The Axial Contours of Amalgam Restoration

[nguyenkimphat]

HI everyone

I was told that one of the important characteristics of a class 2 amalgam restoration needs to have correct "axial contours."

What are axial contours? What does the word axial mean? I have seen it used so many times.

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[sgv]

From the occlusal view, the axial internal wall of the box should follow the curvature of the tooth in the buccolingual direction. The axial wall shouldn't be a straight buccolingual wall. It should be a convex curvature that follows the external curvature of the tooth...the fact that I couldn't find a picture of an ideal axial wall prep shows how in the clinical setting, some preclinical practices matter very little.

 

[bigstix808]

good contour on the axial walls of #4 and #5

bad contour in the obvious areas #30 and #31

 

[Bis-GMA111]

@bigstix808

good lord that's a lot of overhang.

i find that to be pretty surprising because it's much harder to get that much overhang with an amalgam restoration, as compared to composite correct?

 

[bigstix808]

@bigstix808

good lord that's a lot of overhang.

i find that to be pretty surprising because it's much harder to get that much overhang with an amalgam restoration, as compared to composite correct?

those amalgams were clearly done without a wedge to ensure gingival seal is maintained once matrix is placed. it really depends, to answer your question. you'd likely get more overhang with amalgam mainly due to the force needed to pack the amalgam in the box. if using composite you won't use such condensation forces thus lessening your chance of over hang. i, however, use sonic fill for many of my restorations and don't require condensation at all which is a nice time saver.