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ORTHODONTIC BRACKETSSELECTION, PLACEMENT AND DEBONDING

Dr. Haris Khan

B.D.S., F.C.P.S,F.F.D RCSI

Assistant Professor OrthodonticsThe University Of Lahore Pakistan



DEDICATION

ACKNOWLEDGEMENT

CONTRIBUTOR, EDITOR AND AUTHOR

Dr. Haris Khan

B.D.S , F.C.P.S,F.F.D RCSI

Assistant Professor OrthodonticsUOL, Pakistan

COPYRIGHT

All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any formor by any means, including photocopying, recording, or other electronic or mechanical methods, withoutthe prior written permission of the publisher, except in the case of brief quotations embodied in criticalreviews and certain other noncommercial uses permitted by copyright law. For permission requests, writeto the publisher, or contact at [email protected]

I highly acknowledge the efforts and inspiration made by Dr. Ateeq ul Reham to write this book. I amthankful to Dr. Fayyaz Ahmad and Dr. Munawer Manzoor for providing me the technical guidance on various aspects of brackets. I am also thankful to Dr. Erum Bashir for doing the proofreading, Dr. lubnabatool for provided used brackets from her clinical practice and Mr Jahanzeb for doing the composingof this book.

This book is dedicated to my supervisors Dr. M. Waheed ul Hamid and Dr. Irfan ul Haq

ISBN-13: 978-1508936275

ISBN-10: 1508936277

Library of Congress Control Number: 2015905934

CreateSpace Independent Publishing Platform, North Charleston, SC

PUBLICATION DATA



In this era of pre-adjusted brackets, the existing literature on orthodontics limits itself

to wire bending treatment practices. Since contemporary authors were not trained on the

pre-adjusted bracket mechanics, hence they were handicapped to broach on the subject at

the relevant point in time. In present day orthodontics, many orthodontists still resort to wire

bending methods to close extraction spaces or to correct three dimensional positions of the

teeth.

Chapters on orthodontic brackets in various books either focus on theoretical

perspective or are devoid of essential correlation of brackets,vis-a-vis their intended clinical

use. Some authors have depicted fancy graphics to demonstrate clinical use of brackets.

To address such obvious lacunae, I started working on orthodontic brackets in the

year 2012 by collecting the brackets which were debonded during my clinical practice.This

took me through the entire literature on orthodontic brackets as presented in various journals

and manufacturer catalogues. This provided me an access to real time pictures of brackets

using special micro lenses and portable microscopes.

This book was authored to cater for all aspects of orthodontic brackets. The focus

being to provide students with real time pictures of different brackets available in the market

and to determine their behaviour in oral cavity and their appearance after debonding. The

main emphasis being on three vital aspects viz; the selection, placement and debonding,this book has accordingly been designed to comprise these three sections. Real times of new and

used brackets have been specifically included to provide the students a realistic insight of

brackets.Care has been taken to ensure correlation of clinical situation and various bracket

selection criterions.

This book has materialized after an enormous effort of two years in data collection

and a year further in arranging the data in a convenient book form.

I deeply acknowledge the help and encouragement provided my colleagues inconsummating this endeavor.

I earnestly hope that this effort would go a long way in providing ready help to

students.

Haris Khan



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13

1

Table of Contents

Historical Perspective of Orthodontic Brackets

Selection of Auxiliary and Convenience features

Debonding of Orthodontic Brackets

Material Perspective of Orthodontic Brackets

Selection of Bracket Prescription

Adhesive Remnants Removal

Selection of Bracket Base

Placement of Orthodontic Brackets

Recycling of Orthodontic Brackets

Selection of Bracket Slot

Bonding in Orthodontics



1 C

H A P T E R

Historical Perspective of Orthodontic Brackets In this Chapter

History

Pierre Fauchard

Modifications of bandeau appliance

Development of edgewise appliance

E Arch

Pin and Tube Appliance

Ribbon Arch Appliance

Edgewise Appliance

Begg Appliance

Other Appliances

Modification of Standard Edgewise Appliance

Self ligating brackets

Light wire Appliances

Lingual brackets

Customized labial brackets

Orthodontic brackets are important part of fixed

appliances which are temporarily attached to

the teeth during the course of orthodontic

treatment. They are used to deliver forces from

the wires or other power modules to the teeth.

Before going into the details of orthodontic

brackets a historic preview on the evolution of

brackets is given.

History

The origin of orthodontic brackets can well be

coined with the origin of orthodontics and the

human desire to align crooked teeth. The first1

written record to correct crowded or protruded

teeth is found 3000 years ago. Orthodontic

appliances to correct maligned teeth have been

found in Greek, Etruscan and Egyptian artifacts2.These ranges from crude metal wire loupes to

metal bands wrapped around individual teeth in3

ancient Egyptian mummies . Pliny the Elder

(23-79 AD) was the first to mechanically align4elongated teeth .

Pierre Fauchard

Pierre Fauchard (1678 –1761) a French dentist

was the first to make a scientific attempt to align

irregular teeth by an appliance named Bandeau

(Figure 1.1 & 1.2).This appliance was made of

precious metal and it was shaped like a horse

shoe to align teeth by arch expansion. Fauchard

also used to reposition irregular teeth with his

Pelican forceps and then ligate them with

neighboring teeth until healing took place.

Fauchard published his work in 1728 in his

landmark book entitled The Surgeon Dentist: A

Treatise on the Teeth.

1



1CHAPTER

H i s t o r i c a l p e r s p e c t i v e o f O r t h o d o

n t i c B r a c k e t s

Figure 1.2 Bandeau Appliance

2

Modifications of bandeau appliance

Fauchard's bandeau appliance was further

refined by another fellow French dentist

Etienne Bourdet (1722-1789) who was a dentist

to the King of France in his time. Etienne

Bourdet was also the pioneer of lingual

orthodontics by expanding the arch by metal

framework placed on the lingual side.

Christophe François Delabarre (1787-1862)

another French dentist used swelling threads

and wooden wedges to separate crowded teeth.

Horace H. Hayden (1769-1844) invented bands

with soldered knobs to correct tooth rotation.

In 1803, Joseph Fox invented a modified

version of bandeau appliance that consisted of

silver or gold rim. Silk thread was used as mode

of attachment and force transfer between the

rim and teeth. These silk threads were adjusted

after every three weeks (Figure 1.3a). Blocks of

ivory were used to disocclude the occlusion and

to prevent interference with tooth movement. J.

M. A. Schange (1841) a French dentist wrote the

first book exclusively on orthodontics. He

modified bandeau appliance and took

anchorage by skeletal cribs attached to molars

(Figure 1.3 b). He also invented an appliance to

move malposed teeth within the arch (Figure

1.3 c).Harris in 1850 attached metal caps to

molar and took anchorage from palate in his

expansion appliance (Figure 1.3d)

Development of edgewise appliance

Norman W. Kingsley (1825-1896) and Calvin

S. Case (1847-1923) advocated extraction for

orthodontic purpose. Though Norman W.

Kingsley later abandoned his extraction

philosophy. This extraction philosophy later

influenced the basic design of orthodontics

braces.

5Edward Hartley Angle (1855-1930) was the

most dominant and influential figure in

orthodontics and is regarded as the “Father of

Modern Orthodontics.” (Figure 1.4). Because

of Edward Angle, orthodontics was recognized6

as a distant and separate science from general

dentistry. In his initial days of orthodontic

practice Angle advocated extraction in

orthodontics .But latter on the basis of Wolff's

law that “bone in a healthy person will adapt to

applied load” Angle abandoned extraction

treatment. Also another reason to abandon

extraction treatment was failure to get

satisfactory result after extracting 1st maxillary

Figure 1.1 Pierre Fauchard



2 C

H A P T E R

Material Perspective of Orthodontic Brackets In this Chapter

Introduction

Manufacturing Techniques

Casting

Milling

Sintering

Metal injection molding (MIM)

Ceramic injection molding (CIM)

Plastic injection molding (PIM)

Brazing

Cold working

Metal Brackets

Stainless steel brackets

Cobalt chromium brackets

Titanium brackets

Precious metal brackets

Plastic Brackets

Plastic Polyoxymethylene brackets

Polyurethane brackets

Composite plastic brackets

Ceramics Brackets

Aluminum oxide or Alumina (Al O ) brackets2 3

Monocrystalline brackets

Polycrystalline brackets

Zirconia brackets

Calcium phosphate ceramic brackets

Introduction

Contemporary orthodontic brackets are

modification of a standard edgewise brackets

developed by Edward H Angle. At the time of

edgewise brackets invention stainless steel

alloy although invented was in the phase of

evolution and orthodontic brackets soldered to

bands were largely made of 14 karat or 18 karat1

gold. Rudolf Schwarz was the first to use

stainless steel in edgewise appliances. ErnestSheldon Friel (1888-1970) a pupil of the Angle

(Angle School, 1909) used stainless orthodontic

bands for the first time in 1935.Apart from

stainless steel different other materials have

also been introduced with time to meet the

orthodontists and patient's need. Modern

orthodontic brackets are made up of three

different types of materials which are as follow :

13



Cobalt chromium brackets were introduced in

mid 1990s as a low nickel alternative to stainless

steel. Cobalt chromium brackets are fabricated

from casting or metal injection molding.

