Thursday, February 24, 2011

Taking the time to do it right

Even after all these years I'm still surprised by the number of people who can never find the 2-3 hours to practice and learn, but always make time to spend 5-10 hours to correct the mistakes that would have been avoided... had they practiced and learned. This is true for CEREC as well as most other learned skills (e.g., placing implants, photography, golf, heart surgery).

My recommendation: if you're having trouble with something, practice first. If it's CEREC, ask me and I'll give you some simple homework. Or look on CADStar.org or cerecdoctors.com. A few minutes of practices goes a long way.

That's why we don't teach swimming in the ocean first....

Friday, February 4, 2011

Parameters

Some of you have been asking about your parameters or just changing them to random numbers. Here’s what they mean and what I recommend for settings:

Under Settings (top menu bar), click Parameters, then...(all numbers are in microns)

CONTACT STRENGTH is how heavy you want your initial interproximal contact proposal. 25 is just green, 50 is a spot of yellow, 75 is half yellow-half green, 100 is a spot of red, 125 is way too much. Start at +75.

OCCLUSAL STRENGTH is the strength of your occlusal contact. This tends to be too heavy by default. Start at -150. If they are still coming out high, lower to -200 or even -250.

OCCLUSAL OFFSET takes your restoration out of occlusion. It’s naturally 100 microns too high, so -100 is even. Start at -150. Take to -200 if you’re consistently high.

MARGIN THICKNESS gives extra around your margin to avoid submargination. I put everybody at 100.

OCCLUSAL THICKNESS is your minimal occlusal thickness, below which you will see the light blue “you’re too thin” warning. Set to 1000 (1.0mm) if you’re using emax, or 1500 (1.5mm) for porcelain.

RADIAL THICKNESS is your minimal thickness for the axial walls. Set to 500.

VENEER THICKNESS is 500. It only applies when you’re doing veneers in biogeneric, which is tedious and painful. You’ll correlate veneers.

ADHESIVE GAP is your kavo surface (margins except gingival) for inlays and onlays. It prevents binding or flash. Set to 30. Raise to 50 if your inlays aren’t going down easily.

SPACER is your internal spacer. The software gives you 100 microns immediately, but that’s not enough. Start at 30. If it feels loose, lower to 20 or 10. If it’s tight, raise to 50.

SCAN STEP is always 3, unless you’re a lab.


These aren't the "official" settings and if you find something else works better, keep it. I've found in the majority of offices these numbers are perfect, but you could be an exception. Every dentist is exceptional in some way!

Recommended Burs

I’ve been recommending burs for a long time, and I’ve finally come out with my own bur kit. It’s manufactured by Axis, sold by Patterson, and nets me absolutely no money... but I do get to say I have my own bur kit. The cost is $189 and you can get it from your Patterson rep or from the office by calling 408-746-4300 (ask
for customer service, say you want the CERECGuy bur kit). It comes with a bur block and the following burs:
- wicked course to cut off zirconia and PFMs
– 1.5mm and 2.0mm occlusal reduction burs
– course inverted cone to remove undercut
amalgams for inlays and onlays
– course cylinder to prep crowns
– fine cylinder to finish axial wall margins
– fine football to smooth internal angles
– fine mosquito tip to open interproximal
contacts for inlays and onlays
– two polishing cups for porcelain
– a robinson wheel (frilly edges) for polishing
- keys to a new Lambourghini (while supplies last)

You don't have to get this kit, but you do have to get appropriate burs to create the sharp margins and internally smooth angles necessary for CEREC. I recommend you reduce your bur inventory to no more than 10 different types (for every prep), then make 10 sets and place them in 10 bur blocks. Now no matter what you're prepping, you have a standard, familiar bur kit ready to go.