Periodontology: Gingiva Anatomy

• Periodontology is the study of the supporting structures of the teeth (periodontium) and diseases and conditions that affect them
• The periodontium consists of gingiva, cementum, periodontal ligament, and alveolar bone

Gingiva

• The gingiva is the part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of the teeth
• The function of the gingiva is to protect the underlying tissues from the oral environment
• Anatomically, it is divided into marginal, attached, and interdental gingiva

Marginal Gingiva

• The unattached, terminal edge or border of the gingiva surrounding the teeth in a collar-like fashion
• It is about 1 mm wide and forms the soft tissue wall of the gingival sulcus

Attached Gingiva

• Continuous with the marginal gingiva
• Firm, resilient, and tightly bound to the underlying periosteum of alveolar bone
• The width of the attached gingiva is an important clinical parameter
• It is widest in the incisor and molar regions and narrowest in the premolar regions

Interdental Gingiva

• Occupies the gingival embrasure, which is the interproximal space beneath the area of contact between two teeth
• It can be pyramidal or have a "col" shape
• The shape depends on the contact point of the adjacent teeth and the presence or absence of recession

Cementum

• A specialized calcified substance covering the root surfaces of teeth
• Provides attachment to the periodontal ligament fibers
• Cementum is avascular and receives its nutrients from the periodontal ligament

Periodontal Ligament (PDL)

• The fibrous connective tissue that surrounds and attaches the tooth roots to the alveolar bone
• Functions include:
  • Supportive: Attaches the tooth to the bone
  • Sensory: Provides tactile, pressure, and pain sensations
  • Nutritive: Supplies nutrients to the cementum and bone
  • Formative: Contains cells that can form cementum and bone
  • Resorptive: Can resorb bone and cementum
• The PDL is composed of collagen fibers, cells, and ground substance

Sharpey's Fibers

• The terminal portions of the principal fibers of the periodontal ligament
• Inserted into the cementum and alveolar bone

Cells of the PDL

• Fibroblasts: The most numerous cells in the PDL; responsible for collagen synthesis and degradation
• Cementoblasts: Produce cementum
• Osteoblasts: Produce bone
• Osteoclasts: Resorb bone
• Epithelial rests of Malassez: Remnants of Hertwig's epithelial root sheath; can potentially form cysts

Alveolar Bone

• The bone of the jaw that surrounds and supports the roots of the teeth
• Consists of:
  • Alveolar bone proper: Thin layer of bone that lines the tooth socket
  • Supporting alveolar bone: Consists of cortical plates and trabecular bone

Alveolar Bone Proper

• Contains numerous perforations, through which blood vessels, nerves, and lymphatics pass from the alveolar bone to the periodontal ligament
• Radiographically, it is termed the lamina dura

Periodontal Diseases

• Primarily inflammatory diseases affecting the periodontium
• Classified into:
  • Gingivitis: Inflammation of the gingiva
  • Periodontitis: Inflammation of the supporting tissues of the teeth, leading to attachment loss and bone loss

Gingivitis

• Characterized by:
  • Redness
  • Swelling
  • Bleeding on probing
• Usually caused by plaque accumulation
• Reversible with good oral hygiene

Periodontitis

• Characterized by:
  • Attachment loss
  • Bone loss
  • Pocket formation
  • Gingival inflammation
• Irreversible damage to the periodontium
• Can lead to tooth mobility and tooth loss

Classification of Periodontal Diseases and Conditions

• Periodontal diseases and conditions are classified into the following categories:
  • Gingival diseases
  • Periodontitis
  • Other conditions affecting the periodontium

Gingival Diseases

• Dental plaque-induced gingival diseases:
  • Gingivitis associated with dental plaque only
  • Gingival diseases modified by systemic factors
  • Gingival diseases modified by medications
  • Gingival diseases modified by malnutrition
• Non-plaque induced gingival lesions:
  • Gingival diseases of specific bacterial origin
  • Gingival diseases of viral origin
  • Gingival diseases of fungal origin
  • Gingival diseases of genetic origin
  • Gingival manifestations of systemic conditions
  • Traumatic lesions

Periodontitis

• Necrotizing periodontal diseases:
  • Necrotizing gingivitis (NG)
  • Necrotizing periodontitis (NP)
  • Necrotizing stomatitis
• Periodontitis as a manifestation of systemic diseases
• Periodontitis:
  • Stage I: Initial periodontitis
  • Stage II: Moderate periodontitis
  • Stage III: Severe periodontitis with potential for additional tooth loss
  • Stage IV: Severe periodontitis with potential for loss of the dentition
  • Extent and Distribution: Localized, Generalized, Molar-Incisor Pattern

Other Conditions Affecting the Periodontium

• Systemic diseases or conditions affecting the periodontal supporting tissues
• Periodontal abscesses
• Periodontitis associated with endodontic lesions
• Mucogingival deformities and conditions around teeth
• Traumatic occlusal forces
• Tooth- and prosthesis-related factors

Etiology of Periodontal Diseases

• Primary Etiology: Dental plaque (biofilm)
• Secondary Etiology: Factors that contribute to plaque accumulation or modify the host response

