Essentials of orthodontics

• Orthodontics in India 5 • Evolution of Orthodontic Appliances 5General Principles and Concepts 9 • Definitions 9 • Factors Affecting Physical Growth 10 • Concepts of Growth 11 • Types

Essentials of ORTHODONTICS

Professor and HeadDepartment of OrthodonticsChhattisgarh Dental College and Research Institute

Rajnandgaon, Chhattisgarh, India

Foreword

A Venkatesan

JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD

New Delhi • London • Philadelphia • Panama

®

www.ajlobby.com

Jaypee Brothers Medical Publishers (P) Ltd.

Headquarters

Jaypee Brothers Medical Publishers (P) Ltd.

4838/24, Ansari Road, Daryaganj

New Delhi 110 002, India

© 2013, Jaypee Brothers Medical Publishers

All rights reserved No part of this book may be reproduced in any form or by any means without the prior permission of the publisher.

Inquiries for bulk sales may be solicited at: jaypee@jaypeebrothers.com

This book has been published in good faith that the contents provided by the author contained herein are original, and is intended for educational purposes only While every effort is made to ensure accuracy of information, the publisher and the author specifically disclaim any damage, liability, or loss incurred, directly or indirectly, from the use or application of any

of the contents of this work If not specifically stated, all figures and tables are courtesy of the author Where appropriate, the readers should consult with a specialist or contact the manufacturer of the drug or device.

Essentials of Orthodontics

First Edition: 2013

ISBN: 978-93-5090-329-2

Printed at

Jaypee Brothers Medical Publishers (P) Ltd.

17/1-B, Babar Road, Block-B, Shaymali

Jaypee-Highlights Medical Publishers Inc.

City of Knowledge, Bld 237, Clayton Panama City, Panama

Phone: +507-301-0496 Fax: +507-301-0499

Email: joe.rusko@jaypeebrothers.com

www.ajlobby.com

Dedicated to

My father

Mr K Sivaraj

www.ajlobby.com

In recent years, orthodontics has become one of the most vital subjects for study in the understanding of general dentistry Due to varied reasons, the subject has remained largely unexplored among general practitioners and undergraduate students There has been a huge hurdle for the general practitioners and undergraduates, who want to explore further in the field of orthodontics due to unavailability of compact text, highlighting all the essentials in orthodontics.

I find, Dr Aravind Sivaraj has made an honest attempt to fill up this lacuna in elaborating all the essentials of practical and clinical orthodontics

What makes the book unique and hence worth possessing is its format and a large number

of illustrations and diagrams make the understanding of the subject easy It is evident that a lot

of meticulous thinking and hard work have gone into this work and the labor would be fruitful

if the people for whom it is intended enjoy the book

The interest and the efforts of Dr Aravind Sivaraj are highly commendable and the book should stand as an example to other young teachers to emulate

I am sure that the book would not only be accepted and appreciated by all, but also many more editions of it, would be published with regular upgradation of the material contained in it

A Venkatesan MDS

Former Principal, Professor and Head

Department of Orthodontics Tamil Nadu Government Dental College and Hospital

Chennai, Tamil Nadu, India

Foreword

www.ajlobby.com

Essentials of Orthodontics is written in clear and simple language useful for the under graduates

in dentistry, general practitioners and as a quick reference guide for the postgraduates in orthodontics

This book is edited from various textbooks, study materials and manuals in orthodontics The purpose of the book is to educate the students with clear thoughts on the subject with emphasis

on the deep understanding of the concepts and theories in orthodontics

The text is written for rapid and easy uptake, with only a few classical illustrations and a handful of carefully chosen references Many topics are well covered in other texts, and do not need a lengthy description, but where clinical precision or a new concept is involved, a full explanation is provided

The book is designed for the dental students, orthodontic residents and general dentists to understand the basic concepts and essential procedures regarding the diagnosis, treatment planning and treatment of patients, who have relatively simple malocclusion problems and to consult the specialist in case of complex problems

Readers will essentially learn about the mechanics of how appliances move teeth, the different types of appliances, and the latest orthodontic materials in the market A much-needed text for the dental students and also an excellent resource for dentists, who want to expand their practice The book is not intended to compete with the major texts on the theory and techniques that form the basis of contemporary orthodontic teaching and practice However, the book will

be a valuable and welcome addition to the existing texts in orthodontics

Orthodontics is constantly changing and has become a dynamic field in dentistry and medicine Rapid advancement in the orthodontic technology and techniques has transformed the field into the first and best specialty in dentistry Every possible step has been taken to prevent any errors and mistakes in the subject; any such occurrence is highly unintended and unfortunate Comments and suggestions are highly appreciated

Aravind Sivaraj Preface

www.ajlobby.com

I believe that orthodontics is one of the finest professions, as it combines the best of both the science and art of dentistry The greatest appreciation, we can demonstrate to our profession is

to impart and pass on knowledge and expertise to students and fellow colleagues

First of all, I wish to thank M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, for accepting my manuscript for publication into a book

I sincerely thank all my teachers, well-wishers, colleagues, friends and students, who inspired

me to write the book

My heartfelt thanks to my mother, wife, daughter and son Their sacrifices and support have been overwhelming

I wish to take this opportunity to express my sincere gratitude to all the people responsible for the publication of the book

Finally, I thank God Almighty for this wonderful science of orthodontics

Acknowledgments

www.ajlobby.com

• Orthodontics in India 5 • Evolution of Orthodontic Appliances 5

General Principles and Concepts 9

• Definitions 9 • Factors Affecting Physical Growth 10 • Concepts of Growth 11

• Types of Growth Data 17 • Methods of Gathering Growth Data 18 • Methods of Studying Growth 19 • Mechanism of Bone Growth 20 • Osteogenesis (Mechanism

of Bone Formation) 20 • Theories of Growth 23

Prenatal Growth and Development 28

• Period of Ovum 28 • Period of Embryo 28 • Prenatal Development of Maxilla 32

• Development of Palate 32 • Development of Maxillary Sinus 33 • Develop­

ment of Tongue 33 • Prenatal Development of Mandible 34 • Meckel’s Cartilage 34 • Endochondral Bone Formation 35 • Prenatal Growth of Temporo mandibular joint 35

Postnatal Growth and Development 35

• Neonatal Skeleton 36 • Postnatal Growth of the Cranial Vault 36 • Postnatal Growth of the Cranial Base 36 • Postnatal Growth of Maxilla 38 • Postnatal Growth of Mandible 40 • Mandibular Rotation 42 • Postnatal Growth of TMJ 43 Summary of Facial Growth Changes 44

www.ajlobby.com

Development of Dentition and Occlusion 44

• Bud Stage 45 • Cap Stage 45 • Bell Stage 45 • Periods of Occlusal Development 46

• Predental Period 46 • Deciduous Dentition Period 48 • Mixed Dentition Period 50

• Permanent Dentition Period 53

• Psychology (Study of Psyche) 67 • Theories of Psychological Development 67

• Beha vior in Orthodontics 72 • Behavior Development 73 • Behavior Mana ge ment 73

• Basic Approaches to Child Management in Orthodontics 77 • Ephebodontics 77

Clinical Importance of Growth and Development in Orthodontics 78

• Infancy and Early Childhood 78 • Juvenile Period 79 • Adolescent Growth 79

• Clinical Implications of Regional Development 79

Occlusion 83

• Terminology 83 • Types of Cusps 84 • Arrangement of Teeth in Humans 84

• Imaginary Occlusal Planes and Curves 84 • Centric Relation and Cen tric Occlusion 85 • Centric Contacts 85 • Eccentric Occlusion 86 • Disclu sion 86 • Angle’s Concept of Normal Occlusion 87 • Begg’s Concept of Normal Occlu sion (Attritional Occlusion) 88 • Roth’s Concept of Functi onal Occlusion 88 • Andrews Six Keys to Normal Occlusion 89

Habits 135

• Definition 135 • Classification of Habits 135 • Thumb Sucking and Finger

Sucking 137 • Tongue Thrusting Habit 142 • Mouth­breathing 147 • Lip Biting

and Lip Sucking 151 • Bruxism 151 • Finger Nail Biting 153 • Tongue Sucking 154

• Pillowing Habits 154

Nutrition in Orthodontics 154

• Effect of Nutritional Status on Tooth Movement and Tissue Response to Appli ances 154 • Dietary Counseling for Plaque Control and General Health in the

Orthodontic Patient 156 • Nutritional Considerations in the Orthognathic Surgical

Patient 156 • Nutritional Factors in the Etiology of Craniofacial Anomalies 157

• Esthetics in Orthodontics 166 • Golden Section 167

Diagnostic Aids in Orthodontics 171

• Essential Diagnostic Aids 171 • Supplemental Diagnostic Aids 172 • Case History 172 • Clinical and General Examinations 173 • Functional Examination 180

• Orthodontic Study Models 185 • Total Dentition Space Analysis 193 • Inference

to Deficits and Decisions 195 • Radiographs Used In Orthodontic Diagnosis 196

Cephalometrics 198 • Facial Photographs 218

Computers in Orthodontics 236

• Characteristics of a Computer 237 • Uses of Computer in Orthodontics 238

Sterilization in Orthodontics 243

• Sterilization 243

General Factors in Orthodontic Treatment Planning 246

• Setting­up Goals 246 • Enlisting the Treatment Objectives 246 • Age Factor in

Orthodontics 249 • Treatment and Age 250 • Tooth Movement and Age 251 • Young Versus Adult Patients 251 • Phases of Orthodontic Treatment 252 • Limitations in

