Orthodontic Appliances

Question 1

Do all self-ligating brackets function in the same manner during active treatment?

Answer 1

No. There are larger and smaller brackets, and active and passive mechanisms

Question 2

What are standard edgewise brackets?

Answer 2

No prescription movement was built into the bracket. All the dimensional movements were incorporated by specific adjustments to the archwires. the archwire adjustments are called first, second, and third order bends

Question 3

What are first-order bends? What is its purpose?

Answer 3

In-out bends

Which are represented by the distance of the bracket slot to the tooth surface and is a horizontal adjustment

This accommodates for the differences in the buccal tooth anatomy

Question 4

What are second order bends? What is their purpose?

Answer 4

Second-order bends refer to vertical adjustments, up and down or tip bends

They correct axial inclination and tooth-root alignment in a mesiodistal dimension

The mesial to distal tip of the bracket slot in respect to the long axis of the tooth represents this adjustment of the bracket prescription

Question 5

What are third order bends? What is their purpose?

Answer 5

Third order, or torque adjustments, refer to the bucco-palatal/lingual position of the roots in respect to the crowns of the teeth.

Question 6

True or false.. all three orders are built into the bracket by the manufacturer in contemporary edgewise brackets, and in turn meet the requirements of the straight-wire appliance

Answer 6

True

Question 7

A ____ is created as result of the distance of the force application to the center of resistance of the tooth

Answer 7

Moment

Question 8

Depending on the significance of the moment, the tooth will translate, tip, or rotate. The. Latter movements are influenced by…

Answer 8

The contact of the archwire and the bracket; thus a full-thickness archwire allows a different type of movement when compared with a thinner dimension and likely more flexible archwire

Question 9

In most instances, several stages of tooth movement occur with fixed appliances. Examples of these stages include initial level and alignment stage using ____ size wires. The wire _____ and ___ dimension increase as treatment progresses, and this allows dental arch form control

Answer 9

Smaller

Rigidity and size dimension

Question 10

What is the difference between a one and multi-piece bracket?

Answer 10

One piece bracket is rigid and manufactured usually by injection molding. A multi-piece bracket is usually milled from metal pieces and welded together to form the bracket.

Question 11

What are the components of a typical bracket?

Answer 11

Bracket base
Stem with bracket slot
Tie-wings to retain liguratures
Hook used for elastics/coils

The self-ligating brackets also include passive or active clips to secure the aarchwires

Question 12

What are active self-ligating brackets?

Answer 12

Active self-ligating brackets use a flexible component to entrap the archwire. The active component, or flexible clip, contains the archwire in the archwires slot and has the ability to store and release energy through elastic deflection. A continuous light force is imparted on the tooth and it’s supporting structures, resulting in precise and controlled moment. The appropriate bracket-archwire combination is chosen to allow low or friction-free movement when sliding of the teeth on the archwire, but use the friction provided by the clip pressing on the archwire when rotational correction is required or when a larger dimension wire is used for 3D control.

Question 13

What is the difference between active and passive self-ligation?

Answer 13

Active indicates that the spring-clip or gate mechanism is always active against the archwires. Irrespective of the wire size or archwire to bracket angulation, the clip mechanism exerts a force on the wire and thus the tooth-bracket-wire combination.

a passive system indicates that the gate mechanism or clip that entrap the archwire in the bracket slot has no active exertions of force on the archwire. Thus, the latter combination only moves the tooth through an interaction of the distorted archwire bracket interaction; the archwire engages the bracket where it has contact points and this allows tooth movement (Damon)

Question 14

What is a combined (active/passive) self-ligation system? (SPEED)

The combined clip action format is also referred to as ___

Answer 14

It has a specific bracket slot design that includes a parking ramp upon which the clip rests to prevent interaction when small dimension wires are utilized. The parking ramp enables the spring-clip to be passive during tooth movements utilizing small dimension archwires (especially for sliding) and active when tooth movement (such as torquing) is required.

Dual-action bracket spring-clips

Question 15

In the dual-action bracket spring clips, the dual action is further enhances by such characteristics as a ____ spring clip (SPEED) versus a more rigid steel clip (Damon). A different entrapment method is by a ____ mechanism or clip also fabricated from nitinol material, which grabs the archwire into the bracket slot.

Answer 15

Nitinol

Grabbing

Question 16

What are the pros and cons of a single bracket vs twin?

