Occlusion , Test 2 Flashcards
occlusion
static relationship of teeth and is basic to all dentistry
name some constant forces that are important in occlusion
lips/cheeks, tongue, opposing teeth.
what is the neutral position or space?
when tooth stability is achieved. This occurs when lingual forces are in equilibrium of labial/ cheek forces
what are parafunctional habits?
any habitual use of the mouth unrelated to eating, drinking, or speaking
which teeth are easiest to move?
anterior- because their small root
name some parafunctional habits
fingerbiting, bruxism ( clenching vs grinding), mouth breathing, tongue thrust, thumb sucking
proximal surfaces & mesial drifting
Proximal contact between adjacent teeth help maintain the teeth in normal alignment. Alveolar bone and gingival fibers functional response results in mesial drifting which helps sabalize adjacent teeth and the dental arch
occlusal stability helps what?
prevents extrusion or supererutption of teeth.
what happens if a portion of the occlusal surface of a tooth is lost or altered?
shifting of the tooth , supereropt of unopposed teeth until occlusal contact is reestablished
itra-arch alignment
relationships of teeth within the same arch
inter-arch alignment
relationship of teeth between arches ( occlusion)
describe a posterior crossbite
mandibular lingual cusps occlude in the central fossae of maxillary teeth, Maxillary buccal cusps occlude in the central fossae of mandibular teeth. ** mandibular teeth are on the outside**
how is arch length measured?
line begins at distal surface of 3 molar and extends to distal 3 molar on other side
what makes the mandibular arch length smaller?
the smaller mandibular incisors
what is arch width
distance straight across the arch.
what’s another name for functional cusps?
centric/ supporting
name the centric cusps
buccal cusps of mandibular posterior teeth, lingual cusps of maxillary posterior teeth
where do the centric cusps occlude?
the opposing central fossa areas
what do central cusps do?
responsible for maintain the distance between the maxilla and mandible
what is VDO?
Vertical dimension of occlusion- distance between maxilla and mandible which supports the vertical facial height.
what do centric cusps look like?
broad and rounded
centric cusp location from occlusal view is where
1/3 the distance of the buccal lingual width
name the non-centric ( guiding ) cusps
buccal cusp of maxillary posterior teeth, lingual cusps of mandibular posterior teeth.
non-centric cusps appearance
sharp, located 1/6 the of the total buccal lingual distance
whats the pneumonic for non-centric cusps?
BULL, Buccal upper, lingual lower.
what is the functional outer aspect?
FOA, a small area of the centric cusp in the outer aspect wich can function against the inner incline of the noncentric cusp. This helps with shearing food so non-centric cusps are also referred to as shearing cusps
noncentric cusps role in masticating
they finish the guiding contacts that provide feedback to the neuromuscular system which controls the chewing stroke, Non-centric cusps are referred to as guiding cusps
occlusal relationships of 1st molar
mandibular molar is slightly mesial to maxillary
angle classification 1
MB cusp of mandibular 1st molar occludes with embrasure area between 1st molar and 2nd PM, MB cusp of maxillary 1st molar is over buccal groove of mandibular 1st Molar, ML cusp of 1st maxillary molar is in the central fossa of mandibular 1st molar
whats another name for class 1?
orthognathic profile, or normal profile
angle classification 2 (malocclusion)
maxillary arch is larger or advanced anteriorly, or mandibular arch is small or positioned posteriorly
name some determining factors of class 2
MB of mandibular first molar occludes in CF of maxillary first molar, MB cusp of mandibular first molar is aligned in buccal groove of maxillary first molar, DL cusp of maxillary first molar occludes in the CF of mandibular first molar.
whats another name for class 2
retrognathic profile
class 3 angle ( malocclusion)
(predominate growth of mandible) DB cusp of mandibular first molar is in embrasure between maxillary second PM and first Molar, MB cusp of maxillary first molar is situated over the embrasure between mandibular first and second molar, ML cusp of maxillary first molar is situated in the mesial pit of the mandibular second molar
another name for class 3
prognathic
relationships of anterior teeth
maxillary teeth are labial to mandibular, anterior teeth are inclined, mandibular incisal edges contact maxillary lingual sides of teeth.
overjet
horizontal distance in which the maxillary anteriors overlap the mandibular anteriors
overbite
vertical plane, distance between the incisal edges of opposing anterior teeth( normally about 3-5mm of overlap)
what 2 things determine anterior guidance?
overjet, overbite
reminder of functions of anterior teeth
cut or incise food , speech , lip support, esthetics.
whats class 2 division 1?
class 2 molar with normal labial inclination of maxillary central and lateral incisors
whats class 2 division 2
class 2 with lingually inclined anterior teeth
class 3 end to end
mandibular teeth reach the gums of maxillary teeth
anterior openbite
no overlap no contact or MICP ( maximal intercuspal contact)
what are the 3 basic mandibular movements
protrusive, laterotrusive, retrusive
what is protrusive contact?
any area of a tooth that contacts an opposing tooth during protrusive movement
posterior protrusive contacts can occur between what?
distal inclines of maxillary teeth and mesial inclines of mandibular teeth.
where is there contact between teeth during laterotrusive movement
inner inclines of maxillary buccal cusps, outer inclines of mandibular cusps; outer inclines of maxillary lingual and inner inclines of mandibular lingual cusps
where is there contact between teeth during messiotrusive movement
inner inclines of maxillary lingual cusp, inner incline of mandibular buccal
what is the working side
working side-the side the mandible is shifting to
nonworking side
most function occurs on the left side, therefore the right side has been designated the non working side
posterior retrusive contacts
mesial inclines of maxillary teeth and distal inclines of mandibular teeth
what is translation?
when all points within a body have identical motion
what is rotation
when the body is turning about an axis
when does rotation happen?
mouth opens and closes around a fixed point or axis within the condyles
when does translation happen
protrusion- the teeth, condyles, and rami all move forward in the same direction
sagittal plane movement
rotational and translational
Rotation occurs around the terminal hinge
rotation of incisor separation
limited to about 12mm before the TMJ ligaments and other structures force the mandible to translate.
mandible movement in a horizontal plane
rotation and slight translation.
mandible movement of frontal plane
non-working condyle moves down and medially, working condyle rotates around the sagittal axis perpendicular to frontal plane
what limits mandibular movement?
ligaments and articular surfaces of TMJ, as well as teeth alignment
what are Border movements ?
when mandible moves through the out range of motion it produces these movements ( looks like a shield to me)
why is the facebow important
they record the anterio-posterior and mediolateral spatial position of the maxillary occlusal surfaces in relation to the transverse opening and closing axis of the patients mandible
why use the articulator
it stimulates jaw movement. Unmounted casts don’t give the technician information about the occlusal relationship
what type of design are whip mix articulators?
ARCON, ( articulator, condyle)
Arcon vs non Arcon
Arcon has condylar housing built in the upper member of articulator simulating real life. Non-Arcon the housing is in the lower member which is opposite to real life.
