Hygiene Atlas

Atlas · Plate X · Periodontology · 01

The periodontium

The periodontium is four tissues: gingiva, periodontal ligament, cementum and alveolar bone. A healthy sulcus probes about 0.5-3 mm, and crevicular fluid increases with inflammation. The lamina dura lines each socket. Root concavities, such as the mesial of the maxillary first premolar, trap deposits and make instrumentation harder.

High-yield facts · 6

  1. The periodontium = gingiva, PDL, cementum and alveolar bone.S40
  2. Healthy sulcus depth is about 0.5-3 mm (histologic depth is about 0.69 mm).S40T2
  3. Gingival crevicular fluid increases with inflammation and carries neutrophils, antibodies and enzymes.S40
  4. Alveolar bone proper (lamina dura) lines the socket; supporting bone includes cortical plates and cancellous (trabecular) bone.S40
  5. Fenestration is a window of missing bone over the root with intact marginal bone; dehiscence is missing bone that reaches the margin.T3
  6. The maxillary first premolar mesial concavity and the mandibular first molar mesial root concavity are classic instrumentation traps.T3

Facts are written in our own words; each tag links to its source. Values marked "sources vary" differ between references, so check the one your program uses.