NEET MDS Lessons
General Medicine
Periodontal Bone Grafts
Bone grafting is a critical procedure in periodontal surgery, aimed at restoring lost bone and supporting the regeneration of periodontal tissues.
1. Bone Blend
Bone blend is a mixture of cortical or cancellous bone that is procured using a trephine or rongeurs, placed in an amalgam capsule, and triturated to achieve a slushy osseous mass. This technique allows for the creation of smaller particle sizes, which enhances resorption and replacement with host bone.
Particle Size: The ideal particle size for bone blend is approximately 210 x 105 micrometers.
Rationale: Smaller particle sizes improve the chances of resorption and integration with the host bone, making the graft more effective.
2. Types of Periodontal Bone Grafts
A. Autogenous Grafts
Autogenous grafts are harvested from the patient’s own body, providing the best compatibility and healing potential.
-
Cortical Bone Chips
- History: First used by Nabers and O'Leary in 1965.
- Characteristics: Composed of shavings of cortical bone removed during osteoplasty and ostectomy from intraoral sites.
- Challenges: Larger particle sizes can complicate placement and handling, and there is a potential for sequestration. This method has largely been replaced by autogenous osseous coagulum and bone blend.
-
Osseous Coagulum and Bone Blend
- Technique: Intraoral bone is obtained using high- or low-speed round burs and mixed with blood to form an osseous coagulum (Robinson, 1969).
- Advantages: Overcomes disadvantages of cortical bone chips, such as inability to aspirate during collection and variability in quality and quantity of collected bone.
- Applications: Used in various periodontal procedures to enhance healing and regeneration.
-
Intraoral Cancellous Bone and Marrow
- Sources: Healing bony wounds, extraction sockets, edentulous ridges, mandibular retromolar areas, and maxillary tuberosity.
- Applications: Provides a rich source of osteogenic cells and growth factors for bone regeneration.
-
Extraoral Cancellous Bone and Marrow
- Sources: Obtained from the anterior or posterior iliac crest.
- Advantages: Generally offers the greatest potential for new bone growth due to the abundance of cancellous bone and marrow.
B. Bone Allografts
Bone allografts are harvested from donors and can be classified into three main types:
-
Undermineralized Freeze-Dried Bone Allograft (FDBA)
- Introduction: Introduced in 1976 by Mellonig et al.
- Process: Freeze drying removes approximately 95% of the water from bone, preserving morphology, solubility, and chemical integrity while reducing antigenicity.
- Efficacy: FDBA combined with autogenous bone is more effective than FDBA alone, particularly in treating furcation involvements.
-
Demineralized (Decalcified) FDBA
- Mechanism: Demineralization enhances osteogenic potential by exposing bone morphogenetic proteins (BMPs) in the bone matrix.
- Osteoinduction vs. Osteoconduction: Demineralized grafts induce new bone formation (osteoinduction), while undermineralized allografts facilitate bone growth by providing a scaffold (osteoconduction).
-
Frozen Iliac Cancellous Bone and Marrow
- Usage: Used sparingly due to variability in outcomes and potential complications.
Comparison of Allografts and Alloplasts
- Clinical Outcomes: Both FDBA and DFDBA have been compared to porous particulate hydroxyapatite, showing little difference in post-treatment clinical parameters.
- Histological Healing: Grafts of DFDBA typically heal with regeneration of the periodontium, while synthetic bone grafts (alloplasts) heal by repair, which may not restore the original periodontal architecture.
- Drugs in GCF: Tetracycline, Metronidazole
- Probes:
- Conventional: Williams, Naber’s, CPITN
- Pressure-sensitive: Foster Miller
- Automated: Florida, Toronto
- CPITN: 0.5 mm tip; markings at 3.5, 5.5, 8.5, 11.5 mm
- Scaling & Curettage:
- Blade angulation: 45 – 90° (scaling); >90° (curettage)
- Curette sharpening: 100 – 110°
- Chisel scaler: Push motion
- Hoe scaler: Blade bent at 99°, used for ledges/rings
- Bone Defects:
- Most common: Osseous craters.
- Best graft success: Three-walled defects.
- Bone graft types:
- Autogenous cancellous: Most osteogenic.
- Xenograft: From different species.
- Osteoplasty: Recontouring without removing supporting bone.
- Osteotomy: Removes supporting bone.
- Implants:
- Minimum 5 mm from mental foramen.
- Blade implants: Linkow; Cylindrical: Schroeder.
- Micro-movement >150 µm: Fibrous tissue formation.