Type and Composition of Cobalt based alloys

Cobalt based alloys can be divided into three

categories .These are:

1. Cobalt based wear resistant alloys

2. Cobalt based high temperature alloys

3. Cobalt based corrosion resistant alloys

In these alloys cobalt based wear resistant alloys29

are used presently for orthodontic brackets

manufacturing .In cobalt based wear resistant

alloys CoCr brackets are made from ASTM F-

75 CoCr where ASTM stands for American

Society for Testing and Materials. The amount29of nickel in this alloy is kept low and is up to

0.5 %. Composition of cobalt based wear

resistant alloys is given in table 2.3. A cobalt

chromium bracket is shown in figure 2.19.

Selection of Stainless steel brackets

Stainless steel brackets with good corrosion

resistance should be selected. Good corrosion

resistance of a bracket is more important than

its nickel contents. Ideally SS brackets shouldnot be used for nickel sensitive patients.

Conventional SS brackets with softer base

component and harder slot/wings component

should be preffered.17-4 PH MIM brackets

are a good choice for proper torque

expression. New bracket should always be

the first choice by orthodontists to avoid

corrosion.

Table 2.3 Cobalt-Base Wear-Resistant

Alloys

Cr 25-30%

Mo 7% max

W 2-15%C 0.25-3.3%

Fe 3% max

Ni 0.5%max

Si 2%

Mn 1%

Co Balanced

Where Cr=Chromium, Mo=Molybdenum, W =

Tungsten, C =Carbon, Fe = Iron, Ni=Nickel, Si

= Silicon

Properties of Cobalt ChromiumBrackets

Friction Resistance

In terms of friction resistance cobalt chromium30, 31

brackets show comparable but slightly less

amount of friction than that of stainless steel

brackets when used with stainless steel wires.

But CoCr brackets offer more friction than30

titanium brackets with both stainless steel and

beta titanium wires.

Corrosion Resistance

Because of increase chromium contents there is32

less chance of corrosion of cobalt chromium

brackets.

Figure 2.19 Nu- Edge® Mini Cobalt Chromium Brackets by TP orthodontics with 0.5 % nickel.

27



Titanium Brackets

Titanium metal has excellent biocompatibility18, 33, 34

and increased corrosion resistance so it has

wide ranging surgical application from artificial

heart valves and hip joints to dental implants.

In orthodontics to overcome the release of

nickel from stainless steel brackets which may

cause nickel allergy in some patients, titanium35, 36

brackets have been introduced as nickel free

alternatives to stainless steel in mid 1990s.

Types of Titanium

From material science perspective titanium has

the following three types:

1. αTitanium

2. β titanium

3. α &β Titanium

Alpha titanium is commercially pure (CP)

unalloyed titanium while the other two types are

titanium alloys.β titanium include Ti-15V-3Cr-

3Sn-3Al alloy while α-β titanium included Ti-

6Al-4V alloy. Alloyed titanium has greater

strength than unalloyed titanium. Chemicalcomposition of various types of titanium is

given in table 2.4.

Commercially pure (CP) titanium is further

classified into four grades depending upon

degree of impurity, primary oxygen within the

unalloyed titanium. Grade 1CP titanium has the

lowest strength but highest purity, corrosion

resistance and formability as compared to grade

4 CP titanium, which offers highest strength and

moderate formability. Composition of different

grades of CP titanium is given in table 2.5.

21, 37Contemporary titanium brackets are either

manufactured from alpha titanium grade 2 and 4

or alpha-beta titanium (Ti-6Al-4V).Grade 2 CP

titanium is usually used to make base

component of brackets due to its decreased

strength while the wing component is made

from much harder titanium alloy, the alpha -beta

titanium Ti-6Al -4V.Both these components are

laser welded to make a single unit of bracket. As

explained before for stainless brackets

combination of harder slot/wings part and softer

base part has clinical importance. The softer

base part will allow easy mechanical debonding

while harder slot/wings part will allow

expression of torque.

37Due to release of vanadium from titanium alloy

Ti-6Al-4V which may have biological

hazardous effects some manufacturer make

single unit milled or metal injection molded

bracket from grade 4 CP titanium.

Characteristics of Titanium brackets

Corrosion Resistance

Titanium and titanium alloy brackets have

greater corrosion resistance than stainless steel

brackets. This is due to the presence of thin

passive protective layer of titanium dioxide

over the titanium. This layer of titanium dioxide23

is more stable than its counterpart layer of

chromium oxide on stainless steel. The

composition of titanium dioxide layer which isalso called rutile is given in table 2.6.

Brackets in which two parts are joined together

by welding have greater chances of galvanic

corrosion than one piece milled or MIM

brackets. A titanium bracket is shown in figure

2.20.

Selection

Cobalt chromium alloys have good corrosion

resistance and have a highly polished surface.

But due to less favorable friction properties

with different types of wires, selection ofCoCr brackets over titanium and steel

brackets is a matter of personal choice than

logical basis.

2CHAPTER

M a t e r i a l p e r s p e c t i v e o f O r t h o d o n t i c B r a c k e t s

28



than conventional ceramic brackets and these

brackets don't cause enamel damage.

Selection of ceramic brackets

Ceramic brackets are usually selected for

patients who have aesthetic concerns. Due toiatrogenic damages associated with ceramic

brackets they should only be selected when

clinicians have proper knowledge of

mechanics and proper instrumentation for

debonding is available.

Monocrystalline brackets give better

aesthetic than polycrystalline brackets but are

more expensive and fracture easily and more

with time. Zirconia brackets are rarely used in

contemporary orthodontics. Calcium

phosphate ceramics is manufactured by only

one company and not much is known about

these brackets so selection of these brackets is

a personal preference.

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strength and debonding characteristics. Am J Orthod Dentofacial

Orthop. 2003 Sep;124(3):309-15.

75. Monticello J. The comparative shearing strength of five

contemporary ceramic brackets, master's thesis,University of Detroit,

1990.

76. Springate SD, Winchester LJ. An evaluation of zirconium oxide

brackets: a preliminary laboratory and clinical report. Br J Orthod1991; 18: 203–9.

77. Keith O, Kusy RP, Whitley JQ. Ziconia brackets: an evaluation of

morphology and coefficient of friction. Am J Orthod Dentofac Orthop

1994; 106: 605–14.).

78. Meguro D, Hayakawa T, Kawasaki M, Kasai K. Shear bond strength

of calcium phosphate ceramic brackets to human enamel. Angle Orthod.

2006 Mar;76(2):301-5.

2CHAPTER


40



3 C

H A P T E R

Selection of Bracket Base

In this Chapter

Bracket Base Retention Design

Stainless steel Brackets

Mechanical Retention

Perforated bases

Mesh type bases

Integral bases

Photoetched bases

Microetced bases

Metal sintered bases

Laser structured bases Plasma coated brackets

Chemical Retention

Stainless steel brackets and Crossinfection

Titanium Brackets

Cobalt Chromium Brackets

Precious metal Brackets

Plastic Brackets

Chemical Retention


Combination of chemical and mechanicalretention

Ceramic Brackets

Chemical Retention


Micromechanical retention

Ceramic brackets with prestressed base

Combination of different retention designs

Bracket base surface area

Bracket base shape

Bracket identification marks

Torque in the Base

The base component of orthodontic bracketsmakes possible the attachment of a bracket to

the tooth. This attachment must be strong

enough to transfer orthodontic forces from the

wires to the teeth, withstand masticatory loads

and should easily be removed at the end of

treatment.

Bracket Base Retention Design

Orthodontic brackets are attached to teeth or

other supporting structures of porcelain, metal,

composite and acrylic through various

commercially available adhesives. To increase

retention of bracket bases to adhesives various

chemical, mechanical or combination of both

retention designs have been added to the bracket

base. Though the exact manufacturing details

41



are not provided from the manufacturer some

basic informations are available.

1) Stainless steel Brackets

Most or thodont ic bracket s used in

contemporary orthodontics are made ofstainless steel which mostly uses mechanical

retention because stainless steel doesn't form

any chemical union with adhesives. Stainless

steel bracket base is either integral part of the

bracket or is made separately and then joined

to the main body of the bracket by brazing or

welding (Figure 3.1).Different types of

stainless steel bracket bases are given in the

following text.

1. Perforated bases

Brackets with perforated bases are one of

the oldest bracket designs for mechanical1

retention (Figure 3.2). The original metal

pad consists of one row of peripheral

perforation. The basic idea was to allow

greater penetration and free flow of

adhesive cement through the bracket base

to increase the bond strength. But

unfortunately excessive adhesive comingout of the holes of bracket base was

potential plaque retention area which get

discolored with time so raised esthetic

concerns by the patients and don't provide

superior retention as compared to other2 , 3 , 4 , 5 , 6

designs . Because o f these

disadvantages perforated bracket bases

went into disuse.

