Prognosis practice questions for the periodontics Qualifying Exam
Prognosis connects diagnosis to the plan. Expect questions that weigh tooth factors against patient factors, and that ask which tooth to keep, which to treat and which to replace.
2027 ABP blueprint domain: Prognosis
5%of our mock exams
~10of 200 full-length mock questions
49questions on this domain in the bank
What the blueprint covers
The 2027 Qualifying Exam blueprint lists these objectives for this domain:
Short- and long-term prognosis for individual teeth and the dentition, periodontal and mucogingival
Short- and long-term implant prognosis, before and after placement, from site and patient factors
Using prognosis to build a comprehensive treatment plan
High-yield areas
Furcation involvement, mobility and crown-to-root ratio in molar survival
Smoking, diabetes, grade C disease and maintenance compliance
Root coverage predictability by recession type and interdental attachment
Implant risk with a history of periodontitis, radiation, antiresorptives and bruxism
Strategic value: when a guarded tooth is worth treating
How to study it
Learn the factors that move prognosis most, then practice deciding between keeping, treating and replacing a tooth in a full-mouth context, not one tooth at a time.
Free practice questions: Prognosis
4 questions from the bank, with the full rationale and source. Pick your answer, then open the rationale.
Question 1 of 4 · hardPrognosis
A 29-year-old nonsmoker has RT1 recessions on teeth #5, #6 and #7, each 2 to 3 mm deep. At #5 there is 3 mm of keratinized tissue apical to the recession and the gingiva is 1.2 mm thick. At #6 there is 3 mm of keratinized tissue and the gingiva is 0.6 mm thick. At #7 there is 2.5 mm of keratinized tissue and the gingiva is 1.0 mm thick. The plan is a multiple-tooth coronally advanced flap with a site-specific connective tissue graft. Which site most needs the graft?
Tooth #5
Tooth #6
Tooth #7
All three teeth equally
No site, since enamel matrix derivative can replace the graft
Show answer and rationale
Answer: B. Tooth #6
A (incorrect): Tooth #5 has more than 2 mm of keratinized tissue and gingiva thicker than 0.84 mm. It meets the criteria for the flap without a graft.
B (correct): A coronally advanced flap without a graft is indicated when more than 2 mm of keratinized tissue lies apical to the recession and the soft tissue is more than 0.84 mm thick. Only #6 falls below the thickness threshold, so a site-specific approach grafts #6 alone, which limits the graft size and donor site morbidity while protecting the weakest site.
C (incorrect): Tooth #7 has more than 2 mm of keratinized tissue and 1.0 mm of gingiva, which is above the 0.84 mm threshold. It does not need a graft under a site-specific approach.
D (incorrect): Grafting every site is a valid option but not what a site-specific approach aims for. It increases the amount of palatal tissue needed and patient morbidity without a clear indication at #5 and #7.
E (incorrect): Enamel matrix derivative improves the results of the flap alone, but it does not add tissue thickness. A thin site at 0.6 mm is an indication for a connective tissue graft.
A 58-year-old woman completed treatment for stage III, grade B periodontitis 2 years ago and has been stable in supportive care. She asks whether her periodontal history affects the outlook for an implant replacing tooth #19. Which statement is most accurate?
Her risk equals that of a periodontally healthy patient once treated
Her history raises peri-implantitis risk but not the risk of implant loss
Her history makes implant treatment contraindicated
Her risk is raised only if #19 was lost to periodontitis
Her history raises the risk of implant loss and peri-implantitis
Show answer and rationale
Answer: E. Her history raises the risk of implant loss and peri-implantitis
A (incorrect): Treated periodontitis patients still carry a higher risk of implant complications than people who never had periodontitis. Treatment and maintenance reduce but do not remove that risk.
B (incorrect): The evidence for a higher risk of implant loss was rated strong, even stronger than the evidence for peri-implantitis. Both risks are increased.
C (incorrect): A history of periodontitis is a risk factor, not a contraindication. Implants in treated, well-maintained patients achieve high survival rates.
D (incorrect): The risk relates to the patient's susceptibility, not to the reason the particular tooth was lost. Her susceptibility applies to every implant site.
