Lecture 9 Flashcards
the first key to normal occlusion is ___
molar relationship
how many “keys to occlusion” did lawrence andrews develop?
6
how did lawrence andrews determine the 6 keys to occlusion?
they were established as meaningful not solely because all of the keys were present in the cases he studied, but also because the lack of even one of the 6 keys was a defect predictive of an incomplete end result in treated orthodontic models
describe the molar relationship of normal occlusion
-the traditional description of a normal class I molar relationship is the MB cusp of the maxillary 1st molar occludes with the buccal groove of the mandibular 1st molar -however, all of andrews’ cases showed the distal surface of the maxillary 1st permanent molar contacting the mesial surface of the mandibular 2nd molar, and the closer the case is to this molar relationship, the better the opportunity for normal occlusion, so the sufficiency of the traditional description of a normal class I molar relationship is questioned
the second key to normal occlusion is ___
crown angulation (or tip)
what is crown angulation with respect to normal occlusion?
the gingival portion of the long axes of crowns is more distal than the incisal portion
the degree of crown angulation/tip is the angle between ___
the long axis of the crown, as viewed from the labial or buccal surface, and a line bearing 90* from the occlusal plane
what does a “plus” or “minus” crown angulation mean?
-a plus reading is awarded when the gingival portion of the long axis of the crown is distal to the incisal portion -a minus reading is assigned when the gingival portion of the long axis of the crown is mesial to the incisal portion
relative to andrews 2nd key to normal occlusion, normal occlusion is dependent upon proper ___, especially for which teeth?
proper distal crown tip, especially for the maxillary anterior teeth since they have the longest crowns
relative to andrews’ 2nd key to normal occlusion, the degree of tip of the ___ determines the amount of ___, and therefore has a considerable effect on posterior occlusion as well as anterior esthetics
the tip of the incisors determines the amount of M-D space they consume
andrews’ 3rd key to normal occlusion is ___
crown inclination (bucco-lingual inclination or torque)
what does a plus and minus reading for crown inclination mean?
-a plus reading is given if the gingival portion of the crown is lingual to the incisal portion -a minus reading is given when the gingival portion of the corwn is labial to the incisal portion
maxillary and mandibular ___ crown inclincations are intricately complementary and significantly affect ___
-anterior -overbite and posterior occlusion
properly inclined anterior crowns contribute to ___
normal overbite and posterior occlusion
the contact points (the position where maxillary occlusal contact should be occurring) move ___ in relation to the mandibular teeth, in concert with the increase in __positive/negative__ maxillary anterior crown inclination
-distally -positive
in all of the cases andrews studied, a negative crown inclination existed in each crown from maxillary ___ through the maxillary ___, with a slightly more negative crown inclination existing in the maxillary ___ and ___
-canine -second premolar -first and second molars
describe how maxillary posterior crown inclination seems counter intuitive to the curve of wilson
the buccal surface of the maxillary posterior teeth have a lingual inclination but also typically have longer lingual functional cusps to contact the mandibular posterior teeth, facilitating the curve of wilson
in all of the cases andrews studied, there was a progressively greater negative crown inclination from mandibular ___ to ___
canines to the second molars
andrews’ fourth key to normal occlusion is ___
elimination of rotations
for “normal occlusion”, why should teeth be free of undesirable rotations?
a rotated tooth occupies more space than a straight tooth, creating a situation unreceptive to normal occlusion
andrews’ fifth key to normal occlusion is ___
tight interproximal contacts
why should patients with genuine tooth-size discrepancies, like peg laterals, have these size discrepancies corrected?
it will allow for proper tight contact points so that the orthodontist will not have to close spaces at the expense of a proper occlusion
andrews’ sixth key to normal occlusion is ___
flat occlusal plane
why are flat-to-slight curves of spee necessary for a “normal occlusion”?
