One Stage Surgery:
The one stage surgery means that the day that the implant is placed a healing abutment is placed and sits above the gums. The pros to a one stage is that there is no second surgical procedure to uncover it at a later date. One stage surgery is great when there is good initial stabilization (tight fitting to bone) of the implant and minimal risk of infection.
Two Stage Surgery:
With two stage surgery, the day the surgery is performed the implant is completely covered. Three to six months later another surgery is done to expose the implant and place the healing abutment. The type of surgery chosen is determined by the amount and quality of bone that you have at the time of surgery. Reported by Scott Young.