36 JULY 2017 // dentaltown.com

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1 36 JULY 2017 // dentaltown.com

2 Crowns Fit for Royalty A Townie needs tips on how to improve her success rate Turn the page to read an excerpt from one of Dentaltown s busiest message boards. dentaltown.com \\ JULY

3 message board Help! None of My Crowns Are Fitting! So. Many. Remakes. A dentist s efforts at seating crowns are failing too often for her liking. Can her fellow Townies identify the cause(s)? Post: 1 of 217 Triad Member Since: 06/18/03 Post: 2 of 217 almunk Member Since: 12/17/05 Post: 3 of 217 Post: 4 of 217 I am going crazy lately! About one out of every five crowns is a remake for me. I m not sure if my standards for seating are unrealistic, the crowns lab sucks, my preps suck or my impression material sucks. I bought a practice in July and started using the impression material and lab the previous dentist was using. After having many, many issues, I switched to a better lab but it s way too expensive, considering I take lots of insurances. I had more success with the expensive lab with about one out of 10 crowns for remake. (I think that s still high.) I use Affinis impression material and I take pride in how awesome my impressions are. The expensive lab even complimented me on how great my impressions and preps are. (Maybe they were just blowing smoke, thoug.) When I seat a crown, I check the contacts, margins, then occlusion, then I take an X-ray if all is good. If it doesn t seat properly, I adjust contacts if needed, check for gums over the prep (happens a lot), tight contacts, smooth pointy spots on the prep and adjust the inside of crown after checking with fit checker. What am I missing? Why does it take so long to seat a crown when I can seat them? I talked to the owner of the lab and he didn t have anything major to point out about my impression or prep, just kept shrugging and saying maybe this or maybe that (none of which could possibly be the lab s fault). I sat down with my friend who is a dentist with all my model work and asked her to critique me, and she said my preps looked good and she doesn t know what to tell me as to why this is happening. Does anyone have any suggestions on labs to use in or near Florida? Any suggestions on how to seat crowns more efficiently? Should I switch from PFM to zirconia? Does anyone use Affinis impression material with success? (From what I see, it takes good impressions,) Help! n What problems are you having? Open margin, overhang, occlusion? n Find another dentist to evaluate your whole procedure. Have the lab pour a solid model as well. It will be hard for DT to pin down what the problem is. Let us know if you make any progress. If you just can t find anyone to mentor you, you ll need a good camera and a lot of photos to get any online help. n Open margins/crown seats in more than one spot or rotates/won t fit down onto the prep by a lot, even if I shave off all the contacts. n Continued on p JULY 2017 // dentaltown.com

4 message board Continued from p. 38 Nicknack Member Since: 02/25/13 Post: 6 of 217 Post: 8 of 217 Tom Mitchell Member Since: 02/16/04 Post: 15 of 217 Brett Mansfield Member Since: 08/19/05 Post: 18 of 217 lefty50 Member Since: 08/17/02 Post: 25 of 217 Velogeek Member Since: 04/15/10 Post: 27 of 217 tricuspid Member Since: 08/09/07 Post: 30 of 217 Are you relining impressions i.e., taking a putty and then reseating it with wash? They always look perfect but rarely are. n Sometimes I reline with light body if I want the margins to be more clear. I don t do it that often, though. I had a mentor dentist that took all his impressions that way. He didn t seem to have problems. I am definitely going to never do that again if it could be one of the culprits. Thanks! n Are your margins supra- or equal gingival? Are your temps supporting the tissue adequately? Are the prox contacts on the temps closed or open? Best of luck. n So many possibilities Can you take some pics of some preps and impressions? Who makes the temp and cements it? What cement? Is it all types of crowns, or crowns of a particular material that are the issue? BTW, personally, I would not recommend relining impressions. The concern is that the previously set material will flex away from the tooth slightly when relined, then spring back once removed. Ultimately, the die will be dimensionally smaller than the actual tooth and the crown would not seat because it was binding everywhere. There are some that have good success with the H&H technique, but they use specific materials and a specific technique. n I sat down with my friend who is a dentist with all my model work and asked her to critique me and she said my preps looked good and she doesn t know what to tell me as to why this is happening. Is your friend having good success with her crown preparation and seating techniques? If so, why not watch her do a few, and duplicate her technique? n OK, let s stop for a moment and discuss this. Cast only and milled indirect restorations fit fine. Metal ceramics do not. Question 1: Are they using noble metal or base metal? Question 2: Are you willing to do a metal try-in to identify if the problem is with what they are casting or if it s occurring after the ceramic application? n Another thing to consider: Make sure that you are leaving the impression material in the mouth for long enough. I used Imprint 4 for a very brief but traumatic period. It was during a particularly cold winter here; Imprint 4 is apparently very sensitive to temperature, and coming up to body temperature is what allows it to set quickly. All my Imprint 4 impressions during this time were looking great, but the crowns were coming back awful. Apparently what was happening was that the material was continuing to shrink after I removed it from the mouth. The margins still looked good to the eye in the impression, but nothing would fit when I got the crowns back. I finally got answers from 3M, who admitted that Imprint 4 required extra set time if it was cold at all. I discontinued using Imprint 4 because of the headaches and redos. I now use Continued on p JULY 2017 // dentaltown.com