-there is a natural tendency for the curve of spee to deepen with time, because the lower jaw often grows for a longer period of time than the upper jaw -this causes the lower anterior teeth, which are normally confined by the upper anterior teeth and lips, to be forced back and up, resulting in crowded lower anterior teeth and/or a deeper overbite and deeper curve of spee
which angles classification is the most common and what percent of the US population has it?
angles class I, 70%
in a class I occlusal relationship, the ___ of the maxillary first molar articulates with the ___ of the mandibular first molar
-triangular ridge -buccal groove
in a class I occlusal relationship, the maxillary central incisors overlap the mandibular incisors by ___mm
1-2mm
in a class I occlusal relationship, the maxillary canine lies between the mandibular ___ and ___
canine and first premolar
class I occlusal relationships are associated with a ___ facial profile, where the nose, lips, and chin are harmoniously related
orthognathic (straight)
class II occlusal relationships are less common and occur in about ___% of the US population
25%
in a class II occlusal relationship, the ___ of the maxillary first molar falls approximately between the ___ and ___, or the ___ of the mandibular first molar articulates posteriorly to the ___ of the maxillary first molar
-MB cusp -mandibular first molar and the second premolar -buccal groove -MB cusp
class II occlusal relationships are associated with a ___ facial profile
-retrognathic (convex) -the lower jaw and chin may also appear small and withdrawn
in a class II occlusal relationship, the mandibular incisors occlude ___ to the maxillary incisors and typically are in a ___, and may not be in ___
-posterior -deep bite -occlusion
in a class II occlusal relationship, the maxillary canine is ___ to the mandibular canine
mesial
in a class II occlusal relationship, the mandibular incisors are typically tipped in what direction?
bucally
which angles classification is sometimes referred to as a “sunday bite”, and what is it referring to?
-it describes an individual that functions in a class I relationship, but also has a CR/CO shift that allows the patient to function in a class II relationship -a class II patient can fool a professional by biting in a class I position in CO but really they are a class II if they bite in CR
which angles classification is the least common?
-class II (5% of the US population)
in a class III occlusal relationship, the ___ of the maxillary first molar falls approximately between the ___ and ___, or the ___ of the mandibular first molar articulates anteriorly to the ___ of the maxillary first molar
-MB cusp -mandibular first molar and second molar -buccal groove -MB cusp
a class III occlusal relationship is associated with a ___ facial profile
-prognathic (concave) -the chin may also protrude
in a class III occlusal relationship, the mandibular incisors overlap ___ to the maxillary incisors, resulting in a ___
-anteriorly -negative overjet
in a class III occlusal relationship, the maxillary canine is ___ to the mandibular canine
distal
in a class III occlusal relationship, the mandibular incisors will typically be tipped in a ___ direction
lingual
what is pseudo-class III malocclusion?
-the mandibular incisors are forward of the maxillary incisors when in centric occlusion -the patient has the ability to bring the mandible back to centric relation without strain (CR/CO shift) -this type of malocclusion is milder than a true class III and is easier to correct orthodontically
malocclusions in which there is a distal relationship of the mandible to the maxilla make up which angles classification?
class II
what is a class II division I?
class II molar relationship with protruded maxillary incisors
what is a class II division II?
a class II molar relationship where the maxillary lateral incisors are tipped labially and where the central incisors are typically retrudeddd
which class II division patients typically have better growth patterns and require different treatments?
division II
when are class II divisions divided into subdivisions?
when the class II only occurs on one side of the dental arch
what is a class II division II subdivision left?
-describes an occlusion that is a class I molar on the right side and class II on the left side
a patient can be categorized as being class I, II, or III as a dental condition or a skeletal condition. are they always the same classification?
-not always -for example, a patient could have their dental occlusion in a class II relationship, but skeletally they patients maxilla and mandible are normal and would be classified as a skeletal class I -this patient would then be classified as a dental class II and a skeletal class I
typically when a patient has a straight profile, the mandible is proportionally ___ in size to the maxilla, and a dental class ___ molar relationship is formed
-similar -I
typically when the mandible is proportionally smaller than the maxilla, a dental class ___ relationship is formed and a ___ profile is seen
-II -convex
typically when a mandible is relatively greater in size than the maxilla, a dental class ___ relationship is formed and a ___ profile is seen
-III -concave
when describing primary molar relationships, the ___ aspect of the second primary molars is used, and is termed the ___ plane
-distal -terminal
at what point in time do you shift from a primary molar relationship to a permanent molar relationship?
when the second primary molars are lost and during the adolescent growth spurt
the amount of differential mandibular growth and molar shift in the the ___ space determines the permanent molars relationship
leeway
what is leeway space?
