# Dens in dente is most commonly seen in:

  # Dens in dente is most commonly seen in:

A. Premolars

B. Paramolars

C. Lateral incisors

D. Maxillary canine

The correct answer is C. Lateral incisors.

Also known as dens in dente or tooth within a tooth, dens invaginatus is an uncommon tooth anomaly that represents an exaggeration or accentuation of the lingual pit.

This defect ranges in severity from superficial, in which only the crown is affected, to deep, in which both the crown and the root are involved. The permanent maxillary lateral incisors are most commonly involved, although any anterior tooth may be affected. Bilateral involvement is commonly seen. The cause of this developmental condition is unknown. Genetic factors are believed to be involved in only a small percentage of cases.

Dens evaginatus is a relatively common developmental condition affecting predominantly premolar teeth (Leung’s premolars).

Reference: Regezi, Sciubba, Jordan; Oral Pathoogy: Clinical Pathologic correlations.



Prolonged administration of broad spectrum antibiotics results in the formation of:

  # Prolonged administration of broad spectrum antibiotics results in the formation of:

A. Black Hairy tongue

B. Median rhomboid glossitis

C. Geographic tongue

D. Fissured tongue

The correct answer is A. Black Hairy tongue.

Numerous initiating or predisposing factors for hairy tongue have been identified. Broad-spectrum antibiotics and systemic corticosteroids are often identified in the clinical history of patients with this condition. In addition, oxygenating mouth rinses containing hydrogen peroxide, sodium perborate, and carbamide peroxide have been cited as possible etiologic agents in this condition. Hairy tongue may also be seen in individuals who are heavy smokers, in those who have undergone radiotherapy to the head and neck region for malignant disease, and in patients who have undergone hematopoietic stem cell transplantation. The basic problem is believed to be related to an alteration in microbial flora, with attendant proliferation of fungi and chromogenic bacteria, along with papillary overgrowth.

Reference: Oral Pathology: Clinical Pathologic Correlations, Regezi, Sciubba, Jordan



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. 



Salivary gland aplasia is seen in:

 Salivary gland aplasia is seen in:

A. Hemifacial microsomia

B. LADD syndrome

C. Mandibulofacial dysostosis (Treacher Collins)

D. All of the above

The correct answer is D. All of the above.

Aplasia occurs for unknown reasons as an isolated finding or in conjunction with other developmental defects such as hemifacial microsomia, the LADD syndrome and mandibulo-facial dysostosis (Treacher Collins). In the more severe cases, the ensuing xerostomia causes clinical problems. Salivary loss leads to increased caries, burning sensations, oral infections, taste aberrations and difficulty with denture retention.