development and growth.
These etiology factors are related to each other not only on the classification, but also on the influence to our bodies.

32. question
What is the etiology of malocclusion?