Introduction to the Masticatory System and Dental Occlusion

The Author Dinesh Rokaya, PhD is a Visiting Professor at the Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.

• About the Author xiiiForeword xivForeword 2 xvForeword 3 xviPreface xviiAcknowledgments xviii1 Structures and Functions of Masticatory System 11.1 Introduction 11.2 Structures and Functions of Temporomandibular Joint 11.2.1 Articular Surfaces 11.2.2 Ligaments 11.2.2.1 Collateral (Discal) Ligaments 21.2.2.2 Capsular Ligament 31.2.2.3 Temporomandibular Ligament 31.2.2.4 Sphenomandibular Ligament 41.2.2.5 Stylomandibular Ligament 41.2.3 Nerve Innervation of the Temporomandibular Joint 51.2.4 Blood Supply of the Temporomandibular Joint 51.2.5 Functions of the Temporomandibular Joint 51.2.6 Clinical Evaluation of the Temporomandibular Joint 51.2.7 Radiographic Examination of the Temporomandibular Joint 51.2.8 Clinical Considerations of the Temporomandibular Joint 71.3 Structures and Functions of Masticatory Muscles 71.3.1 Temporalis 81.3.2 Masseter 111.3.3 Medial Pterygoid 111.3.4 Lateral Pterygoid 121.3.5 Accessory Muscles of Mastication 141.3.6 Clinical Considerations of the Muscles of Mastication 151.4 Structures and Functions of Teeth and Associated Structures 151.5 Biomechanical Interaction Between Masticatory Muscles and Bones 17References 192 Intra-arch Tooth Alignment 222.1 Introduction 222.2 Maxillary and Mandibular Arch 222.2.1 Arch Form 222.2.2 Arch Length 242.2.3 Arch Width 242.2.4 Arch Circumference 252.3 Planes of Occlusion 252.3.1 Curve of Spee 252.3.2 Curve of Wilson 262.3.3 Sphere of Monsoon 262.4 Buccolingual Occlusal Contact Relationship 262.4.1 Bucco-occlusal Line 272.4.2 Linguo-occlusal Line 272.4.3 Central Fossa Line 272.5 Mesio-Distal Relationship and Buccolingual Embrasure 282.6 Proximal (Interproximal) and Occlusal Contacts 292.7 Functional Form of the Teeth at their Incisal and Occlusal Thirds 292.8 Inclination and Angulations of Individual Teeth 31References 323 Inter-arch Tooth Alignment 363.1 Introduction 363.2 Dental Occlusion 363.3 Overjet and Overbite 373.4 Centric and Noncentric Cusps 393.5 Common Occlusal Relationships 403.5.1 Molar Classification 403.5.2 Canine Classification 423.5.3 Incisor Classification 433.6 Position of Mandible and Condyle 443.6.1 Centric Relation 443.6.2 Centric Occlusion 443.6.3 Vertical Dimension of Occlusion 453.6.4 Vertical Dimension of Rest 453.6.5 Freeway Space 453.7 Terminal Hinge Axis Position and Retruded Contact Position 463.8 Working and Nonworking (Balancing) Side 463.9 Tooth Guidance 473.9.1 Anterior or Lateral Guidance 473.9.1.1 Sagittal Protrusive Incisal Path Inclination 483.9.1.2 Lateral Incisal Path Inclination 493.9.2 Canine Guidance 493.10 Tooth Contacts 503.10.1 Protrusive Contacts 503.10.2 Retrusive Contacts 503.11 Occlusal Contact and Stability 51References 524 Occlusal Surface of Teeth and Characteristics of Jaw Movement 544.1 Introduction 544.2 Posterior Controlling Factors (Condylar Guidance) 544.3 Anterior Controlling Factors (Anterior Guidance) 554.4 Vertical Determinants of Occlusal Morphology 564.4.1 Effect of Condylar Guidance on Cusp Height 564.4.2 Effect of Anterior Guidance on Cusp Height 564.4.3 Effect of Occlusion Pane on Cusp Height 564.4.4 Effect of Curve of Spee on Cusp Height 574.4.5 Effect of Mandibular Lateral Translation Movement on Cusp Height 604.4.5.1 Effect of the Amount of Lateral Translation Movement on Cusp Height 614.4.5.2 Effect of the Direction of the Lateral Translation Movement on Cusp Height 614.4.5.3 Effect of the Timing of the Lateral Translation Movement on Cusp Height 634.5 Horizontal Determinants of Occlusal Morphology 634.5.1 Effect of Distance from the Condyle on Ridge and Groove Direction 654.5.2 Effect of Distance from the Midsagittal Plane on Ridge and Groove Direction 654.6 Relationship Between Anterior and Posterior Controlling Factors 66References 665 Mandibular Movements 685.1 Introduction 685.2 Mandibular Movements 685.2.1 Rotational Movements 705.2.1.1 Horizontal Axis of Rotation 705.2.1.2 Vertical Axis of Rotation 715.2.1.3 Sagittal Axis of Rotation 725.2.2 Translational