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Periodontology

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.
  • 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).
  • 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%
  • 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.
  • 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.

Classification of Periodontal Pockets

Periodontal pockets are an important aspect of periodontal disease, reflecting the health of the supporting structures of the teeth. Understanding the classification of these pockets is essential for diagnosis, treatment planning, and management of periodontal conditions.

Classification of Pockets

  1. Gingival Pocket:

    • Also Known As: Pseudo-pocket.
    • Formation:
      • Formed by gingival enlargement without destruction of the underlying periodontal tissues.
      • The sulcus is deepened due to the increased bulk of the gingiva.
    • Characteristics:
      • There is no destruction of the supporting periodontal tissues.
      • Typically associated with conditions such as gingival hyperplasia or inflammation.
  2. Periodontal Pocket:

    • Definition: A pocket that results in the destruction of the supporting periodontal tissues, leading to the loosening and potential exfoliation of teeth.
    • Classification Based on Location:
      • Suprabony Pocket:
        • The base of the pocket is coronal to the alveolar bone.
        • The pattern of bone destruction is horizontal.
        • The transseptal fibers are arranged horizontally in the space between the base of the pocket and the alveolar bone.
      • Infrabony Pocket:
        • The base of the pocket is apical to the alveolar bone, meaning the pocket wall lies between the bone and the tooth.
        • The pattern of bone destruction is vertical.
        • The transseptal fibers are oblique rather than horizontal.

Classification of Periodontal Pockets

  1. Suprabony Pocket (Supracrestal or Supraalveolar):

    • Location: Base of the pocket is coronal to the alveolar bone.
    • Bone Destruction: Horizontal pattern of bone loss.
    • Transseptal Fibers: Arranged horizontally.
  2. Infrabony Pocket (Intrabony, Subcrestal, or Intraalveolar):

    • Location: Base of the pocket is apical to the alveolar bone.
    • Bone Destruction: Vertical pattern of bone loss.
    • Transseptal Fibers: Arranged obliquely.

Classification of Pockets According to Involved Tooth Surfaces

  1. Simple Pocket:

    • Definition: Involves only one tooth surface.
    • Example: A pocket that is present only on the buccal surface of a tooth.
  2. Compound Pocket:

    • Definition: A pocket present on two or more surfaces of a tooth.
    • Example: A pocket that involves both the buccal and lingual surfaces.
  3. Spiral Pocket:

    • Definition: Originates on one tooth surface and twists around the tooth to involve one or more additional surfaces.
    • Example: A pocket that starts on the mesial surface and wraps around to the distal surface.

Theories Regarding the Mineralization of Dental Calculus

Dental calculus, or tartar, is a hard deposit that forms on teeth due to the mineralization of dental plaque. Understanding the mechanisms by which plaque becomes mineralized is essential for dental professionals in managing periodontal health. The theories regarding the mineralization of calculus can be categorized into two main mechanisms: mineral precipitation and the role of seeding agents.

1. Mineral Precipitation

Mineral precipitation involves the local rise in the saturation of calcium and phosphate ions, leading to the formation of calcium phosphate salts. This process can occur through several mechanisms:

A. Rise in pH

  • Mechanism: An increase in the pH of saliva can lead to the precipitation of calcium phosphate salts by lowering the precipitation constant.
  • Causes:
    • Loss of Carbon Dioxide: Bacterial activity in dental plaque can lead to the loss of CO2, resulting in an increase in pH.
    • Formation of Ammonia: The degradation of proteins by plaque bacteria can produce ammonia, further elevating the pH.

B. Colloidal Proteins

  • Mechanism: Colloidal proteins in saliva bind calcium and phosphate ions, maintaining a supersaturated solution with respect to calcium phosphate salts.
  • Process:
    • When saliva stagnates, these colloids can settle out, disrupting the supersaturated state and leading to the precipitation of calcium phosphate salts.

C. Enzymatic Activity

  • Phosphatase:
    • This enzyme, released from dental plaque, desquamated epithelial cells, or bacteria, hydrolyzes organic phosphates in saliva, increasing the concentration of free phosphate ions and promoting mineralization.
  • Esterase:
    • Present in cocci, filamentous organisms, leukocytes, macrophages, and desquamated epithelial cells, esterase can hydrolyze fatty esters into free fatty acids.
    • These fatty acids can form soaps with calcium and magnesium, which are subsequently converted into less-soluble calcium phosphate salts, facilitating calcification.

