ABP Regenerative Techniques 3 — Questions and Answers
Question 1: Xenografts used in periodontal bone regeneration are derived from which source?
- Synthetic calcium phosphate ceramics
- Human cadaver bone
- Bovine or porcine bone (Correct answer)
- Coral-derived hydroxyapatite only
Correct answer: Bovine or porcine bone
Xenografts are derived from non-human animal sources, most commonly bovine (cow) or porcine (pig) bone, which is processed to remove organic components and reduce antigenicity.
Question 2: A patient undergoes GTR for a 7mm three-wall intrabony defect. Six months post-op, re-entry shows 4mm of bone fill. What percentage of the defect was regenerated?
- 43%
- 57% (Correct answer)
- 67%
- 75%
Correct answer: 57%
4mm of bone fill in a 7mm defect equals 4/7 = 57% defect resolution, which is a standard way to express regenerative outcomes at re-entry.
Question 3: Which antibiotic is most commonly recommended as a systemic adjunct during regenerative periodontal surgery due to its anti-collagenase properties?
- Amoxicillin
- Metronidazole
- Doxycycline (Correct answer)
- Clindamycin
Correct answer: Doxycycline
Doxycycline is recommended as a systemic adjunct because it inhibits host-derived matrix metalloproteinases (MMPs) in addition to its antimicrobial properties, protecting the regenerating matrix.
Question 4: The Lindhe classification of furcation defects designates Class III as:
- Horizontal probe penetration less than one-third of tooth width
- Horizontal probe penetration more than one-third but not through-and-through
- Through-and-through furcation involvement (Correct answer)
- Furcation with vertical bone loss
Correct answer: Through-and-through furcation involvement
Lindhe Class III furcation involvement means the furcation probe passes completely through the furcation from buccal to lingual (or mesial to distal), indicating a through-and-through defect.
Question 5: Which statement BEST describes the mechanism of action of recombinant human bone morphogenetic protein-2 (rhBMP-2) in periodontal regeneration?
- It acts as a scaffold providing physical support for cell attachment
- It induces mesenchymal stem cell differentiation toward an osteoblastic lineage (Correct answer)
- It primarily stimulates angiogenesis to improve blood supply
- It inhibits osteoclast activity to prevent bone resorption
Correct answer: It induces mesenchymal stem cell differentiation toward an osteoblastic lineage
rhBMP-2 is an osteoinductive growth factor that binds to cell surface receptors and induces uncommitted mesenchymal stem cells to differentiate into osteoblasts via the SMAD signaling pathway.
Question 6: During root surface conditioning prior to placement of EMD, the recommended concentration and type of acid used is:
- 37% phosphoric acid for 15 seconds
- 24% EDTA gel for 2 minutes (Correct answer)
- 50% citric acid for 3 minutes
- 17% EDTA for 1 minute
Correct answer: 24% EDTA gel for 2 minutes
The manufacturer (Straumann/Biora) recommends PrefGel, which contains 24% EDTA, applied for 2 minutes to remove the smear layer and condition dentin before EMD application.
Question 7: Which of the following is the PRIMARY advantage of using a resorbable membrane over a non-resorbable membrane for GTR?
- Better space maintenance capacity
- Superior long-term clinical outcomes
- Elimination of a second surgical procedure for membrane removal (Correct answer)
- Lower cost of materials
Correct answer: Elimination of a second surgical procedure for membrane removal
The primary advantage of resorbable membranes is that they eliminate the need for a second surgical procedure to remove the membrane, reducing patient morbidity and simplifying treatment.
ABP Regenerative Techniques 3
Xenografts used in periodontal bone regeneration are derived from which source?