2 - Development of the Dentition

Question 1

Eg pt has unerupted, delayed eruption of upper canine - could cause resorption of u central or lateral incisor
Or
Growth modification for pt who has severe underlying skeletal problem - if referred at correct time, at start of pubertal growth spurt - then can do this.

Question 2

Concept of ideal vs normal occlusion

What is ideal occlusion?

Answer 2

Ideal occlusion = Andrew’s six keys:

1. Correct molar relationship - (anteriorposteriorly class 1 and molars interdigitate well in buccal segments)
2. Correct crown angulation - mesial/distal tilt
3. Correct crown inclination - labiolingual inclination
4. No rotations
5. Tight contacts
6. Flat occlusal plane - so not deep overbite or anterior open bite

Question 3

What is normal occlusion?

What is malocclusion

Answer 3

Question 4

Development of deciduous dentition

1- when do deciduous teeth develop from and until
2- calcification begins when?
3- when is root formation complete after eruption?
4- when do maxillary and mandibular A-E erupt?

Answer 4

Question 5

Ideal positions for Deciduous dentition :
(4)

Answer 5

Question 6

What 3 things should we have at the completion of deciduous dentition?

Answer 6

Question 7

Deciduous incisor relationship

Explain feature of lower gum pad at birth

Is overbite normal at first and what happens over the next few years?

At 5 years what occurs?

Answer 7

Question 8

What variations often occur on ‘ideal’ deciduous incisor relationship

Answer 8

Overbite and overjet often depend on degree of thumb sucking

anterior open bite on left image
increased overjet on right image

Question 9

Spacing between incisors - deciduous dentition

1- what is the increase in intercanine width during time deciduous incisors present?

2- If deciduous incisors are not spaced what happens to permanent dentition:

3- If crowded deciduous incisors what happens to permanent dentition:

4- How much spacing is needed in the lower arch to ensure permanent incisors are aligned?

Answer 9

1- 1-2mm increase in intercanine width during time deciduous incisors present

2- if deciduous incisors not spaced -> crowded permanent incisors

3- if crowded deciduous incisors -> severely crowded permanent incisors

4- in lower arch only if > 6mm spacing of deciduous incisors will permanent incisors be aligned

Question 10

End to end E relationship

1- Ideal E relationship
2- Variations of E relationship

Answer 10

1- Es should be vertically on top of each other

2-
Class I Es -> class I 6s or class III 6s
Class II Es -> class II 6s
Class III Es -> very rare as mandible lags behind maxilla at this stage

Question 11

Problems arising during development of deciduous dentition

Abnormalities in tooth tissue ratio leads to

Answer 11

Question 12

Abnormalities in number of teeth could lead to: (3)

Answer 12

Question 13

Abnormalities in tooth form or position leads to:

Answer 13

Question 14

What can occur due to thumb sucking?

Answer 14

Also leads to increase in overjet and anterior open bite

Question 15

Incisor retrusion leads to:

Answer 15

Question 16

Posterior crossbite could be caused by?

Answer 16

Question 17

What 2 problem could we detect in deciduous dentition

Answer 17

Question 18

Development of the permanent dentition

1- starts at what age?
2- calcification dates
3- root formation:
4- what age do mandibular and maxillary 1-7 erupt?

Answer 18

If disruption eg illness at the time of the calcification may reflect in teeth being affected eg hypoplasia -if at birth could affect 6s as they calcify at this time

Question 19

Development of permanent dentition can be divided into

Answer 19

3 stages

Question 20

Stage 1 of permanent dentition eruption

Answer 20

Left DPT - lower 2 not erupted so around 6-6.5
Right DPT - all 4 lower incisors so around 7

Question 21

How is there space for permanent incisors that replace deciduous incisors?
(Space relationships in replacement of incisors )

(3)

Answer 21

1. Deciduous incisors are spaced
2. Permanent incisors are proclined (1-2mm space)
3. Increase in intercanine width:
   - slightly more in maxilla (3mm) than in mandible (2·5mm)
   - slightly more in male than female
   • in maxilla -> just enough space
   • in mandible -> 1·5mms short of space
   - transitory lower incisor crowding age 8 to 9

