su14_-_occlusion_ii_exam_1_20141210195244 Flashcards
What are the 2 schools of articulator design? Describe each.
- the geometric (non-anatomic) school: denied the existence of condylar axes and disregarded the condylar paths as influences on occulsion, instead claiming that the articulation of the teeth guides the mandible during mastication- the condylar (anatomic) school: adjustable condylar guides and average value instruments
Describe the Equilateral Triangle Theory. Who created this theory?
- the size of the mandible is equal to 10cm (4 inches) from condyle to condyle and from each condyle to the incisor point- William G. A. Bonwill (1838-1899)
Describe the Balkwill Angle. Who discovered this?
- is formed between the occlusal plane and Bonwill triangle (~26 degrees)- Francis H. Balkwill (1866)
What did Ferdinand Graf von Spee discover?
in 1890, he discovered “the relationship between the curved arrangements of the occlusal planes of natural teeth and the corresponding curves of the condylar paths”
What is the Curve of Spee?
the molar masticatory surfaces lie on the same arc of a circle; the posterior continuation of which touches the most anterior point of the condyle
Where is the location of the axis of the Curve of Spee?
at the level of the horizontal mid-orbital plane
True or false: The steeper the path of the condyles, the less pronounced the tooth curve would be, because both have the same radius.
FALSE. The steeper the path of the condyles, the MORE pronounced the tooth curve would be, because both have the same radius.
What did Carl Christensen discover (“Christensen’s Phenomenon”)?
the space that occurs between the maxilla and mandible during protrusion
True or false: Christensen was the first to describe an intraoral method fro obtaining a protrusive record to determine the condylar inclination.
true
What did George S. Monson discover?
spherical theory - in 1898, Monson presented for the first time a method for setting denture teeth, using Bonwill’s equilateral triangle conforming to the surface of a sphere
Where is the center of rotation in Monson’s Spherical Theory?
sella turcica
What did George H. Wilson discover?
Curve of Wilson - in the theory that occlusion should be spherical, the curvature of the cusps as projected on the frontal plane expressed in both arches; the curve in the lower arch being concave and the one in the upper arch being convex
What theory did Rupert E. Hall develop?
Conical Theory of Mandibular Movement
What is the anatomic rotation center of the mandible, according to the Conical Theory of Mandibular Movement?
external occipital protuberance
The essence of both anatomic and functional harmony is the “balance” between ______ and ______.
elevator and depressor muscles
Name the 2 types of mandibular movement.
rotational and translational
What does THA stand for? (hint: think mandibular movement)
terminal hinge axis or transverse horizontal axis (axis around which the mandibular condyles rotate)
True or false: In lateral movement, the working side is the side toward which the mandible moves.
true
In what directions does the non-working condyle move in lateral movement?
forward, downward, and medial
What is Bennett’s Movement?
movement of the working condyle within a cone
What is Bennett’s Side Shift?
the axis of the working condyle moves laterally? (like a martial artist who turns body from facing front to facing sideways)
What is Ulf Posselt’s Envelope of Motion?
border movement (maximum movement) of the mandible
True or false: Any point found along the arc of rotation is CR.
true
What are the functions (5) of anterior teeth?
- anterior guidance- perform initial acts of masitcation- speech- lip support- esthetics
What are the 3 factors that dictate anterior guidance?
- position of the incisal edge of the mandibular anterior teeth relative to the lingual surfaces of the maxillary anterior teeth- changes in morphology of the lingual surfaces of maxillary anterior teeth- length of mandibular incisors or canines
What are the 2 types of anterior guidance? What is the third type of guidance (that is not a type of anterior guidance)?
anterior guidance:- incisal guidance- canine guidancegroup function
What are the 3 purposes of a custom anterior guidance table?
- when anterior teeth are prepared, the angulation of the custom guide provides anterior guidance in place of the anterior teeth- when only posterior teeth are to be replaced, the angulation of the guide serves to estimate the buccolingual and mesiodistal cusp angles so as to avoid interferences in both protrusive and non-working excursions- reduce the amount of wear of the stone casts during excursive movements made on the articulator
When trimming casts, what type of edges (straight or curved) does ortho casts have? Prosthetic casts?
- ortho casts: straight edges- prosthetic casts: curved edges
What is the term used for an articulator that has the condyles in the lower part (mandible)?
arcon
What is the term used for an articulator that has the condyles in the upper part (maxilla)?
non-arcon
What is the purpose of a pantograph?
used to pinpoint movement with tracing papers at the ear and on front (2 in front, 2 vertical in back, 2 horizontal in back)
What two angles are measured with a pantograph?
Fischer’s angle and Bennett’s angle
What two lines is Fischer’s angle between?
between the protrusive and nonworking lines in vertical dimension
What two lines is Bennett’s angle between?
between protrusive and non-working lines in horizontal dimension
True or false: Bennett’s angle deals with the working side and Bennett’s shift deals with the non-working side.
FALSE. Bennett’s angle deals with the non-working side and Bennett’s shift deals with the working side.
