NBDE Ultimate 3 — Questions and Answers
Question 1: The biologic width is composed of which two tissue components?
- Sulcular epithelium and junctional epithelium
- Junctional epithelium and supracrestal connective tissue attachment (Correct answer)
- Alveolar bone and connective tissue attachment
- Gingival sulcus and alveolar crest fibers
Correct answer: Junctional epithelium and supracrestal connective tissue attachment
The biologic width (~2 mm) consists of the junctional epithelium (~1 mm) and the supracrestal connective tissue attachment (~1 mm) coronal to the alveolar crest.
Question 2: In Andrews' Six Keys to normal occlusion, the mesiobuccal cusp of the maxillary first molar occludes with the:
- Mesial fossa of the mandibular first molar
- Embrasure between the mandibular second premolar and first molar
- Buccal groove of the mandibular first molar (Correct answer)
- Distal fossa of the mandibular second premolar
Correct answer: Buccal groove of the mandibular first molar
The mesiobuccal cusp of the maxillary first molar occludes in the buccal groove of the mandibular first molar in an ideal Class I molar relationship.
Question 3: Which periodontal fiber group runs roughly parallel to the root surface and perpendicular to the long axis of the tooth, connecting cementum to alveolar bone?
- Oblique fibers
- Alveolar crest fibers (Correct answer)
- Apical fibers
- Transseptal fibers
Correct answer: Alveolar crest fibers
Alveolar crest fibers run horizontally from the cementum just below the CEJ to the alveolar crest, resisting lateral forces.
Question 4: Alveolar osteitis (dry socket) following tooth extraction is most frequently associated with which site?
- Maxillary incisors
- Maxillary canines
- Mandibular third molars (Correct answer)
- Maxillary first molars
Correct answer: Mandibular third molars
Mandibular third molars have the highest incidence of dry socket, estimated at 20-35%, due to poor blood supply, difficult extraction, and fibrinolytic activity in this region.
Question 5: Angle Class II Division 2 malocclusion is characterized by:
- Prognathic mandible with Class II molar relationship
- Retroclined maxillary central incisors with a deep overbite (Correct answer)
- Anterior crossbite with mandibular prognathism
- End-to-end molar relationship with significant crowding
Correct answer: Retroclined maxillary central incisors with a deep overbite
Class II Division 2 features a Class II molar relationship with lingually inclined maxillary central incisors, resulting in a deep (excessive) overbite.
Question 6: Which periodontal pathogen is most strongly associated with chronic adult periodontitis and is considered a keystone pathogen?
- Streptococcus mutans
- Porphyromonas gingivalis (Correct answer)
- Treponema denticola
- Fusobacterium nucleatum
Correct answer: Porphyromonas gingivalis
Porphyromonas gingivalis is the primary keystone pathogen in chronic periodontitis, disrupting host immune responses and promoting dysbiotic plaque communities.
Question 7: A patient with a non-displaced mandibular condyle fracture and intact occlusion is best managed with:
- Open reduction with internal fixation
- Closed reduction with maxillomandibular fixation for 6 weeks
- Conservative management with soft diet and physiotherapy (Correct answer)
- Condylectomy
Correct answer: Conservative management with soft diet and physiotherapy
Non-displaced condyle fractures with intact occlusion in adults are managed conservatively with a soft diet, analgesics, and jaw exercises to maintain mobility.
NBDE Ultimate 3
The biologic width is composed of which two tissue components?