-the size differential between the primary posterior teeth and the permanent canine and premolars -usually the sum of the primary tooth widths is greater than that of their permanent successors, so when these primary teeth fall out, there is usually a slight amount of space
the leeway space for the maxillary arch is about ___mm per side, and for the mandibular arch is about ___mm per side
-1.5mm -2.5mm
which terminal plane is the normal relationship in the primary dentition?
flush terminal plane
what is the flush terminal plane relationship?
the distal surfaces of the second primary molars are in an end to end relationship
flush terminal planes will typically shift to a ___ or ___, but this relationship is usually temporary until the second primary molars are lost and the permanent molars then move into a ___ relationship
-class II molar or end-to-end -class I: this tends to happen at age 10 or 11 and is termed the late mesial shift
both the mesial step and the flush terminal plane relationship usually result in the development of a class ___ permanent molar occlusion, but not always
-I -sometimes the flush terminal plane can end up in an end on relationship if the mesial shift doesn’t occur
a mesial step relationship can result in a class ___ or ___ relationship
I or III
in ___ relationships, the permanent molars erupt into a class II relationship or an end on molar relationship
distal step
the primary dentitions normal canine relationship typically has the ___ of the primary maxillary canine articulating with the ___ of the primary mandibular canine
-mesial inclined plane -distal inclined plane
T or F: spacing is normal throughout the anterior part of the primary dentition
true
where is the maxillary primate space located?
between the primary lateral incisors and primary canines
where is the mandibular primate space located?
between the primary canines and the primary first molar
when are primate spaces normally present?
from the time the teeth erupt
___ spaces between the primary incisors are often present from the beginning, but become somewhat larger as the child grows
developmental
generalized spacing of the primary teeth is a requirement for proper ___, which is most frequently caused by growth of the ___
-proper alignment of the permanent incisors -growth of the dental arches
facial lingual position variations can be possible due to differences in growth of the ___
width of the maxilla or the mandible
___ crossbite in the posterior teeth is characterized by contact of the maxillary facial cusps in the opposing mandibular central fossae and the mandibular lingual cusps in the opposing maxillary central fossae
facial crossbite (buccal crossbite)
facial/buccal crossbite results in reversal of ___
the roles of the cusps on the involved teeth, with the mandibular lingual cusps and the maxillary facial cusps becoming supporting cusps and the maxillary lingual cusps and mandibular facial cusps becoming non-supporting cusps
___ crossbite results in a very poor molar relationship that provides little functional contact and is very difficult to correct orthodontically
lingual crossbite (scissor crossbite)
it is important that any restorative work done maintains the proper shape of the occlusal surfaces of teeth to ensure that ___
the functional occlusal contact relationships are restored in harmony with both dynamic and static conditions
maxillary and mandibular teeth should contact uniformly on closing to allow what 3 things?
-optimal function -minimize trauma to the supporting structures -allow for uniform load distribution throughout the dentition
positional stability of well-aligned teeth is crucial if ___ and ___ are to be maintained over time
arch integrity and proper function
T or F: most dentitions deviate from optimal alignment and occlusion
true
many patients adapt well to less than optimal occlusion, but malocclusion may be associated with undesirable changes to what 4 possible things?
-teeth -musculature -TMJ -periodontium and alveolar bone
over time, many concepts of ideal occlusion have been proposed, but in the literature, the concepts of what is ideal, acceptable, and harmful continue to be developed, but class ___ occlusions are the most widely accepted as ideal
I
complex three dimensional mandibular movement can be divided into which two basic components?
translation and rotation
___ is the movement in which all points within a body have identical motion
translation
during translation, the ___ muscle contracts and moves the condyle-articular disc assembly forward
lateral pterygoid
simultaneous, direct anterior movement of both condyles is termed ___
protrusion
simultaneous, direct posterior movement of both condyles is termed ___
retrusion
___ movement is when the body of the mandible is turning about an axis
rotational
rotational movement can happen in what 3 planes?
-sagittal -horizontal -frontal
during rotation around the sagittal plane, rotational movement is limited to about ___mm of incisors separation before the temporomandibular ligaments and structures anterior to the mastoid process force the mandible to translate
12mm
rotation around the ___ plane occurs during lateral movements of the mandible, which rotates around the condyle
horizontal
in a lateral movement in the frontal plane, the nonworking condyle moves ___, whereas the working condyles does what?
-moves down and medially -rotates around the sagittal axis perpendicular to this plane
mandibular movements are limited by what 3 things?
