Dental Occlusion Q2

occlusion is the statis relationship between

the incisal or masticating surfaces of the maxillary or mandibular teeth or tooth

occlusion is the act or process of

closure or being closed or shut

articulation is the place of union or junction between

two or more bones of the skeleton

articulation is the static and dynamic contact relationship between

the incisal/occlusal surfaces of the teeth during function

articulator

a mechanical instrument that represents the temporomandibular joints and jaw to which the maxillary and mandibular casts may be attached to simulate some/all mandibular movements

what are the three determinants of occlusion

posterior and anterior determinants and neuromuscular system

posterior determinants

TMJs w their surrounding tissues

anterior determinants

teeth and their guidance- occlusion or articulation

neuromuscular system

include muscle of mastication, nervous system, skeletal tissue, skeletal arrangements around TMJ

harmony

stable occlusal condition

stable occlusal condition

even and simultaneous contact of teeth, directing occlusal forces through long axis of tooth, and damaging horizontal movements are directed to anterior teeth (farthest from fulcrum and force vectors)

articular disc is interposed between the…

squama of the temporal bone and the condyle of the mandible

the TMJs are coupled, what does this mean

no movement can occur in one joint w/o some movement in the other joint

what are the two compartments of the TMJ of which each accomplishes different types of movement

superior and inferior cavity

ginglymoarthrodial

TMJ- a hinge joint with a moveable socket

the rotating/hinging movements the TMJ provides in one plane classifies it as what type of joint

ginglymoid joint

TMJ provides gliding movements which classifies it as what type of joint

arthrodial joint

which compartment does rotation occur of the TMJ

disc on the articular surface in the inferior cavity

what compartment does the free sliding movement (translation) occur of the TMNJ

between the surfaces in the superior cavity

compound joint requires the presence of

at least 3 bones

TMJ is made up of how many bones

2

the articular disc serves as a ________ bone and is considered as a third bone

non-ossified

what are the extracapsular ligaments of the TMJ

external lateral/temporomandibular, sphenomandibular, stylomandibular ligaments

external lateral/temporomandibular ligament funx

prevents from posterior dislocation of the joint

sphenomandibular ligament

primary passive support of mandible + muscles of mastication

stylomandibular ligament

limits opening and protrusion movements of jaw

the articular disc is composed of

dense fibrous connective tissue; no blood vessels or nerve fibers

the sagittal plane of the articular disc can be divided into 3 zones, rank them according to greatest to least thickness

posterior border> anterior border> intermediate zone

from an anterior view, is the articular disc thicker medially or laterally

medially

TMJ has what types of cartilage

fibrocartilage and secondary cartilage

fibrocartilage has what type of collagen

type I and II

secondary cartilage

intra-membranous ossification; forms after bone formation

what actions does the mandible undergo to engage the maxilla for occlusion

hinge and gliding action

transverse horizontal axis (terminal hinge axis)

an imaginary line around which the mandible may rotate within the sagittal plane

what is the average rotation angle/measurement of incisal opening, when does this occur

12 degrees/20-25 mm; centric relation

what determines the properties of terminal hinge position, is this reproducible

ligaments and TMJ; yes

what tooth is where the joints are in centric occlusion/point of initial contact

2nd molar

centric relation (CR) definition

restricted to a purey rotary movement (rotation) about the transverse horizontal axis; condyle dependent

centric occlusion (CO) definition

occlusion of opposing teeth when the mandible is in centric relation; may/may not coincide w maximal intercuspal position

maximal intercuspal position (MIP) definition

complete intercuspation of opposing teeth, regardless of condylar position

long centric/freedom in centric

CO to MIP slide w no vertical dimension change and no interferences

interocclusal rest space is when the mandible is at rest position with the teeth separated by ______ mm

2-4

if CO and MIP are vertically different, there is a greater __________ risk

pathological

during CO there is no…

muscle funx- jaw hinges w/o lateral pterygoid

centric stop

opposing cuspal fossae contacts that maintain the occlusal vertical dimension between opposing arches

in occlusion, a particular supporting cusp makes contact w a _________ on the opposing teeth

centric stop

during cusp to marginal ridge contact it is one tooth contacting how many teeth

2 teeth

during cusp to fossa contact it is one tooth contact how many teeth

1

supporting cusp in normal occlusion…

the lingual cusp of the upper posterior teeth and the buccal cusps of the lower posterior teeth

non-supporting cusp in normal occlusion…

buccal cusps of the upper posterior teeth and the lingual cusps of the lower posterior teeth

dipod and tripod cusp tip contact location

lateral to cusp tip

tripod

dipod

dipod and tripod cusp tip lateral forces are balanced to…

zero; net force is vertical in long axis

two-to-two-tooth MI contacts

cusp fossae and cusp marginal ridge relationships

tooth-to-tooth MI contacts

all cusp fossae relationships

advantages to tooth to two tooth MI contacts

vertically directed forces, commonly occuring/easy to restore, efficient protections against super eruption

disadvantages to tooth to two tooth MI contacts

greater interproximal food impactions risk, uneven adjacent MR heights may not allow appropriate design

excursive movements occur when the…

mandible moves away from maximum intercuspation

working-side

the side toward which the mandible moves in a lateral excursion

non-working side (balancing)

the side of the mandible that moves toward the medial during lateral excursion

protrusive movement

mandibular forward movement anterior to centric relation

class I

class II

class III

angle class __ molar relationship

I; maxillary first molar MB tip is aligned w mandibular first molar MB facial groove

angle class __ molar relationship

II; maxillary first molar MB tip is anterior to mandibular first molar MB facial groove

angle class ___ molar relationship

III; maxillary first molar MB tip is posterior w mandibular first molar MB facial groove

what do you need to mount the maxillary cast

facebow/earbow

what do you need to mount the mandibular cast

bite reg

face bow/hinge bow

records the spatial relationship of the max arch to some anatomic reference point(s)

purpose of facebow/earbow

transfer establishes the relationship between the upper teeth and pts head