2. Mesh type bases

Mesh type bases have replaced perforated

bases and are most popular type used in

contemporary orthodontics. Following

different terms are used for mesh based

bases in literature and by manufacturer

owing to slight variation in mesh design.

a) Foil mesh base

b) Gauze or woven mesh base

c) Mini mesh base

d) Micro mesh base

e) Optimesh base

f) Ormesh base

g) Laminated mesh base

h) Single mesh base

I) Double mesh base

j) Supermesh base

Description of some important mesh

designs is as follows.

a) Foil mesh base

In orthodontic literature the term foil

mesh base is used interchangeably with

gauze or woven mesh base. But there are

slight differences in the manufacturing

design between foil mesh and woven

mesh base (Figure 3.3) .Foil mesh bases

are more esthetic and hygienic than

perforated bases because of their smooth2, 3, 7, 8

covered surface . Foil and woven

mesh bases provide superior retention

than perforated bases and many other

b r a c k e t b a s e d es i g n s u s e d i n4, 7, 9

contemporary orthodontics . Foil mesh

bases can be simple or microetched,

photoetched or plasma coated by the

manufacturer. The foil mesh is either

brazed or welded on to the bracket base.

The spot welding of foil mesh to bracket

base results in decreased base surface2, 4, 10

areas and so bond strength therefore

spot welding have been taken over by11

silver based laser welding .

Foil mesh bases can be single mesh or

double mesh.

CHAPTER 3CHAPTER

S e l e c t i o n o

f B r a c k e t B a s e

42



of increasing or decreasing the bracket base

surface area. Proffit48 purposed that width of

the bracket shouldn't be more than half of the

width of the tooth while MacColl49

recommended that bracket base surface area

should be around 6.82 mm2. Usually the

manufacturer of brackets keep a larger base

area to give better bond strength and rotational

control .

Clinical implication of Bracket basesurface area

Increase Bracket base surface area

Advantages

This has the following advantages:

1. Increased bond strength. This is helpful

especially in case of plastic brackets which

offer less bond strength than other type of

brackets. Clinically acceptable bond

strength50 is around 5.9 to 7.8 Mpa but bond

strength shouldn't exceed51

than 13.5Mpa to

avoid enamel damage.

Bracket base surface area

An important technical specification that affects

the bond strength of orthodontic bracket is its

base surface area. Most orthodontists presently

use twin brackets. The surface area26,47

of these

brackets range from 12.5mm2 to 28.5 mm

2.

Greater the retentive bracket base area greater

would be the bond strength and vice versa

(Figure 3.27). But there is practical limitations

lower bond strength than high filled

adhesives.

Another alternative is to use glass ionomer or

resin modified glass ionomer 41 cements

(RMGIC) with ceramic brackets as glassionomer cements have shown to have

decreased42,43

but clinically acceptable bond

strength32, 44, 46

than composite resins . Though

bond failure of glass ionomer cement is

present at enamel adhesive interference but

no enamel damage is reported44, 45

with this

adhesive cement because RMGIC has lower

bond strength.

Glass ionomer cement also has the added

advantage of fluoride release and so it

prevents enamel decalc if ication and

formation of white spot lesions during

orthodontic treatment.

Selection of ceramic bracket base

Ceramic bracket base using only chemical

retention is neither marketed nowadays nor

should be used due to risk associated with

enamel damage. All other commerciallyavailable ceramic brackets are acceptable for

orthodontic purpose as long as suitable or

recommended debonded techniques are

used. My personal recommendation after

going through all the available literature and

personal experience is that ceramic brackets

with plastic base or prestressed base should

be used as it debond safer than other base

types.

Figure 3.27 Greater the retentive bracket base surfacearea greater would be the bond strength.If the base surfacearea is not retentive then no matter how much wider is the

bracket the bond strength will remain minimum or bracket will fail to bond. The above brackets havemanufactur ing faults which have increased the surfacearea but area is not retentive. So instead of favoring bondstrength the area can act as plaque reservoir and may leadto development of white spot lesion under the bracket

base.

CHAPTER 3CHAPTER

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56



4 C

H A P T E R

Selection of Bracket Slot

In this Chapter

Introduction

Type of bends for 3 dimensional toothmovements

Dimensions of Edgewise slot

Accessary slots

Tip edge brackets

Advantages of 0.018” slot

Advantages of 0.022” slot

Bidemensional mechanics

Morphology of the brackets

Gingival offset brackets

Slot modifications to reduce friction

Ligation: The fourth wall of Bracket slot

Tie Wings of the brackets

Introduction

Slot is part of the bracket in which the wire is

engaged to express the builtin prescription of

the bracket. The slot of the bracket has seen

much evolution with time. It started from

occlusal opening slot in Angle ribbon arch

appliance to gingival opening slot in Begg

appliance and front opening slot in Angle

edgewise system. In contemporary orthodontics

edgewise slot is universally accepted .Vertical

slots are still used in some bracket series but

usually as an accessary slot.

When bracket slot was first introduced they

were simple openings in which a bended wire

incorporating all the necessary tooth

movements was inserted. The brackets having

such passive slots were called standard

brackets. With time 1st, 2nd and 3rd order bends

were incorporated in brackets to produce1

respective tooth movements . Before going into

the details of slot a brief description of these

bends and associated movements are given.

Type of bends for 3 dimensional tooth

movements

First order bends (In or out bends)

First order bends are given to accomplish firstorder tooth movements which are in a

labiolingual or buccopalatal direction. 1st order

bends can be made in horizontal direction in the

wires such as the step bends, or are

accommodated in the brackets (Figure 4.1). As

different teeth in the arch have different width

these bends made in the wire or built into the

bracket are used to accommodate different tooth

width. Vertical step bends that don't change the

61



angulation of the teeth are also considered as 1st

order bends. First order bends in brackets are

incorporated by increasing the prominence of

the bracket.

Second Order Bends (Tip or Angulationbends)

These bends are made in vertical plane in the

wire to accommodate tooth angulation and root

parallelism. Second order bends can also be

incorporated in the brackets by placing the slot

at an angle to the base (Figure 4.3).

Figure 4.1 A. A line showing different prominence of the teeth in natural dentition due to difference in width of the teeth. B. Wire bending done to compensate 1st order tooth movement. This type of wire bending is usually done in conventional edgewisesystem. C. First order bends built within the bracket. This is evident with different prominence of the brackets in upper arch.

Figure 4.2 Maxillary lateral incisor brackets from twodifferent manufacturers having same builtin prescription.The height or prominence of these brackets is different.

Clinical NotesThe clinician should always use same

companie's brackets. If a bracket is

debonded either the bracket should be

recycled and reused or a new bracket of

same company should be used. Different

companies have different prominence of

the brackets(Figure 4.2). So using different

companie's brackets will result in first

order tooth position problems in a finished

case.

Clinical Notes

Different bracket prescription have

different builtin tip. An experienced

clinician can use combination of brackets

from different prescription provided that

they have the same prominence. It is a good

practi ce to use bracket s of sing le

manufacturer whi le a l t e r ing the

prescription.

A B

C

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5 C

H A P T E R

Selection of Auxiliary and convenience features In this Chapter

Auxiliary features

Power arms

Accessary slots

Convenience features

Vertical Mid Scribe line

Shape of brackets

Bracket identification

Many auxiliary and convenience features are

added to the brackets and tubes to make

treatment mechanics easier and convenient.

Auxiliary features

Power arms

Power arms are added to the brackets on its

gingival side to control root position during

translation of the teeth. The reason for making power arms on gingival side is to bring the force

application closer to the center of resistance of1

the teeth. Andrew proposed that for effective

control of root position during translation, the

mesiodistal length of bracket plus height of

power arm should be equal to distance from the

slot point to tooth center of resistance (Figure

5.1). As root of canine is longer than other teeth

so power arm of canine tooth would also be

longer than other teeth. But there are practical

limitations in increasing the width of bracket

and height of power arm. A wider bracket will

decrease interbracket distance so increasing the

wire stiffness and thus greater time would be

needed in alignment and leveling. Also a wider

bracket will be more noticeable, thus increasing

aesthetic concerns of the patients. The height of

power arm is limited by soft tissue present

around the tooth as long power arm willimpinge on the gingiva either making ideal

bracket placement difficult or leading to

gingival hyperplasia due to soft tissue

impingement.

Advantages of power arm

1. Power arm makes the application of force

delivery system such as springs, power

chains, and elastics much easier and close to

77



Selection of Bracket Prescription In this Chapter

Introduction

Andrew Prescription

Key I: Interarch Relationship

Key II: Crown Angulation orMesiodistal Crown tip

Key III: Crown inclination or Torque

Key IV: Absence of Rotations

Key V: Tight Contact points

Key VI: Flat Occlusal plane or Curve

of Spee

Limitations of Andrew prescription

Different Bracket prescriptions

Roth Prescription

Limitations of Roth Prescription

MBT Prescription

Alteration of prescription

Introduction

Angle introduced edgewise brackets to have a

better control on three dimensional positions of

the teeth. But the problem in these brackets was

that complex wire bending was required to1,2

control the tooth position. Andrew modifiedthe standard edgewise brackets developed by

Angle by introducing tip, torque and in& outs in

his preadjusted edgewise brackets .The amount

of tip torque and in & outs built within

preadjusted brackets were called prescription of

the brackets. After Andrew a lot of orthodontists

introduced their versions of bracket prescription

sometimes based on studies and many times

based on clinical experience. Each clinician

who advocated a specific prescription also

advocated specific mechanics during the course

of treatment for expression of the prescription.