What does the Ear Bow relate the maxillary cast to?
the terminal hinge axis (mandibular condyles)
True or false: The Ear Bow orients the maxillary cast correctly in space using a third point of reference (occlusal plane).
true
The Ear Bow is aligned parallel to what?
the interpupillary line (reference)
True or false: The Ear Bow permits mounting of the mandibular cast on a semi-adjustable articulator.
FALSE. It permits mounting of a MAXILLARY cast.
What is used to mount a mandibular cast after an Ear Bow is used to mount the maxillary?
using a centric relation (CR) record
What is the definition of centric relation?
the maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective disks with the complex in the anterior-superior position against the shapes of the articular eminences; this position is independent of tooth contact
True or false: Centric relation is dependent upon tooth contact.
FALSE. Centric relation is INDEPENDENT of tooth contact.
What are the 3 ways to record CR?
- bilateral manipulation- chin point guidance- anterior deprogrammer (having a patient bite on something for awhile to have their jaw “forget”)
In a CR Record, are any of the teeth touching?
no
True or false: CR Records are thin, soft, fast setting, dimensionally stable, and easily verifiable.
true
What is the average angle of condylar guidance?
40 degrees
What is the average angle of anterior guidance?
20 degrees
What is the average angle of articular eminence?
30 degrees
What is the only time you can ignore CR records?
when the CO = MI
True or false: Hand articulation is not necessary when there is slide present between CO and MI.
FALSE. You need to hand articulate because the articulator will not account fro the slide
How is an optimal joint relationship achieved?
when the articular discs are properly interposed between the condyles and the articular fossae (CR)
What is the purpose of an orthopedically stable joint position?
when the articular surfaces and tissues of the joints are aligned such that forces applied by the musculature do not create any damage
True or false: The musculoskeletally stable joint position can only be maintained when it is in harmony with a stable occlusal position.
true
What two characteristics of contact between teeth are optimal?
even and simultaneous
Is it optimal for CO to coincide with MI?
yes
What is the difference between even and simultaneous contact?
- even: all teeth have the same load- simultaneous: all teeth contact at the same time
What protects the osseous tissues from pressure forces?
periodontal ligament between the roots and the alveolar bone
Which type of occlusion is preferred (cusp-fossa or cusp-marginal ridge)?
cusp-fossa because it is better at receiving force because it takes it along the center of the long axis
What is the best method of axial loading?
tripodization (tip of the cusp should not contact, just the sides)
Describe a class I lever system. Give an example.
(load v) [fulcrum] (effort v)a dolly moving a box
Describe a class II lever system. Give an example.
[fulcrum] (load v) (effort ^)a wheelbarrow
Describe a class III lever system. Give an example.
(load v) (effort ^) [fulcrum]a fishing rod
What class lever system is represented by the jaw?
class III
True or false: The further the load is from the fulcrum, the harder it is to chew.
true
Describe the 2 parts of mutually protected occlusion.
- in maximal intercuspal position, posterior teeth come into contact and act as stops to minimize horizontal load on anterior teeth- the anterior teeth guide excursive movements of the mandible so that no posterior teeth contacts occur during lateral or protrusive excursions
What are the 2 types of anterior guidance?
incisal and canine guidance
What type of guidance is ideal for lateral excursions?
canine guidance (over group function)
What are the 7 effects of tooth loss?
- supraeruption- tilting- loss of contact- loss of posterior tooth support- loss of vertical dimension- flaring of anterior teeth- non-working interferences
What are the 4 occlusal treatment goals?
- to direct occlusal forces along the long axes of the teeth (stable posterior contacts)- in MI position, all mandibular teeth should contact their maxillary opponents at the same time and with same intensity (CO=MI)- to furnish a smooth protrusive path guided by the anterior teeth without any interference from occlusal contacts between the posterior teeth (posterior disclusion)- working contacts (canine guidance or group function) should not be prevented from contacting by non-working interferences
True or false: Mounting accurate diagnostic casts to a semi-adjustable articulator permits static and dynamic relationships of the teeth without interferences from protective neuromuscular reflexes.
true
Where is a facebow placed?
13 mm anterior to tragus on tragus-canthus line
What is a pantograph used to pinpoint?
used to pinpoint actual hinge axis
What is the difference between kinematic and arbitrary hinge axis?
The kinematic is where the actual hinge is and arbitrary is anywhere within the circle around it???
What is the formula used to calculate Bennett’s angle?
Bennet/lateral angle = (h/8) + 12h = horizontal angle (25, 30, etc.)
What term is described by the following definition?the ideal relationship of posterior teeth when the mesiobuccal cusp of the maxillary first molar is centered on the buccal groove of the mandibular first molar
Angle’s class I occlusion
What term is described by the following definition?malocclusion in which the mandibular dental arch is posterior to the maxillary dental arch in one or both lateral segments; mandibular first molar is distal to maxillary first molar compared to the ideal class I relationship
Angle’s class II occlusion
What term is described by the following definition?malocclusion in which the mandibular dental arch is anterior to the maxillary dental arch in one or both lateral segments; mandibular first molar is mesial to the maxillary first molar compared to the ideal class I relationship
Angle’s class III occlusion
What term is described by the following definition?the influence of the contacting surfaces of anterior teeth on tooth-limiting mandibular movements
anterior guidance