Periodontology
Periodontology
Periodontology is the study of the supporting structures of the teeth and the diseases that affect them. A candidate must master the anatomy of the periodontium (gingiva, periodontal ligament, cementum, alveolar bone), microbiology of dental plaque (supragingival vs. subgingival, gram-positive vs. gram-negative anaerobes), pathogenesis (host response, inflammatory mediators), and classification of periodontal diseases (2017 AAP/EFP classification). Also understand risk factors (smoking, diabetes, genetics), diagnostic tools (probing depth, clinical attachment level, bleeding on probing, radiographs), and treatment phases (initial therapy, surgical therapy, maintenance).
Trap: confusing probing depth with clinical attachment level. Probing depth is measured from the gingival margin; attachment level is from the cementoenamel junction. In questions, recession shifts the margin, so a deep pocket with recession may have a large attachment loss but a shallow probing depth. Another trap: assuming that bleeding on probing alone indicates active disease; it is a risk indicator, not a diagnosis. Also, the 2017 classification uses staging (severity and complexity) and grading (progression risk), not the old terms like "aggressive periodontitis."
Worked example: A patient has probing depths of 5 mm on the mesial of tooth 14, with the gingival margin 2 mm apical to the CEJ. The clinical attachment level is 5 + 2 = 7 mm. This indicates stage III periodontitis (interdental CAL ≥5 mm). The rule of thumb: CAL = probing depth + recession (if margin is apical to CEJ). Remember that staging uses the worst site, not the average.
Key concepts: biofilm-induced vs. non-biofilm-induced diseases, gingivitis vs. periodontitis (reversible vs. irreversible attachment loss), host modulation, and maintenance (supportive periodontal therapy).