In medicine to treat a disease properly, the right

diagnosis should be made. That helps the

physician to advise the right prescription ofdrug .Same is true in orthodontics. After making

a right diagnosis and treatment planning of a

malocclusion the right prescription should be

used. Using the right prescription, simplify the

treatment mechanics which will save

considerable chairside time. In most cases there

would be minimal or no need of wire bending

during the course of orthodontic treatment.

6 C

H A P T E R

83



A detailed description on evolution of different

types of orthodontic prescriptions is given in

this chapter. Main focus is given to the

development of Andrew prescription because

all other prescriptions are either variations or

based on Andrew's data.

Andrew Prescription

1Lawrence F. Andrew introduced the first

preadjusted brackets where all the bending's

needed in archwire in standard edgewise

bracket system were built within the brackets. It

was proposed that this appliance does not

require wire bending during treatment hence the

name Straight wire appliance (SWA) was given

to it.

Andrew after a study on 120 non-orthodontic

ideal occlusion dental casts concluded that in

order to attain ideal occlusion some

characteristics must be present within the

occlusion. These characteristics were divided

into six keys. Based on these 6 keys Andrew

developed his prescription of brackets, so that

using this bracket prescription no wire bending

would be required during treatment and at the

end of treatment, all the six keys to normal

occlusion would be attained.

Andrew apart from studying these non-

orthodontic ideal occlusion dental casts also

studied 1150 orthodontic treated cases so that

his prescription could also address some of the

problems not found in ideal occlusion e.g.

Extraction cases where molar relation may

deviate from class I relationship.

Most of the modern preadjusted brackets are

minor modification of Andrew straight wire

appliance. To give a better understanding of

prescription so that clinician can make an easy

selection of brackets a complete description of

Andrew six keys to normal occlusion and how

prescription components evolve from each key

is given. Details on how a prescription in

bracket is transferred to a tooth are also given

with each key so that the readers can have a clear

knowledge of effects and limitations of a

prescription.

Key I: Interarch Relationship

1Key I as originally proposed by Andrew was2

molar relationship. But in 1989 Andrew

changed the key from molar relationship to

interarch relationship. Interarch relationship is

broader and more definite description of

occlusal relationship than relying on molar1

relations only. Interarch relationship as key is

considered in this text because it will clear the

reader's mind about the basis and need of

prescription.

2Key I have seven parts which are given below:

Part 1

The mesiobuccal cusp of the maxillary first

permanent molar fits in the groove between the

mesial and middle buccal cusps of the

mandibular first permanent molar.

Part 2

The distal marginal ridge of maxillary 1st molaroccludes with mesial marginal ridge of the

ndmandibular 2 molar.

Previously1 this relation was. "The distal

surface of the distobuccal cusp of maxillary 1st

molar made contact and occluded with the

mesial surface of the mesiobuccal cusp of the

mandibular second molar." The closer these

two surfaces of maxillary 1st and mandibular

2

nd

molar contact and occlude , the betterwould be the opportunity for normal

occlusion.

Part 3st

The mesiolingual cusp of the maxillary 1

permanent molar occludes in the central fossa of

mandibular 1st permanent molar.

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84



Part 4

The buccal cusp of the maxillary premolars

have cusp embrasure relationship withnd

mandibular premolars. The maxillary 2

premolar buccal cusp lies between embrasure of

mandibular 1st molar and mandibular 2nd

premolar. Buccal cusp of maxillary 1st premolar

lies in the embrasure between mandibular 1st

and 2nd premolars.

Incorporat ing key I into bracket

prescription

Key I is interrelated with next 5 keys to normal

occlusion. Key I will only be achieved when the

rest of the keys have been achieved too.

To attain key I, a preadjusted bracket shouldst nd rd

have built in 1 , 2 and 3 order bends and

brackets should be optimally placed on the

tooth. Only description of 1st order bends and

how and why they are included in the

prescription would be given here. The rest

would be discussed in their respective keys.

To incorporate the right amount of 1st order

bends with in his prescription Andrew

2

measured the facial prominence of each tooth

within the arch of an ideal occlusion

case .This was done by measuring the distance

from the embrasure line to most prominent

facial point of each tooth, where embrasure

line is imaginary line at crown mid transverse

plane that connects the facial portion of

contact areas of a single crown or all the

crowns in an arch when the crowns are

optimally placed. Figure 6.2 and table 6.1.

From the figure 6.2 and table 6.1 it is clear that in

maxillary arch lateral incisors have least facial

prominence while in mandibular arch both

central and lateral incisors have least facial

prominence. These values were built within the

base or stem of the brackets so that at the end of

leveling and alignment all the brackets slots

Figure 6.1 An ideal occlusion case meeting all the criteria of key I . A .Buccal aspects . B. Lingual aspects

Clinical Notes

To check if a case has attained Key I,

always judge from buccal aspect clinically

and both from buccal and lingual aspects on

the dental cast.

A B

Part 5

The lingual cusp of the maxillary premolars has

a cusp fossa relationship with mandibular

premolars.

Part 6

The maxillary canine tip lies slight mesial to the

embrasure between mandibular canine and 1st premolar.

Part 7

The maxillary incisors overlap the mandibular

incisor with their dental midlines coinciding.

A description of key I is given in figure 6.1.

85



have same level of prominence while all the

teeth have the prominence value found in table

6.1.

How it works?

To build the right amount of prominence withinthe brackets, Andrew incooperated a simple rule

that the distance between most prominent facial

point of the crown and the embrasure line is

inversely proportional to the distance between

slot point and most prominent facial point of

crown in mid transverse plane.(Figure 6.3A) .

This means that if a tooth has less facial

prominence of crown it would have increased

bracket prominence (Figure 6.3B&C). The slot

point is the mid of the bracket slot in all three planes of space. For the ease of simplicity

since we are viewing the tooth from lateral

side so base of the slot instead of slot point

would be used in this text.

So in maxillary arch lateral incisor bracket

would be the most prominent bracket in mid

transverse plane. When such a bracket is placed

on the tooth a palatal force is expressed by the

flexible wire on this tooth as compared to

neighboring teeth which absorb reactionary

labial or buccal force because less prominent

brackets are placed on them . So eventually on

heavy wires maxillary lateral incisor crowns are

found to be less prominent than central incisors

and canine crowns while all the brackets slot

point or slot bases are at same level of

prominence .

In Andrew's prescription (table 6.2) of fully

programmed standard brackets, maxillary

Figure 6.2 Facial prominence of teeth in the arch.The distance between embrasure line and most prominentfacial point of each tooth is the prominence of the tooth. A. Average maxillary arch crown prominence. B. Averagemandibular arch crown prominence. These prominence

values are incorporated into the brackets by varying thedistance from base of slot to base of brackets.

Table 6.1.Crown prominence in maxillary and mandibular arch

Teeth Centralincisors

Lateralincisors

Canine 1st premolar 2

nd premolar 1

st Molar 2

nd Molar

Maxillary Arch 2.1mm 1.65mm 2.5mm 2.4mm 2.4mm 2.9mm 2.9mm

Mandibular arch 1.2mm 1.2mm 1.9mm 2.35mm 2.35mm 2.5mm 2.5mm

B

A

6CHAPTER


86



increased at the end of treatment.

Clinical implication of Key VI

Nothing is built within bracket prescription to

accommodate key VI because it is more related

with position of the brackets on the teeth.

Accomplishing this key is very important for a

good occlusal outcome. Andrew found that

nonorthodontic dentition has flat to slight curve

of spee and preposition of flat curve of spee was

given to accommodate natural tendency of

curve of spee to increase with age due to growth

of lower jaw and its growth rotation. Banding or

bonding the second molars also help in leveling

of curve of spee .Usually leveling 1mm of curve37

of spee require less than 1mm of space. A

description of curve of spee is given in the

figure 6.44.

Limitations of Andrew prescription

Large inventory

In Andrew system to deal with different types of

arch discrepancies there are 12 maxillary and 11

mandibular sets, which are combination of five

different types of brackets .These are

Figure 6.43. A. Improper tip of central incisors and lack of torque in lateral incisors. To compensate it canine was movedforward leaving poor contact point between canine and premolar. B. A case with good occlusal results and proper contact pointsdue to proper tip, torque, prominence and lack of rotation characteristics.

BB

B

A

A

A

A

Figure 6.44 A. increased curve of spee. If curve of spee is increased or deep, there would be less space for upper incisor.Occlusion would be disturbed both anteriorly and posteriorly. B. Reverse curve of spee. If the curve of spee is decreased or reversedin lower arch than there would be excessive space in the upper arch.

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S – Standard Brackets

T1 – Minimum Translation Brackets

T2 – Medium Translation Brackets

T3 – Maximum Translation Brackets

T4 – Maxillary Molar tubes or bands for Class

II&III

Andrew gave such a big inventory to make the

t rea tment more ind iv idua l ized . But

unfortunately this became one of the biggest

limitations of his prescription. Making so many

different types of brackets means that there is

need for more machinery, more space, more

work force and so more finances needed for themanufacturer. Also when there are so many

different types of brackets, more time and

education is needed for the orthodontist to get a

better understanding for making the right choice

in each case. So when there is no Magic formula

available, orthodontics will remain only for

professional orthodontists. This means loss of

valuable clientage for the manufacturers.

