DHA Periodontics exam questions

6 worked Periodontics practice questions

Original exam-style questions from the bank, spread across the blueprint domains. They are not real or recalled exam questions. Try each one, then open the answer for the rationale and reference. None of them appear in the free mock exam, so reading them will not spoil it.

1. Question 1 · Classification and Diagnosis

   A 30-year-old non-smoker without diabetes has radiographic bone loss of 60% of root length at the worst tooth. What grade is assigned using the bone loss/age ratio?

   1. AGrade C
   2. BGrade A
   3. CGrade B
   4. DGrade cannot be assigned
   Show answer and explanation

   Correct answer: A. Grade C

   The ratio is 60/30 = 2.0. A ratio above 1.0 indicates Grade C (rapid progression); 0.25-1.0 is Grade B. Grade can be assigned from indirect evidence when no longitudinal data exist.

   Reference: Tonetti MS, Greenwell H, Kornman KS. J Periodontol 2018

2. Question 2 · Non-Surgical Therapy and Pharmacotherapy

   According to the EFP S3 guideline, what does the first step of periodontitis therapy include?

   1. ASubgingival instrumentation of every deep pocket
   2. BAccess flap surgery for all residual deep pockets
   3. CSystemic antibiotics for every patient
   4. DHygiene advice, supragingival cleaning, risk control
   Show answer and explanation

   Correct answer: D. Hygiene advice, supragingival cleaning, risk control

   Step 1 aims to change behaviour: oral hygiene instruction, professional supragingival biofilm removal and control of risk factors such as smoking and diabetes. Subgingival instrumentation is Step 2.

   Reference: Sanz M, et al. EFP S3 Level Clinical Practice Guideline, J Clin Periodontol 2020

3. Question 3 · Non-Surgical Therapy and Pharmacotherapy

   A patient uses chlorhexidine 0.2% mouthwash for 3 weeks after periodontal surgery. What is the most common side effect?

   1. AFibrous gingival enlargement
   2. BGeneralised dentine sensitivity
   3. COral candidal infection
   4. DBrown extrinsic tooth staining
   Show answer and explanation

   Correct answer: D. Brown extrinsic tooth staining

   Brown extrinsic staining of teeth, restorations and tongue is the most common side effect of chlorhexidine, along with altered taste. Gingival enlargement is linked to certain systemic drugs, not chlorhexidine.

   Reference: Newman and Carranza's Clinical Periodontology, 13th ed.

4. Question 4 · Peri-Implant Diseases and Implant Therapy

   No baseline data exist for an implant placed 5 years ago. Which finding meets the 2017 case definition of peri-implantitis?

   1. ABleeding, PD 6 mm and 3 mm bone loss
   2. BBleeding with PD 3 mm, no bone loss
   3. CBone loss of 0.5 mm in year one
   4. DMucosal redness without bleeding
   Show answer and explanation

   Correct answer: A. Bleeding, PD 6 mm and 3 mm bone loss

   Without baseline records, peri-implantitis is defined by bleeding or suppuration with PD of 6 mm or more and/or bone levels 3 mm or more apical to the implant platform. Bleeding without bone loss is peri-implant mucositis.

   Reference: Berglundh T, et al. J Clin Periodontol 2018 (2017 World Workshop)

5. Question 5 · Peri-Implant Diseases and Implant Therapy

   Two adjacent implants are planned in the anterior maxilla. What minimum inter-implant distance helps preserve the bone crest and papilla?

   1. A1 mm
   2. B3 mm
   3. C1.5 mm
   4. D6 mm
   Show answer and explanation

   Correct answer: B. 3 mm

   Tarnow showed that an inter-implant distance of 3 mm or more limits crestal bone loss between implants. The 1.5 mm figure is the minimum distance between an implant and a natural tooth.

   Reference: Tarnow DP, et al. J Periodontol 2000

6. Question 6 · Periodontal Anatomy, Microbiology and Host Response

   Why is Porphyromonas gingivalis described as a 'keystone pathogen'?

   1. AAt low abundance it drives dysbiosis by subverting immunity
   2. BIt is the most abundant species in all subgingival plaque
   3. CIt is the first organism to colonise freshly cleaned enamel
   4. DIt causes disease only when it invades blood vessels
   Show answer and explanation

   Correct answer: A. At low abundance it drives dysbiosis by subverting immunity

   The keystone hypothesis holds that P. gingivalis, even at low abundance, disrupts complement and immune signalling to convert a symbiotic biofilm into a dysbiotic, inflammatory one. It is not the most abundant species; early colonisers are mainly streptococci.

   Reference: Hajishengallis G, et al. Nat Rev Microbiol 2012