Oil Intrabracket Space

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Intrabracket space &

Interbracket distance: Critical factors in clinical orthodontics

Schudy GF and Schudy FF, Am J Orthod Dentofac Orthop. 1989;96:281-294

Introduction

Intrabracket space• Loose wire bracket combination

Make chairside operations easierPromote patient comfortCompromise control and undermine the

pretorquing precision

Bimetric principle• Differential slot sizing– 0.016-inch bracket in anterior segment– 0.022 or 0.018-inch bracket in posterior

segment– Smaller buccal tube in terminate area

The rationale and the actual quantitative impact of such a mechanical arrangement??

Introduction

This article– Discuss orthodontic appliance in

relationship to the desirable wire characteristics

– Report on the computer study of the impact of intrabracket space on the function of orthodontic wires

– Show the effect of intrabracket space and interbracket distance on the efficiency of the various edgewise appliances

Introduction

Appliance designs in relation to desirable wire characteristics

• Uncomplicated, easy to fabricate• Full mechanical potential• Integrated treatment functions

Looped arch wires• Decrease force• Increase range of the wire• Consume chair time to bend• Fabrication requires a skilled technician• Hygiene and tissue tolerance problems

Uncomplicated, easy to fabricate

Appliance designs

Conventional ways to minimize phasewhere good edgewise control is not possessed1. A series of round wires >> prolong treatment phase2. Largest slotted bracket with round wires or small

rectangular wires >> lack of torque control3. Small wires >> too much intrabracket space4. Nickel titanium wires >> bending poorly and high

cost5. Single bracket appliance >> longer span, more

flexible

Uncomplicated, easy to fabricateUncomplicated, easy to fabricate

Appliance designs

2 efficient ways to minimize the number of multilooped arches

• Use an appliance that automatically has a maximum amount of working wire or interbracket distance• Use smaller wires where a lack of control is

acceptable and take advantage of the maximum intrabracket space

Uncomplicated, easy to fabricateUncomplicated, easy to fabricate

Appliance designs

Full mechanical potential

Two conditions must exist:1. In the act of "seating" the wire, it must not be

stressed past its elastic limits.

2. The wire must deliver a force that is compatible with the physiology of tooth movement.

Appliance designs

Depend onInherent wire propertiesMechanical environment

• Inherent wire propertiesSmall wires: more flexibility

0.016x0.022-inch wire is

17% more flexible than 0.017x0.022-inch wire38% more flexible than 0.018x0.025-inch wire70% more flexible than 0.022x0.028-inch wire

Large wires: limits mechanical efficiency hurt the patient

additional arch wires

“It is necessary to make use of smaller wires whenever possible”


Appliance designs

• Mechanical environment– The narrow brackets

• least limiting effect on the action of wire

– The wide bracket• Severe limitation• the greater the “dead area”• the less active or “working area”


Appliance designs

Integration of

Anterior alignmentSpace closure

LevelingTorquing

Integrated treatment functions

Appliance designs

make treatment easier, more efficient and usually shorter

To achieve more integrate treatment:1. use sectional arches on the lower arch in extraction case to take advantage of physiologic drift

2. advance to a rectangular wire early in Tx


Appliance designs

Differential mechanical environment1. use small rectangular wires

2. as much interbracket distance as possible

3. as much intrabracket space as possible

4. use of two different sized bracket slots in one appliance :

“0.016 inch on anterior teeth , 0.022 inch on posterior teeth”


Appliance designs

Computer Comparison ofPopular Edgewise Appliance

• To know precisely what effect the “loose fit” in the posterior brackets has on wire capacities

• To compare single- and double-bracketed appliances in 0.016, 0.018 and 0.022-inch slots with each other and then with the bimetric appliance

Materials and Methods

• Bracket widths: 0.050, 0.100 and 0.175 inch

• Buccal slot length :0.018 inch obtain from Black’s text on dental anatomy (medium size)

• Mesiodistal tooth sizes:• Wire: stainless steel no.303

Test: Behavior of wire in bending

in six different edgewise appliances:

1. 0.022-inch twin brackets

2. 0.022-inch single brackets

3. 0.018-inch twins

4. 0.018-inch singles

5. 0.016-inch singles

6. Bimetric appliance

(0.016-inch ant. 0.022-inch post.)

0.022x0.0280.019x0.0250.018x0.0250.018x0.0250.017x0.0220.016x0.0220.016x0.0220.015x0.0190.014x0.018

Materials and Methods

General facts (within the same slot size)

Less force and greater range:• From the use of smaller wires• With single bracket• When intrabracket space is increased

Results

Force falls dramatically when wire size is smaller

0.022x0.028 (in 0.022-slot) = 8.58 lb

0.018x0.025 (in 0.018-slot) = 5.13 lb

0.016x0.022 (in 0.016-slot) = 3.56 lb

“tight-fit condition”

Results

Wire size

40.2%

30.6%

Range increases as the wire size is smaller

0.022x0.028 (in 0.022-slot) = 0.216 mm

0.018x0.025 (in 0.018-slot) = 0.264 mm

0.016x0.022 (in 0.016-slot) = 0.294 mm

“tight-fit condition”

Results

Range

12.5%

22.2%

Schudy GF and Schudy FF, Am J Orthod Dentofac Orthop. 1989;96:281-294.