Unfortunately the problem in orthodontics is

that if the orthodontist is customizing treatment

answers. Do we need to accommodate wagon

wheel effect in class I incisor torque as it is

natural position of the incisors within the arch?

If wagon wheel effects occur due to anatomy of

area and our treatment mechanics, why not the

tip is decreased in the prescription in case of

class II incisor torque and increased in case of

class III incisor torque?

by bracket prescription or by wire bending he is

wasting his time but if the manufacturer is

customizing brackets it's an innovation and you

have to pay for that innovation.

For the orthodontist keeping a large inventory at

orthodontic office means there is need for more

financial resources and more office space. This

is obviously against the core rules of good office

financial management. So unfortunately the

very benefit of Andrew prescription to provide

individualized treatment to some extent became

the most limiting factor of its wide acceptance.

Tip and Torque

Both tip and torque values placed in Andrew prescription are slight different from Andrew

2original findings of normal occlusion .

Tip in Andrew Straight wire appliance and

actual tip from his study are given in table 6.12.

There is overall increased in tip in SWA as

compared to Andrew original findings. For

change in tip values it is generally presumed that

Andrew made the changes to accommodate

wagon wheel effects. There are some questions

in this regard that for the time being have no

Torque values were also changed by Andrew to

some extent than original norms (table

6.13).Overall there is decrease in torque values

in SWA as compared to original findings. After

going through Andrew work my understanding

is that Andrew changed the upper incisor torque

values to incorporate finding of his unpublished

100 cases cephalometric study. For example in

Table 6.12

119



original Andrew's norms the maxillary central

incisor class I torque was 6.11° while the lateral

incisor torque was 4.42°.In cephalometric study

Andrew found that there is always 4° difference

between maxillary central and lateral incisor

torque. So I presume that he changed the torque

of central to 7° and lateral to 3° to make that

study count. Other values were changed either

to incorporate clinical experience or to round off

values for ease of standardization.

Apart from this, Andrew also didn't take in

consideration various factors that affect the

expression of tip and torque especially the play

of the wire. This is because Andrew advocated

full dimension wires at the end of treatment forexpression of entire builtin tip and torque.

Because of their increased stiffness use of full

dimension wires have been abandoned and so

the problem started with expression of the

prescription.

Counter-rotation

Andrew incorporation of counter rotation into

the slot was also not appreciated by many.

Though effective during space closure but if theorthodontist remain on a heavier wire for long

time using effective ligation of wire to

consolidate tooth position or torque correction

after space closure the teeth having counter

rotation brackets will become rotated due to

expression of prescription .

So Andrew prescription presents a dilemma for

clinician in extraction cases. Moving to heavier

wire for better tip and torque expression as

Andrew didn't accommodated wire play in his

prescription but such wire will cause counter

rotation expression. Many clinicians who

favors counter rotation in brackets for

extraction cases and also have included counter

rotation in their own prescription advocate that

as relapse is inevitable so the rotation is part of

over correction and it will eventually be

relapsed during the settling phase. But the

practical problem a young orthodontist face

today is that he has to display his finished case

in exam and complete the settling phase with

elastics or wire bending than going on natural

settling with retainers. It is difficult to settle

teeth into occlusion when they are rotated.Correction of rotation will leave space in the

arch and there are many different retainers of

modern day such as fix retainers and vacuum

formed retainers that don't allow settling to the

extent as Hawley retainers do.

So orthodontists are left with two choices when

using counter rotation brackets at the end of

treatment. Replace bracket with standard

brackets or resort to wire bending.

Limitations in Mechanics

As expression of bracket prescription depend

upon what mechanics one uses, many clinicians

who later made their own prescription pointed

out some mechanics flaws present in Andrew

philosophy for case treatment. These were

1) Anchorage loss

Table 6.13

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As tip built into Andrew appliance was more

than what Andrew found in his original

research so this increased tip put strain on

posterior anchorage and also cause anterior

anchorage loss at the initial stages of

treatment. Anchorage control was alsodifficult in extraction case.

2) Leveling Curve of Spee

Many clinicians also didn't agree with

Andrew philosophy of leveling curve of spee

with compensatory curves in wires in

maxillary arch and reverse curves in wire in

mandibular arch.

3) Roller coaster effects

In early years of SWA class II elastics were

used for sliding mechanics. In order to

overcome friction heavy forces were used.

Increased anterior tip, vertical component of

elastics and heavy forces resulted in

deepening of anterior bite and opening of

lateral bite. This effect was called Roller

Coaster Effect (Figure 6.45).

4) Root parallelism

Andrew measured tip values by using long

axis or facial axis of clinical crown and not

the whole tooth. There is always some degree

32of variation between long axis of clinical

crown and long axis of the tooth. Placing the

bracket just by keeping in mind the long axis

of clinical crown will result in poor root

parallelism in many cases. Also due to

increase tip built into Andrew prescriptionthere are chance of root approximation of

teeth especially between maxillary canines

and premolars.

5) Bracket Height

Andrew advocated bracket placement at mid

of long axis or facial axis of clinical crown

also called LA point(long axis point) or FA

point(facial axis point). Judging the FA point

or LA point on a tooth was a matter of clinicalexperience. Some clinicians

3, 38didn't agree

with validity of placing bracket at the FA

point to get an ideal occlusion while others39, 40

advocated that there are greater chances of

error in placing bracket on FA point and gave

fixed distance from incisor edge and

suggested using special gauges for bracket

placement. Effects of change in height on

bracket prescription have been discussed

before.

Because of these limitations different types of

bracket prescription were put forward with

time. Whether these new bracket prescriptions

solved any practical limitation of Andrew

prescription is still debatable but there is a

general consensus that they solved the problem

of manufacturers and general dentists in the

form of “A Single Fairytale Bracket Set for All

Types of Malocclusion”.

Different Bracket prescriptions

With time so many clinicians put forward their

own prescriptions of brackets .For effective use

of these prescriptions many of them also

advocated their own treatment mechanics and

bracket position on teeth. Even some clinician

went to the extent to recommend certain

commercial brands of wires for effective

Figure 6.45 Roller coaster effects and anterior deep biteand lateral open bite.

121



diminution of force.

III. Leveling of curve of spee to some extent by

placing anterior brackets more incisal.

IV. More torque in anterior brackets to

accommodate torque loss by wire play.

V. Super torque brackets for rapid correction of

torque in class II div2 cases.

VI. Roth proposed a new archform called Tru-

Arch to be used with his prescription. Roth

advocated selection of archwire is important

as it effects the rotational position of teeth.Wider the archform more positive torque

would be expressed and vice versa. Roth

archform was most prominent and wide at

mesiobuccal cusp of the first molars.

VII. Different translation philosophy.

According to Roth tipping of the teeth to some

extent is accepted on round wires.

VIII. Many auxiliary features were added to

brackets such as double and triple tubes,

addition of hooks for ease of mechanics.

How Roth Made this Prescription?

Dr. Andrew in one of his articles42 commented

on origin of Roth prescription. According to

Andrew, Dr. Roth found that a high percentage

of his cases can be treated by using Andrews'

class III incisor torque brackets for maxillary

arch and class I incisor torque brackets for

mandibular arch. For buccal segment Roth used

Series 1-C and Series II-Classic. Where series

1-C was given in all 1st premolar extraction

cases where both maxillary and mandibular

canines are given maximum translation series

brackets and both arches 2nd

premolars are given

minimum translation series brackets while

molars are given standard SWA. Series II-

Classic brackets were used in case of extraction

of maxillary 1st and mandibular 2

nd premolars

because of class II molar relationship. In this

series maxillary canines and lower posterior

Table 6.15 Mandibular arch values of different prescriptions

Mandibular

Arch Centralincisor

Lateralincisor

Canine 1st Premolar

2nd Premolar

1st Molar 2nd Molar

Torque° Tip° Torque° Tip° Torque° Tip° Torque° Tip° Torque° Tip° Torque° Tip° Offset° Torque° Tip ° offset

Alexander -5 +2 +5 +6 – 7 +6 –7 0 –9 0 –10 0 0 0 0 5

Begg 0 0 0 0 0 0 0 0 0 0 0 0 6 0 0 6

Burstone –1 0 –1 0 – 11 + 6 –17 0 –22 0 – 27 0 5 –27 +2 6

Damon

(standard

torque)

-3 2 -3 +4 +7 +5 -12 +4 -17 +4 -28 +2 2 -10 0 5

Hasund 0 0 0 +5 0 +5 –10 +2 –15 +2 -22 +4 0 – 25 +2 6

Hilgers –1 0 –1 0 +7 +6 –11 0 –17 0 –25 0 7 –25 0 6

Ricketts

®

–IV.

