I wouldn't recommend using sharp tools to clean out the gunk that gets trapped between the screen and the bezel. You might try compressed air or the corner of a piece of paper. You can also pop the faceplate off quite easily, should you like to go that route.

I would recommend against this as well.

A common problem with the N800 tablets is that touchscreen response becomes extremely erratic or stops working entirely. Often this is due to some bit of debris having become stuck between the bezel and screen. Once the debris is cleared away, the constant pressure reading at that location ends, and normal touchscreen functionality is restored.

Preventing the problem by blocking the debris is a laudable goal, but I'm concerned that anything that seals the gap well enough to keep out dirt would itself put pressure on the screen.