Guided bone and tissue regeneration (dentistry)

Guided bone and tissue regeneration (GBR/GTR) in dentistry is a surgical procedure that utilizes barrier membranes to direct the growth of new bone and soft tissues at sites with insufficient volume or defects. It is primarily employed to regenerate lost periodontal support, enhance bone volume for dental implant placement, and treat other bony defects in the oral cavity.

The underlying principle of GBR/GTR is to create a protected space where cells with regenerative potential (osteoblasts, fibroblasts, cementoblasts, and periodontal ligament cells) can proliferate and differentiate without interference from faster-growing epithelial cells and connective tissue cells that might otherwise populate the defect and inhibit bone regeneration.

The procedure typically involves the following steps:

1. Site Preparation: The surgical site is thoroughly cleaned and debrided to remove any infected or necrotic tissue. Root planning may be performed on adjacent teeth to remove plaque and calculus.

2. Membrane Placement: A biocompatible membrane, either resorbable or non-resorbable, is carefully positioned to cover the bone defect. The membrane acts as a barrier, preventing soft tissue cells from invading the space intended for bone regeneration.

3. Grafting Material (Optional): A bone grafting material, such as autograft (bone from the patient), allograft (bone from a cadaver), xenograft (bone from an animal source), or synthetic bone substitutes, may be placed within the defect to provide a scaffold for new bone formation and to maintain the space under the membrane.

4. Membrane Fixation (If applicable): Non-resorbable membranes typically require fixation with tacks or screws to prevent movement and ensure proper space maintenance.

5. Wound Closure: The soft tissues are carefully sutured to achieve primary closure, completely covering the membrane and graft material.

6. Healing Phase: A healing period of several months is required to allow for bone and tissue regeneration.

7. Second-Stage Surgery (If applicable): If a non-resorbable membrane was used, a second surgery is necessary to remove it.

GBR/GTR techniques are used in a variety of dental applications, including:

• Treatment of Periodontal Defects: Regenerating bone and periodontal ligament lost due to periodontitis.
• Ridge Augmentation: Increasing the width or height of the alveolar ridge to provide adequate bone volume for dental implant placement.
• Sinus Lifts: Elevating the sinus membrane to create space for bone grafting in the posterior maxilla.
• Socket Preservation: Filling the extraction socket with bone grafting material and covering it with a membrane to prevent bone loss after tooth extraction.
• Peri-implant Defects: Repairing bone defects around dental implants.

The success of GBR/GTR depends on several factors, including the size and configuration of the defect, the type of membrane and grafting material used, the patient's overall health, and the surgeon's skill and experience. Post-operative care and patient compliance with oral hygiene instructions are also crucial for successful outcomes.