Denture Pros Exam Flashcards
what is kennedy class 1?
bilateral free end saddle
what is kennedy class 2?
unilateral free end saddle
what is kennedy class 3?
bound saddle not crossing midline
what is kennedy class 4?
bound saddle crossing midline
why is reciprocation required?
to prevent tooth movement
what should a clasp be when seated?
passive
what dimensions are required for a mid palatal bar?
7-12mm
what materials should be used for a gingivally approaching clasp?
cobalt chrome or stainless steel
give a benefit of an I bar
puts less stress on the tooth
name other types of clasp deisgn
ring clasp
occlusally approaching clasp
3 arm clasp
what crown height is required for a dental bar?
9mm
what is the bar width and gingival/incisal clearance for a dental bar?
5mm bar width
2mm clearance from gingival margin
2mm clearance from incisal tip
give a benefit of a dental bar design over a plate design?
more hygenic than plate design
when should a dental bar not be used?
when there’s spacing between teeth
what is a distinctive feature of the lingual bar? what do these do?
cummer arms - they provide indirect retention to prevent a posterior uplift
what sulcus depth is required for a lingual bar? how much clearance from the gingival margin should the lingual bar have?
7mm sulcus depth required
lingual bar should be 3.5mm away from gingival margin
when is the use of a lingual bar advantageous?
when the pt has anterior spacing
what undercut depth would Co/Cr clasps be used for?
0.25mm
what undercut depth would SS clasps be used for?
0.5mm
what undercut depth would gold clasps be used for?
0.75mm
what clasp material is the least and most flexible?
Co/Cr is least flexible
Gold is most flexible
how is undercut gauge used and what does it determine?
undercut gauge drawn up against the tooth
where the gauge touches the tooth is the point where the clasp should terminate (where terminal 1/3rd of clasp engages)
how does finishing point of SS clasp compare to finishing point of Co/Cr?
SS clasp finishes further down tooth further away from the survey line - as more flexible and engages a deeper undecrut
name 3 types of articulator
- plane line
- average value
- semi adjustable w/ facebow - has measurements written on it
what incisal angle and condyle width is average value set to?
incisal angle of 10 degrees
average condyle width = 25mm
what does a facebow record?
to record the relationship between the maxilla and TMJ
list 4 advantages of injection moulding over dough packing
- no flash in injection moulding which minimises the risk of an open bite when fitting the dentures
- no trial pack
- less handling of material required
- less pressure when injecting material
list 5 disadvantages of injection moulding over dough packing
- need to add sprue
- extra training required
- expensive
- difficult to de-flask - as you have the sprue to contend with as well
- technique sensitive
how does flash thickness affect denture thickness?
inc flash thickness increases denture thickness
how does an open bite present on the articulator?
pin will not touch the table
what method increases the risk of an open bite/pin not touching the table? why?
dough packing - due to inc flash thickness
what 2 errors can cause contraction porosity?
not enough pressure on the mould
not enough material to fill the mould
what 2 things can cause gaseous porosity?
wrong curing cycle
heating too rapidly - causing the MMA monomer to boil
where in denture does gaseous porosity occur?
in the thickest part of the denture
what can occur if alginate impression is left in the disinfectant solution for too long?
Imbibition - absorption of one substance by another
what can occur when the alginate impression is not kept in a sealed bag with damp napkins?
Syneresis - alginate expulses liquid causing shrinking of impression
where is the hamular notch found?
behind the tuberosities of the maxilla
where is the raphe found?
running down midline of the palate
what does the willis gauge record?
the OVD
what does the Fox’s Guide Plane measure?
the level of the occlusal plane
when are flat cusped teeth used?
when the patient’s bite is non reproduceable
what material is used for soft linings?
molloplast
is it better to have a thinner or thicker soft lining? why?
better to have thinner soft lining
a thicker soft lining would mean less acrylic on the denture which would weaken the denture
when is a denture rebase required? (2)
when the denture is loose fitting
when teeth are worn or loose
what should be done to the denture prior to taking a wash impression?
remove undercuts
when is a closed bite technique used?
to avoid occlusal errors such as an open bite
how is closed bite technique used?
wash placed over fitting surface of denture and placed into mouth - pt bits down
what indicates that the mould is full during injection moulding?
resin exits the mould as the clamp handle is turned and piston pushes resin into the mould
what type of clasps is undercut gauge used to select material for?
occlusally approaching
what term is used to describe the change in length of a specimen?
ductility - a materials ability to be stretched/pulled
what term is used to describe an elongated specimen?
tensile specimen
what force is required to flatten a specimen?
compressive force
what term is used to describe the hardness of a material?
modulus = stiffness of material
what force is applied to a mid beam to fracture it?
3 point flexural strength
label the medial pterygoid
runs vertically
label the buccinator
underneath masseter - runs from mouth posterior to medial pterygoid
label the condyle
posterior to coronoid
label the obicularis oris
around mouth
label the nasalis
over nose
label the masseter
superficial to buccinator
exits zygoma and inserts into angle of mandible
label the zygomaticus major
runs from zygoma down to orbicularis oris
label the temporalis
flat on lateral of skull - inserts down into zygoma
label the coronoid process
anterior to condyle
label the mental nerve
runs down onto chin
what is dental gypsum used for?
impression plaster, dental plaster and dental stone - study casts
list 3 non elastic impression materials
impression plaster
impression compound
zinc oxide eugenol
cannot record undercuts so only use in edentulous areas
what is alginate used and not used for?
used for - study models, removable partial dentures, for temporary crown/bridges, creation of special trays, mouth guards, bleaching trays
not used for crown and bridge definitive restorations as bad detail
name 4 non-aqueous elastomeric impression materials (hydrophobic)
polysulfides - good for big undercuts (inlays, crowns, bridges)
polyethers - avoid in big undercuts (crowns, bridges, partial dentures and implants)
condensation silicones
addition silicones
what is zinc oxide eugenol impression material used for?
secondary impressions for complete dentures
what is alginate used for?
primary impressions for dentures
opposing arch impressions for crowns/bridge models
what are polysulphides used for?
complete dentures - long working time required
what are polyether used for?
final impressions for crowns, bridges, partial dentures and implants
avoid in deep undercuts and bridges
what is addition and condensation silicone used for?
crowns, bridges, partial dentures and implants
name 2 aqueous elastomeric impression materials (hydrophillic)
alginate and agar
