Operative Dentistry Flashcards
what aspects of your cavity preparation should you consider for composite
prism orientation
avoid cavosurface margins
what is the result of caries being left at the EDJ
unsupported enamel and early breakdown of restoration margin when microleakage occurs
what is assessed with sensibility testing
the neural activity - not vascular supply
give an example of a vitality test
pulse oximetry - measures the blood flow
what are the four requirements for caries to develop
susceptible tooth surface
Time
Bacteria
Sugar
name four potential plaque traps on a tooth
pit and fissures
interproximal
smooth surfaces
root surface
what are reasons for treating tooth loss
aesthetics
function
speech
maintenance of teeth
what is a bridge
prothesis that replaces a missing tooth or teeth and is attached to one or more natural teeth or implants
what are the two types of bridgework
adhesive
conventional
what are indications for a bridge
favourable alignment of abutments
favourable occlusion
aesthetics
big teeth
what are contra-indications for a bridge
abutment prognosis poor
likely to lose more teeth in same arch
uncooperation
periodontal disease
tilted and rotated teeth
periapical status
what are the two designs that conventional or adhesive bridgework can be
cantilever - abutment tooth on one side
fixed-fixed - abutment teeth on both sides
what are advantages of cantilever bridges
minimal to no prep
no LA required
less surgery time
less costly
what are disadvantages of cantilever bridges
rigorous clinical technique
metal shine through
chipping porcelain
occlusal interference
what is required when canines are going to be used as part of the bridge unit
facebow registration
what is a direct bridge
done post XLA
using patient’s tooth
patient doesnt have to leave with a gap
what is an indirect bridge
lab formed
wing finish 0.5mm supragingivally
what preparation is required for an adhesive bridge (if needed)
180 wrap around
chamfer margin 0.5mm supragingivally
rest seats on posterior teeth
what retainers are used for resin bonded bridges
CoCr or NiCr
sanblasted by lab to increase bond of cement
what is an advantage of conventional bridgework
more robust
used in larger spans
maximum retention and strength
what are disadvantages of conventional bridgework
more destructive to tooth tissue
preparation is difficult
removal of tooth tissue
parallel tooth preparation required
what are the five aspects of pontic design
wash through
dome shaped
modified ridge
ridge lap
ovate
what materials can be used for abutment teeth crowns in conventional bridges
all metal - gold, nickel, CoCr, stainless steel
metal ceramic
all ceramic - zirconia, lithium disilicate
what materials may be used for crowns
gold type II alloy
paladium alloy
base metal alloys (nickel and chromium)
ceramic
stainless steel (paediatric)
when are crowns used
to protect weakened tooth structure
to improve aesthetics
for retainers in bridgework
when indicated by RPD design
to restore tooth function
what are the 6 principles of tooth preparation
preserve tooth structure
retention and resistance
structural durability
marginal integrity
preserve periodontium
aesthetics
what does under preparation for a crown result in
poor aesthetics
overbuilt crown with periodontal and occlusal consequences
what does overpreparation of a tooth for a crown result in
pulp and tooth strength being compromised
what is the ideal design of a crown to allow retention and resistance to unwanted forces
inclination of opposing walls 6 degrees
limit number of paths of insertion
how is the tooth prepared to be structurally durable for crown application
occlusal reduction
functional cusp bevel
axial reduction
for metal ceramic crown preparations on posterior teeth what is the occlusal reduction required
2.5mm
what is the occlusal reduction required for metal crowns
1-1.5mm
what margin is required for metal ceramic crowns
1.5mm chamfer margin
what occlusal reduction is required for all ceramic crowns
2.5mm
where should margins of crown restorations be placed to preserve the periodontium
smooth and fully exposed to cleansing action
where the dentist can finish them and patient can clean them
at the gingival margin where possible
what is the axial reduction, occlusal reduction and finish line for a metal crown
0.5mm axial
1.5 functional cusp
0.5 non-functional cusp
chamfer
what is the axial reduction, occlusal reduction and finish line for ceramic crowns
1mm axial
1.5mm functional cusp
1mm non-functional cusp
shoulder (1mm)
what is the axial reduction, occlusal reduction and finish line for a metal ceramic crown
1.3mm axial
1.8mm functional cusp
1.3 non-functional cusp
chamfer margin
what are the stages in tooth preparation for a metal ceramic crown
occlusal reduction
separation
buccal reduction (in 2 planes)
palatal/ lingual reduction
shoulder/ chamfer finish
check occlusal surface and clearance
what are three treatment objectives of treating an endodontically treated tooth
remain tooth in arch
maintain coronal seal of root canal system
protect and preserve remaining tooth structure
what is a post
peg or pin for fastening an artificial crown or core onto natural tooth root
when are posts required
when three walls are lost (MODB/L cavity)
no walls remaining
what is the minimum thickness of a cavity wall to determine resistance to functional loads
1mm
what is a ferrule
2-3mm coronal dentine remaining
should not be less than 1.5mm
what is the function of a ferrule
reduces stress which otherwise would cause root fracture
what are the dimensions of an optimal post
1: ratio with crown or 2/3rd root length
4-5mm GP left at apex
no more than 1/3 of root diameter
placed in straight part of canal
what materials can be used for posts
metal - stainless steel, titanium, cast metal
non-metal - glass fibre, cement fibre
what are cast posts
custom made posts to follow canal curvature
requires extra lab and clinical stage
what are fibre posts
pre-formed posts
tooth coloured
compatible with adhesive systems
when would a fibre post be used as opposed to cast post
for a fibre post there must be 2-3mm remaining supra-gingival tooth structure
fibre posts cannot be used in patients with paranfunctional habits or overbites
what is the mode of failure for 1) cast posts and 2) fibre posts
1) fracture roots
2) debond at post-cement interface leading to caries
what is the downside of tapered posts
must be cement retained
wedging effect
what is the downside of parallel posts
more tooth tissue removed
what are three aspects of an optimal post design
parallel sided - avoids wedging
non-threaded - avoids installation stress
cement retained - cement distributes masticatory forces
what types of cements can be used for cementing posts
GIC
adhesive resin cement
RMGIC
what are the properties of adhesive resin cements in post placement
greater retention
higher compression strength
premature setting may occur before post fully seated
what are the properties of GIC as a cement for post placement
weak chemical bond to dentine
easier retrievability
fluoride release but requires several days to reach max strength
what are the properties of RMGIC as a cement for post placement
insoluble
good retention
but expands with time
what is polyvinylsiloxane an example of
elastomeric material
what are the three viscosities PVS has
light bodied
medium bodied
heavy bodied
what forceps are used with articulating paper
millers forceps
what are two ways an apex locator reading can be affected
fluid within the canal
poor contact point with canal walls
