Cleansable dentin

# Slow caries leading to formation of black, hard, cleansable dentin is called as:
 A. Reparative dentin
 B. Secondary dentin
 C. Eburnated dentin
 D. Arrested dentin

The correct answer is C. Eburnated Dentin.

An arrested dentinal lesion typically is 'open', dark and hard, and this dentin is termed as sclerotic or eburnated dentin.

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Root caries of tooth

# Root caries is alarming because:
 A. It is near to apex
 B. It is symptomatic
 C. It is not seen
 D. It has rapid progression

The correct answer is D. It has rapid progression.

- Root surface caries may occur on the tooth root that has been exposed to the oral environment.
- Root caries is usually more rapid than other forms of caries, and thus should be detected and treated early.
- Root caries is becoming more prevalent because an increasing number of older persons are retaining more of their teeth and experiencing gingival recession, both of which increase the likelihood of root caries development.

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Remineralization of Tooth

# The pH at which the remineralisation of damaged tooth structure occurs is said to be:
 A. 5.5
 B. 2.5
 C. 3.5
 D. 6.2

The correct answer is A. 5.5.

5.5 for 20 to 50 minutes is called as critical pH below which the tooth demineralizes and above remineralization occurs.

The critical pH for root surface demineralization is approximately 6 to 6.7

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Absolute Contraindication for extraction of teeth

# An absolute contraindication for extraction of teeth is:
A. Hypertension
B. Myocardial infarction
C. Thyrotoxicosis
D. Central hemangioma 

The correct answer is D. Central hemangioma.

Hemorrhagic lesions: There are two entities that constitute absolute contraindications to exodontics: arteriovenous or sinusoidal aneurysms and central hemangiomas. (KRUGER)

Extraction of a tooth associated with a central hemangioma results in profuse bleeding and death of patients.

Relative contraindications:
- six months after a myocardial infarction
- extraction of teeth in previously irradiated areas
- presence or suspicion of hemangioma
- uncontrolled diabetes mellitus
- acute blood dyscrasias
- untreated coagulopathies
- necrotizing ulcerative gingivitis
- Adrenal insufficiency
- Thyrotoxicosis

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