DMS Flashcards
name three extrinsic causes of tooth discolouration
smoking
chlorhexidine
iron supplements
name three intrinsic causes of tooth discolouration
fluorosis
tetracycline
non-vitality
what are the two types of tooth whitening
external vital bleaching
internal non-vital bleaching
how does bleaching work on external vital tooth whitening
the discolouration is caused by chromogenic products produced
bleaching oxidises the compounds
leads to smaller and less pigmented compounds
what is the active agent in external tooth bleaching
hydrogen peroxide
name three constituents of bleaching gel used in dentistry
carbamide peroxide
carbopol
urea
what does carbamide peroxide break down to produce
hydrogen peroxide and urea
what is the use of carbopol in tooth whitening agents
thickening agent so it stays on teeth
name four factors that affect tooth bleaching
time
cleanliness of tooth surface
concentration of solution
temperature
name four warnings to consent the patient on before undertaking tooth whitening
sensitivity
relapse
colour of restorations
might not work
what are advantages and disadvantages of in-office tooth whitening
controlled by dentist
can use heat/ light
expensive
results wear off
what is the maximum strength of home tooth whitening remedies
6% hydrogen peroxide
how short should teeth whitening thermoplastic trays stop of the gingival margin
1mm
what are the instructions for at home bleaching of teeth
brush and floss
load tray with 1mm dot buccally on each tooth
keep in place for at least 2 hours
name four examples of when tooth whitening might be indicated
age related darkening
mild fluorosis
post smoking cessation
tetracycline staining
how long does it take for sensitivity of bleaching to wear off
2-3 days post bleaching
what clinical complication does tooth whitening present
problem with bonding later
residual oxygen from peroxide remains on enamel
name three indications of internal bleaching
non-vital tooth
adequate RCT
no apical pathology
what are two contra-indications of internal bleaching
heavily restored tooth
staining due to amalgam
name a risk of internal bleaching
external cervical resorption due to diffusion of hydrogen peroxide through dentine into periodontal tissues
what has to happen to RCT treated teeth when undertaking internal bleaching
remove GP from pulp chamber and 1mm below ACJ
place 1mm RMGIC over the GP to seal canal
why is RMGIC added to RCT treated teeth in internal bleaching
to seal dentine and prevent root resorption
what is the procedure for internally bleaching teeth
remove filling from access cavity
remove GP from pulp chamber and 1mm below ACJ
place RMGIC over GP
remove dark dentine
etch
place 10% carbamide peroxide in cavity
cotton wool
GIC
how many visits does it usually take to reach desired colour with internal whitening
3-4 visits
after 4 visits and no change - it isn’t going to work
after how many years should internal bleaching be retreated
every 4-5
what is microabrasion
removes discolouration limited to outer layers of enamel
what is the procedure for microabrasion
clean teeth and rubber dam
18% HCl and pumice
apply to teeth with prophy cup
5 seconds per tooth
wash
repeat 10 times
polish teeth with fluoride prophy paste
apply fluoride gel
when should microabrasion be reviewed
after 1 month
name advantages of microabrasion
quick
easy
no long term problems
name disadvantages of microabrasion
acid
sensitivity
only works for superficial staining
what products cannot be used for anyone under 18 unless intended for preventing disease
0.1-6% hydrogen peroxide
what affects your judgement for the restorability of teeth with composite
if tooth can be isolated well with dental dam
if subgingival = cannot achieve
sub alveolar cavities/ vertical root fractures = unrestorable
what is the purpose of camphorquinone
releases free radicals when attacked by blue light which allows addition polymerisation in the resin
what is the action of the resin and what material is this usually in composite
usually bis-GMA
allows further cross linking of the C-C double bonds which increases molecular weight, strength and viscosity
what is the action of filler in composite
increases compressive strength, abrasion resistance and fracture toughness
name two materials that filler in composite can be
lithium aluminosilicate
borosilicate
what is the purpose of low-weight di-methacrylates in composite
used to adjust viscosity and reactivity
what is the purpose of silane coupling agent in composite
bi-functional molecule that increases bond of resin and filler particles
name the five components of composite
camphorquinone
silane coupling agent
filler
low weight di-methacrylates
resin
what is the purpose of acid etching
37% acid which is used to remove the smear layer and allow enamel bonding
what are millers forceps used for
for holding articulating paper
what is flowable composite used for
useful for filling small voids
how should you choose a composite shade
without rubber dam (due to dehydration occurring after placement)
check shade with and without operating light
involve patient in the selection process
check contralateral and adjacent teeth
what are the overall shades for the different letters for shade matching composites
A - brown
B - yellow
C - grey
D - red
what material is used to take a putty matrix
polyvinylsiloxane
what is the purpose in incorporating a bevel in a cavity
increases surface area for bonding - cuts dentinal tubules on their longitudinal long axis which improves bonding
how does enamel etching work
selectively dissolves enamel rods to create porosities so the resin can penetrate
what is a smear layer
created when dentine is cut by hand or rotary instruments - thin layer of cutting debris, saliva and bacteria
what is the hybrid layer
layer created when resin infiltrates the surface layer of dentine - strong bond between resin and dentine forms when monomer penetrates dentine
what is the function of HEMA
bi-functional molecule used to prime dentine
what are the two main types of dental adhesive systems
etch and rinse
self etch
what occurs in the etch and rinse systems
smear layer removed by acid etch exposing the dentinal tubules
what occurs in self etch systems
simultaneously condition and prime enamel and dentine - smear layer is penetrated by self etch primer which infiltrates smear layer and smear plugs
three actions of phosphoric acid
removes smear layer
demineralises the dentine
exposes collagen fibres
three actions of dentine bonding agents
remove remaining water
prime dentine for resin infiltration (HEMA)
allow resin to fill spaces between collagen fibres
what is the percentage of monomer to polymer conversion of composite
60%
what light range is required for camphorquinone to be activated in light cure composite
430-490nm
what are the free radicals in self cure composites that come as 2 pastes
tertiary amine
benzoyl peroxide
what is C factor in relation to composite
configuration factor
ratio of bonded to unbonded surfaces in a cavity and affects shrinking stress
name six complications of composite
moisture control
over manipulation
over/ under etching
polymerisation contraction shrinkage stress
low wear resistance
longer to place
why is moisture control required when placing composite
resin composites are hydrophobic - if contaminated this reduces the bond strength between composite and tooth
what is the main problem of over manipulation of composite
incorporates air and therefore porosities within the restoration
what is the problem of over-etching
causes collapse of the collagen framework so resin cannot penetrate to full depth
what is the problem with under etching
not enough enamel has been demineralised for penetration
name three effects of polymerisation contraction shrinkage stress
bond failure
cuspal deflection
post op sensitivity
