Free NDAEB Dental Sciences Foundations Questions and Answers 1 — Questions and Answers
Question 1: Which of the following muscles of mastication is primarily responsible for protruding and depressing the mandible (opening the jaw)?
- Masseter
- Temporalis
- Lateral pterygoid (Correct answer)
- Medial pterygoid
Correct answer: Lateral pterygoid
The lateral pterygoid muscle is unique among the muscles of mastication as its primary actions are to protrude (protract) the mandible and depress it, which is the main action when opening the mouth. The masseter, temporalis, and medial pterygoid muscles are all powerful elevators of the mandible, responsible for closing the jaw.
Question 2: A patient presents with creamy white, curd-like patches on their tongue and buccal mucosa that can be wiped off, leaving a reddened, tender surface. This clinical presentation is most characteristic of which oral condition?
- Leukoplakia
- Oral Candidiasis (Thrush) (Correct answer)
- Lichen Planus
- Aphthous Ulcer
Correct answer: Oral Candidiasis (Thrush)
Oral candidiasis, also known as thrush, is a fungal infection caused by an overgrowth of Candida yeast. It classically presents as white, wipeable patches in the mouth, which, when removed, reveal an erythematous (red) base. Leukoplakia is a white patch that cannot be wiped off, lichen planus often presents with a lace-like pattern, and aphthous ulcers are distinct, painful sores.
Question 3: In the development of the primary dentition, which tissue layer gives rise to the tooth enamel?
- Ectoderm (Correct answer)
- Mesoderm
- Endoderm
- Dental Papilla
Correct answer: Ectoderm
Tooth enamel, the hardest substance in the human body, is derived from the ectoderm, one of the three primary germ layers in the embryo. Specifically, it is formed by cells called ameloblasts, which originate from the enamel organ, an ectodermal structure. The mesoderm gives rise to connective tissues like dentin, pulp, and cementum, while the endoderm forms the lining of the digestive tract.
Question 4: A 7-year-old child presents for a routine check-up. You observe that they have lost their primary mandibular central incisors, and the permanent mandibular central incisors are erupting. They also have four permanent first molars. This stage of dental development is referred to as:
- Primary Dentition
- Succedaneous Dentition
- Mixed Dentition (Correct answer)
- Permanent Dentition
Correct answer: Mixed Dentition
The mixed dentition stage is characterized by the presence of both primary and permanent teeth in the mouth simultaneously. This period typically begins around age 6 with the eruption of the first permanent molar and/or the exfoliation of the primary mandibular central incisors, and it ends when all primary teeth have been lost.
Question 5: The mandible is the only freely movable bone of the skull. Which of the following landmarks is the specific part of the mandible that articulates with the temporal bone to form the temporomandibular joint (TMJ)?
- Coronoid process
- Mandibular condyle (Correct answer)
- Ramus
- Mental foramen
Correct answer: Mandibular condyle
The temporomandibular joint is formed by the articulation of the mandibular condyle (or condylar process) of the mandible with the mandibular fossa of the temporal bone. The coronoid process is an attachment site for the temporalis muscle. The ramus is the vertical part of the mandible, and the mental foramen is an opening for nerves and blood vessels.
Question 6: According to the principles of 'Routine Practices' in Canadian dental settings, when must hand hygiene be performed?
- Only after removing gloves
- Only before putting on gloves
- Before patient contact and after removing gloves (Correct answer)
- Only when hands are visibly soiled
Correct answer: Before patient contact and after removing gloves
Routine Practices, the Canadian equivalent of Standard Precautions, mandate that hand hygiene is a critical step to prevent cross-contamination. It must be performed at key moments, including before initial patient contact, before putting on gloves, and immediately after removing gloves. Relying on visible soilage is insufficient, as hands can be contaminated with microorganisms without being visibly dirty.
Free NDAEB Dental Sciences Foundations Questions and Answers 1
Which of the following muscles of mastication is primarily responsible for protruding and depressing the mandible (opening the jaw)?