Sessions 1-4 (Quiz One) Flashcards
Define Fix Prosthodontics
The branch of prosthodontics concerned with the replacement and/or restoration of teeth by artificial substitutes that are not readily removed from the mouth.
What is the masticatory system responsible for?
Chewing, speaking and swallowing
What is the masticatory system made up of?
Bones, joints, ligaments, teeth and muscles
What does the neurologic controlling system of the masticatory system do?
Regulates and coordinates all the structural components
Define mutually protected occlusion
An occlusal scheme in which the posterior teeth prevent excessive contact of the anterior teeth in maximum intercuspation, and the anterior teeth disengage the posterior teeth in all mandibular excursive movements.
Posterior teeth protect _____ teeth
Anterior teeth
Anterior teeth protect _____ teeth
Posterior teeth
How do posterior teeth protect anterior teeth?
Posterior teeth prevent excessive contact of the anterior teeth in maximum intercuspation
Since the teeth are constantly receiving occlusal forces, what is put in place to help control these forces?
Periodontal ligament is present between the root of the tooth and the aveolar bone
The periodontal ligament runs ____ from the cementum, extending ____ to attach in the alveolus
Obliquely; occlusally
When force is applied to a tooth, what does the PDL do?
Support it
What can osseous tissue not accept? What stimulates bone formation?
Cannot accept pressure.
Tension stimulates bone formation
What does the PDL convert pressure into?
Able to convert a destructive force (pressure) into an acceptable force (tension)
The PDL can be thought of as a ______ ____ ____ controlling the forces of occlusion on the bone.
Natural shock absorber
Define axial loading
Process of directing occlusal forces through the long axis of the tooth
Where should tooth contacts be located that are ideal for loading?
On either cusp tips or relatively flat surfaces that are perpendicular to the long axis of the tooth
What flat surfaces are ideal for tooth contacts?
Crests of marginal ridges or the bottoms of fossae
With ideal contacts, the forces will be directed through the __ ___ of the tooth
Long axis
What are three ways posterior teeth protect anterior teeth?
Number of roots
Occlusal table
Orientation of teeth
How does the body allow the PDL to accept damaging forces to the bone and reduce them?
With vertical loading to eliminate off-axis forces
What should the tooth be contacted with so that the resultant force is directly vertically through its long axis and accepted by the PDL?
When the tooth is contacted on a cusp tip or a relatively flat surface such as the crest of a ridge or bottom of a fossa
How does the number of roots help posterior teeth protect anterior teeth?
The increased root surface allows for greater dissipation of force through the PDL when loaded in the vertical direction.
Describe how an occlusal table can help posterior teeth protect anterior teeth?
The wider occlusal table of posterior teeth is ideal for the absorption of transfer of force down to the root and underlying bone
How is orientation of teeth different in posterior teeth compared to anterior teeth
Posterior teeth: oriented vertically -> force applied along long axis of tooth
Anterior teeth: Generally oriented off axis from each other
How can anterior teeth protect posterior teeth in movement?
Disengage posterior teeth in all mandibular excursive movements
Which tooth has the longest root?
Canines
Which tooth is best suited to accept horizontal forces that occur during eccentric movements?
The canines
What type of bone are canines surrounded by compared to posterior teeth? How does this help the canines?
Canines: Compact bone
Posterior teeth: Medullary bone
Helps canines tolerate forces better than medullary bone on posteriors
Describe the difference in muscle movement with canines compared to posterior teeth?
Fewer muscles are used when canines make contact during eccentric movement than when posterior teeth come in contact.
Lower levels of muscular activity decrease forces to the dental and joint structures, thus minimizing ______
Pathosis
What occurs when a tooth is contacted on an incline?
Resultant force is not directed through its long axis -> causes tipping
What percentage of the general population has bilateral canine guidance?
26%
What is the most favorable alternative to canine guidance?
Group function
What happens during group function?
Several of the teeth on the working side make contact during the laterotrusive movement
What teeth are part of the most desirable group function?
The canine, premolars and sometimes the mesiobuccal cusp of the first molar
Why are laterotrustive contacts that are more posterior than the mesial portion of the first molar not desirable?
Because of the increased force that can be created as the contact gets closer to the fulcrum (TMJ)
Why is group function more common among older people?
Most likely due to canine wear
When is group function considered acceptable?
When it does not show any signs and symptoms of occlusal trauma
What are three ways anterior teeth protect posterior teeth?
- Longest root
- Location
- Muscles
What two movements do the central incisors separate the posterior teeth and canines?
- Posterior teeth -> Protrusive movement
2. Canines -> Lateral movements
What feedback loops helps protect posterior teeth from being overloaded?
Proprioceptive feedback loop
Describe the teeth’s position during protrusion
Anterior teeth separate posterior teeth
Describe teeth’s position during lateral excursion
Canine separate the posterior teeth
Define optimum occlusion
Uniform contact of all teeth around the arch when the mandibular condylar processes are in their most superior position
Optimum occlusion: Stable posterior tooth contacts with _____ directly resultant forces
Vertically
Optimum occlusion: Centric relation with ____ intercuspation
Maximum
What should not be contacting in lateral or protrusive movements?
