Periodontology
This domain tests the distinction between reversible gingival inflammation and destructive periodontitis, the current classification and staging system, risk assessment, and the treatment sequence from behaviour change to surgery and maintenance.
Health, gingivitis and periodontitis
Plaque biofilm initiates gingivitis, which is reversible and confined to the gingiva with bleeding on probing and no attachment loss. Periodontitis is a chronic multifactorial inflammatory disease with clinical attachment loss and radiographic bone loss; pocket depth alone does not define it. Risk factors include smoking, poorly controlled diabetes, genetic susceptibility and plaque retentive factors.
The 2018 classification
The current system separates staging (severity and extent) from grading (progression risk).
- Stage I–II: mild to moderate attachment loss, bone loss in the coronal third, no tooth loss from periodontitis at Stage I.
- Stage III: severe disease, bone loss extending to the middle third, probing depths of 6 mm or more, up to four teeth lost.
- Stage IV: advanced disease with five or more teeth lost, masticatory dysfunction or bite collapse.
- Grade A/B/C: slow, moderate or rapid progression, judged by bone loss relative to age plus smoking and glycaemic control.
Treatment sequence
- Behaviour change: oral hygiene instruction, smoking cessation, glycaemic control.
- Subgingival instrumentation (scaling and root surface debridement) with re-evaluation at 8–12 weeks.
- Adjuncts: systemic amoxicillin plus metronidazole only in defined advanced cases alongside debridement, never alone.
- Surgery: access flaps, resective or regenerative procedures, guided tissue regeneration, bone grafting.
- Supportive periodontal care at individually risk-based intervals.
Worked example
A 45-year-old smoker has 40% radiographic bone loss on first molars, probing depths of 7 mm, three teeth lost to periodontitis and HbA1c of 8.2%. Reasoning: severity reaches Stage III–IV depending on tooth loss and function; bone loss high for age plus smoking and poor glycaemic control place the patient in Grade C. This drives a more intensive regimen, closer maintenance and explicit smoking and diabetes counselling.
Traps that cost marks
- Equating probing depth with attachment loss where there is recession.
- Relying on bleeding on probing: smoking and diabetes can mask it, so absence is not reassurance.
- Prescribing antibiotics as a substitute for mechanical debridement.
- Forgetting drug-induced gingival overgrowth (phenytoin, nifedipine, ciclosporin) and necrotising gingivitis in immunocompromised or stressed patients.