Growth And The Orthodontist

Question 1

What is endochondral ossification?

Answer 1

Bone develops from a cartilaginous precursor

Seen in the long bones of the limbs and the cranial base

Question 2

What is intramembranous ossification?

Answer 2

Bone is formed by osteoblasts present in the mesenchymal tissue
Takes place in the mandible, maxilla and cranial vault

Question 3

What is surface remodelling?

Answer 3

A process of resorption and deposition of bone allows the size and shape of the facial bones to change

Question 4

What is primary displacement?

Answer 4

Caused by the bone itself changing in size

Question 5

What is secondary displacement?

Answer 5

Growth of the adjacent bone such as in the change in the position of the maxilla due to the growth of the cranial base

Question 6

What are some craniofacial growth theories?

Answer 6

Sutural theory (Sicher)- this theory proposes that sutures have an innate growth potential, this has been disproved by transplanting a suture- no further growth occurred 
Cartilaginous theory (Scott)- proposes cartilage as the primary determinant of growth 
Functional matrix theory (Moss)- genetic control influences soft tissue development, this in turn determines the size an shape of the bone

Question 7

What are some orthodontic implications of growth?

Answer 7

The majority of orthodontic treatment is carried out on individuals who are still growing
In most patients 85% of their facial growth is complete but considerable growth may occur for 3-4 years after orthodontic treatment is finished

Question 8

What percentage of orthodontic cases have a growth problem?

Answer 8

5%

Question 9

What orthodontic cases have a growth problem?

Answer 9

Severe skeletal class II (insufficient growth of the mandible)
Severe skeletal class III (excess growth of the mandible)
Severe skeletal open bites (excess vertical growth)

Question 10

At age 5 what % of growth of the cranial vault is complete?

Answer 10

90%

Question 11

What is the cranial base composed of?

Answer 11

Occipital
Sphenoid
Ethmoid
Frontal

Question 12

At what age is the cranial base finished growing?

Answer 12

8-10 years

Question 13

What makes up the anterior cranial base?

Answer 13

Frontal
Ethmoid
1/2 sphenoid

Question 14

What makes up the posterior cranial base?

Answer 14

1/2 sphenoid

Occipital

Question 15

At what age does the spheno-occipital synchondrosis grow till?

Answer 15

Grows until 13-15 female and 15-17 male

Question 16

At what age does the spenoethmoidal synchondrosis fuse?

Answer 16

6-7 years

Question 17

What is the principle of growth in the mandible?

Answer 17

V principle of growth

Question 18

What is the method of growth within the mandible?

Answer 18

Endochondral in the condylar region

Intramembranous at other growth sites

Question 19

What happens during condylar growth?

Answer 19

Displacement 1st

Adaptive 2nd

Question 20

What are the principles of growth in the mandible?

Answer 20

Tuberosity growth

Chin button growth

Question 21

What is growth required for?

Answer 21

Functional appliance treatment 
Distal movement of posterior teeth 
Overbite reduction 
Spontaneous space closure after extraction 
Occlusal setting 
Use of rapid maxillary expansion

Question 22

How can the growth of maxilla be influenced?

Answer 22

It is possible to influence the growth of the maxilla using reverse pull (protraction) headgear in class III cases

Question 23

How can the growth of the mandible be influence?

Answer 23

Functional appliances may produce favourable growth of the mandible in some cases and may restrict the maxilla slightly but the majority of the effect is dentoalveolar

Question 24

When might an earlier start to treatment be advantageous?

Answer 24

In class II discrepancies

Question 25

How can you tell if growth is complete?

Answer 25

Look for good superimposition of 2-3 cephs over a 18-24 month period