Fixed Exam 1 Flashcards
What is Mutually Protected Occlusion?
Posteriors protect anteriors and vice versa
How do posterior teeth protect anterior teeth from a design perspective?
(3 things)
Posteriors have more roots
Occlusal table is larger
Orientation of the teeth is oriented along the vertical axis
How do anterior teeth protect posterior teeth?
Disengage posterior teeth in mandibular excursive movements (canine guidance) - LONGEST ROOT
Moves fulcrum forward (less force)
Muscles
Why is it important to disengage the posterior teeth in excursive movements?
Prevent cusp breaks
The disengagement of posterior teeth in mandibular excursive movements is done by…
Canine guidance
When multiple posterior teeth are touching, this is called…
Group function
maximum intercuspation
How are anterior teeth designed to protect posterior teeth?
Canine has LONGEST ROOT and therefore takes lateral forced better
Fulcrum
Muscles - reduction of elevator mm. activity
How does moving the contact point anteriorly effect the force applied to the tooth?
Further away from fulcrum, the less force applied
When occlusal forces are moved forward to the anterior teeth, what feedback shuts off elevator muscles to decrease force?
Proprioceptive from the PDL
What discludes the posterior teeth in laterotrusive movements?
What discludes the posterior teeth in protrusive movements?
Canines
Incisors
Occlusal trauma is defined as exceeding the adaptive and reparative capacity of the _______
peridontium
Abnormal/Excessive occlusal forced acting on the teeth with Normal periodontal support
Primary Occlusal Trauma
Primary occlusal trauma can be from a barfight or ….
Iatrogenic
*filling too high
Normal occlusal force with decreased periodontal support is _____ Occlusal Trauma
Secondary
What are the 4 signs/symptoms of occlusal trauma?
Pulpitis
Mobility
Fremitus
Widened PDL
What is the difference between Mobility and Fremitus?
Fremitus is vibration in occlusion (more vibration than adjacent tooth)
*Fremitus can lead to mobility
Average width PDL:
0.17 mm
Class I tooth mobility:
Class II tooth mobility:
Class III tooth mobility
0.2 to 1 mm
greater than 1 mm
greater than 1 mm + axial displacement
How would you treat Primary occlusal trauma?
Reduce forces
*back to MPO
How would you treat Secondary occlusal trauma?
Splint teeth (sharing forces)
*cross-arch stabilization
If all posterior teeth are removed you are likely to see….
Primary Occlusal Trauma
The mesial buccal cusp of a Mandibular tooth occludes with the ______ of the corresponding maxillary tooth.
MMR - mesial marginal ridge
The distal buccal cusp of the Mandibular tooth occludes with _______ of the corresponding maxillary tooth
Central Groove
Where do the maxillary functional cusps occlude?
Buccal of lower
T/F
Cusp to marginal ridge can either be to one or two marginal ridges
True
What is the most natural type of occlusion found in 95% of adults?
Cusp to marginal ridge
What is the advantage to Cusp to Fossa?
forces near center of tooth and very little lateral forces
What are the disadvantages to Cusp to Fossa?
Rarely found naturally
What are the disadvantages to Cusp to Marginal Ridge?
Food impaction
When would you restore teeth to Cusp to Fossa relationship?
Cusp to Marginal Ridge?
Full mouth reconstruction
Daily
T/F In class we had a minimum of 3 bilateral posterior and three anterior contacts (canines plus 1 incisor)
True
T/F
Always deepen fossa, not functional cusps
True
T/F
Maintain triangular/marginal ridges by adjusting mesial/distal slopes as well as ridge
True
Why would we adjust the Lingual of the Maxillary anteriors before the incisal edge of the Mandibular anteriors?
Phonetics
BULL rule:
Buccal of Upper Lingual of Lower
*adjust these
When does a tooth need a crown (3 reasons)
Tooth structure (loss compromises integrity)
Esthetics
Change contours (Survey Crown- supports a removable partial denture)
What causes the loss of tooth structure?
5 things
Caries
Attrition (bruxism) - grinding by friction
Abrasion (toothbrush) - mechanical process
Abfraction (load, flex, cervical area)
Erosion - chemical (acids) intrinsic/extrinsic
Critical pH
5.5
Composition of Enamel in dentin
70%
An MOD loses ___% of structural integrity
70%
MOD then endo is stronger
True
Erosion often concentrates where (intrinsic)
Lingual Max anteriors
What type of crown supports a removable partial denture?
Survey Crown
What are the 6 steps to crown making a crown?
Preparation - Grind tooth circumferentially (crown prep)
Impression - mold (make)
Mount - turn impression into stone CAST, put on articulator
Wax up
Investment
Casting - burn off wax and fill space with metal
***porcelain cast for last step
VDR:
VDO:
Vertical Dimension of Rest
Vertical Dimension of Occlusion
When adjusting the anteriors you’d rather adjust the linguals of the maxillaries than the incisal of the mandibular for what 2 reasons?
Closest speaking space
Esthetics
Difference between VDR and VDO =
2-3mm
For the typodont adjustment there was a minimum of 3 bilateral posterior contacts _____ molar, _____ premolar
2 molars
1 premolar
For the typodont adjustment there was a minimum of 3 anterior contacts - what were they?
Canines and 1 incisor
The BULL rule is used in adjusting Laterotrusive movements, what is used when adjusting protrusive movements?
MUDL
Mesial of Upper, Distal of Lower
*adjust these
What are the 3 primary functions of an impression tray?
Carry
Confine
Control
What is the most expensive item in making impression?
