Dentistry Chapter 1: Tooth Form and Occlusion

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Questions and Answers

On the lingual surfaces of posterior teeth, the facial contour is located at which part of the crown?

Cervical third

Middle third (correct)

Occlusal third

Incisal third

What is the primary consequence of over-contouring?

Food impaction during mastication

Insufficient stimulation of tissues by food

Trauma to the attachment apparatus

Chronic inflammatory state of the gingiva (correct)

Proximal contact areas are generally larger in which region?

Molar region (correct)

Canine region

Incisor region

Premolar region

What is the primary function of properly formed and located proximal contacts and associated embrasures?

Protecting underlying supporting tissue during mastication Signup and view all the answers

What is the typical location of proximal contact areas in maxillary and mandibular central incisors?

Incisal third of the approximating surfaces Signup and view all the answers

What is the term for the V-shaped spaces that originate at the proximal contact between adjacent teeth?

Embrasures Signup and view all the answers

Under-contouring can result in what kind of trauma?

Trauma to the attachment apparatus Signup and view all the answers

What is the primary purpose of embrasures?

To offer protection to underlying supporting tissue Signup and view all the answers

Where are proximal contact areas typically located in posterior teeth?

Middle third of the approximating surfaces Signup and view all the answers

What is the consequence of improper contours on oral health?

Leading to chronic inflammatory state of the gingiva Signup and view all the answers

What is the primary consequence of improper contacts between teeth?

Periodontal disease and halitosis Signup and view all the answers

What is the function of the correct relationships of embrasures, cusps to sulci, marginal ridges, and grooves?

To provide for the escape of food from the occlusal surfaces during mastication Signup and view all the answers

What happens when an embrasure is decreased or absent?

Additional stress is created on teeth and the supporting structures during mastication Signup and view all the answers

What is the consequence of embrasures that are too large?

Little protection is provided to the supporting structures as food is forced into the interproximal space Signup and view all the answers

What is one of the problems of improper restoration?

Improper embrasure form Signup and view all the answers

What is the term used to describe the contact of teeth in opposing dental arches when the jaws are closed?

Occlusion Signup and view all the answers

What is the effect of the number and location of occlusal contacts between opposing teeth on muscle force?

It has important effects on the amount and direction of muscle force Signup and view all the answers

What is the term used to describe the blunt, rounded, or pointed projections of the crowns of teeth?

Cusps Signup and view all the answers

What separates the facial cusps from the lingual cusps?

Central groove Signup and view all the answers

What is the term used to describe the process of grinding and crushing food in the mouth?

Mastication Signup and view all the answers

What is the primary function of incisors during mastication?

Shearing or cutting through food Signup and view all the answers

Which of the following classes of teeth serve a dual role in mastication?

Premolars and molars Signup and view all the answers

What is the primary function of contours in relation to supporting tissues?

To protect and stimulate supporting tissues during mastication Signup and view all the answers

What is the primary determinant of muscle function in mastication?

Tooth form and its contour and contact relationships Signup and view all the answers

What is the role of molars in relation to the vertical dimension of the face?

To maintain the vertical dimension of the face Signup and view all the answers

What is the purpose of proximal contacts between teeth?

To stimulate supporting tissues during mastication Signup and view all the answers

What is the primary role of canines in occlusion?

To serve as guides in occlusion Signup and view all the answers

What is the relationship between occlusal surfaces and periodontal disease?

Occlusal surfaces can contribute to periodontal disease if not properly maintained Signup and view all the answers

What is the primary function of embrasures in relation to food?

To deflect food only to the extent that stimulates supporting tissues Signup and view all the answers

What is the primary role of tooth preparation and restoration in relation to tooth function?

To design and restore proper tooth form and function Signup and view all the answers

What is the position of the mandible called when teeth are brought into full interdigitation with the maximal number of teeth contacting?

Maximum intercuspation (MI) Signup and view all the answers

What type of cusps contact opposing teeth along the central fossa occlusal line?

Supporting cusps Signup and view all the answers

What is the purpose of non-supporting cusps?

To keep the soft tissue of the tongue and cheeks out from the occlusal tables Signup and view all the answers

What is the characteristic feature of supporting cusps according to the faciolingual center of the tooth?

They are closer to the faciolingual center of the tooth than non-supporting cusps Signup and view all the answers

What is the function of supporting cusps in mastication?

To prevent drifting and passive eruption of teeth Signup and view all the answers

What is the significance of the overlap of the cusps between posterior teeth?

It prevents self-injury during chewing Signup and view all the answers

What is the characteristic feature of non-supporting cusps compared to supporting cusps?

They have narrower, sharper cusp ridges Signup and view all the answers

What is the purpose of the depressions between the cusps?

