Which of the following is indicative of ageing?

 # Which of the following is indicative of ageing?

A. Expression of dead tracts

B. Widening of predentin

C. Increase in tubular diameter

D. Increase in peritubular dentin

The correct answer is A. Expression of dead tracts. 

It is rather difficult to separate age and functional changes in dentin. Dentin is laid down throughout life. This dentin is termed secondary dentin. If dentin forms as a result of pathological process, like caries, it is termed tertiary dentin. Tertiary dentin shows irregularity in size, shape, number and arrangement of dentinal tubules. Dentinal tubules degenerate due to injury resulting in the formation of dead tracts. Mineralization of dentinal tubules results in the formation of sclerotic dentin. This makes the tooth to appear transparent in these areas.

Reference: Orban's Oral Histology and Embryology

The formation of hard tissue takes place in the:

 # The formation of hard tissue takes place in the:

A. Bud stage

B. Cap stage

C. Advanced bell stage

D. Early bell stage

The correct answer is C. Advanced bell stage.

Advanced bell stage is characterized by the commencement of mineralization and root formation. During the advanced bell stage, the boundary between inner enamel epithelium and odontoblasts outlines the future dentinoenamel junction. The formation of dentin occurs first as a layer along the future dentinoenamel junction in the region of future cusps and proceeds pulpally and apically.

Reference: Orban's Oral Histology and Embryology, 14th Edition

Paget’s test is done in the examination of

 # Paget’s test is done in the examination of:

A. A small swelling

B. Serum calcium

C. Urine analysis for alkaline phosphatase

D. Cytologic smear

The correct answer is A. A small swelling.

Paget's test is done for small swellings to know the consistency (cystic/solid). The centre and peripheries are palpated with index finger. Cystic swelling feels softer at centre than periphery whereas solid swelling feels firmer at center than periphery.

Which of the following is a general property of biofilms?

 # Which of the following is a general property of biofilms? 

a. Susceptible to host defenses. 

b. Limited habitat range. 

c. Open architecture.

d. Reduced virulence

The correct answer is C. Open architecture.

The close relationships between the architecture of a biofilm and its functional properties emphasizes the need to better describe and understand cell behavior, from single cell to multicellular scale, during biofilm structure development and maturation. Recent technological advances in methodologies including imaging and microscopy, molecular techniques, and physico-chemical assays, enabled the development of novel approaches dedicated to biofilm studies (Azeredo et al., 2017). The possibility to observe biofilm using high resolution and non-destructive methods now allows investigating the dynamics of multicellular structure development and the fate of each of its individual cellular components in parallel. For instance, the key architectural transitions and associated biophysical and genetic mechanisms supporting the developmental program of Vibrio cholerae biofilms have been recently disclosed using single-cell live imaging (Drescher et al., 2016; Yan et al., 2016). This kind of observations has clearly improved our understanding of spatio-temporal development of biofilms and has finally increasingly supported the intimate connection between structural modulations and the emergence of functional features and survival strategies. Indeed, the ability of biofilms to adapt their structure in response to internal or external stimuli, called hereafter the architectural plasticity, appears as a key factor affecting the fitness of individuals within the whole microbial community. Interestingly, the role of plasticity in bacterial survival was already demonstrated at the cellular scale. Bacteria are able to alter their morphology and to produce specific morphotypes conferring survival advantages in hostile environments. This was showed for numbers of bacterial pathogens for which filamentation is essential in the resistance to phagocytosis and overall for persistence during infection. 

Reference: https://www.frontiersin.org/articles/10.3389/fmicb.2017.01364/full

Boiling point of methyl methacrylate is:

# Boiling point of methyl methacrylate is:

A. Greater than B.P of water 

B. Lesser than B.P of water 

C. Equal to BP of water 

D. Is at normal room temperature 

The correct answer is A. Greater than Boiling Point of Water. 

Methyl methacrylate (MMA) is an organic compound with the formula CH2=C(CH3)COOCH3. This colorless liquid, the methyl ester of methacrylic acid (MAA), is a monomer produced on a large scale for the production of poly(methyl methacrylate) (PMMA).

Melting point : −48 °C (−54 °F; 225 K)

Boiling point : 101 °C (214 °F; 374 K)

Flow of Oxygen in Oxygen flush system

 # The oxygen flush system provides a higher flow of oxygen of ________ L/min when the patient’s need for oxygen is greater than the amount the breathing circuit can provide. 

a) 25-50 

b) 35-75 

c) 55-95 

d) 65-105 

The correct answer is B. 35-75.

Many anesthesia providers use the oxygen flush valve daily especially in those cases where the face mask fit is not optimal during the induction. When an emergency occurs it is comforting to know where a supply of oxygen is readily located, how much can be delivered, and that a flow is available despite the anesthesia being lifted on or off.

The oxygen flush can be used even when the anesthesia machine is not turned on and will operate in its regular fashion. It delivers oxygen straight from the pipeline or cylinder regulator at 45-50 psig (Pounds per square in gauge). The flow rate will be between 35-75 L/min. 

Acetone breath is a feature of:

 # Acetone breath is a feature of:

A. Sinusitis

B. Renal disease

C. Liver disease

D. Diabetes mellitus

The correct answer is D. Diabetes mellitus.

Diabetic ketoacidosis (DKA) is a potentially life-threatening complication of diabetes mellitus. Signs and symptoms may include vomiting, abdominal pain, deep gasping breathing, increased urination, weakness, confusion and occasionally loss of consciousness. A person's breath may develop a specific "fruity" smell. Onset of symptoms is usually rapid. People without a previous diagnosis of diabetes may develop DKA as the first obvious symptom.

DKA happens most often in those with type 1 diabetes but can also occur in those with other types of diabetes under certain circumstances. Triggers may include infection, not taking insulin correctly, stroke and certain medications such as steroids. DKA results from a shortage of insulin; in response, the body switches to burning fatty acids, which produces acidic ketone bodies. DKA is typically diagnosed when testing finds high blood sugar, low blood pH and ketoacids in either the blood or urine.

On physical examination there is usually clinical evidence of dehydration, such as a dry mouth and decreased skin turgor. If the dehydration is profound enough to cause a decrease in the circulating blood volume, a rapid heart rate and low blood pressure may be observed. Often, a "ketotic" odor is present, which is often described as "fruity" or like "pear drops". The smell is due to the presence of acetone. If Kussmaul respiration is present, this is reflected in an increased respiratory rate.

Small children with DKA are relatively prone to brain swelling, also called cerebral edema, which may cause headache, coma, loss of the pupillary light reflex, and can progress to death. It occurs in about 1 out of 100 children with DKA and more rarely occurs in adults.