To help serve you better, we have put together a checklist of the items needed to complete a cosmetic or large restorative case.
REDUCTION AND SMOOTH PREPS: Depth
cutting burs and clearance tabs are helpful
but you must think anatomically for realistic
contour and esthetic shades! For PFM's it's
important that you have 2mm occlusal reduction
and at least 1.5 mm on the facial for porcelain
esthetics. Smooth your preps to reduce sharp
angles and irregularities (hat cannot be dequately
reproduced in stone.
2. IDEALIZE ADJACENT PROXIMAL AMD OPPOSING1 OCCLUSAL CONTACTS BEFORE IMPRESSING: Too many cases arc compromised by a failure to address these irregular surfaces. By minimal recontouring of adjacent proximals you can often dramatically improve results. Occlusal adjustments (equilibration) will help lab techs properly mount a case and minimize occlusal adjustments on crowns at delivery.
3. CLEAN THE
PREP ADEQUATELY AND DRY IT: If you
used a flowable composite or other resin base,
build-up, or temporary material on the prep,
there is a dispersion layer on the prep surface
that inhibits PVS impression materials. Thoroughly
wash and pumice preps before impressioning
4. IMPRESSION TRAYS: Restrict quadrant tray use to 1 or 2 posterior units when there is a posterior stop (tray recommended from Clinician's Choice Quad Tray 1-800-265-3444.) Use full arch trays when no posterior stops, restoring canines, or 3 teeth or more. Never let teeth touch the tray: distortion, rebound, and powdery inaccurate cusp tips are all the result. Don't use triple trays for inlays or onlays. When margins meet mesh, we all lose.
5. FLEXIBLE TRAYS: Flexible trays will flex buccal-lingually to accommodate more bulk of material and then rebound. Die is small, tooth is big. Crown doesn't fit, margin is open and occlusion is high.
6. DON'T RELINE IMPRESSIONS:There is simply no way to "see" that an impression is completely reseated in exactly the same position or to the same degree of closure. Your relined margin might look great but it's relation to the occlusal surface of adjacent teeth and to the prep itself is often inaccurate and undetectable until seating failure.
7. BITE REGISTRATION: Use a rigid bite registration material like Blue Mouse or similar rigid material. Please don't use clear bite or other rubber like materials that have a memory or offer resistance on closing. When doing one or two teeth, take a bite over the preps only and make sure the contra-lateral occlusion is unaltered while taking the bite.
8. USE MORE WASH: Nothing improves margins, occlusion, fit and contacts more than using more wash (light body). Putty, medium or heavy body tray materials simply don't have the detail you need to get accurate dies. Contacts, opposing teeth and prep detail are all enhanced by more wash. Again, the result is fewer adjustments.
9. FITTING CROWNS: If a crown doesn't go to place immediately, check the die. Impression materials are far superior to gypsum when it comes to reproducing sharp detail on incisal or occlusal edges, axial line angles and other areas. Careful inspection of the die may reveal an area where detail is not accurate to the prep. Brushing these areas with a fine diamond is quicker and easier than most fit-checker silicones, markers, etc.
10. CEMENTATION GETS EASIER: The newest cement from 3M, RelyX Unicem, appears to have won the hearts and minds of dentists all over the country. For ease of use, clean up, and reduced post-op sensitivity, nothing seems to beat this new material by all accounts of Keller clients.