Dental Plaque

• A complex microbial community (biofilm) that adheres to the tooth surface
• Composed of bacteria, fungi, viruses, and protozoa
• Plaque formation involves:
  • Pellicle formation: A thin film of salivary glycoproteins that adheres to the tooth surface
  • Initial bacterial colonization: Attachment of early colonizers (e.g., Streptococcus)
  • Coaggregation: Attachment of other bacteria to the early colonizers
  • Biofilm maturation: Formation of a complex three-dimensional structure

Key Periodontal Pathogens

• Aggregatibacter actinomycetemcomitans
• Porphyromonas gingivalis
• Tannerella forsythia
• Treponema denticola

Host Response

• The host immune response plays a critical role in the pathogenesis of periodontitis
• The host response aims to eliminate the bacteria and prevent tissue destruction, but can also contribute to tissue damage

Inflammatory Mediators

• Cytokines (e.g., IL-1, TNF-α, IL-6)
• Prostaglandins (e.g., PGE2)
• Matrix metalloproteinases (MMPs)

Risk Factors for Periodontal Disease

• Smoking: Impairs wound healing and reduces the immune response
• Diabetes: Increases the risk of periodontal disease and impairs wound healing
• Genetic factors: Some individuals are more susceptible to periodontal disease due to genetic factors
• Stress: Can affect the immune response
• Medications: Some medications can cause gingival enlargement or dry mouth, increasing the risk of periodontal disease

Diagnosis of Periodontal Diseases

• Medical and dental history
• Clinical examination:
  • Visual examination: Assessing gingival inflammation, recession, and furcation involvement
  • Probing depth: Measuring the distance from the gingival margin to the base of the periodontal pocket
  • Clinical attachment loss (CAL): Measuring the distance from the cementoenamel junction (CEJ) to the base of the periodontal pocket
  • Bleeding on probing (BOP): Assessing gingival inflammation
  • Tooth mobility: Assessing the degree of tooth movement
  • Furcation involvement: Assessing bone loss in the furcation area of multirooted teeth
• Radiographic examination: Assessing bone loss

Periodontal Probing

• A calibrated instrument to measure the depth of the gingival sulcus or periodontal pocket
• Used to assess the level of attachment loss

Clinical Attachment Loss (CAL)

• The distance from the cementoenamel junction (CEJ) to the base of the periodontal pocket
• A more accurate measurement of periodontal destruction compared to probing depth
• Can be determined from radiographs, but most accurately through clinical measurement using a periodontal probe

Radiographic Examination

• Panoramic radiographs: Provide a general overview of the dentition and surrounding structures
• Periapical radiographs: Provide detailed images of individual teeth and surrounding bone
• Bitewing radiographs: Used to detect interproximal caries and assess alveolar bone height
• Cone-beam computed tomography (CBCT): Provides three-dimensional images of the teeth and surrounding bone

Treatment of Periodontal Diseases

• Goals of periodontal treatment:
  • Control inflammation
  • Eliminate infection
  • Arrest disease progression
  • Preserve teeth and supporting tissues
  • Improve esthetics and function
• Treatment modalities:
  • Non-surgical periodontal therapy
  • Surgical periodontal therapy
  • Maintenance therapy

Non-Surgical Periodontal Therapy

• Scaling and root planing (SRP): Removal of plaque and calculus from tooth surfaces and root surfaces
• Plaque control instructions: Teaching patients how to effectively remove plaque at home
• Adjunctive therapies:
  • Antimicrobial agents (e.g., chlorhexidine mouthwash, antibiotics)
  • Local delivery of antimicrobials (e.g., antibiotics placed directly into the periodontal pocket)

Scaling and Root Planing (SRP)

• Removal of plaque, calculus, and altered cementum from the tooth surfaces
• Aims to create a biologically compatible root surface

Surgical Periodontal Therapy

• Used to access and treat areas that are difficult to reach with non-surgical therapy
• Examples of surgical procedures:
  • Flap surgery: Incising the gingiva to gain access to the root surfaces and underlying bone
  • Guided tissue regeneration (GTR): Using barrier membranes to prevent epithelial cells from migrating into the wound area, allowing periodontal ligament cells and bone cells to regenerate
  • Bone grafting: Placing bone or bone substitutes into bone defects to stimulate bone regeneration
  • Gingivectomy: Removal of excess gingival tissue
  • Gingivoplasty: Reshaping the gingiva
  • Mucogingival surgery: Procedures to correct mucogingival defects, such as recession

Guided Tissue Regeneration (GTR)

• Using barrier membranes to prevent epithelial cells from migrating into the wound area
• Promotes selective repopulation of the root surface with cells from the periodontal ligament and bone

Periodontal Maintenance Therapy

• Continuing care provided after active periodontal treatment
• Goals of maintenance therapy:
  • Prevent recurrence of disease
  • Monitor periodontal health
  • Provide ongoing plaque control instructions
• Typically involves periodic examinations, scaling and root planing, and plaque control reinforcement

An overview of periodontology, focusing on the anatomy of the gingiva. This includes descriptions of the marginal, attached, and interdental gingiva, as well as their functions in protecting the underlying tissues of the mouth.