Orthodontics 253

Methods of Gaining Space 253

• Proximal stripping (Reprox i mi zation, Slenderization, Disking and Proximal

Slicing) 254 • Expansion 255 • Types of Appliances Used 257 • Slow Expansion 260

www.ajlobby.com

• Extractions in Orthodontics 262 • Distalization 267 • Uprighting of Molars 269

• Derotation of Posterior Teeth 269 • Proclination of Anterior Teeth 269

Treatment Planning in Class I Malocclusion 269

• Clinical Features of Class I Malocclusion 269 • Midline Diastema 272 • Crossbite 275

• Impacted Teeth 281

Treatment Planning in Class II Malocclusion 284

• Class II Division 1 Malocclusion 285 • Class II Division 2 Malocclusion 287

Treatment Planning in Class III Malocclusion 288

• Clinical Features of Class III Malocclusion 288 • Skeletal Features of Class III Malocclusion 289

Drugs Used in Orthodontics 290

• Prophylactic Antibiotics for Prevention of Infective Endocarditis 290

Mechanics of Tooth Movement 298

• Newton’s Laws of Motion 298 • Types of Tooth Movements 299 • Types of Force 301

Biology of Tooth Movement 302

• Physiologic Tooth Movement 302 • Tooth Mobility 305 • Histology of Tooth Movement 305 • Optimum Orthodontic Force 306 • Hyalinization 307 • Theories

of Tooth Movement 308 • Phases of Tooth Movement 309 • Biochemical Reaction

to Orthodontic Tooth Movement 310 • Bone Resorption 311 • Bone Deposition 311

Anchorage in Orthodontics 314

• Definition (Graber) 314 • Classification 314 • Sources of Anchorage 315

• Implants as Anchorage in Orthodontics 320 • Anchorage Loss 325

8 Preventive and Interceptive Orthodontics 326

Preventive Orthodontics 326

• Definition 326 • Caries Control 327 • Oral Habits Check­up and Educating Patients and Parents 328 • Space Maintainers 328

Interceptive Orthodontics 333

• Definition 333 • Serial Extractions 334 • Developing Anterior Crossbite Correction

337 • Preorthodontic Trainers 340 • Clinical Management 341 • Muscle Exercises 341

• Classification of Orthodontic Appliances 344 • Ideal Requirements of an Orthodontic Appliance 345

Removable Appliances 345

• Indications for Removable Appliances 345 • Advantages of Removable Appliances

345 • Disadvantages of Removable Appliances 346 • Components of Removable Appliances 346

Fixed Appliances 364

• Advantages of Fixed Appliances 364 • Disadvantages of Fixed Appliances 365

• Banding 366 • Bonding 367 • Components of Fixed Orthodontic Appliances 368

I Active Components 369 • II Passive Components 372 • Fixed Appliance Techniques 375 • Oral Hygiene in Fixed Appliance Treatment 379

Orthopedic Appliances 382

• Basis for Orthopedic Appliances 382 • Biomechanical Consideration 383

• Headgear 384 • Protraction Face Mask Therapy 388 • Factors Governing Variability in Clinical Response 389 • Chin Cup Therapy 390

Functional Appliances 390

• Definition 391 • Classification of Functional Appliances 391 • Advantages of Functional Appliances 393 • Limitations of Functional Appliances 393 • Action of Functional Appliances 394 • Visual Treatment Objective 395 • Vestibular Screen (Oral Screen) 395 • Activator 397 • Management of the Appliance 400 • Wunderer’s Modification 401 • The Reduced Activator or Cybernator of Schmuth 402

• Pro pulsor 402 • Karwetzky Modification 402 • Herren’s Modification of the Activator 402 • Function Regulator (Frankel Appliance) 403 • Bionator 407 • Twin Block Appliance 408 • Herbst Appliance 409

Minor Surgical Procedures 429

• Extractions 429 • Surgical Exposure of Impacted Teeth 430 • Frenectomy 431

• Pericision (Circumferential Supracrestal Fibrotomy or CSF Procedure) 431

• Corticotomy 432 • Orthodontic Implants 432

Orthognathic Surgery 433

• Etiology of Dentofacial Deformities 433 • Orthognathic Surgery 434 • Presurgical Orthodontics 436 • Maxillary 437 • Mandibular Surgeries 440

Distraction Osteogenesis 442

• Definition 442 • Historical Perspective 442 • Indications 443 • Advantages 443

• Disadvantages 443 • Preoperative Clinical Examination 444 • Growth and Stability after Distraction 446

Adult Orthodontics 448

• Reasons for Increase in Adult Patients 448 • Biomechanical Considerations 450

• Diagnosis and Adult Orthodontics 451 • Treatment Aspects in Adult Ortho ­ dontics 452

Orthodontics in Multispecialty Approach 455

• Multispecialty Ortho dontic Treatment 455 • Orthodontic­periodontic Inter­ relation ship 457

Orthodontic Management of TMJ and Occlusal Disorders 462

• Biomechanics 463 • Temporomandibular Joint Pathology 464 • Signs and Symptoms of TMJ Disorders 465 • Orthopedic Dysfunction 466 • Diagnosis 468

Management 469

Orthodontic Management of Cleft Lip and Palate 472

• Incidence 472 • Embryological Background 473 • Family Counseling 480

Orthodontic Management of Craniofacial Syndromes 480

• Orthodontic Management of Cleidocranial Dysplasia 480 • Orthodontic Management of Obstructive Sleep Apnea Syndrome 482 • Orthodontic and Temporomandi bular Joint Considerations in Treatment of Patients with Ehlers­Danlos Syndrome 483

Orthodontic Management of Medically Compromised Patients 484

• Management of Physically Handicapped Child 484 • Management of Orthodontic Patients with a History of Rheumatic Fever or Congenital Heart Disease 485

• Orthodontic Management of Patients with Bleeding Disorders 486 • Orthodontic Management of Patients with Hematologic Malignancies 487 • Orthodontic Management of Patients with Endocrine Disorders 488 • Orthodontic Management

of Patients with Diabetes 489 • Orthodontic Management of Patients with Cystic Fibrosis 491 • Orthodontic Management of Patients with Juvenile Rheumatoid Arthritis 491 • Orthodontic Management of Patients with Renal Failure 492

Forensic Orthodontics 493

• Forensic Dentistry 493 • Role of Orthodontist 494 • Dermatoglyphics 495

Orthodontic Practice 496

• Ideal Orthodontic Services 496 • Typical Orthodontic Practice Organization 496

• Orthodontic Work Environment 499

Medicolegal Considerations in Orthodontics 504

• TEGDMA 520 • Orthodontic Cements 520 • Sealants and Adhesion Promoters 524

• Conditioning and Crystal Growth Systems 525 • Elastics and Elastomerics 526

• Magnets in Orthodontics 526 • Soldering and Welding 528 • Other Dental Materials 534

Acrylic Materials 542

• Ideal Requirements for Dental Resin 542 • Acrylic Resins 542

Finishing and Polishing Materials 545

• Commonly used Abrasives 545

Implant Materials in Orthodontics 546

• History 546 • Metals and Alloys 546 • Other Metals and Alloys 547 • Endosteal and Subperiosteal Implants 548

Orthodontic Instruments 549

• Adam’s Pliers (Universal Pliers) 549 • Arch­forming Pliers (Arch­contouring Pliers, De la Rossa Pliers) 549 • Band Burnisher (Beaver­tail Burnisher) 549

• Band­contouring Pliers 550 • Band Pusher (Mershon Band Pusher) 550 • Band­

Removing (Debanding) Pliers, Anterior 550 • Band­Removing (Debanding) Pliers, Posterior 550 • Band Seater (Band Biter) 551 • Bird­beak (No 139) Pliers 551

• Bracket­positioning Instrument (Bracket­height Gauge, Boone’s Gauge) 551

• Bracket­removing Pliers (Debonding Pliers) 552 • Conversion Instrument 552 Coon Ligature­tying Pliers 552 • Distal­end Cutter 552 • Elastic Separator Pliers (Sep arator Pliers) 553 • Facebow­adjusting Pliers 553 • Hard Wire Cutter 553

• Hemostat (Mosquito Pliers) 553 • Howes Utility Pliers 554 • Ligature

Director (Pitchfork Instrument, Tie in Tucker) 554 • Light­wire Pliers 554

• Mathieu­style Ligature­tying Pliers 555 • Parallel­action Pliers with Cutter (Sargent’s heavy­duty Pliers) 555 • Pin and Ligature Wire Cutter 555

• Serrated Band Plugger (Serrated Amalgam Plugger) 556 • Steiner Ligature­

tying Pliers 556 • Torquing Key 556 • Triple­beaked Pliers (Three Prong Pliers,

Three Jaw Pliers, Clasp­adjusting Pliers) 556 • Turret 557 • Tweed Arch­adjusting (No 142) Pliers 557 • Tweed Loop­forming Pliers (Omega Pliers, Optical Pliers) 557

