Etiology practice questions for the periodontics Qualifying Exam
Etiology questions ask why a site broke down: the biofilm, a local factor, a systemic modifier, or a prosthesis that cannot be cleaned. Most are short cases where one finding explains the rest.
2027 ABP blueprint domain: Etiology of Periodontal and Peri-implant Diseases
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What the blueprint covers
The 2027 Qualifying Exam blueprint lists these objectives for this domain:
Etiological and contributing factors for periodontal diseases
Etiological and contributing factors for peri-implant diseases
Etiological and contributing factors for developmental and acquired conditions
High-yield areas
Dysbiosis and keystone pathogens versus older specific-plaque thinking
Local factors: cervical enamel projections, palatogingival grooves, overhangs and root proximity
Smoking and diabetes as risk factors, with dose and control
Peri-implantitis risk: history of periodontitis, no maintenance, excess cement and prosthesis design
Recession etiology, drug-influenced gingival enlargement and altered passive eruption
How to study it
For each condition, list the necessary cause, the local contributors and the systemic modifiers, in that order. Then read cases backward: from the finding to the most likely cause.
Free practice questions: Etiology
4 questions from the bank, with the full rationale and source. Pick your answer, then open the rationale.
Question 1 of 4 · moderateEtiology of Periodontal and Peri-implant Diseases
A 68-year-old man has a 4-implant fixed prosthesis in the maxilla with a ridge-lap design that prevents passage of interdental brushes or floss threaders. He brushes the occlusal and buccal surfaces daily. Two of the implants now have deep probing depths, suppuration and bone loss. Which factor most likely explains the disease at these implants?
Occlusal overload from the full-arch prosthesis
Titanium particle release from the abutments
A prosthesis that blocks hygiene access
Smoking-related peri-implant mucositis
Implant fracture with bacterial leakage
Show answer and rationale
Answer: C. A prosthesis that blocks hygiene access
A (incorrect): There is no evidence that occlusal overload is a risk indicator for peri-implantitis onset or progression. The blocked hygiene access is the more likely cause.
B (incorrect): The role of titanium particles cannot currently be evaluated. The prosthesis design that prevents cleaning offers a better-supported explanation.
C (correct): In patients referred for peri-implantitis, implants without access for proper oral hygiene were much more likely to have peri-implantitis than implants with access. Prosthesis design that limits cleaning is a key local factor, and current guidelines call for designs with good access and favorable contours.
D (incorrect): He is not described as a smoker, and the findings include bone loss, which indicates peri-implantitis rather than mucositis. Mucositis by definition has no bone loss beyond initial remodeling.
E (incorrect): Nothing in the history or radiographs suggests fracture. The pattern of disease at implants that cannot be cleaned fits plaque accumulation.
Source: Serino G, Strom C. Peri-implantitis in partially edentulous patients: association with inadequate plaque control. Clin Oral Implants Res. 2009;20(2):169-174. Abstract, Results and Conclusion. https://pubmed.ncbi.nlm.nih.gov/19077152/
Question 2 of 4 · hardEtiology of Periodontal and Peri-implant Diseases
A 56-year-old woman with stage III periodontitis had full-mouth scaling and root planing 10 days ago. A 7 mm pocket on the distal of a mandibular molar, which had heavy tenacious calculus, now has acute swelling, pain and suppuration, while other sites have improved. Which mechanism most likely explains the abscess?
Systemic antibiotic use that selected for opportunistic bacteria
Occlusal trauma from changes in tooth position after scaling
Hypersensitivity to the local anesthetic used during scaling
Coronal tightening over residual calculus that blocks drainage
Necrotizing periodontitis triggered by stress of treatment
Show answer and rationale
Answer: D. Coronal tightening over residual calculus that blocks drainage
A (incorrect): She had mechanical debridement and no antibiotics are described. The antibiotic-related mechanism applies when antimicrobials are taken without debridement.
B (incorrect): Occlusal trauma is not among the recognized causes of abscesses after periodontal treatment. The timing and residual deposits point to a drainage problem.
C (incorrect): Anesthetic hypersensitivity would not produce a localized suppurating pocket 10 days later at one site. The localized timing and residual calculus fit a drainage problem instead.
D (correct): After scaling and root planing, an abscess can form when inadequate scaling leaves calculus deep in the pocket while the coronal part of the pocket tightens and occludes drainage. Dislodged calculus fragments pushed into the tissue can produce the same result.
E (incorrect): Necrotizing disease presents with papillary necrosis, pain and bleeding across multiple sites. A single suppurating pocket after scaling is a periodontal abscess.