Posterior teeth
Define occlusal trauma
Trauma to the periodontium from functional or parafunctional forces causing damage to the attachment apparatus of the periodontium by exceeding its adaptive and reparative capacities
Describe primary occlusal trauma
Abnormal or excessive occlusal forces on teeth with normal periodontal support
Describe secondary occlusal trauma
Effects induced by normal occlusal force acting on teeth with decreased peridontal support
What are four signs and symptoms of occlusal trauma?
Pulpitis, mobility, fremitus, widened PDL
Average width of PDL
0.17 mm
Class One Tooth Mobility
> 0.2 mm but < 1.00 mm
Class Two Tooth Mobility
> 1.00 mm
Class Three Tooth Mobility
> 1.00 mm+ Axial Displacement
What three things can occur in primary occlusal trauma?
Loss of posterior support
Bone Level loss
Flaring of anterior teeth
How would you treat primary occlusal trauma?
Reduce forces
What is a classic example of primary occlusal trauma? How is it solved?
Patient has new restoration in hyperocclusion. Solution: Adjust tooth so that occlusal force is evenly distributed among all the teeth.
What occurs in primary occlusal trauma with many missing posterior teeth? Solution?
Leads to overloading of anterior teeth -> Restore posterior support by adding teeth to missing spaces
How could you treat secondary occlusal trauma?
Splint teeth
How can spliting teeth solve secondary occlusal trauma?
Share/distribute the force among the teeth-> can stabilize compromised teeth
What are the functional cups of the mandibular teeth?
Buccal cusps
The most mesial buccal cusp of the mandibular tooth occludes with what?
MMR of its corresponding maxillary tooth
The distal buccal cusp of the mandibular molar occludes with what?
Corresponding maxillary tooth
What are the functional cusps of the maxillary teeth?
Lingual cusps
The most distal lingual cusp of the maxillary tooth occludes with?
The DMR of the corresponding mandibular tooth
The mesial lingual cusp of the maxillary molar occludes with?
The central groove of the corresponding mandibular tooth
Describe Tripodized contacts
Three points of contact which function to stabilize the tooth
Where do Tripodized contacts occur? What do the function as well as?
Occur on a cusp incline.
Function as well as holding cusps
Define Axial loading
Process of directing occlusal forces through the long axis of the tooth
Describe the first method of achieving axial loading.
Development of tooth contacts on cusp tips or relatively flat surfaces that are perpendicular to the long axis of the tooth.
Describe how axial loading is achieved through tripodization
Requires that each cusp contacting an opposing fossa can be develop to produce three contacts surrounding the actual cusp tip.
Describe incline contacts
Teeth that occlude on inclines without tripodized contacts.
Why are incline contacts not stable?
Because they can cause teeth to shift
What is the main goal of typodont adjustment
Develop a stable occlusal relationship between the upper and lower members
What are two types of rocking you don’t want in Typodont adjustments?
Anteroposterior or mediolateral rock
Typodont Adjustment: How many bilateral posterior contacts do you want? How many premolar/molar?
Minimum of five bilateral posterior contacts
3 molar
2 premolar
Typodont Adjustment: How many anterior contacts do you want? How many canines/incisors?
Four
Canines bilaterally
2 Incisors
Typodont Adjustment: Canines should contact only in ______ movements
Laterotrustive
Typodont Adjustment: What types of movements should canines not contact during?
No laterotrusive or mediotrustive posterior movements
Typodont Adjustment: A minimum of ___ anterior contacts with incisors end to end in protrusive movement, no posterior contacts bilaterally in protrusion
2
When adjusting contacts, do not shorten ___ ____. Instead, deepen the corresponding ____
Functional cups; Fossa
When adjusting contacts, adjust a prematurity on a triangular or marginal ridge by adjusting the mesial and distal +++++
Slopes
When adjusting contacts, for anterior prematurities, adjust the lingual of _____ _____
Maxillary anteriors
When adjusting contacts, why do you not want to adjust the incisal edges of the mandibular anterior teeth?
Phonetics or incising ability may be affected when mandibular incisal edges are altered
When adjusting contacts, what should be done if both functional cusps are contacting each other?
You can choose either cusp incline to adjust
What are three reasons why a tooth needs a crow?
Tooth structure
Improve esthetics
Change contour
Why does loss of tooth structure need a crown?
Loss of tooth structure compromises its structural integrity, necessitating cuspal coverage for protection.
What are five things that can cause loss of tooth structure?
Caries Attrition Abrasion Abfraction Erosion
Define caries
Infectious microbiological disease of the teeth that results in localized dissolution and destruction of the calcified tissues
Define attrition
Act of wearing or grinding down by friction
Where does attrition occur? What is it limited to?
Mechanical wear resulting from mastication or parafunction.
Limited to contacting surfaces of the teeth.
Attrition is grinding down by _______
Friction
Define abrasion
Wearing away of a substance through some unusual or abnormal mechanical process
What causes abrasion?
Caused by something other than mastication.
Brushing, nail biting, chewing on a pencil
Abrasion is an ____ mechanical process
Unusual or abnormal mechanical process
Define abfraction
Pathologic loss of hard tooth substance caused by biomechanical loading forces
Abfraction is caused by ____ loading forces
Biomechanical
Define erosion
An eating away; type of ulceration
Erosion is a loss of tooth substance by _____ processes
Chemical
What does improving esthetics help with?
Addresses the patient’s dissatisfaction with the color and contour of their teeth.
Define survey crown
Crown that supports a removable partial denture
Crown Prep: Grind tooth _______ and on top
Circumferentially
How to make a Crown Steps
Prep Impression Mount Wax up Investment Casting Porcelin
Crown Prep: Impression step
Make a mold of what the tooth looks like
Crown Prep: Mount step
Turn impression into stone and put it on an instrument that stimulates the movements of the mouth
Crown Prep: Wax Step
Add and carve wax until it looks like a tooth
Crown Prep: Investment Step
Pour investment around the wax pattern
Crown Prep: Casting Step
Burn off the wax and fill the space with metal
Crown Prep: Porcelain Step
Add porcelain to metal
Describe impression material
Polyvinyl siloxane is an elastomeric material that is hydrophobic by nature.
Why is Polyvinyl siloxane a good impression material?
Elastric recovery, surface detail and tear strength
Describe what Gypsum is
Dental stone
Type One -> Weakest
Type V -> Strongest
Expands upon setting
What are the three functions of a custom tray
Carry, confine, control
What does the use of a custom tray minimize?
Amount of impression material used
What is a light cured custom tray made out of?
Urethane dimethacrylate (UDMA)
What is a self cured custom tray made out of?
Poly methyl methacrylate (PMMA)
What are the two parts of liquid acrylic?
Monomer -> Methyl methacrylate
Activator -> Tertiary amine
What are the two parts of powder acrylic?
Pre-polymerized pmma beads
Initiator (Benzoyl peroxide)
What is the most common acrylic used in dentistry?
PMMA
What is used for dentures and temp crowns?
PMMA
PMMA ___ biocompatible
Is
Does PMMA shrink during polymerization process?
Yes
PMMA is ___thermic
Exothermic
What are Acrylic’s five distinct stages?
Sandy, stringy, doughlike, rubbery/elastic, stiff
Acrylic Material: Sandy Stage
No interaction on molecular level.
Beads are unaltered
Acrylic Material: Stringy stage
Monomer attacks polymer beads -> Polymer chains are formed -> increase viscosity
Acrylic Material: Doughlike stage
Increased number of polymer chains -> no longer tacky or sticky
Material should be inserted into mold cavity during latter phases of doughlike stage
Acrylic Material: Elastic stage
Monomer is dissipated by evaporation and by further penetration into remaining polymer beads
What is an advantage to using self-curing acrylic resin?
Resin provides strong and easily adaptable material to create a custom tray
What is a disadvantage to using self-curing acrylic resin?
Liquid monomer is very volatile and poses as a hazard
Define Chamfer
Gingival aspect meets the external axial surface at an obtuse angle
Define Shoulder
Gingival floor meets the external axial surfaces at a right angle
Why do you want to use a chamfer for metal and a shoulder for porcelain?
Can be used in non-esthetic areas Chamfer is more conservative Metal is stronger than porcelain Marginal seal is better with metal Porcelain is strongest under compression Porcelain needs more reduction to hide the metal
Define Retention
Quality inherent in the dental prosthesis acting to resist forces of dislodgment parallel to the path of placement
Define Resistance
Features of a tooth prep that enhance the stability of a restoration and resist dislodgement along axis other than path of placement
Define total occlusal convergence
Angle, measured in degrees, formed between opposing axial walls when a tooth or teeth are prepared for crowns.
Define undercut
Any irregularity in the wall of a prepared tooth that prevents the withdrawal of seating of a wax pattern or casting
Define path of placement
Specific direction in which a prosthesis is placed on the tooth
Provisional Restoration: What are five biological requirements?
- Protect pulp
- Maintain periodontal health
- Provide occlusal compatibility
- Maintain tooth position
- Protect against fracture
Provisional Restoration: What are three mechanical requirements?
- Resist functional loads
- Resist removal forces
- Maintain inter-abutment alignment
Provisional Restoration: What are four esthetic requirements?
Easy to contour
Color compatibility
Translucency
Color stability
Describe Temp-Bond NE
Will not inhibit polymerization of permanent resin cements and acrylic temporaries
Bis-acryl Advantages
Low exothermic reaction
Low shrinkage
Ease of dispensing
Short setting time
Bis-acryl disadvantages
High cost
brittle
Dissimilar chemistry w/flowable composite
Thick oxygen inhibited layer
Why is SNAP (PEMA) acrylic better than PMMA?
Safer intraorally
Does not traumatize pulp
Less polymerization shrinkage