Dimension

0 0 0 0 +7 +5 -7ex0 n-ex

0° -7 ex-14 n-ex

0 –22° –5 12 –27 0 16

Ricketts®

Standard

0 0 0 0 +7 +5 0 0 0 0 0 0 0 0 0 0

Standard

Edgewise

0 0 0 0 0° 0 0 0 0 0 0 0 0 0 0 0

Tweed 0 0 0 0 0 0 0 0 0 0 0 0 0/6 0 0 0/6

123



are given maximum translation series brackets

and lower canine and upper posterior are given

minimum translation series brackets.

Roth prescription is given in table 6.16.

These comments by Andrew about Roth prescription were made in 1976 and in the same

43year Roth wrote an article about his 5 year

practice changing experience with Andrew

prescription. Unfortunately he didn't reveal

anything about his specific selection of brackets3

from Andrew's work. It was in 1987, that Roth

published his prescription and given

justification for it. That prescription is far

different from Andrew's comments. The only

comment true is about maxillary andmandibular incisor tip and torque. A personal

review of literature by this author couldn't find a

prescription by name of Roth that matches

Andrew's comments. The first published Roth

prescription is given in table 6.16.

An evaluation of origin of this prescription is

given.

Maxillary Arch.

Where MR=Mesial Rotation to counter distal translation. DR= Distal rotation to counter mesial

translation. P1 = 1st Premolar P2 =2

nd Premolar , Class II= Molar Class II in cases where

only upper 1st or 2

nd premolars are extracted .Reference for above Table 3, 40

.

Canines

The maxillary canine tip is taken from

minimum translation series brackets made for

distal translation. Canine torque was Roth

personal calculation of torque to accommodate

wire play. Canine counter rotation feature wasalso taken from Andrew distal translation group

in minimum translation series brackets.

Premolars

st ndBoth 1 and 2 premolar tip was taken from

minimum translation series brackets requiring

mesial translation. Premolar torque was taken

from Andrew standard SWA. Counter rotation

feature was taken from minimum translation

series brackets for distal translation.

Molars

st ndBoth 1 and 2 maxillary tip was selected from

Andrew Class II molar tip. Torque of molars

was selected from Andrew medium translation

series brackets. Counter rotation values for

molars were taken from medium translation

series for mesial translation.

Table 6.16. Roth Prescription

Teeth Central

incisors

Lateral

incisors

Canine 1st & 2nd Premolar 1st &2nd Molar

Torque

°

Tip

°

Torque

°

Tip

°

Torque

°

Tip° Rotatio

n°

Torque

°

Tip

°

Rotation

°

Tip

°

Torq

ue°

Rotation°

Maxillary

Arch

+12 +5 +8 +9 -2 +13 2MR -7 0 2 MR 0 -14 14DR/0°

Class II

Mandibul

ar arch

-1 +2 -1 +2 -11 +7 2 DR -17

P1&

-22

P2

-1 4DR -1 -30 4DR

6CHAPTER


124



Controversy

In maxillary arch both canine and premolars

brackets have minimum translation features

builtin. If one tooth need to be minimally

translated in extraction space in most of the

cases than the other tooth need to be maximally

translated to close the extraction space.

Premolars have counter rotation feature for

distal translation. It's a common finding that in

most of our cases premolars needed to be

translated mesially than distally. Also premolar

counter rotation feature don't correlate wellnd

with molar except in 2 premolar extraction

cases where molar need mesial translation and

1st premolar need distal traction.

The molar tip is meant for class II relationship

while offset is meant for class I molar

relationship.

Mandibular Arch

Canines

Canine tip is taken from minimum translation

series brackets for mesial translation while

torque is taken from Andrew standard SWA.Counter rotation feature for canine is taken

from minimum translation series for mesial

translation.

Premolars

Premolars tip correlate with Andrew medium

translation series brackets. Torque values

remain similar to standard SWA while counter

rotation feature values are from medium

translation series for mesial translation.

Molars

Molars have tip of medium translation seriesst

for mesial translation. 1 mandibular molar

torque remain same as that of standard SWAnd st

while 2 molar torque was made equal to 1

molar. Counter rotation feature were also taken

from medium translation series brackets for

mesial translation.

Controversy

In mandibular arch canine is given minimum

translation series counter rotation feature and

tip values while molars and premolars havemedium translation series values. Second

stmolar torque was made equal to 1 molar.

Giving less torque on second molar increase

their chances of coming in cross bite as it's and

common finding that 2 molars are usuallyst

present slightly buccally as compared to 1

molar in finished cases using Roth prescription.

Roth Justification for his prescription

3Roth while giving his prescription gave some

justification for the specific selection.

Maxillary Arch

Roth3 justified his prescription by explaining

that 5° extra torque was added to maxillary

incisors keeping is line with his treatment

p h i l o s o p h y o f o v e r c o r r e c t i o n a n d

accommodating torque loss by wire play. So

without moving to full dimension wires the

clinician can attain natural inclination of

incisors.

For canines, Roth used -2° torque which was -

5° less than Andrew prescription. This was

done to avoid reactionary effect of building

more positive torque into the incisors brackets.

This is explained in the figure 6.46. The final

torque of canine would be -7° due to

reactionary forces from the wire and because of

wire play. If no wire play is present the finaltorque of the canine would be -2°.

Also canine tip was increased by +2° to

accommodate tip loss in extraction cases as

distal translation of canine take place and it is

also helpful to get better canine guidance.

Canines was also given 2° rotation to mesial

so that when it is translated distal, mesial

builtin rotation compensate the effect of distal

125



rotation that occur during distal translation of canine.

Premolar torque was kept the same while the tip

was decreased. Though there was no

justification given for using minimum

translation angulation in both premolars nor

does there is any logical basis of decreasing tip

after giving 2° mesial offset for counter

rotation. This decreased tip can accommodate

increased tip on canine but the roots of these

teeth come close to each other at end oftreatment. Also 2° mesial rotation was added to

premolar brackets. The justification was that

this was done to counter the of effect distal

traction of these teeth. As Roth favored

headgears in his mechanotherapy this addition

seems logical.

st ndOn 1 and 2 molars buccal root torque was

increased from -9° to -14°.The increased torque

BB C

Figure 6.46 A .A rectangular wire passed through maxillary incisors and canine brackets. The slots opening of the maxillaryincisors is facing downward causing the wire to rotate clockwise on exiting the lateral incisor bracket. This clockwise rotated wirewhen passes through canine bracket whose slot opening is facing upward will cause the canine bracket to rotate clockwise whilecanine bracket slot will cause the wire and so the incisor brackets to rotate counterclockwise. So positive torque would beexpressed on incisors and negative torque would be expressed on canine. If the incisors have more positive torque, than reactionaryforces of wire leaving from incisors will cause more negative torque on canine. This only happen when wire play is present. If nowire play is present all the torque built within the bracket would be expressed. B. Wire exiting lateral incisor in a clockwise fashion.C. Wire engaging canine bracket clockwise at an angle thus negative torque expression in canine.

Figure 6.47 According to Roth -14° torque should begiven to maxillary molar to counter the effect of palatal cusphanging during translation. A. Palatal cusp hanging inmaxillary molar after translation.B. No cusp hanging.

BB

AA

AA

6CHAPTER


126



7 C

H A P T E R

Placement of orthodontic brackets

In this Chapter

Mesiodistal position of brackets

Checking mesiodistal position of thebrackets

Modifications in mesiodistal position ofthe bracket

Axial or long axis position of the brackets

Importance of axial position of brackets

Checking axial position of brackets

Modifications in axial position ofbrackets

Vertical position of brackets

Modifications in Vertical position of thebrackets

Importance of vertical position of

bracketsBracket positioning gauges

Parts of gauges

Position of the gauge during bracketplacement

Bracket placement by wire guidance

Position of clinician during bracketsplacement

Prescriptions in preadjusted edgewise brackets

are built after taking prescription values from a

certain point or area on labial surface of the

tooth. The prescription built into the bracketwill work best if the brackets are placed at that

specific area. Mostly that specific area where

the brackets needed to be placed is also

pinpointed by the inventor of the prescription.

During orthodontic bonding of preadjusted

brackets the orthodontist must place brackets

accurately in vertical, mesiodistal and axial

planes as advocated for that prescription

or based on his clinical experience. These

accurately placed brackets will give better

control on three dimension position of the

teeth during treatment. An accurately placed

bracket will also result in better expression ofits builtin prescription and orthodontist will

need less wire bending and complex

mechanics during the course of treatment.

Mesiodistal position of brackets

It is a general saying in orthodontics that

brackets should be placed at mesiodistal center

of the teeth. This statement is partially correct as

this rule can't be applied to all the teeth. A more

153



clear description for right mesiodistal position1

of brackets was given by Andrew that brackets

should ideally be placed at the mid

developmental ridge of the teeth. The correct

mesiodistal position of brackets on different

teeth is given as under.

Maxillary and mandibular incisors

Bracket should ideally be placed at

mesiodistal center of maxillary and

mandibular incisors. The mid developmental

ridge of these teeth is also present at their

mesiodistal center of the labial surface (Figure

7.1).

Maxillary and mandibular Canines

Placing brackets at the mesiodistal center of the

canines will result in contact point error andslight rotation of the teeth as the mid

developmental ridge of upper and lower canines

lies slightly mesial to the mesiodistal center of

the teeth and is more mesial in case of lower

canines. So bracket is placed slightly off center

and toward mesial, in case of canines (Figure

7.2).

