Chapter 9: Functional Occlusion and Malocclusion

I. Ideal Occlusion Versus Malocclusion Ideal Class I Occlusion Dental Malocclusions of Teeth (Including Class I) Class II Malocclusion Class III Malocclusion

A. Ideal Class I Occlusion (Normal or Neutroclusion)

Normal Overjet (Horizontal Overlap)

Normal Overbite (Vertical Overlap)

Ideally, Buccal Cusps of Maxillary Teeth are Positioned More Buccal than Buccal Cusps of Mandibular Teeth

Ideally, Maxillary Teeth are Positioned Slightly Distal to their Corresponding Mandibular Teeth

B. Dental Malocclusions of Teeth: Crowding Where Tooth #24 is in Labioversion; #7 and 10 are in Linguoversion

Dental Malocclusion: Tooth #8 is Rotated, in Torsiversion

Dental Malocclusion: Tooth #1 is Supraerupted or Extruded, in Supraversion; Also, Facets on Mandibular Cusps Indicate Heavy Occlusion

Dental Malocclusion: Posterior Teeth are in Crossbite because the Buccal Surfaces of Mandibular Teeth are Positioned more Buccal than Maxillary Buccal Surfaces

Dental Malocclusion: Posterior Teeth are Almost in a Type of Crossbite where Lingual Cusps of Maxillary Posterior Teeth Do Not Fit in the Opposing Fossa but are Buccal to (here are even with) the Mandibular Buccal Cusps

Anterior Dental Malocclusion: Anterior Teeth are in Crossbite Since the Mandibular Incisors are Labial to the Maxillary Incisors

Anterior Dental Malocclusion: Anterior Teeth are in a Deep Overbite Relationship Since the Maxillary Incisors Completely Overlap (Vertically) the Mandibular Incisors

Anterior Dental Malocclusion: Anterior Teeth are in an Edge-to-Edge Relationship Since the Incisal Edges of Both Arches Line Up

Anterior Dental Malocclusion: Anterior Teeth are in an Open-bite Relationship Since the Incisal Edges of Both Arches Do Not Touch or Overlap Vertically when All Posterior Teeth are in Contact

Anterior Dental Malocclusion: Anterior Teeth are in an Over-jet Relationship Since the Maxillary Incisors are Considerably Anterior to (Horizontal Overlap), and Not Occluding with, the Mandibular Incisors

C. Class II Malocclusion (Distal Occlusion)

Class II Malocclusion with Anterior Overjet

Class II Malocclusion, Division II, Often Exhibits Deep Overbite with Maxillary Central Incisors Tipped Lingually but Laterals Tipped Labially

Class II Malocclusion, Division I, May Exhibit Considerable Overjet (Often with All Maxillary Incisors Tipped Labially)

D. Class III Malocclusion

Class III Malocclusion: The Anterior Relationship is Often Edge to Edge or in Crossbite

Class III Malocclusion Profile

II. Normal Movements Within the Temporomandibular Joint (TMJ) Anatomy of the Temporomandibular Joint (TMJ) Movements within the Lower Joint Space (Hinge, Rotary Movement with Minimal Opening) Movements within the Upper Joint Space (Sliding, Translating, Bodily Movement when Open Wide) Total Joint Movement (Ginglymoarthrodial = Rotates and Translates) Dislocation of the Mandible

A. The TMJ: Articular Eminence and Fossa of Temporal Bone, and Mandibular Condyle

The TMJ: Inferior view of the Articular Eminence and Fossa of the Temporal Bone, and the Mandibular Condyle

The TMJ: Cross Section of the Articular Eminence and Fossa, and Mandibular Condyle with Stress Bearing, Fibrous Areas in Red

The TMJ: Articular Eminence and Fossa, Upper (Synovial) Joint Space, Disc, Lower (Synovial) Joint Space, and Mandibular Condyle

The TMJ: The Limiting, Surrounding Fibrous Capsule

B. Movements within the Lower Joint Space: Is Hinge Type or Rotational Occurring with Minimal Mouth Opening

C. Movements within the Upper Joint Space: Is Translational where the Mandible Moves (Translates) Bodily Forward when Opening the Mouth Wide