E (correct): A meta-analysis found a significantly higher risk of implant loss, more implant bone loss and a higher risk of peri-implantitis in patients with periodontitis than in periodontally healthy patients. Implants remain a reasonable option for her, but the higher risk should be part of informed consent and supportive care planning.
Source: Sgolastra F, Petrucci A, Severino M, Gatto R, Monaco A. Periodontitis, implant loss and peri-implantitis. A meta-analysis. Clin Oral Implants Res. 2015;26(4):e8-e16. Abstract. https://pubmed.ncbi.nlm.nih.gov/24382358/
Question 3 of 4 · hardPrognosis
A 55-year-old woman has an implant at #19 with less than 1 mm of keratinized mucosa on the buccal and a shallow vestibule. She reports discomfort when brushing the area. Compared with implants that have an adequate band of keratinized mucosa, which pattern of findings is most consistent with systematic review evidence for implants like this one?
More bleeding on probing and more radiographic bone loss
Deeper probing depths but no difference in plaque
More plaque, inflammation, recession and attachment loss
No significant difference in any peri-implant parameter
More radiographic bone loss but no difference in recession
Show answer and rationale
Answer: C. More plaque, inflammation, recession and attachment loss
A (incorrect): Neither bleeding on probing nor radiographic bone loss differed significantly between implants with and without adequate keratinized mucosa in the pooled analysis. These outcomes did not distinguish the two groups.
B (incorrect): Probing depth did not differ significantly, whereas plaque accumulation was significantly higher with inadequate keratinized mucosa. This option reverses the findings.
C (correct): The meta-analysis found significantly more plaque, higher gingival index scores, more mucosal recession and more attachment loss around implants without adequate keratinized mucosa. Bleeding on probing, probing depth and radiographic bone loss did not differ significantly, so a soft tissue graft would mainly aim at comfort, plaque control and margin stability.
D (incorrect): Several parameters, including plaque, inflammation, recession and attachment loss, were significantly worse without adequate keratinized mucosa. The review therefore does not support ignoring a deficient band.
E (incorrect): Mucosal recession was significantly greater with inadequate keratinized mucosa, while radiographic bone loss did not differ significantly. This option reverses the findings.
Source: Lin GH, Chan HL, Wang HL. The significance of keratinized mucosa on implant health: a systematic review. J Periodontol. 2013;84(12):1755-1767. Abstract, Results and Conclusion. https://pubmed.ncbi.nlm.nih.gov/23451989/
Question 4 of 4 · easyPrognosis
A 60-year-old man completed active therapy for stage III, grade B periodontitis. He travels for work and plans to come for supportive periodontal care 'when convenient,' perhaps every 18 months. He asks whether regular visits really change how many teeth he will lose. Which response is best supported by evidence?
Attendance matters only if he smokes or has diabetes
Tooth loss depends on home care alone once therapy is complete
Irregular attendance increases bleeding scores but not tooth loss
Regular attendance benefits only teeth that had periodontal surgery
Regular attendance is linked to significantly less tooth loss
Show answer and rationale
Answer: E. Regular attendance is linked to significantly less tooth loss
A (incorrect): The benefit of regular supportive care was shown across treated periodontitis patients, not only in those with systemic or behavioral risk factors. Every treated patient remains at risk of recurrence.
B (incorrect): Home care is essential, but professional supportive care adds monitoring, removal of subgingival biofilm and early retreatment of recurrent sites. Erratic attenders lose more teeth even when instructed in home care.
C (incorrect): Tooth loss, the hardest outcome, was significantly greater in erratic attenders. The effect is not confined to inflammation indices.
D (incorrect): The benefit applies to the dentition as a whole, whether or not teeth were treated surgically. Nonsurgically treated sites also need regular monitoring and instrumentation.
E (correct): A meta-analysis of studies with at least 5 years of follow-up found that patients who complied regularly with supportive periodontal therapy had a significantly lower risk and rate of tooth loss than erratic attenders. Compliance is one of the most important patient factors in overall prognosis.
Source: Lee CT, Huang HY, Sun TC, Karimbux N. Impact of patient compliance on tooth loss during supportive periodontal therapy: a systematic review and meta-analysis. J Dent Res. 2015;94(6):777-786. Abstract. https://pubmed.ncbi.nlm.nih.gov/25818586/
For exam preparation only, not clinical advice.
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