2. Seeding Agents and Heterogeneous Nucleation

The second theory posits that seeding agents induce small foci of calcification that enlarge and coalesce to form a calcified mass. This concept is often referred to as the epitactic concept or heterogeneous nucleation.

A. Role of Seeding Agents

  • Unknown Agents: The specific seeding agents involved in calculus formation are not fully understood, but it is believed that the intercellular matrix of plaque plays a significant role.
  • Carbohydrate-Protein Complexes:
    • These complexes may initiate calcification by chelating calcium from saliva and binding it to form nuclei that promote the deposition of minerals.

Clinical Implications

  1. Understanding Calculus Formation:

    • Knowledge of the mechanisms behind calculus mineralization can help dental professionals develop effective strategies for preventing and managing calculus formation.
  2. Preventive Measures:

    • Maintaining good oral hygiene practices can help reduce plaque accumulation and the conditions that favor mineralization, such as stagnation of saliva and elevated pH.
  3. Treatment Approaches:

    • Understanding the role of enzymes and proteins in calculus formation may lead to the development of therapeutic agents that inhibit mineralization or promote the dissolution of existing calculus.
  4. Research Directions:

    • Further research into the specific seeding agents and the biochemical processes involved in calculus formation may provide new insights into preventing and treating periodontal disease.

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.

Necrotizing Ulcerative Gingivitis (NUG)

  • Microbial Profile:
    • NUG is characterized by high levels of:
      • Prevotella intermedia
      • Spirochetes (various species).
  • 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:

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.

Dental Plaque

Dental plaque is a biofilm that forms on the surfaces of teeth and is composed of a diverse community of microorganisms. The development of dental plaque occurs in stages, beginning with primary colonizers and progressing to secondary colonization and plaque maturation.

Primary Colonizers

  • Timeframe:
    • Acquired within a few hours after tooth cleaning or exposure.
  • Characteristics:
    • Predominantly gram-positive facultative microbes.
  • Key Species:
    • Actinomyces viscosus
    • Streptococcus sanguis
  • Adhesion Mechanism:
    • Primary colonizers adhere to the tooth surface through specific adhesins.
    • For example, A. viscosus possesses fimbriae that bind to proline-rich proteins in the dental pellicle, facilitating initial attachment.

Secondary Colonization and Plaque Maturation

  • Microbial Composition:
    • As plaque matures, it becomes predominantly populated by gram-negative anaerobic microorganisms.
  • Key Species:
    • Prevotella intermedia
    • Prevotella loescheii
    • Capnocytophaga spp.
    • Fusobacterium nucleatum
    • Porphyromonas gingivalis
  • Coaggregation:
    • Coaggregation refers to the ability of different species and genera of plaque microorganisms to adhere to one another.
    • This process occurs primarily through highly specific stereochemical interactions of protein and carbohydrate molecules on cell surfaces, along with hydrophobic, electrostatic, and van der Waals forces.

Plaque Hypotheses

  1. Specific Plaque Hypothesis:

    • This hypothesis posits that only certain types of plaque are pathogenic.
    • The pathogenicity of plaque depends on the presence or increase of specific microorganisms.
    • It predicts that plaque harboring specific bacterial pathogens leads to periodontal disease due to the production of substances that mediate the destruction of host tissues.
  2. Nonspecific Plaque Hypothesis:

    • This hypothesis maintains that periodontal disease results from the overall activity of the entire plaque microflora.
    • It suggests that the elaboration of noxious products by the entire microbial community contributes to periodontal disease, rather than specific pathogens alone.

Sutures for Periodontal Flaps

Suturing is a critical aspect of periodontal surgery, particularly when managing periodontal flaps. The choice of suture material can significantly influence healing, tissue adaptation, and overall surgical outcomes.

1. Nonabsorbable Sutures

Nonabsorbable sutures are designed to remain in the tissue until they are manually removed. They are often used in situations where long-term support is needed.

