intro to bridgework Flashcards
what are bridges for
- missing tooth or teeth
what are the reasons to treat missing teeth
- aesthetics
- function
- speech
- maintenance of dental health
how does treating missing teeth help function
- help eat and speak
how does treating missing teeth help speech
- tongue is involved in contacting teeth to make sounds
how doe treating missing teeth help maintain dental health
- if there is a space teeth can tilt or over erupt and can then expose root surface which is more susceptible to root caries and sensitivity
what are the tooth replacement options
- denture
- bridge
- implants
what is a bridge
- a prosthesis that replaces a missing tooth or teeth and is attached to one or more natural teeth
what is another term used for a bridge
- fixed partial denture
why can dentures be better than bridges
- they are better at replacing false gingiva to replicate lost soft tissue
- can still add a little on bridges but dentures better
what are the 2 main types of bridges
- adhesive which is most common
- conventional
what is an adhesive bridge
- held onto abutments by little metal wings on the palatal surface
what is a conventional bridge
- held on by crowns on the abutment teeth
what are the general indications for a bridge
- function and stability
- appearance
- speech
- psychological reasons
- systemic disease such as epilepsy
- co-operative patient
what are the psychological reasons for bridges
- some patients struggle with the idea of taking their teeth in and out and would rather something fitted
why are bridges good for epilepsy
- could inhale a denture during an epileptic fit but bridges are fitted
what are the local indications for a bridge
- big teeth
- heavily restored teeth
- good abutment angulations
- good occlusion
why are heavily restored teeth a good indication for a conventional bridge
- because they have already been restored so are already compromised
what are the general contraindications for a bridge
- uncooperative patient
- medical history - allergy to materials
- poor OH
- high caries/perio
- large pulps in young patients
why are large pulps a contraindication for bridGES
because tooth could go non-vital if start trimming it down and get close to pulp
what are the local contraindications for bridges
- high chance of further tooth loss
- prognosis of abutment poor
- length of span too big
- ridge form/tissue loss
- tilting rotation of teeth
- degree of restoration
- good periapical status is required
- perio needs to be stable
why are big spans a contraindication
- will flex more as patient bites down and it will fail
what does abutment mean
- tooth that serves as an attachment for a bridge
what is a pontic
- artificial tooth suspended form abutment
what is a retainer
- extracoronal pr intracoronal restorations connected to pontic and cemented to prepared abutment teeth
- metal wing or crown
what is a connector
- connects pontic to retainer
what is the edentulous span
- space from missing teeth
what is the saddle
- space where the pontic sits
what is a pier
- abutment tooth that stands between and is supporting 2 pontics, each with another abutment on the other side
what is a unit
- either a retainer or pontic
- i.e. - bridge with 2 retainer and 1 pontic = 3 unit bridge
what is a fixed-fixed bridge
- retainer at each end and a pontic in the middle
- can be adhesive or conventional
what is a cantilever bridge
- retainer only on one side of the pontic
- can be adhesive or cantilever
what are other names for an adhesive bridge
- resin bonded
- resin retained
- minimal prep
- maryland
- resin bonded fixed partial denture
what material is most commonly used for metal wings
- CoCr
- some evidence showing ceramic is good but not much yet
what are the advantages of adhesive bridges
- minimal or no prep
- no anaesthetic
- less costly, less surgery time
- used as a provisional - if getting implants
- less destructive than alternatives
what are the disadvantages of adhesive bridges
- good clinical technique needed = needs to be bone dry
- metal shine through tooth if overextended incisally
- chipping porcelain
- can debunk
- occlusal interference
- no trial period possible
why should you check dynamic occlusion as well as static
- to make sure when teeth are moving that the bridge is not going to be broken off
what are the indications for adhesive bridge
- young teeth as less destructive on them
- good enamel quality
- large abutment surface area
- minimal occlusal load
- good for single tooth replacement
- can simplify PD design
what are the contraindications for adhesive bridge
- insufficient/poor enamel
- long spans not possible
- excess soft/hard tissue lost
- heavy occlusal force as more chance to fail
- poorly aligned, tilted or spaced teeth
- contact sports = need to make sure wear a mouthguard
what important to establish in history
- any parafunctional habits
what is a direct resin bonded bridge
- good in emergency situation, done at chariside
- use pt’s own tooth that has fallen out, or can use acrylic denture tooth, or polycarbonate crown or cellulose matrix filled with composite
- cut root off crown and remove pulp and seal over pulp
- use composite to hold the tooth onto the two abutments teeth
- doesn’t look great but works as a temporary
what is an indirect resin bonded bridge
- made in the lab
- take impressions and send to lab to make
- need big palatal/lingual coverage
- can have no prep/minimal prep/heavy prep
how far supragingivally should bridge be kept
- ideally 0.5mm
what adhesive bridges are generally used anteriorly
- cantilever
what adhesive bridges are generally used posteriorly
- fixed-fixed
why use cantilever anteriorly
- because of divergent guidance paths
- the occlusal forces are directed down each tooth in a different way which means when the bridge is used it will move in different directions and break
if there is previous restorations in abutment teeth what do you do with them
- composite is ok to stay, but could roughen it with a slow speed for better retention, or could replace
- if amalgam want to take out and replace
what prep needs done for adhesive bridges
- 180 degree wrap around
- need rest seats occlusally for post, and on cingulum for anteriors
- can do proximal grooves but not needed
- chamfer line 0.5mm from gingival margin
- prep should stay in enamel
what is the anterior minimal prep
- occlusal contact reduction
- cingulum undercut removal
- chamfer
what is the anterior heavy prep
- 0.5mm palatal reduction
- cingulum rest
- +/- proximal grooves
- chamfer
why will the bite feel high to the patient
- because reduction is only 05.mm but wing is 0.7mm so there is a 0.2mm discrepancy
- take 10-12 days to get used to
what is the posterior prep
- occlusal rests
- 180 degree chamfer wrap-around
- +/- proximal grooves
how can missing tooth space be temporised while waiting for bridge
- RPD
- Essex retainer with missing tooth filled in
- if prep only in enamel don’t really need temporary
- if into dentine ca cover with DBA and give sensitive toothpaste
how is the retention of the metal retainer improved
- sandblasted
what is sandblastign
- micro mechanical retention
- creates small indentations on the fitting surface where the cement will then ‘lock’ in
- use aluminium oxide 50 microns
- done in the lab
what cement is often used to cement in
- Panavia
- dual curing cement
how is retainer treated before fitting
- try in for fit and aesthetics
- chair side micro-etching if not been done in lab
- clean retainer = ultrasonic bath, ethanol to degrease
- apple cement just prior to placement
what can you ask lab to provide to make trying in fit of bridge easier
- ask for them to place locating cleats on the incised surface that you can hold to try in
- these then break off
how are the teeth treated before fitting
- isolate with dam
- etch = 37% orthophosphoric acid
- wash and dry
- apply primer (A and B mixed) for 30 seconds then air dry for 2 seconds = don’t need to cure this primer
after fitting bridge what is placed around cement margins
- O2 inhibitor (Oxyguard II) is placed around cement margins for 3 minutes then washed off
what do you need to do after cementation
- check occlusion = make sure pontic doesn’t have excessive occlusal contact
- demonstrate how to clean around and underneath the bridge
what is the survival rate of adhesive bridges after 5 years
- 80%
what is the survival rate of adhesive bridges after 10 years
- 80%
if adhesive bridges are going to fail when is it most likely
- first 2 years