• Weingart Utility Pliers 558

INTRODUCTION TO

ORTHODONTICS

The term orthodontia was apparently used first

by the Frenchman Le Foulon in 1839 The name

of the specialty Orthodontics comes from two

Greek words “ortho” meaning right or correct

“odontos” meaning tooth and “ics” meaning

science

Orthodontics is the branch of dentistry

concerned with prevention, interception and

correction of malocclusion and other develop­

mental abnormalities of the dentofacial region

DEFINITIONS

British Society for Study of

Orthodontics (1922)

“Orthodontics includes the study of the

gro wth and development of the jaws and

face particularly, and the body generally,

as influencing the position of the teeth; the

study of action and reaction of internal and

external influences on the develop ment; and

the prevention and correction of arrested and

American Association of Orthodontics (1993)

American Association of Orthodontics (AAO) renamed the specialty from Orthodontics to Orthodontics and Dentofacial orthopedics in

1984 They modified the definition of orthod­ontics in 1993 as, “The area and specialty of dentistry concerned with the supervision, guidance and correction of the growing or mature dentofacial structures, including those conditions that require movement of teeth or correction of malrelationships and malfor mations of their related structures and

Introduction

1

the adjustment of relationships between and

among teeth and facial bones by the appli­

cation of forces and/or the stimulation and

redirection of fun ctional forces within the

craniofacial complex Major responsibilities

of orthodontic practice include the diagnosis,

prevention, interception and treatment of

all forms of malocclusion of the teeth and

associated alterations of their surrounding

structures; the design, application and control

of functional and corrective appliances; and

the guidance of the dentition and its supporting

structures to attain and maintain optimal

occlusal relations, physiologic function and

esthetic harmony of facial structures.”

ORTHODONTIST

Orthodontist (Orthodontic Specialist)

A graduate of an accredited dental school who

additionally has followed a postgraduate full­

time academic program in orthodontics, in

accordance with the requirements of his/her

national, state, or provincial law The duration

of the postgraduate orthodontic training

varies in different countries or areas of the

world For example, in the USA a two­year

full­time academic training beyond general

dental school is required to obtain the title

of ortho dontist, whereas in the European

Union and India the minimum requirement

is three years

Branches of Orthodontics

Orthodontics can be broadly divided into:

Preventive Orthodontics

It is the action taken to preserve the integrity of

what appears to be normal at a specific time

Interceptive Orthodontics

It is that phase of science and art of orthodontics employed to recognize and eliminate potential irregularities and malpositions in the developing dentofacial complex

Corrective Orthodontics

Corrective orthodontics recognizes the existing malocclusion and the need for employing certain technical procedures to reduce or eliminate the problem and the attendant sequelae

Surgical Orthodontics

They are the surgical procedures that are undertaken in conjunction with or as an adjunct to orthodontic treatment

Aims of Orthodontic Treatment

The aims and objectives of orthodontic treatment has been summarized by Jackson

as Jackson’s triad, they are:

1 Functional efficiency: The orthodontic

treatment should aim at improving the functions of the stomatognathic system,

as many malocclusions tend to alter the normal functions

2 Structural balance: Orthodontic therapy

should maintain a structural balance between hard tissues of teeth and bones to that of soft tissues of muscles and tongue

3 Esthetic harmony: Many malocclusions

are associated with poor facial appearance and dental esthetics; hence orthodontic treatment should aim at improving the esthetics of face and teeth

Unfavorable Sequelae of Malocclusion

Malocclusion leads to many problems that can

be listed as:

1 Unfavorable psychological and social

squeal

a Introversion, self­consciousness

b Response to uncomplimentary nick­

names like Bugs bunny, Buckteeth

or Bucky beaver

2 Poor appearance: Interference with

normal growth and development and

accomplish­ment of normal pattern

a Cross bites causing facial asym­

metries

3 Improper or abnormal muscle function

a Compensatory muscle activities

such as hyperactive mentalis muscle

activity, hypoactive upper lip, increase

buccinator pressures and ton gue

thrust that occurs as a result of spatial

relationship of teeth and jaws

These activities are unfavorable and

serve to increase the departure from

9 Increased caries incidence

10 Predilection to periodontal disease

11 Temporomandibular joint problems:

Functional problems

12 Predilection to accidents

13 Impacted and unerupted teeth, poss ible

follicular cysts, damage to other teeth

14 Prosthetic rehabilitation compli c ations:

Space problems, teeth tipped and rece­

iving abnormal stress

Need for Orthodontic Treatment

Orthodontic treatment is required to:

1 Improvement of esthetics

2 Restoration of proper function of teeth

3 Reduction of susceptibility of dental caries

4 Elimination of pathological conditions

of the gingival and periodontal tissues caused due to malocclusion of teeth

5 Correction of malposed teeth prior

to construction of partial denture or bridge work

6 Elimination of harmful habits

7 Prevention and correction of tempo­romandibular joint abnormalities

8 To correct speech defects

9 Decompensation before taking up the case for surgical correction

10 Additional treatment after surgical corr­ection of congenital deformities and skeletal malocclusions

11 As a result of accidental injury, loss of teeth or interference with occlusions may make orthodontic treatment necessary

12 To improve the personality of an individual

Scope of Orthodontic Treatment

The scopes of orthodontic treatments are:

Orthodontic tooth movement: Application

of forces are responsible for altering the tooth positions, dental malocclusions are treated effectively by altering the tooth positions Orthodontics is mainly employed

to alter permanently the tooth positions Tooth movement can be undertaken in all three planes, transverse, vertical and sagittal

Dentofacial orthopedic growth modification:

Malocclusions associated with skeletal dis­har mony can be corrected to normal by appli­cation of orthopedic forces which are capable

of redirecting, modifying and restraining skeletal growth patterns

Altering the soft tissue patterns: Favorable

changes can be brought about in the soft tissues by orthodontic treatment that are

responsible for normal development and

maintenance of dentition and skeleton

HISTORY OF ORTHODONTICS

Orthodontics is considered as the oldest

specialty of dentistry Evidences suggest that

attempts were made to treat malocclusion as

early as 1000 BC Primitive appliances to move

teeth have been found in Greek and Etruscan

excavations

The Greek physician Hippocrates (460–377

BC) is believed to be the father of medicine He

is the first person to establish medical tradition

based on facts rather than religion of rancy A

number of references on teeth and jaws are

found in his writings

Aristotle (384–322 BC) was a Greek philo­

sopher who gave medical science the first

system of comparative anatomy; he compared

human teeth with other species

The first recorded suggestion for active

treatment of malocclusion was by Aulius

Cornelius Celcus (25 BC–50 AD) who advocated

the use of finger pressure to move the teeth

Pierre Fauchard, a French dentist, is

considered the founder of modern dentistry

and he is known as Father of Dentistry As early

as 1723, he developed what is probably the first

orthodontic appliance called a Bandelette that

was designed to expand the dental arch

Norman Kingsley, an American dentist,

was the first to use extraoral force to correct

pro truding teeth He is considered as one of

pioneers in cleft palate treatment

Emerson C Angell (1823–1903) was the

first person to advocate the opening of the mid

palatal suture, a procedure that later came to

be known as rapid maxillary expansion

William E Magill (1823–1896) was the first

person to band teeth for active tooth move­

ment

Henry A Baker in 1893, introduced what

is called Baker’s anchorage or the use of intermaxillary elastics to treat malocclusion Edward H Angle (1855–1930) (Fig 1.1)

is considered the Father of Modern Orthod­ontics for his numerous contributions to this specialty Through his leadership, orthod­ontics was separated from other branches

of dentistry to establish itself as a specialty Angle’s contri butions include a classification

of malocclusion and orthodontic appliances such as Pin and tube appliance, E­arch, Ribbon arch and Edgewise appliance Angle also started a school of Orthodontics in St Louis, New London, Conn ecticut in which many of the pioneer orthod ontists were trained Angle believed that the whole compliment of teeth could be retained and yet good occlusion could be achieved He thus advocated arch expansion for most patients

Calvin S Case (1847–1923) believed that facial improvement was a guide to orthodontic treatment Case also claims to be the first orthodontist to use intermaxillary elastics

He was a critic of Angle and opposed Angle’s

Figure 1.1: Edward H Angle

philosophy of arch expansion to treat most

cases He advocated the removal of certain

teeth to achieve stable treatment results and

to improve facial esthetics

Martin Dewey (1881–1933) was an ardent

champion of nonextraction Dewey also modi­

fied Angle’s classification of maloc clusion

In 1931, Holly Broadbent and Hofarth inde­

pen dently developed cephalometric radio­

graphy, which standardized the positioning

of the head in relation to the film and X­ray

source This can be considered a major

advance ment in orthodontic diagnosis and

treatment planning

Buonocore in 1955, introduced the acid

etch technique; this enabled direct bonding of

orthodontic attachments to the enamel which

greatly enhanced esthetics

Raymond P Begg of Australia introduced a

light wire fixed appliance that was based on the

concept of differential force He also advocated

the need for extraction of some teeth to achieve

stable results

While American orthodontists were

show ing keen interest in improving fixed

orthodontic appliances, their European

counterparts continued to develop removable

and functional appliances for guidance of

growth

Pierre Robin in 1902 introduced mono­

block, which protruded the mandible in cases

of glossoptosis

Viggo Anderson in 1910, developed the

activator, which made use of the facial muscul­

ature to guide the growth of the jaws

Rolf Frankel in 1969, proposed the function

regulator to treat variety of skeletal malo­

cclusions

Lawrance F Andrews introduced the

Straight Wire Appliance in 1972; this was a

preadjusted appliance in which the brackets

were pre­programmed to accomplish the

desired tooth movements in all the three

planes of space This is considered a major advancement in improving orthodontic treatment results with minimal possible wire bending

