MJDF Part 1 - Membership of Joint Dental Faculties Periodontology Fundamentals 1 — Questions and Answers
Question 1: Regarding the junctional epithelium, which of the following statements is CORRECT?
- It is a keratinized stratified squamous epithelium that resists microbial ingress
- It attaches to the tooth surface via hemidesmosomes and an internal basal lamina, and has a very high cell turnover rate (Correct answer)
- It extends from the gingival margin apically to the alveolar crest
- It has a lower permeability than the oral sulcular epithelium
Correct answer: It attaches to the tooth surface via hemidesmosomes and an internal basal lamina, and has a very high cell turnover rate
The junctional epithelium is non-keratinized and attaches to enamel or cementum through hemidesmosomes and an internal basal lamina. Its cell turnover is remarkably rapid (approximately 3–6 days), far faster than oral epithelium, and it is highly permeable — allowing both crevicular fluid egress and immune cell trafficking into the sulcus.
Question 2: According to the Hamp et al. (1975) classification, a Class II furcation involvement is defined as:
- Horizontal probe penetration into the furcation of less than 3 mm
- Horizontal probe penetration of 3 mm or more into the furcation, but not extending through-and-through (Correct answer)
- Complete through-and-through horizontal probing of the furcation with a Nabers probe
- Vertical bone loss confined within the furcation vault without horizontal component
Correct answer: Horizontal probe penetration of 3 mm or more into the furcation, but not extending through-and-through
Hamp et al. graded furcation involvement by horizontal probe depth: Class I is less than 3 mm, Class II is 3 mm or more but does not exit the opposite side, and Class III is a complete through-and-through defect. A calibrated Nabers probe is used to assess each class clinically.
Question 3: Which statement BEST describes the relationship between poorly controlled type 2 diabetes mellitus and periodontitis?
- Diabetes increases periodontal susceptibility, but there is no evidence that treating periodontitis influences glycaemic control
- Periodontitis directly causes type 2 diabetes through systemic low-grade inflammation
- A bidirectional relationship exists: hyperglycaemia worsens periodontal outcomes, and severe periodontitis can adversely affect glycaemic control (Correct answer)
- The association is limited to type 1 diabetes and is not clinically relevant in type 2 diabetes
Correct answer: A bidirectional relationship exists: hyperglycaemia worsens periodontal outcomes, and severe periodontitis can adversely affect glycaemic control
Evidence supports a bidirectional link. Chronic hyperglycaemia impairs neutrophil function and promotes advanced glycation end-product (AGE) accumulation, amplifying periodontal inflammation. Conversely, intensive periodontal treatment of severe periodontitis has been shown to reduce HbA1c by approximately 0.4%, indicating that periodontal disease can adversely affect systemic glycaemic control.
Question 4: In the Cairo 2011 gingival recession classification, a Recession Type 2 (RT2) defect is characterised by:
- Buccal recession with no clinically detectable interproximal clinical attachment loss
- Buccal recession where the interproximal CAL loss is greater than the buccal CAL loss
- Buccal recession accompanied by interproximal CAL loss that is less than or equal to the buccal CAL loss, with the interproximal CEJ still detectable (Correct answer)
- Complete loss of the interdental papilla with through-and-through exposure of the interproximal root surface
Correct answer: Buccal recession accompanied by interproximal CAL loss that is less than or equal to the buccal CAL loss, with the interproximal CEJ still detectable
The Cairo classification replaces Miller's system. RT1 has no interproximal attachment loss. RT2 has interproximal CAL loss that is present but does not exceed the buccal CAL loss, and the interproximal CEJ is still identifiable clinically. RT3 has interproximal CAL loss greater than the buccal loss, making root coverage prognosis less predictable.
Question 5: On a periapical radiograph, a vertical (angular) alveolar bone defect in periodontitis is BEST characterised by:
- A uniform, horizontal reduction of bone height across adjacent teeth with the bone crest remaining roughly perpendicular to the long axis of the teeth
- An oblique, asymmetric pattern of bone loss creating an infrabony defect in which the base of the defect is apical to the adjacent alveolar crest (Correct answer)
- Widening of the periodontal ligament space without any loss of alveolar crest height
- Bone loss visible exclusively in the furcation region of multi-rooted posterior teeth
Correct answer: An oblique, asymmetric pattern of bone loss creating an infrabony defect in which the base of the defect is apical to the adjacent alveolar crest
Vertical or angular defects result in an oblique bone margin where the base of the pocket lies apical to the surrounding crestal bone, forming an infrabony pocket. This contrasts with horizontal bone loss, in which crestal bone height is reduced evenly and the residual crest remains approximately perpendicular to the tooth surface. Infrabony defects are often associated with more advanced or aggressive local disease.
Question 6: Porphyromonas gingivalis is described as a 'keystone pathogen' in chronic periodontitis. Which of the following BEST explains this designation?
- It is the most numerically abundant organism in the subgingival biofilm of periodontitis patients
- Despite being present in low abundance, it disproportionately disrupts host innate immunity — particularly complement and neutrophil pathways — driving polymicrobial dysbiosis (Correct answer)
- It produces a unique collagenase that directly destroys alveolar bone, making it more destructive than any other periodontal pathogen
- It is the only organism capable of forming the early colonisers that allow later pathogenic species to attach to the tooth surface
Correct answer: Despite being present in low abundance, it disproportionately disrupts host innate immunity — particularly complement and neutrophil pathways — driving polymicrobial dysbiosis
P. gingivalis is the archetypal keystone pathogen: even at low numbers it hijacks complement signalling (via gingipain-mediated C5a generation and C3 degradation) and impairs neutrophil oxidative killing. This immune evasion creates a permissive environment that allows the broader dysbiotic community — including the 'red complex' organisms — to flourish and cause tissue destruction disproportionate to P. gingivalis abundance alone.
MJDF Part 1 - Membership of Joint Dental Faculties Periodontology Fundamentals 1
Regarding the junctional epithelium, which of the following statements is CORRECT?