Pre-Clinical Occlusion Exam 1

List the six ligaments associated with the TMJ.

1. collateral (discal- medial and lateral)

2. inferior retrodiscal ligament

3. capsular/anterior capsular

4. temporomandibular (IHP and OOP)

5. sphenomandibular

6. stylomandibular

What is the function of the TMJ ligaments as a whole?

restrict mandibular movement

The __ of the mandible articulates with the __ of the temporal bone, separated by a(n) __.

condyle, Glenoid fossa, articular disc

The articular disc of the TMJ is composed of __.

fibrocartilage

The highly sensitive portion of the TMJ due to innervation is the __.

retrodiscal tissue

The condylar heads don't line up horizontally, but rather function together through their __ poles.

medial

A line drawn through the condyles of the mandible converge at the __ and form a(n) __ degree angle.

foramen magnum, 150

What is the function of the periodontal ligament?

acts as a sling and provides feedback to jaw position (proprioception) due to highly innervated fibers

What are the three ways reflex actions and jaw muscle motor neurons are activated?

1. motor cortex that initiates and stops mastication

2. a central pattern generator that provide basic rhythmic activity to jaw muscles (learned)

3. a peripheral input that provides a continuous feedback mechanism (from lots of receptors from mouth)

List the six muscles of mastication.

1. temporalis

2. masseter

3. medial pterygoid

4. lateral pterygoid (superior and inferior)

5. hyoid muscles

6. Auxillary Oral muscles

Where does the temporals originate and insert?

o: temporal fossa of temporal bone

I: coronoid process of mandible

What are the functions of the temporalis?

1. elevates the jaw (anterior portion)

2. retracts the jaw (posterior portion)

Where does the masseter originate and insert?

o: zygomatic arch

I: coronoid process, ramus and angle of mandible

What is the primary function of the masseter?

elevates jaw (can retract)

Where does the medial pterygoid originate and insert?

o: medial surface of lateral pterygoid plate of sphenoid

I: medial surface of angle of mandible

What is the primary function of the medial pterygoid?

elevates jaw (can protrude)

What muscles form the mandibular sling?

1. masseter

2. medial pterygoid

Where does the inferior lateral pterygoid originate and insert?

o: lateral surface of lateral pterygoid plate

I: neck of condyle

What are the functions of the inferior lateral pterygoid muscle?

1. protrusion

2. lateral excursions

Where does the superior lateral pterygoid muscle originate and insert?

o: infra temporal surface of greater sphenoid wing

I: articular capsule, disc and neck of condyle

What is the function of the superior lateral pterygoid muscle?

protractor of disc in conjunction with elevator muscles

The TMJ is located just anterior to the __.

external acoustic meatus

List the 4 suprahyoid muscles.

1. geniohyoid

2. mylohyoid

3. digastric

4. stylohyoid

What are the functions of the suprahyoid muscles?

1. elevate the hyoid

2. depress the mandible

List the three infrahyoid muscles.

1. thyrohyoid

2. sternothyroid

3. omohyoid

What is the function of the infrahyoid muscles?

lower hyoid allowing suprahyoids to depress mandible

What are the functions of the hyoid bone?

helps in...

1. depressing mandible

2. moving the tongue

3. swallowing

What muscles open the mandible?

1. infrahyoids

2. suprahyoids

3. lateral pterygoid

What muscles close the mandible?

1. temporalis

2. masseter

3. medial pterygoid

What are the auxiliary oral muscles?

1. buccinator

2. orbicularis oris

3. tongue

4. posterior neck muscles (sternocleidomastoid, trapezius, intrinsic neck muscles)

What are the functions of the buccinator?

1. cheek support

2. bolus movement

What is the function of the orbicular oris?

lip closure and bolus movement

What is the function of the tongue?

bolus movement and initiate deglutition

What is the function of the posterior neck muscles?

head positioning

The __ system is the functional unit of the body primarily responsible for __, __ and __.

stomatognathic (masticatory), speaking, chewing, swallowing

What two things keep the articular surfaces of the TMJ in constant contact?

1. interarticular pressure (muscles as they pull across the TMJ)

2. the morphology of the articular disc is self positioning

True or False: The articular surfaces of the TMJ must maintain constant contact.

true

Anatomically, the TMJ is a __, characterized by the __.

compound joint, presence of at least three bones

Functionally, what type of joint is the TMJ?

ginglymoarthrodial joint

What does ginglymoarthroidal joint mean?

ginglymoid - hinges in one plane

arthrodial - gliding motion

What types of movement occurs in the TMJ and where do they take place?

rotational - inferior joint cavity

translational - superior joint cavity

Rotation of the mandible occurs around the __.

horizontal condylar axis

How does the posterior border of the mandible move during rotation?

moves backwards

What happens to OOP of the temporomandibular ligament during pure rotational movement?

is loose but starts to tighten

When does translational movement begin with respect to the OOP of the temporomandibular ligament?

when it becomes tight

How far can the mouth open with rotational movement?

20-25 mm

How far can the mouth open with both rotational and translational movement?