-TMJ -ligaments -neuromuscular system -teeth
how do teeth limit mandibular movements?
the morphology of the tooth is influenced by the pathway it travels across its opposing tooth and the TMJ, ligaments, and neuromuscular system
posselt constructed a 3 dimensional representation of the ___
total envelope of mandibular movement
1, 2, 3, 4, and 5 represent the ___ movement of the incisal edge of the ___ incisors
- protrusive
- mandibular
describe what 1, 2, 3, 4, and 5 specifically represent
- mandibular incisors are guided by the lingual surface of the maxillary incisors
- incisors are in an edge-to-edge position
- represents protrusive movement until the molars contact
- protrusive path along molar contact
- most protrusive mandibular position
what are the extremes of posselt’s diagram during opening and closing?
- far right below #5 is the most protruded opening and closing stroke
- far left below #1 is the retruded opening and closing stroke, representing hinge and translation movements (the pointed area is where the movement changes from hinge to translation)
- green lines represent the maximal lateral mandibular movement (L and R)
- the lowest point represents maximal opening
posterior teeth are well suited for crushing food because of the mutual ___ contacts
cusp-fossa
T or F:
anterior teeth have the same intercuspal position as posterior teeth
- false
- although they show the characteristic maxillary overlap, the anterior teeth have a different relationship in intercuspal position
incisor teeth are best suited for shearing food because of their ___
overlap and the sliding contact ont he lingual surface of the maxillary teeth
which mandibular anterior teeth contact the respective lingual surfaces of their maxillary opponents?
incisors and canines
the amount of horizontal overlap (overjet) and vertical overlap (overbite) can significantly influence ___ and thus influence ___
- mandibular movement
- cusp design of restorations of posterior teeth
how are movements of the mandible controlled anteriorly?
by the horizontal and vertical overlap of the anterior teeth
incisal overlap is characterized in what two dimensions?
- horizontal overlap (overjet) normally 1-2mm
- vertical overlap (overbite) normally 1-2mm
differences in the size of the mandible and maxilla can result in clinically significant variations in ___ relationships; what are two examples?
- incisor
- anterior open bite - negative overbite with positive or negative overjet
- anterior deep bite - overbite greater than 3mm with typically a greater than 3mm overjet
variations in maxilla and mandible size have significant clinical effects on the ___ relationships of the posterior teeth during various jaw movements
contacting
in a ___ bite, the anterior teeth do not provide gliding contact, and there is a lack of anterior guidance
open
in a ___ bite, the anterior teeth occlude apically on the maxillary incisors, which can place a retrusive force on the mandible and the TMJ, and a protrusive force on the maxilla as the patient closes into maximal intercuspation
deep
understanding the function of the anterior teeth and canines and their horizontal and vertical overlap determines ___
the occlusal form of posterior teeth and their restorations
the more horizontal overlap of the anterior teeth (increased overjet), the ___ the posterior cusps should be
shorter
the more vertical overlap of anterior teeth (increased overbite), the ___ the posterior cusps should be
taller
the longer and steeper the angle from 1 to 2, the ___ the posterior cusp height can be
taller
you can have the same horizontal overlap with different vertical overlaps depending on the ___ of the maxillary incisors
angulation
changing the angulation of the incisors will change the angulation of ___
anterior guidance
an increase in vertical overlap produces what 3 things?
- an increased anterior guidance angle
- more vertical component to mandibular movement
- steep posterior cusps
what 3 things will an increase in horizontal overlap lead to?
- a decreased anterior guidance angle
- less vertical component to mandibular movement
- flatter posterior cusps
the use of ___ is the most common method for managing nocturnal bruxism and associated craniomandibular symptoms
- interocclusal orthopedic appliances
- however, there is no consensus on the mechanism of action or best design for optimal clinical results; posterior disocclusion through canine or anterior guidance is believed to be a key feature
what were the results of the study conducted comparing canine guidance and group function in chronic bruxist patients?
- clinical examination and subjective pain ratings did not differ with the two guidance patterns, and the two appliances provided nearly equivalent effects on nocturnal bruxism
- these results question the common assumption that canine guidance is a critical design feature for the management of nocturnal bruxism and associated craniomandibular symptoms
the movements of the mandible are controlled posteriorly by the ___
TMJ and its associated structures
what two bony structures have a great influence on posterior control?
