Root Coverage Surgery Flap Thickness Classification
Direct Answer
Among the root coverage procedures listed, only the coronally advanced flap and laterally displaced flap utilize split-thickness dissection techniques, while free gingival grafts and connective tissue grafts are themselves tissue grafts rather than flap procedures. 1, 2
Coronally Advanced Flap: Split-Full-Split Approach
The coronally advanced flap employs a hybrid split-full-split dissection technique, not purely split-thickness throughout. 1, 2
Specific Dissection Layers by Anatomic Zone:
- Split-thickness dissection is used for the surgical papillae to preserve blood supply and prevent necrosis 1, 2
- Full-thickness dissection is performed for soft tissue immediately apical to the root exposure to maintain periosteal attachment 1, 2
- Split-thickness dissection returns for vertical releasing incisions to maximize flap mobility 1, 2
- Split-thickness dissection is used apical to previously exposed bone 1, 2
This approach balances flap mobility for coronal advancement against blood supply preservation 2. The split-thickness components allow the flap to advance coronally without tension, while the full-thickness zone maintains regenerative potential 1.
Laterally Displaced Flap: Variable Thickness Technique
The laterally moved, coronally advanced flap modification uses different thickness during flap elevation, incorporating both split and full-thickness components. 3
- The modified approach combines split-thickness dissection in donor areas with strategic full-thickness zones 3
- This technique achieved 97% root coverage and 80% complete coverage in 120 isolated recessions at 1-year follow-up 3
- The variable thickness approach preserves gingival margin position at the donor site while increasing tissue thickness at the recipient site 3
Free Gingival Graft: Not a Flap Procedure
The free gingival graft is a tissue graft harvested from the palate, not a flap procedure with thickness variations. 4
- This is a full-thickness epithelialized graft removed completely from the donor site 4
- The graft is secured with 5-0 or 6-0 monofilament non-absorbable interrupted sutures 4
- Expected outcome is at least 1.5mm of keratinized tissue width, the minimum threshold for long-term gingival margin stability 4
Connective Tissue Graft: Subepithelial Tissue Harvest
The connective tissue graft is harvested as subepithelial connective tissue from the palate, not created through flap dissection at the recipient site. 1, 5
- The graft itself is de-epithelialized connective tissue placed under a coronally advanced flap 1
- The recipient site flap (coronally advanced) uses the split-full-split approach described above 1, 2
- Connective tissue graft under coronally advanced flap demonstrates superior long-term stability with 87.0% root coverage at 12 months versus 71.7% with enamel matrix derivatives 6
- At 5-year follow-up, connective tissue grafts maintained 89.35% mean root coverage compared to 74.10% with growth factor approaches 1
Critical Clinical Distinction
The fundamental error in the question is conflating graft procedures with flap dissection techniques. Free gingival grafts and connective tissue grafts are tissue transplants, not flap elevation methods. Only the coronally advanced flap and laterally displaced flap involve actual flap dissection with varying thickness approaches 1, 2, 3.
When Full-Thickness Elevation is Mandatory:
- When performing rhPDGF-BB-mediated regenerative procedures to prevent flap collapse 1, 2
- When placing bone graft materials to prevent new bone formation collapse 1, 2
- When incorporating growth factors with bone grafts to prevent material displacement 2