Is this safe or okay for now?

My top right wisdom tooth had pieces breaking off of it.  I wanted to get into a dentist office as soon as I could, but since it was before Christmas I didn't want to ruin any plans I had of cooking for the whole family if it needed to be pulled out.  So I waited.  Now, it's been 3 weeks since I first noticed the pieces breaking off.  I had a huge piece come off a day ago.  It really started being hot, cold, and touch sensitive and just overall achy feeling. I knew that no dentist office would be open on New Years Eve.  I figured I would just wait until Monday to call. Yesterday morning was when I had the huge piece fall off and I noticed it had some gray around the edges.  It was hurting pretty good so I did some looking around on the web to find something to fill it just to keep any food getting in it or more pieces falling off and exposing the nerves.  I found some stuff that's called Temparin which is made of zinc oxide.  I found out that is what dentists use in their temporary fillings.  This stuff I found said it is for lost fillings and crowns that have came off.  So I brushed and rinsed my mouth and the wisdom tooth really really good.  I used just enough to fill the hole and any sharp edges.  

I was just wondering if this is okay to do.  I'm not leaving it there forever and I hope I can get in sometime around the next few days.  Also, if there is a cavity is there any harm in covering it up with this stuff for now just until I get in to see the dentist?  And, how long could I keep this stuff in the tooth so I know what kind of time I should give the dentist before I have to find one that can get me in?  (sometimes to get a tooth fixed it takes my dentist about a month or longer. he is always booked for a long time)