We had used China Zr block before but we stop using it.. But we are using the 98mm round block... Reason of stop using:
1. Not very fit after sintering, esp for long span bridge (we do lotss of long span bridge). Of course u can do the grind etc, but i think it takes too much time... so if u count on labour cost it will be not very profitable...
2. Mostly China blocks are high opacity, which dentist here hate so much...
3. If u buy in bulk quantity, i think VITA had good price only a bit more expensive than China, but so much better fit, we rarely grind or do any seating at all, even at long span bridge..
4. I had 1 case single crown that breaks in 1 month. Well... only 1 case out of so many case we had done with China Zr, but it makes me doubt the quality...