DD - Perio Page 274- 344

Cellular Elements of Gingival Connective Tissue

• Fibroblasts: dominant cellular element, found between fiber bundles, of mesenchymal origin, and play a major role in development, maintenance, and repair of gingival connective tissue.
• Mast cells: numerous in the connective tissue of the oral mucosa and gingiva.
• Fixed macrophages and histiocytes: present in the gingival connective tissue as components of the mononuclear phagocyte system, derived from blood monocytes.
• Adipose cells and eosinophils: scarce in the lamina propria.
• Plasma cells and lymphocytes: found in small foci in the connective tissue near the base of the sulcus in clinically normal gingiva.

Blood Supply to the Gingiva

• Three sources:
  • Supraperiosteal arterioles: along the facial and lingual surfaces of the alveolar bone, extending capillaries to the sulcular epithelium and between the rete pegs of the external gingival surface.
  • Vessels of the PDL: extending into the gingiva and anastomosing with capillaries in the sulcus area.
  • Arterioles emerging from the crest of the interdental septa: extending parallel to the alveolar bone crest and anastomosing with vessels of the PDL.

Nerve Innervation of the Gingiva

• Most nerve fibers are myelinated and closely associated with blood vessels.
• Gingival innervation is derived from fibers arising from nerves in the PDL and from the labial, buccal, and palatal nerves.

Periodontal Ligament

• Principal fibers: collagenous, arranged in bundles, and follow a wavy course when seen on a longitudinal section.
• Six groups of principal fibers:
  • Transseptal fibers: extending interproximally over the crest of the alveolar bone, embedded in the adjacent teeth's cementum.
  • Alveolar crest fibers: extending in an oblique direction from the cementum to the alveolar crest, preventing tooth extrusion and providing resistance to lateral movement.
  • Horizontal fibers: extending from the cementum to the alveolar bone at right angles, perpendicular to the long axis of the tooth.
  • Oblique fibers: extending in a coronal direction from the cementum to the alveolar bone, forming the largest group of periodontal ligament fibers.
  • Apical fibers: extending from the cementum to the alveolar bone at the apical region of the tooth socket, radiating in an irregular manner.
  • Interradicular fibers: extending from the cementum to the alveolar bone in the furcation areas of multi-rooted teeth.

Junctional Epithelium

• A collar-like band of stratified squamous non-keratinizing epithelium, surrounding the tooth and located immediately apical to the sulcular epithelium.
• Length: ranges from 0.25 to 1.35 mm.
• Width: 10-29 cells wide at the coronal end, tapering apically to 1-2 cells wide.
• Apical termination: located at the cementoenamel junction in healthy tissue.
• Consists of two basal laminae: external basal lamina attaching the junctional epithelium to the gingival connective tissue, and internal basal lamina attaching the junctional epithelium to the tooth.

Attached Gingiva

• Width: Total gingival width (gingival margin to the mucogingival line) - sulcus or pocket depth.
• Width differs in different areas of the mouth, generally greatest in the incisors region (3.5-4.5 mm in the maxilla, 3.3-3.9 mm in the mandible), and narrower in the posterior segments (1.9 mm in the maxillary and 1.8 mm in the mandibular first premolars).

Functional Types of Oral Mucosa

• Masticatory mucosa: covers the gingiva and hard palate, with a keratinized or parakeratinized stratified squamous epithelium, and a lamina propria with two layers (papillary and reticular).
• Lining mucosa: covers all soft tissue of the oral cavity except the gingiva, hard palate, and dorsal surface of the tongue, with a non-keratinized epithelium (except on the vermillion border of the lip, where it is keratinized).
• Specialized mucosa: restricted to the dorsal surface of the tongue, with a keratinized epithelium, and characterized by the presence of surface papillae and taste buds.

Periodontal Ligament Functions

• Physical: attachment of the tooth to the bone via principal fibers, and absorption of occlusal forces.
• Formative: formation of connective tissue components by activities of connective tissue cells.
• Remodeling: by activities of connective tissue cells that are able to form as well as resorb cementum, PDL, and alveolar bone.
• Nutritive: through blood vessels that maintain the vitality of its various cells.
• Sensory: proprioceptive and tactile sensitivity is imparted through the PDL, sensed by the trigeminal nerve.

Gingival Epithelium

• Consists of stratified squamous epithelium with three distinct areas: the outer oral epithelium, the sulcular epithelium, and the junctional epithelium.
• Sulcular epithelium: a semipermeable membrane allowing seepage of tissue fluid from the gingiva into the gingival sulcus and entry of injurious bacterial products into the gingiva.

Mechanisms of Plaque Mineralization

• Two main categories:
  • Mineral precipitation: results from a local rise in the degree of saturation of calcium and phosphate ions.
  • Seeding agents: induce small foci of calcification that enlarge and coalesce to form a calcified mass.### Colonization and Plaque Maturation
• Microorganisms attach to tooth surfaces, forming microcolonies or biofilms, which lead to the development of periodontal disease
• Interbacterial connections occur through specific stereochemical interactions of protein and carbohydrate molecules on bacterial cell surfaces
• At least 18 genera of oral bacteria have shown coaggregation, including Fusobacterium nucleatum, which possesses surface molecules that foster cell-to-cell interactions

Plaque Formation and Maturation

• Plaque formation begins immediately after tooth surface cleaning, with rate affected by diet, age, salivary flow, oral hygiene, tooth alignment, systemic disease, and host factors
• Composition of plaque changes over time, with:
  • Days 1-2: Young plaque consists of cocci (e.g. Streptococcus mutans and sanguis)
  • Days 2-4: Coccistill dominate, with increasing numbers of filamentous forms and slender rods
  • Days 4-7: Filaments increase, with a more mixed flora appearing
  • Days 7-14: Vibrios and spirochetes appear, with increased gram-negative and anaerobic organisms
  • Days 14-21: Vibrios and spirochetes prevail, with gingivitis evident clinically

