Dental Calculus Classification

Dental Calculus

• The main cause of gum inflammation is bacterial plaque, other factors include calculus, bad bite, faulty dental work, orthodontic issues, self-harm, tobacco use and radiation therapy.
• Calculus is mineralized bacterial plaque forming on natural teeth and dental prosthetics.
• Calculus is classified as supragingival or subgingival based on its position relative to the gumline.

Classification of Dental Calculus

• Location:

  • Supragingival calculus is above the gumline.
  • Subgingival calculus is below the gumline.

• Source of Mineralization:

  • Salivary calculus
  • Serumal calculus (Jenkins, Stewart 1966)

• Surface:

  • Exogenous
  • Endogenous (Melz 1950)

• Initiation and rate of accumulation:

  • Calculus formers are categorized based on these factors.

Supra and Sub-gingival Calculus

• Supragingival calculus: Usually appears white or yellowish, hard, and clay-like. Often found on the buccal surfaces of upper molars and the lingual surfaces of lower incisors, affected by materials like tobacco and food coloring. Can be widespread throughout the mouth.
• Subgingival calculus: Located below the gumline, not easily seen during routine checkups. Evaluated by tactile perception with tools like dental explorers.

Calculus Composition

• Inorganic: Composed of approximately 70-90% inorganic materials, with calcium phosphate being the main component (76%), carbonates, and trace amounts of other metals.
• Organic: Mixture of protein-polysaccharide complexes, dead cells (epithelial), WBCs, and various microorganisms.

Calculus Attachment

• Calculus adheres to teeth via organic tissue, mechanical interactions with irregularities, and a close adaptation to existing tooth structures (like resorption lacunae or gently sloping areas)
• Calculus penetration is similar to penetration processes on bone areas.
• Calculus attachment to implants involves less intimate contact and can be easily removed from titanium implants.

Calculus Formation

• Calculus is formed from plaque mineralisation.
• Mineralization starts within 4-8 hours of plaque development, reaching 50% mineralisation in 2 days, and 60-90% in 12 days.
• Full development of mature crystalline composition can sometimes take months or years.

Role of Microorganisms in Calculus Formation

• Microbes are not always essential for calculus formation.
• Calculus develops in germ-free rodents, while saliva is the source for supra-gingival and gingival crevicular fluid for sub-gingival calculus formation.
• Some microbes have the ability to form intracellular apatite crystals.

Etiological Significance

• Non-mineralized plaque on calculus surface is a primary irritant initiating gingivitis.
• Mineralized portion of calculus contributes to continued plaque accumulation and can lead to periodontal pockets.
• Removal of calculus and plaque is a key step in periodontal treatment.