Amalgam vs Resin Prep differences?

[bballrules]

Hello, I was wondering how an amalgam and a composite prep are different. They say composite is more conservative. Does that just mean it's smaller? Do the dovetails or retention change? For example like the retention under cusp(converge) or dovetails(diverge). We're starting composites next week and I wanted help on how to prep them.

Also, what instruments are used to remove calculus. I know the 11-12 explorer is used to detect, but I'm not sure which graceys are used to remove, especially which graceys correspond with mesial or distal. There's so many graceys I don't know which is the "go to" one. Thank you for all your help!

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[Streetwolf]

Hello, I was wondering how an amalgam and a composite prep are different. They say composite is more conservative. Does that just mean it's smaller? Do the dovetails or retention change? For example like the retention under cusp(converge) or dovetails(diverge). We're starting composites next week and I wanted help on how to prep them.

Also, what instruments are used to remove calculus. I know the 11-12 explorer is used to detect, but I'm not sure which graceys are used to remove, especially which graceys correspond with mesial or distal. There's so many graceys I don't know which is the "go to" one. Thank you for all your help!

For an occlusal composite you could just remove the area with caries and not open the rest of the grooves. Make sure the depth is good and the area is open enough to instrument the composite. Remember you have mechanical retention with composite. You could also do slot preps for class IIs without the occlusal segment.

For scaling I generally use a sickle scaler on anterior teeth and a 13/14 scaler on the posteriors. There's a 2R/2L for the anterior and 4R/4L for posteriors but the 13/14 is universal so I tend to stick with that. You are right that the 11/12 is to detect calculus.

 

[Synlar]

Amalgam needs to be at least 2mm in depth, and the width has to be at least enough to fit your smallest packing instrument. Also, amalgam doesn't bond to enamel, so that's why amalgam preps should be converging occlusally, and you have retention grooves.

Composite bonds really nicely to enamel, so that gives your retention. This means no need for retention grooves, and your walls are pretty parallel (as opposed to converging occlusally). There is no minimum depth of your prep needed. Because of the bond to enamel is nice, you'll learn about bevels (Not so much for class 1 or 2). Oh, and composite can bond to composite, and you can take your time with it!

 

[bballrules]

Thanks Streetwolf. I wanted to ask you again about the composite prep. For amalgams, I usually use the 330 because it automatically gives me the undercut and I can just hold the bur straight. For the dovetails, I just lean over a little for the divergence. I'm still a little confused on what the composite prep looks like. Since there are mechanical undercuts, are all the walls just straight? Am I suppose to do the whole prep with a straight bur like the 557? Is it okay to do the same exact thing I do with amalgam preps for composites? I don't understand what exactly changes(or what the diff between amalgam and composites are). Thanks again, I appreciate it

 

[Synlar]

There's no undercuts needed for composite.
I thought 330 was straight? I use that or 257 for composite preps, and 245 for amalgam (245 is pear-shaped, gives the undercuts...)

 

[bigstix808]

Thanks Streetwolf. I wanted to ask you again about the composite prep. For amalgams, I usually use the 330 because it automatically gives me the undercut and I can just hold the bur straight. For the dovetails, I just lean over a little for the divergence. I'm still a little confused on what the composite prep looks like. Since there are mechanical undercuts, are all the walls just straight? Am I suppose to do the whole prep with a straight bur like the 557? Is it okay to do the same exact thing I do with amalgam preps for composites? I don't understand what exactly changes(or what the diff between amalgam and composites are). Thanks again, I appreciate it

with composite you'll just use the bur shape that best fits the surface you're working on. class III on 7, open up with a small round bur, class I on 30, prob use some sort of straight edge or flame bur (depending on how deep the groves may look. once you're through enamal and you have a good outline form, grab you a big 'ol round bur on your slow speed and go diggin out the caries. pulpal floor does not need to be flat like you'd want for an amalgam. no need for retention form, well maybe for a conservative class II (just dont leave unsupported enamal) and your resistance form (ie: dove tails) are not really required. chances are you'll end up making slight bevels in all your cavosurface margins on most composite preps as it "exposes" more rods for composite to bond to.

basic rule of thumb for composite prep... see caries - remove caries - fill in the hole

and a 330 is pear shaped not straight.

