Essentials of Orthodontics

Preface xiii

Acknowledgments xv

Introduction xvii

Chapter 1 Orthodontic Diagnosis and Treatment Planning 3

Normal and Ideal Occlusion 3

Normal Occlusion in the Primary Dentition 4

Centric Occlusion and Centric Relation 5

Angle Classification of Malocclusion 6

Angle Class I Malocclusion 6

Class I Malocclusions in the Primary and Mixed Dentitions 7

Angle Class II Division 1

Malocclusion 7

Angle Class II Division 2

Malocclusion 8

Class II Malocclusions in the Primary and Mixed Dentitions 8

End-to-End Occlusion 8

Angle Class III Malocclusion 9

Class III Malocclusions in Primary and Mixed Dentitions 9

Super Class I Malocclusions 9

Super Class II and Super Class III Malocclusions 9

Subdivision Malocclusions 9

Class II Subdivision Malocclusions 9

Class III Subdivision Malocclusions 9

Class II-III Subdivision Malocclusions 10

Incisor Dental Compensations in Class II and Class III Malocclusions 10

Iowa Notation System for Angle Classification 10

Rules for Assigning Angle Classification 10

Rating the Severity of a Malocclusion 11

Orthodontic Records 11

Clinical Examination 12

Summary of Findings, Problem List, and Diagnosis 16

Consultation with Patient and/or Parent 17

Chapter 2 Dental Impressions and Study Cast Trimming 19

Study Casts 19

Digital Casts 19

Alginate Impressions 20

Mandibular Impression 20

Maxillary Impression 21

Record of Centric Occlusion 21

Pouring of Plaster Study Casts 22

Study Cast Trimming 22

Chapter 3 Dental Cast Analysis in Adults 33

Tooth SizeArch Length Analysis 33

Measurement of Tooth Size and Arch Length 33

Factors Influencing a Tooth SizeArch Length Analysis 34

Curve of Spee 34

Incisor Inclination and Anteroposterior Position 36

Second and Third Molar Evaluation 36

Comparison of TSALD Analysis and the Irregularity Index 37

Arch Width Measurements 37

Diagnostic Setup 38

Bolton Analysis 38

Overbite and Overjet Measurements 40

Mandibular Crowding 42

Tooth Widths in Normal Occlusion 42

Chapter 4 Dental Cast Analysis in the Mixed Dentition 43

Tooth SizeArch Length Analysis 43

Prediction of the Widths of Nonerupted Canines and Premolars 44

Radiographic Enlargement of Nonerupted Canines and Premolars 45

Revised Hixon-Oldfather Prediction Method 45

Iowa Prediction Method for Both Arches 48

Upper Arch 48

Lower Arch 48

Standard Error of Estimate 48

Radiograph Image Problems 53

Proportional Equation Prediction Method 53

Tanaka and Johnston Prediction Method 54

Measurement of Arch Lengths on Casts 54

Measurement Instruments and Guidelines 55

Factors that Influence a Mixed-Dentition Arch Length Analysis 55

Interpretation of a Mixed- Dentition Arch Length Analysis 55

Chapter 5 Radiographic Analysis 57

Periapical Survey 57

Panoramic Radiograph 57

Occlusal Radiographs 61

Cone Beam Radiographs 62

Lateral Cephalometric Radiographs 64

Anatomic Landmarks 65

Cephalometric Landmarks 65

Cephalometric Point Locations 66

Cephalometric Planes 67

Cephalometric Angles and Distances 68

Skeletal Angles and Distances 68

Dental Angles 69

Distances of Incisors to Anterior Vertical Lines 69

Cephalometric Norms and Treatment Goals 71

Lateral Cephalometric Tracing 71

Posteroanterior Cephalometric Radiograph 72

Analog versus Digital Radiography 73

Chapter 6 Lingual and Palatal Arches 75

Incisor Liability and Leeway Space 75

Passive Lower Lingual Holding Arch 75

Prevalence of Incisor Crowding 76

Premature Loss of a Primary Molar 77

Asymmetric Loss of a Primary Canine 78

Nance Holding Arch 79

Trans-palatal Arch 82

Insertion of a Passive Lingual or Palatal Arch 83

Fixed-Removable Lingual and Palatal Arches 84

Undesirable Side Effects of Passive and Active Lingual and Palatal Arches 86

Laboratory Prescription and Construction of a Lower Loop Lingual Arch 87

Failure of a Lower Lingual Arch 92

Chapter 7 Management of Anterior Crossbites 95

Prevalence of Anterior Crossbite Malocclusions 95

Angle Classification 96

Centric Relation to Centric Occlusion Functional Shift on Closure 96

Overbite 96

Adequate Arch Length 96

Inclination of Maxillary Incisor Roots 97

Rotation of Tooth in Crossbite 97

Number of Teeth in Crossbite 97

Alignment of Lower Anterior Teeth 97

Treatment of Anterior Crossbites with Removable Appliances 97

Treatment of Anterior Crossbites with Fixed Appliances 102

Construction of a Removable Maxillary Appliance to Close a Diastema and Correct a Lateral Incisor in Crossbite 104

