occlusion and malocclusion

Question 1

what is the ideal occlusion?

Answer 1

anatomically perfect arrangement of teeth- RARE

Question 2

what is normal occlusion?

Answer 2

acceptable variation of ideal occlusion
-aligned teeth
-no crowding
-class I incisor relationship- normal overjet/overbite
-class I molar relationship

Question 3

what is a normal overjet?

Answer 3

upper incisors are 2-4mm ahead of lowers

Question 4

what is a normal overbite?

Answer 4

upper incisors cover lowers by about 30%

Question 5

what is a class I molar relationship?

Answer 5

-mesiobuccal cusp of the upper 1st permanent molar occludes with the buccal groove of the lower 1st permanent molar

Question 6

define malocclusion?

Answer 6

-an irregularity in the occlusion beyond the accepted range of normal

Question 7

do all malocclusions require tx?

Answer 7

no

Question 8

define class I malocclusion?

Answer 8

the overjet and overbite are normal- molars are in the class I position.

Question 9

define class II malocclusion

Answer 9

the overjet is increased- upper incisors are even further forward that the normal accepted range.

Question 10

define class III malocclusion

Answer 10

the overjet is decreased meaning the lower incisors are ahead of the upper incisors

Question 11

what is a cause of malocclusion?

Answer 11

genetics

Question 12

how do genetics affect malocclusion?

Answer 12

genetics can affect:
-skeletal pattern
-size of jaw and teeth
-can result in syndromes such as cleft lip and palate

Question 13

describe the class I skeletal pattern?

Answer 13

normal skeletal pattern where the maxilla is 2-4 mm ahead of the mandible

Question 14

describe the class II skeletal pattern?

Answer 14

when the maxilla is >4mm ahead of the mandible- may be an associated class II malocclusion

Question 15

describe class III skeletal patterns?

Answer 15

mandible lies <2mm behind the maxilla and may be infront of maxillanum. - may be associated with class III occlusion

Question 16

how is the skeletal pattern affected in the transverse plane?

Answer 16

look directly at patient in front:
-may be asymmetry between two halves of faces
-may be discrepancy in face height- the lower third of the face may be increased or decreased in comparison to the rest of the face.

Question 17

if a patient inherits large teeth and small jaws what are they likely to have?

Answer 17

crowding

Question 18

if a patient inherits small teeth and large jaws what are they likely to have?

Answer 18

spacing

Question 19

what are other causes of malocclusion?

Answer 19

environment

Question 20

how can the environment cause malocclusion, give examples.

Answer 20

-soft tissues
-habits e.g thumb sucking
-pathology e.g tumour
-trauma
-local factors

Question 21

what is an example of soft tissues causing malocclusion?

Answer 21

-lip incompetence- where the upper and lower lip do not meet at rest

Question 22

what is an example of habits causing malocclusion?

Answer 22

e.g digit sucking- where thumb puts pressure on teeth cause them to move apart- causing an anterior open bite

Question 23

how can pathology affect malocclusion?

Answer 23

-tumours are slow growing and can exert a force on the teeth causing misalignment

Question 24

how can trauma affect malocclusion?

Answer 24

-trauma can exert an immediate force on the tooth-moving it out of alignment- e.g intrusive luxation

Question 25

how do local factors affect malocclusion and give examples of local factors?

Answer 25

-they tend to cause malocclusion in one area

-supernumerary
-hypodontia
-fraenum
-retained deciduous teeth
-early loss of deciduous teeth

Question 26

how do supernumeraries affect malocclusion?

Answer 26

-may prevent eruption of other teeth
-may cause crowding

Question 27

how does hypodontia affect malocclusion?

Answer 27

-spacing
-fixed with brace, dentures, implants

Question 28

how does the frenum affect malocclusion?

Answer 28

-labial frenum may cause a space between upper central incisors

Question 29

how do retained deciduous teeth affect malocclusion?

Answer 29

-prevents permanent tooth fro erupting in correct position

Question 30

how does early loss of deciduous teeth affect malocclusion?

Answer 30

-may cause permanent teeth to drift and erupt in incorrect position= loss of space and crowding when other teeth erupt

Question 31

what does IOTN stand for?

Answer 31

index of orthodontic treatment needs

Question 32

how does the IOTN assess malocclusion?

Answer 32

-measures the severity of malocclusion based on affects of malocclusion on dental health and aesthetics of the pt.

Question 33

how is dhc of iotn graded?

Answer 33

given score- 1-5
4/5-require treatment- greatest effect on dental health.
based on looking at overjet, missing teeth, crowding, overbite, cross bite etc

Question 34

how is the aesthetic component graded ?

Answer 34

effects of malocclusion on aesthetics
-based on graded photos to score the teeth
-1=most attractive
-10-least attractive