So the most common question I get when doing a crown(cap)is why do you need novocaine just to take an impression...well this post will help answer that question...
In fig. 1 we have what appears to be a very nice tooth....
but in fig. 2 I have drawn an outline around what is a large tooth colored filling existing in this tooth....we are going to prep this tooth for a crown and take an impression....
After preparing the tooth I have to take a rubber impression of the tooth so that my lab tech can fabricate a well fitting cap...but how do we get the rubber material to completely surround the lowest edges of the tooth at the gum line??
Well... we have to convince the gums to go away...at least temporarily...so that I can squirt some of the rubber to the edge of my preparation...and how do we do that...??
Well....we gently insert a small string or piece of chord into the space between the tooth and the gum...see fig. 3 and you can see the small space into which we place a layer of the string...
In fig. 4 you can see the space with the string in place...
And when I remove this string there is a nice little trough around the entire tooth into which I can squirt the rubber for my impression...see arrows in fig. 5
And this is why you need novocaine for an impression..the physical displacement of the gums to accomodate the rubber impression material is not something you want done without some anesthetic!!
After the impression was taken I placed a temporary crown and will try in the permanent crown next week...fig. 6
See you next time...
No comments:
Post a Comment