MCQs on Dental Materials : Amalgams Part 3

# A true eutectic alloy has melting point:
A. Above that of the low fusing metal
B. above the melting point of either metal
C. Below that of the high fusing metal
D. Below the melting point of either metal

# Creep value of which of the following is the highest ?
A. Low copper amalgam alloy
B. Admix alloy
C. Single composition alloys
D. Creep value of all the above mentioned alloys is same

# Advantages of minimum mercury technique or Eames technique is all except:
A. High strength
B. Sets quickly
C. Needs no squeezing of excess mercury
D. Greater plasticity and adapts well to cavity walls

# Amalgam achieves 70% of the strength by:
A. 2 hours
B. 4 hours
C. 8 hours
D. 16 hours

# The solid solution of silver and mercury is called:
A. gamma 1
B. gamma 2
C. beta 1
D. gamma

# Mercury is toxic because it:
A. complexes hemoglobin to form methemoglobin
B. inhibits hemoglobin synthesis, producing anemia
C. inhibits aerobic glycolysis
D. binds to sulfhydryl groups

# Once triturated, the dentqal amalgam should be condensed within:
A. 5 minutes
B. 6 minutes
C. 3 minutes
D. 15 minutes

# What fraction of inhaled mercury vapors is retained in the body?
A. 45-55%
B. 55-65%
C. 65-85%
D. More than 85%

# High strength amalgam is achieved by:
A. Maximum matrix amd minimum alloy phase
B. Minimum matrix and maximum alloy phase
C. Maximum matrix phase
D. Minimum alloy phase

# The effect of trituration on strength in an amalgam restoration depends on:
A. Amalgam alloy
B. Trituration time
C. Speed of amalgamator
D. All of the above




# Which of the following does not occur in high copper amalgam ?
A. Electrochemical corrosion
B. Chemical corrosion
C. Penetrating corrosion
D. Corrosion does not occur at all

# Decrease in creep occurs in:
A. Under trituration or over trituration of amalgam
B. Decrease with condensation pressure
C. Increase with condensation pressure
D. Cannot be predictable

# For dental amalgam, the elastic modulus and tensile strength is:
A. 40 Gpa and 60-100 Mpa
B. 21 Gpa and 27-55 Mpa
C. 350 Gpa and 10-120 Mpa
D. 360 Gpa and 125-130 Mpa

# Cavo surface angle for amlagam restoration is butt joint as:
A. it increases compressive and tensile strengths
B. it decreases compressive and increases tensile strength
C. it decreases both compressive and tensile strength
D. it increases compressive and decreases tensile strength

# Adequete mixing of mercury is indicated by :
A. Dry mix
B. Shiny mix
C. Short mixing time
D. None

# Which of the following are characteristic feature of high copper amalgam alloy?
A. Low compressive strength
B. High marginal breakdown
C. Less marginal breakdown
D. High creep

# Which is true regarding lathe cut silver alloy?
A. Requires least amount of mercury
B. Achieves lowest compressive strength at 1 hour
C. Has tensile strength both at 15 min and 7 days comparable to high copper unicompositional alloy
D. has low creep

# Coefficient of thermal expansion of amalgam is :
A. 6.6 ppm/K
B. 11.4 ppm/K
C. 14.0 ppm/K
D. 25.0 ppm/K

# Gallium and Indium added to amalgam replace:
A. Silver
B. Tin
C. Mercury
D. Zinc

# A patient who has had a recent amalgam filling in the upper teeth has a gold filling in the lower teeth, the patient complains of pain. The reason for this can be mainly:
A. Improper amalgam filling
B. Pulp exposure
C. Galvanism
D. None of the above

# Which one of the following is not an objective of trituration?
A. Remove oxides from powder particle surface
B. Keep the amount of gamma 1 or gamma 2 matrix crystals to maximum
C. Pulverize pellets into particles to aid in attack by mercury
D. Achieve a workable mass of amalgam in minimum time

# Outstanding clinical performance of dental amalgam restoration is related to its:
A. Compressive strength
B. Tensile strength
C. Corrosion resistance
D. High Creep

# Eames technique is ptherwise known as:
A. No squeeze cloth technique
B. Increasing dryness technique
C. Bloting mix
D. Mortar and pestle mix

# Discoloration of Ag containing alloy is due to : (Two answers correct)
A. Wet corrosion
B. Dry corrosion
C. Tarnish
D. Both Tarnish and corrosion

<< VIEW PART 2        PRACTICE MORE MCQS >>

MCQs on Dental Materials : Amalgams Part 2

# Advantage of zinc containing amalgam is :
A. Better handling property
B. Dimensional stability
C. Resistance to creep
D. Toxicity to pulp and dentin

# Cause of expansion in zinc containing amalgam is :
A. Zinc and water
B. Water
C. Hydrogen
D. Nascent oxygen

# What is the working time of amalgam ?
A. One to two minutes
B. Three to four minutes
C. Five to six minutes
D. Seven to eight minutes

# Which of the following amalgam alloys is least susceptible to creep ?
A. Lathe cut
B. Spherical
C. Microfine
D. Dispersion with high copper

