I woke up last saturday with a toothache in my upper left teeth. went to two dentist which took x-rays and said there was no infection. the pain went away on wednesday had another set of x-rays on friday along with a cleaning. no infection according to

And your ? is?: It appears you would rather take the advice of dentists on the internet who cannot personally examine you, nor see x-rays of your teeth? You need to find a dentist whom you trust. If you do, take his\her advice. If not, find another one on a recommendation.

Sinus or muscle: if pain was in upper back teeth, could have been your sinuses causing pressure on the roots of those teeth, which can lead to tooth pain. If sinuses were not bothering you, could have been referred pain from a muscle in the head/neck area that had tightened up on you. It's called a trigger point. A point like this in your temporalis muscle(on the side of head) could refer pain to your upperteeth

I think you are ok: Im not sure what your question is. You saw two different dentists who said that you are ok. You are now without pain. If you have further concerns or questions call either one of the dentists.

Monitor: The tooth may be fine, but should be monitored closely every dental visit and by yourself.

Sinuses ?: A distinct possibility. Glad you're feeling better.