High and Dry Margins-Crownlay with e.max HT
This isn't a novel post but for some of the new CEREC users, I thought I would share some bread and butter dentistry. I would rarely do crownlays during the BC (Before CEREC) days. As we all know the biggest challenge was provisionalization and you as the clinician had to be knowledgeable enough about materials to explain to the lab technician about material selection, color and translucency so you could get the results you desired.
Now with CEREC, there are a number of different materials at our disposal and no worries about provisionals. For this case, I had plenty of enamel to bond to and enough clearance so I could have used just about anything in this case. Typically my go-to for crownlays is IPS e.max HT (high translucency). I've used MT with success but I find blending the margins is a bit easier with HT.
Another thing I really try to focus on with these cases is smooth flowing margins. Unlike the days of gold inlays and onlays where sharp internal line angles and boxes were the norm, resistance and retention form are not my primary concern. With proper bonding, these do not come off.
For this case, I intentionally choose A2 HT because the cusp tips of the premolars where brighter. I selectively etched the enamel with 35% phosphoric acid, scrubbed the tooth with Adhese Universal for 20 seconds and bonded with Ivoclar Vivadent Variolink Esthetic Warm Plus.
Nothing earth shattering, but these are the types of cases where efficiency and predicatability are paramount for us each day.
Pretty slick work there Dan. Nice bevel on the facial to get that blending effect. What are your thoughts on the try in the pre crystalized phase and potential for chipping at that margin? I'm very rarely trying any emax in anymore. Just curious why you did in this case.
Tom
Good question Tom.
I definitely don’t check occlusion in the blue phase. Had a few chipping at the margins and a few was too much for me. As far as chipping at try in, that hasn’t been a big issue for me. I will say I bulk up my margin thickness to 100 since I tend to prep fairly conservatively for my chamfer margins (~0.8mm). I will thin my margins out post try in. No problems with chipping at this point.
Dan
Nice Dan... we always try in at blue state as well... not to be confused with checking the bite in the blue phase....everyday beautiful!
Mark
Looks beautiful Dan. Do you find that you need to put an oxygen inhibition gel on the margin while curing to prevent future staining of the buccal margin or is etching the enamel enough?
Yes Dan, I use Ivoclar’s liquid strip but as you know, any brand of glycerine type gel that is approved for intraoral use is appropriate.
I know Skramy has posted videos of him bonding and wiping all the extra away with a rubber tip and flossing. Then initial light cure and placing a gel for the oxygen inhibition layer and then he’s done. I’m not that good so I’m always dressing my margins a bit with finishing burs and 3M soflex discs after removing the majority of the excess cement. Then I repolish those areas. Since I do that 99% of the time, the liquid strip may be a mute point but I definitely use it.
Before I knew any better did have a couple of cases on crowns that supragingival margins that I didn’t finish down and didn’t cover with a glycerine type of gel and did get some staining.
That has been my go-to restoration with Cerec for the past almost 20 yrs. IMHO, the onlay restoration is the best reason to get into Cerec.
In these cases, I️ only stain and glaze the occlusal to accentuate anatomy. I️ don’t place stain on the facial or lingual margins.
