441. Pioneer bacteria in dental caries are in_____________?
A. Enamel
B. Dentin
C. Pulp
D. Cementum

442. Chemico-parasitic theory of dental caries is proposed by______________?
A. Miller
B. G.V black
C. Gottlieb
D. Schwartz

443. In a caries-free individual the saliva has_____________?
A. low buffering capacity of acids
B. Medium buffering capacity for acids
C. High buffering capacity for acids
D. Independent of buffering capacity for acids

444. The lateral spread of dental caries is facilitated mostly by the_______________?
A. Enamel spindles
B. Dentinoenamel junction
C. Enamel lamellae
D. Striae of Retzius

445. Caries, all are true except______________?
A. Lactobacillus is main accusative organism in plaque
B. Smooth surface caries occur due to streptococcus mutans
C. Pit and Fissure caries can be prevented by using pit and tissue sealants
D. Fluorides help in reducing caries incidence

446. Initiation of dental caries depends upon_______________?
A. Formation of large amount of acid
B. Availability of carbohydrate food
C. Viscosity of saliva
D. Localization of acid over tooth surface

447. Miller put forth the acidogenic theory of dental caries in the year______________?
A. 1890
B. 1920
C. 1924
D. 1980

448. Turbid dentin in carious tooth is all EXCEPT_____________?
A. Zone of bacterial invasion
B. Zone which can not be demineralized
C. Zone in which collagen is irreversibly denatured
D. Zone that need not be removed before restoration

449. Least cariogenic among these______________?
A. Raw starch
B. Cooked starch
C. Sucrose
D. Fructose

450. In the earliest stages of carious lesion. There is loss of______________?
A. Enamel cuticle
B. Antiprismatic substance
C. Organic matrix
D. Enamel lamellae