Periodontology
What this domain tests
The 2018 World Workshop classification, the distinction between probing depth and attachment loss, risk assessment, and the escalation from non-surgical to surgical therapy.
Core rules
- Gingivitis is reversible inflammation of the gingiva with no attachment loss. Periodontitis is defined by clinical attachment loss plus radiographic bone loss.
- Staging (I–IV) describes severity and complexity of management, based on interdental attachment loss, bone loss percentage, tooth loss due to periodontitis, and complexity factors. Grading (A–C) describes rate of progression, based on bone loss/age, with grade modifiers such as smoking and HbA1c.
- Risk factors: smoking (independent risk factor, reduces bleeding), poorly controlled diabetes (grade modifier), plaque biofilm as the initiating factor, and host susceptibility as the determinant of severity.
- Non-surgical periodontal therapy is the foundational treatment; adjunctive systemic antibiotics are reserved for specific situations and are never a substitute for debridement.
- Peri-implant mucositis is reversible inflammation around an implant; peri-implantitis adds progressive bone loss and is not reversible.
Worked example
A 48-year-old non-smoker has 6 mm probing depths on two molars and radiographic bone loss of 40% of the root length; the worst tooth has bone loss/age near 1.0. Reasoning: interdental attachment loss of about 5 mm with 40% bone loss and fewer than four teeth lost places it in Stage III; the bone loss/age ratio places it in Grade B or C depending on the final index. The grade modulator is absence of smoking and unknown diabetes status - so an HbA1c check is indicated.
Traps
- Using probing depth alone as the diagnostic criterion for periodontitis.
- Expecting bleeding to be a reliable marker in a heavy smoker.
- Describing peri-implant mucositis as irreversible.