NEET MDS Lessons
Periodontology
Platelet-Derived Growth Factor (PDGF)
Platelet-Derived Growth Factor (PDGF) is a crucial glycoprotein involved in various biological processes, particularly in wound healing and tissue repair. Understanding its role and mechanisms can provide insights into its applications in regenerative medicine and periodontal therapy.
Overview of PDGF
-
Definition:
- PDGF is a glycoprotein that plays a significant role in cell growth, proliferation, and differentiation.
-
Source:
- PDGF is carried in the alpha granules of platelets and is released during the process of blood clotting.
-
Discovery:
- It was one of the first growth factors to be described in scientific literature.
- Originally isolated from platelets, PDGF was found to exhibit mitogenic activity specifically in smooth muscle cells.
Functions of PDGF
-
Mitogenic Activity:
- PDGF stimulates the proliferation of various cell types, including:
- Smooth muscle cells
- Fibroblasts
- Endothelial cells
- This mitogenic activity is essential for tissue repair and regeneration.
- PDGF stimulates the proliferation of various cell types, including:
-
Role in Wound Healing:
- PDGF is released at the site of injury and plays a critical role in:
- Promoting cell migration to the wound site.
- Stimulating the formation of new blood vessels (angiogenesis).
- Enhancing the synthesis of extracellular matrix components, which are vital for tissue structure and integrity.
- PDGF is released at the site of injury and plays a critical role in:
-
Involvement in Periodontal Healing:
- In periodontal therapy, PDGF can be utilized to enhance healing in periodontal defects and promote regeneration of periodontal tissues.
- It has been studied for its potential in guided tissue regeneration (GTR) and in the treatment of periodontal disease.
Clinical Applications
-
Regenerative Medicine:
- PDGF is being explored in various regenerative medicine
applications, including:
- Bone regeneration
- Soft tissue healing
- Treatment of chronic wounds
- PDGF is being explored in various regenerative medicine
applications, including:
-
Periodontal Therapy:
- PDGF has been incorporated into certain periodontal treatment modalities to enhance healing and regeneration of periodontal tissues.
- It can be used in conjunction with graft materials to improve outcomes in periodontal surgery.
Periodontal Medications and Their Uses
Periodontal medications play a crucial role in the management of periodontal diseases, aiding in the treatment of infections, inflammation, and tissue regeneration. Understanding the various types of medications and their specific uses is essential for effective periodontal therapy.
Types of Periodontal Medications
-
Antibiotics:
- Uses:
- Used to treat bacterial infections associated with periodontal disease.
- Commonly prescribed antibiotics include amoxicillin, metronidazole, and doxycycline.
- Mechanism:
- They help reduce the bacterial load in periodontal pockets, promoting healing and reducing inflammation.
- Uses:
-
Antimicrobial Agents:
- Chlorhexidine:
- Uses: A topical antiseptic used as a mouth rinse to reduce plaque and gingivitis.
- Mechanism: It disrupts bacterial cell membranes and inhibits bacterial growth.
- Tetracycline:
- Uses: Can be used topically in periodontal pockets to reduce bacteria.
- Mechanism: Inhibits protein synthesis in bacteria, reducing their ability to cause infection.
- Chlorhexidine:
-
Anti-Inflammatory Medications:
- Non-Steroidal Anti-Inflammatory Drugs (NSAIDs):
- Uses: Used to manage pain and inflammation associated with periodontal disease.
- Examples: Ibuprofen and naproxen.
- Corticosteroids:
- Uses: May be used in severe cases to reduce inflammation.
- Mechanism: Suppress the immune response and reduce inflammation.
- Non-Steroidal Anti-Inflammatory Drugs (NSAIDs):
-
Local Delivery Systems:
- Doxycycline Gel (Atridox):
- Uses: A biodegradable gel that releases doxycycline directly into periodontal pockets.
- Mechanism: Provides localized antibiotic therapy to reduce bacteria and inflammation.
- Minocycline Microspheres (Arestin):
- Uses: A localized antibiotic treatment that is placed directly into periodontal pockets.
- Mechanism: Releases minocycline over time to combat infection.