A. Types of Nonabsorbable Sutures

  1. Silk (Braided)

    • Characteristics:
      • Excellent handling properties and knot security.
      • Provides good tissue approximation.
    • Applications: Commonly used in periodontal surgeries due to its ease of use and reliability.
  2. Nylon (Monofilament) (Ethilon)

    • Characteristics:
      • Strong and resistant to stretching.
      • Less tissue reactivity compared to silk.
    • Applications: Ideal for delicate tissues and areas requiring minimal tissue trauma.
  3. ePTFE (Monofilament) (Gore-Tex)

    • Characteristics:
      • Biocompatible and non-reactive.
      • Excellent tensile strength and flexibility.
    • Applications: Often used in guided tissue regeneration procedures and in areas where long-term support is needed.
  4. Polyester (Braided) (Ethibond)

    • Characteristics:
      • High tensile strength and good knot security.
      • Less pliable than silk.
    • Applications: Used in situations requiring strong sutures, such as in flap stabilization.

2. Absorbable Sutures

Absorbable sutures are designed to be broken down by the body over time, eliminating the need for removal. They are often used in periodontal surgeries where temporary support is sufficient.

A. Types of Absorbable Sutures

  1. Surgical Gut

    • Plain Gut (Monofilament)

      • Absorption Time: Approximately 30 days.
      • Characteristics: Made from sheep or cow intestines; provides good tensile strength initially but loses strength quickly.
      • Applications: Suitable for soft tissue approximation where rapid absorption is desired.
    • Chromic Gut (Monofilament)

      • Absorption Time: Approximately 45 to 60 days.
      • Characteristics: Treated with chromium salts to delay absorption; retains strength longer than plain gut.
      • Applications: Used in areas where a longer healing time is expected.
  2. Synthetic Absorbable Sutures

    • Polyglycolic Acid (Braided) (Vicryl, Ethicon)

      • Absorption Time: Approximately 16 to 20 days.
      • Characteristics: Provides good tensile strength and is absorbed predictably.
      • Applications: Commonly used in periodontal and oral surgeries due to its handling properties.
    • Dexon (Davis & Geck)

      • Characteristics: Similar to Vicryl; made from polyglycolic acid.
      • Applications: Used in soft tissue approximation and ligation.
    • Polyglycaprone (Monofilament) (Maxon)

      • Absorption Time: Similar to Vicryl.
      • Characteristics: Offers excellent tensile strength and is absorbed more slowly than other synthetic options.
      • Applications: Ideal for areas requiring longer support during healing.

PERIOTEST Device in Periodontal Assessment

The PERIOTEST device is a valuable tool used in dentistry to assess the mobility of teeth and the reaction of the periodontium to applied forces. This lecture covers the principles of the PERIOTEST device, its measurement scale, and its clinical significance in evaluating periodontal health.

Function: The PERIOTEST device measures the reaction of the periodontium to a defined percussion force applied to the tooth. This is done using a tapping instrument that delivers a controlled force to the tooth.

Contact Time: The contact time between the tapping head and the tooth varies between 0.3 and 2 milliseconds. This duration is typically shorter for stable teeth compared to mobile teeth, allowing for a quick assessment of tooth stability.

PERIOTEST Scale

The PERIOTEST scale ranges from -8 to +50, with specific ranges indicating different levels of tooth mobility:

Readings Inference
-8 to 9 Clinically firm teeth
10 to 19 First distinguishable sign of movement
20 to 29 Crown deviates within 1 mm of its normal position
30 to 50 Mobility is readily observed

Clinical Significance

Assessment of Tooth Mobility:
The PERIOTEST device provides a quantitative measure of tooth mobility, which is essential for diagnosing periodontal disease and assessing the stability of teeth.

Correlation with Other Measurements:
The PERIOTEST values correlate well with:

  • Tooth Mobility Assessed with a Metric System: This allows for a standardized approach to measuring mobility, enhancing the reliability of assessments.

  • Degree of Periodontal Disease and Alveolar Bone Loss: Higher mobility readings often indicate more severe periodontal disease and greater loss of supporting bone, making the PERIOTEST a useful tool in monitoring disease progression.

Treatment Planning:
Understanding the mobility of teeth can aid in treatment planning, including decisions regarding periodontal therapy, splinting of mobile teeth, or extraction in cases of severe mobility.

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