PVS - polyvinyl impression material
Boxing was is how wide?
2.5mm
Stop dimensions on a tray should be 2-3 mm towards the central groove on the buccal of # __ and #___
2
What are the 3 larger principles to keep in mind while making your preparation?
Biologic
Esthetic
Mechanical
A crown preparation must be much larger if the pt is young b/c the _________
pulp is larger
Pulpal insult depends on pt age, whether _____ is used, and type of crown.
water
What are 2 reasons a preparation for a porcelain fused to metal crown needs at least 1.5 mm?
Color
Strength
There is always a bevel on the _______ cusp in a crown prep.
Functional
A chamfer forms a ______ angle
A shoulder forms a _____ angle
obtuse
right angle
The obtuse chamfer is made from _____ and measures ____ mm
The right angle shoulder is made from _______ and measures ______ mm
metal, 0.5mm
porcelain, 1.2mm
The chamfer is cut with the _____ bur and is _____ mm wide at the tip
The shoulder is cut with the _____ bur and is _____ mm wide at the tip
856, 1.0mm
KR6847, 1.2mm
Porcelain is strongest when it is under _______
compression
*so portion should rest on flat surface
Retention form resists dislodgment in a _____ dimension
parallel
Resistance form resists dislodgment is in a ______ dimension
NOT parallel
*any other axis
Occlusal convergence is related to Retention in a _______ manner
non linear
*more angle, drops off drastically
Height of the prep is important for ________
Resistance
The higher the _______ ratio, the better Resistance form we have
Height to Base
*the narrower and taller, the better the resistance form
Do incisors or molars have better Resistance form in a prep?
Incisors
*better height to base ratio (won’t know over easily)
T/F
A groove in a crown prep effectively increases the height to base ratio
(decreases base measurement)
True
If the path of placement (draw, path of withdraw) is askew enough it will create an _______
undercut
A negative imprint of an oral structure used to produce a positive
Impression
Materials: An impression must be sufficiently ________
viscous enough to be _______
able to set to a rubbery/rigid consistency in less than ____ minutes
Also dimensionally stable (PVS is good, Alginate is ____)
Biocompatible
Cost effective
fluid
contained in tray
7
bad
What material is used for making impressions?
Elastomeric
A material that can return to its original form when stressed:
Elastic
The opposite of elastic:
Plastic
Plaster, compound, WAXES, and zinc eugenol are….
non-elastic
What are the 2 types of Elastic materials?
Aqueous hydrocolloid
Non-aqueous elastomers
What are 2 types of Aqueous Hydrocolloid materials?
Agar (reversible)
Alginate (irreversible)
What are 3 types of Non-aqueous elastomers?
Polysulfide
Polyester
Polyvinyl siloxane (PVS)
What are the two types of reactions PVS (polyvinyl siloxane) can go through?
Condensation - EtOH byproduct
Addition
When using PVS, what is the preferred type of reaction to use?
Why?
Addition
*no EtOH (no byproduct whatsoever)
Strain is the change in ______
Stress is the ____ applied
distance
force
**if elastic, will be linear
Working time is when the impression material can be fully ______ without distortion
Setting time is when the material is firm enough to resist _______
seated
permanent deformation
T/F
Working time is around 2.5 minutes, Setting time is around 7 minutes
True
T/F
The set time in the mouth for impression material is faster because it is warmer
True
The property of material that exhibits both viscous and elastic characteristics when undergoing deformation
Viscoelastic
*there is a time dependent strain
PVS is a material that is both _____ and ______
This means there is a _____ dependent strain
viscous, elastic
time
T/F
With PVS, the faster you remove the impression the less it distorts. You should remove it with a snapping motion
True
A time-dependent shear thinning property (aka, time-dependent viscosity):
*PVS has some of this property - if stressed will flow at the beginning)
Thixotropic
this is the solid and liquid thing the kid was holding in his hand
What are the 2 reasons for retraction cord?
Hemostasis (fluid control)
Create space for impression matl into sulcus
T/F
Retraction cord is typically soaked in a hemostatic agent
True
Two brand names for the vasoconstrictor soaked retraction cord are Hemodent and Viscostat Clear and contains 25% _______
Aluminum Chloride
*a vasoconstrictor
Irreversible hydrocolloid
Alginate
Our provisional material is a _______ composite resin
Bis-Acryl
T/F
Bis-Acryl material for our provisional is a low exothermic, low shrinkage, good esthetic, bad brittleness, less stain resistant, limited shades, and cost is bad
True
T/F
Smaller cord is 000 or 00 and larger is 0.
True
Retention, think…
Resistance, thin…
parallel walls
height to base ratio
Which will be the larger number, VDR or VDO
VDR - rest
T/F
In protrusion there are only 2 reasons anterior protect posterior b/c incisors don’t have longest root like canines do
True
Why does the functional cusp need to be beveled?
Bigger bulk around absorbing load.
T/F
One disadvantage to a shoulder is making it smooth
True
T/F
Unused alginate should be stored in a ziplock so that it remains at 100% humidity
True
What is the custom tray material?
What is the photoinitiator wavelength?
UDMA - Urethane dimethacrylate
UV
What is the purpose of adding adhesive to the triple tray?
Prevents material distortion by separating from tray
856 bur has a ____ mm chamfer
the KR bur is for the _____
6 is rough and ____ is fine
1.0 mm
shoulder
8
The triple tray captures the opposing arch, the prep, and jaw ______
relation
The triple tray captures the opposing arch, the prep, and jaw ______
relation
You need to ______ the mock tooth before making an impression.
Equilibrate
