provisional extra-coronal restorations Flashcards
what are the clinical stages of provisional extra coronal restorations
- Preparation
- Temporisation
- Impressions and registration
- Cementation
- Success of each stage is dependent on success of preceding stage
why is tooth preparation not ideal
- compromises aesthetics in smile line
- occlusion reduction in function
- destabilises occlusion
what should provisional restorations do
- have a good marginal fit
- be well contoured
- cleansable and maintained by patient
what happens if we have a poorly fitting contoured provisona
- patient unable to clean = caries, periodontal disease
- poor moisture control
- gingival overgrowth
what must provisionals do
- establish and/or maintain dental aesthetics, mimicking either the original tooth or a definitive restoration
- prevent sensitivty
- allow ‘optimum home care’
- prevent micro leakage
what are some additional uses of provisional restorations
- isolation for RCT
- matrix for core build-up
what are desirable characteristics of provisional materials
- non-irritant
- low temperature rise during setting
- dimensionally stable
- adequate working time
- adequate setting time
- adequate strength and wear resistance
- good aesthetics
what are the different types of provisional restorations
- Custom formed
* Preformed
which type of provisional restorations are preferred
- customer formed
- can be technically demanding however
- fits better and looks better
what materials are used for custom provisional restorations
- typically made out of composite
- chemically cured bis-acrylic resin
why is composite good to use for provisionals
- customisable = can add to it or take away
- easy to adjust
what is a svensen gauge
- pincers to clamo over restoration and needle slide up the ruler to show how thick it is
- can use temporary restoration to check how much tooth you have removed
what type of impression do we take for temporary restorations
- sectional impression
- don’t need full arch
what materials are used for an impression
- addition cured silicone putty = ‘President’
- alginate
- softened modelling wax
why is president a good impression
- can be disinfected
- can be reused
- resistant to tearing
- doesn’t shrink of expand over time
- mainly used
what are the properties of softened modelling wax
- easy to adjust and smooth
- cheap
- unsuitable for deep undercuts
- distorts
- cannot be reused
- easy to use
how are custom made vacuum formed stents made
- sectional impression
- prepare tooth for chosen restoration
- syringe bi-acrylic composite resin into bracket table or mixing pad
- syringe material into sectional impression of tooth that has been prepared
- relocate impression in the mouth
- remove completely
- remove flash and ledges
- confirm tooth preparation
- check marginal fit and occlusion in situ
- check aesthetics
- cement provisional restoration with temporary luting cement
how full do you fill the impression with Protemp
- 3/4 full
what pressure is used to seat temporary restoration
- finger pressure
when may we need to reestablish occlusion and aesthetics
- loss of original tooth form = from wear
- for guidance
what type of guidance is preferable
- canine
how do we form guidance
- produce on crowns
- diagnostic wax-up = take upper and lower impressions of patient with toothier
- articulated study models = on articulators
- Facebow registration required if changing occlusion
what do we do once guidance and aesthetics are satisfactory
- lab duplicates waxed-up cast
- construct vacuum formed stent
- prepare teeth in next visit
- patient trial
what articulator is commonly used
- semi-adjustable articulator
how do we record the lateral and protrusive movement
- place unset acrylic on the incisal table of the articulator
- reproduce the lateral and protrusive movements on it
what do we do if it is a high aesthetic demand case
- alter provisional restorations = minor changes at chair side
- extensive changes = replace provisional restoration
how do we establish gingival contours
- use provisional restorations to achieve satisfactory emergence profile for definite restorations
- when providing implants can use provisional restoration to hold gingiva around tooth
what is the emergence profile
- shape that the tooth takes after it comes off the implant as it comes out of gingival
what happens if the emergence profile is flat
- the gingival would collapse in the way and wouldn’t look as aesthetic
what happens if the emergence profile mimics the natural tooth
- want to make sure provisional pushes the gingival out a little bit to mimic contour of gingival around a natural tooth
what are the two variations of preformed provisional crowns
- tooth coloured = polycarbonate
- metal = aluminium, stainless steel
why do we need a large bank of different provisional shapes and sizes of preformed crowns
