Dental Forces and Occlusion Analysis Quiz

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Questions and Answers

What type of forces are stable and run along the long axis of the tooth?

Lateral forces

Tension forces

Axial forces (correct)

Shear forces

Which type of forces can cause damage or injury due to their instability?

Compression forces

Axial forces

Shear forces (correct)

Tension forces

What do tension forces primarily involve?

Stable forces acting vertically

Pushing from opposite sides

Pulling forces acting from opposite sides (correct)

Forces directed at an angle

Which teeth are primarily able to tolerate axial (compressive) loads?

Premolars and molars Signup and view all the answers

What does the line tracings in occlusion analysis indicate?

Point contact transitioning into movement Signup and view all the answers

What characterizes lateral forces in comparison to axial forces?

They are unstable and not along the long axis Signup and view all the answers

Which of the following statements is true about compression forces?

They are stable forces along the long axis Signup and view all the answers

What is true regarding the role of trabecular bone and the periodontal ligament?

They cushion and absorb compressive loads Signup and view all the answers

What type of forces are pulling forces acting from opposite sides in occlusion?

Tension forces Signup and view all the answers

What is the primary risk for anterior teeth when posterior teeth are missing?

Fatigue and fracture Signup and view all the answers

In a Class III lever system, which component is the load?

The food Signup and view all the answers

How does a high occlusal contact affect the lever system in mastication?

Turns a Class III lever into a Class I lever Signup and view all the answers

What happens to the efficiency of the lever system when the load is placed closer to the fulcrum?

Efficiency increases Signup and view all the answers

Which of the following best describes shear forces?

Lateral forces that can cause breakage Signup and view all the answers

What is the role of posterior teeth in relation to anterior teeth?

Protect against shear forces Signup and view all the answers

How does torquing the TMJ complex affect the masticatory system?

Can be detrimental Signup and view all the answers

What is the definition of static occlusion?

The static relationship of the teeth when the jaw is not moving. Signup and view all the answers

Which of the following is NOT a determinant of occlusion?

Jaw Movement Signup and view all the answers

Which term refers to the maximum intercuspation of teeth?

The occlusion when the cusps interdigitate maximally. Signup and view all the answers

How does dynamic occlusion differ from static occlusion?

It studies contacts made during jaw movement. Signup and view all the answers

What best describes centric relation?

The maxillary and mandibular relationships with the jaws in a specific position. Signup and view all the answers

Which characteristic is true of static occlusion?

It emphasizes points of contact between the teeth. Signup and view all the answers

What does vertical dimension refer to in occlusion?

The height of the jaws when closed. Signup and view all the answers

Which statement accurately differentiates centric relation and maximum intercuspation?

Centric relation is a bone-to-bone relationship, while maximum intercuspation involves teeth. Signup and view all the answers

Which muscle is primarily responsible for elevating the mandible?

Masseter Muscle Signup and view all the answers

What is the position of the maxillary canine cusp tip relative to the mandibular canine?

Distal to the embrasure space Signup and view all the answers

Which component is primarily used for Angle's classification when the permanent first molars are absent?

Canine position Signup and view all the answers

Which of the following is considered the most important factor in occlusion?

Centric relation Signup and view all the answers

Which muscle causes the protrusion of the mandible?

Lateral Pterygoid Muscle Signup and view all the answers

In Angle’s Class II Division 1, where is the mesiobuccal cusp of the maxillary first molar positioned?

Anterior to the buccal groove of the mandibular first molar Signup and view all the answers

Which classification indicates a negative overjet?

Class III Signup and view all the answers

What does the rest position of the mandible refer to?

Neutral position of the mandible Signup and view all the answers

What is the consequence of the unilateral contraction of the Medial Pterygoid Muscle?

Moves the mandible to the opposite side Signup and view all the answers

What feature is distinctive of Angle's Class II Division 2?

Excess overbite Signup and view all the answers

In Angle's Class I, where is the maxillary canine cusp tip located?

In the embrasure between the mandibular canine and first premolar Signup and view all the answers

The anatomy of which structure is crucial in determining the mandible position?

Temporomandibular joint Signup and view all the answers

Which of the following indicates the relationship of the maxillary first molar in a Class I classification?

Mesiobuccal cusp is placed over the buccal groove of the mandibular first molar Signup and view all the answers

During centric relation, the mandible is in which position relative to the maxilla?

Most anterior superior position Signup and view all the answers

What is the primary feature that distinguishes Class II Division 1 from Class II Division 2?

Excessive overjet versus excess overbite Signup and view all the answers

Which classification would typically require surgical and orthodontic correction?

Class II Division 1 Signup and view all the answers

What defines centric relation (CR) in the context of the condyles?

The condyles in their most superoanterior positions. Signup and view all the answers

Which of the following statements about maximum intercuspation (MI) is correct?