Answer 16

A single bracket provides a larger inter-bracket distance between teeth and theoretically allows a lighter force to act on the teeth compared wit a similar dimension wire in a twin bracket. The latter is wider and thus closer together when placed on the teeth.

However, rotations are believed to be more difficult to correct with a small and narrow single bracket

Question 17

What is a spring-wing bracket?

Answer 17

In single brackets, rotation movements are more difficult, hence the addition of rotation arms or wings are introduced. (Traditionally named Steiner wings, lang antirotation arms, or Lewis spring wings)

These wings or arms can be adjusted depending on the rotation and directions of correction required

Question 18

What is inter-bracket width?

Answer 18

Inter-bracket width refers to the distance between contact points of brackets, also referred to as the distance of archwire between two neighboring teeth. Twin brackets generally have less inter-bracket space or width compared with single brackets. A small inter-bracket width limits the size of stainless steel wire that will be able to fit in the bracket slots of adjacent teeth

Question 19

What is a single, double, or triple tube bracket?

Answer 19

These terms most frequently apply to the attachments for the first molar teeth.

When an auxiliary appliance is used in addition to the base archwire, the number of tubes need to increase. (IE headgear)

Question 20

In bonding orthodontic brackets, the enamel surface is etched with __% phosphoric acid for __-__ seconds. Then rinsed with water, dried, and sealed with a lightly filled resin

Answer 20

37%

15-30s

Question 21

True or false.. the bonding process allows brackets to be bonded successfully to amalgam, gold, acrylic, and porcelain restorations, as long as the surfaces are correctly prepared

Answer 21

True

Question 22

What are tie-wings?

Answer 22

Tie-wings are extensions of the conventional bracket. They are used for their undercuts to secure elastic or stainless steel ligatures, which in turn hold the archwires in place. In addition, tie-wings can be used to secure wire hooks, such as kobayashi tie hooks for elastic traction.

Question 23

What are the two most often used dimension of bracket slots?

What does the bracket slot dimension indicate?

Answer 23

0.018 x 0.025 inch and the 0.022 x 0.028 inch brackets

The first number indicates the width of the bracket slot occlusogingivally. The second number indicates the depth of the slot

The main difference is that the 0.022 slots can accommodate a larger selection of archwire sizes
*no evidence exists to prove that one system is superior tot eh other

Question 24

Full thickness archwires for the two bracket slot size systems are normally ____ for the 0.018 x 0.025 system, and ___ for the 0.022 x 0.028 system.

Answer 24

0. 017 x 0.025 inch

0. 021. 0.028 inch

Question 25

Two absolutely smooth surfaces of similar metals brought into contact and slid over each other can initiate a process called ____ which literally means that the metals are “fused” together. This obviously increases friction and slows movement. This happens between archwires and bracket slots

Answer 25

Cold welding

Question 26

Why do ceramic brackets often have the incorporation of metal slot inserts?

Answer 26

Because ceramic bracket slots have proved to increase friction values

Question 27

In which cases is minimal friction required to move a tooth?

Answer 27

When sliding is required, such as during the distal movement of a canine into a space.

Question 28

When sliding a tooth along an archwire, the movement should be accomplished by the use of a ___ diameter wire, which does not bind in the bracket slot. __ and ___ increase friction when used to secure archwires into bracket slots. In addition, the friction is increased when any ___ comes in contact with the ligature.

Answer 28

Smaller

Stainless steel and elastic

Minor bend in the archwire

*most self-ligating brackets have basically eliminated this limitation. Most self-ligating brackets are passive (Damon); there is no action on the wire except when there is wire bracket contact. The active self-ligation brackets have active clip mechanisms to secure the archwires into the bracket slots

Question 29

How is the SPEED bracket clip unique?

Answer 29

It prevents active contact until full-thickness archwires are used; this characteristic thus provides low friction during sliding and initial alignment when low friction is required. But it creases the friction when full-dimensional archwires are used for 3D control and when friction-free sliding is not a factor

Question 30

When is low-friction most important in orthodontic treatment?

Answer 30

Sliding and initial alignment

Question 31

Is a friction-free appliance ideal?

Answer 31

Friction-free is only an advantage when the archwire has to slide. This is most often required during the initial alignment of teeth and when spaces are closed or opened.

