It is usual for a person to dream about a dead love one. One reason may be it's because we are missing the person so much.
The dream you that you had where in you are supposed to meet your father somewhere with your dentist friend but sad to say, you weren't able to meet him, signifies that you may have the strong desire to prevent his death and you were thinking that if only there is something you could do then, he might still be around. You have some regrets about losing your father. Perhaps, you might have lost a huge percentage of your inner strength when he died. That may be the reason why teeth is involved in your dream.
At the back of your mind, you may be thinking that if you could only turn back time, you would definitely do something to relieve and comfort your father from the burden he felt then.