ORTHODONTICS IN INDIA

In India, the first dental college, Calcutta Dental College and Hospital was started in the year 1920 by Dr Rafiuddin Ahmed in his private chamber Dr Ahmed, the Father of Dentistry in India is also known as “The Grand Old Man of Dentistry” He is credited with the first edition

of “The Indian Dental Journal” in October

1925, foundation of the “All India Dental Association” in the year 1927, drafting and passing of the Bengal Dentist Act in 1939, and the passing of the Indian Dentist Act in 1948 Dentistry as a subject was introduced as a

2 years diploma course to “Licentiate in Dental Science (LDSc) It was changed to the 3 years course in the year 1926 and further modified

to the present 4 years BDS course in 1935

EVOLUTION OF ORTHODONTIC APPLIANCES

1728 In his work Le Chirurgien Dentiste, Pierre Fauchard (Vannes 1678–Paris 1761) laid the foundations of ortho­dontic science Among other things,

he illustrated a number of orthodontic treatises and a rudimental orthodontic expansion device called a bandelette, the invention of which was without attribution because it had been use for some time This brace consisted of

a band of silver stabilized with metal

or plant—fiber bindings He also descri bed the surgical straightening of individual teeth

1741 The term orthopedics in reference to the

stomatognathic apparatus appe ared for

the first time in L’ Orthopédie ou l’Art de

Prevenir et de Corriger dans les Enfans

les Difformités du Corps by Nicolas

Andry De Bois Regard (1658–1672)

1771 John Hunter (Long Calder wood

1728–London 1793), an anatomist and

surgery teacher, devoted three cha pters

of his Natural History of the Human

Teeth to malocclusions, even proposing

a classifi cation of them

1803 A chin cup for nonorthodontic pur­

poses was first described by Francois

Cellier, who used it to prevent postex­

traction hemorrhage

1803 Joseph Fox (1776–1816), a student of

Hunter, published ‘The Natural History

of the Human Teeth—Describing the

Proper Mode of Treatment to Prevent

Irregularities of the Teeth’

1809 JB Lamarck (1744–1829), a zoologist,

wrote of the importance of function

in the development of organs and the

species, forerunning Wilhelm Roux’s

theories on functional adaptation

1819 Michael Faraday prepared the first

iron— chromium alloy, a precursor of

stainless steel

1826 LJ Catalan (1776–1830) utilized the

principles and method of the inclined

plane

1826 CF Delabarre, (1777–1862), in his Meth­

ode Naturelle de Diriger la Seconde

Dentition, accurately des cribed tooth

transition, emphasizing the importance

of primary teeth

1829 In his Manual of Human Anatomy,

JF Meckel (1781–1833) described the

cartilage of the first branchial arch

1834 William Imrie named thumb­sucking

as an etiologic role in malocclusions

1836 F Kneisel (1797–1883) published Der Schiefstand der Zähne, the first work

in German on malocclusions

1839 The American Journal of Dental Science, the first journal devoted entirely to dentistry

1839 A French scholar, Jacoues Lefoulon, coi­ned the term orthodontosie in a series

of articles on “Orthopedia dentaire”, which appeared in the Gazette des Hopitaux

1840 C Goodyear (1800–1860) discovered that natural rubber hardens when com­bined with a small amount of sulfur

1840 The initiative of Chapin Harris and Horace H Hayden (1769–1844), the first school of dentistry, the College of Dental Surgery in Baltimore

1840 CS Brewster (1790–1870), an American dentist living in Paris, constructed a rubber orthodontic device (Vulcanite plate or Regulierungs platte, according

to Schnizer) equipped with springs, introducing a material different from those used until that time

1841 JS Guinnell described the first ortho­pedic chin cap appliance

1843 Malagan­Antoine Desiderabode (1781–1850) published ‘Nouveaux ele ments com plets de la science et al l’art du dentiste’, in which he intro duced the concept of Leeway space and the balance

of force between lips and tongue

1848 WE Dwinelle (1819–1896) made an orthodontic plate with screws to widen dental arches The screws used were jackscrews

1859 Lefoulon published a text entirely dev­

o ted to orthodontics

1860 Englishman CR Coffin first introduced the use of piano wire to expand the maxillary arch

1864 T Ballard (1836–1878) reaffirmed the

etiologic role played by prolonged

sucking (fruitless sucking) in maloc­

clusions

1866 Norman Kingsley perfected occipital

anchorage and extraoral forces

1876 AH Thompson (1849–1914) recog nized

the importance of occlusal forces in

den toal veolar development and in

orthod ontic movement

1881 Walter Harris Coffin (1853–1916), an

English dentist and son of CR Coffin,

perfected the expansion technique

introduced years earlier by his father

1887 Edward Angle (1855–1930), an American

dentist, inaugurated fixed orthodontics,

presenting a method based on precise

mechanical principles and introducing

the use of gold multiband devices, the

‘braces’ that would He was the author

of the term malocclusion and surely the

most important figure in the history of

orthodontics, making contributions that

were decisive for the birth of this new

science He fought to transform ortho­

dontics into an independent specialty

and to have it officially taught His

classification of malocclusion, based on

the position of the first molars, remians

funda mental even today

1888 John Nutting Farrar (1839–1913), a

New York dentist, published the first

volume of a basic work, Treatise on

the Irregul arities of the Teeth and Their

Corr ection In his orthodontic work, he

paid great attention to the physiologic

and pathologic changes in tissues His

teachings also deeply influenced Viggo

Andresen, whose writings show how

the activator fully respects the principles

Farrar established for intermittent forces

1888 Wilhelm Roux (Jena 1850 – Halle

1924), an anatomist and follower of

the Darwin school, founded the first research institute on development in Germany He devoted his life to the subject, working out the theory of functional adaptation

1890 Walter H Coffin created a vulcanite orthodontic appliance with a W­shaped spring to expand the maxilla

1895 The fundamental work by Wilhelm Roux, devoted to the mechanisms that regulate development, was published

20th Century before and during World War–I

1901 Edward Angle and a group of his students founded the Society of Orthodontics in St Louis

1902 Pierre Robin (Charolles en Bourgogne 1867–Paris 1950), a French doctor and professor of stomatology, described the construction and properties of the mono bloc

1908 Viggo Andresen (Copenhagen 1870–1950) experimented with a removable retention plate following active multi­band therapy in his daughter and was surprised to obtain further clinical improvements This device was named

an activator

1909 Emil Herbst (1842–1917), a German dentist, designed a fixed appliance for forced mandibular advancement

1911 In the wake of Sandstedt’s research, A Oppen heim discovered the damage done by excessive force and recom­men ded the use of light and inter­mittent pressure

1918 Alfred Paul Rogers, a professor at Har­vard Dental School in Boston, published

an article in which he defined muscles

as “living orthodontic appli ances”

1922 Pierre Robin published Eumorphia, a collection of his writings

1926 Edmondo Muzj (1894–1994) intro­

duced the teaching of orthodontics at

the University of Bologna

1927 Studying craniofacial growth and

anthropometry, M Hellman came to

the conclusion that malocclusions are

caused by growth disturbances

1929 Studying growth and comparing

humans with other mammals, W Todd

confirmed Heilman’s conclusions,

stating that growth leads to a modifi­

cation in the proportions of the various

parts

1933 The Krupp company marketed the first

stainless steel dental crowns, shortly

followed by clasps, wires, and other

materials

1934 Gustave Korkhaus invited FM Watry

to Cologne, where he expounded on

Robin’s idea and method The text of this

conference was published in the journal

Fortschritte der Kieferorthopadie

1936 After more than 10 years of close colla­

boration, Viggo Andresen and Karl

Haupl published a book on functional

jawbone orthopedics, Funktions­

Kieferorthopädie

1938 Arthur Martin Schwarz (1887–Vienna

1963) published Gebissreinigung mit

Platten, entirely devoted to orthod ontic

plates

1939 HG Gerlach experimented with the

first open elastic devices, arousing

the strong opposition of K Haupl, who

criticized the changes made to the

activator

1949 Hans Peter Bimler modified Andre­

sen’s activator and created the elastic

occlusal modeler (Elastischer gebiss­

former)

1949 Edmondo Muzi modified the activator,

eliminating the palatal part and intro­

ducing a metal slide curved on the mandibular par to expand the arch

1950 Wilhelm Balters (1893–1973) began to modify Andresen’s activator together with dental technician Fritz Geuer in order to re­educate orofacial disorders

1952 Hans Muhilemann created the propu­lsion device similar to the activator but without metal elements, which would later be perfected by Rudolph Hotz at the University of Zurich

1953 Hugo Stockfisch created the kinetor,

an interesting modification of the acti va tor equipped with elastic mastica­tion planes