- Connective tissue near implant: No blood vessels, many fibroblasts.
- Probing: Use plastic probes; max force = 25 N.
- Florida probe tip: 0.4 mm.
Necrotizing Ulcerative Gingivitis (NUG)
Necrotizing Ulcerative Gingivitis (NUG), also known as Vincent's disease or trench mouth, is a severe form of periodontal disease characterized by the sudden onset of symptoms and specific clinical features.
Etiology and Predisposing Factors
- Sudden Onset: NUG is characterized by a rapid onset of symptoms, often following debilitating diseases or acute respiratory infections.
- Lifestyle Factors: Changes in living habits, such as prolonged work without adequate rest, poor nutrition, tobacco use, and psychological stress, are frequently noted in patient histories .
- Smoking: Smoking has been identified as a significant predisposing factor for NUG/NDP .
- Immune Compromise: Conditions that compromise the immune system, such as poor oral hygiene, smoking, and emotional stress, are major contributors to the development of NUG .
Clinical Presentation
- Symptoms: NUG presents with:
- Punched-out, crater-like depressions at the crest of interdental papillae.
- Marginal gingival involvement, with rare extension to attached gingiva and oral mucosa.
- Grey, pseudomembranous slough covering the lesions.
- Spontaneous bleeding upon slight stimulation of the gingiva.
- Fetid odor and increased salivation.
Microbiology
- Mixed Bacterial Infection: NUG is caused by a complex
of anaerobic bacteria, often referred to as the fusospirochetal complex,
which includes:
- Treponema vincentii
- Treponema denticola
- Treponema macrodentium
- Fusobacterium nucleatum
- Prevotella intermedia
- Porphyromonas gingivalis
Treatment
-
Control of Acute Phase:
- Clean the wound with an antibacterial agent.
- Irrigate the lesion with warm water and 5% vol/vol hydrogen peroxide.
- Prescribe oxygen-releasing mouthwash (e.g., hydrogen peroxide DPF, sodium perborate DPF) to be used thrice daily.
- Administer oral metronidazole for 3 to 5 days. If sensitive to metronidazole, prescribe penicillin; if sensitive to both, consider erythromycin or clindamycin.
- Use 2% chlorhexidine in select cases for a short duration.
-
Management of Residual Condition:
- Remove predisposing local factors (e.g., overhangs).
- Perform supra- and subgingival scaling.
- Consider gingivoplasty to correct any residual gingival deformities.
Stage 1: Initial Lesion
- 2 – 4 days after plaque accumulation
Stage 2: Early Lesion
- Timeline: 4 – 7 days after plaque accumulation
- T – lymphocyte dominance
Stage 3: Established Lesion
- Characteristic: Plasma cells and B – lymphocytes dominance
Bleeding on Probing (BOP)
- Appears earlier than visual signs
- Absence = good negative predictor of attachment loss
- Angulation vs Adaptation:
- Angulation: Angle between blade face and tooth surface.
- Adaptation: Relationship of blade’s working end to tooth surface.
- Curettes:
- Gracey: Blade offset at 60°.
- Universal: Blade angle at 90°.
- After Five: Extended shank by 3 mm; available in all Gracey numbers except 9 – 10.
- Mini Five: Blade half the length of conventional curette.
- Langer Curette: Gracey curette modified with universal blade angle.
- Scaling & Sharpening:
- Blade angulation for scaling: 45 – 90°; for curettage: >90°.
- Sharpening angle: 100 – 110°.
- Chisel scaler: Push motion; Hoe scaler: Blade bent at 99°.
- Sickle scaler blade-to-shank angle: 70°.
- Microsurgery:
- Instrument weight: 15 – 20 g.
- Principles: Butt joint approximation, enhanced motor skills, minimal trauma.
- Suturing:
- Needle entry: Right angle, 2 – 3 mm from incision.
- Biological Width: Composed of connective tissue (1.07 mm) and epithelial attachment (0.97 mm).
- Gingival Sulcus: Shallower in primary teeth; probing depth is 1 – 2 mm.
- Gingival Blood Supply: Includes supraperiosteal arterioles, periodontal ligament vessels, and interdental septa arterioles.
- GCF (Gingival Crevicular Fluid): Can be exudative or transudative; becomes exudative during inflammation.
Pediatric & Pregnancy Considerations
- Safest Dental Care Period: Early second trimester.
- Pregnancy Gingivitis: Characterized by pronounced bleeding.
- Puberty-Related Changes: Increase in P. intermedia and Capnocytophaga.