15.3 Surgical Periodontics, Mucogingival Procedures, and Regenerative Care

6.3 Surgical Periodontics, Mucogingival Procedures, and Regenerative Care

When non-surgical periodontal therapy fails to resolve deep probing depths, or when anatomic, mucogingival, or intrabony defects persist, Phase II Surgical Therapy is indicated. The INBDE heavily emphasizes surgical flap design, resective vs. regenerative osseous surgery, mucogingival plastic grafting techniques, and tissue engineering concepts.

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Indications for Periodontal Surgery

Periodontal surgical intervention is indicated under the following clinical scenarios:

1. Persistent probing depths $\ge 5\text{--}6$ mm with active bleeding on probing post-SRP.
2. Inadequate access for root debridement in deep pockets or complex root anatomy (e.g., furcations, root concavities).
3. Infrabony (intrabony) osseous defects suitable for regenerative procedures.
4. Mucogingival defects (e.g., severe gingival recession, lack of attached keratinized tissue).
5. Need for crown lengthening prior to prosthetic restoration.

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Flap Architecture and Techniques

Periodontal flaps are categorized by tissue thickness and surgical position relative to the crestal bone.

Full-Thickness vs. Split-Thickness Flaps

• Full-Thickness (Mucoperiosteal) Flap: Includes the epithelium, lamina propria, and periosteum. Periosteal elevators detach the entire soft tissue complex from the underlying bone, exposing cortical bone. Indicated whenever osseous resective or regenerative surgery is planned.
• Split-Thickness (Partial-Thickness) Flap: Includes only the epithelium and underlying connective tissue; the periosteum is left attached to the bone. Indicated over thin radicular bone to prevent bone dehiscence or fenestration, or when placing free soft tissue grafts where an intact periosteal bed is required for vascular nourishment.

Common Flap Procedures

• Modified Widman Flap (MWF): An access flap utilizing internal bevel incisions to remove pocket epithelium and allow direct root visualization and debridement. The flap is not apically repositioned and no intentional bone removal occurs; results in minimal esthetic recession.
• Apically Repositioned Flap (ARF): The flap is elevated and sutured coronal to or at the osseous crest apically, eliminating pocket depth while increasing the zone of attached keratinized tissue.

INBDE High-Yield Constraint: An Apically Repositioned Flap can NEVER be performed on the palate. The palatal tissue is fixed keratinized mucosa devoid of an unattached mucogingival junction, making apical displacement anatomically impossible.

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Resective Osseous Surgery

Resective osseous surgery aims to modify bone contours to eliminate interdental craters and recreate physiological architecture.

Ostectomy vs. Osteoplasty

Osseous Architecture Terminology

• Positive Architecture: The interdental bone is coronal to the radicular (facial/lingual) bone margin across the arch (normal physiological state).
• Negative (Reversed) Architecture: Interdental bone is apical to the radicular bone margin (often caused by periodontitis interdental craters). Resective surgery performs ostectomy on radicular bone to restore positive architecture.

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Mucogingival Surgery and Plastic Procedures

Mucogingival procedures correct defects in the morphology, position, or amount of keratinized gingiva surrounding teeth or implants.

Free Gingival Graft (FGG) vs. Subepithelial Connective Tissue Graft (CTG)

Miller Classification of Gingival Recession:

• Class I: Marginal recession not extending to mucogingival junction (MGJ); no interdental bone/tissue loss. 100% root coverage expected.
• Class II: Recession extending to or beyond MGJ; no interdental bone/tissue loss. 100% root coverage expected.
• Class III: Recession extending to or beyond MGJ; interdental bone/soft tissue loss present or tooth malposition. Partial root coverage expected.
• Class IV: Severe recession extending beyond MGJ; severe interdental bone/tissue loss. 0% root coverage expected.

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Regenerative Periodontics

Regeneration is defined as the complete restoration of lost tissues, resulting in new alveolar bone, new cementum, and a new functional periodontal ligament (PDL).

Guided Tissue Regeneration (GTR)

GTR is based on the concept of cell exclusion using a physical barrier membrane (resorbable collagen or non-resorbable ePTFE):

[ GTR Cell Exclusion Principle ]
Barrier Membrane Blocks -> Fast-growing Epithelial Cells & Gingival Connective Tissue
Membrane Protects Space -> Allows Slow-growing PDL Cells, Cementoblasts, & Osteoblasts
Result                  -> True Regeneration (New Cementum + New PDL + New Alveolar Bone)

• Defect Selection: GTR achieves optimal predictable success in 3-wall intrabony defects (narrow, deep intrabony pockets surrounded by 3 bony walls) and Class II mandibular furcation defects.

Bone Replacement Graft Classifications

1. Autograft (Autogenous): Donor bone taken from the same individual (e.g., intraoral tuberosity, edentulous ridge, symphysis, or extraoral iliac crest). Gold standard possessing osteogenic (living bone cells), osteoinductive (inductive signals), and osteoconductive (scaffold) properties.
2. Allograft: Donor bone taken from a genetically non-identical individual of the same species (human cadaveric bone):
   • DFDBA (Demineralized Freeze-Dried Bone Allograft): Osteoinductive (acid demineralization exposes underlying Bone Morphogenetic Proteins / BMPs) and osteoconductive.
   • FDBA (Freeze-Dried Bone Allograft): Osteoconductive only (acts purely as a physical structural matrix).
3. Xenograft: Donor bone harvested from a different species (e.g., Anorganic Bovine Bone Matrix / Bio-Oss). Purely osteoconductive scaffold.
4. Alloplast: Synthetic inorganic materials (e.g., Hydroxyapatite, $\beta$-Tricalcium Phosphate / $\beta$-TCP). Purely osteoconductive filler.

Biologic Agents: Enamel Matrix Derivative (Emdogain / EMD)

Emdogain consists of porcine amelogenin proteins formulated in a propylene glycol alginate carrier. Applied to clean, root-conditioned (EDTA) root surfaces during flap surgery, EMD mimics the natural signals of tooth development, recruiting cementoblasts to deposit new acellular cementum and stimulating new PDL and alveolar bone regeneration.