Free NDEB Dental Sciences Questions and Answers — Questions and Answers
Question 1: A patient has a history of radiation therapy for thyroid cancer. Three weeks after an extraction, there is increasing pain and a non-healing extraction socket with exposed sequestrated bone. The most likely diagnosis is _________:
- osteoradionecrosis. (Correct answer)
- alveolar osteitis
- metastatic thyroid cancer
- epulis granulomatosa
Correct answer: osteoradionecrosis.
Explanation: <br> In a patient with a history of radiation therapy, increasing pain and a nonhealing extraction socket with exposed bone suggest osteoradionecrosis, a complication characterized by bone death due to radiation-induced vascular damage.
Question 2: Which of the following is the most common cause of fracture of nickel-titanium (NiTi) rotary endodontic instruments?
- NiTi files that are too small in diameter.
- Rotational speed that is too slow.
- NiTi files that have too little taper.
- Torsional stresses that are too high. (Correct answer)
Correct answer: Torsional stresses that are too high.
Explanation: <br> Torsional stresses occur when the tip of the NiTi rotary endodontic instrument binds within the root canal, leading to excessive stress and potential fracture of the instrument.
Question 3: When prescribing codeine, patients should be informed ________:
- to complete the prescribed course.
- that it may cause diarrhea.
- to avoid consuming alcohol. (Correct answer)
- that it may cause hypertension.
Correct answer: to avoid consuming alcohol.
Explanation: <br> Patients should be advised to avoid consuming alcohol while taking codeine because it can enhance the sedative effects of the medication and increase the risk of adverse reactions such as dizziness, drowsiness, and respiratory depression.
Question 4: Dental porcelain has ________:
- low hardness and low impact strength.
- low hardness and high impact strength.
- high hardness and low impact strength. (Correct answer)
- high hardness and high impact strength.
Correct answer: high hardness and low impact strength.
Explanation: <br> Dental porcelain exhibits high hardness, making it resistant to wear, but it has low impact strength, meaning it is prone to fracture or chipping under forceful impacts.
Question 5: An SNA of 88˚ most likely indicates a maxilla positioned ________:
- posteriorly.
- normally.
- anteriorly. (Correct answer)
Correct answer: anteriorly.
Explanation: <br> An SNA angle of 88˚ indicates that the maxilla is positioned anteriorly relative to the cranial base.
Question 6: Disinfection is a process that ______:
- decreases the viral load to safe levels.
- selectively reduces Gram-positive microorganisms.
- eradicates pathogenic viruses.
- reduces the number of microorganisms. (Correct answer)
Correct answer: reduces the number of microorganisms.
Explanation: <br> Disinfection is a process that aims to reduce the number of microorganisms, including bacteria, viruses, fungi, and protozoa, to a level where they are no longer harmful or pose a lower risk of infection or disease transmission.
Question 7: Arterial blood flows continuously through capillaries during both systole and diastole because ________:
- arterioles can regulate their diameters. (Correct answer)
- arteries possess compliant walls.
- veins possess valves on their inner surface.
- the beating heart spends more time in diastole than in systole.
- blood undergoes laminar flow through capillary beds
Correct answer: arterioles can regulate their diameters.
Explanation: <br> Arterial blood flows continuously through capillaries during both systole and diastole because arterioles, the small branches of arteries, can regulate their diameters to maintain blood flow and distribute blood appropriately to tissues.
Question 8: Plaque becomes more cariogenic when ________:
- Streptococcus sanguis predominates
- pyogenic organisms predominate
- it has become heavily calcified.
- acidogenic bacteria and fermentable carbohydrate are present. (Correct answer)
Correct answer: acidogenic bacteria and fermentable carbohydrate are present.
Explanation: <br> Plaque becomes more cariogenic when acidogenic bacteria (those that produce acid) are present along with fermentable carbohydrates, as this combination promotes acid production, leading to demineralization of tooth structure and dental caries formation.
Question 9: Surface enamel is more highly mineralized than the rest of the enamel because _______:
- crystallites are deposited parallel to the surface. (Correct answer)
- older ameloblasts produce more amelogenins.
- surface enamel is prismless.
- older ameloblasts digest protein more efficiently.
Correct answer: crystallites are deposited parallel to the surface.
Explanation: <br> Surface enamel is more highly mineralized than the rest of the enamel because the crystallites are deposited parallel to the surface, resulting in greater mineral density and hardness.
Question 10: A facial nerve injury at the stylomastoid foramen will result in _______:
- no loss of motor innervation to the orbicularis oculi.
- no loss of innervation to the posterior belly of the digastric muscle.
- loss of taste sensation from the anterior 2/3 of the tongue. (Correct answer)
- no loss of parasympathetic innervation to the lacrimal gland.
Correct answer: loss of taste sensation from the anterior 2/3 of the tongue.
Explanation: <br> The facial nerve, also known as the seventh cranial nerve, exits the skull through an opening called the stylomastoid foramen. This nerve innervates various muscles of the face, including those responsible for facial expressions and taste sensation on the anterior 2/3 of the tongue. Therefore, an injury to the facial nerve at the stylomastoid foramen would result in loss of taste sensation from the anterior 2/3 of the tongue.
Question 11: When taking the working length radiograph for tooth 1.4 with 2 canals, the superimposition of the roots can be avoided by
- changing the horizontal angulation of the X-ray beam. (Correct answer)
- changing the vertical angulation of the X-ray beam.
- using the paralleling technique
- using the bisecting technique
- using a digital image
Correct answer: changing the horizontal angulation of the X-ray beam.
Explanation: <br> To avoid superimposition of the roots when taking a working length radiograph for a tooth with two canals, such as tooth 1.4, the best approach is to change the horizontal angulation of the X-ray beam. Adjusting the horizontal angulation helps to separate the roots and provides a clearer view of each canal's position within the tooth.
Free NDEB Dental Sciences Questions and Answers
A patient has a history of radiation therapy for thyroid cancer.
Three weeks after an extraction, there is increasing pain and a non-healing extraction socket with exposed sequestrated bone.
The most likely diagnosis is _________: