Dentosphere : World of Dentistry

The spontaneous production of an electric current resulting from two dissimilar metals in the oral cavity is called:

A. Nuclear reaction

B. Galvanic action

C. Precipitation reaction

D. Thermodynamics

The correct answer is B. Galvanic action

Galvanic action, also known as oral galvanism, occurs when two dissimilar metals in the oral cavity contact saliva (an electrolyte), forming a battery-like setup that generates a spontaneous electric current. This can cause symptoms like metallic taste, pain, or tissue irritation. Studies and dental resources confirm this electrochemical process is specific to bimetallic interactions in the mouth, distinguishing it from unrelated options: nuclear reactions (subatomic), precipitation (ion formation), and thermodynamics (energy principles).

Which of the following materials has been shown to stimulate reparative dentine formation most effectively when applied to the pulpal wall of a very deep cavity?

# Which of the following materials has been shown to stimulate reparative dentine formation most effectively when applied to the pulpal wall of a very deep cavity?

A. Copalite varnish

B. Calcium hydroxide preparation

C. Zinc phosphate cement

D. Anhydrous glass ionomer cement

The correct answer is B. Calcium hydroxide preparation

Calcium hydroxide has been established as the gold standard for stimulating reparative dentin formation in deep cavities near the pulp. It promotes odontoblast differentiation and dentin bridge formation by releasing calcium ions, which enhance fibronectin expression and mineralization. Studies, including clinical reviews, show success rates of around 83% for indirect pulp capping with calcium hydroxide.

In comparison:

A. Copalite varnish: Acts as a protective liner to reduce irritation but does not induce reparative dentin.
C. Zinc phosphate cement: Provides thermal insulation as a base but lacks bioactive properties for dentin stimulation.
D. Anhydrous glass ionomer cement: Offers fluoride release and bonding but is less effective than calcium hydroxide for reparative dentin; modified versions may help, but standard types do not match its inductive capacity.

Dr. Raman Dhungel, BDS (BPKIHS), MDS Resident Department of Orthodontics, BPKIHS Dharan Contact Number

If you need to arrange / reschedule any appointment with Dr. Raman Dhungel, BDS (BPKIHS), MDS Resident Department of Orthodontics, BPKIHS Dharan, then you can message on Whatsapp (+9779803027654) or call on +9779803027654/+9779849510059. Call only when absolutely necessary and preferably at 6:00 PM to 8:00 PM.

Difference in the amount of space needed for the accommodation of the incisors and amount of space available for them is known as:

A. Primate space

B. Leeway Space of Nance

C. Anthropoid space

D. Incisal liability

Incisal liability, also known as incisor liability, describes the space discrepancy in the mixed dentition phase where the permanent incisors require more mesiodistal width (typically 7 mm in the maxillary arch and 5 mm in the mandibular arch) than the primary incisors they replace, creating a potential crowding issue that must be accommodated by factors like interdental spacing, arch perimeter changes, or leeway space. This is distinct from primate space (A, developmental space distal to the lateral incisor), leeway space of Nance (B, difference between deciduous and permanent molars/canines), and anthropoid space (C, a less common term sometimes used interchangeably with primate space in non-human primates).

Type of crowding that is genetically determined and is caused by disproportionately sized teeth and jaws:

A. Primary crowding

B. Secondary crowding

C. Tertiary crowding

D. Environmental crowding

The correct answer is A. Primary crowding.

Primary crowding refers to a type of dental crowding caused by a genetic discrepancy in tooth and jaw sizes, such as larger teeth relative to the jaw, leading to misalignment. This contrasts with secondary crowding, which results from environmental factors like early tooth loss, and tertiary crowding, which involves late-stage incisor irregularities. Environmental crowding isn't a standard classification but aligns with secondary causes.

Which of the following is the least biocompatible?

A. TMA

B. Elgiloy

C. Stainless steel

D. Cu-NiTi

The correct answer is B. Elgiloy.

Elgiloy (a cobalt-chromium-nickel alloy) is the least biocompatible among the options due to its higher nickel content (14-16%) compared to stainless steel (8%), leading to greater nickel and chromium ion release in simulated oral environments. Studies show it induces significant neurotoxicity via necrosis, elevated oxidative stress, and higher cytotoxicity (2.7-fold increase in dead cells) relative to stainless steel (apoptosis, 1.7-fold dead cells), TMA (variable but generally low ion release and non-toxic), and Cu-NiTi (lower ion release and minimal cytotoxicity). This increases risks of allergic reactions and tissue irritation in orthodontic use.

What is facial divergence?

# What is facial divergence?

A. Relation of maxilla to mandible

B. Lower face inclination in relation to the forehead

C. Relation of mandible to forehead

D. Relation of lower face with cranial base

The correct answer is B. Lower face inclination in relation to the forehead

Examination of facial divergence is done by viewing the patient from the side. Facial divergence is often influenced by patient’s ethnicity and racial background. For instance, convex profile with an anterior facial divergence is a normal feature of negroid race groups. Facial divergence is defined as an anterior or posterior inclination of mandible (lower face) relative to the forehead. Assessment of facial divergence is done by a line drawn from the forehead to the chin. Facial divergence of an individual may fall into any one of the following three types: 1. Straight/orthognathic—A line drawn from forehead to chin is almost straight. 2. Anterior facial divergence—The line drawn from forehead to the chin is inclined anteriorly. 3. Posterior facial divergence—The line drawn from forehead to the chin is inclined posteriorly.