To create fossae for occlusal contacts Signup and view all the answers

What is the characteristic feature of the maxillary arch compared to the mandibular arch?

It is larger than the mandibular arch Signup and view all the answers

What is the significance of the horizontal and vertical overlap of anterior teeth?

It can considerably influence mandibular movement and the cusp design of restorations of posterior teeth Signup and view all the answers

Study Notes

Posterior Teeth Contours and Contacts

The facial contour on the lingual surfaces of posterior teeth is typically located at the cervical third of the crown.
Over-contouring can lead to improper contacts, which may cause food impaction and periodontal issues.
Proximal contact areas are generally larger in the posterior region compared to anterior teeth.

Functions and Locations of Proximal Contacts

Properly formed proximal contacts and associated embrasures help maintain teeth alignment, protect periodontal tissues, and aid in effective mastication.
In maxillary central incisors, proximal contact areas are typically located at the incisal third, while in mandibular central incisors, they are usually positioned at the incisal and middle third.

Embrasures and Their Implications

The V-shaped spaces between adjacent teeth at the proximal contact areas are known as embrasures.
Under-contouring can result in trauma from teeth rubbing against one another, leading to abrasion or sensitivity.
The primary purpose of embrasures is to allow for the passage of food and facilitate the self-cleaning of teeth.

Proximal Contacts in Posterior Teeth

In posterior teeth, proximal contact areas are typically located at the junction of the occlusal and middle thirds of the crown.
Improper contours can contribute to oral health problems, such as increased plaque accumulation and potential dental caries.

Consequences of Improper Contacts

Incorrect contacts between teeth can lead to uneven occlusal force distribution, potential tooth mobility, and discomfort.
The relationships between embrasures, cusps to sulci, and marginal ridges help in smooth functional movements during chewing.

Embrasure Conditions

A decreased or absent embrasure can hinder proper food flow and cleaning, leading to an increased risk of tooth decay.
Embrasures that are too large may lead to food packing and difficulty in cleaning interproximal areas.

Restorations and Occlusion

Improper restoration can cause various issues, including altered function and aesthetics, as well as compromised periodontal health.
The term for teeth contact in opposing dental arches during closure is referred to as "maximum intercuspation."

Occlusal Contacts and Muscle Force

The number and location of occlusal contacts significantly influence muscle forces, promoting effective mastication and oral comfort.
The protruding crowns of teeth can be called cusps, which may be blunt, rounded, or pointed.

Masticatory Functions

The grinding and crushing of food in the mouth is termed mastication, facilitated primarily by molars and premolars.
Incisors primarily function to cut food, leading to effective initiation of mastication.

Role of Different Teeth Classes

Molars and premolars serve a dual role in mastication by both grinding food and stabilizing occlusion.
The anatomy of contours in teeth plays a crucial role in supporting oral tissues and facilitating proper function.

Muscle Function Factors

The primary determinant of muscle function in mastication is the relationship between the upper and lower jaws during occlusion.
Molars play a vital role in maintaining the vertical dimension of the face, which is essential for overall facial aesthetics and function.

Proximal Contacts Between Teeth

Proximal contacts between teeth prevent food impaction and assist in stabilizing dental alignment.
Canines play a key role in occlusion by guiding mandibular movements during function.

Occlusion and Periodontal Health

There is a notable relationship between occlusal surfaces and the risk of periodontal disease, with improper contacts potentially exacerbating the condition.

Embrasures and Food Function

Embrasures' primary function in relation to food is to direct it towards the occlusal surfaces, ensuring efficient mastication.

Restoration in Tooth Function

Tooth preparation and restoration are critical for maintaining the functional integrity of teeth, ensuring they can withstand occlusal forces effectively.

Mandibular Position

The position of the mandible during full occlusal contact is known as intercuspation, which is crucial for effective chewing mechanics.

Supporting and Non-Supporting Cusp Functions

Supporting cusps are involved in occlusion with fossa contacts, primarily aiding in the grinding process during mastication.
Non-supporting cusps serve to guide mandibular movements and assist in stabilizing the dental arch’s structure.

Curve Characteristics

The overlap of cusps between posterior teeth aids in achieving a functional occlusion, ensuring effective food breakdown and distribution of forces.
Maxillary arches typically display a wider and more rounded contour compared to the narrower mandibular arches.

Anterior Teeth Overlap Significance

The horizontal and vertical overlap of anterior teeth is significant for optimal anterior guidance and aesthetic success during occlusion.

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Description

This quiz covers the role of tooth form and occlusion in dentistry, including intra- and inter-arch alignment, tooth function, and design of tooth preparation and restoration.