On the contrary, when corrective movements such as treatment of rotations, movement of severely displaced teeth in only one direction, when teeth are used as anchors, or when torquing movements of teeth are required, then friction is necessary to accomplish the correction.

Question 32

What is a convertible tube?

Answer 32

In order to provide a tube at the end of the archwire, mostly for ease of wire insertion, a tube is used for the last tooth in the arch.

A tube is fitted that has a removable plate welded over the slot to provide a slot for ease of placement of the archwire.

*therefore, when the second molar is provided with an attachement, the first molar tube is converted into a bracket by removing the plate, hence it is called a convertible tube/bracket

Question 33

What is an initial archwire?

Answer 33

The initial archwire is the first archwire in a sequence of increasing size and wire stiffness; Normally a very flexible wire that exerts a low force to the teeth and that is of small diameter

It is also required to have super elasticity and shape memory, meaning that lots of flexibility is available to allow the wire to engage all the irregularly positioned teeth without a high force caused by a deflection of the wire

Question 34

What movements does the initial archwire focus on?

Answer 34

Tooth rotations

Alignment of the marginal ridges

Followed by vertical, and then AP correction of the malocclusion using more rigid archwires

Question 35

In sliding mechanics, usually a ___ wire of [smaller/larger] dimension than the bracket slot is used in order to prevent friction that would slow movement.

What are the ways to activate this movement?

Answer 35

Stainless steel

Smaller

Powerchains, conventional elastic bands, coil springs, nitinol closing coils. This type of movement is in contrast to the traditional closing loop archwire in which the activation of the closing loop allows for the teeth to move and spaces to close where indicated.

Question 36

What is a D-shaped, C-shaped, or dual dimension archwire?

Answer 36

These wires are important when self-ligation appliances are used

The use of full-thickness archwires facilitates 3D control; thus, when D or C shaped archwires are used for this purpose, the D or C rounded side of the archwire allows easy closure of the active clip. The edge of a rectangular or square wire of the same dimension causes difficulty in clip closure; moreover forceful closure of the clip can damage the clip and negate the energy release for accurate tooth movement

Question 37

What are the properties of an ideal orthodontic archwire?

Answer 37

High elastic limit

Not too brittle

Low load-deflection rate

Resistant to corrosion

Should not fracture

Should be formed in a soft state and then heat treated to hard temper

Allow easy soldering of attachments

Question 38

Manufacturers of archwires provide which two data points to clinicians? What do they describe?

Answer 38

Cs- cross section stiffness

Ms - material stiffness

Question 39

Nitinol archwires are particularly useful when [high/low] forces and [large/small] deflections are required in relatively straight wires, such as in the initial phases of orthodontic treatment when the teeth are too irregularly aligned to use stainless steel wires.

Answer 39

High

Large

Question 40

Super-elastic nitinol wires are activated by…

Answer 40

Activated by exposure to mouth temperature

They are very flexible at room temperature and become more rigid at higher mouth temperatures.

This property allows the wire to be inserted when teeth are severely displaced

Question 41

What are TMA wires used for?

Answer 41

They have a modulus of elasticity somewhere between nitinol and stainless steel. Unlike nitinol, TMA can accommodate some adjustments, and auxiliaries can be welded to the wire

TMA can be used as an active working wire; however, it is often used as a finishing wire because small adjustments can be bent into the wire to secure perfect alignment of teeth

Question 42

Why is a power arm attached to a bracket?

Answer 42

It allows for the applied force to be closer to the center of resistance to increase the ability to control the translation or rotation/tipping of teeth

Question 43

Surprisingly, the problem with lingual races is not the ____, but rather that ___

Answer 43

Retention of the attachments on the enamel surfaces

Pronounciation difficulties. Also, this technique is difficult and time consuming. Also the interbracket distance is reduced which limits adjustments.

To facilitate treatment, customized brackets and archwires are made using scanning and computerized robotics

Question 44

Define Hooke’s law in respect to orthodontic archwires

Answer 44

If a linear relationship exists between loading and deflection, the deflection will increase when the force exerted on the wire increases

Question 45

What is the angle of torque?

Answer 45

This is the angle, viewed from an occlusogingival perspective, formed between the intersection of the line perpendicular to the tangent of the bracket base surface, and a line bisecting the bracket slot. The value is normally expressed as + or -

+ angle is directed occlusally and - if gingivally directed.