- Doxycycline Gel (Atridox):
-
Regenerative Agents:
- Bone Grafts and Guided Tissue Regeneration (GTR) Materials:
- Uses: Used in surgical procedures to promote the regeneration of lost periodontal tissues.
- Mechanism: Provide a scaffold for new tissue growth and prevent the ingrowth of epithelium into the defect.
- Bone Grafts and Guided Tissue Regeneration (GTR) Materials:
-
Desensitizing Agents:
- Fluoride Varnishes:
- Uses: Applied to sensitive areas to reduce sensitivity and promote remineralization.
- Mechanism: Strengthens enamel and reduces sensitivity by occluding dentinal tubules.
- Fluoride Varnishes:
Clinical Significance of Periodontal Medications
-
Management of Periodontal Disease:
- Medications are essential in controlling infections and inflammation, which are critical for the successful treatment of periodontal diseases.
-
Adjunct to Non-Surgical Therapy:
- Periodontal medications can enhance the effectiveness of non-surgical treatments, such as scaling and root planing, by reducing bacterial load and inflammation.
-
Surgical Interventions:
- In surgical procedures, medications can aid in healing and regeneration, improving outcomes for patients undergoing periodontal surgery.
-
Patient Compliance:
- Educating patients about the importance of medications in their treatment plan can improve compliance and overall treatment success.
Flossing Technique
Flossing is an essential part of oral hygiene that helps remove plaque and food particles from between the teeth and along the gumline, areas that toothbrushes may not effectively clean. Proper flossing technique is crucial for maintaining gum health and preventing cavities.
Flossing Technique
-
Preparation:
- Length of Floss: Take 12 to 18 inches of dental floss. This length allows for adequate maneuverability and ensures that you can use a clean section of floss for each tooth.
- Grasping the Floss: Hold the floss taut between your hands, leaving a couple of inches of floss between your fingers. This tension helps control the floss as you maneuver it between your teeth.
-
Inserting the Floss:
- Slip Between Teeth: Gently slide the floss between your teeth. Be careful not to snap the floss, as this can cause trauma to the gums.
- Positioning: Insert the floss into the area between your teeth and gums as far as it will comfortably go, ensuring that you reach the gumline.
-
Flossing Motion:
- Vertical Strokes: Use 8 to 10 vertical strokes with the floss to dislodge food particles and plaque. Move the floss up and down against the sides of each tooth, making sure to clean both the front and back surfaces.
- C-Shaped Motion: For optimal cleaning, wrap the floss around the tooth in a C-shape and gently slide it beneath the gumline.
-
Frequency:
- Daily Flossing: Aim to floss at least once a day. Consistency is key to maintaining good oral hygiene.
- Best Time to Floss: The most important time to floss is before going to bed, as this helps remove debris and plaque that can accumulate throughout the day.
-
Flossing and Brushing:
- Order of Operations: Flossing can be done either before or after brushing your teeth. Both methods are effective, so choose the one that fits best into your routine.
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.
Microbes in Periodontics
Bacteria Associated with Periodontal Health
-
Primary Species:
- Gram-Positive Facultative Bacteria:
- Streptococcus:
- S. sanguis
- S. mitis
- A. viscosus
- A. naeslundii
- Actinomyces:
- Beneficial for maintaining periodontal health.
- Streptococcus:
- Gram-Positive Facultative Bacteria:
-
Protective or Beneficial Bacteria:
- Key Species:
- S. sanguis
- Veillonella parvula
- Corynebacterium ochracea
- Characteristics:
- Found in higher numbers at inactive periodontal sites (no attachment loss).
- Low numbers at sites with active periodontal destruction.
- Prevent colonization of pathogenic microorganisms (e.g., S. sanguis produces peroxide).
- Key Species:
-
Clinical Relevance:
- High levels of C. ochracea and S. sanguis are associated with greater attachment gain post-therapy.
