‘Choking off’ phenomenon takes place after application of:

 # ‘Choking off’ phenomenon takes place after application of:

A. APF

B. NaF

C. SnF2

D. Amine Fluoride

The correct answer is B. NaF.

Choking off phenomenon is seen with the application of sodium fluoride varnish.

Neutral Sodium Fluoride 

• Fluoride concentration = 9200 ppm 

• Formed by dissolving 20 gms NaF in 1 Litre of water in a plastic bottle 

• Knutson technique: used for NaF application - Clean and dry teeth and isolate the field - Apply 2% NaF over teeth with cotton bud/applicator. Allow the solution to dry for 3-4 minutes - Application is repeated at 2nd, 3rd and 4th week at an interval of 1 week each. These applications are not preceded by Scaling. - The four-visit procedure is recommended for age groups 3, 7, 11, 13 years coinciding with eruption of different dentitions 

• Mechanism of action - NaF applied to tooth surface reacts with tooth calcium to form CaF2 - As CaF2 develops, it impedes further penetration of fluoride into hydroxyapatite. This is called "Choking off" phenomenon. It is because of this phenomenon, repeated application of NaF should be done only after 4 minutes. - The CaF2 reacts with hydroxyapatite to slowly release fluoride and thus is caries inhibitory. 

• Advantages: 

- NaF is stable when kept in plastic containers. NaF reacts with glass 

- Taste is well acceptable by patient 

- Does not discolour tooth structure 

- Procedure indicated only at specific ages and not every year application 

• Disadvantages: - At the index age, 4 visits to the dentist are mandatory in that year. 

Raloxifene is used in the treatment of:

 # Raloxifene is used in the treatment of:

A. Renal osteodystrophy

B. Post menopausal osteoporosis

C. Chronic renal failure

D. Chronic osteomyelitis

The correct answer is B. Post menopausal osteoporosis. 

Raloxifene is used by women to prevent and treat bone loss (osteoporosis) after menopause. 

Raloxifene belongs to a group of drugs called Selective Estrogen Receptor Modulators (SERMs). It is a Second- generation agent. 

The principal use of Raloxifene is in the management of Post-menopausal Osteoporosis. It is also useful in Hormone sensitive Breast cancer (both prevention and treatment). 

It is important to remember that SERMs are partial Estrogen receptor antagonists. Raloxifene inhibits the estrogen receptors in breast while stimulates those in Bone marrow. Thus, it has tissue selective action which reduces the toxicity. Like Tamoxifen, it also lowers LDL cholesterol and thus has a favorable lipid profile. Side effects include hot flushes and calf pain (like Tamoxifen, but less incidence and severity). 

In contrast, Tamoxifen is a Pure Estrogen Receptor antagonist (1st Generation SERM). It causes significant side effects including Intravascular clotting, post-menopause like symptoms, hot flushes, calf pain, uterine bleeding, Uterine Carcinoma and Polyps. Its current use is limited to Management of Estrogen Sensitive Breast cancer. 

Third-generation drug, Bazedoxifene, has also been developed to treat osteoporosis and has similar effects to that of raloxifene. 

Apart from Raloxifene, Bisphosphonates, calcium supplements and Vitamin D supplements are used for management of post-menopausal Osteoporosis. 

Which of the following acts as an astringent?

 # Which of the following acts as an astringent?

A. Thymol

B. Glycerin

C. Zinc chloride

D. Liquoron

The correct answer is C. Zinc chloride.

Zinc chloride is a commonly known astringent used in various ways as in with retraction cords, gum paints and for management of oral ulcers. 

• Astringents : These are substances that act by precipitating proteins on the superficial layer of mucosa and make it mechanically stronger. Examples are alum or aluminum potassium sulfate (KAl (SO4)2), A1C13 and zinc chloride (ZnC12) 

• Styptics: These are concentrated forms of astringents, which cause superficial and local coagulation. Examples are ferric chloride and ferric sulfate (Fe2 (SO4)3) 

• A1C13 and ferrous sulfate are preferred astringents among dentists because of minimum tissue damage. 

• Because of the caustic action of zinc chloride on the oral tissues, it is not the preferred chemical for gingival retraction although it is still used for management of oral ulcers. 

Which of the following is an opsonin?

 # Which of the following is an opsonin?

A. C3b

B. C3a

C. IgG

D. IgA

The correct answer is A. C3b.

Opsonization is the process of increasing ability for phagocytosis of foreign body. In opsonisation, opsonin antibodies attach to the bacteria and facilitate the phagocytosis of that bacterium. 

Different types of opsonins: 

• Antibodies- IgM and IgG 

• Complement proteins- C3b, C4b 

• Circulating proteins- Pentraxins, collectins, and ficolins 

Origin of tongue muscles:

 # Origin of tongue muscles:

A. Occipital myotome

B. First pharyngeal swellings

C. Lateral lingual swellings

D. Pre optic myotomes muscles

The correct answer is A. Occipital myotome.

All muscles of tongue both intrinsic and extrinsic except palatoglossus are derived from the four occipital myotomes and are supplied by 12th cranial nerve (which is formed by fusion of pre cervical nerves) and the palatoglossus is supplied by vagus nerve. The occipital myotomes migrate into the developing tongue (contributed by 1st to 3rd pharyngeal arches) in the floor of mouth. Muscles develop from occipital myotomes supplied by hypoglossal nerve. 

The characteristic alarm clock headache is a feature of:

 # The characteristic alarm clock headache is a feature of:

A. Auriculotemporal neuralgia

B. Trigeminal neuralgia

C. Sphenopalatine neuralgia

D. Glossopharyngeal neuralgia

The correct answer is C. Sphenopalatine neuralgia.

Sphenopalatine neuralgia / Lower half Headache / Sluder's headache / Horton's syndrome

• Described by Sudian, who concluded the involvement of Vidian nerve. 

• Pain is thought to be generated at the level of pericarotid or cavernous sinus complex. 

• Characterized by unilateral paroxysms of pain in the region of eyes; the maxilla, the ear and mastoid, and beneath the zygoma. 

• There is no trigger zone. 

• Unfortunately, the attacks develop regularly, usually atleast once a day, over a prolonged period of time. 

• Interestingly in some patients, the onset occurs at exactly the same time of day, because of which it is referred to as alarm clock headache 

Application of fluoride varnish after luting a crown has which of the following beneficial action?

 # Application of fluoride varnish after luting a crown has which of the following beneficial action?

A. Removes fluorides from enamel

B. Reduces the peripheral seal

C. Provides desensitizing action

D. Allows dissolution of marginal cement

The correct answer is C. Provides desensitizing action.

Fluoride applied after crown cementation has the benefit of reducing the decalcification in the area and helps to seal the tubules which may be open at the cervical tooth margin. This provides for additional desensitizing action.