Dental Anatomy: Proximal Contact Areas & Embrasures

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Questions and Answers

Which muscle is primarily responsible for the lateral excursion of the mandible?

Left lateral pterygoid muscle (correct)

Masseter muscle

Right lateral pterygoid muscle

Temporalis muscle

Which ligaments control movement on the medial side of the temporomandibular joint?

Stylomandibular ligament and sphenomandibular ligament (correct)

TMJ ligament and stylomandibular ligament

Sphenomandibular ligament and temporomandibular ligament

Lingual and labial frena

What is the role of the articular disk in the temporomandibular joint?

It serves as a site for muscle attachment.

It provides structural rigidity to the joint.

It increases the range of motion of the mandible.

It prevents bone-on-bone contact during movement. (correct)

What movement occurs first as the teeth begin to separate?

Rotational movement Signup and view all the answers

What function does the temporomandibular ligament serve?

Prevents condyle displacement Signup and view all the answers

What is the concave and convex structure of the articular disk designed to accommodate?

The contours of the mandibular fossa Signup and view all the answers

How is the synovial fluid in the TMJ maintained?

It is secreted by the lining epithelium of synovial cavities. Signup and view all the answers

What happens during the gliding movement of the mandible?

The condyle moves anterior to the crest of the articular eminence. Signup and view all the answers

What is the primary function of proximal contact areas between teeth?

To prevent food from packing between teeth Signup and view all the answers

What occurs as a result of a cervical embrasure?

Loss of gingival tissue between teeth Signup and view all the answers

Which area is crucial for the self-cleaning action of teeth?

Embrasure spaces Signup and view all the answers

Where is the buccal height of contour usually located on anterior teeth?

At the cervical third of the tooth Signup and view all the answers

What primarily influences the curvature of the cementoenamel junction (CEJ)?

The height of the contact area above the crown cervix Signup and view all the answers

What is one of the purposes of embrasures in dental anatomy?

To protect the gingiva from excessive trauma Signup and view all the answers

How does the location of the lingual crest of curvature differ between anterior and posterior teeth?

It is at the cervical third for anterior and the middle third for posterior teeth Signup and view all the answers

What does the term 'contact point' specifically refer to in dental terminology?

The area where two teeth touch at their occlusal surfaces Signup and view all the answers

What is the primary characteristic of the curvature of the cementoenamel junction (CEJ) on the distal surface of a tooth?

It is approximately 1 mm less than the mesial surface curvature. Signup and view all the answers

Which of the following statements accurately describes the functions of the genioglossus muscle?

It aids in the protrusion, retrusion, or depression of the tongue. Signup and view all the answers

Which statement best describes the mesioincisal angles of maxillary lateral incisors compared to distoincisal angles?

Mesioincisal angles are more square than distoincisal angles. Signup and view all the answers

What condition describes the wide open contact between two adjacent teeth that allows food to pass freely?

Diastema. Signup and view all the answers

How do the distal incisal edges of anterior teeth typically compare to mesial incisal edges?

They are more rounded. Signup and view all the answers

What is a unique feature of the maxillary first molars in terms of their occlusal view?

They exhibit a prominent cusp of Carabelli. Signup and view all the answers

In terms of their curvature, how do the mandibular anterior teeth compare to maxillary anterior teeth?

They have less curvature. Signup and view all the answers

Which structures are found at the bottom of the troughs surrounding the circumvallate papillae on the tongue?

Salivary glands known as the glands of von Ebner. Signup and view all the answers

Study Notes

Proximal Contact Areas

Proximal contact areas, located on the mesial and distal surfaces of teeth, serve as the point of contact between adjacent teeth.
They prevent food from packing between teeth, provide support and anchorage, and resist displacement.
Contact points occur where the occlusal cusp of one tooth touches the occlusal portion of another tooth in the opposing arch.

Cervical Embrasure

A cervical embrasure is a space between teeth formed due to gingival recession, leaving the interdental papilla and bone not fully filling the interproximal space.
Larger cervical embrasures are associated with more missing papilla.
These embrasures can lead to bacterial accumulation, calculus, and food debris, creating potential health concerns.

Embrasures Purpose

Embrasures facilitate food removal from contact areas, dissipating occlusal trauma forces.
They also contribute to self-cleaning by the tongue, cheeks, and lips, protecting the gingiva from excess trauma.

