In a demographic cycle, if death rate is declining but there is no increase in birth rate, this population is called as:

 # In a demographic cycle, if death rate is declining but there is no increase in birth rate, this population is called as:

A. Early expanding

B. Low stationary

C. High stationary

D. Declining

The correct answer is A. Early expanding.

There is a demographic cycle of 5 stages through which a nation passes.

First stage (High stationary): This stage is characterized by a high birth rate and high death rate which cancel each other and the population remains stationary. 

Second stage (Early expanding): The death rate begins to decline while the birth rate remains unchanged. As the birth rates remain high, the population starts to grow rapidly.

Third stage (Late expanding)- Death rate declines still further and birth rate tends to fall, but population tends to grow as birth rate supersedes the death rates, but rates of population growth decelerates.

Fourth stage (Low stationary)- This stage is characterized by low birth and low death rate with the result that the population becomes stationary. Most industrialized countries have gone through a demographic transition from a high birth and high death rates to low birth and low death rates.

Fifth stage (Declining): Population begins to decline because birth rate is lower than death rate.

What is common to all Staphylococci?

 # What is common to all Staphylococci?

A. All are gram positive

B. Common in nosocomial infections

C. All inhibited by penicillin G

D. All of the above

The correct answer is A. All are gram positive.

Staphylococcus is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. Staphylococcus species are facultative anaerobic organisms (capable of growth both aerobically and anaerobically).

Staphylococcus can cause a wide variety of diseases in humans and animals through either toxin production or penetration. Staphylococcal toxins are a common cause of food poisoning, for they can be produced by bacteria growing in improperly stored food items. The most common sialadenitis is caused by staphylococci, as bacterial infections.Staphylococci break down leucine into isovaleric acid, the main odor of foot odor.

The widespread incidence of antibiotic resistance across various strains of S. aureus, or across different species of Staphylococcus has been attributed to horizontal gene transfer of genes encoding antibiotic/metal resistance and virulence. A recent study demonstrated the extent of horizontal gene transfer among Staphylococcus to be much greater than previously expected, and encompasses genes with functions beyond antibiotic resistance and virulence, and beyond genes residing within the mobile genetic elements.

When the denture border is overextended on posterior region, common complaint by the patient is:

   # When the denture border is overextended on posterior region, common complaint by the patient is:

A. Improper retention

B. Difficulty in swallowing 

C. Difficulty in speech

D. Excess salivation

The correct answer is A. Improper retention. 

Persistent gagging can occur due to overextended denture borders especially in the posterior part of maxillary denture and the distolingual part of mandibular denture. Gagging usually produces displacement of the denture.

When the denture border is overextended on distolingual region, difficulty in swallowing occurs. The overextension in the distolingual sulcus should be corrected.

Ref: Nallaswamy

Stages of Tooth Development in a Multirooted Tooth

 Description of modified Moorrees' stages (Moorrees et al., 1963a,b) used to identify tooth developmental stages of multirooted teeth. 

Average vertical length a mandible moves in a chewing cycle is:

  # Average vertical length a mandible moves in a chewing cycle is:

A. 3-5 mm

B. 10-12 mm

C. 16-20 mm

D. 50-60 mm

The correct answer is C. 16-20 mm.

Chewing is highly complex oral motor behavior usually seen in the frontal plane in simple form. No archetypal chewing cycle exists. The means of the dimensions of the chewing cycle are between 16 and 20 mm for vertical movements and between 3 and 5 mm for lateral movements. The duration of the cycle varies from 0.6 to 1 second depending on the type of food. The speed of masticatory movement varies within each cycle, both according to the type of food and among individuals. Speed, duration, and form of the chewing cycle vary with the type of occlusion, kind of food, and presence of dysfunction.

Reference: Wheeler's 10th Edition Page 263

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Oblique ridge at the centre of occlusal surface is reduced to the level of:

  # Oblique ridge at the centre of occlusal surface is reduced to the level of:

A. Central groove

B. Marginal ridges

C. Cusp tips

D. All of the above

The correct answer is B. Marginal ridges.

The oblique ridge is a ridge that crosses the occlusal surface obliquely. The union of the triangular ridge of the distobuccal cusp and the distal ridge of the mesiolingual cusp forms it. This ridge is reduced in height in the center of the occlusal surface, being about on a level with the marginal ridges of the occlusal surface. Sometimes it is crossed by a developmental groove that partially joins the two major fossae by means of its shallow sulcate groove.

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Which Premolar develops from five lobes?

  # Which of the following premolars develop from five lobes?

A. Maxillary first premolar

B. Maxillary second premolar

C. Mandibular first premolar

D. Mandibular second premolar

The correct answer is D. Mandibular second premolar.

The mandibular first premolars are developed from four lobes, as were the maxillary premolars. The mandibular second premolars are, in most instances, developed from five lobes, three buccal and two lingual lobes.

Reference: Wheeler's, 10th Edition, Page 151