The referring GPs do most of the scaling and root planning before they refer the patients to the periodontists
.this is known as intial therapy. When the initial therapy fails to reduce the deep pockets, the periodontists have to do the open flap sugeries and do more scaling and root planning to remove the calculus that the GPs fail to remove. Many periodontists hire in-house hygienists but my wife usually refers the patients back to the GPs for periodic cleanings.
When my wife first took over an existing perio practice10 years ago, she did mostly osseous (pocket reduction) surgeries, free gingival grafts and bone grafts etc
..less than 10 % of the procedures were implant placements. Now at her own practice and at the GP offices where she works as an in-house periodontist, the majority of the procedures (70-75%) are implant placements and implant-related bone grafts. She does, on the average, 2-3 canine exposures a month for the orthodontists.