1954 H Van Thiel created an activator devoid of the upper part of the palate, predating Klammt’s work

1960 Georg Klammt, a student of Bimler, altered his teacher’s appliance because

he felt it to be too fragile and created the elastisch­offene activator

1960 Melvin Moss, a professor at Columbia University, New York, formulated the

“functional matrix” theory together with his wife, Letty Salentijn

1960 Rolf Frankel published the first clinical results obtained with the function reg­

ul ator

1960 Georg Schmuth created the kyber­nator, an appliance deriving from the Bionator with the addition of a classic maxillary vesti bular arch and two mandibular vestibular cushions

1967 Alexander Petrovic formulated his fun­

da mental theories about the different types of cartilage involved in osteogen­esis and individuated the peculiarities

of mandi bular condyle cartilage, which also res ponds to local external stimuli, such as tensing of the lateral pterygoid muscle

GENERAL PRINCIPLES

AND CONCEPTS

Orthodontic treatment requires a good knowl­

edge of anatomy, growth and development of

head, jaws and face It is almost impossible to

plan the orthodontic treatment without having

an idea about the growth and development of

an individual

DEFINITIONS

Growth

There is no universally accepted definition of

growth Various clinicians have defined growth

in different ways

“The self­multiplication of living substance”

(JS Huxley)

“An Increase in size” (Todd)

“Increase in size, change in proportion and

progressive complexity” (Krogman)

“Entire series of sequential anatomic

and physiologic changes taking place from

the beginning of prenatal life to senility”

Development

Development occurs along with growth and is inseparable from it

“Progress Towards Maturity” (Todd)

“All naturally occurring unidirectional changes

in the life of an individual from its existence as a single cell to its elaboration as a multifunctional unit terminating in death” (Moyers)

Thus, development encompasses the normal sequential events between fertilization and death

Growth and Development

2

Stabilization of the adult stage brought about

by growth and development

Differentiation

Differentiation is the change from a generalized

cell or tissue to one that is more specialized,

thus differentiation is a change in quality or

kind

FACTORS AFFECTING PHYSICAL

GROWTH

A number of factors affect the rate timing and

character of growth, they are:

Hereditary

Heredity is one of major factor affects physical

growth Genes influences the size of parts, rate

of growth, and onset of growth and timing of

events Genetic studies of physical growth

make use of twin and family data Differences

between monozygotic and dizygotic twins are

assumed to be differences due to environment

Nutrition

Malnutrition during childhood delays growth

and adolescent spurt in growth, catch­up

growth appears when a favorable nutritional

regimen is supplied early enough Malnutrition

affects the timing of growth and texture of

tissues These effects are reversible to some

extent as when the effects are not very severe

and when proper nutrition is provided

Illness

The usual minor childhood illness ordinarily

may not have a major effect on physical

growth Prolonged and debilitating systemic

illness however can have a marked effect on

normal physical growth and may lead to delay

in maturation

Race

There are six races in world, Caucasian, Negroid, Mongoloid, Alpine, Aboriginals, and Medit erranean Each of these racial groups shows characteristic growth patterns

In India the common racial groups are Dravidian, Indo­aryan, Mongoloid, and turko­iranian Although the differences in growth among different races can be attributed to other nutritional and environmental factors, there seems to be some evidence that race does play a role in growth process For example in American Blacks, calcification and eruption

of teeth occurs almost a year earlier than their white coun terparts

Socioeconomic Factors

Children brought up in affluent and favorable conditions show earlier onset of growth events They also grow to a larger size than children living in unfavorable economic conditions

Family Size and Birth Order

Studies have shown that the first­born babies tend to weigh less at birth and have smaller stature but higher IQ The smaller the family size, the better would be the nutrition and other favorable conditions

Secular Trends

Changes in size and maturation in a large population can be shown to occur with time For example, fifteen years old boys are approximately 5 inches taller than the same age group 50 years back Although there is no satisfactory explanation offered regarding this finding it could possibly be due to changes in socioeconomic conditions and food habits

Climatic and Seasonal Effects

Seasonal variations have been shown to

affect adipose tissue content and the weight

of newborn babies Climatic changes seem to

have little direct effect on rate of growth

Psychological Disturbances

It is seen that children experiencing

stressful conditions display an inhibition of

growth hormone secretion Psychological

disturbances of prolonged duration can hence

markedly retard growth

Exercise

Although exercises may be essential for a

healthy body, strenuous and regular exercises

have not been associated with more favorable

growth Certain aspects of growth such as

development of some motor skills and increase

in muscle mass is found to be influenced by

exercise

CONCEPTS OF GROWTH

Concept of Normality

Normal refers to that which is usually expected,

is ordinarily seen or is typical The concept of

normality must not be equated with that of the

ideal While ideal denotes the central tendency

for the group, normal refers to a range Another

aspect of craniofacial growth is that normality

changes with age Thus what is normally seen

or is expected for one age group may not be

necessarily normal for a different age group

Rhythm of Growth

According to Hooton “Human growth is not a

steady and uniform process wherein all parts

of the body enlarge at the same rate and the

increments of one year are equal to that of

the preceding or succeeding year.” However

there seems to be a rhythm during the growth process This growth rhythm is most clearly seen in stature or body height

The first wave of growth is seen in both sexes from birth to the fifth or sixth year It is most intense and rapid during the first two years There follows a slower increase terminating

in boys about the tenth to twelfth year and in girls no later than the tenth year Then both sexes enter upon another period of accelerated growth corresponding to adolescence that is completed in girls between the fourteenth and sixteenth year, but extends in boys through the sixteenth or eighteenth year Following this, a final period of slow growth is seen which ends between the eighteenth and twentieth years

in females but goes on in boys until about the twenty fifth year

Growth Spurts

Growth does not take place uniformly at all times There seems to be periods where a sudden acceleration of growth occurs This sudden increase in growth is termed “Growth spurts.”

The physiological alteration in hormonal secretion is believed to be the cause for such accentuated growth The timing of the growth spurts differ in boys and girls and are sex linked The greatest increments of growth are actually

at the 3 years age level Second peak is from 6–7 years There is tendency for more boys to have

a One year after birth

b First peak (Deciduous dentition peak): Boys: 3 years, Girls: 3 years

c Second peak (Mixed dentition peak): Boys: 8–11 years, Girls: 7–9 years

d Third peak (Pre­pubertal peak): Boys:

14–16 years, Girls: 11–13 years

Clinical Implications of Growth Spurts

Knowledge of growth spurts is essential for

successful treatment planning in orthodontics

This helps us to decide the timing of orthodontic

treatment, whether to start the treatment at the

time of peak growth or after the active growth

is completed

These are obvious for orthopedic correction

of maxillomandibular relationships Very few

girls seem to show the mixed dentition growth

spurt, all show the pubertal spurt Pubertal

increments still offer the best time for a large

number of cases, as far as predictability, growth

direction, patient management and total

treatment time are concerned

Malocclusions of dental arches can be

treated taking advantage of growth spurts

during the active growth period

Arch expansion and rapid palatal expansion

can be undertaken during maximum growth

Growth spurt is best time for interceptive procedures like, functional appliances, headgear orthopedics, maxillary expansion and chin cup therapy

Malocclusion requiring surgical correction can be undertaken after the growth spurts are completed

Differential Growth

The human body does not grow at the same rate throughout life Different organs grow

at different rates to a different amount and

at different times This is termed differential growth

There are two important aspects of differ­ential growth:

Scammon’s Growth Curve (Fig 2.2)

The body tissues can be broadly classified into four basic types They are lymphoid tissue, neural tissue, general tissue and genital tissue Each of these tissues grows at different times and rates

Lymphoid tissue proliferates rapidly in late childhood and reaches almost 200% of adult size This is an adaptation to protect child from infection, as they are more prone to it By about

Figure 2.1: Growth spurts

Figure 2.2: Scammon’s growth curve

18 years of age lymphoid tissue undergoes

involution to reach adult size

Neural tissue grows very rapidly and almost

reaches adult size by 6–7 years of age Very little

growth of neural tissue occurs after 6–7 years

This facilitates intake of further knowledge

General tissue or visceral tissue consists of

the muscles, bones and other organs These

tissues exhibit an ‘S’ shaped curve with rapid

growth up to 2–3 years of age followed by a

slow phase of growth between 3–10 years After

the tenth year, a rapid phase of growth occurs

terminating by the 18–20th year

Genital tissue consists of reproductive

organs They show negligible growth until

puberty; however they grow rapidly at puberty

reaching adult size after which growth ceases

Cephalocaudal Gradient Growth (Fig 2.3)

Cephalocaudal gradient of growth simply

means that there is an axis of increased

growth extending from head towards the

feet A comparison of the body proportions

between prenatal and postnatal life reveals that

postnatal growth of regions of the body that are

away from the hypophysis is more

This concept may be illustrated by

following

The head takes up about 50% of the total body length around the third month of intrauterine life At the time of birth, the trunk and the limbs have grown more than the head thereby reducing the head to about 30% of body length The overall pattern of growth continues with a progressive reduction in the relative size of the head to about 12% in adult.The lower limbs are rudimentary around the 2nd month of intrauterine life They later grow and represent almost 50% of the body length at adulthood

This increased gradient of growth is evident even within the head and face (Fig 2.4) At the time of birth, the cranium is proportionally larger than the face Postnatally the face grows more than the cranium The growth of maxilla, which is close to cranium, is completed first when compared to mandible