E. Dislocation of the Mandible

III. Terms Used to Describe Jaw Relationships between the Mandible to the Maxillae A. Maximal Intercuspal Position B. Centric Relation C. Physiologic Rest Position D. Jaw Relations During Horizontal Movements of the Mandible

A. Maximum Intercuspal Position (MIP) of Handheld Casts Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

B. Centric Relation: The Anterior-superior Surface of Mandibular Condyle Articulates Against the Posterior Part of Articular Eminence Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Centric Relation Does Not Always Coincide with Maximum Intercuspal Position (MIP) Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Centric Jaw Relation Does Not Always Coincide with MIP Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Deflective (Premature) Occlusal Contact of Tooth #1 Shifts Mandible Forward When Moving from Centric Jaw Relation into MIP

Casts Mounted on an Articulator to Reproduce the Relative Position and Movement of the Mandible Relative to the TMJ Anatomy

C. Physiologic Rest Position Vertical dimension of rest (physiologic rest position) Interocclusal rest space or freeway space

Effect of Posture on Physiologic Rest Position (Differs Leaning Back Versus Sitting Up)

D. Jaw Relationships During Horizontal Movements of the Mandible Protrusive Jaw Relation and Occlusion Lateral Mandibular Relation and Occlusion

1. Protrusive Jaw Relation and Occlusion: Anterior Horizontal and Vertical Overlap Provide Incisal Guidance of Mandible (Anterior Protected Occlusion) Separating Posterior Teeth Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Protrusive Jaw Relation and Occlusion: Maximum Protrusion of the Mandible Usually Results in Anterior Crossbite Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

2. Lateral Mandibular Relationship and Occlusion: Canine Overlap Results in Mandible Moving Inferiorly Toward the Working Side (Laterotrusion), thus Separating Posterior Teeth (Disocclusion)

IV. Functional Movements: Chewing and Swallowing Incising Masticating (Chewing) Swallowing (Deglutition)

V. Parafunctional Movements and Heavy Tooth Contacts: Signs and Symptoms Examples of parafunctional (nonfunctional) contacts Clenching Bruxing Biting on pipe stem, pencil, fingernails Cheek biting

Possible Symptoms Related to Parafunctional Contacts Ringing in ears (tinnitus) Sinus pain Dizziness Head, neck, and/or back aches TMJ pain (also from arthritis, injury) Tired muscles of mastication Sore tooth (sensitive to percussion)

Possible Signs Related to Parafunctional Contacts [cont.] Tooth mobility (fremitus) Tooth wear (flat, shiny facets) Widened periodontal ligament Angular bone loss Thickened lamina dura Root resorption

VI. Treatment Methods Related to Malocclusion Teach avoidance: avoid clenching Patient education Biofeedback Jaw muscle exercises Nutritional counseling Tranquilizers and muscle relaxants Psychological counseling Occlusal bite guard or adjustment

Occlusal Devise (Also Called Bite Plane, Night Guard) Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Full Mouth Rehabilitation (an Older Example of Changing All Occlusal Surfaces with Restorations) Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Full Mouth Rehabilitation (a more Contemporary Example of Changing all Occlusal Surfaces with Restorations) Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Surgery to Realign Jaws (in this Case, Shortening the Mandible to Change Class III Relationship to Class I)

VII. Advanced Topics in Occlusion Envelope of Motion Anterior Deprogramming and Accurate Recording of the Centric Relation Jaw Position Long Centric Articulation

Frontal Envelopes of Motion Showing Maximum Movement of the Mandible: Note Movement from MIP where the Mandible Moves Down and Laterally Indicating Canine Overlap Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Total Maximum Movement of Mandible Seen on Sagittal Envelope of Motion: Retruded Opening from MIP at First is Hinge; Opening More Widely is then Translational Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Anterior Deprogramming Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Anterior Deprogramming: Sliding Guiding Inclined Gauges Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

After Anterior Deprogramming: Registration in Centric Jaw Relation Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Learning Exercise: Maximum Protrusion = H + P Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Learning Exercise [cont Learning Exercise [cont.]: Total Lateral Movement (Side to Side) = Maximum Left Lateral Movement + Maximum Right Lateral Movement Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Learning Exercise [cont.]: Maximum Opening = V + All of O Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Learning Exercise: Sketch All Teeth in Ideal Class I Occlusion Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Learning Exercise: Sketch All Teeth in Ideal Class I Occlusion [cont.] Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins