Bacteria found in two days old plaque is:

# Predominant bacteria found in two days old plaque is:
A. Streptococci
B. Bacteroides
C. Spirochetes
D. Actinomyces

The correct answer is: A. Streptococci. 

- Plaque can be defined as a complex microbial community, with greater than 10^10 bacteria per milligram. 

- The formation of pellicle is the first step in plaque formation.

- "Primary colonizers" : The pellicle coated tooth surface is colonized by Gram- Positive aerobic cocci bacteria such as Streptococcus sanguis, Streptococcus mutans, and Actinomyces viscous. 

- Secondary colonizers: After 1 to 3 days, the secondary colonizers are gram negative anerobic rods and filaments that include Fusobacterium nucleatum, Prevotella intermedia, and Capnocytophaga species. 

Tertiary colonizers: After one week of plaque accumulation, other gram negative species may also be present in plaque. They include Porphyromonas gingivalis, Campylobacter rectus, Eikenella corrodens, Actinobacillus actinomycetemcomitans, and the oral spirochetes (Treponema species).

- The structural characteristics of dental plaque in this time period reveal complex patterns of bacterial cells of cocci, rods, fusiform, filaments, and spirochetes. 

- Particular specific associations of different bacterial forms have been observed . For example, the adherence of cocci to filaments results in a typical form referred to as "test tube brushes" or "corn cob" arrays. 

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Storiform pattern of fibrous tissue

# Storiform pattern of fibrous tissue is seen in:
a. Fibrosarcoma
b. Malignant fibrous histiocytoma
c. Neurofibroma
d. Ameloblastic fibroma

The correct answer is: B. Malignant fibrous histiocytoma.

MALIGNANT FIBROUS HISTIOCYTOMAS
- are group of aggressive malignant neoplasms, arising from undifferentiated mesenchymal cells that differentiate along both fibroblastic and histiocyte pathways.
- Histologically the neoplasm reveals actively proliferating, numerous polyhedral or oval shaped, malignant histiocytes and many spindle shaped malignant fibrous cells.
- These malignant cells are often arranged in a typical "Cart-wheel" or "Storiform" pattern or Criss cross.
- Fibrous histiocytoma: Storiform pattern (helicopter in wheat field) is seen.

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Oral Drive Theory

# The oral drive theory to explain thumb sucking habit was given by:
a) Benjamin
b) Sears and wise
c) Sigmund Freud
d) Scheldon

The correct answer is B. Sears and Wise.

According to ORAL DRIVE THEORY OF SEARS AND WISE, prolonged suckling lead to thumb sucking.

BENJAMIN'S TH EORY states that thumb sucking arises from the rooting or placing reflex. Rooting reflex is the movement of infant's head and tongue towards an object touching his cheek. The rooting reflex disappears in normal infants around 7-8 months of age.

According to SIGMOND FREUDIAN THEORY, in the oral phase of psychologic development, the mouth is believed to be an oro-erotic zone. The child has the tendency to place fingers or any other object into the oral cavity.

ORAL GRATIFICATION THEORY BY SHELDON states that if a child is not satisfied with sucking during the feeding period it will persist as a symptom of an emotional disturbance by digit sucking.

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Gonial angle at birth

# The gonial angle at birth is?
a) 110°
b) 115°
c) 175°
d) 145°

The correct answer is D. 145 degrees.

 The mandibular or gonial angle during perinatal period ranges from 135° to 150°; however, soon after birth, it decreases to 130° to 140°. In adult mandible, the gonial angle measures between 110° to 120°. Studies have also indicated that the angle value of females is 3-5° greater than that of males.

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