hi everyone in this video we'll be talking about resin-bonded bridges their indications
contraindications their design features and the clinical workflow from start to finish
so just before we get started we'd like to thank dr kushar guardia who is a consultant
in restorative dentistry and a specialist in periodontology prosthodontics endodontics
restorative dentistry and has a special interest in dental implantology dr guardia has been kind
enough to provide the content from ace courses and while this video is just a summary the full
webinar is available to students completely free of charge on his ace courses website
sign up link in the description we won't bore you by reading what you can see on the screen now so
if you would like to have a look at the advantages and disadvantages or the indications and
contraindications for a resin bonded bridge feel free to pause the video now i also quickly wanted
to mention the survival rate for resin bonded bridges are 80 at 5 and 15 years but the most
important factors were the operator's experience and the bridge design being a cantilever so moving
on to the design there are many three types that you can use a cantilever which is a pontic from
one abutment tooth a fixed fixed bridge which as the name describes is attached to two abutment
teeth and finally a hybrid which has a resin bonded wing or a retainer on one abutment tooth
and a crown or a conventional designed retainer which sits on the other abutment tooth so let's
start with a cantilever these are good when you have one missing tooth and want to replace the gap
it also has a reduced risk of secondary carries as compared to fixed fixed design the reason for this
is because if you have one winged retainer which debonds then that's that the bridge will just come
out and in terms of survival rates cantilevers last about 10 years and fixed fixed bridges last
about 8 years also when you have a fixed fixed design if one retainer d-bonds the other wing
will just keep the bridge in place and food and plaque will build up and get trapped under the
de-bonded wing and cause secondary carries however a cantilever is not preferred post-orthodontic
treatment because cases have been seen where the teeth adjacent to the pontic have rotated which of
course affects the aesthetics because of this it might be better to either use a fixed fixed design
or to use a nighttime retainer more than what the orthodontist has prescribed for you to wear the
second design we mentioned was the fixed fixed and this is the option of choice when you have
a longer span and need to replace multiple teeth for example if you had your premolars missing
in the upper arch you could place a wing on the three and an occlusal coverage retainer on the six
with the four and the five as pontics as shown on the screen right now again they're also good
post orthodontic treatment but they have a higher chance of secondary carries if you get a partial
debonded retainer so now for the hybrid design that can come with a male and female component
which allows for some freedom in movement it also benefits us in that if one retainer debonds then
you can just remove the male component remake the new pontic with a new retainer and slot it back to
the crown without having to take the crown off a fourth design that we'll quickly mention is called
a spring cantilever and these are used for when the adjacent teeth to the gap that you want to
replace are compromised before we move on to the next section we'd really appreciate it if you guys
gave this video a thumbs up it really helps our channel grow and reach more people thank you one
ideal feature that you should aim to incorporate into your bridge design is maximum coverage
for better bond strength and you can do this by extending your retainer just short of the insides
or edges measly distally and right down only just super gingivally to allow cleanseability in the
area posteriorly we should be doing a fixed fixed design and we should be aiming for full
occlusal coverage the reason is because when you do partial occlusal coverage the occlusal forces
in lateral excursion can cause the retainer to shear off another ideal feature is to ask for
the retainer to be a minimum of 0.7 millimeters thick to prevent the warping of the retainer the
design should ensure that it is cleansable which means the patient should be able to feed some
super floss underneath the pontic and in terms of occlusion we want to have a holding contact
on the pontic which means they do contact an icp but we want to avoid all protrusive or lateral
excursive contacts you may have come across cases where an opposing tooth has over-erupted this is
why it's important to check the occlusion how could we create space in this area the options
are to use a dial approach orthodontic intrusion enamoplasty or a combination of these together
to create the space needed to restore the missing space you also want to look at the abutment teeth
and check them both radiographically with a periapical radiograph and clinically with
sensibility testing you also need to consider the patient's lip line at rest and when they smile
and if the case is post orthodontics and finally for abutment selection which tooth would you
cantilever from let's say you're replacing an upper lateral incisor would you use the central
incisor or the canine the answer is if both are not compromised in any way you would choose the
one with more enamel surface area to bond to although this is less important you should
also be considering the wrap around from mesial to distal of the tooth in this case of course
the canine would have more wraparound but if the central incisor had a larger enamel surface area
to bond to you would use this instead make sure to be cautious of the metal retainer showing through
