24.10 Re-Evaluation, Endpoints and Periodontal Surgery

4. Step 3: Re-Evaluation and Endpoints of Therapy

Re-Evaluation Timing (8 to 12 Weeks)

Re-evaluation must occur 8 to 12 weeks post-Step 2 debridement. Evaluating earlier than 8 weeks records immature healing, as collagen remodelling and epithelial re-attachment require up to 3 months to achieve structural stability.

Clinical Endpoints of Active Periodontal Therapy

Under BSP guidelines, a patient has achieved successful endpoints of active therapy when:

1. Probing pocket depths are $\le 4\text{ mm}$ without bleeding on probing (BOP).
2. Absence of deep pockets $\ge 6\text{ mm}$ exhibiting bleeding.
3. Full-Mouth Plaque Score (FMPS) $< 20%$.
4. Full-Mouth Bleeding Score (FMBS) $< 10-15%$.

Management Algorithm at 8–12 Week Re-Evaluation
  │
  ├── Site displays PPD ≤ 4 mm with NO BOP?
  │     └── YES ──> POCKET CLOSURE ACHIEVED. Transition patient to Step 4 (SPC).
  │
  ├── Site displays PPD 4–5 mm WITH BOP?
  │     └── YES ──> RESIDUAL INFLAMMATION. Repeat Step 2 subgingival instrumentation.
  │
  └── Site displays RESIDUAL DEEP POCKETS PPD ≥ 6 mm (especially with vertical defects)?
        └── YES ──> Assess patient engagement (FMPS < 20%, FMBS < 30%).
                    ├── Compliant & Motivated ─> Consider STEP 3 ADVANCED SURGICAL THERAPY
                    └── Poor Compliance/Plaque ──> Repeat non-surgical Step 1 and Step 2.

5. Surgical Periodontal Therapy: Resective vs Regenerative

Periodontal surgery (Step 3) is indicated exclusively when residual deep pockets ($\ge 6\text{ mm}$) persist following high-quality non-surgical therapy.

[!IMPORTANT] Mandatory Prerequisites for Periodontal Surgery: Surgical intervention is strictly contraindicated in unmotivated patients with poor home care. Before any surgical flap is elevated, the patient must consistently demonstrate:

1. Full-Mouth Plaque Score (FMPS) $< 20%$;
2. Full-Mouth Bleeding Score (FMBS) $< 30%$;
3. Effective compliance with smoking cessation and systemic risk control.

Resective Periodontal Surgery

Resective procedures aim to surgically eliminate the soft tissue pocket wall or recontour osseous architecture to facilitate personal plaque maintenance:

• Gingivectomy: Surgical excision of the diseased gingival pocket wall.
  • Indications: Suprabony pseudopockets, drug-induced gingival enlargement (DIGE), altered passive eruption.
  • Contraindications: Infrabony pockets extending apical to the alveolar crest; situations where pocket excision would remove all attached keratinized tissue, violating the mucogingival junction.
• Apically Repositioned Flap (ARF) with Osseous Recontouring: A full-thickness flap elevated and sutured apically at the level of the recontoured alveolar crest. Osteoplasty (removal of non-supporting bone) and ostectomy (removal of supporting bone) eliminate osseous craters. Primarily restricted to posterior non-aesthetic zones due to severe subsequent root exposure.

Regenerative Periodontal Surgery

Regenerative surgery aims to recreate the lost periodontal attachment apparatus: new cementum, inserting periodontal ligament fibres, and alveolar bone.

Infrabony Defect Morphologies (Goldman & Cohen)

       3-Wall Defect               2-Wall Defect               1-Wall Defect
  (Three Osseous Walls Intact)   (Two Osseous Walls Intact)   (One Osseous Wall Remaining)

      │     Tooth     │             │     Tooth     │             │     Tooth     │
      │               │             │               │             │               │
    ┌─┴───────────────┴─┐         ┌─┴───────────────┴─┐         ┌─┴───────────────┴─┐
    │ [Bone]   ▲  [Bone]│         │ [Bone]   ▲        │         │          ▲        │
    │ [Bone] ◄ ● ►[Bone]│         │ [Bone] ◄ ●        │         │          ●        │
    │ [Bone]   ▼  [Bone]│         │ [Bone]   ▼        │         │          ▼        │
    └───────────────────┘         └───────────────────┘         └───────────────────┘
    (Highest Predictability)      (Moderate Predictability)     (Poor Predictability)

Regenerative Biomaterials and Biologics

1. Enamel Matrix Derivative (EMD / Emdogain): Purified hydrophobic porcine enamel matrix proteins (amelogenins) in a propylene glycol alginate carrier. Amelogenins mimic the biochemical cues of tooth development (Hertwig's epithelial root sheath), inducing mesenchymal stem cells on the root surface to differentiate into cementoblasts. Promotes true formation of acellular extrinsic fibre cementum, periodontal ligament, and alveolar bone.
2. Guided Tissue Regeneration (GTR): Placement of a mechanical barrier membrane (resorbable porcine collagen membrane or non-resorbable expanded polytetrafluoroethylene [ePTFE]) between the gingival flap and the root. The membrane physically prevents rapidly migrating gingival epithelial cells and gingival connective tissue fibroblasts from contacting the debrided root surface, permitting slower-growing pluripotent periodontal ligament and perivascular osteogenic cells to repopulate the root.
3. Bone Grafts and Scaffolds: Autografts (patient's own bone: osteogenic), Allografts (freeze-dried allogenic human bone: osteoinductive), Xenografts (deproteinized bovine bone mineral [DBBM / Bio-Oss]: osteoconductive matrix), and Alloplasts (synthetic beta-tricalcium phosphate). They provide mechanical space maintenance preventing flap collapse.

Choosing Between Resective and Regenerative Surgery

The decision is driven by the morphology of the defect, and this is what SBAs test. Regeneration — with guided tissue regeneration membranes, enamel matrix derivative, or bone grafts — is predictable in narrow, deep, contained intrabony defects with two or three remaining bony walls and in Class II mandibular furcations, where the surrounding walls provide space maintenance and a source of progenitor cells. Resective surgery — apically repositioned flaps, osseous recontouring, root resection, tunnelling — suits shallow, wide, one-walled defects and horizontal bone loss, where regeneration is unpredictable, and is used to achieve a maintainable architecture.

The prerequisites for any periodontal surgery are examinable and absolute: excellent plaque control demonstrated over time, smoking cessation or at least a frank discussion of its effect on outcomes, control of diabetes, and completion of non-surgical therapy with adequate healing time. Operating on a patient with poor plaque control produces worse results than not operating, and recommending surgery in that situation is a wrong answer.

Crown Lengthening and Restorative Interfaces

Where a restorative margin would encroach on the supracrestal attachment, surgical crown lengthening or orthodontic extrusion restores the biological dimension. The accepted requirement is at least 2 mm of supracrestal attachment plus an adequate sulcus, so approximately 3 mm of sound tooth structure coronal to the bone crest is created, and the tissues are allowed to mature — conventionally three months, longer in the aesthetic zone — before definitive impressions.