Source: Herrera D, Retamal-Valdes B, Alonso B, Feres M. Acute periodontal lesions (periodontal abscesses and necrotizing periodontal diseases) and endo-periodontal lesions. J Periodontol. 2018;89(Suppl 1):S85-S102. Periodontal abscess: Etiology, pathogenesis (after scaling and root planing). https://doi.org/10.1002/JPER.16-0642
Question 3 of 4 · hardEtiology of Periodontal and Peri-implant Diseases
A periodontist reviews 2 patients who each have cement remnants around single cement-retained implant crowns. Patient 1 has a history of treated stage III periodontitis; Patient 2 has never had periodontitis. Based on retrospective data comparing such patients, which outcome is most likely?
Both patients have the same risk, because cement alone determines the outcome
Patient 2 is more likely to develop peri-implantitis because healthy tissue reacts more strongly
Both patients will most likely develop reversible peri-implant mucositis
Patient 1 is more likely to develop peri-implantitis than Patient 2
Neither patient will develop disease unless they also smoke
Show answer and rationale
Answer: D. Patient 1 is more likely to develop peri-implantitis than Patient 2
A (incorrect): Outcomes differed by periodontal history. In periodontally healthy patients, many cement remnant sites showed only mucositis or no disease.
B (incorrect): There is no evidence that a periodontally healthy host reacts more strongly to cement. The data point the other way.
C (incorrect): In patients with a history of periodontitis, every implant with cement remnants progressed to peri-implantitis rather than stopping at mucositis. Mucositis was the more common outcome only in periodontally healthy patients.
D (correct): In a retrospective analysis, all implants with cement remnants in patients with a history of periodontitis developed peri-implantitis, while most remnant sites in periodontally healthy patients showed mucositis or no complication. Cement remnants combined with periodontal history appear to raise the risk.
E (incorrect): Smoking is not required for cement-related peri-implant disease. Disease was present at 85% of implants with cement remnants, and the outcome difference turned on periodontal history.
Source: Linkevicius T, Puisys A, Vindasiute E, Linkeviciene L, Apse P. Does residual cement around implant-supported restorations cause peri-implant disease? A retrospective case analysis. Clin Oral Implants Res. 2013;24(11):1179-1184. Abstract, Results and Conclusions. https://pubmed.ncbi.nlm.nih.gov/22882700/
Question 4 of 4 · moderateEtiology of Periodontal and Peri-implant Diseases
A 14-year-old boy whose parents emigrated from Morocco has 5 mm of interproximal attachment loss on all 4 first molars and on the mandibular incisors, with little plaque. His 12-year-old brother is periodontally healthy. Which microbial finding would most strongly support an infectious etiology for his disease?
High counts of Streptococcus mutans in supragingival plaque
Carriage of non-JP2 clones of A. actinomycetemcomitans
Carriage of the JP2 clone of A. actinomycetemcomitans
Candida albicans in the gingival sulcus
Actinomyces naeslundii as the dominant subgingival species
Show answer and rationale
Answer: C. Carriage of the JP2 clone of A. actinomycetemcomitans
A (incorrect): S. mutans is a cariogenic organism and is not an etiologic agent of molar-incisor pattern periodontitis.
B (incorrect): Non-JP2 clones carried a much smaller increase in risk than the JP2 clone. Their presence alone is weaker evidence for the cause of rapid attachment loss.
C (correct): In a prospective cohort of Moroccan adolescents, carriers of the JP2 clone had a markedly increased risk of new attachment loss, far higher than carriers of non-JP2 clones. This highly leukotoxic clone is concentrated in people of North and West African origin and fits a molar-incisor pattern in a young patient.
D (incorrect): Candida is associated with mucosal infection and, in HIV, with necrotizing lesions. It is not linked to molar-incisor pattern periodontitis in healthy adolescents.
E (incorrect): Actinomyces species are early colonizers associated with gingival health and gingivitis rather than rapid attachment loss in adolescents. Finding them would add nothing to the case for a specific infectious cause.
Source: Haubek D, Ennibi OK, Poulsen K, et al. Risk of aggressive periodontitis in adolescent carriers of the JP2 clone of Aggregatibacter (Actinobacillus) actinomycetemcomitans in Morocco: a prospective longitudinal cohort study. Lancet. 2008;371(9608):237-242. Abstract, Findings and Interpretation. https://pubmed.ncbi.nlm.nih.gov/18207019/
For exam preparation only, not clinical advice.
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