Occlusion, Jaw Movement and Occlusal Contacts

Maximum intercuspation (MI)

mandible with the teeth are brought into full interdigitation wiht the maximum number of teeth contacting

Where it is the most stable with interlocking the 2 arches considered to be?

maximum intercuspation

What is independent on condylar position (meaning only based on teeth)?

maximum intercuspation

Centric Occlusion (CO)

tooth guided position where it depends on the initial tooth contact when the mandible closes

What dos the CO provide?

reference point in restorative procedures

Functional shift

small shift from CO to MI (grinding motion)

Functional occlusion

all contacts during chewing, swallowing, or normal actions

Normal contacts

made during chewing and swallowing

What is the most comfortable joint position?

centric relation

Centric Relation (CR)

maxillomandibular relationship where the functional heads of the condyles are in the most unrestrained, retruded anatomic position in the glenoid fossae of the temporomandibular joints

What is independent on tooth contacts (meaning only based on joint)?

centric relation

Guided ligament position and where the jaw should be

centric relation

Why can't the patients mandible be forced into CR from the rest position?

because a person's reflex neuromuscular defense would resist the applied force

When guiding to the centric relation, how should the mandible be?

relaxed and gently guided

Tonic stretch reflex of the mandibular elevators

usual reflex cited as the basis for the postural position of the mandible

All the muscles that open and close are said to be?

in a state of minimal contraction only to main posture

The mandible is how man y mm away from MI

2-4

Freeway space/interocclusal rest space/interocclusasl distance

distance that the mandible is from the MI

Canine or Cuspid protected occlusion

occlusal relationship in which the vertical overlap of the maxillary and mandibular canines produces a disclusion of all the posterior teeth when the mandible moves to either side

Group function

multiple tooth contacts between the maxilla and mandible in lateral jaw movements

Working side

side to which mandible has been moved during lateral occlusion. the condyle will stay in its fossa, rotates, and moves laterally (working condyle)

Non-working side

Side that the mandible moves away from during a lateral excursion, non-working condyle

Interfering contact (non-working side)

pathway of the maxillary cusps on the mandibular posterior teeth is towards the DISTOBUCCAL

What arch is considered mobile?

mandibular

The contact of lateral movements takes place on which said the maxillary and mandibular inclines?

- maxillary inclines = distal

- mandibular inclines = mesial

In normal alignment, the ML cusp of the maxillary first molar will meet what?

the central fossa of the mandibular first molar

In normal alignment, the DB cusp of the mandibular first molar will meet what?

central fossa of the maxillary first molar

Centric stops

areas of occlusal contact that are supporting cusp makes with the opposing teeth in centric occlusion

Centric contact relatioships depend on what to things?

1. supporting cusps to marginal ridges

2. supporting cusps to fossa

What of the posterior teeth are normally aligned continuously with each other in each quadrant?

central developmental grooves

Protrusive movement

accomplished when the mandible is moved straight forward until the maxillary and mandibular incisors contact edge-to-edge

In what direction do the condyles of the mandible move in protrusive movement?

downward and forward - moves MI to maximum protruded position

What affects the surface morphology of posterior teeth?

Anterior guidance (vertical and horizontal overlap of anterior teeth)

in ideal occlusion, the axes of crowns and roots of both arches are kept __________. 

parallel

occlusion is dictated by what?

underlying basal bone

which arch tends to be larger?

maxilla arch

since the maxillary arch is larger than the mandibular arch is, what happens?

the teeth will overlap buccal slightly

Angle’s classification of malocclusion only considers what?

the sagital aspect of occlusion

what is a “normal” sagittal relationship of the dental arches called?

class 1

if the position of the mandibular arch is too posterior in relation to the maxillary arch, what occurs?

distocclusion which is also known as Class II malocclusion 

what class of occlusion is this?

class II

if the position of the mandibular arch is too far anterior in relation to the maxillary arch, what happens?

mesiocclusion, also known as class III malocclusion

what class is this picture?

class III

what class of occlusion is shown in this x-ray?

class II (x-ray)

what class of occlusion is shown in this x-ray?

class I (x-ray)

what class of occlusion is shown in this x-ray?

class III (x-ray)

in class II, division 1 malocclusion, what occurs?

maxillary incisors are inclined normally or too far labially

in class II, division 2 malocclusion, what occurs?

two or more maxillary incisors are palatally inclined

in severe class II, division 1 malocclusions, the lower lip is what?

positioned between the mandibular and maxillary incisors

in class II, division 2 malocclusions, the lips are what?

closed

what is the curve of spee?

the curvature which begins at the tip of the canines and follows the buccal cusps of the posterior teeth, when viewed from the facial; continues up the arch through the condyle

what is the curve of wilson?

mediolateral curvature of the occlusal plane of posterior teeth

what is the purpose of the curve of wilson?

complement the paths of the condyles during movements of the mandible

what is the curve of monson (also known as sphere of Monson)?

three-dimensional curvature of the occlusal plane, which is a combination of the curve of spee and curve of wilson

jaw movement dictates what?

cuspal height and depth of fossae

in ideal occlusion, what cusps of maxillary teeth are the functional cusps?

lingual cusps

in ideal occlusion, what cusps of maxillary teeth are the non-functional cusps?

buccal cusps

in ideal occlusion, what cusps of mandibular teeth are the non-functional cusps?

lingual cusps

in ideal occlusion, what cusps of mandibular teeth are the functional cusps?

buccal cusps

the non-functional cusps of maxillary molars and premolars help what?

keep the cheek out of the occlusal table, avoiding soft tissue trauma

mandibular lingual cusps (nonfunctioning cusps) help do what?

• shear food as it passes to the functional cusps for chewing

• keep the tongue away from the occlusal table to avoid trauma

when looking from mesial or distal, the crowns of teeth have uniform curvatures where?

• buccal: cervical thirds

• lingual: middle third

the buccal and lingual contours can deflect what?

food away from the gingival margins during mastication

what are the four embrasures per contact area?

• labial or buccal

• lingual

• incisal or occlusal

• gingival or cervical