2- Orthodontic Appliances (Dr. Suri)

A means by which force can be applied to a tooth or a group of teeth in a predetermined direction

definition of orthodontic appliance

1. Elastics

2. Bonding

The material evolution of what 2 things changed orthodontics forever?

- Bulky

- Unesthetic

- Crude metal bands were ligated to teeth with silver or brass wires

What were characteristics of early appliances? (3)

1. Biological

2. Mechanical

3. Hygienic

4. Esthetic

What are the 4 ideal prerequisites of an orthodontic appliance?

Dr. Michael Buonocore in 1955

Who introduced acid etch technique? When?

1. Removable

2. Fixed

3. Semi-fixed

4. Functional

What are the 4 classification for orthodontic appliances?

Removable Appliances

Define the following:

An appliance that can be taken out of the mouth + reinserted by the patient

Tipping

Removable Appliances are primarily efficient in ______ movements

B - LESS chairside time

All of the following are advantages of using Removable Appliances EXCEPT:

A) Easy to fabricate

B) More chairside time

C) Less expensive

D) Oral hygiene is easy

E) Less conspicuous (noticeable)

F) In event of damage can be removed by patient

1. Only simple tipping movements can be performed

2. Multiple tooth discrepancies cannot be treated simultaneously

3. Mand appliances not well tolerated

4. Treatment dependent on patient compliance

5. Appliances can be readily broken, lost

5 limitations of using Removable Appliance

Center of resistance

Which landmark is more clinically important for predicting orthodontic tooth movement?

About one-third of the root length apical to the alveolar crest

The center of resistance of a healthy single-rooted tooth is located approximately where?

Translation (bodily movement)

If a force passes directly through the center of resistance of a tooth, the expected tooth movement is what?

1. pt comfort

2. simplicity

3. Retention

4. Strength

5. Hygiene

6. Aesthetics

6 general factors about appliance design

The nature of the tooth movement desired

What determines the appliance design?

1. Active elements

2. Retentive elements

3. Base plate

What are the 3 components of a removable appliance?

Active element

Define the following:

The component of a removable appliance that moves the tooth by applying pressure

Retentive element

Define the following:

The component of a removable appliance that holds the appliance in the mouth

Aligners

What is the most common type of removable appliance today?

Retentive element

A clasp (adams, ball, hairpin, rotowire) is what type of component of a removable appliance?

Retentive element

A pinhead is what type of component of a removable appliance?

Acrylic (PMMA)

What is the most common type of base plate material today?

Clasps

Define the following:

Retentive elements - a removable appliance that engage undercuts under the height of contour in relationship to the path of removal

Retentive and active

*gauge determines whether it is active or retentive

A labial bow has what actions?

Active element

Springs and screws are what component of a removable appliance?

To increase the range of activation

Why are loops are added to wires?

Light-cured composite resin (Ex: transbond XT)

Which material is most commonly used to bond orthodontic brackets to enamel?

Composite Resin

What type of ortho bonding materials has the following characteristics?

Properties:

- Higher bond strength

- Greater wear resistance

- Lower solubility in saliva

- More brittle/stiffer (higher modulus of elasticity)

- No fluoride release

Why?

- Highly cross-linked resin matrix (e.g., Bis-GMA) with inorganic filler particles creates a strong, rigid material

Glass Ionomer Cement (GIC)

What type of ortho bonding materials has the following characteristics?

Properties:

- Lower bond strength

- More soluble in moisture

- Lower wear resistance

- Fluoride release and recharge capability

- Chemical bond to tooth structure

Why?

Acid-base reaction between fluoroaluminosilicate glass and polyacrylic acid forms the material, producing a less rigid structure but allowing fluoride release.

Resin-Modified Glass Ionomer (RMGI)

What type of ortho bonding materials has the following characteristics?

Properties:

- Intermediate bond strength

- Fluoride release

- Better moisture tolerance than composite

- Improved physical properties compared with conventional GIC

Why?

- Combines traditional glass ionomer chemistry with a light-cured resin component.

Composite

What has the following characteristics?

- Resin matrix (plastic component, e.g., Bis-GMA or UDMA)

- Inorganic filler particles (glass, quartz, silica)

- Coupling agent (silane) that bonds the filler to the resin

- Initiator system for curing (light-cured or chemically cured)

Free-radical addition polymerization

Orthodontic composite resin adhesives polymerize primarily through what?

Camphorquinone

Which component of a light-cured composite initiates polymerization when exposed to blue light?

1. Glass ionomers

2. Zinc phosphate

3. Resin

4. Luting cement

What are some cements used in ortho (4)

5.5

What is the critical pH of enamel?

lateral incisors + molars

Where are white spot lesions typically found?

Haas Appliance

ID the appliance:

- Large bulky acrylic on palate

- Used to apply pressure against the palatal vault to expand the maxilla

Maxillary expansion

What is the purpose of a Haas Appliance?

Hyrax Appliance

ID the appliance:

- More hygienic

- Child of Haas app

- Easier to brush and floss

- No acrylic on palate

- Used for maxillary expansion

TPA (transpalatal arch) Appliance

ID the appliance:

- Has bar that crosses the palate

- Loops added to increase range of activation

- Used for maxillary expansion

Maxillary expansion

What is the purpose of a Quad Helix Appliance:

Molar distalization

What is the purpose of a Pendex Appliance?