Growth in Height

When a chart showing height for age is constructed from date taken from a large number of children variations in height can

be found out When increments of growth are plotted on a chart to form a velocity curve the rate of growth is seen to decrease from birth to adolescence at which time a marked spurt in height growth is seen in both sexes at puberty This is known as adolescent

Figure 2.3: Cephalocaudal gradient growth Figure 2.4: Cephalocaudal gradient in head

spurt, the prepubertal acceleration, or the

circumpubertal acceleration The earlier onset

of the spurt in females is seen, at about 10.5–11

yrs in girls, and 12.5–13 yrs in boys The spurt

lasts about 2–2½ yrs in both sexes During

growth spurt boys grow about 8 inches in

height, whereas girls grow about 6 inches

In girls, menarche always follows the peak

velocity of the adolescent spurt in height

The conclusion of the spurt is followed by

rapid slowing of growth, girls reaching 98%

of their final height by 16½ years and boys

reach the same stage at 17¾ years One reason

the females are shorter on average than

males is that they grow for a shorter period

of time than males during postnatal growth

(Fig 2.5)

Six Types of Height Growth in Children

1 Average growers: They follow the middle

range of the distance curve and comprise

about 2/3 rds of all children

2 Early maturing: These children are taller

in childhood because they have matured

faster than average They are usually both

particularly tall as adults

3 Genetically tall: These children are taller

than average children and will be tall as adults

4 Late maturing: These children are shorter

than average in childhood because of their late maturing and will eventually be adults

of average stature

5 Genetically short: These children are short

as children and will be short adults

6 The sixth group of children is made up

of the children who start puberty either early or late and subsequently, have either much less or much more growth in height than expected Those children who enter puberty early finish growing much earlier than those entering puberty at a late age

Growth in Weight

In comparison to height, there is much more variation in weight measurements With height, only three components are measured: the bones, cartilage, and skin However, with weight, every tissue in the body is involved Weight at birth is more variable than length

At birth, full­term females are on the average about 5 oz lighter than full­term males Small mothers have small babies Later children in

a family are usually heavier than the first born children Weight gain is rapid during the first

2 years of postnatal growth This is followed by

a period of steady increase until the adole scent spurt At ages 11–13 years of age girls are, on aver age, heavier than boys Following their ado lescent spurt, boys become heavier The velocity of weight growth decreases from birth

to about 2 years of age after which it slowly acce lerates until the onset of the adolescent spurt During the spurt boys may add 45 pounds and girls 35 pounds to their weight The average age for the adolescent weight spurt is

of less magnitude in girls compared with boys The peak velocity for weight spurt lage behind

Figure 2.5: Height chart

the peak velocity for height on an average of 3

months The adolescent first becomes taller

and then begins to fill out in weight Similarly,

body does not reach its adult value until after

adult height has been attained

Indices of Maturity

Several methods are used to assess the level

of mat urity attained by child during postnatal

gro wth Children of the same age vary in

their maturity status a great deal, therefore,

several bio lo gic maturity indicators have been

developed to assess the prognosis toward

full maturation of an individual at various

times during growth The dental age maturity

indicator based on eru ption age because

it is useful throughout the deve lop ment of

the teeth, not just during the narrow period

covered by eruption

Maturity indicators differ for sexes, females

maturing earlier than males throughout

postnatal growth

Biologic Maturity Indicators

Morphologic Age

It is based on height A child’s height can be

compared with those of his same age group

and other age groups to determine where

he stands in relation to others Height or

morphologic age is useful as maturity indicator

from late infancy to early adulthood

Chronologic Age

The most commonly and easily determined

dev elop mental age parameter is the

chronological age, which is simply figured

from the child’s date of birth Since child has

his own characteristics growth time clock,

there is early, middle and late maturation

chronological age, neither accurate indicators

of stage of development, not is a good predictor

of growth potential

Somatotypic Age

In overall assessment of child, a general body type which is also called as somatotype is considered Sheldon divides somatotype into three categories; ectomorph, mesomorph and endomorph

The ectomorph (high development of ectodermal derivatives) is tall and lean with digestive structures are not well­developed The endomorph (high development of endodermal derivatives) is stocky, has abundant subcut­aneous fat and has digestive viscera that are highly developed; somatic structures are relati­vely underdeveloped The mesomorph (high development of mesodermal derivatives) is upright, sturdy and athletic, his extremities are long and slender with minimal subcutaneous fat and muscle tissue

In general, the ectomorph is a late maturer, whereas an endomorph is an early maturer

in terms of chronologic age Although somatotype may give a gestalt about the child’s develop­mental pattern, it is not an accurate predictor

Height and Weight Age

Height has been considered as convenient determinant of developmental age The standard growth commonly employed to characterize a child’s height compared to that

of children of some chronological age is used

to assess developmental age It is generally seen that after age 2 each child tends to follow the same percentile on the growth curve until the puberty, when deviation may occur because of timing of the spurt differs among adolescents Since each child’s height is related

to genetic and environ mental factors as well

as to chronologic age, it is clear that a single height measurement is limited as a predictor

of developmental age Not all the children have same height at the same percentile

Dental Age

Dental age is based on two different methods of

assessment The most commonly used method

is the observation of age at eruption of the

primary and permanent teeth This might be

called tooth eruption age The second method

involves rating of tooth development from

crown calcification to root completion using

X­rays of the unerupted and developing teeth

Dental age maturity indicators are useful from

birth to early adolescence

Sexual Age

Sexual age refers to development of secondary

sex characters, breast development, and

menarche in females; penis and testis

growth in males; and axillary and pubic

hair development in both sexes This type of

indicator is useful only for adolescent growth

Skeletal Age

Skeletal age is determined by assessing

the development of bones in the hand and

wrist The development of bones from the

appearances of calcification centers to

epiphyseal plate closure occurs in the hand

and wrist throughout the entire postnatal

growth period and therefore provides a

useful means for assessing biologic maturity

A total of 51 separate centers of bone growth

are located in the hand and wrist An atlas of

hand wrist development has been developed,

which is useful in rating the maturity status of

an individual child

Facial Age

The ultimate goal of developmental growth

assessment of children is the facial age in

order to identfy where they are on their

own facial growth curve and use this as a

predictor of future growth In addition to

the developmental age assessment, the most commonly used method of analysis between the normal versus abnormal facial development is cephalometric analysis Other measurements for assessing craniofacial developments are, head circumference, eye measurements, ear length and philtrum lengths, and widths of the commissures

Growth Assessment

Growth assessment is done to identify grossly abnormal or even pathologic growth, recognition and diagnosis of significant deviations from normal growth Planning orthodontic or orthopedic treatment and to determine the efficiency of the treatment.Growth assessment can be done by:

I Methods based on measuring animals:

1 Produces no interference with the animals, e.g Craniometry

2 Growth is manipulated—may be destructive, e.g Subhumans are used like guinea pigs

II Direct measurements:

1 Measurements done directly on the subjects

III Indirect measurements:

1 Measurements made on negative replicas of the original material, e.g X­rays

IV Three­dimensional facial measure­ments:

Growth prediction involves an understanding

of normal growth process On this possible

effects of orthodontic or orthopedic therapy

must be superimposed The starting point

for growth prediction must be an estimation

of growth changes that might occur without

orthodontic intervention The dimensions of

growth in which we are interested in predicting

the growth of craniofacial complex are the

following

The size of a part, relationship of parts,

timing of growth events, velocity of growth,

vectors of growth, effects of orthodontic

therapy on any one of the above parameters,

rate of growth and amount of growth

Growth predictions are usually guess work

based on the available data and individual

growth based on genetic pattern Actual

growth may or may not coincide with the actual

TYPES OF GROWTH DATA

The physical growth and development can be

studied by a number of ways

Opinion

Opinion is the crudest means of studying growth Opinion is a clever guess of an experienced person This method of studying growth is not very scientific and should be avoided when better methods are available

Ratings and Rankings

Whenever quantification of a particular data

is difficult, it is possible to adopt a method of rating and ranking

Rating makes use of standard conventionally accepted scales for classification Ranking involves the arrangement of data in an orderly sequence based on the value

Quantitative Measurements

A scientific approach to study growth is one that is based on accurate measurements The measurements made can be of three types

Direct data: Direct data are obtained from

measurements that are taken on living persons

or cadavers by means of scales measurement tapes or calipers

Indirect data: The growth measurements can

also be had from images or reproduction of the person such as photographs, radiographs

or dental casts

Derived data: They are data that are derived

after comparing two measurements These two sets of measurements can be of different time frames or of two different samples, e.g Mandible grew 2 mm between 7–8 years; here

we measure mandibular length at 7 years and

8 years to derive the value

Longitudinal study is a type of study where

measurements made of the same person of

group at regular intervals through time Thus

longitudinal studies are long­term studies

where the same sample is studied by means

of follow up examination

Advantages

Variability in development among individuals

within the group and developmental pattern

can be studied and compared

The specific pattern of an individual as

he develops can be studied, permitting serial

comparison with himself

Variations in sampling are smoothed out

with time and any unusual event or a mistake

in measuring at a given time is seen move easily

and corrections are made at the same time

Disadvantages

Time: If one wishes to study the growth of

human face from birth to adult by means of

longitudinal data it will take him a lifetime to

gather the data

Expense: Longitudinal studies necessitate

the maintenance of laboratories, research

personnel and data storage for a long time and

thus are costly

Attrition: The parents of children in long­

itudinal studies change their place, some

loose interest as a result; sample size gradually

reduces often reaches 50% in 15 years

Advantages

These studies are of short duration and faster.They are less expensive than longitudinal studies as they are completed in a shorter span

of time

It is possible to get a large sample, as the duration of study is short

It is possible to repeat the study in case

of any flaw This may not be possible with longitudinal study

This method is used for cadavers, skeletons and archeological data

Disadvantages

It must always be assumed that the groups being measured and compared are similar.Cross sectional group averages tend

to obscure individual variations This is particularly obfuscating when studying the timing of developmental events, for example the onset of pubescence or the adolescent growth spurt