Mandibular Premolars2

Roth purposed that premolars brackets should

be placed at area of maximum convexity which

is usually the mesiodistal center of the teeth and

mid developmental ridge also lies in this area.

Sometimes the area of maximum convexity lies

slightly mesial to the mesiodistal center but

degree of mesial deviation is less than that of

canines. The difference between bracket

placement on premolars and anterior teeth is presence of a lingual cusp on premolars which

must be taken into consideration while placing

the brackets. In mandibular premolars the

buccal and lingual cusps lies at the same level in

the mesiodistal perspective. So when placing

lower premolars brackets the scribe line of the

bracket should coincide with line connecting

the buccal and lingual cusps (Figure 7.3).

Figure 7.1 Vertical lines showing mesiodistal center ofthe upper and lower incisors. Brackets should be placed atthe recommended height on this line.

Figure 7.2 The vertical lines on maxillary and mandibularcanines indicate the mid developmental ridge of the caninesand ideally the middle of the brackets should coincide withthis line.

CHAPTER 7CHAPTER

P l a c e m e n t o f o r t h o d o

n t i c b r a c k e t s

154



8 C

H A P T E R

Bonding in Orthodontics In this Chapter

Tooth Cleaning

Enamel Roughening or acid Etching

Sealing the etched enamel surface

Bonding

Bonding in special circumstances

Indirect bonding

Historically orthodontic brackets were soldered

to bands and eventually banded to teeth. As bands need space between the contact points at

time of their placement and leave spaces

between teeth at end of treatment so they were

not a preferred method.

With the introduction of acid etching by1

Buonocore in 1955 banding of teeth was

eventually abandoned with time and is now only

used on molars in cases requiring special

mechanics like headgears. Extensive detailsabout bonding are given in almost all the text

books of orthodontics so only a brief review on

this topic would be given here.

Bonding of brackets can be done either directly

or indirectly. Steps in direct bonding of bracket

are given.

1. Tooth cleaning

2. Enamel roughening of labial or lingual

surface of tooth by acid etching

3. Sealing of etched surface

4. Bonding

1) Tooth Cleaning

This step is only done in patients in whom

there is plaque or thick pellicle layer over the

enamel surface at the time of bonding.

If only pellicle is present then pumicing of

teeth alone is sufficient but if plaque or

calculus is also present over the enamel

surface then scaling is done which is

followed by pumicing (Figure 8.1).

189



2) Enamel Roughening or acid Etching

Enamel roughening or acid etching is done to

create retention areas for the adhesive on the

enamel surface.

Moisture control is important during this

step and rest of the steps that follows.Good moisture control is provided by using

cheek/lip retractors and high volume

section. This arrangement of moisture

control is usually sufficient in majority of

the cases but in some cases where patients

have increased salivary flow, special

gadgets are available that combine lip/

cheek retractors, saliva ejectors and tongue

guards (Figure 8.2). Cotton rolls are also

used to increase moisture control. Someclinician also uses antisialogogue like

atropine sulphate to create a dry field for

brackets bonding. Antisialogogues can be

used on patients having excessive salivary

flow but evidence8 doesn't support their

routine use during orthodontic bonding.

Before going for enamel conditioning

enamel surface should be dried with oil free

air. Enamel conditioning is conventionally

done with 35 - 37% phosphoric acid. Enamel

roughening by sandblasting has also been

proposed but sandblasted enamel yield lower9-13

bond strength than acid etched enamel.

Sandblasting first followed by conventional

etching have also been proposed but bond

strength of brackets with this combination14, 15

technique is controversial than doing

conventional acid etching alone. Lasers have16-19

also been advocated for enamel etching20

either alone or in combination with acid

etching. But due to high cost of lasers and

more safer application of conventional

etching the use of laser for enamel roughing

is still a novel approach in orthodontics.

In enamel etching with 37% phosphoric acid

the acid is available in both liquid and gel

form. The liquid form of the acid has

Figure 8.1 Pumicing teeth with a polishing paste and pumice powder.

Figure 8.2 A Nola dry field system combining all thenecessary gadgets for good moisture control during enamelconditioning. This system is especially helpful in indirect

bonding.

Clinical Notes

2-4Pumicing before etching is controversial

if conventional etching is done but clinician5-7

should do pumicing if self-etching primer

is used.

B

A

CHAPTER

B o n d i n g i n

O r t h o d o n t i c s

8

190



10 C

H A P T E R

Adhesive Remnants Removal

In this Chapter

Hand instrumentation for adhesive

removal Adhesive removing pliers

Ligature wire cutters

Hand Scalers

Rotatory instruments

Burs

Carbide burs

Diamond burs

Steel burs

Brown and green stones

Composite burs

Discs

Finishing and polishing auxiliaries

Ultrasonic scalers

Sandblasting or air abrasion

Adhesive remnants removal by Lasers

After orthodontic brackets removal, adhesive

remnants needed to be removed from the tooth

so that enamel can be returned to its

pretreatment condition. These residual adhesive

if remained attached to the teeth will be a potential plaque retentive area and may get

discolored with time.

The amount of these adhesive remnants

depends upon the type of bond failure. If bond

failure during debonding occurs at bracket

adhesive interference, more adhesive needed to

be removed as compared to a bond failure at

enamel adhesive interference (Figure 10.1).

Removal of these adhesive remnants should be

done without causing any damage to enamel.

Figure 10.1 Adhesive remnants on the tooth afterdebonding. Bond failure occur at the bracket adhesiveinterference. Such bond failure require more time to cleanadhesive from the tooth enamel.

239



11 C

H A P T E R

Recycling of orthodontic brackets In this Chapter

Introduction

Recycling of orthodontic brackets

Ultrasonic Cleaning

Electropolishing

Adhesion Enhancement

Silane coupling Agents

Adhesion Boosters

Rotatory instruments

Flame MethodBuchman modiifed flame method

Modified Buchman method ,The AcidBath

Limitations of flame method

Lew and Djeng Method

Chemical Method

Sandblasting

Laser Recycling

Introduction

Recycling or reconditioning are different terms

used for reusing orthodontic brackets which

were once bonded in clinical practice and were

latter debonded accidently by the patient or

intentionally by the clinician. 5% to 7% of

brackets bonded with light cured or chemical-1, 2

cured composite resins debond in clinical

practice under different circumstances. Some of

these circumstances are as follow.

1. Bracket debonded by patients

This usually occurs while masticating hard

food, aggressive tooth brushing or by traumatic

forces especially in children while playing

sports. Some externally motivated patients also

intentionally debond the brackets to show their

unwillingness towards treatment.