Question 22

Problems at stage I

Answer 22

• Impact of 6 under E
• mesial drift of 6 if E lost prematurely
• failure of eruption of incisors - supernumeraries or retained deciduous molar
• diastema and distal tilt to upper lateral incisor (NORMAL to have midline diastema at this stage)
• incisor crowding
• missing lower incisor or upper lateral incisor or abnormal form of upper incisor
• loss of permanent teeth - upper 1 or 6s
• premature loss of deciduous teeth
• incisor relationship altered by thumb sucking (posterior crossbite can also be caused by thumb sucking)
• anterior crossbite

Can also assess for anteroposterior correction

Question 23

What can you see

Answer 23

Question 24

What can you see?

Answer 24

Supernumerary between incisors in clinical photo
Supernumerary in midline between incisors in x ray - mesiodens

Bottom clinical photo - incisor rotated
Supernumerary can cause failure of eruption of permanent incisors or displacement

Question 25

What can you see?

Answer 25

If more than 6 month delay need to investigate and x ray Also history of trauma - if trauma to the A then could damage the upper incisor permanent and cause dilaceration

Question 26

What can you see

Answer 26

Question 27

What can you see?

Answer 27

Incisor crowding

Question 28

What can you see

Answer 28

Abnormal shape

Question 29

What can you see?

Answer 29

Question 30

What can you see?

Answer 30

Question 31

What can you see?

Answer 31

Question 32

Stage 2 of permanent dentition eruption

Answer 32

Question 33

Space requirements in eruption of premolars (Space relationship in eruption of premolars)

Answer 33

Deciduous teeth are larger than permanent teeth - leading to leeway space - greater in mandible than maxilla Allows Change over from E to E vertical relationship where they are on top of each other to class I buccal segment relationship- where mesiobucal of U6 is in buccal groove of L6

Question 34

E relationship How many mm of movement of lower 6 needed to give class I? Class I relationship occurs due to (2)

Answer 34

Some mandibular growth forwards along with leeway space -> permanent molar relationship of class I

Question 35

Problems at stage 2

Answer 35

change of sequence of eruption and signs of disturbance in normal development: • Delay in eruption of upper 3 - asymmetries of eruption of right and left sides - if variation is over 6 months take Xray to check cause • 5 excluded lingually, palatally, or impacted • Retained deciduous teeth, missing 5's, submerging E's Extra - Should palpate upper buccal sulcus for maxillary canine - should be able to palpate buccal and distal to lateral incisor

Question 36

What can you see?

Answer 36

Radiograph - can detect position of upper canines using upper standard occlusal and DPT - can use parallax method to determine position of the canines - to see if normal, ectopic or palatally displaced, or at risk of resorbing lateral or central incisor

Question 37

What can you see?

Answer 37

Radiograph - can detect position of upper canines using upper standard occlusal and DPT - can use parallax method to determine position of the canines - to see if normal, ectopic or palatally displaced, or at risk of resorbing lateral or central incisor If pt is 13 definitely delay in eruption and need to take radiograph to check and refer for ortho assessment if there’s a problem Left pic - palatally displaced canine, undergone Interceptive treatment with surgical exposure, gold chain on attachment Unerupted canine uses upper lateral incisor root as guidance to erupt into correct position - so if pt missing upper laterals then even more important to monitor eruption as canines likely to displace palatally - as shown in bottom right pic

Question 38

What’s this?

Answer 38

LRE - lower level of occlusal plane, become ankylosed - may become submerged - need to refer for treatment Infraoccluded

Question 39

What occurs in stage 2

Answer 39

Treatment planning for most malocclusions - space analysis space regain, space maintain or extractions (Once 7-7 erupted)

Question 40

Stage 3

Answer 40

Question 41

Problems at stage 3

Answer 41

NICE guidelines for third molar extraction (not usually an ortho problem, but oral surgery)

Question 42