Plaque as a Biofilm

• Dental plaque biofilm has a similar structure to all biofilms, with microcolonies encased in a polysaccharide matrix
• Heterogenous structure with open fluid-filled channels, allowing for nutrient passage and communication between bacteria
• Intercellular matrix composed of organic and inorganic materials from saliva, gingival crevicular fluid, and bacterial products
• Biofilm allows for quorum sensing, regulating gene expression through signaling compounds

Periodontal Disease and Bone Loss

• Bacterial plaque is the primary etiologic factor for periodontal disease
• Bone loss occurs through:
  • Horizontal bone loss: uniform reduction in bone height, with margins remaining perpendicular to the tooth surface
  • Vertical or angular defect: bone loss occurs in an oblique direction, with the base of the defect resting apical to the surrounding bone
  • Osseous crater: concavity in the interdental bone, more common in posterior segments

Periodontal Pockets

• Periodontal pocket: pathological extension of the gingival sulcus, leading to destruction of supporting periodontal tissues
• Suprabony pocket: base of the pocket is coronal to the alveolar bone
• Intrabony pocket: base of the pocket is apical to the alveolar bone level
• Signs and symptoms: bleeding, suppuration, tooth mobility, diastema formation, pain, and foul taste

Furcation Involvement

• Invasion of the bifurcation and trifurcation of multi-rooted teeth by periodontal disease
• Classified as grades I-IV, with grade I being incipient bone loss and grade IV being total bone loss with through-and-through opening
• Treatment involves eliminating the involvement, with guided tissue regeneration and bone grafting having better results

Drug-Induced Gingival Enlargement

• Side effect of certain anticonvulsants, immunosuppressants, and calcium channel blockers
• Characteristics: painless, mulberry-shaped, pale pink, and resilient, with a lobulated surface
• Histopathology shows pronounced connective tissue and epithelial hyperplasia

Periodontal Probing

• Used to assess periodontal health, locate, measure, and determine the configuration of periodontal pockets
• Typical probe: thin, rodlike, tapered instrument with a blunt, rounded tip
• Inserts into the pocket with firm, gentle pressure, and walked around each surface of the tooth
• Provides the most accurate assessment of periodontal pocket depth and loss of attachment### Periodontal Probing
• The correct probe force is approximately 10-20 grams, which depresses the thumb pad by 1-2 mm.
• When probing, a hard ledge may block the passage of the probe, which is usually calculus; gently lift the probe away from the tooth and attempt to proceed apically again.
• The probe should be inserted parallel to the vertical axis of the tooth and "walked" circumferentially around each surface of each tooth to detect areas of deepest penetration.

Measuring Recession and Attached Gingiva

• Recession is the measurement of the migration of the free gingival margin apical to the CEJ of the tooth, measured as a positive value.
• The recession measurement added to the probe depth at a particular site indicates the amount of periodontal attachment that has been lost at that site.
• To measure the amount of attached gingiva:
  • Place the probe on the external surface of the gingiva and measure from the mucogingival junction to the gingival margin to determine the width of the total gingiva.
  • Insert the probe and measure the probing depth.
  • Subtract the probing depth from the total gingival measurement to get the width of the attached gingiva.

Probing Techniques

• Tilting the probe can affect the accuracy of the measurements; the probe should be flat against the tooth near the gingival margin with the probe approximately parallel to the long axis of the tooth for insertion.
• In the presence of inflammation, the probe may extend apical to the most coronal extent of the junctional epithelium and give a slightly greater depth than is actually present.

Periodontal Inflammation and Bacteremia

• Patients at risk for bacterial endocarditis need to be given antibiotic prophylaxis prior to performing periodontal probing.
• The presence of inflammation leads to a longer duration of bacteremia with resultant risks for patients at risk of acute bacterial endocarditis.

Toothbrush Trauma and Gingival Recession

• Toothbrush trauma can cause gingival recession and abrasion of enamel and/or cementum.
• Hard-bristle toothbrushes should be avoided, and soft-bristle toothbrushes with a dentifrice of optimum abrasiveness should be used.
• Dentin is abraded 25 times faster and cementum 35 times faster than enamel, leading to root surface abrasion and root sensitivity.

Gingival Clefts and Root Sensitivity

• Gingival clefts (aka Stillman's clefts) are narrow grooves that extend from the crest of the gingiva to the attached gingiva.
• Root hypersensitivity is a common problem, often occurring spontaneously when the root becomes exposed due to gingival recession or pocket formation.
• The primary symptom of root hypersensitivity is cold sensitivity.

Desensitizing Agents and Treatment

• Desensitizing agents act through the precipitation of crystalline salts on the dentin surface, which block dentinal tubules.
• Various in-office products and procedures for desensitization of dentin include cavity varnishes, anti-inflammatory agents, and treatments that partially obturate dentinal tubules.

Gingival Recession and Periodontal Therapy

• Gingival recession can occur secondary to periodontal therapy, increasing the risk for cervical abrasion and dentinal sensitivity.
• The patient will often complain of cold sensitivity, and the hypersensitivity will sometimes subside in time with daily plaque removal using a soft brush.

Oral Hygiene and Dental Professional Evaluation

• The dental professional should evaluate brushing technique and monitor hard and soft tissue conditions at each recall visit.
• Faulty placement, overaggressive movement or pressure, or the use of a hard toothbrush can lead to hard and soft tissue damage.
• The most common cause of gingival recession is tooth injury (abrasion).