Chapter 8 Management of Posterior Crossbites 113

Definition of Posterior Crossbite 113

Prevalence of Posterior Crossbite Malocclusions 113

Angle Classification 114

Intermolar Width Measurements 114

Age of Patient 114

Buccolingual Inclination of the Posterior Teeth 114

Etiology of Bilateral and Unilateral Posterior Crossbites 115

Vertical Dimension 116

Treatment of Posterior Crossbites 116

Correction of Posterior Crossbites with Removable Appliances 116

Correction of Posterior Crossbites with Fixed Expander Appliances 123

Chapter 9 Management of Incisor Diastemas 135

Prevalence of Maxillary Diastemas 135

Etiologic Factors to Consider 135

Size of Teeth and Bolton Analysis 136

Arch Size 137

Maxillary Labial Frenum 137

Rotated Incisors 138

Thumb-Sucking Habit 138

Angle Classifi cation 139

Management with Appliances 139

Treatment of a Diastema with a Removable Loop Spring Appliance 139

Treatment of a Diastema with a Finger Spring Removable Appliance 141

Treatment of a Diastema Caused by a Thumb Habit 143

Treatment of a Diastema with the Edgewise Fixed Appliance 144

Chapter 10 Molar Uprighting and Space Regaining 151

Introduction 151

Ectopic Eruption of Permanent First Molars 151

Uprighting Molars in the Mixed Dentition 153

Ectopic Eruption of Upper First Molars 153

Ectopic Eruption and Tipping of Lower First Molars 158

Mesial Tipping of Permanent Molars after Loss of a First Molar 162

Prevention of Molar Tipping after Loss of a First Molar 164

Impaction of Second Molars 164

Loss of Both First and Second Molars 165

T-Loop Uprighting Spring and Edgewise Fixed Appliance 165

Forces Generated by the T-Loop Uprighting Spring 167

Patient Treated with a T-Loop Uprighting Spring 168

Helical Uprighting Spring 169

Forces Generated by the Helical Uprighting Spring 171

Patient Treated with a Helical Uprighting Spring 171

Other Appliances Used to Upright Molars 172

Repositioning of Teeth Prior to Prosthetic Restoration 172

Chapter 11 Orthodontic Examination and Decision Making for the Family Dentist 177

Introduction 177

Orthodontic Screening 178

Guidelines for Orthodontic Decision Making 179

Problems 180

Pretreatment Records 180

Patient 1 181

Patient 2 182

Patient 3 184

Patient 4 186

Patient 5 187

Patient 6 189

Patient 7 190

Patient 8 192

Patient 9 193

Treatment Records 195

Patient 1 195

Patient 2 196

Patient 3 198

Patient 4 200

Patient 5 202

Patient 6 204

Patient 7 206

Patient 8 208

Patient 9 210

Chapter 12 How Orthodontic Appliances Move Teeth 213

Introduction 213

Biomechanics 216

Newtons First Law 218

Newtons Second Law 219

Keys to Understanding the Delivery of Orthodontic Forces 219

General Displacements of Rigid Bodies: Euler and Chasles 221

Limitations of Illustrating Three-Dimensional Tooth Movements in Two- Dimensional Figures 221

Translation of a Tooth in the Edgewise Fixed Appliance 222

How a Tooth Is Translated in the Edgewise Fixed Appliance 222

Rotation of a Tooth in the Edgewise Fixed Appliance 225

Newtons Third Law 226

Chapter 13 The Edgewise Fixed Appliance 229

Introduction 229

The Edgewise Appliance 229

Arch Wires 230

Bands 231

Separators 231

Fitting a Band 231

Cementing a Band 231

Band Cements 232

Removal of Bands 232

Bonding of Brackets 232

Anatomic Considerations 233

The Straight Wire Appliance 234

Bracket and Molar Tube Placement 234

Direct and Indirect Bonding 236

Removal of Brackets and Bonded Attachments from Teeth 236

Arch Form 236

Chapter 14 Retention Appliances 239

Introduction 239

Fixed Retainers and Tooth Positioners 239

Invisible Retainers 243

Essix Retainers 249

Basic Retainer Design 251

Wire-Bending Skills 252

Maxillary Labial Bow Bending 254

Ball Clasp 267

C-Clasp 271

Adams Clasp 271

ReSta Clasp 285

Mandibular Labial Bow 294

Acrylicing Retainers 301

Acrylic Finishing and Polishing 307

Chapter 15 Orthodontic Materials 317

Introduction 317

Orthodontic Wires 317

Stainless Steel Wires 317

Sensitization 317

Cold Working 318

Recovery Heat Treatment 319

Annealing 319

Cobalt-Chromium-Nickel Wires 319

Beta-Titanium Wires 320

Nickel-Titanium Wires 320

Physical Properties of Orthodontic Wires 320

Wire Sizes 322

Electric Welding 323

Flame Soldering 324

Electric Soldering 324

Index 327