the incisor to prevent this make the incisal edge of the retainer just short of the incisal
edge of the tooth so that we don't compromise the aesthetics we can also use an opaque cement
like panavia to block out the color of the metal wing the evidence by king at al 2015 leans towards
not preparing teeth at all and says that there is little benefit in doing so tooth preparation
is irreversible and so should be avoided in the name of minimally invasive dentistry it's
justifiable if you need to make mesial and or distal guide planes so that you can have a path
of insertion for the retainer some people prepare a margin but the enamel is thin and removing it
may very easily expose dentine reducing the bond strength massively it would be better to stick
the retainer in high by adding 0.7 millimeters of thickness then to remove tooth tissue the
surrounding teeth will very quickly adapt to this new occlusal height by darling in this is a case
example of this happening you can see in this photo that the canines are in contact and so
adding the 0.7 millimeter retainer will open up the bite you can see this on the study cast here
and then six months later when the occlusion was reassessed the posterior teeth have dialed in
and close the posterior separation one example of when you should prepare a tooth is if it had an
old restoration let's say you wanted to replace a gap in the upper left five by using the upper left
four and upper left six as fixed fixed abutment teeth and let's say the upper left six had a class
two media occlusal restoration you should replace the restoration with another composite to ensure
that there isn't secondary carries happening underneath and then you want to create a mesial
recipe like you would for a partial denture this would increase the rigidity of the connection
between the retainer and the pontic by increasing the thickness of the metal in that area this will
also allow more favorable bonding to the resin cement and enhance the retention of the bridge
something else to consider is the preparation of the pontic site with electrosurgery or a dry
high-speed bur when there is excessive gingiva in the area you can draw an imaginary line between
the gingival margin of the central incisor and the canine and the gingival margin of this pontic
should be one millimeter below this imaginary line if this excess tissue isn't removed the
pontic would look really small and you won't have the most aesthetic result the alternative is to
do a ridge lap design but these would be really difficult to clean for the patient which is also
not ideal when taking your impression ideally you should take both your working impression and the
opposing impression in light and medium bodied silicone you will rarely need to use retraction
cord pallately or lingually to expose the maximum area of enamel and when you're doing anterior
work or multiple units posteriorly then you should be using a face bow you can also use an intraoral
scanner and the benefit of this is that you can send the image to the lab and keep your
articulating paper marks present to demonstrate where the patient is occluding you want to send
the lab a set of instructions in the prescription and they are as follows please construct a
cantilevered rbb replacing the upper right three from the upper right four using nickel chromium
alloy full occlusal coverage with metal covering all occlusal mesial and pallatal surfaces minimum
thickness of the wing equal to 0.7 millimeters bridge will be cemented in high thick connectors
with a minimum height of three millimeters modified ridge lap pontic please sandblast fitting
surface pontic to have a light shim stock hold on icp pontic to have no contact in lateral excursive
mandibular movements and you also need to send them the shade that you want the pontic to be
now when you come into the appointment and you want to try in the bridge
you can do this using non-new journal temp bond and you can check the fit of the retainer the
occlusion and the aesthetics if any adjustments need to be made now is the time to make them
once you're happy with the try-in you want to bond it in and we need to consider three things
the resin bonded bridge retainer the tooth itself and the cement we'll use so starting with the rrb
retainer we want to sandblast the wing immediately before cementation with 50 microns of alumina
to increase the surface area and micro mechanical retention then you need to steam clean it to
remove any alumina or metal deposits or you could alternatively etch with phosphoric acid for 20
seconds and wash it off finally you need to apply a metal primer for bonding and make sure you don't
cure it on the tooth itself we need a rubber dam with floss ligatures for moisture control
then you use a polishing disc to clean any debris before sandblasting etching and rinsing with water
then you need to follow the bonding protocol of the cement you'd like to use as for the cement
itself you could use a dual cured resin cement like panavia or variolink but there are loads to
choose from once bonded in you want to check the occlusion clear excess cement teach the patient
how to clean under the bridge and between the retainer and the pontics then you should review
the patient and use an ultrasonic or bur to remove any more excess cement and make sure the dial is
working if they had orthodontic treatment you would provide new retainers once their teeth have
dialed in and ensure they have regular visits to ensure continued periodontal stability if needed
okay guys we hope you found that video useful and if you did we'd really appreciate it if you
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haven't done so already thank you guys for watching and we'll see you in the next video