Clinical Composite Flashcards
factors to consider regarding use of composite
tooth biology
material science
interfaces
marginal seal
manipulation
polymerisation
why is the ADJ important when using composite
caries left at the ADJ will result in unsupported enamel and early breakdown of the restoration margin if micro leakage occurs
marginal integrity is compromised
what happens if there is poor enamel preparation at the margin
- the composite dimension will change
- etch is stronger than the interstitial enamel strength leading to enamel failure and micro leakage
which kind of dentine is favourable for hybrid layer creation
primary dentine as it is less mineralised and therefore the tubules are more open
why is tertiary dentine unfavourable for hybrid layer creation
it has an irregular structure
why is deeper dentine unideal for hybrid layer formation
it is wetter, meaning the moisture content is higher which the methacrylate will struggle to bond to
it is also more mineralised and has more tubules
what are the characteristics of older dentine
fewer tubules, more mineralised and occluded tubules
what are the characteristics of reactive dentine
occluded tubules, more mineralised and irregular tubules
how does poor quality dentine allow adhesion
through ion exchange
why are the linings in dentine relative to consider before bonding
can provide reason for placement, impact bonding, contaminate enamel
there are risks if micro leakage occurs and can lead to secondary caries
what are the most common issues with clinical composite
cavity preparation
bonding
contacts
placement
countering contraction stresses
to understand tooth tissue for bonding, which elements should be understood
material properties
cavity design
matrices
manipulation
configuration factor
polymerisation contraction stress
what is CF
cavity configuration factor - the ratio of bonded to unbonded surfaces, which is important for composite restorations
It’s used to predict shrinkage stress in the materials used for composite resin restorations. A higher C-factor indicates a higher risk of polymerization shrinkage stress, which can lead to problems like: Marginal gaps, Post-operative sensitivity, and Restoration failure
how does cavity configuration factor relate to polymerisation contractions stress
low CF means reduced polymerisation contraction stress
is bond strength greater than to etched enamel or to dentine
enamel
what is plasticity
a property of a material to undergo a non reversible change of shape in response to an applied force (polymerisation)
what is deformation
a change in shape due to an applied force (contraction)
what is polymerisation contraction
plastic deformation
draw the stress strain diagram
why is it important to build up composite
reduces chance of pain after restoration by reducing shrinkage - larger lumps shrink more
what do contoured bands allow
positioning of the contact better than flat bands
list the clinical procedure to a filling
etch
prime
bond
placement
characterisation
finish
why does enamel need longer etch time than dentine
because it is more mineralised
list the stages to a filling in detail
enamel etch for 10s
moist surfaces
dentine primer
adhesive application
at this point consider the need for flowable composite to mediate contraction stresses on interface and to achieve optimal adaption to non load bearing margins
1st increment on the floor only
successive increments touching as few surfaces as possible
the final increments should not join enamel margins, this is to give correct morphology as there are normally occlusal fissures
what is the minimum intensity required to adequately cure 1.5mm to 2mm of composite resin
in between 280 and 300 mW/cm2
check the light regularly
what are the different curing regimes
soft start
ramp
pulse
boost
delayed curing
why is it important that curing lights aren’t high intensity
the composite shrinks
function of high power curing light
fast curing
function of low power curing light
close to pulp curing
function of soft start curing
polymerisation with reduced contraction stress
mW/cm2 value for low power curing lights
650
mW/cm2 value for high power curing lights
1,200
what is the main reason for reduced shrinkage stress
decreased final conversion
what is shrinkage direction determined by
bonded surfaces and free surfaces
when does composite shrink toward the light
if the bonding fails
what is the value for the halogen like emission spectrum that polymerises all materials
380-515 nm
what are the steps to placing composite increments
sectional matrix and wedge in place
enamel etch
dentine and enamel etch
wash and remove excess moisture
bond placement and cure
flowable composite placement and cure
occlusal floor only composite increment, cure
mesio lingual wall, 1st increment placement to midpoint of contact, cure
mesiobuccal wall, second increment placement to midpoint of contact, cure
matrix removed and contact and gingival floor are checked
disto buccal occlusal increment placed and cured
mesiobuccal occlusal increment placed and cured
distolingual occlusal increment placed and cured
mesiolingual occlusal increment placed and cured
marginal finish and occlusal checked
final polish and surface seal
completed restoration
