Class 1

Question 1

What is the definition of class 1 incisor relationship?

Answer 1

the lower incisors occlude with the cingulum plateau of the upper central incisors

Question 2

What is the aetiology of class 1 incisor relationship?

Answer 2

skeletal pattern usually class 1 but can be class 2/3 and have dentoalveolar compensation
soft tissue: usually the soft tissue environment is favourable
dental factors: main aetiological agent, crowding, size of teeth relative to arch, spacing
Local factors: displaced teeth, impacted

Question 3

What is the main exception to unfavourable soft tissues?

Answer 3

bimax proclination

lack of lip tonicity

Question 4

When does crowding occur? How common is crowding amongst Caucasians?

Answer 4

When there is a discrepancy between the tooth and arch size

60% of Caucasian exhibit crowding

Question 5

What is the incidence of class 1 malocclusion?

Answer 5

60%

Question 6

What is dentoalveolar compensation?

Answer 6

a mechanism by which the soft tissues produce a more class 1 incisor relationship despite the AP relationship being class 2/3

Question 7

What intra-oral features are associated with facial asymmetry?

Answer 7

centre line discrepancies

Posterior x bite

Question 8

What should you look for if you see a posterior cross bite?

Answer 8

mandibular displacement

Question 9

why can spacing occur?

Answer 9

small teeth and normal jaw
hypodontia
normal size teeth on large jaw

Question 10

What are the causes of a posterior cross bite?

Answer 10

narrow maxilla
digit sucking
local problem often related to crowding

Question 11

What is mandibular displacment?

Answer 11

when the mandible closes from the rest position to it displaces either anteriorly or posteriorly to avoid premature contact occurring

Question 12

What type of posterior cross bites exist?

Answer 12

unilateral
bilateral
local

Question 13

When would you accept a bilateral x bite?

Answer 13

when there is no mandibular displacement

Question 14

What are the causes of disaplaced teeth?

Answer 14

Retention of primary teeth
digit habit
supernumery
cyst
tooth germ in abnormal position
crowding

Question 15

Why is bimax proclination so unstable?

Answer 15

because the lower teeth need to be retroclined which then encroaches on the tongue space therfore more likely to see relapse

Question 16

Why does late lower incisor crowding occur?

Answer 16

1. Toward growth of the mandible when the maxillary growth has slower and together with soft tissue pressures there is a reduction in perimeter for the lower labial arch segment

Question 17

What is transposition and what is pseudo transposition?

Answer 17

Transposition is when the tooth position varies eg instead of 123 it is 132. And canines are most commonly transposed
Pseudo is when the crowns are transposed but the roots are not

Question 18

What is bimaxillary proclination?

Answer 18

When the upper and lower incisors have emerged forward, making the teeth and lips protrude.

Mainly affects asians

Question 19

Which index can be used to estimate the tooth size discrepancy?

Answer 19

2mm