Platelet rich fibrin is not a barrier membrane! Or is it?

Table 1 Different names/terminologies related to membrane and their meanings

Sr. No.	Terminologies	Meanings/definition
1	Membranes	A thin pliable sheet of material or tissue forming a barrier or lining.
2	Resorbable membranes	Membranes that are biocompatible and are metabolised by hydrolysis or enzymatic activity over the course of time.
3	Non-resorbable membranes	Membranes that are bio-inert and require a second surgical procedure to remove after bone regeneration is complete.
4	Barrier membranes	A barrier membrane is a device used in oral surgery and periodontal surgery to prevent epithelium, which regenerates relatively quickly, from growing into an area in which another more slowly growing tissue type, such as bone, is desired.
5	Collagen membranes	Membranes made of collagen (mostly type-1 collagen) that are fabricated in different shapes and sizes and used in oral surgical procedures for bone and tissue regeneration.
6	Collagen barrier membranes	Selective collagen membranes that can act as barrier membrane for bone and tissue regeneration.
7	Natural membranes	Membranes made from natural materials or sources, such as collagen, dermis, tendons, sclera, amnion, pericardium, chorion, and silk.
8	Synthetic membranes	Membranes made from synthetic materials, such as polytetrafluroethylene, titanium, and ceramic.
9	GTR membranes	Barrier membranes used for regeneration of lost PDL, cementum, and bone.
10	GBR membranes	Barrier membranes used for bone regeneration.
11	PRF membranes	Autologous membrane made via blood centrifugation followed by compression of clot to the desired thickness.
12	Multiphasic membranes	Multiphasic membranes that are designed in phases (or layers) to meet the various criteria of the periodontal tissue types.
13	3D-printed membranes	Customised zirconia printed via the CAD CAM technology to serve as new-generation barrier membranes.
14	Functional membranes	Membranes that are not passive barriers but are actively functioning in supporting the regeneration process.
15	Bioactive membranes	Membranes that are loaded with different biological activities, which are timed to play a role in different stages of bone healing and mimic the natural osteogenesis process.
16	Antimicrobial membranes	Barrier membranes loaded with antimicrobial components such as antibiotics, silver ion coating, PEG, superhydrophobic and structural coating.
17	Structurally layered membranes	Multiple layered membrane that are structurally engineered so that each layer has a different biological characteristic.
18	Polymer barrier membranes	Membranes made from polymers such as polylactic acid, polyglycolic acid, collagen, and alginate.

GTR: Guided tissue regeneration; PDL: Periodontal ligament; GBR: Guided bone regeneration; PRF: Platelet-rich fibrin; CAD CAM: Computer-aided design computer-aided manufacturing.

Table 2 List of review articles on barrier membranes

Sr. No.	Ref.	Was PRF included in the list of barrier membranes?
1	Dimitriou et al[11], 2012	No
2	Rakhmatia et al[26], 2013	No
3	Soheilifar et al[27], 2014	No
4	Lee et al[6], 2014	No
5	Rodriguez et al[29], 2018	No
6	Caballé-Serrano et al[7], 2018	No
7	Omar et al[32], 2019	No
8	Higuchi et al[33], 2019	No
9	Caballé-Serrano et al[47], 2019	No
10	Aprile et al[42], 2020	Yes (only mentioned)
11	Sasaki et al[34], 2021	No
12	Ren et al[39], 2022	Yes (as a supportive bioactive molecule to other barrier membranes)
13	Yang et al[38], 2022	No
14	Alauddin et al[35], 2022	Yes (as a supportive membrane)
15	Solomon et al[46], 2022	Yes (for increasing the soft tissue thickness)

PRF: Platelet-rich fibrin.