Dental Anatomy Lecture 9

What is the TMJ formed by?

The temporal bone and the mandibular condyle

What is the maxilla?

Upper fixed bone of the jaw

It holds the maxillary teeth and forms part of the roof of the mouth

What is the mandible?

The lower movable bone of the jaw

Holds the lower teeth

What is articulation?

The static and dynamic relationship between bones or the occlusal surfaces of the teeth

What is articulation?

The static and dynamic contact relationship between the occlusal surfaces of the teeth during function

What is the glenoid fossa?

The concavity in the posterior-inferior aspect of the zygomatic process of the temporal bone that receives the mandibular condyle

What type of cartilage is at the TMJ

Fibrocartilage

What type of joint is the TMJ?

A compound joint

Made up of 2 bones, a compound joint is usually made of at least 3

What part of the TMJ is a non ossified bone?

The articular disc

Permits complex movement of the joint

What is the craniomandibular articulation considered since the articular disc functions as a third bone?

A compound joint

On which side is the articular surface of the condyle greater?

The posterior aspect

What muscles open the jaw/depress the mandible?

Geniohyoid

Mylohyoid

Digastric

What are the muscles of mastication/jaw elevation muscles?

Temporalis

Masseter

Medial pterygoid

Lateral pterygoid

What do the muscles of mastication do?

Work together to elevate, retract, and move the mandible side to side, facilitation biting and grinding food

What is the function of the anterior and middle bellies of the temporalis muscle?

Elevate the mandible

What does the posterior belly of temporalis muscle do?

Retracts the mandible, but this is controversial

What do the superficial and deep masseter muscles do?

Elevates the mandible

What does the medial pterygoid muscle do?

Elevates the mandible

What does the inferior lateral pterygoid muscle do?

Protrude the mandible

What does the superior lateral pterygoid muscle do?

Stabilize the temporomandibular disc during closing and biting

What does the temporalis do upon contraction?

Moves the mandible superiorly

TMJ also moves superiorly

What does the masseter do upon contraction?

Moves the mandible superiorly and anteriorly

Along with the condyle in the fossa

What is centric relation?

A maxilomandibular relationship independent of tooth contact in which the condyle articulate in the anterior-superior position, with the disc in place against the posterior slopes of the articular eminences

A muscle jaw position

What is maximal intercuspal position/maximum intercuspation?

MIP or MIC

The complete intercuspation of the opposing teeth independent of condylar position, sometimes referred to as the best fit of the teeth regardless of the condylar position

A tooth jaw position

Which arch is larger?

Maxillary

Which anterior teeth are wider?

Maxillary

Creates a greater arch width

Which anterior teeth have a greater facial angulation? What does this cause?

Maxillary

Causes some horizontal and vertical overlapping

How is the root attached to the alveolar bone?

By fibers of connective tissue that span from the roots cementum surface to the bone

They run obliquely from the cementum in a cervical direction to the bone

What are the fibers at the root and alveolar bone known as?

Periodontal ligament (PDL)

What does the PDL do?

Attaches the tooth firmly to its bony socket and helps dissipate the forces applied to the bone during functional contact of the teeth

What are the longest permanent teeth and where are they located?

Canines

Corners of the arches

What is fremitus?

A palpable vibration produced by contact of the fascial incisal of the mandibular anterior teeth with the linguals of the maxillary anterior teeth

Is there fremitus in the maxillary anteriors?

No

What does non axial loading produce?

Horizontal forces which are not tolerated well by teeth, bone, and restorations

What are centric cusps?

Cusps which occlude with the opposing fossa or marginal ridges

What is a class I overjet?

1.5-2.5mm

What is a class I overbite?

2-4mm

In ideal class I occlusion, where are the mandibular posterior and canine teeth relative to the maxillary?

Mesial

What is a face bow?

Used in prosth

Transfers functional and aesthetic components from patient’s mouth to the dental articulator

Transfers relationship of max arch and temporomandibular joints to the cast

Records upper models relationship to the external acoustic meatus and aids in mounting max cast on articular

Records the spatial relationship of max arch to anatomic reference points to transfer onto articulator

Orients the dental cast in the same opening axis of the articulator, customarily the anatomic references are the mandibular transverse horizontal axis through the 2 TMJs and one other selected anterior reference point

What are the parts of the face bow?

Facebow fork

Mounting jig

Earbow

What is the purpose of the facebow?

To transfer both esthetic and functional components from the pt to articulator