15. Retention

Question 1

What are the three things we want to balance to prevent an ortho case from relapsing

Answer 1

teeth
bone
muscle

Question 2

Define retention

Answer 2

holding of teeth in ideal esthetic and functional positions

Question 3

Causes of relapse are

Answer 3

• Unfavorable growth pattern may return
• Incorrect placement of teeth relative to basal bone (esp. lower anterior teeth too far anterior)
• Incorrect arch form relative to muscle function
• Lack of normal proximal contacts (tipping)
• Incorrect relationship inclined planes
• Continuation causative factors (i.e habits)
• Perio factors move teeth to move teeth to former positions
• Tooth size discrepancies
• Eruption of third moalrs
• Local hereditary characteristics (Growth factors in cell metabolism/ local tissue conditions may cause relapse tendency forever)
• Individual variations (chewing, speaking, lip/tongue/cheek)

Question 4

Over-extension is resisted by _ and over contraction is resisted by _

Answer 4

cheeks and lips… tongue

Question 5

(overjet/overbites) have the tendency to return

Answer 5

overbite

Question 6

Periapical fibers in perio membrane rearrange how often

Answer 6

8-10 weeks

Question 7

Alveolar crest (supra-alveolar) elastic fibers rearrange how often

Answer 7

1 yr

Question 8

The teeth should be held in their position until what happens

Answer 8

fibrous tissue rearranged and bone fully calcifies

Question 9

What are the limits of labial movement for the mandibular incisors

Answer 9

2 mm

Question 10

What is the limit of lateral movement of the mandibular canines

Answer 10

0 mm

Question 11

What is the limit of lateral movement of the mandibular 1st PM

Answer 11

1-2 mm

Question 12

What is the limit of lateral movement of the mandibular 2nd PM

Answer 12

2-3 mm

Question 13

What is the limit of lateral movement of the mandibular 1st molar

Answer 13

2-3 mm

Question 14

What are the different intra-alveolar fiber bundles between the root and cortical plate

Answer 14

• Crestal
• Horizontal
• Oblique
• Apical

Question 15

What is an example of hereditary characteristics that can cause relapse tendency forever

Answer 15

maxillary laterals in class II division 2

Question 16

Most ortho cases have (no retention/limiteds retentio/semi-permenant/permenant retention)

Answer 16

limited retention

Question 17

What are the different requirements of retainers

Answer 17

• Restrain teeth in current (moved) positions
• Allow functional forces to act freely
• Hygenic (smooth, polished and no porosities)
• Inconspicuous and strong

Question 18

What are the different types of retainers

Answer 18

Removable
-Hawley and variations

Fixed
-Mandibular cuspid to cuspid (like a splint)

Headgear
-May be worn with retainers above in skeletal discrepancies till the end of growth

Question 19

Impressions for retainers should be made (before/after) the removal of fixed appliances

Answer 19

before

Question 20

How long should the patient wear their retainer full time

Answer 20

1 month after braces removed

Question 21

After the first month post-treatment how many hours should the retainer be worn for and for how long

Answer 21

18 hrs…3 months

Question 22

Describe the retainer schedule

Answer 22

Full time --> 1 month 
18 hrs --> 3 months
12 hr --> 3 months 
8 hrs --> 3 months 
Alternate Nights --> 3 months 
2-3 nights/week --> forever

Question 23

Why are corrected anterior and posterior cross bites no retention

Answer 23

become open bites

Question 24

Teeth separated with regainers to allow the eruption of blocked teeth is an example of (no retention/ limited retention/semi-premanent retention)

Answer 24

no retention

Question 25

Examples of permanent/semi-permanent retention is

Answer 25

spacing (congenitally missing teeth)