- because there is so much variation in patients
what are the problems with preformed provisional crowns
- unlikely to fit accurately
- large bank of crowns needed = expensive
when can preformed provisional crowns be used
- good for situation where no impression is taken prior to tooth preparation or damage
- good for when we are put on the spot and need a provisional restoration = trauma cases
what are polycarbonate crowns used for
- mainly for anteriors and premolars
what is the method for placing preformed provisional crowns
• 1 - Select shell slightly larger than preparation • 2 - Trim back until - Correct preparation dimension - Seats fully over tooth preparation - Not bedding into gingivae - Adjust to get some degree of fit around margins • 3 - Fill shell • Trim or Protemp • 4 - Seat over tooth • 5 - Allow polymerisation • 6 - Remove • 7 - Check fit • 8 - Trim/Tidy if necessary • 9 - Cement
how are clear plastic crowns placed
- Select and trim until fit
- Pierce hole at cusp tip/canine tip/incisal angle
- Fill with bis-acrylic composite resin
- Seat over tooth
- Allow setting
- Remove from tooth
- Remove plastic crown form
- Check margins and occlusion
- Cement with temporary cement
what are metal preformed crowns used for
- posterior teeth
what are some problems with metal preformed crowns
- cause trauma to soft tissues
- difficult to adjust
- very rarely do in adult dental setting
how do you remove an old crown
- with a WAMkey
- safe relax/Anthrogyr
- sliding hammer
how does a safe relax/anthrogyr work
- automated version of sliding hammer
- handpick to connect to handpiece
- pull handpiece up to hear it clock and engage
- press foot pedal to hear steady tapping
- little wires go under Pontic of bridges to get them off as well
how does a sliding hammer work
- metal rod with weight sliding up and down on it
- different heads for it
- put hook round margin of crown and slide weight up crown and it bashes against top of crown
- taps of crown in occlusal direction
what is good about preformed malleable composite crowns
- they are soft
- easy to mould to tooth prep
- shaped like a tooth but not set yet so can mould it
how are preformed malleable composite crowns placed
• Moulded over tooth to desired shape • Partially light cured • 2-3 secs - If any longer than this then difficult to remove • Otherwise – difficult to remove • Remove then completely cure outside of mouth • Check fit • Adjust if necessary • Cement
what is a spot bonded temporary veneer
- Divide tooth into 9 square and in middle put little bit of bond and basically add composite bit by bit onto labial surface of tooth to build up a veneer then cure it
- Last a few weeks
- Not as bonded as usual, but don’t want that as want to just be able to place excavator under it and flick it off
what are the properties and what are the stages for indirect provisional restorations
- Lab made (usually acrylic)
- Low shrinkage intra-orally
- More accurate
- High strength
- Time and cost consuming
- Used long-term
- Examples of used materials: Composite, Acrylic, Metal
- Lab will make something more accurate than you would chairside
- Acrylic higher strength than soft composite material s
- Problems
- Because you now added extra layer of complexity to treatment plan so more visits and lab time required so costs more time and money
what can be used as provisional replacement of missing teeth
- conventional bridgework temporisation
- acrylic removable partial denture
- Essix retianer with Pontic
what is a conventional bridgework temporisation
- similar to custom-formed provisional crowns
- diagnostic wax-up of replacement tooth
what is a conventional bridge
- two crowns with a retainer
what can you do if you don’t want to use a conventional bridge
put two temporary crowns on abutment teeth and fill edentulous space with temporary denture or essex retainer with pontic which is basically a mouthguard
what can happen if you leave edentulous spaces
- teeth can tilt into that space
- not ideal
how are resin bonded bridges made
- not a lot of prep
- provide a little denture in the space as there is nothing for a provisional bridge to hold onto
- or a Essix retainer
what is the best method for provisional replacement of missing teeth if doing implant work
- probably best to use little denture or Essix retainer
why do patients need to be cautious with floss with provisional restorations
- may pull it out
- need to pull floss out in a forward direction rather then pulling it down as more likely to dislodge provisional restoration
what happens if patient doesnt maintain good OH
- gingival inflammation
why is gingival inflammation a problem for definitive restorations
- bleeding
- poor moisture control for definitive impressions
- inadequate cement lute placement