- inclination of the articular eminence
- medial wall of the glenoid fossa
describe how the inclination of the articular eminence influences posterior control of the mandible
- a steeply sloped eminence creates a large downward component of condyllar movement during lateral and protrusive excursion and results in early separation of the posterior teeth
- this would allow for the posterior cusps to be taller
describe how the medial wall of the glenoid fossa influences posterior control of the mandible
- the condylar guidance angle when the mandible moves laterally is greater than when the mandible protrudes straight forward due to the medial wall of the mandibular fossa being generally greater than the articular eminence anterior to the condyle
- variations in the anatomy of the medial wall of each fossa, which nromally allows the condyle to move slightly medially as it travels forward (mandibular side shift, or transtrusion) will also effect cusp height
the more lateral translation the medial wall of the glenoid fossa allows, the ___ the cusp height will have to be
shorter
if a patient has an immediate side shift, the posterior cusp tips will be ___ than if the patient has a progressive longer side shift
shorter
posterior teeth are positioned between the posterior controlling factor (___) and the anterior controlling factor (___) and can be influenced by both to varying degrees
- TMJ
- anterior teeth
in protrusion, the condyle descends along the ___ and is referred to as condylar guidance
articular eminence
___ is the angle at which the condyle moves away from a horizontal reference plane from CR along the articular eminence of the mandibular fossa and is considered to be fixed and unalterable
condylar guidance
in condylar guidance, the steeper the articular eminence, the more the condyle is forced to move ___ as it shifts anteriorly causing a greater ___ movement of the condyle, mandible, and mandibular teeth
- inferiorly
- vertical
anterior guidance is a functional relationship between the ___ and ___
maxillary and mandibular anterior teeth
anterior guidance consists of what 4 components?
- vertical overlap (overbite) of the anterior teeth
- horizontal overlap (overjet) of the anterior teeth
- the steepness of the lingual surface of the maxillary incisors determines the amount of vertical movement of the mandible
- anterior guidance is considered to be a variable that can be altered through orthodontics or dental procedures
teeth that are nearer to the TMJ will parallel more of the ___ movement
joints
teeth that are nearer to the anterior guidance will parallel more of the ___ movement
anterior guidance
with respect to anterior and condylar guidance, when the posterior and anterior controlling factors are the same, they will cause ___
the mandible to move away, paralleling their angulations
for the premolars to be disoccluded during protrusion, the cuspal inclines must be less than ___ degrees if the condylar guidance and atnerior guidance is 45 degrees, and less than ___ degrees if the condylar guidance and anterior guidance is 60 degrees
- 45
- 60
how does the occlusal plane influence mandibular movement?
the more parallel to the condylar guidance, the shorter the cusp height
how does the anteroposterior curve (curve of spee) influence mandibular movement?
the more acute, the shorter the posterior cusp height will have to be before the apex of the curve, and the teeth anterior to the apex of the curve can be taller
the relative positions of ___ and ___ influence mandibular movement
maxillary and mandibular teeth
ideally, the maxillary and mandibular teeth contact simultaneously, and exhibit ___, when the condylar processes are fully seated in the ___, and the teeth do not interfere with ___ during function
- maximum intercuspation
- mandibular fossae
- harmonious movement of the mandible
in many patients, maximum intercuspal contact occurs with the condyles in a slightly translated position, which is referred to as ___ or ___
- maximum intercuspation or centric occlusion
___ is defined as the maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respect articular disks with the complex in the ___ position against the articular eminences
- centric relation
- anterosuperior
T or F:
centric relation is dependent on tooth contact
false
centric relation is clinically discernable when the mandible is directed ___ and ___ and is restricted to a purely ___ movement about the transverse horizontal axis
- superior and anterior
- rotary
because the mandible is a U-shaped bone with joints on both ends, movemen of one joint will produce a ___ in the other joint
reciprocal movement
reciprocal movements of temporomandibular joints:
one condyle may move anteriorly, while the other remains in the ___
anterior movement of only one condyle will produce a reciprocal ___ rotation in the opposite TMJ
- fossa
- lateral
some “play” or looseness can be demonstrated in a normal healthy TMJ, allowing small ___ and ___ movements of the condyles
posterior and lateral
in healthy TMJs, the “play” movements are restricted to slightly less than ___mm laterally, and ___ posteriorly. this looseness can interfere with precise ___ even in healthy joints, making precise positioning of the condyle in the fossa very difficult
- 1mm
- a few tenths of a mm
- TMJ positioning
how can centric relation be determined?
