Class II on plastic teeth- Need advice

When I first started I used to use a 329 or 330 (let's say it was a MO) and started in the distal pit and extended to the mesial pit. Then I switched to a 169L for the box, to take out the most of the marginal ridge, and place the reverse S curve. To make sure I didn't accidentally cut the adjacent tooth I left a thin shell of "enamel" and used my hatchet to break the shell (you could also use a matrix band to protect the adjacent tooth). I've also had success with the 256 for the box...but now i just do the whole thing with a 330.

I hope that helps!

Same thread was posted a month or two ago.

Also depends on what school of thought you're taught. Some schools teach converging B/L prep walls, some teach parallel walls with retention grooves. Some schools you spend a better part of operative learning amalgam preps then never do a single one clinically.

Ultradent inbetween to prevent damaging adjacent tooth. 330 on a high speed.

245 for just about everything...sometimes use a 55 or 56 for box to keep from having an undercut axial wall (pulpal floor overhang)

330 for pits to 1.5mm, connected, then run the 330 for the entire outline form (at 1.5mm depth). Switch to 245 typically to drop the box(es), smoothing out with 256, usually all on high speed. Hand instruments to get the final breaks in contact, marginal trimmers and hatchets... Sometimes I drop the box with a 956 to help avoid damaging adjacent teeth, or use a matrix band

They teach us to converge the B-L walls at OSU, so the 330 works well for that, why remove excess tooth structure to make them parallel and take out retention grooves?

JamesOSU said:

They teach us to converge the B-L walls at OSU, so the 330 works well for that, why remove excess tooth structure to make them parallel and take out retention grooves?

Click to expand...

And then I say 'Why leave unsupported enamel at the cavosurface margin and make the tooth more prone to cuspal fracture?'

And the debate goes on and on and on and on and on and on and on and on....

armorshell said:

And then I say 'Why leave unsupported enamel at the cavosurface margin and make the tooth more prone to cuspal fracture?'

And the debate goes on and on and on and on and on and on and on and on....

Click to expand...

or more realistically I say "No one really uses amalgam any more so who cares"

ideal preps, probably 330. Bigger preps I use 556 and 330. If you find you have some "unsupported plastic" might I recommend a GMT to remove it rather than a hatchet on these plastic teeth.

Person above me is right.

armorshell said:

And then I say 'Why leave unsupported enamel at the cavosurface margin and make the tooth more prone to cuspal fracture?'

And the debate goes on and on and on and on and on and on and on and on....

Click to expand...

No. Just on and on (once).
There wouldn't be any unsupported emanel as long as your cavosurface angle is close to 90. which automatically gives convergent walls. Unsupported enamel happens when the walls are exceedingly convergent.

On the other hand, making the walls parallel will protect the enamel but will give the amalgam acute angle margins more prone to fracture unless you undercarve the occlusal which is not always possible.

After all there is no real difference, Armor. They all will go in the big bucket you will be carrying around later in the summer.