NEET MDS Lessons
Periodontology
- Chlorhexidine:
- Minimum: 0.12%; Optimum: 0.2%.
- Chip degrades in 7 – 10 days.
- Floss & Brushes:
- Preferred floss: Unwaxed thin.
- Floss length: 12 – 18 inches.
- Toothbrush: 2 – 4 rows, 5 – 12 tufts per row.
- Soft bristle diameter: 0.2 mm.
- Powered Brushes: Invented in 1939; use oscillating/rotating motion.
- Fones Technique: Circular brushing method.
- Antiplaque Agents:
- Bisbiguanides: 2nd generation.
- Pyrophosphate: Inhibits calculus formation.
Laser Classifications
Hard Tissue Lasers
- Er:YAG and Er:YSGG: Highest water absorption coefficients
- Applications: Calculus removal, root surface modification, bone surgery
Soft Tissue Applications
- CO2 Laser: Excellent for soft tissue procedures
- Diode Lasers: Hemostasis and bacterial reduction
Microsurgery Principles
Wound Approximation
- Technique: Butt joint approximation for optimal healing
- Instrumentation: Instruments weighing ≤15-20g for precision
Bone grafting is a critical procedure in periodontal and dental surgery, aimed at restoring lost bone and supporting the regeneration of periodontal tissues. Various materials can be used for bone grafting, each with unique properties and applications.
A. Osseous Coagulum
- Composition: Osseous coagulum is a mixture of bone dust and blood. It is created using small particles ground from cortical bone.
- Sources: Bone dust can be obtained from various
anatomical sites, including:
- Lingual ridge of the mandible
- Exostoses
- Edentulous ridges
- Bone distal to terminal teeth
- Application: This material is used in periodontal surgery to promote healing and regeneration of bone in areas affected by periodontal disease.
B. Bioactive Glass
- Composition: Bioactive glass consists of sodium and calcium salts, phosphates, and silicon dioxide.
- Function: It promotes bone regeneration by forming a bond with surrounding bone and stimulating cellular activity.
C. HTR Polymer
- Composition: HTR Polymer is a non-resorbable, microporous, biocompatible composite made from polymethyl methacrylate (PMMA) and polyhydroxymethacrylate.
- Application: This material is used in various dental and periodontal applications due to its biocompatibility and structural properties.
D. Other Bone Graft Materials
- Sclera: Used as a graft material due to its collagen content and biocompatibility.
- Cartilage: Can be used in certain grafting procedures, particularly in reconstructive surgery.
- Plaster of Paris: Occasionally used in bone grafting, though less common due to its non-biological nature.
- Calcium Phosphate Biomaterials: These materials are osteoconductive and promote bone healing.
- Coral-Derived Materials: Natural coral can be processed to create a scaffold for bone regeneration.
- 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.
Localized Aggressive Periodontitis and Necrotizing Ulcerative Gingivitis
Localized Aggressive Periodontitis (LAP)
Localized aggressive periodontitis, previously known as localized juvenile periodontitis, is characterized by specific microbial profiles and clinical features.
- Microbiota Composition:
- The microbiota associated with LAP is predominantly composed of:
- Gram-Negative, Capnophilic, and Anaerobic Rods.
- Key Organisms:
- Actinobacillus actinomycetemcomitans: The main organism involved in LAP.
- Other significant organisms include:
- Porphyromonas gingivalis
- Eikenella corrodens
- Campylobacter rectus
- Bacteroides capillus
- Spirochetes (various species).
- Viral Associations:
- Herpes viruses, including Epstein-Barr Virus-1 (EBV-1) and Human Cytomegalovirus (HCMV), have also been associated with LAP.
- The microbiota associated with LAP is predominantly composed of:
Necrotizing Ulcerative Gingivitis (NUG)
- Microbial Profile:
- NUG is characterized by high levels of:
- Prevotella intermedia
- Spirochetes (various species).
- NUG is characterized by high levels of:
- Clinical Features:
- NUG presents with necrosis of the gingival tissue, pain, and ulceration, often accompanied by systemic symptoms.