- gently support the mandible so you can feel if the patient is straining to find CR and have the patient place the tip of their tongue on the roof of their mouth as far posterior as possible and allow the musculature to position the patient in CR
- it can also be determined using a deprogrammer
what are the advantages of deprogrammers?
- they require no hand manipulation
- after wearing the deprogrammer, the patient just taps their teeth together in what should be a centric relation position
when morphologic changes occur in the hard and soft tissues of the TMJ due to disease, the ___ relationship is altered
disk-condyle
what 4 ways can the disk-condyle relationship be altered when morphologic changes occur in the hard and soft tissues of the TMJ due to disease?
- deformation
- loosening
- perforation or tearing of the disk
- remodeling of the soft tissue articular surface coverings or their bony support
diseased TMJs have unusual ___, different ___, and altered ___ and ___, which affects dental restorations and should therefore be anticipated and treatment planned for
- disk-condyle relationships
- geometry
- jaw movements and reference positions
what marks the location of the supporting cusps in the maxillary teeth? what about mandibular teeth?
- maxillary - lingual occlusal line
- mandibular - facial occlusal line
supporting cusps contact opposing teeth in their corresponding faciolingual center on a ___ or ___
marginal ridge or fossa
supporting cusp-central fossa contact has been compared to a mortar and pestle because ___
the supporting cusp cuts, crushes, and grinds fibrous food against the ridges, forming the concavity of the fossa
during chewing, the highest forces and longest duration of contact occur at the ___
intercuspal position
___ cusps serve to prevent drifting and passive eruption of the teeth
supporting/holding/functional cusps
what are 4 common characteristic features of supporting cusps?
- they contact the opposing tooth in intercuspal position
- they support the vertical dimension of the face
- they are nearer the faciolingual center of the tooth than non-supporting cusps
- they have broader, more rounded cusp ridges than non-supporting cusps
between supporting and non-supporting cusps, which are more robust and better suited for crushing food?
supporting cusps
during fabrication of restorations, it is important that supporting cusps are not contacting the opposing teeth in a manner which results in ___ of the teeth; rather, the restoration should provide contacts on ___ or ___ so that masticatory forces are directed approximately parallel to the long axes of the teeth
- lateral deflection
- plateaus or smoothly concave fossae
non-supporting or non-functional cusps (non-centric or non-holding) form a ___ line in the mandibular arch, and a ___ line in the maxillary arch
- lingual occlusal line
- facial occlusal line
T or F:
non-supporting cusps overlap the opposing tooth without contacting the tooth
true
when viewed from the occlusal, the nonsupporting cusps are farther from the ___ center of the tooth than supporting cusps
faciolingual
non-supporting cusps have ___ cusp ridges that apparently serve to ___ food as it passes close to the supporting cusp ridges during chewing strokes
- sharper
- shear
the overlap of the supporting and non-supporting cusps helps to ___, preventing ___
keep the soft tissues of the tongue and cheeks out from the occlusal tables, preventing self injury during chewing
what are 3 types of centric cusp contact?
- tooth-to-tooth, cusp to marginal ridge relationship
- tooth-to-two tooth, cusp to two adjacent marginal ridges contact
- tooth-to-tooth cusp-fossa contact
describe the tooth-to-tooth, cusp to marginal ridge relationship type of centric cusp contact
occurs in a class I occlusion, if the maxillary lingual cusps contact only on the distal marginal ridge of a single tooth
describe the tooth-to-two tooth, cusp to two adjacent marginal ridges contact type of centric cusp contact
- the most stable relationship results from the contact of the supporting cusp tips against two marginal ridges
- facilitated by having the marginal ridge heights level with the adjacent teeth which functions well in a tooth-to-two tooth contact
describe the tooth-to-tooth, cusp-fossa contact type of centric cusp contact
- can have a tripod cusp tip to fossa relationship
- when the mandible is sligtly distal to the maxilla, termed a class II tendency, each supporting cusp tip will occlude in a stable relationship with the opposing mesial or distal fossa
- note: other functional holding cusps can exhibit a cusp fossa or tripod relationship depending on the class III or class III relationship
posterior centric/functional cusps are generally developed to contact in the intercuspal position but to disocclude during ___ movements
eccentric mandibular
posterior centric/functional cusps must be tall enough to contact in the intercuspal position but not so tall that they contact during ___ movements
eccentric
what are the 3 typical types of eccentric movements?
