Lips are notorious for swelling after procedures, trauma, etc. As long as the swelling is soft and the overlying skin has normal color, it is unlikely that there is infection. Now that several days have past since the injection, you might try applying heat to the area. My expectation is that your swelling will resolve over the next several days.
Oftentimes, irregular soft tissue appearance can be improved by resurfacing the area with a laser. I like to use the Er:YAG laser to improve the appearance of scars left from previous oral surgery or trauma. The laser is minimally invasive and leaves the area smooth with minimal postoperative bleeding or pain. Sometimes it takes several treatments to achieve the best result.
I have used the Zimmer trabecular metal implant in a case similar to yours with good success. Sounds like a reasonable time to use this implant.
Like others who have answered, I support grafting at the time the tooth is extracted. It is prudent to take antibiotics prior to the extraction. Once the tooth is out of the socket, the surgeon can thoroughly clean and disinfect the area prior to placement of the graft. Even when there is no infection present, we are always asking our bone grafts to heal in the presence of bacteria. It is simply the nature of working in the mouth.
If the denture is not too old and the denture teeth are in good condition, it might be possible to place a new base on the existing denture at the same time the housings are captured. Although there is a charge to place a new base on the denture, the cost would be less than a new complete denture. This assumes that you are happy with the shape, size and color of the teeth on the existing denture.
