Valid study design

From: Jim McGivney (mcgivney_at_nospam.winid.com)
Date: 02/27/05 

Date: Sun, 27 Feb 2005 22:41:16 GMT

I take a photo of a plaster model of a dental arch (upper or lower teeth).
>From the photo I can construct an overlay. There are two methods of
constructing overlays. Two different dentists will construct the overlays.
Each examiner will construct 40 overlays using each of the two methods.

There is a method to determine a numerical measurement of how much a
specific overlay deviates from the dental model. I have the measurements
for the 160 overlays.

I would like to present and publish this data. I have been told that
editors will insist on a p-value. I can obtain a mean and standard
deviation of the results of each examiner and of each method.

Does this sound like a valid study design ?

How do I calculate the p-value ?

Thanks in advance for your help.

Jim