Lec.1 Dental Materials

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Questions and Answers

What is the undesirable property of amalgam filling material for posterior teeth?

It dissolves in saliva
It has high water absorption
It expands when exposed to heavy biting force
It changes shape permanently when subjected to heavy biting force (correct)

What is the purpose of expansion in investment material for dental casting?

To increase the strength of the dental casting
To compensate for the contraction of molten metal after cooling (correct)
To improve the aesthetics of the dental restoration
To reduce the solubility of the material in water

Why is high water absorption undesirable in dental materials?

It can lead to unhygienic conditions and dimensional changes (correct)
It causes the material to change shape permanently
It leads to increased solubility of the material
It reduces the strength of the material

What is the unit of measurement for solubility of dental materials?

µg/mm² (C) Signup and view all the answers

Why is density an important consideration in restorative materials?

It affects the weight and mobility of the restoration (A) Signup and view all the answers

Match the following materials with their coefficient of thermal expansion (α) in dentistry:

Tooth = 1110-6 cm/cm°C Gold = 1410-6 cm/cm°C Impression compound = 250*10-6 cm/cm°C Signup and view all the answers

Match the following clinical importance with the correct reason:

Preventing marginal leakage = To prevent pressure on the pulp or pull away from the cavity wall Providing metal ceramic bonding = To avoid crazing of artificial tooth and denture base Maintaining 2-dimensional stability = To prevent breakage of marginal seal between the filling and the cavity wall Avoiding recurrent caries = To prevent discolouration and hypersensitivity Signup and view all the answers

Match the following materials with their coefficient of thermal expansion ranking in dentistry:

Hard tooth structure = Smallest Metals = Intermediate Polymers = Largest Signup and view all the answers

Match the following consequences with the correct cause:

Marginal leakage = Difference in coefficient of thermal expansion between tooth and restorative materials Discolouration = Poor metal ceramic bonding Recurrent caries = Crazing of artificial tooth and denture base Hypersensitivity = Breakage of marginal seal between the filling and the cavity wall Signup and view all the answers

Match the following requirements with the correct material property:

Dimensional stability = To prevent changes in shape after setting Coefficient of thermal expansion = To prevent marginal leakage and recurrent caries 2-dimensional stability = To prevent changes in shape after hardening No dimensional changes after setting = To prevent breakage of marginal seal between the filling and the cavity wall Signup and view all the answers

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