MI is reliant on the presence of occlusal contacts. Signup and view all the answers

In terms of occlusal contacts, what is true about centric relation and maximum intercuspation?

CR and MI involve different occlusal contacts. Signup and view all the answers

What is required to achieve a repeatable centric relation position according to Dawson?

Special manipulation is necessary to guide the mandible. Signup and view all the answers

Why does centric relation (CR) rarely equal maximum intercuspation (MI)?

CR and MI rarely have identical joint positions. Signup and view all the answers

How is the rest position defined in relation to CR and MI?

It is a neutral state separate from both CR and MI. Signup and view all the answers

What is the significance of the term 'interference-free occlusion' regarding centric relation?

It allows for optimal condyle positioning without interference. Signup and view all the answers

What outcome does not occur in centric relation?

Interference during occlusal function. Signup and view all the answers

Signup and view all the answers

Study Notes

Static Occlusion 1: Rest Position and Intermaxillary Relations

Static occlusion focuses on the contacts between teeth when the jaw is still.
These contacts are points, not lines
Occlusion is the static relationship between incising or masticating tooth surfaces.
Key factors influencing tooth position and occlusion include tooth size, arch width, muscle influence (lips, cheeks, tongue), oral habits (pipe, musical instrument), mesial drift, occlusal contact, and periodontal health.
Axial forces are stable and along the long axis of the teeth (important for premolars and molars).
Shear forces are unstable, not along the long axis, and often cause damage or injury, and are common in anterior teeth.

Learning Objectives

Differentiate between axial and shear forces.
Identify different types of levers.
Define centric relation.
Define maximum intercuspation.
Differentiate between centric relation, maximum intercuspation, and rest position.
Define vertical dimension.
Explain the occlusal scheme used in restorative dentistry.
Classify Angle's relation in a clinical setting.

Parts of a Course in Occlusion

Part 1 (Winter): Static Occlusion I: Rest position and intermaxillary relations; Static Occlusion II: Occlusal contacts; Dynamic Occlusion I: Masticatory Cycle & Envelope of Function; Dynamic Occlusion II: Mandibular Movements; Occlusion review
Part 2 (Spring): Occlusal contacts and mandibular movements: clinical considerations; Occlusion review for finals.

Occlusion: Static vs Dynamic

Static occlusion: Study of tooth contacts when the jaw is stationary. Contacts are points.
Dynamic occlusion: Study of tooth contacts when the jaw is moving. Contacts are lines.

Forces in Occlusion

Forces are a power that causes an object to move.
Forces in occlusion include compression, Shear, and Tension.
Compression: Stable forces along the long axis of the tooth. Found in posterior teeth, absorbed by trabecular bone and periodontal ligaments.
Shear: Unstable forces, often causing damage or movement. Occur laterally and in anterior teeth
Tension: Pulling forces acting from opposite sides and directed along the long axis of the tooth.

Types of Levers

Class 1 lever: Fulcrum (pivot point) is between the load and the effort (e.g., skull and jaw)
Class 2 lever: Load is between the fulcrum and the effort (e.g., muscles in jaw)
Class 3 lever: Effort is between the load and the fulcrum (e.g., muscles in jaw and food)

Angle's Classification

Developed by Edward Angle.
Based on the relative position of the maxillary first molar—canine position if first molar isn't present.
Class I: Mesiobuccal cusp of the maxillary first molar is positioned over the buccal groove of the mandibular first molar, and the maxillary canine's cusp tip is in the embrasure between the mandibular canine and premolar
Class II division 1: Maxillary arch is anterior to normal, and the maxillary canine overlaps the mandibular canine, and there is a relatively high horizontal overlap.
Class II division 2: Maxillary arch is anterior to normal, and the maxillary canine does not reach as far as the first premolars, and there is a relatively high vertical overlap.
Class III: Maxillary arch is posterior to normal, and the mandibular canine overlaps the maxillary canine.

Mandibular Static Positions

Centric Relation (CR): Single most important factor in occlusion, the only condylar position in which an interference-free occlusion is possible.
Maximum Intercuspation (MI): Determined by the teeth’s maximum contact.
Rest Position: Comfortable, upright mandible position where muscles are relaxed.

Vertical Dimension

Vertical Dimension of Occlusion (VDO): Vertical measurement between arbitrary points on the face when the teeth are contacting.
Vertical Dimension at Rest (VDR): Vertical measurement between arbitrary points on the face when the jaws are at rest.

Clinical Considerations

Special manipulation is needed to guide the mandible into CR.
Initial contact identification in CR is difficult.
CR and MI don't always coincide. A discrepancy exists in up to 90% of people.

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Description

Test your knowledge on various forces affecting dental occlusion and the stability of teeth. This quiz covers tension and compression forces, the role of trabecular bone, and how occlusal contact impacts mastication. Perfect for dental students and professionals seeking to reinforce their understanding of dental mechanics.