Radiographically, driven snow appearance is seen with:

# Radiographically, driven snow appearance is seen with:
A. Adenomatoid odontogenic tumor
B. Calcifying odontogenic cyst
C. Calcifying epithelial odontogenic tumor
D. Keratocyst

The correct answer is C. Calcifying Epithelial Odontogenic Tumor

- Scattered flecks of calcification throughout the radiolucency has given rise to the descriptive term driven snow appearance.

- Lesion appears as diffuse or well circumscribed unilocular radiolucency.

- Combined radiolucency and radioopacity with irregular bony spicules producing honeycomb pattern

- Scattered flecks of calcification give driven snow appearance

- Sometimes, lesion is totally radiolucent and in association with unerupted tooth

Zones of Dentinal Caries

ZONES OF DENTINAL CARIES
ZONE 1	Normal Dentin
Zone 2	Subtransarent Dentin	Zone of demineralization (by acid from caries) Damage to the odontoblastic process is evident. However, no bacteria are found in the zone. Stimulation of the dentin produces pain, and the dentin is capable of remineralization.
Zone 3	Transparent dentin	Softer than normal dentin Further loss of mineral from the intertubular area. Stimulation of this region produces pain. There are no bacteria present. The collagen cross-linking remains intact in this zone, can serve as a template for remineralization. The intact collagen of the intertubular dentin, and thus this region remains capable of self-repair, provided the pulp remains vital.
Zone 4	Turbid dentin	Turbid dentin is the zone of bacterial invasion  Widening and distortion of the dentinal tubules which are filled with bacteria. There is very little mineral present and the collagen in this zone is irreversibly denatured. The dentin in this zone will not self-repair. This zone cannot be remineralized and must be removed prior to restoration
Zone 5	Infected Dentin	The outermost zone, infected dentin, consists of decomposed dentin that is teeming with bacteria. There is no recognizable structure to the dentin. Absence of collagen and mineral content. Great numbers of bacteria are dispersed in this granular material. Removal of infected dentin is essential to sound, successful restorative procedures as well as prevention of spread of the infection

# Whenever the caries cone in enamel is larger or at least the same size as that in dentin, it is called as:

# Whenever the caries cone in enamel is larger or at least the same size as that in dentin, it is called as:
A. Residual caries
B. Recurrent caries
C. Forward caries
D. Backward caries

Forward Caries. Forward caries is where the caries cone in enamel is larger or at least the same size as that in dentin.

Backward Caries. When the spread of caries along the DEJ exceeds the caries in the contiguous enamel, caries extends into this enamel from the junction.

Ans is C: Forward caries (Ref: Sturdevant's Art and science of operative dentistry 4th ed., p 274)

# DPT vaccine does not provide immunity against:

# DPT vaccine does not provide immunity against:
A. Tetanus
B. Diphtheria
C. Polio
D. Whooping cough

The correct answer is C. Polio.

The vaccine DPT stands for Diphtheria, Pertusis (Whooping cough) and Tetanus.