Tell me about the rebuilding of a buccal wall (after extraction) for a upper molar if there is enough remaining bone to work with? new to this.

For an implant?: After tooth extraction, assuming (4) walls are preserved, the body will fill with blood clot, and ultimately fill in with bone. Over time, especially in the 1st year, you will see bone resorption in 2 directions (loss in height, and width). Bone thickness plays a factor in creating an ideal site for an implant and final crown. You need enough bone for the implant, and to support the soft tissue.

Many methods: There are many advanced techniques that periodontists (and oral surgeons) use to increase the available bone necessary for a dental implant when there is insufficient bone mass for placement and success of a dental implant. It may include "splitting" the ridge and inserting bone graft material, adding to the existing bone with graft and membranes, or sinus lifts, or combinations of these methods.

Simple Solution: You can get a bone graft done during or after the extraction.