5 message board Continued from p. 40 Exafast NDS. I love it, but I give it an extra 30 seconds over what the manufacturer recommends so that I never have another problem like I had with the Imprint 4. n Jamar M Jackson Member Since: 04/03/05 Post: 33 of 217 Post: 35 of 217 llmgwc Member Since: 10/23/10 Post: 44 of 217 Velogeek Member Since: 04/15/10 Post: 45 of 217 Eeznogood Member Since: 02/23/06 Post: 59 of 217 Uwe Mohr MDT Member Since: 01/10/05 Post: 61 of 217 Were your crowns fitting well, and then all of a sudden started not fitting? Have you changed anything in your technique or materials? The answer to these questions will help to know where to start looking for the problem. n I did a residency before I bought the practice that was practically public health, so I didn t do a lot of crowns. Before that, I worked in corporate and they sent our crowns to China for like a lab fee of like $20 a crown. I had a little more success then. n Had the same exact problems, used H&H technique (I guess not sure what that even means, lol). Did two things: 1. Switched to Glidewell to see if that helped. It did. So then 2. Asked my regular lab to increase die spacer (it uses digital), and that has helped a ton. Ask them to increase the spacer even more if it has helped but isn t perfect yet. n Doesn t this concern you? Because it should. n I believe that Velogeek meant to say that if there are inaccuracies in the impression or the prep or the fabrication process, it would be best to figure them out, rather than compensate by bumping the die spacer. The die spacer should not be too big, because cement is only strong in compression if it is thin enough. Once it gets too large, it breaks down easily, and while this larger space might help the crown seat fully, more care in all the steps might allow it to seat fully without this potentially dangerous cheat. n There are two things that worry me here: 1. Impression technique (and you have been given some excellent advice). IMHO Impregum/ Permadyne and Garant produce by far the best results for me. 2. Fit. Zirconia and full metal fits, PFM doesn t. That seems to be a lab issue or PFM procedures. Adding additional die spacer (digital or manual) does not solve the issue; all it does is make your crowns fit loose eventually to the point they will rock/rotate. You need to eliminate the variables to see where the issue is. My suggestions: The obvious one: Your good lab with the higher prices does not seem to have that issue. Bite the bullet, pay the higher fee. Your loss of chair time and all the remakes cost you way more than the difference in lab fee. Option 2: Try another lab. If the issue is the same, it is you technique, tray, etc. But back to the fit: PFM technique is inherent to some errors. On the lab side, what you describe is porcelain on the intaglio of the crown not removed/sandblasted. 100% of PFM crowns have porcelain on the intaglio due to the manufacturing process. It needs to be removed at each step before going to the next step. Immediate fix: Have the lab pour a separate, untrimmed single die for you. Make sure to 4/12/ JULY 2017 // dentaltown.com

6 remind them that the inside of the crown has to be sandblasted. Then, when the next crown does not fit, trim the margins on the untrimmed die and see if the bad fit is the same. (It will probably be worse.) Good luck! n 4/12/2017 Time the impression material every time. Three minutes is forever if you time it. You need to check every temp before it s seated. With Pro Temp you can add cheap flowable if you need it. You are quality control for your assistant, it s a job; for you, it s that crown you will be looking at every six months. n Reading this thread, I think that I would sum up some of the many good suggestions as follows: Don t ever reline a C&B impression. Be aware of the working time of your impression material, and time the impression for the correct setting time in the mouth. Don t use flexible plastic triple trays; rather, use low-wall metal ones. Be sure that your temps fit the margins of your preps so you don t have gingival overgrowth in the interim. Be watchful for undercuts and sharp edges on your preps. Go for the correct taper, with no sharp angles that would create a thin fin of dental stone and fracture off the die, resulting in a die that is that much smaller than your actual tooth. Let us know if you solve your problems. n 4/12/2017 4/15/2017 IMHO Member Since: 11/12/06 Post: 75 of 217 drillher Member Since: 04/22/02 Post: 109 of 217 Share your suggestions for fitting crowns! Search: Crown Remake Help Do you have ideas that might help this Townie master her crown technique? Go to dentaltown.com and search the message boards for crown remake help this conversation will be the top result. FREE FACTS, circle 2 on card dentaltown.com \\ JULY