Microbial Shifts in Periodontal Disease
When comparing the microbiota across different states of periodontal health, a distinct microbial shift can be identified as the disease progresses from health to gingivitis to periodontitis:
-
From Gram-Positive to Gram-Negative:
- Healthy gingival sites are predominantly colonized by gram-positive bacteria, while diseased sites show an increase in gram-negative bacteria.
-
From Cocci to Rods (and Later to Spirochetes):
- In health, cocci (spherical bacteria) are prevalent. As the disease progresses, there is a shift towards rod-shaped bacteria, and in advanced stages, spirochetes become more prominent.
-
From Non-Motile to Motile Organisms:
- Healthy sites are often dominated by non-motile bacteria, while motile organisms increase in number as periodontal disease develops.
-
From Facultative Anaerobes to Obligate Anaerobes:
- In health, facultative anaerobes (which can survive with or without oxygen) are common. In contrast, obligate anaerobes (which thrive in the absence of oxygen) become more prevalent in periodontal disease.
-
From Fermenting to Proteolytic Species:
- The microbial community shifts from fermentative bacteria, which primarily metabolize carbohydrates, to proteolytic species that break down proteins, contributing to tissue destruction and inflammation.
Trauma from Occlusion
Trauma from occlusion refers to the injury sustained by periodontal tissues when occlusal forces exceed their adaptive capacity.
1. Trauma from Occlusion
- This term describes the injury that occurs to periodontal tissues when the forces exerted during occlusion (the contact between opposing teeth) exceed the ability of those tissues to adapt.
- Traumatic Occlusion: An occlusion that produces such injury is referred to as a traumatic occlusion. This can result from various factors, including malocclusion, excessive occlusal forces, or parafunctional habits (e.g., bruxism).
2. Clinical Signs of Trauma to the Periodontium
The most common clinical sign of trauma to the periodontium is:
- Increased Tooth Mobility: As the periodontal tissues are subjected to excessive forces, they may become compromised, leading to increased mobility of the affected teeth. This is often one of the first observable signs of trauma from occlusion.
3. Radiographic Signs of Trauma from Occlusion
Radiographic examination can reveal several signs indicative of trauma from occlusion:
-
Increased Width of Periodontal Space:
- The periodontal ligament space may appear wider on radiographs due to the increased forces acting on the tooth, leading to a loss of attachment and bone support.
-
Vertical Destruction of Inter-Dental Septum:
- Trauma from occlusion can lead to vertical bone loss in the inter-dental septa, which may be visible on radiographs as a reduction in bone height between adjacent teeth.
-
Radiolucency and Condensation of the Alveolar Bone:
- Areas of radiolucency may indicate bone loss, while areas of increased radiopacity (condensation) can suggest reactive changes in the bone due to the stress of occlusal forces.
-
Root Resorption:
- In severe cases, trauma from occlusion can lead to root resorption, which may be observed as a loss of root structure on radiographs.
Periodontal Diseases Associated with Neutrophil Disorders
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Acute Necrotizing Ulcerative Gingivitis (ANUG)
- Description: A severe form of gingivitis characterized by necrosis of the interdental papillae, pain, and foul odor.
- Association: Neutrophil dysfunction can exacerbate the severity of ANUG, leading to rapid tissue destruction.
-
Localized Juvenile Periodontitis
- Description: A form of periodontitis that typically affects adolescents and is characterized by localized bone loss around the permanent teeth.
- Association: Impaired neutrophil function contributes to the pathogenesis of this condition.
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Prepubertal Periodontitis
- Description: A rare form of periodontitis that occurs in children before puberty, leading to rapid attachment loss and bone destruction.
- Association: Neutrophil disorders can play a significant role in the development and progression of this disease.
-
Rapidly Progressive Periodontitis
- Description: A form of periodontitis characterized by rapid attachment loss and bone destruction, often occurring in young adults.
- Association: Neutrophil dysfunction may contribute to the aggressive nature of this disease.
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Refractory Periodontitis
- Description: A form of periodontitis that does not respond to conventional treatment and continues to progress despite therapy.
- Association: Neutrophil disorders may be implicated in the persistent nature of this condition.