Cementum Clinical Correlation Quiz

Cementum Related Clinical Correlation

• Cementum is the calcified avascular mesenchymal tissue forming the outer layer of root surfaces.
• It begins at the cemento-enamel junction (CEJ) and continues to the apex.
• Cementum is part of the periodontium apparatus.
• It plays a key role in anchoring teeth to the bone via the periodontal ligament.

Table of Contents

• Introduction
• Structures of cementum
• Function
• Developmental anomalies
• Systemic conditions that influence cementum
• Clinical application

What is Cementum?

• Hardness is less than dentin.
• Color: light yellow, distinguishable from enamel (darker hue) and dentin (lighter).
• Thinnest at the cemento-enamel junction (20-50 µm), thickest towards the apex (150-200 µm).
• Cellular cementum permeability is greater than acellular cementum (more permeable from dentin and PDL side).
• With age, this permeability decreases.

Composition

• Primarily composed of organic and inorganic materials (50-55% organic, 45-50% inorganic).
• Inorganic component: calcium phosphate in the form of hydroxyapatite crystals.
• Organic component: collagen protein and polysaccharides (mainly collagen type I & III).
• Main collagen sources: Sharpey's fibers (extrinsic), and intrinsic fibers in the cementum matrix, both produced by fibroblasts.

Classification of Cementum

• Based on location: coronal or radicular.
• Based on cellularity: cellular or acellular.
• Based on fibers: extrinsic or intrinsic.

Acellular and Cellular Cementum

Presence or Absence of Fibers

• Fibrillar cementum: contains densely packed collagen fibrils.
• Afibrillar cementum: lacks dense collagen fibers.
• Categorized further as acellular afibrillar, acellular intrinsic fiber cementum, acellular extrinsic fibers, cellular mixed stratified cementum, and cellular intrinsic fiber cementum.

Structures in Cementum

• Cemento-enamel junction (CEJ): the junction between enamel and cementum.
  • Types: overlapping, edge-to-edge, and gap.
• Clinical significance of CEJ: reference point for healthy individuals, calculate clinical attachment loss, & determine progression of periodontal disease.
• Cemento-dentinal junction (CDJ): the terminal apical area where cementum joins internal root canal dentin.
  • Clinical significance: attachment medium for collagen fibers to alveolar bone, major source of repair for root surfaces.

Intermediate Cementum

• Thin layer of hard tissue between cementum and dentin.
• Contains cellular remnants of Hertwig's epithelial root sheath.
• Predominantly seen in the apical two-thirds of molars and premolars.
• Does not exhibit the characteristics of dentin or cementum.
• Function: seals the surface of sensitive root dentin, attachment of cementum to dentin.

Function of Cementum

• Anchorage: Provides a medium for collagen fiber attachment, binding the tooth to the alveolar bone.
• Adaptation: Continuous cementum deposition adapts to tooth movement, maintaining vertical dimensions.
• Repair: Secondary (cellular) cementum responsible for repair and maintaining root surface integrity.
  • Two types of repair: anatomic and functional.

Cementum Resorption

• Local Factors: Cysts, tumors, embedded teeth, trauma from occlusion, excessive orthodontic force, periapical or periodontal disease.
• Systemic Factors: Paget's disease, hypophosphatasia, calcium deficiency.

Cementum Resorption & Orthodontic Tooth Movement

• Cementum is more resistant to resorption than bone.
• Differences in vascularization & metabolism between cementum and bone affect resistance to pressure.
• Surface layers of cementum have higher fluoride content, leading to greater resistance to acidic dissolution.
• Bone resorption occurs on the pressure side and bone formation on the tension side during tooth movement.

Age Changes

• Cementum deposition is continuous throughout life, but slower in older age, particularly in the apical areas.
• Permeability decreases with age.
• Surface becomes irregular due to calcification.

Developmental Anomalies

• Hypercementosis: Thickening of cementum, potentially localized or generalized.
  • Causes: teeth without antagonists, pulpal or periodontal infections.
  • Clinical features: vital teeth insensitive to percussion, generalized thickening with nodular enlargement, large apical third roots, potential spikes.
  • Radiographic appearance: thickened and dulled roots, apex rounding.
  • Management: hypercementosis itself does not require treatment. Focus on the primary etiology, consider extraction / sectioning if needed.
• Cemental Tear: Detachment of cementum fragment.
  • Etiology: acute trauma from occlusion.
  • Clinical significance: a contributing factor to adult periodontitis.
• Cementicles: Globular mass of cellular cementum, less than 0.05mm.
  • Types: free, sessile/attached, interstitial/embedded.
• Ankylosis: Fusion of cementum and alveolar bone.
  • Etiology: chronic periapical infection, tooth reimplantation, and occlusal trauma.
  • Clinical presentation: lack of physiological mobility, metallic sound upon percussion, infraocclusion, and radiographic appearance of bone filling the PDL space. No specific treatment.
• Concrescence: Fusion of teeth by cementum fusion.
  • Etiology: traumatic injury, crowding of teeth during maturation.

Systemic Conditions Influencing Cementum

• Hypophosphatasia: Rare inherited metabolic disorder causing mutations in the ALPL gene, leading to deficient TNSALP activity, interfering with hydroxyapatite crystal formation.
  • Oral signs (premature tooth loss, dental hypoplasia, alveolar bone deficiency) often precede skeletal symptoms.
  • Treatment: enzyme replacement therapy, pain relief (NSAIDs), physical therapy, dental care (fluoride treatment, sealants), and prosthetics/implants, vitamin D & calcium supplements, and lifestyle modifications,
• Paget's Disease: Characterized by enhanced bone resorption.
  • Clinical features: predominantly affecting middle-aged adults, involvement of facial bones (maxilla and mandible), widening of alveolar ridge, and loosening of teeth.
  • Characteristic radiographic appearance: cotton-wool appearance of bone, generalized hypercementosis of teeth.
  • Histologic appearance: jigsaw or mosaic pattern.

Clinical Importance and Applications

• Cementum and Periodontal Health: Root planning and scaling to remove calculus and infected or roughened cementum. Guided tissue regeneration uses barriers/growth factors to stimulate new cementum and periodontal ligament.
• Cementum and Tooth Sensitivity: Gingival recession, exposing cementum, can lead to tooth sensitivity. Desensitizing agents (potassium nitrate, fluoride compounds) can address this.
• Restorative Procedures: Covering exposed cementum with composite resin can protect the root surface.
• Soft Tissue Grafting: May be needed for severe gingival recession to cover exposed cementum.