chemically numbed

I spent my Friday afternoon in the dentist's chair. Yay me. I have had thousands of hours of dental and orthodontic work done on my teeth -- fillings, braces, extractions, root canals, and crowns -- but today I had a first. I had to have a filling on the front of one of my molars (usually it is the top). The tooth had become decalcified and though they had tried to seal it twice, the sealant was not enough... so today, a filling. In addition to this one, which required the dentist to stretch the gum away from the tooth in order to drill (!!), I was also having a crown prep on the next molar over. Once she had that tooth partly prepared, it exposed the next molar, which had a cavity hiding under an old filling (there was apparently a crack on the lingual) so that, too, had to be dealth with.

Normally, I require a lot of freezing -- usually double the average dose -- and today it took three doses. This got me thinking about what is in anesthetic and how exactly does it work? More important, what happens to it in my body? Is it possible to overdose? Will it build over time? Is there anything else I should know? Basically all of these questions were answered by the linked article from RxMed on Xylocaine® dental solutions. I still don't really understand how it works... but I am sure I can pull out some of this knowledge at a cocktail party....