 

[Ryltar]

Amalgam needs to be at least 2mm in depth, and the width has to be at least enough to fit your smallest packing instrument. Also, amalgam doesn't bond to enamel, so that's why amalgam preps should be converging occlusally, and you have retention grooves.

Composite bonds really nicely to enamel, so that gives your retention. This means no need for retention grooves, and your walls are pretty parallel (as opposed to converging occlusally). There is no minimum depth of your prep needed. Because of the bond to enamel is nice, you'll learn about bevels (Not so much for class 1 or 2). Oh, and composite can bond to composite, and you can take your time with it!

For class 1 preps on #20, #19, and #30, I've learned to do composite preps at about 1.5mm (no less) depth, and amalgam preps at 1.5-2mm.

 

[Streetwolf]

I don't understand what exactly changes(or what the diff between amalgam and composites are). Thanks again, I appreciate it

Maybe your instructor is making you continue with "ideal" preps just for the sake of doing them?

If I'm doing a composite on #30 and the caries is just on the distal part of the occlusal surface, I'll go in with a 556 in that one spot.... should just look like a circular prep. I'll open it enough so that I can go in with my slow speed round bur and get out the caries. I'll make sure it's big enough to fit a composite instrument into. Once the caries are out and I know I can instrument the composite, I'll restore it.

 

[SeattleRDH]

For an occlusal composite you could just remove the area with caries and not open the rest of the grooves. Make sure the depth is good and the area is open enough to instrument the composite. Remember you have mechanical retention with composite. You could also do slot preps for class IIs without the occlusal segment.

For scaling I generally use a sickle scaler on anterior teeth and a 13/14 scaler on the posteriors. There's a 2R/2L for the anterior and 4R/4L for posteriors but the 13/14 is universal so I tend to stick with that. You are right that the 11/12 is to detect calculus.

Here you go:

Anterior sickles are mainly for superficial deposits on anterior teeth. You can go a little subgingival on a prophy but if you have deep pockets (3mm or more) on the anteriors you should use a gracey 1/2. Or a Gracey 13/14 if you know how to use it in the non-traditional way. (remember that graceys are NOT universals so use the correct side of the instrument)

Usually when we say "13/14" we are referring to a Gracey 13/14 which is specific to distal surfaces of posterior teeth. If you use this for posteriors then you should also be using a Gracey 11/12 which is for mesial surfaces. There is a universal called Columbia 13/14 which I use frequently but don't confuse this with a gracey - they are VERY different.

My prophy set-up looks like this:
Sickle
Columbia 13/14
4R/4L (also a universal but with less bend and a longer shank)
Gracey 13/14
Gracey 11/12

But I could do most prophies with just a universal and a sickle

My perio set-up looks like this:
Sickle
Gracey 1/2 (anteriors)
Gracey 11/12
Gracey 13/14
Gracey 15/16 (same as 11/12 but with more bend in the shank)
Gracey 17/18 (same as 13/14 but with more bend in the shank)
Mesial/Distal perio file
Buccal/Lingual perio file
Gracey 7/8 (good for cuspids, premolars)
4R/4L
Columbia 13/14

There are many more hygiene instruments besides what I've listed here but your school should have all of these basics. Just be careful with Graceys! There is a working edge and a non-working edge. Don't even worry about which Gracey goes with which surface just be able to figure out which is the working edge, orient it to the tooth, and go. You'll quickly figure out that it's virtually impossible to use a 13/14 on the mesial surfaces of molars.

 

[Streetwolf]

Sorry I didn't mean to say it was universal in the sense that it has all working edges. Oops haha. Yes there is definitely a working edge and a non-working edge.

What I meant was you can use it for anteriors and posteriors like you said.