W2 - Ortho Relapse / Retention - Abdalla

Question 1

What are the different orientations of gingival connective tissue collagen fibre bundles?

Answer 1

1. Periosteogingival fibres
2. Inter-papillary fibres
3. Transgingival fibres
4. Circular and semicircular fibers
5. Transseptal fibers
6. Intercircular fibers
7. Intergingival fibres

Question 2

Gingival tissue reorganisation

What is it?

Role in ortho?

Answer 2

Connective tissue fibers are twisted/stretched after ortho

• Need time to re-organise
• Otherwise, teeth will relapse

Question 3

How long does it take for periodontal fibers to reorganise

Answer 3

3-4 months

Question 4

How long does it take for gingival fibers to reorganise

Answer 4

4-6 months

Question 5

How long does it take for trans-septal fibers to reorganise

Answer 5

12 months

Question 6

What ortho movements are more prone to relapse?

Answer 6

rotations

Question 7

What is pericision aka circumferential supracrestal fiberotomy

Answer 7

Incision of supracrestal fibers around ortho treated teeth

• By cutting fibers, you speed up the rate of periodontal reorganisation
• Reduced rate of relapse in theory
• Not commonly done

Question 8

4 factors that affect retention

Answer 8

Periodontal / gingival anatomy

Soft Tisses

Occlusal balance

Growth / development

Question 9

How do the soft tissues affect occlusal positioning/balance

Answer 9

Must be equal force between tongue and cheek

• Teeth should be in the “neutral” area
• If not positioned neutrally → relapse due to force from cheek/tongue

Question 10

Answer 10

Extraction of premolars necessary

otherwise → soft tissues will press against teeth (relapse)

Question 11

What must be addressed first in these cases with lip incompetence / lip trap?

Answer 11

Lip trap must be addressed

otherwise will have soft tissue imbalance affecting ortho

Question 12

How do you measure mandibular incisor extrusion?

Answer 12

Compare mandibular occlusal plane angle to mandibular plane angle

Question 13

How does the maxillary arch change and develop over time?

Answer 13

Intercanine width increases (1.7mm btw 13-45yo)

Intermolar width decreases by 1mm by 45

Question 14

How does the mandibular arch change over time?

Answer 14

Intercanine width decreases 1.2mm (13-45 yrs)

Intermolar width decreases by 1mm (by 45 yrs)

Question 15

Why is it common to see mandibular teeth become crowded as people age

Answer 15

Intercanine width slowly decreases 1.2 mm

Question 16

Maxilla termination of growth

Answer 16

Girls - 15

Boys - 17

Question 17

Mandible termination of growth

Answer 17

girls - 17

boys - 19

Question 18

Why does the mandible keep growing after the maxilla stops?

Answer 18

Cephalo-caudal gradient of growth

• Maxilla closer to top of head, thus stops earlier

Question 19

Pros and cons of removable retainers (2 and 2)

Answer 19

Pros

• Can be worn part-time
• Can remove for cleaning

Cons

• Relies on compliance
• More intrusive

Question 20

Pro and con of fixed retainers

Answer 20

Pro

Doesnt rely on compliance

Con

More difficult to clean

Question 21

Advantages of acrylic retainers with labial bow (3)

Answer 21

• Robust- can eat without them getting damaged
• Allows posterior occlusal settling
• Anterior bite plane can be incorporated to retain corrected deep bites

Question 22

Advantages of vacuum formed retainers (5)

Answer 22

• Cheap
• Aesthetic
• Decreased speech interference
• Nighttime only
• Prosthetic teeth can be incorporated

Question 23

Pros (2) and cons (3) of bonded/fixed retainers

Answer 23

• Discreet
• Doesn’t rely on compliance

Cons

• Affects OH
• Can become active and cause mvmt
• Upper retainers can cause occlusal contact

Question 24

What happened here?

Answer 24

Stainless steel bonded retainer became active

Question 25

Which ortho treatments have limited retention (low risk of relapse)

Answer 25

* Corrected crossbites * Impacted canines treated with extraction * Dentitions where teeth have been separated to allow for eruption (Dahl)

Question 26

risk of relapse?

Answer 26

Low Limited retention

Question 27

Which ortho treatments have moderate retention (medium risk of relapse)

Answer 27

Class 1 cases Class 2 Exo cases Corrected class 1 and 2 deep bites Corrected class 2 div 1

Question 28

Risk of relapse after tx?

Answer 28

Moderate

Question 29

Which ortho treatments have high retention (high risk of relapse) (5)

Answer 29

1. Lower arch expansion 2. Rotation 3. Considerable spacing 4. Midline diastemas 5. Teeth that are placed in position outside of soft tissue envelope (think lip/cheek balance)

Question 30

Risk of relapse after tx?

Answer 30

High

Question 31

Adjunct methods to assist with retention (3)

Answer 31

Pericision Extraction of wizzies Eliminate parafunctional habits (thumb suck)

Question 32

Why is lifelong retention unlikely?

Answer 32

Dentition naturally changes with age - relapse is very likely Pts should be advised of this * Pts should only undergo ortho if they are willing and capable of following prescribed retention regimen following treatment (wearing retainers)