Biology

Dental and Oral Biology

967 Questions

Dental and Oral Biology focuses on the structure, development, and function of teeth and oral tissues. It covers key concepts like dental formulas, tooth eruption, and common oral diseases. These topics are essential for medical and biology entrance examinations.

Dental formulaTooth anatomyMilk teethOral diseasesTooth decay

Dental and Oral Biology Questions

Multiple choice

Which of the following is false about cornocobs structure?

  1. Cornocob structure are highly specific cell-to-cell interactions.

  2. Cornocob appearance is seen in supragingival plaque towards tooth surface.

  3. The cornocob formations have Gram-negative rod-shaped bacterial cells.

  4. Central Gram-positive core supporting outer coccal cells is called cornocob arrangement.

  5. Central Gram-negative core supporting outer coccal cells is called cornocob arrangement.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Central Gram-negative core supporting outer coccal cells is called cornocob arrangement.

Multiple choice

Gingiva in children is

  1. more keratinized and more stippled

  2. more keratinized and less stippled

  3. less keratinized and more stippled

  4. less keratinized and less stippled

  5. none of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Attached gingiva appears less dense than in adults.

Multiple choice

All are contraindications for pulpotomy, except:

  1. mobility

  2. absence of coronal pus

  3. pain on percussion

  4. periodontitis involving pulp
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mobility is due to loss of alveolar bone support. Pulpotomy is a process designed to remove the infected pulp in the coronal pulp so that vitality of the pulp is maintained in the radicular part. This is not indicated when mobility is already present.

Multiple choice

The following is true about lathe cut amalgam:

  1. Has low creep

  2. Requires least amount of mercury

  3. Has tensile strength, comparable to high copper unicompositional alloys

  4. Achieves lowest compressive strength at 1 hour
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Amalgam alloys can be classified under various headings. One of them is based on the shape of the alloys particles. They can be either Lathe cut or Spherical or Spheroidal.

Multiple choice

Gutta percha is dissolved in all, except:

  1. chloroform

  2. halothane

  3. xylol

  4. xylene
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Other solvents are: methylchloroform, carbon - disulfide, carbon - tetrachloride, benzene, eucalyptol oil, rectified white turpentine.

Multiple choice

The pin used in pin restoration of a root canal treated tooth is:

  1. self-threaded pin

  2. cemented pin

  3. frictional pin

  4. All of the above.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pins are used in restoration to improve the retention form. Cemented pins are retained passively in a pin hole which is from 0.001 to 0.002 inches bigger in diameter than the pin. Hence, there is no stress during the pin placement and that is why this is indicated in RC treated teeth.

Multiple choice

Which of the following is not responsible for endogenous staining of teeth during development?

  1. Tetracycline

  2. Rh incompatibility

  3. Neonatal liver disease

  4. Vitamin C deficiency
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Discoloration of the teeth can be either extrinsic or intrinsic. Extrinsic stains are due to dietary sources or by habits. Intrinsic stains can be due to various causes:

  1. Enamel hypoplasia,
  2. Fluorosis,
  3. Tetracycline staining,
  4. Pulpal hemorrhage
Multiple choice

Permeability of dentin does not depend upon:

  1. smear layer

  2. diffusion coefficient of fluid

  3. convection of fluid

  4. length of dentinal tubules
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Permeability of the dentin depends on the diameter and the length of the tubules. Convection coefficient relates to the amount heat transferred through the fluids. This convection has no bearing on the permeability.

Multiple choice

A nonactive carious lesion in dentin may be easily identified by all of the following, except

  1. Pain on excavation

  2. Soft and cheesy in consistency

  3. Dark and hard

  4. Presence of dark pigmentation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Active carious lesions means bacteria are actively demineralizing enamel/dentin. The surface would be soft and cheesy, dark in colour and there will be pain on excavation. In a nonactive lesion, the bacteria and the host will be in the state of equilibrium. The tooth surface will be dark but hard.

Multiple choice

In a class - II cavity preparation, the axiopulpal line angle is rounded to:

  1. prevent the fracture of enamel

  2. prevent the fracture of amalgam

  3. prevent the fracture of gingival seat

  4. prevent the fracture of dentin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In an amalgam restoration, all the internal line angles are rounded because the stress concentration needs to be reduced. This is one of the principles of resistance form.

Multiple choice

A nonactive carious lesion is characterized by all of the following, except

  1. Pain on excavation

  2. Soft and cheesy in consistency

  3. Dark brown or black colour

  4. Dental plaque covers the lesion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a non active lesion, the bacteria and the host will be in the state of equilibrium. The tooth surface will be dark but hard. There is no demineralization at this stage.

Multiple choice

Sterilization of Gutta percha points is done by:

  1. hot salt sterilizer

  2. autoclaving

  3. chemical solutions

  4. dry heat
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

GP becomes soft at temperature above 64oC. Option a, b and d use heat for sterilization. GP can not be heat sterilized, hence it is submerged in 5% solution of NaOCI for one minute.  Then, it should be rinsed with ethyl alcohol to remove crystalline NaOCI before obturation. Otherwise, this will interfere with the seal of obturation.

Multiple choice

Incipient or recurrent caries can be detected before they are visible on a radiograph by:

  1. visible light

  2. ultrasonic light

  3. fibre optic trans-illumination

  4. digital fibre optic trans-illumination
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Even though ultrasonic detection also can help in diagnosis of incipient lesion, digital FOTI is the only dental diagnostic imaging instrument to be approved by the FDA for detection of incipient, frank and recurrent caries.

Multiple choice

A porcelain laminate veneer during adhesion gets bonding interface from:

  1. composite resin matrix, luting agent, etched enamel, silane - coupling agent

  2. composite resin matrix, etched enamel, silane - coupling agent

  3. composite resin matrix, luting agent, etched enamel

  4. etched enamel, luting agent, silane - coupling agent
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Porcelain laminates are permanent aesthetic restoration, which mark the progress in acid etch, bonding and aesthetic restorative techniques. The bond of etched porcelain laminates to enamel is considerably stronger than any other laminate system.