Foundational knowledge practice questions for the periodontics Qualifying Exam
The 2027 blueprint opens with the science under everything else: surgical anatomy, host response, pharmacology, imaging, grafting and implant materials, and reading the literature. It is the broadest domain on the exam.
2027 ABP blueprint domain: Foundational Knowledge
16%of our mock exams
~32of 200 full-length mock questions
160questions on this domain in the bank
What the blueprint covers
The 2027 Qualifying Exam blueprint lists these objectives for this domain:
Anatomy and physiology, including gross surgical anatomy and microanatomy of the periodontium
Biochemistry, immunology, genetics and epigenetics, and the pathophysiology of inflammation
Microbiology of the biofilm and host-mediated tissue destruction
Pharmacology: antimicrobials, analgesics and opioids, local anesthetics, sedation and reversal agents, emergency drugs, interactions and MRONJ
Radiologic and imaging sciences, and wound healing after non-surgical and surgical therapy
Material science: autografts, allografts, xenografts, alloplasts, biologics, membranes, sutures, hemostatics, implant and restorative materials
Statistics, the hierarchy of evidence and periodontal epidemiology
High-yield areas
Surgical anatomy that changes a plan: the greater palatine bundle, the mental foramen and anterior loop, lingual concavities and the posterior superior alveolar artery
RANKL and OPG, matrix metalloproteinases and the resolution of inflammation
Maximum local anesthetic doses, antibiotic spectra and interactions, and antiresorptive drugs
FDBA versus DFDBA, and what each biologic (EMD, rhPDGF-BB, rhBMP-2) is cleared for
Sensitivity, specificity, predictive values, NNT and reading a forest plot
How to study it
Learn basic science through the clinical decision it changes. For each drug, material or structure, know the one situation where it matters most in a periodontal practice, then practice calculation questions until relative and absolute risk feel automatic.
Free practice questions: Foundational knowledge
4 questions from the bank, with the full rationale and source. Pick your answer, then open the rationale.
Question 1 of 4 · moderateFoundational Knowledge
An endocrinologist asks whether treating periodontitis will improve glycemic control in her patients with type 2 diabetes. She has read a 514-patient multicenter randomized trial that stopped early for futility, finding no HbA1c difference at 6 months (-0.05%; 95% CI, -0.23 to 0.12%) despite improved probing depths. A 2022 Cochrane review of 30 randomized trials (2,443 participants) found a 0.43% absolute HbA1c reduction at 3 to 4 months, rated moderate certainty. Which summary is most accurate?
The largest single trial overrides the review, so therapy has no glycemic effect
The body of trials supports a modest HbA1c reduction with moderate certainty
The evidence is high certainty, so therapy can replace diabetes medication changes
The evidence is observational, so no conclusion about therapy is possible
Better probing depths in the null trial mean HbA1c will improve in practice
Show answer and rationale
Answer: B. The body of trials supports a modest HbA1c reduction with moderate certainty
A (incorrect): One trial, however large, is part of the body of evidence, not a replacement for it. A systematic review weighs all eligible trials, and the 2022 update doubled the number of included studies; a sensitivity analysis limited to trials at low risk of bias still supported a reduction in HbA1c.
B (correct): Moderate-certainty evidence from 30 trials shows that subgingival instrumentation reduces HbA1c by about 0.43 percentage points at 3 to 4 months compared with no treatment or usual care, with reductions of 0.30% at 6 months (12 trials) and 0.50% at 12 months (1 trial). The reviewers judged this reduction clinically significant and further trials unlikely to change the conclusion, while individual trials vary in population and result.
C (incorrect): The review rated the evidence as moderate, not high, certainty. Periodontal therapy is an addition to, not a substitute for, medical management of diabetes.
D (incorrect): Both sources are randomized trials, not observational studies. Randomized evidence on this question is abundant.
E (incorrect): Probing depth is a periodontal outcome, and its improvement did not translate into an HbA1c change in that trial. Improvement in one measure does not guarantee change in a different outcome.
Source: Simpson TC, Clarkson JE, Worthington HV, et al. Treatment of periodontitis for glycaemic control in people with diabetes mellitus. Cochrane Database Syst Rev. 2022;4(4):CD004714. Abstract, Main results and Authors' conclusions. https://pmc.ncbi.nlm.nih.gov/articles/PMC9009294/ (trial: Engebretson SP, et al. JAMA. 2013;310(23):2523-2532, https://pmc.ncbi.nlm.nih.gov/articles/PMC4089989/)
Question 2 of 4 · hardFoundational Knowledge
A patient will have a hopeless maxillary premolar extracted and the socket grafted with freeze-dried bone allograft, with an implant planned about 4 to 5 months later. The surgeon is choosing between mineralized (FDBA) and demineralized (DFDBA) particulate processed from the same donor. Based on a randomized histologic comparison of the 2 materials, which outcome should she expect if she chooses DFDBA?
Greater preservation of ridge width with a similar share of vital bone
A lower share of vital bone but better preservation of ridge height
More residual graft particles with a similar share of vital bone
No meaningful difference in vital bone, residual graft or dimensions
More vital bone and less residual graft with similar ridge dimensions
Show answer and rationale
Answer: E. More vital bone and less residual graft with similar ridge dimensions
A (incorrect): Ridge width and height changes did not differ significantly between the groups. The difference between the materials was histologic, not dimensional.
B (incorrect): DFDBA produced more vital bone, not less, and ridge height preservation was similar. This option reverses the histologic finding.
C (incorrect): Mineralized FDBA, not DFDBA, left more residual graft particles in the cores. DFDBA also produced a greater share of vital bone.
D (incorrect): The dimensional outcomes were similar, but the histology differed significantly. Treating the materials as equivalent ignores the vital bone and residual graft differences.
E (correct): With single-donor material, DFDBA sites had about 38% vital bone versus about 25% for FDBA at roughly 19 weeks, with much less residual graft (about 9% versus 25%). Ridge width and height changes were not significantly different, so DFDBA favors bone vitality while FDBA does not preserve dimensions better.
Source: Wood RA, Mealey BL. Histologic comparison of healing after tooth extraction with ridge preservation using mineralized versus demineralized freeze-dried bone allograft. J Periodontol. 2012;83(3):329-336. Abstract, Results and Conclusion. https://pubmed.ncbi.nlm.nih.gov/21749166/
Question 3 of 4 · hardFoundational Knowledge
In a randomized trial in which 40% of control patients needed periodontal surgery, an adjunct produced a relative risk reduction of 25% that appeared constant across levels of baseline risk. A 45-year-old nonsmoker with localized stage III, grade A periodontitis has an estimated 8% baseline risk of needing surgery after instrumentation alone. Assuming the same relative risk reduction applies to him, what is his number needed to treat?
4
10
50
12.5
7
Show answer and rationale
Answer: C. 50
A (incorrect): 4 is the inverse of the relative risk reduction (1/0.25). That would be the number needed to treat only if the baseline risk were 100%.
B (incorrect): 10 is the number needed to treat in the trial population, whose control risk was 40% (0.40 x 0.25 = 0.10). It cannot be transferred to a patient whose baseline risk is much lower.
C (correct): The absolute risk reduction is the baseline risk multiplied by the relative risk reduction: 0.08 x 0.25 = 0.02. The number needed to treat is 1/0.02 = 50. With a constant relative effect, the number needed to treat rises sharply as baseline risk falls, which is why an adjunct can be worthwhile in high-risk patients and hard to justify in low-risk ones.
D (incorrect): 12.5 is the inverse of his baseline risk (1/0.08). This ignores the size of the treatment effect.
E (incorrect): About 7 would apply to a high-risk patient with a 60% baseline risk (0.60 x 0.25 = 0.15; 1/0.15). It overstates the benefit for this patient.
Source: Cook RJ, Sackett DL. The number needed to treat: a clinically useful measure of treatment effect. BMJ. 1995;310(6977):452-454. Abstract (extrapolation to a patient's baseline risk). https://pmc.ncbi.nlm.nih.gov/articles/PMC2548824/
Question 4 of 4 · easyFoundational Knowledge
A national health ministry using Global Burden of Disease estimates wants its periodontal screening program to identify severe periodontitis around the age at which new cases peak. Based on the global systematic review and meta-regression of severe periodontitis, which age group should the program emphasize?
Adolescents between 15 and 19 years
Adults in their early 20s
Adults older than 70 years
Adults in their mid to late 30s
Adults in their mid to late 50s
Show answer and rationale
Answer: D. Adults in their mid to late 30s
A (incorrect): Severe periodontitis is uncommon in adolescents, and this age group sits before the steep rise in prevalence. Adolescents with molar-incisor pattern periodontitis exist but are a small fraction of the global burden.
B (incorrect): Prevalence is still relatively low in the early 20s. The steep rise spans the third and fourth decades and is driven by new cases that peak near age 38.
C (incorrect): Prevalence remains high in older adults because it accumulates, but incidence peaks much earlier. Screening aimed at the oldest group finds established disease, often after tooth loss.
D (correct): In the Global Burden of Disease 2010 analysis, prevalence of severe periodontitis climbed sharply across the third and fourth decades because incidence peaked at about 38 years of age. Age-standardized prevalence was 11.2% in both 1990 and 2010, making it the sixth most prevalent condition worldwide. The Global Burden of Disease 2021 study estimated that severe periodontitis affected over 1 billion people (about 1,067 million), with an age-standardized prevalence of 12.50%.
E (incorrect): Incidence has already peaked by the late 50s. Screening in midlife remains useful but would start after the period of greatest new disease.
Source: Kassebaum NJ, Bernabe E, Dahiya M, Bhandari B, Murray CJ, Marcenes W. Global burden of severe periodontitis in 1990-2010: a systematic review and meta-regression. J Dent Res. 2014;93(11):1045-1053. Abstract. https://pmc.ncbi.nlm.nih.gov/articles/PMC4293771/ (2021 update: Nascimento GG, Alves-Costa S, Romandini M. Burden of severe periodontitis and edentulism in 2021, with projections up to 2050: the Global Burden of Disease 2021 study. J Periodontal Res. 2024;59(5):823-867. Abstract, Results. https://doi.org/10.1111/jre.13337)
For exam preparation only, not clinical advice.
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