Class II amalgam prep

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GoGatorsDMD

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I feel like I am getting seriously hosed by some sort of misfortune. However, I am not above the possibility that I am doing something wrong.

When I am planing the buccal or lingual wall of the proximal box to remove that thin candy shell of "enamel" a big chunk of the ivorine is coming off. This happened to me today on a freaking exam.

Am I being too aggressive in my planing? Is my hatchet messed up? Has this happened to anyone else with the ivorine? The profs tell me this doesn't happen with real enamel.

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Mine does that on the very center of the box if i break it off towards the mesial or distal. It just ditches it out in the middle for some reason.

Generally I'll try to stick a wedge in between the tooth i'm prepping and the adjacent to allow more room and try to run the hatchet along the floor of the box in a buccal/lingual direction.
 
I rarely use hatchet or anything similar. Use a needle point diamond bur to break the contact, to smooth out the walls.

This is what REALLY works for me:
1.Use #169 bur to cut the occlusal surface first and then the box. Don't use #56 because it'll make the outline too big, too fast!
2.Use a pointed end diamond bur to break the contacts and round sharp edges/unsupported enamel at the interproximal box. Use it to shape the pupal-axial wall into a convex shape. You can also use it to bevel the gingival floor.
3.Use #957 (end-cutting bur, it only has cutting end at the tip of the bur) to drop and smooth the pupal floor and gingival floor.

Hatchet is only good for smoothing the floors.
 
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Is it not wise to leave a very thin layer of the enamel (kavo teeth) on the interproximals of crown preps and box preps to chip away with a hatchet? It usually prevents any damage to the adjacent teeth for the most part.
 
CJWolf said:
Is it not wise to leave a very thin layer of the enamel (kavo teeth) on the interproximals of crown preps and box preps to chip away with a hatchet? It usually prevents any damage to the adjacent teeth for the most part.
DON'T DO IT! DON'T EVEN GO THERE!!! You're taking a chance of chipping away your lingual and buccal walls (of the interproximal box) and usually a piece of gingival floor.

Try using the pointed end diamond bur to break the contacts for kavo teeth and especially natural teeth. Open the contacts with that bur from the INSIDE of the box OUTWARD so that you won't damage the adjacent tooth.
Hatchet doesn't work in natural teeth. It'll take years to break to contacts and smooth out the walls!!! Also there's a chance of fracturing the tooth.

Also use a short, medium to course, pointed end diamond bur to break the interproximal contacts for a crown prep. So you won't end up cutting the adjacent teeth. Don't use the flat end diamond/chamfer....diamond to break the contacts in a crown prep. You either will nick the adjacent teeth or have a wide interproximal margins.

Try to do what I posted above. I usually get very good score for my competencies. I didn't have any problem with the WREB either (hopefully not!)
 
lnn2 said:
I rarely use hatchet or anything similar. Use a needle point diamond bur to break the contact, to smooth out the walls.

This is what REALLY works for me:
1.Use #169 bur to cut the occlusal surface first and then the box. Don't use #56 because it'll make the outline too big, too fast!
2.Use a pointed end diamond bur to break the contacts and round sharp edges/unsupported enamel at the interproximal box. Use it to shape the pupal-axial wall into a convex shape. You can also use it to bevel the gingival floor.
3.Use #957 (end-cutting bur, it only has cutting end at the tip of the bur) to drop and smooth the pupal floor and gingival floor.

Hatchet is only good for smoothing the floors.
Too many burs to make money in the real world.
 
use hatchets sparingly if at all... make sure they are very sharp
 
tx oms said:
Too many burs to make money in the real world.
True. One bur fits all in the real world?! "Time is money" but for now, that's what I would recommend for restorations in dental school (if they wanna do well!). You have many different type of burs for a good reason!
The only bur on OS is for the Striker! :eek:
 
Don't use a friggin hatchet for gods sake. Use a 556 or a 331 to drop the box and to break contact
 
When removing the protective enamel shell in a real tooth, you can rotate your hand instrument (an enamel hatchet or ging margin trimmer) -- this will cause the shell piece to cleanly fracture off due to the crystalline structure of enamel rods.

If you try this with amorphous ivorene, you're gonna get a jagged edge where the plastic shatters away from the rest of the tooth.

Try to make your hatchet SHARP (test it on your fingernail), and use it to CUT the shell from the occlusal to the gingival, not twist and break.

Sometimes I have to hold that stupid hatchet with my fingertips right up next to the cutting blade to keep it from putting too much pressure on the shell and fracturing it.
 
And...it's always a good idea to leave this shell as long as you can to protect the adjacent tooth. When it's "so thin you can read the Wall Street Journal through it," (according to one of our professors) you can stop expanding your box mesiodistally and cut the thing out.
 
use a flame shaped diamond



GoGatorsDMD said:
I feel like I am getting seriously hosed by some sort of misfortune. However, I am not above the possibility that I am doing something wrong.