255



Abfraction, 229Access bevel, 82

Accessary slots, 61,65,77,79

Accessory tube, 82

Acetone, 222,264

Active ligatures, 134,235

Active self ligating brackets,72,73,264

Adhesion boosters, 255,260,261,273

Adhesion enhancement, 255,257,260

Adhesive precoated brackets,193,196

Adhesive remnants,210,261,265,268

Adhesive removing plier 203,214,240AISI 21,24,25

All Bond 2, 261

All Bond 3, 261

Alumina Brackets,36

Amelogenesis imperfect,229

Andrew plane,165

Antirotation,98,116

Antisialagogues,190

Aperture diameter,45,46

ASTM,27

Attrition,33,34,160,161,178,229Austenitic stainless steel,24,25,32,263

Auxiliary features,77,123,

Auxiliary procedures,257

Auxiliary spring ,6,65,67,

Axial position,114,160,161,184,194

A

Band removing plier ,214,241

Bandeau appliance,1,2,3

Base method, 19,203,205,207.209,257

Begg appliance,5,6,61,172

Big Jane machine,272

Bis GMA ,227,228,235,260

Black triangle,94,161,162,164

Bleaching ,195

Bonding base shape ,57

Bracket base surface area,56,57,59,266

Bracket identification

B

Bracket identification marks ,58,80

Bracket prominence,63,86,87,113,

Bracket removing plier ,210,215,249

Bracket sitting area,171

Bracket stem,18,100,208,212,259,

Brazing,13-21,38,42,209,260,

Bristle brush,240,249

Broussard bracket,8

Brown and green stones,243,246

Brown part,16

Buccal groove,88,93,97,127,128,133

Bunsen flame,262

Calcium phosphate ceramics,36-38

Canine tie backs ,134

Carbide burs,195,227,243-253

Casting,14,,15,18,23,27,43,47,51.260

Central fossa,84

Ceramic injection molding ,18,36

Ceramic reinforced plastic,216,217

Chamfered slot walls,70,72

Chemical Retention ,50-57,218,220

Chromium oxide,22,26,28,Chromophores,231

CO2 laser 234,235,252,270

Cobalt Chromium Brackets,27,50,259

Cold working,20,23

Collapsible base ,219,220,222

Composite burs , 243,246,247

Composite plastic brackets ,32,216

Composite resin ,56,194,223,227,241

Compound contoured base,57,59,104

Computer numerated milling ,16

Connectors,94,160,161,164

Contact angle ,30,46,66,69,102

Contact points,117,118,189,256

Contact sports,256

Continuous mode ,234

Convenience features ,79-82

Corrosion resistance,17,19,21,24-

28,111,260

Counter buccolingual tip,102

Counter rotation ,116,117, 120,122 ,124-

126,130,131,157

C

CP titanium,28-30

Cracked teeth ,209

Crown Angulation ,92-94

Crown inclination,99

Crown morphology,136,161

Crown remover,226

Curve of Spee,117, 118,121,123,129, 132,

165,166, 173

Debonding plier,205,206,208,210-230

Debracketing, 203

Deligation saddle,82

Dentinogenesis imperfect,194,209, 226, 256

Differential anchorage ,6,10

Direct bonding ,169,171,189,256

Distal offset ,88-90,134,137

Distal translation ,95,96,117,124-126

Double mesh base,42,44,269

Dougherty gauges,181

Duplex stainless steel,26

Dust confinement chamber,266

Duplex stainless steel,26

Dust confinement chamber,266

D

E arch,3,4

Edge bevel,107,108

Edgewise appliance,7,13,64,104

Elastic ligatures,72,82

Elastic modules tie backs,132,134

Electrolytic solution ,259

Electromagnetic spectrum,230,231, 233, 234

Electropolishing

Electrothermal debonder , 229

Embrasure,91,92,94,155,160,161,164

Embrasure line,85-90

Enhance polisher,249

Er,Cr:YSGG lasers ,270

Er:YAGlasers,195,233,252,270,271

Erosion ,229

Esmadent,259,271,272

Ethanol ,53,222

Excimer lasers ,232,233

E

(I)



Nd:YAG,35,48,233,252

Nickel allergy,19,20,22,28,30,31,33

Non vital teeth,220,221

Notching,205,223

N

FA point,58,121,165,171,FACC,92,93,97,99,105,165

Facial point ,85-87

Facial prominence ,85,86,88,90

FDA,257

Feedstock,16

Ferritic stainless steel,25

Fiber reinforced ,246,247

Filling adhesive ,194

First order bend,61,62,163

Flame gun ,229,262,264

Flame method ,19,48,50,70,257,258, 262-265,270,273

Flamepyrolytic method,260

Flash ,22,168,193,196,218,222-227,

242,266

Foil mesh base ,42,43,47

Free play,107

Frequency,224,231,251,271

Friction resistance,16-18,27,29,31,32,

37,70-73

Gated pulse mode ,234

Gauze or woven mesh base,42,43,46, 50Gingival hyperplasia,77,209

Gold plated carbide bur,261

Green part ,16

Hand scaler,240,243

Hard tissue lasers,231

Headgear tube,82

HEMA,227,228

Horizontal slot,5,10,65,80

Howe plier,208,212

Hybrid copolymer,32

Hydrofluoric acid,195Implants,28,34,161,162

Impulse debonding,205,226,227

In and out bends,8,9

Indirect bonding,169,190,195,198,256

Integral bases,47

Interarch relationship,84

Isopropyl alcohol,264

Kinetic energy,227

Kobayashi hook,78

KrF Lasers,270

FLA point,121,165LACC,92,93,99,105,159,165

Laminated mesh base,42

Lang brackets,8

Laser structured bases,48,50,54,267,268

LED curing light,192,195,199

Lewis brackets,7,8

Lift off debonding plier,199,212,213

Ligature cutter,82,210,211,221,242

Light wire appliance,6,9,10,172

Line pressure,47,197,260,263,266-269

Lingual brackets,10,111,214,215Long axis position,93,158,160,161,184

Luting adhesive,50,53,194

LMicroetched bases,42

Microleakage,192

Microretention,47,48,195,240

Mid-developmental ridge,92,93,154,156,158,165

Milling,14-18,20,21,37,47,194

Mini mesh base,42

Minimum Translation series,95,96,102,123-125

Moisture insensitive primer,192

Molar offset,88,90-93,98,127

Moment arm,66,69

Monobond plus,261

Monocrystalline brackets,35,37,38,55,

232,233,235,265

Occlusal plane,92,93,97-

99,105,106,112,117,127,129,133,135,

136,162,166,182

Open area percentage,46,47

Optimesh base,42

Ormesh base,42

Ortho bonding,271,272

Ortho Solo,261

Orthotronics,271,272

OMagnetostrictive scaler,224,240

Manufacturer tolerance,99,108

Marginal ridges,166-173

Martensitic stainless steel,25,26

Maximum translation series,95,96,102,123,124

Meccaca Monkey,228

Mechanical Retention,42,46-48,50-

52,54,55,218

Mechanotherapy,107,109,126,130

Medium translation,95,96,102,119,124,125,137

Mesh diameter,44,45

Mesh gauge,44

Mesh number,44-46,50,267

Mesh type bases,48,50

Mesial offset,90,122,126

Mesial translation,95,96,124,125

Mesiobuccal cusp,84,88,91,92,97,98,123,127,156

Mesiobuccal groove,88,91,92

Mesiodens,161,162

Mesiodistal Crown tip,92

Mesiodistal position,153,154,156,157,183-186,194

Mesiolingual cusp,84,91,92,127

Metal injection molding,14-18,27,47

Metal sintered bases,48

Metallic luster,263

Micro mesh base,42

M

Passive self ligating

brackets,10,72,73,109,264

Pellicle,189

Peppermint oil,222

Perforated bases,42,43

Phosphoric acid,190,195,240

Photoablation,232,235

Photoetched bases,42,47

Photon,231

Piezoelectric scaler,224,240

P

(II)



Pin and tube appliance,4

Plasma arc curing light,192

Plasma coated brackets,48,50

Plastic Brackets,14,19,31-34,51-53,68-71

Plastic injection molding,19,31

Plastic primer,51

PoGo polisher,247,250,253

Polyacrylic acid,191,222

Polycrystalline brackets,18,34-38,55,232-235

Polymer mesh base,51,54

Polyoxymethylene Brackets,31,32

Polyurethane brackets,31,32

Porcelain veneers,195

Power arms,77-79,81,94,95,99

Preadjusted edgewise

appliance,8,9,64,83,102,153,158

Precious metal brackets,21,30,31,51

Precipitation hardening,25,26

Prescription,9,10,15,22-24,61-63,67, 69,

83,87,90-96

Primer 31,32,51.190,191,199,260, 261, 270

Protective goggles ,194,195,222

Pulse mode ,231,234

Pumicing,189,190,199240,243,249-253

Separators ,199

Shape of brackets,80

Siamese bracket,7

Side cutter,210,213,223

Silane coupling agent,50-

54,195,260,261,264,269

Silica coating,52,261,264,269,

Silica lined slot,70

Silicon tray,196,197

Single mesh base,42,44,269

Single slot brackets,7,67

Sintering,16-18,26,35,36

Slip planes,218

Slot base,71,72,86,87,105,

110,116,117,208

Slot creep,32

Slot point,58,77,86,87,94,95,116

Slot rotation,116

So flex discs,247,248,253

Sodium bicarbonate,259,272

Soft tissue lasers,231,233,234

Soldered,2,4,7,13,162,189,256

Speed brackets,166

Standard brackets,61,69,95,100,

102,119,120,129

Steel burs,139,243

Steel ligatures,34,72,109

Straight wire appliance,8,9,58,84,94,

100,102,117,119,162

Super Austenitic Stainless steel,25

Super Ferritic stainless steel,25

Super pulse mode,234

Super snap discs,247,248

Super torque,123,127,128,131,136,141

Supermesh base,44,50

Thermal ablation ,232,235

Thermal softening ,232,234,235

Third order bends,63

Tip edge,10,65,67,79

Tip edge plus brackets 10 65 67

T

Recycling ,110,198,206,208,209,215,227,251,255

Replaceable tips,221

Resin modified Glass ionomer cement,56,194

Ribbon arch appliance,4-6,61

Roller coaster effects,34,121

Rotatory instruments,240,243,252,255,257,261

Roth extra torque,131

Roth Surgical,129,130

R

Ultra pulse mode ,234

Ultrasonic cleaning ,257,258,262,264-266,273

Ultrasonic debonding ,22,224-227

Ultraviolet light ,233

Universal brackets ,6,7

U

Van der Waal forces ,227

Vertical groove ,93

Vertical Mid Scribe line,79

Vertical slot ,5,7,8,61,65,67,79,80,219Vickers hardness,17,23,109

V

SAE,21

Sandblaster,251,252,266,267

Scaling,189,224,245,250,

Second order bends,62

S

Torque in the Base,58,100

Torque in the face,58,59

Torque play,15,72,107,108,110

Torque zone,112

Torqueing springs ,63,79

Tribochemical method ,260,261

True twin brackets ,68,69

Tungsten carbide bur,244-253,261

Twin bracket,7,35,56,68,69,208

Twin wire appliance,6,7

Wagon wheel effects,114,115,119,132,

134-136

Wavelength ,192,230-235,270

Weingart plier,212,219,220

Wick stick,167,181

Wing method,19,205-210,212,214-217,

219,257,260

Wire bevel,108

Wire diameter ,44-46,267

Wire guidance,110,143,163,183,184

W

Z

Documents

bonding brackets.pdf