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Periodontics · single question

What is the biological width composed of?

  1. Sulcus depth + junctional epithelium
  2. Alveolar bone + periosteum
  3. Junctional epithelium (JE) + connective tissue attachment (CT)
  4. Gingival sulcus + alveolar bone
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Correct answer: C. Junctional epithelium (JE) + connective tissue attachment (CT)

  • A. The SULCUS depth (up to 3mm) is NOT part of biological width — the sulcus is the space ABOVE the tissue attachment. Biological width is JE + CT below the base of the sulcus.
  • B. Alveolar bone and periosteum are not components of biological width — they lie below the connective tissue attachment.
  • C. Biological width = JUNCTIONAL EPITHELIUM (~0.97mm) + CONNECTIVE TISSUE attachment (~1.07mm) = approximately 2mm total. It is the physiologic space needed between the base of the gingival sulcus and the alveolar bone crest. Crown margins placed within the biological width cause chronic inflammation, bone loss, and periodontal disease. The modern term is 'supracrestal tissue attachment.'
  • D. Neither the gingival sulcus nor the alveolar bone are components of biological width.

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