When I am planing the buccal or lingual wall of the proximal box to remove that thin candy shell of "enamel" a big chunk of the ivorine is coming off. This happened to me today on a freaking exam.

Am I being too aggressive in my planing? Is my hatchet messed up? Has this happened to anyone else with the ivorine? The profs tell me this doesn't happen with real enamel.
 
329 (or 330) all the way
 
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Thanks for all the replies. We have another class II exam on Friday. I think I'm going to try the flame diamond to remove most of the shell and save the hatchet for just very minor planing.
 
texas_dds said:
329 (or 330) all the way


330 is what I use from start to finish. I just put in a wood spacer on the typodont to make sure I do not knick the adjacent tooth. Class II prep this way takes me about 10min and I score B or better on the practicals.

Speed = $$$ and soon our program will be production based so I guess that will equal some goodies. Although, if for you speed equals crappy work, don't do it!
 
Also you can loosen the screw on the bottom the tooth just a little which will make the tooth separate a little more when a wedge is placed. Another thing you can to is to cut a matrix band in half and then fold one of those halves in half and place it between the teeth. If the matrix band will not stay in place then use a whole matrix band and wrap it around the adjacent tooth and hold it in position with a wedge.


npayne said:
use a flame shaped diamond
 
texas_dds said:
329 (or 330) all the way
330 is perfect for occlusal prep, especially in Pedo. :thumbup:
 
ItsGavinC said:
The good ole' 330 dirty. :thumbup:
Whoever came up with that bur is a genius! That's the only bur that I use in Pedo. They don't have many burs selection anyway; the main purpose is drill and fill as quick as you can in pedo. Small like #169 but shorter so less chance of perf. One advice in Pedo, don't use the explorer to check for caries because there's a good chance you'll end up perf the pulp horn.
 
Brocnizer2007 said:
330 is what I use from start to finish. I just put in a wood spacer on the typodont to make sure I do not knick the adjacent tooth. Class II prep this way takes me about 10min and I score B or better on the practicals.

Speed = $$$ and soon our program will be production based so I guess that will equal some goodies. Although, if for you speed equals crappy work, don't do it!


10 mins? i have seen some incredibly fast people in the lab, but doing a class II prep in 10 mins certainly beats that. they should give you your DDS already.



as for me, depending on which tooth i prep, it could take me anywhere from 30 min-1 hr. (lets not talk about MOD on #5 :laugh: ).
as far as instruments go, i use the 330 for occlusal surface, then 169 to drop my proximal box, and then use my best friend "the hatchet" to even and smooth the walls. i dont know why you guys discourage people from using the hatchet but i find it very helpful.
 
PERFECT3435 said:
i dont know why you guys discourage people from using the hatchet but i find it very helpful.

I used the hatchet all the time in preclinic, however when I started seeing patients I found out that hand instruments struggle to cut enamel and dentin unless its carious. The hatchet worked for me in making my preclinic preps beautiful, but looking back it seems like a waste, when I could have been learning how to make my preps beautiful with a handpiece. I cant remember the last time I picked up a hatchet while doing a prep on a real patient.
 
Col Sanders said:
I used the hatchet all the time in preclinic, however when I started seeing patients I found out that hand instruments struggle to cut enamel and dentin unless its carious. The hatchet worked for me in making my preclinic preps beautiful, but looking back it seems like a waste, when I could have been learning how to make my preps beautiful with a handpiece. I cant remember the last time I picked up a hatchet while doing a prep on a real patient.


GOTCHA. makes sense.ty
 
245 all the way, from beginning.....to the end. One bur. Might break out the hand instruments to clean it up, but rarely.

No one else out there uses a 245??
 
lmgonza2 said:
245 all the way, from beginning.....to the end. One bur. Might break out the hand instruments to clean it up, but rarely.

No one else out there uses a 245??
I have a friend who uses a 244 and does a great job. To each his own. In the end, it comes down to knowing what you are doing and what you're comfortable with
 
lmgonza2 said:
245 all the way, from beginning.....to the end. One bur. Might break out the hand instruments to clean it up, but rarely.

No one else out there uses a 245??
I do. It's similar to 330, only longer.
 
lmgonza2 said:
245 all the way, from beginning.....to the end. One bur. Might break out the hand instruments to clean it up, but rarely.

No one else out there uses a 245??

245 for the occlusal then a 330 or 33-1/2 for the box.

Go study Gonz ;) ;) ;)
 
just use a 245 for the whole prep...don't waste your time with hoes or hatchets or you will be planing "enamel rods" all day. Get used to just using your high speed and things in the clinic will go a lot easier for you


rsweeney said:
245 for the occlusal then a 330 or 33-1/2 for the box.

Go study Gonz ;) ;) ;)
 
npayne said:
just use a 245 for the whole prep...don't waste your time with hoes or hatchets or you will be planing "enamel rods" all day. Get used to just using your high speed and things in the clinic will go a lot easier for you




Have you tried interdent guards? They slid between the teeth allowing you to get fast results w/out worring about adjacent teeth.
 
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