Removable appliances

Question 1

What movements can removable appliances achieve?

Answer 1

Tipping 
Overbite reduction
Arch expansion
Distal movement
Space maintenance
Habit breakers
Retainers

Question 2

What are the components of a removable appliance?

Answer 2

Active
Retentive
Anchorage
Baseplate

Question 3

What type of springs are there, what are their dimensions, and what type of movements can they achieve?

Answer 3

Palatal finger spring 0.5 mm - distal movement of canines, premolars and molars

Buccal canine retractor - 0.5mm - palatal and distal movement of mesially and labially angulated canines

Z spring - 0.5mm - allows proclination of one or two incisors, activated by pulling away from the baseplate

T spring - 0.5mm - labial movement

Coffin spring - 1.25mm ss - corrects buccal crossbites
alternative to midline screw

Question 4

What are the 3 types of screws that can be incorporated into a removable appliance?

Answer 4

Anterior expansion screw - labial movement - corrects anterior crossbites by proclination of multiple incisors

Midline expansion screw - allows expansion of upper arch, can correct buccal crossbites

3D expansion screw - combines both anterior and midline screw - proclines anterior segment and expands the posterior segment in upper arch

Question 5

What two types of active bows are there?

Answer 5

Labial bow - 0.7mm ss - retracts upper incisors if there is an increased OJ by tipping

Roberts retractor - 0.5mm - allows palatal movement, allows retraction of proclined and spaced maxillary incisors.

Question 6

What are the retentive components?

Answer 6

All 0.7mm ss

Adams clasp - premolars, molars

Southend clasp - anterior retention

C clasp - engages interproximal gingival undercut of canines and molars

Ball ended clasp - anterior region or upper premolars

Labial bow - can be active or retentive - used for anterior region

Question 7

What does the baseplate do?

Answer 7

Acts as anchorage
Holds intermolar width
House active and retentive components

Question 8

What are the 3 bite planes that can be incorporated into removable appliance?

Answer 8

Flat anterior bite plane - used for reduction of overbites, creates lower incisor intrusion and passive molar eruption

Posterior bite plane/occlusal capping = Helps open the patient’s bite reducing occlusal interference to help with the correction of crossbites

Inclined anterior bite plane - found on palatal surface in upper anterior segment, can be used to help a deepbite but it often used after functional applaince - holds the lower jaw in correct position and maintains incisor relationship

Question 9

Advantages of removable appliances?

Answer 9

Easier to maintain OH
Easy and quick adjustments
Shorter chairside time
Cheap
Can be used for interceptive treatment in mixed dentition
Less risk of root resorption
Anchorage is increased due to palatal coverage from baseplate

Question 10

Disadvantages of removable appliances?

Answer 10

Relies on compliance
Can only achieve tipping movement, not bodily
Can affect speech
Tolerance issues
Inefficient at multiple tooth movements

Question 11

Stages of removable appliances

Answer 11

Chairside - records and xrays, impressions, design of appliance

Lab - Construction

Fit and instructions - fit, active components activated by orthodontist, review (monitor and activate)