40-45 mm

What is the shape of the articular disc?

biconcave, thicker on the outer edges

Where is the inferior joint cavity located?

between the condyle and articular disc

Where is the superior joint cavity located?

between the glenoid fossa and articular disc

What is the function of the super retrodiscal lamina? What helps it accomplish this?

attaches articular disc to glenoid fossa at tympanic plate and "pulls" disc back when the mandible closes

lots of elastic fibers

What is the function of the anterior capsular ligament?

attaches articular disc superiorly to articular surface of temporal bone and inferiorly to anterior articular surface of condyle (also attached to superior lateral pterygoid muscle) to keep disc from losing contact distally from a totally translated condyle

What is the anterior capsular ligament composed of?

collagenous fibers

What is the function of the inferior retrodiscal lamina?

protects retrodiscal tissue by limiting movement of condyle in a posterior direction and protects condyle from entering skull during forceful blow

What is the inferior retrodiscal ligament composed of?

collagenous fibers

What muscle helps stabilize the articular disc during the power stroke and stabilizes the disc v. the superior retrodiscal lamina?

superior lateral pterygoid

What provides nutrients to the dense fibrous connective tissues as well as lubricates them?

synovial fluid

What do the SLP and ILP muscles do during mouth opening?

SLP does not contract

ILP does contract

What is the position of the superior retrodiscal lamina during contraction?

it is tight

What muscle rebounds and opposes the force of the superior retrodiscal lamina during mouth closing?

superior lateral pterygoid

What do the SLP and ILP muscles do during mouth closing?

SLP contracts

ILP relaxes

(opposite of opening)

What is the position of the superior retrodiscal lamina during mouth closing?

relaxes

What nerves innervate the TMJ?

1. auriculotemporal

2. masseteric

3. posterior deep temporal

What two major arteries supply the TMJ?

1. superficial temporal

2. deep maxillary

What branches of the superficial temporal artery supply the TMJ?

1. transverse facial

2. middle temporal

3. zygomatico-orbital

What branches of the deep maxillary artery supply the TMJ?

1. deep auricular

2. anterior tympanic

3. middle meningeal

4. posterior branch of deep temporal

5. masseteric

True or false: The TMJs cannot function independently of each other.

true

True or false: the TMJs rarely function with identical concurrent movements.

true

__ in a dental context means simply the contact between teeth.

occlusion

More technically, occlusion is the relationship between the __ and __ teeth when they approach each other as occurs during chewing or at rest.

maxillary, mandibular

__ refers to contact between teeth when the jaw is closed and stationary.

static occlusion

__ refers to occlusal contacts made when the jaw is moving as with chewing.

dynamic occlusion

__ is the misalignment of teeth and jaws, or more simply a bad bite.

malocclusion

True or false: malocclusion can cause a number of health and dental problems.

true

An articulator is a mechanical instrument that represents the __ and __, to which casts may be attached to simulate all or some of the __.

TMJ, jaws, mandibular movements

What are the advantages to building restorations or prostheses created on an articulator?

1. easier to construct

2. generally more accurate in restoring the patient's occlusal surface

What is the value of using an articulator?

allows variations of a patient's skeletal morphology and maxillo-mandiblar relationships to be recorded and simulated

What does an articulator simulate and why?

mandibular movements for diagnostic and restorative purposes

True or false: variations in posterior and anterior guidance transferred from the patient to the articulator will influence the occlusal anatomy and general tooth morphology.

true

What elements control the occlusal interface?

1. occlusal vertical dimension

2. condylar guidance

3.. anterior guidance

4. correct spacial relationship of members connecting maxillary and mandibular casts

What is the articulator's purpose from a static and functional purpose?

static - relates maxillary and mandibular casts to one another in CO or MIP

functional - reproduces condylar movement, reproducing the path the lower teeth take in relation to the maxillary teeth during functional movements

What are the three practical uses of an articulator?

1. diagnostic

2. treatment planning

3. treatment

In what ways can an articulator be used in treatment planning?

1. selective grinding

2. functional diagnostic wax up

3. esthetic diagnostic wax up

4. orthodontic needs

5. designing restorative procedures

6. patient education

What is Monson's spherical theory?

an articulator can be designed around a sphere with a radius of 4 inches

In what three ways are articulators classified?

1. by where representation of the head of the condyle is located

2. by class

3. by ability to adjust and duplicate mandibular movements

What is an arcon articulator?

ball is attached to the lower member

What is a non-arcon articulator?

ball is attached to upper member of the articulator

A simple holding articulator capable of accepting a single static registration (vertical, non-adjustable articulator) is __.

class I

An articulator that permits a horizontal as well as vertical motion, but does not orient the motion to the TMJ is __.

class II

An articulator that simulates condylar pathways by using average or mechanical equivalents for all or all of the motion is __. These instruments allow for orientation of the casts to the joints and may be arcon or non-arcon instruments (semi-adjustable).

class III

What is Bennet's angle? What is it most often set at?

measure angle of mediotrusive movement of the orbiting condyle

set at 15 degrees

What is the function of the incisal guide table?

preserves anterior guidance

What determines the incisor guidance?

relationship of the anterior teeth

What do the lateral settings of the incised guide table reflect?

canine guidance

True or false: Most class III articulators have a straight line for the condylar guidance, when in reality it is a curved path.

true

An instrument that will accept 3D dynamic registrations; these instruments will allow for the orientation of the casts to the TMJs and simulation of mandibular movements.

class IV

Class IV articulators are __ adjustable.

fully

What device records the shape of the glenoid fossa to the articulator?

pantograph

What are the pros and cons to using a non-adjustable articulator?

pros: less expensive and time up front

cons: more time needed later to adjust restorations in the mouth

What are the pros and cons of using a semi-adjusable articulator?

pros: restorations more closely fit the occlusal scheme of the patient

cons: more time is necessary initially and is more expensive