Microbiology of Chronic Plaque-Induced Gingivitis
-
Composition:
- Roughly equal proportions of:
- Gram-Positive: 56%
- Gram-Negative: 44%
- Facultative: 59%
- Anaerobic: 41%
- Roughly equal proportions of:
-
Predominant Gram-Positive Species:
- S. sanguis
- S. mitis
- S. intermedius
- S. oralis
- A. viscosus
- A. naeslundii
- Peptostreptococcus micros
-
Predominant Gram-Negative Species:
- Fusobacterium nucleatum
- Porphyromonas intermedia
- Veillonella parvula
- Haemophilus spp.
- Capnocytophaga spp.
- Campylobacter spp.
-
Pregnancy-Associated Gingivitis:
- Increased levels of steroid hormones and P. intermedia.
Chronic Periodontitis
-
Key Microbial Species:
- High levels of:
- Porphyromonas gingivalis
- Bacteroides forsythus
- Porphyromonas intermedia
- Campylobacter rectus
- Eikenella corrodens
- Fusobacterium nucleatum
- Actinobacillus actinomycetemcomitans
- Peptostreptococcus micros
- Treponema spp.
- Eubacterium spp.
- High levels of:
-
Pathogenic Mechanisms:
- P. gingivalis and A. actinomycetemcomitans can invade host tissue cells.
- Viruses such as Epstein-Barr Virus-1 (EBV-1) and human cytomegalovirus (HCMV) may contribute to bone loss.
Localized Aggressive Periodontitis
- Microbiota Characteristics:
- Predominantly gram-negative, capnophilic, and anaerobic rods.
- Almost all localized juvenile periodontitis (LJP) sites harbor A. actinomycetemcomitans, which can comprise up to 90% of the total cultivable microbiota.
Some important points about the periodontal pocket :
·Soft tissue of pocket wall shows both proliferative & degenerative changes
·Most severe degenerative changes are seen on the lateral wall of pocket
·Plasma cells are the predominant infiltrate (80%). Others include lymphocytes &
a scattering of PMNs
·Height of junctional epithelium shortened to only 50-100µm
·Severity of degenerative changes is not linked to pocket depth
·Junctional epithelium starts to lose attachment to tooth when PMN infiltration
in junctional epithelium increases above 60%.
Influence of Host Response on Periodontal Disease
The host response plays a critical role in the progression and management of periodontal disease. Various host factors influence bacterial colonization, invasion, tissue destruction, and healing processes. Understanding these interactions is essential for developing effective treatment strategies.
Aspects of Periodontal Disease and Host Factors
-
Bacterial Colonization:
- Host Factor: Antibody C in crevicular fluid.
- Mechanism:
- Antibody C inhibits the adherence and coaggregation of bacteria in the subgingival environment.
- This action potentially reduces bacterial numbers by promoting lysis (destruction of bacterial cells).
- Implication: A robust antibody response can help control the initial colonization of pathogenic bacteria, thereby influencing the onset of periodontal disease.
-
Bacterial Invasion:
- Host Factor: Antibody C-mediated lysis and neutrophil activity.
- Mechanism:
- Antibody C-mediated lysis reduces bacterial counts in the periodontal tissues.
- Neutrophils, through processes such as chemotaxis (movement towards chemical signals), phagocytosis (engulfing and digesting bacteria), and lysis, further reduce bacterial counts.
- Implication: An effective neutrophil response is crucial for controlling bacterial invasion and preventing the progression of periodontal disease.
-
Tissue Destruction:
- Host Factors: Antibody-mediated hypersensitivity and cell-mediated immune responses.
- Mechanism:
- Activation of tissue factors, such as collagenase, leads to the breakdown of connective tissue and periodontal structures.
- The immune response can inadvertently contribute to tissue destruction, as inflammatory mediators can damage host tissues.
- Implication: While the immune response is essential for fighting infection, it can also lead to collateral damage in periodontal tissues, exacerbating disease progression.
-
Healing and Fibrosis:
- Host Factors: Lymphocytes and macrophage-produced chemotactic factors.
- Mechanism:
- Lymphocytes and macrophages release chemotactic factors that attract fibroblasts to the site of injury.
- Fibroblasts are activated by specific factors, promoting tissue repair and fibrosis (the formation of excess connective tissue).
- Implication: A balanced immune response is necessary for effective healing and regeneration of periodontal tissues following inflammation.