Free NDAEB Dental Sciences Foundations Questions and Answers 1

Question 1

Which of the following muscles of mastication is primarily responsible for protruding and depressing the mandible (opening the jaw)?

Accepted Answer

Lateral pterygoid

Answer

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?

Accepted Answer

Oral Candidiasis (Thrush)

Answer

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?

Accepted Answer

Ectoderm

Answer

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:

Accepted Answer

Mixed Dentition

Answer

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)?

Accepted Answer

Mandibular condyle

Answer

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.

(NDAEB) National Dental Assisting Examination Board Practice Test

(NDAEB) National Dental Assisting Examination Board Practice Test

Free NDAEB Dental Sciences Foundations Questions and Answers 1