DDS Doctor of Dental Surgery MCQ 4 — Questions and Answers
Question 1: Which microorganism is considered the primary etiological agent in the initiation of dental caries?
- Streptococcus salivarius
- Lactobacillus acidophilus
- Streptococcus mutans (Correct answer)
- Actinomyces viscosus
Correct answer: Streptococcus mutans
Streptococcus mutans is the principal organism initiating dental caries due to its high acidogenic and aciduric properties and ability to produce glucan for biofilm adherence.
Question 2: Which radiographic view is best for evaluating the condylar head and the temporomandibular joint space?
- Panoramic radiograph
- Lateral cephalogram
- Transcranial radiograph (Correct answer)
- Waters' view
Correct answer: Transcranial radiograph
The transcranial (lateral oblique) projection provides a useful view of the lateral aspect of the condylar head and the joint space.
Question 3: During tooth preparation for a full cast crown, the occlusal reduction for a posterior tooth should generally be:
- 0.5 mm
- 1.0 mm
- 1.5–2.0 mm (Correct answer)
- 3.0–3.5 mm
Correct answer: 1.5–2.0 mm
Adequate occlusal reduction of 1.5–2.0 mm is required for posterior full cast crowns to provide sufficient metal thickness and strength.
Question 4: A patient with poorly controlled type 2 diabetes is more susceptible to periodontitis primarily because of:
- Increased salivary glucose feeding bacteria
- Impaired neutrophil function and advanced glycation end-products (Correct answer)
- Xerostomia reducing plaque buffering
- Increased calculus deposition
Correct answer: Impaired neutrophil function and advanced glycation end-products
Hyperglycemia impairs neutrophil chemotaxis and phagocytosis and promotes formation of AGEs, which upregulate inflammatory cytokines and damage periodontal tissues.
Question 5: Which suture material is preferred for intraoral wounds because it dissolves without removal?
- Silk
- Nylon
- Polyglycolic acid (Dexon) (Correct answer)
- Prolene
Correct answer: Polyglycolic acid (Dexon)
Resorbable sutures like polyglycolic acid (Dexon) or polyglactin (Vicryl) are preferred intraorally because patients do not need to return for removal.
Question 6: The landmark 'pterygomandibular raphe' serves as a guide for which injection technique?
- Posterior superior alveolar block
- Inferior alveolar nerve block (Correct answer)
- Greater palatine block
- Infraorbital block
Correct answer: Inferior alveolar nerve block
The pterygomandibular raphe is the buccal landmark lateral to which the needle is directed for the inferior alveolar nerve block.
Question 7: Which type of bone graft material contains living cells capable of differentiation into osteoblasts?
- Alloplast
- Xenograft
- Allograft
- Autograft (Correct answer)
Correct answer: Autograft
Autografts (patient's own bone) contain viable osteogenic cells, osteoinductive factors, and an osteoconductive scaffold, making them the gold standard for bone regeneration.
DDS Doctor of Dental Surgery MCQ 4
Which microorganism is considered the primary etiological agent in the initiation of dental caries?