Semi-longitudinal Studies (Overlapping Studies)

It is possible to combine the cross­sectional and longitudinal methods so as to derive the advantages of both the systems of gathering growth data

In this way one may compress 15 years

of study into 3 years of gathering data, each

subsample including children studied for the

same number of years, but started at different

ages

METHODS OF STUDYING GROWTH

Proffit lists two main methods of approaches

to studying physical growth and development,

they are:

Measurement approaches: They comprise of

measurement techniques that are carried out

on living individuals These methods do not

harm the animal

Experimental approaches: These are destructive

techniques where the animal that is studied is

sacrificed They are not usually carried out in

humans They are:

Biometric Tests

They are tests in which physical characteristics

such as weight; height, skeletal maturation and

ossification are measured and compared with

standards based upon the examination of large

groups of healthy subjects

Vital Staining

Belchier, in 1736 reported that bones of

animals that had eaten madder plants were

stained red In 1739 Duhamel fed madder

to animals and then with held it for a period

prior to sacrifice, as a result bone contained

a band of red stain followed by a unstained

band Subsequently the dye in the madder

plant, alizarin was identified and used for

bone research

This technique involves administration of

certain dyes to the experimental animal that

get incorporated in the bones It is possible to

study the manner in which bone is laid down, the site of growth, the direction, duration and amount of growth at different sites in bone Dyes used are Alizarin red S (Alizarin S sulphonate), Acid alizarin blue, Trypan blue, Tetracycline and Lead acetate The nature of the combination alizarin with bone is said

to be a chelation with divalent cation on the surface of the crystal Antibiotic tetracycline

is also vital bone marker

Radioisotopes

Radioisotopes of certain elements compounds when injected into tissue get incorporated

in the developing bone and act as in vivo

markers These radioisotopes can later be detected by tracking down the radioactivity they emit by means of Geiger counter or

by the use of autoradiographic techniques The radioisotopes used include: Technitium

33, Calcium 45, Potassium 32, and labeled components of proteins such as Tritiated proline

Implants

Bjork in 1969 first devised this method of implanting tiny bits of biologically inert alloys like tantalum into growing bones of animals

or human beings These serve as reference markers during serial radiographic analysis The metallic implants used for studying growth are usually very small, around 1.5 mm in length and 0.5 mm in diameter

The areas where the implants are placed in maxilla to study the growth are, hard palate, below the anterior nasal spine, in zygomatic process, border between hard palate and alveolar process medial to first molar In mandible they are placed in anterior aspect of symphysis, mandibular body, and or ramus in level with occlusal plane

Natural Markers

The persistence of certain developmental

features of bone has led to their use as natural

markers By means of serial radiography,

trabaculae, nutrient canals and lines of

arrested growth can be used for reference to

study deposition, resorption and remodeling

Comparative Anatomy

Certain basic principles of growth that are

universal to all species can first be studies on

laboratory animals, and later can be compared

with human growth

Radiographic Techniques

After Roentgen discovered X­rays different

radiographic techniques to study growth

and development were devised The most

commonly used techniques are:

Cephalometry: It is a standardized radio­

graphic technique of the craniofacial region

Serial cephalograms of the same patient over

a period of time gives the direction, amount of

growth Cephalometry makes possible to study

growth and valuable in orthodontic diagnosis,

planning and evaluation of treatment results

for growth prediction

Hand wrist X-rays: Radiographs of hand

wrist region are used to study the biological

or skeletal age of a person The hand wrist

region has a definite schedule of appearance

and ossification

Microradiography: A beam of X­rays at

the microscope level is passed through an

undecalcified thin section of bone or tooth

that has been placed over a sensitive emulsion

The differential passage of the rays through

the different areas of the tissue section is

recorded on the film as varying blacks, grays

and whites

Genetic Studies

Genetic methods currently being used are

to study of parent­child relationship, sibling similarities and twin studies

MECHANISM OF BONE GROWTH

Bone is a specialized tissue of mesodermal origin It forms the structural framework of the body Bone is a calcified tissue that supports the body and gives areas of attachment to musculature Body has 206 bones of which 22 are in the skull; of which 14 bones are facial bones and 8 are skull bones, but at birth skull has 45 bones Bone contains between 32–36%

of organic matters

Skull bones are:

Cranial base bones: Frontal, ethmoid,

sphenoid and occipital

Cranial vault bones (Paired): Parietal­2 and

temporal­2

Facial bones are:

Paired bones: Maxilla, nasal, lacrimal,

zygomatic, inferior nasal concha and palatine bone

Unpaired bones: Vomer and mandible.

OSTEOGENESIS (MECHANISM OF BONE FORMATION)

The process of bone formation is called osteo­genesis Bone formation takes place in two ways:

Endochondral Bone Formation (Flow chart 2.1)

In this type of osteogenesis the bone formation

is preceded by formation of a cartilaginous

model, which is subsequently replaced by

bone Endochondral bone formation occurs

as follows:

Mesenchymal cells condensed at the site

of bone formation, some mesenchymal cells

differentiate into chondroblasts and lay down

hyaline cartilage, the cartilage is surrounded

by a membrane called perichondrium This is

highly vascular and contains osteogenic cells

The intercellular substance surrounding the

cartilage cells becomes calcified due to the

influence of enzyme alkaline phosphatase

secreted by the cartilage cells Thus the nutri­

tion to the cartilage cells is cut off leading

to their death These results in formation of

empty spaces called primary areolae The

blood vessels and osteogenic cells from the

perichondrium invade the calcified cartilagi­

nous matrix, which now reduced to bars

or walls due to eating away of the calcified

matrix This leaves large empty spaces between

the walls called secondary areolae The

osteogenic cells from the perichondrium

become osteoblasts and arrange themselves

along the surface of these bars of calcified

matrix The osteoblasts lay down osteoid that

later becomes calcified to form lamella of

bone Now another layer of osteoid is secreted and this goes on and on Thus the calcified matrix of cartilage acts as a support for bone formation

It is found in the bones associated with movable joints and some parts of cranial base

Intramembranous Bone Formation (Membranous Bone Formation) (Flow chart 2.2)

In this type of ossification, the formation

of bone is not preceded by formation of a cartilaginous model Instead bone is laid down directly in a fibrous membrane The intramembranous bone is formed in the following manner:

At the site of bone formation mesenchymal cells become aggregated, some mesenchymal cells lay down bundles of collagen fibers Some mesenchymal cells enlarge and acquire a basophilic cytoplasm and form osteoblasts These osteoblasts secrete a gelatinous matrix called osteoid around the collagen fibers They deposit calcium salts into the osteoid leading to conversion of osteoid into bone lamella Now the osteoblasts move away from the lamella and a new layer of osteoid is secreted which also

Flow chart 2.1: Endochondral bone formation Flow chart 2.2: Intramembranous bone formation

gets calcified Some of the osteoblasts get

entrapped between two lamellae they are

called osteocytes

Bone growth in intramembranous is only

appositional, bone grows in the direction of

least resistance and soft tissue dominates bone

growth

Mechanism of bone growth can be cate­

gori zed into:

Bone Deposition and Resorption

(Bone Remodeling)

Bone changes in shape and size by two basic

mechanisms, bone deposition and bone

resorption The process of bone deposition and

resorption together is called bone remodeling

Changes that are produced due to deposition

and resorption are, change in size, change

in shape, change in proportion, change in

dimensions, change in relationship of the bone

with adjacent structures

Growth Movements

Two basic movements involved during growth

are growth drift and displacement

Drift (Cortical Drift) (Fig 2.6)

Direct deposition and resorption of bone tissue

and characteristic combinations of deposition

and resorption occurring in the different

bones of the skull result in growth movements

towards depository surface is termed drift If

bone deposition and resorption on either side

of a bone are equal, then the thickness of the

bone remains constant If in case more bone is deposited on one side and less bone resorbed

on the opposite side then the thickness of the bone increases Drift occurs in all areas

of growing bones, and produces generalized enlargement as well as relocation of parts

Displacement

It is the movement of the whole bone as a unit It is as a result of the pull or push by different bones and their soft tissues away from one another as they all continue to enlarge Displacement can be primary or secondary

Primary displacement: If a bone gets disp­

laced as a result of its own growth, it is called primary displacement For example growth

of maxilla at the tuberosity region results in pushing of the maxilla against the cranial base that results in the displacement of the maxilla

in a forward and downward directions

Secondary displacement: If the bone gets

displaced as a result of growth and enlargement

of adjacent bones, it is called secondary displacement For example, the growth of the cranial base causes the forward and downward displacement of the maxilla

