Sorry... that states novocaine.. which isn't widely used anymore. I'm not even sure if they even sell it anymore. But perhaps lidocaine (which is widely used) can also cause a false positive.
I did a little research online. I can't find any scientific articles that specifically deal with positive test results of cocaine from the use of lidocaine (anesthetic) but it is mentioned a few times. Here's a website with the information posted for false positives. You may want to contact the writer of the article to see what his/her sources were.
http://www.med.nyu.edu/patientcare/library/article.html?ChunkIID=13837
Not to my knowledge, there is nothing that can cause a positive cocaine result.