ORE Part 2 Periodontics — Questions and Answers
Question 1: According to the 2017 World Workshop classification, what defines Stage III periodontitis?
- Gingivitis with bleeding on probing only
- Interdental CAL of 1–2mm at site of greatest loss
- Interdental CAL ≥5mm, radiographic bone loss extending to the middle third of the root, and potential for tooth loss (Correct answer)
- Complete loss of attachment with spontaneous tooth exfoliation
Correct answer: Interdental CAL ≥5mm, radiographic bone loss extending to the middle third of the root, and potential for tooth loss
Stage III periodontitis is defined by interdental clinical attachment loss (CAL) of 5mm or more, radiographic bone loss extending to the middle third of the root or beyond, and complexity factors including furcation involvement (Class II or III), moderate ridge defects, and potential for tooth loss. It represents severe periodontitis with increasing complexity of management.
Question 2: What is the primary aetiological factor in the initiation of periodontal disease?
- Occlusal trauma
- Dental plaque biofilm (Correct answer)
- Genetic predisposition
- Smoking
Correct answer: Dental plaque biofilm
Dental plaque biofilm is the primary aetiological factor in the initiation of periodontal disease. The classic studies by Löe et al. (1965) demonstrated that experimental gingivitis develops within 2–3 weeks of plaque accumulation and resolves upon plaque removal. While risk factors such as smoking and genetics modify the host response, plaque is essential for disease initiation.
Question 3: A patient presents with 6mm probing depths and bleeding on probing after completing non-surgical periodontal therapy. What is the next step in management?
- Repeat oral hygiene instruction only
- Reassess at 3 months and consider surgical access for root debridement (Correct answer)
- Extract all affected teeth
- Prescribe long-term systemic antibiotics
Correct answer: Reassess at 3 months and consider surgical access for root debridement
After completing non-surgical therapy (Steps 1 and 2 of the BSP/EFP S3 clinical guideline), a reassessment is performed at 8–12 weeks. Residual pockets of 6mm or more with bleeding on probing indicate sites that have not responded adequately and may benefit from surgical access for thorough debridement, or adjunctive regenerative/resective procedures.
Question 4: Which periodontal probe marking system is used for the WHO Community Periodontal Index (CPI)?
- Williams probe with 1mm markings
- UNC-15 probe with 1mm markings to 15mm
- WHO/CPITN probe with a 0.5mm ball tip and markings at 3.5, 5.5, 8.5, and 11.5mm (Correct answer)
- Nabers furcation probe
Correct answer: WHO/CPITN probe with a 0.5mm ball tip and markings at 3.5, 5.5, 8.5, and 11.5mm
The WHO/CPITN probe has a distinctive 0.5mm ball tip designed to follow the contour of the root surface without penetrating the junctional epithelium. Its colour-coded band between 3.5 and 5.5mm allows quick categorisation of periodontal status. It is the standard probe used in epidemiological surveys worldwide.
Question 5: What is the biological width (now termed supracrestal tissue attachment), and why is it clinically significant?
- The width of keratinised gingiva, important for aesthetics
- The combined height of junctional epithelium and connective tissue attachment above the alveolar crest, violation of which causes inflammation and bone loss (Correct answer)
- The depth of the gingival sulcus in health
- The width of the interdental papilla
Correct answer: The combined height of junctional epithelium and connective tissue attachment above the alveolar crest, violation of which causes inflammation and bone loss
The supracrestal tissue attachment (formerly biological width) comprises the junctional epithelium (~0.97mm) and the connective tissue attachment (~1.07mm) above the alveolar bone crest, totalling approximately 2mm. Placing restorative margins within this zone triggers chronic inflammation and crestal bone resorption as the body attempts to re-establish this biological dimension.
Question 6: Which bacterium is most strongly associated with aggressive (now Stage III/IV Grade C molar-incisor pattern) periodontitis?
- Streptococcus mutans
- Porphyromonas gingivalis
- Aggregatibacter actinomycetemcomitans (Correct answer)
- Fusobacterium nucleatum
Correct answer: Aggregatibacter actinomycetemcomitans
Aggregatibacter actinomycetemcomitans (Aa) is strongly associated with the molar-incisor pattern of periodontitis (formerly localised aggressive periodontitis). It produces leukotoxin that destroys neutrophils, impairing local host defence. The JP2 clone of Aa, producing enhanced levels of leukotoxin, is particularly virulent and associated with rapid attachment loss in young patients.
ORE Part 2 Periodontics
According to the 2017 World Workshop classification, what defines Stage III periodontitis?