Overall process of craniofacial enlargement

is a composite of drift and displacement

Directions of Growth

Surfaces oriented towards the actual direction

of growth undergo new bone deposition, whereas surfaces directed away from the course of growth generally are resorptive.For example, posterior border of ramus

is depository and anterior border of ramus is resorptive

Soft Tissues Associated with Growth

The soft tissue matrix of bone is directly respon sible for many of the growth changes that occur in the bone itself

Figure 2.6: Drift

Growth Fields

The areas capable of producing an alteration

in the growth of the particular bone are called

growth fields They are mosaic like patterns

of soft tissues, cartilage or osteogenetic

membrane

Growth Sites

Growth sites are growth fields that have

a special significance in the growth of a

particular bone, e.g maxillary tuberosity

Growth Centers

Growth centers are special growth sites,

which control the overall growth of bone, e.g

epiphyseal plates of long bones

THEORIES OF GROWTH

Genetic Theory

This theory simply states that all growth and

development is controlled by genetic influence

and is preplanned This is one of the earliest

theories put forward

Sutural Theory (Sicher) (Fig 2.7)

Sicher believed that craniofacial growth occurs

at the sutures According to him paired parallel

sutures that attach facial areas to the skull and

the cranial base region push the nasomaxillary

complex forwards to pace its growth with that

of the mandible This theory also acknowledges the genetic influence of growth

A number of points were raised against this theory The following are some of them: When an area of the suture is transplanted

to another location, the tissue does not continue to grow This clearly indicates a lack

of innate growth potential of the sutures Growth takes place in untreated cases of cleft palate even in the absence of sutures Microcephaly and hydrocephaly raised doubts about the intrinsic genetic stimulus of sutures

Cartilaginous Theory (James Scott) (Fig 2.8)

This theory was put forward by James Scott According to him intrinsic growth controlling factors are present in cartilage and periosteum with sutures being only secondary He viewed the cartilaginous sites throughout the skull as primary centers of growth

Growth of the maxilla is attributed to the nasal septal cartilage According to Scott, the nasal septal cartilage is the pacemaker for growth of the entire nasomaxillary complex The mandible is considered as the diaphysis of

a long bone, bent into a horseshoe shape with symphysis removed so that there is cartilage

Figure 2.7: Sutural theory of growth Figure 2.8: Cartilaginous theory

constituting half an epiphyseal plate at the

ends that are represented by the condyles

Points in favor of this theory include:

In many bones, cartilage growth occurs,

while bone merely replaces it

If a part of an epiphyseal plate is transpl­

anted to a different location, it will continue

to grow in the new location This indicates the

innate growth potential of the cartilage

Nasal septal cartilage also shows innate

growth potential on being transplanted to

another site

Experiments on rabbits involving removal

of the nasal septal cartilage demonstrated

retarded midface development

In cleft palate where midface is deficient

growth is taking place

Functional Matrix Theory

(Melvin Moss) (Fig 2.9)

The functional matrix concept of Melvin

Moss revitalized the studies on growth and

development at a time when the sutural

growth theory of Sicher and cartilaginous

growth theory of Scott were severely criticized

for their inadequacy Moss introduced the

doctrine of functional matrix complimentary

to the original concept of functional cranial

components by Van der Klaaw, the functional

matrix concept attempts to comprehend the

relationship between form and function

The functional matrix hypothesis claims that the origin, form, position growth and maintenance of all skeletal tissues and organs are always secondary, compensatory and necessary responses to chronologically and morphologically prior events or processes that occur in specifically related nonskeletal tissues, organs or functioning spaces

A number of relatively independent functional are carried out in the craniofacial region of the human body Some of the functions carried out include respiration, olfaction, vision, hearing, balance, chewing, digestion, swall owing, speech and neural integration

Each of these functions is carried out by a functional cranial component Each functional cranial component consists of all of the tissues, organs, spaces and skeletal parts necessary

to carry out a given function The functional cranial component is divided into:

Functional Matrix and Skeletal Units

All the tissues, organs and functioning spaces taken as a whole comprise the functional matrix, while the skeletal tissues related to this specific functional matrix comprise the skeletal unit All skeletal tissues originate, grow and function completely embedded in their several matrices Thus change in size, shape and spatial position of all skeletal units including their very maintenance is due to the operational activity of their related functional matrices

The skeletal unit: All skeletal tissues asso­

ci ated with a single function are called

‘the skeletal unit’; the skeletal unit may be comprised of bone, cartilage and tendinous tissue When a bone is comprised of several contiguous skeletal units, they are termed

‘microskeletal units’ The maxilla and mandible are comprised of a number of such microskeletal units For example, the mandible

Figure 2.9: Functional matrix theory

has within it alveolar, angular, condylar, gonial,

mental, coronoid, and basal microskeletal

units In case of maxilla it is made up of orbital,

pneumatic, palatal and basal microskeletal

units When adjoining portions of a number

of neighboring bones are united to function

as a single cranial component, we term this

a ‘macroskeletal unit’ The entire endocranial

surface of the calvarium is an example of a

macro s keletal unit

The functional matrix: The functional matrix

consists of muscles, glands, nerves, vessels,

fat, teeth and the functioning spaces The

functional matrix is divided into periosteal

matrix and capsular matrix

Periosteal matrices act directly and actively

upon their related skeletal units Alterations

in their functional demands produce a seco­

ndary compensatory transformation of the

size and or shape of their skeletal units Such

transformations are brought about by the

interrelated processes of bone deposition

and resorption The periosteal matrices

include the muscles, blood vessels, nerves,

glands, etc These tissues act directly on their

related skeletal units thereby bringing about

a transformation in their size and shape This

transformation due to the action of periosteal

matrices is brought about by bone deposition

and resorption

Capsular matrices act indirectly and passi­

vely on their related skeletal units producing a

secondary compensatory translation in space

These alterations in spatial position of skeletal

units are brought about by the expansion of the

orofacial capsule within which the facial bones

arise, grow and are maintained The facial

skeletal units are passively and secondarily

moved in space as their enveloping capsule is

expanded The kind of translative growth is not

brought about by deposition and resorption

The neurocranial capsule and the orofacial

capsule are examples of capsular matrices Each

of these capsules is an envelop which contains

a series of functional cranial components (skeletal units and related functional matrices) which as a whole are sandwiched in between two covering layers In the neurocranial capsule, the covers consist of the skin and dura mater where as in the orofacial capsule the skin and mucosa form the covering

The neurocranial capsule surrounds and protects the neurocranial capsular functional matrix that is the brain, leptomeninges, and Cerebrospinal fluid The neurocranial capsule is made up of skin, connective tis­sue, aponeurotic layer, loose connective tissue layer, periosteum, and base of the skull and the two layers of dura mater The orofacial capsule surrounds and protects the oronasopharyngeal spaces, which constitute the orofacial capsular matrix The growth of the facial skull is influenced by the volume and patency of these spaces

van Limbourgh’s Theory

A multifactorial theory was put forward

by van Limbourgh in 1970 According to him the three popular theories of growth were not satisfactory, yet each contains elements of significance that cannot be denied van Limbourgh explains the process

of growth and development in a view that combines all the three existing theories He supports the functional matrix theory of Moss, acknowledges some aspects of Sicher’s theory and at the same time does not rule out genetic involvement van Limbourgh listed five factors that he believed controls growth

Intrinsic genetic factors: They are the genetic

control of the skeletal units themselves

Local epigenetic factors: Bone growth is

determined by genetic control originating from adjacent structures like brain, eyes, etc

General epigenetic factors: They are genetic

factors determining growth from distant

structures, e.g Sex hormone, growth hormone,

etc

Local environmental factors: They are non ­

genetic factors from local external environment,

e.g Habits, muscle force, etc

General environmental factors: They are gen­

eral nongenetic influences such as nutrition,

oxygen, etc

The views expressed by van Limbourgh can

be summarized as following:

Chondrocranial growth is controlled

mainly by the intrinsic genetic factors

Desmochondral growth is controlled by

any few intrinsic genetic factors

The cartilaginous parts of the skull must be

considered as growth centers

Sutural growth is controlled mainly by

influences originating from the skull cartilages

and from other adjacent skull structures

Periosteal growth largely depends upon

growth of adjacent structures

Sutural and periosteal growths are add­

iti onally governed by local nongenetic

environmental influence

Enlow and Bang’s Expanding ‘V’

Principle (Fig 2.10)

Many facial bones or parts of bone have a

‘V’ shaped pattern of growth The growth

movements and enlargement of these bones

occur towards the wide ends of the ‘V’ as a

result of differential deposition and selective

resorption of bone Bone deposition occurs

on the inner side of the wide end of the

‘V’ and bone resorption on the outer surface

(Fig 2.11)

Deposition also takes place at the ends

of the two arms of the ‘V’ resulting in growth

movement towards the ends

The ‘V’ pattern of the growth occurs in

a number of regions such as the base of the

mandible, ends of long bones, mandibular

body, palate, etc

Figure 2.10: ‘V’ principle of growth

Figure 2.11: ‘V’ principles—deposition and resorption

Neurotrophic Process in Orofacial Growth (Neurotrophism)

Neurotrophism is a nonimpulse transmitting neural function that involves axoplasmic