Single-slot: Force decrease, range increase

“tight-fit condition ”

ResultsInterbracket distance

0.016x0.022 wire

Force Range

single twin single twin

0.016-slot 3.568 4.955 0.297 0.145

0.018-slot 3.261 4.719 0.538 0.245

8.6% 81.14%4.76% 68.96%

force decrease and range increase Less effect with twin brackets

ResultsIntrabracket space

same wire & different conditions

• “Light force and greater range”• Twisted, braided and nickel titanium wires– Less complicated to form – Working closer to their full mechanical

potential– More integrated treatment phases

• “The basic change need to be in the appliance more than in the wires”

Discussion

To receive the greatest range and lightest force:1. Large interbracket distance2. Small wires3. As much as intrabracket space as possible

Single-width bracket

It is necessary to use an appliance that incorporates differential slot sizing

Discussion

“Bimetric principle”small in front, large in back

(0.016”) (0.022”)

Popular Edgewise VS Bimetric Edgewise

“The bimetric appliance is more mechanically efficient than the traditional

edgewise appliances”

– Deflect farther before permanent set– Develop less force over greater range

Discussion

Bimetric Vs 0.018-Single Brackets

• Tight –fit (0.016x0.022 Vs 0.018x0.025)Bimetric : 68% greater range, 36% less force

• 0.001-play (0.015x0.019 Vs 0.017x0.022)Bimetric : 31% greater range, 42% less force

• 0.002-play (0.014x0.018 Vs 0.016x0.022) Bimetric : 29% greater range, 45% less force

Discussion

Bimetric Vs 0.018-Twin Brackets

• Tight –fit (0.016x0.022 Vs 0.018x0.025)Bimetric : 185% greater range, 50% less force

• 0.001-play (0.015x0.019 Vs 0.017x0.022)Bimetric : 148% greater range, 53% less force

• 0.002-play (0.014x0.018 Vs 0.016x0.022) Bimetric : 141% greater range, 57% less force

Discussion

Bimetric Vs 0.022-Single Brackets

• Tight –fit wire (0.016x0.022 Vs 0.022x0.028)Bimetric : 108% greater range, 62% less force

• Working wire(play) (0.014x0.018 Vs0.019x0.025) Bimetric : 60% greater range, 67% less force

Discussion

Bimetric Vs 0.022-Twin Brackets

• Tight –fit wires (0.016x0.022 Vs 0.022x0.028)Bimetric : 247% greater range, 70% less force

• Working wire(play) (0.014x0.018 Vs 0.019x0.025) Bimetric : 206% greater range, 74% less force

Discussion

Advantages of bimetric appliance• Fewer wires• Less complex wires• Fewer arch removals• Greater control• Greater patient comfort they are of particular significance in the

treatment of the more difficult malocclusion

Discussion

intrabracket space has nearly as much impact as does interbracket distance

Single bracket Twin bracket Wide twin bracket

10 ̊ 3̊

2̊

DiscussionClinical Implications of Intrabracket Space

• Less patient discomfort• Less complex wires• Fewer arch wires• Fewer arch removals• Faster and more efficient leveling• Reduction of permanent sets in arch wires due to mastication

• Compromises the precise and quality-oriented control of the pretorqued appliances

Advantages of intrabracket space

Disadvantages of intrabracket space


0.016 Bimetric appliance

• Finishing wire : 0.016x0.022 inch

• Anterior torque is seated easily

• Loose posterior fit in the 0.022-inch slots


Advantages of intrabracket space in bimetric appliance

• More wire flexibility and range

• Reduce friction between the bracket and the wire

• Allow horizontal shifting

• Reduce the number of permanent sets in arch

wires due to mastication


3 conditions to maximize wire

efficiency:

(1) Narrow brackets to increase interbracket distance

and the amount of working wire

(2) Smaller wires with more inherent flexibility

(3) Bracket-wire combinations that provide

maximum intrabracket space

Conclusion

For edgewise appliance:The only way to take advantage of both intrabracket space and small wires without compromising the control is to use differential slot sizing with the bimetric principle

Conclusion

• With decreasing size of teeth:– The amount of deflection decreases– The force imparted to the teeth increases

• With increasing wire size– The amount of deflection decreases– The force imparted to the teeth increases

• For single brackets – The amount of deflection is larger than double brackets – The force imparted to the teeth smaller than double brackets

• The bimetric appliance is the most flexible, allowing the most deflection with the smallest force imparted to the teeth

• The only way to take advantage of smaller wires and deliver maximum resiliency with lighter forces and not loose control is through differential slot sizing

Summary

Thank You

Discussion

Oil Intrabracket Space

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