Fallen screw

(Toronto, Canada)

I had a dental implant done three weeks ago where the oral surgeon put a screw, Now I have to wait a couple of months to make sure it heals. I felt good after two weeks and then suddenly today at a party the screw fell off and now I have a hole which is sensitive?

Is this common and what will the dentist do to fix it. Do I have to go for drilling and freezing again. What if it falls off again after the tooth is put? Should I ask the dentist for a refund and forget about it? What does this mean is it that the bone has rejected the screw?

I feel very sad that I have gone through pain, stitches,antibiotics and now the screw has fallen off ?

Any advice on this