Slight separation of teeth in the matrix band for Amalgam Restoration

[nguyenkimphat]

Hello everyone 🙂

I was told that a properly placed amalgam class 2 matrix will provide slight separation of the teeth to accommodate for the thickness of the matrix band material.

What does this mean? Can someone please provide a quick cartoon diagram of this so that I can visualize the "slight separation of the teeth."

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[punchdrunk7]

What school do you attend? They should be showing you this. You should buy an operative book and there will be plenty of diagrams.

 

[sgv]

It's called breaking contact. When viewing from the buccal or lingual of the proximal box, you should be able to see past through the other side. Or, similarly, you should be able to pass a 0.5 mm explorer tip just barely through the proximal contact. Or, again, you should be able to freely slide a matrix band into the contact area.

I can't find a good picture. But take a look at this guy. The distal box of the top picture didn't break gingival floor contact. In the bottom picture, the distal box broke gingival floor contact with the adjacent tooth which is why you're able to see the gingiva from the occlusal view. You should not be able to slide an 0.5 mm explorer tip through the gingival floor contact. You should only just barely see the gingiva. If you can fit a 0.5 mm explorer tip that means you may have cut too far gingivally. The explorer tip should only be able to pass through between the box's buccal/lingual axial walls and the adjacent tooth.

So you need to see two things at the box when checking for broken contact. Pink gingiva when viewing from the occlusal view and the opposite side when viewing from the buccal or lingual view.

 

[Bis-GMA111]

not breaking gingival contact clearly is an ''auto fail'' at my school for practical examination purposes...and i'm pretty sure that's the standard everywhere. you want to make sure that this contact is broken.

i also feel like that statement is misleading. yes there should be a space for a matrix band, but it's not there to accommodate a matrix band...the space is there due to breaking gingival contact to access the caries. you break the contact, and as a result of THAT, a separation is created which allows for the placement of a matrix (be it a tofflemire or v3 system)

@nguyenkimphat

also to add on to what @sgv said, there is no 'minimum' depth for breaking gingival contact. you want to keep going, carefully, until you can see a sliver of gingiva. if you see a big gap, chances are, you've broken part of your gingival floor and you'll need to make your prep larger axially to make a little more of a floor to accommodate the filling material.

always do this part very carefully, because when you first start out it's easy to break the floor, go down slowly, and keep checking along the way to see if you've broken contact. always make sure the area is free of any debris. when in doubt about breaking contact, try doubling up a piece of floss to clean out the contact area. you should also here a light snap when you do this. works like a charm.