- protrusion
- laterotrusion
- mediotrusion
which movement is when the mandible is moved straight forward in relation to the maxilla?
protrusion
which movement refers to the condylar movement that takes place on the working side during lateral excursions?
laterotrusion
which movement refers to the condylar movements that take place on the nonworking side during lateral excursions?
mediotrusion
the 3 eccentric movements create shapes that look like birds feet ___ on the maxillary teeth and ___ on the mandibular teeth
- walking out of the mouth
- down the throat
in a class I occlusal relationship, the lingual cusp of the maxillary first premolar contacts what mandibular centric stop?
the distal marginal ridge of the mandibular first premolar
in a class I occlusal relationship, the lingual cusp of the maxillary second premolar contacts what mandibular centric stop?
distal marginal ridge of the mandibular second premolar
in a class I occlusal relationship, the mesial lingual cusp of the maxillary first molar contacts what mandibular centric stop?
central fossa of the mandibular first molar
in a class I occlusal relationship, the distal lingual cusp of the maxillary first molar contacts what mandibular centric stop?
distal marginal ridge of the mandibular first molar
in a class I occlusal relationship, the mesial lingual cusp of the maxillary second molar contacts what mandibular centric stop?
central fossa of the mandibular second molar
in a class I occlusal relationship, the distal lingual cusp of the maxillary second molar contacts what mandibular centric stop?
distal marginal ridge oft he mandibular second molar
in a class I occlusal relationship, the buccal cusp of the mandibular first premolar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary first premolar
in a class I occlusal relationship, the buccal cusp of the mandibular second premolar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary second premolar
in a class I occlusal relationship, the mesial buccal cusp of the mandibular first molar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary first molar
in a class I occlusal relationship, the distal buccal cusp of the mandibular first molar contacts what maxillary centric stop?
central fossa of the maxillary first molar
in a class I occlusal relationship, the mesial buccal cusp of the mandibular second molar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary second molar
in a class I occlusal relationship, the distal buccal cusp of the mandibular second molar contacts what maxillary centric stop?
central fossa of the maxillary second molar
compared to a class I occlusion, in a class II occlusion, the patient loses the functional fusp occlusion on the ___ and on the ___; the functional contacts shift ___
- distal buccal cusp of the mandibular second molars and on the maxillary first premolars
- posteriorly
in a class II occlusal relationship, the lingual cusp of the maxillary second premolar contacts what mandibular centric stop?
distal marginal ridge of the mandibular first premolar
in a class II occlusal relationship, the mesial cusp of the maxillary first molar contacts what mandibular centric stop?
distal marginal ridge of the mandibular second premolar
in a class II occlusal relationship, the distal cusp of the maxillary first molar contacts what mandibular centric stop?
central fossa of the mandibular first molar
in a class II occlusal relationship, the mesial lingual cusp of the maxillary second molar contacts what mandibular centric stop?
distal marginal ridge of the mandibular first molar
in a class II occlusal relationship, the distal lingual cusp of the maxillary second molar contacts what mandibular centric stop?
central fossa of the mandibular second molar
in a class II occlusal relationship, the buccal cusp of the mandibular first premolar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary second premolar
in a class II occlusal relationship, the buccal cusp of the mandibular second premolar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary first molar
in a class II occlusal relationship, the mesial buccal cusp of the mandibular first molar contacts what maxillary centric stop?
central fossa of the maxillary first molar
in a class II occlusal relationship, the distal buccal cusp of the mandibular first molar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary second molar
in a class II occlusal relationship, the mesial buccal cusp of the mandibular second molar contacts what maxillary centric stop?
central fossa of the maxillary second molar
in a class III occlusion, the patient loses the functional cusp on which teeth? which direction do the functional contacts shift?