Lip Bumper

ID the appliance:

- Eliminated the muscular forces of the lips on the teeth

- Used for patients with lower lip trap

- Allows tongue to be the only force working on the teeth if the etiology of the crowding is pressure from the lip

- Cons: molar extrusion/distalization/tipping

Lingual Arch

ID the appliance:

- Bilateral space maintainer for mandible

- Can be made active or passive

- Can regain/ open / maintain space

C) GREATER control

All of the following are advantages of using Fixed Appliances EXCEPT:

A) Compliance is not an issue

B) Controlled tooth movement

C) Less control

D) Extra-oral forces can be used simultaneously

B - EXPENSIVE

All of the following are the limitations of using Fixed Appliances EXCEPT:

A) Oral hygiene complicated to maintain

B) Inexpensive

C) Esthetically not acceptable to some

D) Longer chair-side time

E) In case of emergency patient cannot remove

F) Specialist training required

Contemporary fixed appliances

All of the following are components of what?

- Orthodontic Bands

- Orthodontic Brackets

- Arch wires

- Auxiliaries (elastics, springs, hooks)

Orthodontic bands

What has the following characteristics?

- Fabricated from Stainless Steel

- Attachments are welded

- Cemented onto teeth

Wires

______ are the means to move teeth

1. Stainless steel

2. Cobalt-chromium

3. Nickel- titanium

4. Beta- titanium

Wires are most commonly made of what 4 materials?

1. Round

2. Square

3. Rectangle

Wires usually have what 3 cross section designs:

- Iron

- Carbon

- Chromium

- Nickel

What metals are found in stainless steel?

D) Titanium

Which of the following is NOT a component of stainless steel?

A) Iron

B) Carbon

C) Chromium

D) Titanium

E) Nickel

binds to O2 preventing iron from being oxidized

How does chromium make stainless steel stainless?

Nickel

What element of stainless steel makes the metal workable/flexible?

1. Iron

2. Carbon

What 2 elements make up steel?

- 18% chromium

- 8% nickel

What is the make up for the most common composition for stainless steel wires used in orthodontics?

Stainless steel

ID the metal:

- Limited memory

- Distorts easily

- Requires shaping and heat treatment to remove stress/ strain

Nickel-titanium

ID the metal:

- Developed by NASA for space application

- Newer ones have shape memory and super-elasticity

- Worse for pts w/ nickel allergy

- 55% Ni

- 45% Ti

What is the percentage makeup for Nickel-titanium:

1st order bends

What wire bends are made in horizontal direction and influence the labiolingual/ bucco-lingual movement of teeth?

-"ins and outs"

2nd order bends

What wire bends create changes in the axial/vertical inclination of teeth (mesial/ distal tipping, extrusion/ intrusion)?

3rd order bends

What wire bends are used for root movements (labial movement of root) by creating twist or torsion in the wire?

ALL CHOICES

Which of the following are uses for elastics:

a. En masse tooth movement

b. Individual tooth movement

c. Correction of cross bites

d. Close open bites

e. Tie arch wires (elastic modules)

• intra: class I elastics

• inter: class II + III elastics

Which elastics classes are intra vs. inter arch?

Class I Elastics

ID the elastics class:

- Connects two teeth in the same arch

Class II Elastics

ID the elastics class:

- Connects maxillary teeth that are more anterior to mandibular teeth that are more posterior

Class III Elastics

ID the elastics class:

- Connects mandibular teeth that are more anterior to maxillary teeth that are more posterior

Class II Elastics

A person with a class II occlusion may benefit from what class of elastics?

Class III Elastics

A person with a class III occlusion may benefit from what class of elastics?

1. Headgears

2. Face-masks

3. Functional Appliances

What are 3 appliances used for growth modification:

Headgear

What is an extraoral appliance used for...

- Anchorage

- Molar distalization

- Control of vertical dimension *typically used for class II

Cervical Pull headgear

ID the device:

Cervical Pull headgear

What headgear is used for molar/maxillary distalization

AND produces an extrusive force?

Straight Pull headgear

ID the device:

Straight Pull headgear

What headgear produces a distalizing force with minimal eruptive force?

High Pull headgear

What headgear produces a distalizing force with molar intrusion?

High Pull headgear

ID the device:

Face Mask

ID the device:

Face Mask

What is an extraoral appliance that is used for maxillary protraction/ advancement?

Cervical Pull headgear

If a young patient as a SNA measure of 87, ( brachycephalic, euryprosopic) what device might they benefit from?

Face Mask

If a young patient as a SNA measure of 72, maxillary retrognathia with a Class II occlusion, what device might they benefit from?

Functional Appliances

What appliance?

- Stimulate reflex muscle activity which in turn produces the desired jaw and tooth movement

- Must be used during growth period of the patient

- Patient should wear the appliance full time except eating, brushing, and cleaning the appliance

- These are less successful in treating crowding and tooth irregularities

Passive tooth borne

ID type of functional appliance:

Depends on soft tissue stretch and muscular activity and have no springs

passive tooth borne

What type of Functional Appliance is a Bionator?

passive tooth borne

What type of Functional Appliance is an Activator?

passive tooth borne

What type of Functional Appliance is a Twin Block?

active tooth borne

What type of Functional Appliance is a Modified Activator?

active tooth borne

What type of Functional Appliance is a Bionator with springs/screws?

tissue borne functional appliance

Type of functional appliance that has minimal contact with teeth

tissue borne

What type of Functional Appliance is a Frankel appliance?