Some notes on temporary crowns and veneers

Some tips from Lincoln's course

• The temporary stage is essential for diagnosis of aesthetics, phonetics and function as you can adjust the occlusion,  add material, change the aesthetics without damaging the final crowns or glaze. Avoid skipping the diagnostic phase in multi unit cases.
• When adjusting anterior aesthetics "make a box" by first adjusting the incidal edges then interproximals. This will make a block of material that you can then shape. Aim to "remove any material that makes it not look like a tooth. Polish the embrasures and then labial surfaces and then add secondary anatomy.
• When using bisacryl temporary material, take out the stent after the suggested time and leave on the bench for 1 minute to allow further set then slowly tease out. The bisacryl will still be slightly soft and prone to deformation as soon as it is removed. In very critical, full arch cases you might need to get your assistant to open the flanges of the stent to allow you to pull the temporaries out. 
• After the temporary has been removed from the stents put it back on the tooth and take on and off. This is to account for shrinkage of the material. The material is still soft so the intaglio surface will abrade slightly. There can be cases where it fits immediately after taking out of the stent but after leaving it on the bench it doesn't fit after significant adjustment due to shrinkage.
• If there is a rough appearance of the temporaries it is because the stent was removed before the plasticiser has set. If you notice this then rub the surface with your gloved finger before the plasticiser sets to smoothen the surface
• When making adjacent acryllic temps, place the already made temporaries on the tooth or the new material will flow into their area and you wont be able to fit both sets in. Place teflon on the existing temps as a separator or they will bond together and if they have a separate path of draw they will be locked into place or if you remove the putty key the setting acryllic may tear. 
• When making segmental temporaries, place apical pressure on the teeth with temporaries on them already or your will overcompress the putty key over the preps and make the temporaries too thin. This is often the cause of thin temporaries despite sufficient tooth reduction in crowns and veneers. If there is show through in your temporary then recheck the occlusal reduction. If it is sufficient then ensure that you are placing apical pressure on unprepared teeth or temporaries that are in place rather than over the preparation. Your putty key needs to cover sufficient hard tissue to have these positive spots in place to allow compression
• A crown remover can be used to remove the temporary crowns. Use it on a robust margin otherwise the temporary is likely to chip. Do little taps all around the crown. 
• Artery forceps can be used to remove temporary crowns as well. slightly squeezing the crown can deform it and break the cement seal. If you squeeze too hard with the artery forceps when removing the temp it can fracture when it comes off and the crown is unsupported.
• When making veneer temporaries if there are black triangles and you aren't aiming to close them you need to fill these spaces with teflon cords when inserting the putty stent otherwise the temporary material will get caught in the undercuts and tear on removal or get locked in Flowable resin can't be used as the bisacryl will bond to this. During impressions in these cases,you can block out the lingual surface of these triangles with flowable composite to avoid locking in of the imperssion material and tearing on removal. If the tray gets stuck on it may need to be sectioned off
• Avoid shrink wrap temporaries where you leave the bisacryl to fully set and shrink onto the teeth as you can't easily contour the margins and it tends to cause poor gingival health.
• Well fitting temporary veneers can be bonded into place.Prime the intaglio surface of the temporary veneers with SE bond. Spot etch the tooth and slather bond only (not self etching primer) on the tooth. Apply the veneers and cure through the veneers. These will likely need to be sectioned off.
• When taking impressions of temporaries that you ideally want to stay on, pull one side of the tray down first resulting in off axis loading on the temps. PVS is ideal to provide crisp margins to the technicians to allow measurement of crown heights to transfer to the final crowns. However, when you really want the temporaries to stay on after this impression i.e if you are worried that recementing them will result in changing the bite you have worked hard for, you can use alginate for the impression.
• most important part of preop impression of temps to gain a replica of the incisogingival dimension. it is hard to capture this crisply in alginate. Temps need to be good. if there is a poorly fitting margin the it is difficult to determine the dimension.