No flap, no membrane?

Agree… Except that when dealing with a mandibular molar that has an intact buccal plate and adequate soft tissue then any dimensional improvement offered by the addition of a graft is far from being of clinical significance. Protocol driven dentistry ignores the common sense factor and Case Selection Matters

Honestly since I passed my Perio Boards in 2007 I have sort of abandoned the idea of evidence based dentistry as portrayed in the various dental journals. In my opinion everything since the classic GTR studies by Bowers and the original GBR studies by Buser has just been a new shade of lipstick on a pig. I finally learned to read the materials and methods as well as the source of funding for these “Scientific Articles” and discovered that most of them are just billboards for the various biological companies and authored by the same teams of professional dry finger authors. I think “WE” as a profession have lost sight of clinical significance vs. statistical significance, which can be adjusted to satisfy the desired outcome, and have become fascinated with trying to manipulate Mother Nature.

Hello, the protocol in describe has been in use for over 15 years in uk and Europe and to a lesser extent in USA. There are numerous publications and case studies with histology as the measure. Look up key words minimull intervention/form stable/synthetic. Authors such as Leventis, Fairbairn.
As to your second point. I was involved in the earlier studies in membranes for GTR and then GBR. Primary reasons were:

  1. to create space.
  2. contain a mobile particulate.
  3. Prevent graft micro movement.
  4. Hinder entry of soft tissue from the healing space.
    1,2 and 3 are not needed if a form stable graft is used. Hypotheses is that item 4 is not invasion but replication of granulation tissue not removed prior to grafting. If a mineralised graft is used (most proprietary allografts and all proprietary xenografts) its impact is less than a fully resorbing graft simply because it is more efficient than oseoid and there is much less space for the granulation tissue to occupy.