Induction of the dental follicle is by:

  # Induction of the dental follicle is by:

A. TNF

B. BMP

C. IL1

D. CSF1

The correct answer is B. BMP.

TNF (Tumor Necrosis Factor):  TNF is primarily known as a pro-inflammatory cytokine and is not directly associated with the induction of the dental follicle. 

BMP (Bone Morphogenetic Protein): BMPs are a group of growth factors also known as cytokines and as metabologens. Among their various roles in the body, BMPs are involved in the induction of the dental follicle and play a significant role in bone development and repair. 

IL1 (Interleukin 1): IL1 is involved in inflammatory responses and is not directly associated with the induction of the dental follicle. 

CSF 1 (Colony Stimulating Factor 1): CSF 1 is primarily involved in the control of survival, proliferation, and differentiation of hematopoietic stem cells into macrophages and other related cell types, and it is not directly involved in the induction of the dental follicle. 

Hence, the correct answer is B) BMP, which is involved in the induction of the dental follicle and subsequent formation of the periodontal tissues. 



Which of the following calcified tissues have minimum lag phase between matrix formation and mineralization?

  # Which of the following calcified tissues have minimum lag phase between matrix formation and mineralization?

A. Enamel

B. Cementum

C. Bone 

D. Dentin

The correct answer is A. Enamel.

The formation of the enamel can be described as the secretory phase (primary mineralization or matrix formation) where only 30 percent is mineralized and the secondary phase or maturation characterized by the crystal growth and complete mineralization. There is no time lag between these phases and hence the mineralization of enamel is a continuous process. This is the reason why structure equivalent to that of predentin or osteoid as seen in dentin and bone is not found in enamel. 

The way mineral is introduced into the organic matrix of enamel differs from its introduction in other hard tissues. In these tissues matrix vesicles provide a closed environment to initiate crystal formation in a preformed organic matrix. No matrix vesicles are found in association with the initial mineralization of enamel protein. 



Non keratinized epithelium is found over:

  # Non keratinized epithelium is found over:

A. Attached gingiva

B. Free gingiva

C. Interdental papilla

D. Gingival sulcus

The correct answer is D. Gingival sulcus.

The gingival tissue is made up of 75% Para keratinized epithelium, about 15 % keratinized and only 10% non keratinized epithelium.

The keratinized area of the gingiva includes the attached gingiva and some portions of the outer gingival epithelium. 

The para keratinized gingiva includes the marginal gingiva and portions of the outer gingival epithelium.

The non keratinized portion of gingiva includes the gingival col, junctional epithelium and sulcular epithelium.



The gene that defines the localization of the tooth germs is:

  # The gene that defines the localization of the tooth germs is:

A. FGF-8

B. BMP-2

C. Dlx-5

D. Pax-9

The correct answer is D. Pax-9.

During tooth development, several mesenchymal molecules and their receptors act as mediators of epithelial - mesenchymal interactions. Bone morphogenetic proteins (BMPs) 2,4,7 mRNAs shift between epithelium and mesenchyme during regulation of tooth morphogenesis. Fibroblast growth factor (FGF8, FGF9) have been localized in the dental mesenchyme and act via downstream factors MSX1 and PAX9. Muscle specific homeobox genes MSX-1 and Msx-2, appear to be involved in epithelial mesencymal interactions and craniofacial development, particularly in the initiation of developmental position (Msx-1) and further development (Msx-2) of tooth buds.Pax-9 is transcription factor necessary for tooth morphogenesis.