- the mandibular first premolars and the central fossa of the maxillary first molars
- the functional contacts shift anteriorly
in a class III occlusal relationship, the lingual cusp of the maxillary first premolar contacts what mandibular centric stop?
the distal marginal ridge of the mandibular second premolar
in a class III occlusal relationship, the lingual cusp of the maxillary second premolar contacts what mandibular centric stop?
central fossa of the mandibular first molar
in a class III occlusal relationship, the mesial lingual cusp of the maxillary first molar contacts what mandibular centric stop?
distal marginal ridge of the mandibular first molar
in a class III occlusal relationship, the distal lingual cusp of the maxillary first molar contacts what mandibular centric stop?
central fossa of the mandibular second molar
in a class III occlusal relationship, the mesial lingual cusp of the maxillary second molar contacts what mandibular centric stop?
distal marginal ridge of the mandibular second molar
in a class III occlusal relationship, the buccal cusp of the mandibular second premolar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary first premolar
in a class III occlusal relationship, the mesial buccal cusp of the mandibular first molar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary second premolar
in a class III occlusal relationship, the distal buccal cusp of the mandibular first molar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary first molar
in a class III occlusal relationship, the mesial buccal cusp of the mandibular second molar contacts what maxillary centric stop?
central fossa of the maxillary first molar
in a class III occlusal relationship, the distal buccal cusp of the mandibular second molar contacts what maxillary centric stop?
mesial marginal ridge of the maxillary second molar
when determining functional occlusal contacts, you should begin with the exam, and ask the patient about what 5 things?
- grinding
- clenching
- sore masticatory muscles
- sensitive teeth
- any other difficulties the patient may be experiencing
when determining functional occlusal contacts, after the verbal exam, what 6 things should you examine the patient for?
- limited mandibular movements
- problems with clenching or grinding
- occlusal fracturing and cracked teeth
- hyper-mobility
- bone loss, recession
- muscle and joint tenderness
what are the 3 steps involved in equilibration of functional occlusal contacts?
- correction of centric contacts and functional cusps
- adjustment of mediotrusive and laterotrusive contacts
- improvement of anterior guidance and canine guidance
when correcting centric contacts and funcitonal cusps, what is the general rule?
grind only on inclined planes and preserve the tips of the “holding cusps” and canine tip and incisal edges
what are 3 points to remember when adjusting mediotrusive and laterotrusive contacts?
- if the patient has canine guidance occlusion, there should be few corrections needed because the canines cause posterior disocclusion
- mediotrusive contacts need to be adjusted first because they cannot only interfere with laterotrusion, but they’re considered destructive
- after the mediotrusive interferences are removed, further laterotrusive and mediotrusive contacts need to be adjusted together because, as laterotrusive contact is adjusted, it can create some mediotrusive contacts on the opposite side
functional occlusal contacts:
when adjusting the laterotrusive side, what is the “bull” rule?
- the adjusting should be done on the buccal of the uppers and the lingual of the lowers preserving the functional cusps as much as possible
- if your patient is in canine guidance, in laterotrusion, the canine should be the only laterotrusive mark in the occlusion
- if your patient is in group function you will see laterotrusive marks from the funtional cusps, from the canine to the second molar
mediotrusive adjustments could compromise functional cusps due to ___. where should mediotrusive contacts be adjusted?
- mediotrusive marks being made on opposing functional cusp inclines
- adjusting the buccal inclines of the upper lingual cusps could remove some of that cusp tip
- adjusting the lingual incline of the lower buccal cusp could do the same thing to that cusp tip
- of the two choices, you should adjust the uppers to keep the lower buccal cusps
- maxillary molars are typically more centrally located over the ridges, keeping occlusal forces directed down the long axis of the tooth with the palatal root helping to distribute the forces
when adjusting for functional occlusal contact, how can improvement of anterior guidance and canine guidance be accomplished?
- most of the anterior adjusting should be done on the lingual of the uppers
- this will even the protrusive movements without changing the centric contacts which should be present on the incisors and canines
- if however, there are long heavy contacts occurring on the labial surface of the lower incisors, those facets should be adjusted by removing all but their incisal edge
- you should continue to adjust until you have protrusive guidance marks for the incisors and also the canines
- there may be protrusive interferences on the posterior teeth and these should be removed if present
after occlusal adjustments, what should you see when checking canine guidance?
- lines in the anterior, which represent protusive and canine guidance movements
- dots in the posterior, which represent functional cusps
sometimes, patients need to be set up in group function. what are 3 reasons?
wear, clenching, or grinding
after occlusal adjustments, what are the similarities and differences between canine guidance and group function?
- they will be similar except for the laterotrusive movements, which are represented on the canines, premolars, and molars in a patient with group function