Movements 725.2.2.1 Range of Movements 735.3 Single Plane Border Movements 735.3.1 Sagittal Plane Border and Functional Movements 735.3.1.1 Posterior Opening Border Movements 735.3.1.2 Anterior Opening Border Movements 745.3.1.3 Superior Contact Border Movements 745.3.1.4 Functional Movements 765.3.2 Horizontal Plane Border and Functional Movements 775.3.2.1 Right Lateral Border Movements 775.3.2.2 Continued Right Lateral Border Movements with Protrusion 775.3.2.3 Left Lateral Border Movements 775.3.2.4 Continued Left Lateral Border Movements with Protrusion 795.3.2.5 Functional Movements 795.3.3 Vertical Plane Border Movements and Functional Movements 795.3.3.1 Right Lateral Superior Border Movements 795.3.3.2 Right Lateral Opening Border Movements 805.3.3.3 Left Lateral Superior Border Movements 805.3.3.4 Left Lateral Opening Border Movements 805.3.3.5 Functional Movements 805.4 Envelope of Motion 805.5 Mandibular Movements in Diseases and Defects 82References 856 Mastication, Swallowing, and Speech 876.1 Introduction 876.2 Mastication 876.2.1 Masticatory Mechanism and Chewing Stroke 886.2.2 Incision of Food 886.2.3 Crushing and Grinding of Food 886.2.4 Masticatory Cycle 886.2.4.1 Phase 1: Opening 896.2.4.2 Phase 2: Closing 906.2.4.3 Phase 3: Occlusion 906.2.4.4 Phase 4: Exit 916.2.5 Mandibular Movements During Crushing and Grinding 916.2.6 Chewing Side Preference 936.2.7 Contacts of Tooth During Mastication 936.2.8 Mastication Force 936.3 Swallowing 946.3.1 First Stage 966.3.2 Second Stage 986.3.3 Third Stage 986.3.4 Swallowing Frequency 1006.3.5 Teeth Contact During Swallowing 1016.4 Speech 101References 1037 Nervous System Regulating the Masticatory System 1077.1 Introduction 1077.2 Anatomy and Function of the Neuromuscular System 1077.2.1 Neurologic Structures 1077.2.1.1 The Neuron 1077.2.1.2 Sensory Receptors 1087.2.1.3 Brainstem and Brain 1097.2.1.4 Spinal Tract Nucleus 1097.2.1.5 Reticular Formation 1097.2.1.6 Thalamus 1097.2.1.7 Hypothalamus 1097.2.1.8 Limbic Structures 1107.2.1.9 Cortex 1107.2.2 Muscles 1107.2.2.1 Motor Unit 1107.2.2.2 Muscle Function 1107.2.2.3 Muscle Sensory Receptors 1127.2.2.4 Muscle Spindles 1127.2.2.5 Golgi Tendon Organs 1137.2.2.6 Pacinian Corpuscles 1137.2.2.7 Nociceptors 1137.3 Neuromuscular Function 1137.3.1 Function of the Sensory Receptors 1137.3.2 Reflex Action 1147.3.3 Nociceptive (Flexor) Reflex 1147.3.4 Myotatic (Stretch) Reflex 1157.3.5 Reciprocal Innervation 1157.4 Aging of the Neuromuscular System and Performance 116References 1188 Bruxism and Clenching 1218.1 Introduction 1218.2 Bruxism 1218.2.1 Types of Bruxism 1218.2.2 Causes and Risk Factors 1218.2.3 Pathophysiology 1228.2.4 Clinical Features 1248.2.5 Management 1258.3 Clenching 1298.3.1 Clinical Features 129References 1309 Aging-Related Changes of Masticatory System 1339.1 Introduction 1339.2 Effect of Aging on Mastication 1359.2.1 Dentation 1359.2.2 Salivation 1369.3 Effect of Aging on Masticatory Muscles 1379.4 Effect of Aging on Swallowing 1389.5 Effect of Aging on Temporomandibular Joint 1389.6 Effect of Aging on the Muscles and Nerves 139References 14010 Occlusal Concept and Its Application in Various Fields 14410.1 Introduction 14410.2 Articulators 14410.3 Occlusal Concept Application Restorative Dentistry 14810.3.1 Treatment Goals for Tooth Contacts 14810.3.2 Treatment Goals for the Mandibular Position 14810.4 Occlusal Concept Application in Fixed Prosthodontics 14910.4.1 Treatment Goals for Tooth Contacts 14910.4.2 Treatment Goals for the Mandibular Position 15010.5 Occlusal Concept Application in Implant Dentistry 15110.6 Occlusal Concept Application in Periodontics 15110.7 Occlusal Analysis and Adjustments 153References 15611 Problems in Occlusion 15911.1 Introduction 15911.2 Complete Dentistry 15911.3 Treatment of Occlusal Problems 16011.3.1 Accomplishing Treatment Goals in Operative Dentistry 16011.3.1.1 Contacts in Anterior Teeth 16011.3.1.2 Contacts in Posterior Teeth 16011.3.2 Accomplishing Treatment Goals in Fixed Prosthodontics 16211.3.2.1 Contacts in Anterior Teeth 16211.3.2.2 Contacts in Posterior Teeth 16211.3.3 Selective Grinding 162References 169Index 171