Ortho Lab 1

Question 1

What is orthodontics?`

Answer 1

Deals with diangosis, prevention and correction of malpositioned teeth and jaw

Question 2

What are the purpose of study models?

Answer 2

• Treatment planning
• Ortho design for removable applicances
• Checking a persons occlusion
• Secondary opinions
• Patient motivators

Question 3

Advantages of removable applicances

Answer 3

Tipping of teeth
Excellent anchorage
Cheaper than fixed applicances
Shorter chairside time required
OH easier to maintain
Non destructive to tooth structure
Less specialised training required to manage
Can be easily adapted for overbite reduction
Can achieve block movements (segmental movement if required)

Question 4

Disadvatanges for removable applicances`

Answer 4

Less precise control of tooth movement 
Can be easily removed by the patient 
Only 1-2 teeth can be moved at a time
Specialist staff to construct the applicances
Rotations are difficult to correct

Question 5

What is stainless steel wires composed of?

Answer 5

72% = Iron
18% = Chromium 
8% = Nickel
1.7% = Titanium 
0.3% = Carbon

Question 6

What are the properties of stainless steel?

Answer 6

Strong and ductile at room temp
Durable
Resist corrosion and tarnish due to the presence of chromium
Good appearance and biocompatible
Non toxic
Non cariogenic

Question 7

What are the problems with an OJ

Answer 7

Increased risk of trauma
Function problem
Appearance problems

Question 8

ARAB?

Answer 8

Active component
Retentive
Anchorage
Baseplate

Question 9

Active components? - what actually moves the tooth

Answer 9

Finger spring and guard
Z spring
Flapper spring
T spring 
     (all sit on palatal aspect with acrylic over the top = well protected 0.5mm)

Buccal canine retractor
Roberts Retractor
(Buccally placed - easily to distort, add tubing over it to give striength and rigidity)

Question 10

Retentive?

Answer 10

Resistance to displacement forces

Adams clasp 0.7mm HSSW (if decidous = 0.6mm HSSW)
Southend clasp 0.7mm HSSW
Labial bows (comes round all anterior teeth) 0.7mm HSSW

Question 11

What are the 5 internal oral forces?

Answer 11

1. Mastication
2. Gravity
3. Tongue
4. Talking
5. Active component

Question 12

Anchorage?

Answer 12

The resistance to unwanted tooth movement, making sure the tooth we want to move and keep others stable

Newtons 3rd law - every action there is an opposite and equal reaction

If moving 1/2 teeth then anchorage is fine

Question 13

Baseplate?

Answer 13

Self cured PMMA acrylic - absorbs the majority of the forces

It prevents the force over the palate preventing the whole lot moving forward

Question 14

What are the 3 functions of the basplate?

Answer 14

1. Connector - holds it all together
2. Retention - adhesion, cohesion
3. Provides anchorage

Question 15

Please construct a URA to retract 13, 23

Answer 15

Active component - 13,23 palatal finger spring and guard 0.5mm HSSW

Retentive - posterior retention - 16, 26 Adams clasp 0.7mm HSSW
- anterior retention - 11,21 Southend clasp 0.7mm HSSW

Anchorage - good as only moving 1/2 teeth

Baseplate - self cured PMMA acrylic