what exactly is cavo-surface margin? unsupported enamel?

SDN Members don't see this ad. (About Ads)

I'm really sorry for this question but I just can't get around with the above definitions. Maybe I wasn't paying enough attention in class

Can anyone illustrate with some diagrams?

cavosurface margin = basically any junction of cut/uncut enamel in a cavity prep

Originally Posted by Vapor1122

cavosurface margin = basically any junction of cut/uncut enamel in a cavity prep

hey,
CSA- is the junction between the prepared &the unprepared surface of a tooth ( the same thing that vapor 1122 said)- dont get frustrated, u ll understand better when u start cutting ( cavity preparation)- if u r a freshmen, well u ll get the concept better on ur sophomore year. do not panic..

Unsupported enamel is like, this:





See how in the second picture, there is no dentin under part of the enamel layer on the occlusal? Because of this, it will fracture easily under normal occlusal forces. Hope that helped!

unsupported enamel is basically any area that is undercut leaving enamel unsupported by dentin

Cavosurface is where the internal structure of your prep meets the external portion of the tooth that you haven't cut.

Unsupported enamel is when the enamel has no dentin immediately underneath it.

cavosurface margin is just the outline of the prep you've cut when you look down on the tooth's occlusal surface.

unsupported enamel is exactly like it sounds....enamel that is not supported by dentin. if enamel is hanging over the edge and there is no dentin underneath it, then you have unsupported enamel. the reason why they will make you diverge and converge the walls of your prep is to avoid this.

when enamel is not sitting on top of any dentin, then its going to be weak and the piece of enamel may fracture off.

at my school undermined enamel is an automatic failure...dont do it.