# The percentage of copper in high copper alloy is :
A. 10-12%
B. 0-6%
C. 13-30%
D. 20-30%

# How soon after a moisture contamination does a zinc containing amalgam alloy start expanding ?
A. 24 hrs
B. 1-2 days
C. 3-5 days
D. 7 days

# What is common in amalgam and ceramics?
A. More compressive strength but less tensile strength
B. More compressive strength and tensile strength
C. Less compressive strength but more tensile strength
D. Less compressive strength and tensile strength

# What is the most frequeently used restorative material?
A. Silicate
B. Amalgam
C. Composite
D. Gold

# Which of the following constituents of amalgam alloy decreases expansion?
A. Copper
B. Zinc
C. Silver
D. Tin

# Which of the following silver amalgam alloys have the maximum strength ?
A. Lathe cut
B. Spherical
C. Admixed
D. Single composition

# The higher the Hg alloy ratio in dental amalgam:
A. Higher the strength
B. Lower the creep value
C. More matrix material formed
D. More gamma 1 phase formed





# Copper content in low copper amalgams is :
A. 6%
B. 12-30%
C. 29%
D. 19%

# Ag-Cu eutectic alloy has a characteristic property of that fusion temperature of :
A. the resultant alloy is greater
B. the resultant alloy is lesser
C. the resultant alloy varies according to the content of Ag and Cu
D. None

# Which phase provides maximum strength in hardened mercury/silver alloy ?
A. Silver/Mercury phase
B. Silver/Tin phase
C. Tin/Mercury phase
D. Zinc/Mercury phase

# Absorption of mercury in the human body occurs least from:
A. Lungs
B. Gastrointestinal tract
C. Skin
D. Kidneys

# The tarnished layer of silver amalgam consists of :
A. Sulphides of silver
B. Oxides of tin
C. Chlorides of tin
D. All of the above

# Which is not true about high copper amalgam alloys ?
A. Low tensile and compressive strength
B. Low Hg:alloy ratio
C. High tensile strength
D. Low creep

# The threshold limit value of mercury exposures is :
A. 0.01 mg/m3
B. 0.05 mg/m3
C. 0.1 mg/m3
D. 0.001 mg/m3

# "Amalgam" means :
A. A metallic powder composed of silver, tin, copper and zinc
B. An alloy of two or more metals, one of which is mercury
C. An alloy of two or more metals that have been dissolved in each other in the molten state
D. A metallic substance in powder or tablet form that is mixed with mercury

# Mercury intoxication in dental office mainly results from :
A. Direct contact with mercury
B. Inhalation of mercury vapours
C. Ingestion of mercury
D. None of the above

# In amalgam alloy, which of following acts as oxygen scavenger?
A. Cu
B. Zn
C. Pd
D. Ag

# Over-trituration of silver alloy and mercury:
A. reduces contraction
B. increases the strength of lathe-cut alloy but reduces the strength of spherical alloy amalgam
C. decreases creep
D. gives a dull and crumbly amalgam

# By increasing the percentage of which metal, the strength and hardness of amalgam increases?
A. Ag
B. Zn
C. Cu
D. Hg

# Mercury rich condition in a slow setting amalgam alloy system inn a restoration results in :
A. Accelerated corrosion
B. Fracture of the restoration
C. Marginal damage
D. All of the above

# Which of the following statements is true regarding lathe cut copper silver alloy ?
A. requires least amount of mercury
B. achieves high compressive strength at 1 hr.
C. has tensile strength, both at 15 minutes and 7 days is comparable to high copper, unicompositional alloys
D. has lower creep value

<< VIEW PART 1        VIEW PART 3 >>

MCQs on Dental Materials : Amalgams Part 1

# The term "trituration" means :
A. Lysing amalgam alloy
B. Mixing of amalgam alloy and mercury
C. Removal of excess of mercury
D. None of the above

# Dynamic creep is the:
A. Continuing alloying between Silver-Tin alloy and mercury during the life of the restoration
B. Deformation of set amalgam during function
C. Process whereby alloy is wetted by mercury
D. Spread of amalgam during packing

Tooth Sensitivity / Dentin Hypersensitivity

Introduction
The Canadian advisory board on dentin hypersensitivity ( 2003 ) defined Dentin hypersensitivity (Tooth sensitivity) as “a short, sharp pain arising from exposed dentin in response to stimuli typically thermal, evaporative, tactile, osmotic or chemical and which cannot be ascribed to any other form of dental defect or disease.”  It has been described as the “common cold of dentistry” by some and
“toothbrush disease” by others when it occurs in the presence of gingival recession (Pashley et al. 2008 ).

Prevalence and Distribution
The condition is mostly prevalent among the young population in the 3rd and 4th decades. The prevalence may shift in the future to a younger age group because of the increase in acidic food/drink intake and the influence of greater oral hygiene awareness and measures (Chabanski et al. 1997; Clayton et al. 2002 ). Various intraoral locations can be affected with Dentin hypersensitivity. Sites of predilection in descending order are canines and first premolars, incisors and second premolars, and molars (Dababneh et al. 1999 ). The buccal surfaces are mostly affected, followed by labial, occlusal, distal, and lingual. Incisal and palatal surfaces are the least affected (Splieth and Tachou 2012; Amarasena et al. 2011 ).

