30.2 Surgical Flap Design, Bone Removal and Suturing

2. Surgical Exodontia: Flap Design, Bone Removal & Suturing

When a tooth cannot be delivered using closed forceps or elevator mechanics, an open surgical approach is required.

Surgical Exodontia Protocol Architecture
  │
  ├── Mucoperiosteal Flap Design
  │     ├── Base broader than free margin (Preserves axial blood supply)
  │     ├── Incisions placed over sound bone (≥ 4–5 mm from osteotomy margin)
  │     └── Full-thickness reflection (Subperiosteal dissection to bone)
  │
  ├── Surgical Bone Removal & Sectioning
  │     ├── Surgical straight handpiece with sterile saline irrigation (No air-turbine!)
  │     ├── Continuous cooling (Maintains bone temperature < 47°C to prevent necrosis)
  │     └── Buccal and distal guttering + Tooth sectioning (Decapitation / Hemisection)
  │
  └── Wound Closure & Suturing
        ├── Tension-free approximation over intact bone
        ├── Interrupted vs Horizontal Mattress sutures
        └── Resorbable (Vicryl/Monocryl) vs Non-resorbable (Silk) selection

Mucoperiosteal Flap Design Principles

A well-designed flap provides adequate surgical access while preserving tissue vascularity and promoting uncomplicated primary healing:

1. Broad Vascular Base: The base of the flap must be wider than the coronal margin to ensure uninterrupted axial blood supply from underlying and peripheral vessels, preventing ischemic flap necrosis.
2. Margins on Sound Bone: All surgical incision lines must lie on intact, healthy bone at least 4 to 5 mm away from the anticipated edge of bone removal. Suture lines that collapse into an empty bone defect break down, causing wound dehiscence.
3. Full-Thickness Reflection: The incision must penetrate cleanly through oral mucosa, submucosa, and periosteum down to cortical bone in a single stroke. Reflection must be strictly subperiosteal (using a Howarth's or Mitchell's periosteal elevator) to minimize haemorrhage and preserve periosteal osteogenic capacity.
4. Relieving Incisions: Releasing incisions must be placed at the line angles of teeth (mesiobuccal or distobuccal line angles), never directly over the mid-buccal root surface (which causes severe gingival recession) or through an interdental papilla (which leads to blunt, clefted papillae).
5. Flap Configurations:
   • Two-Sided (Triangular) Flap: A horizontal crevicular incision plus a single anterior vertical relieving incision. Provides excellent access with minimal surgical trauma; preferred for most surgical extractions and root removals.
   • Three-Sided (Trapezoidal) Flap: Crevicular incision plus two diverging vertical releasing incisions. Provides maximum apical access but carries increased risk of swelling and scarring.
   • Envelope Flap: Crevicular incision extending two teeth anteriorly and one tooth posteriorly without vertical relieving incisions. Heals rapidly with zero vertical scarring, but provides limited apical visibility and requires excessive tissue retraction tension.

Surgical Bone Removal & Tooth Sectioning

• Equipment: Must use a dedicated surgical straight handpiece with a sterile tungsten carbide round or fissure bur (e.g. Lindemann bur).
• CRITICAL SAFETY WARNING: Prohibition of Air-Turbine Handpieces: High-speed air-turbine dental handpieces must NEVER be used in oral surgery. Pressurized exhaust air forced into open surgical wounds enters facial fascial planes, causing surgical subcutaneous emphysema, fascial space infection, and potentially fatal air embolism into the mediastinum or systemic circulation.
• Continuous Saline Irrigation: Bone cutting must be performed under copious, continuous irrigation with cold, sterile isotonic saline ($0.9%\text{ NaCl}$). Thermal Osteonecrosis: Bone cells undergo irreversible cellular death when heated above 47°C for 1 minute, leading to delayed healing, avascular bone necrosis, and painful sequestrum formation.
• Bone Guttering: A narrow trough of buccal and distal cortical bone is removed around the tooth crown to create a point of application for elevators.
• Tooth Sectioning: Multi-rooted teeth are sectioned into individual single-rooted units along anatomical furcations (e.g. dividing lower molars bucco-lingually into mesial and distal halves; dividing upper molars into two buccal roots and one palatal root) to allow separate delivery along independent paths of withdrawal.

Suturing Techniques & Materials

• Simple Interrupted Sutures: The standard technique in oral surgery; each suture is independent, ensuring that failure of one knot does not compromise the entire wound closure.
• Horizontal Mattress Sutures: Placed across an extraction socket or flap margin; provides outstanding wound edge eversion and exerts localized compression for haemostasis.
• Suture Materials:
  • Resorbable: Polyglactin 910 (Vicryl): Braided synthetic suture, maintains tensile strength for 2 to 3 weeks, resorbs by non-enzymatic hydrolysis within 56 to 70 days. Poliglecaprone 25 (Monocryl): Monofilament, smooth passage, low tissue drag, resorbs within 90 to 120 days.
  • Non-resorbable: Braided Black Silk: Exceptional handling characteristics and knot security; however, multifilament silk wicks oral fluids and plaque, provoking mild tissue inflammation; must be removed at 7 days.

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Postoperative Instructions and Follow-Up

Surgical exodontia is incomplete without instructions, and they are examined because they prevent the commonest complications. The patient is advised to bite on a gauze pack for a stated period, to avoid rinsing for the first 24 hours and then to use warm saline rinses, to avoid smoking, alcohol, strenuous exercise and hot food on the day, to take regular analgesia before the anaesthetic wears off, and to be given clear contact details for postoperative bleeding or swelling. They must be warned that a degree of swelling, trismus and bruising is expected after surgical removal and given a realistic timescale for resolution.