Facial and Lingual Contours

The facial and lingual contours of teeth vary between individuals.
Generally, the buccal height of contour for both anterior and posterior teeth is located at the cervical third of the tooth.
The lingual height of contour for anterior teeth is also in the cervical third, while the lingual crest of curvature for posterior teeth is positioned at or near the middle third.
The crest of curvature represents the widest part of the tooth crown, coinciding with the height of contour.

Curvature of Cementoenamel Junction

The curvature of the cementoenamel junction (CEJ) is determined by the height of the contact area above the crown cervix and the labiolingual or buccolingual diameter of the crown.

Movements of the Jaw and Larynx

Mandibular protrusion is facilitated by the lateral pterygoid muscles.
Mandibular retrusion is achieved by the posterior or horizontal fibers of the temporal muscle and the digastric muscle.
Lateral excursion of the mandible involves the contraction of a single lateral pterygoid muscle, with the left lateral pterygoid muscle contraction moving the mandible to the right.

Structure of the Temporomandibular Joint – Articulation

The temporomandibular joint (TMJ) forms the articulation between the temporal bone and the mandible, where one surface moves over the other.
It functions as a bilateral joint, with the mandible fused at the midline.
The articular disk, a fibrous pad, resides between the TMJ bones.
It possesses a concave and convex upper surface, matching the contours of the mandibular fossa (glenoid fossa).
The disk is thickest at its posterior end (posterior band) and thinnest in the middle (intermediate zone).

Structure of the Temporomandibular Joint – Synovial Cavities

Two synovial cavities are situated above and below the articular disk, lined by epithelium that secretes synovial fluid.
Synovial fluid allows the surfaces to rub without irritation.

Structure of the Temporomandibular Joint – Fibrous Capsule

The TMJ is enclosed by a fibrous capsule.
The temporomandibular ligament strengthens its lateral aspect, preventing condyle displacement.
The stylomandibular and sphenomandibular ligaments control medial movement.

Rotational Movement

As teeth separate, an initial rotational movement occurs in the lower synovial cavity between the disk and the condyle.
The posterior elastic lamina pulls posteriorly on the disk, causing the disk and condyle to rotate against each other.
This rotational movement persists as the jaw opens further.
Additional anterior gliding movement occurs along the posterior slope of the articular eminence.

Gliding Movement

Gliding movement takes place between the disk and the temporal bone.
The condyle and disk move forward until slightly anterior to the crest of the articular eminence.

General Rules of Tooth Identification

The distal surface of a tooth has a CEJ curvature approximately 1 mm less than the mesial surface.
Tooth roots typically curve distally, especially at the apex.
The distal incisal edges of anterior teeth are more rounded compared to their mesial counterparts.

Maxillary Lateral Incisors – Right vs. Left

Exhibit mesioincisal angles that are more square than distoincisal angles.
The cervical line crest is often displaced distally from the labial or lingual view.
The mesiocervical line curves more incisally than the distocervical line.

Maxillary First Molars

The occlusal view displays a prominent oblique ridge, less likely to be crossed by a groove.
Possess three roots.
Typically exhibit five cusps.
May feature a Cusp of Carabelli on the mesiolingual cusp.
The mesiolingual cusp is larger than the distolingual cusp on the right and left sides.

Papillae – Circumvallate or Vallate

Form a V-shaped row composed of circular, raised structures.
Approximately 13 elevations are present.
Located about two-thirds of the way back on the tongue, with the point of the V facing posteriorly.
These papillae develop from different pharyngeal arches.
They rest in troughs surrounded by taste buds along their lateral surfaces.
Salivary glands known as the glands of von Ebner are located at the bottom of the trough.

Tongue Muscles – Extrinsic Muscles

Palatoglossus: Runs from the anterior soft palate, extending downward and forward towards the tongue's lateral borders. Elevates the tongue's posterior part and pulls it slightly backward.
Genioglossus: Originates from the superior genial tubercles and inserts into the tongue's midline, extending from tip to base. Aids in tongue protrusion, retrusion, and depression.

Open Contact and Diastema

An open contact exists when adjacent teeth don't touch tightly at their contact areas.
This open space traps food debris.
A wide open contact is called a diastema.
Large diastemas might be large enough to prevent food trapping and allow for self-cleaning.

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Description

This quiz covers essential concepts related to proximal contact areas and cervical embrasures in dental anatomy. Understand their roles in dental health, food distribution, and the implications of gingival recession. Test your knowledge on how these features interact to maintain oral hygiene.