Did the composite base cause this e.max crown to fail?
This IPS e.max CAD crown was placed October 4, 2016. Dutiful little dentist that I am, I based out a deep irregularity in the preparation, which had contained amalgam, with composite. The composite material was Kerr's Vertise Flow. Here is a photo of the fractured crown, removed with the Lightwalker crown debonding protocol. As can be seen in the photograph, the cement base came out with the crown. RelyX Ultimate can be seen adhering to the intaglio of the crown. Could the base somehow have contributed to this fracture? Would it have been better to skip applying a composite resin base to the preparation and imaging the rough preparation? Thoughts anyone?
Chuck, when I place a core (not block out material), I use a "hard" composite. Best I ever used, Z 100. The amount of flow here might not have held up well support wise which may have led to the this result.
The crown is 1.65 mm thick on the occlusal, >1.0 mm thick in the mid axial area, approx. .6 mm thick at the margin. This is the second e.max fracture I have had in my 11 CEREC years. Here is a photo of the replacement. It is a Katana STML Zirconia. I do not have Katana STML A 3.5 in stock. Per Skramy's recommendation, the shade of the adjacent premolar is A3.5, so I did polish only, A3. As can be seen, this polish only does not appear darker than it's indicated shade. it is pretty much an A3,. The flash exaggerates the color discrepancy. It looks acceptable in the mouth. But it would have been better if I had used A3.5.
Mark,
This was not a core, it was block out, but it is in a spot which offers some support. I appreciate your input. I like Vertise Flow for block out because it is self-etching, therefore fast and easy. I suspect I pushed the envelope too much in this case, as you suggest.
Based on the composite block out being in the prep, I would say the bond of the flowable to the tooth failed. This, combined with the relatively flexible nature of most flowable composites probably allowed for too much flexure with resultant fracture of the overlying emax.
Or, it was just bad luck.
Charles, Vertise Flow is „okay“ for small defect, but nothing for anything that has to withstand any stress to the bond. I find it very much doubtful that the achieved bond strength with Vertise is similar to any pure self etching bond, just for chemistry reasons ( 10% glass particles in Scotchbond Universal compared to 70%+ for Vertise? ). Many users do not agitate the flow enough by the way, they mostly apply and leave it sitting for a few seconds before curing. You used RelyX Ultimate, so also Scotchbond Universal. Scotchbond Universal is quite acidic, and could undermine the bond layer of the weaker vertise.
Here you go Gregory. Not much direct contact. I'm pretty sure this patient has sleep apnea and struggles to breathe when he is asleep. He is quite overweight. Gregor, your dental materials lesson has convinced me. The problem was likely the Vertise Flow block-out.
TK, I have had nothing but fractures with Celtra Duo, and I have polished and fired every one I have placed. IMO, Celtra Duo is the worst material we have--worse than Enamic by far. You can have all my inventory. Dentsply Sirona should be ashamed.
Charles, have you forgotten to place a smiley after your comment, or was it not meant to be ironic with the „material lesson“?
Did it fracture off? or just crack?
How do we know what was or wasn't debonded with the laser vs. before?
The small piece was fractured and debonded, but it was wedged in place. The large portion was still bonded. So, as I think about it, the crown was not fractured through the block out.
Two e.max fractures in 11 years? I’d say you’re doing something right and would chalk this one up as a fluke.
Your concern about the one failure among thousands of success shows your commitment to excellence as well as the overall spirit of this community - always questioning, learning, and sharing experiences with everyone else.
Perhaps a flowable isn’t as ideal for blockout as a more filled composite but I wonder how much this matters in practice. Does anyone know of any studies on this, specifically for bonded ceramics?
It could have been production related, like the pin was in physical contact with the emax through the object fix,during crystallization? That could create weakness in ceramic.