Mechanism
Brännström’s ( 1962, 1992 ) hydrodynamic theory of dentin sensitivity proposed that hydrodynamic
stimuli (hot or cold, tactile, evaporative or osmotic) caused sudden minute shifts of dentinal fluid that activate pulpal mechanoreceptors to cause sharp, well-localized tooth pain, thought to be due to A-delta sensory nerves (Narhi et al., 1992 ).

Causes and Predisposing Factors
The most important factor to be present for tooth sensitivity is the loss of tooth structure and the exposure of dentin to the oral cavity. The dentin may be exposed to the oral cavity by either the loss of enamel or cementum and overlying periodontal attachment apparatus or loss of both at the same time. Following the exposure, the patent dentinal tubules remain wide open and thus are predisposed to any stimulus, called the phase of “lesion initiation.” However, not all exposed dentin is sensitive (Rimondini et al. 1995 ).

The loss of enamel may be either due to attrition, erosion, abrasion, abfraction or abrasion due to tooth brushing (most commonly cervical abrasion). Similarly, loss of cementum due to various causes and periodontal attachment loss may cause exposure of dentinal tubules. Some medical conditions like Bulimia Nervosa, Gastroesophageal reflux disease, Chronic alcoholism, Salivary hypofunction, etc. may also cause dentin hypersensitivity.

Diagnosis
Diagnosis of dentin hypersensitivity can be made by applying any of the mechanical, chemical, thermal or electrical stimuli. Electronic pulp testers (EPT), mechanical pressure stimulators, air jet stimulator, ethyl chloride, thermoelectric device, cold water testing, ice testing, etc. can be used for challenging the affected tooth.

Treatment 
Two treatment approaches are mainly practiced in the treatment of dentin hypersensitivity. They are:

•  Use of dentin blocking agents that occlude patent (open) tubules (fluoride, strontium salts, oxalate, calcium phosphate, restorative materials, etc.), and
• Nerve desensitization agents that reduce intradental nerve excitability (e.g. potassium ions, guanethidine) in order to prevent a response from intra dental nerves to the stimulus- evoked fluid movements within the dentin tubules

 Application of these successfully tested products may either involve ‘in-office’ procedures by a clinician using a restorative approach (for example, restorative materials in the form of dentin bonding agents, glass ionomer cements (GIC), and periodontal surgical techniques) or by a clinician recommending an over-the-counter (OTC) approach (involving toothpastes, gels, mouthwashes).

Furthermore, the causative agent has to be identified and avoided as much as possible and the patient should be educated about the proper brushing technique to prevent mechanical abrasion due to toothbrushing in the future.

By : Raman Dhungel, 

B.P. Koirala Institute of Health Sciences, Dharan, Nepal

References:

1. Canadian Advisory Board on Dentin Hypersensitivity (2003) Consensus-based recommendations for the diagnosis and management of dentin hypersensitivity. J Can Dent Assoc 69(4):221–226

2. Pashley DH, Tay FR, Haywood VB, Collins MA, Drisko CL (2008) Consensus-based recommendations for the diagnosis and management of dentin hypersensitivity. Inside Dentistry 4(9 (Special Issue)):1–35

3. Chabanski MB, Gillam DG, Bulman JS, Newman HN (1997) Clinical evaluation of cervical dentine sensitivity in a population of patients referred to a specialist periodontology department: a pilot study. J Oral Rehabil 24(9):666–672

4. Clayton DR, McCarthy D, Gillam DG (2002) A study of the prevalence and distribution of dentine sensitivity in a population of 17-58-year-old serving personnel on an RAF base in the Midlands. J Oral Rehabil 29(1):14–23, 805 [pii]

5. Dababneh RH, Khouri AT, Addy M (1999) Dentine hypersensitivity – an enigma? A review of terminology, mechanisms, aetiology and management. Br Dent J 187(11):606–611; discussion 603. doi: 10.1038/sj.bdj.4800345a , 4800345a [pii]

6. Brännström M (1992) Etiology of dentin hypersensitivity. Proc Finn Dent Soc 88(Suppl 1):7–13

7. Brännström M (1962) The elicitation of pain in human dentine and pulp by chemical stimuli. Arch Oral Biol 7:59–62

8. Närhi M, Jyvasjarv E, Vitanen A, Huopaniemi T, Ngassapa D, Hirvonen T (1992) Role of intra dental A and C type nerve fibers in dental pain mechanisms. Proc Finn Dent Soc 8(Suppl 1):507–516

9. Dababneh RH, Khouri AT, Addy M (1999) Dentine hypersensitivity – an enigma? A review of terminology, mechanisms, aetiology and management. Br Dent J 187(11):606–611. doi: 10.1038/sj.bdj.4800345a ; discussion 603

10. Clinician’s Guide to the Diagnosis and Management of Tooth Sensitivity ; Sahar Taha, Brian H. Clarkson ISBN 978-3-642-45163-8 ISBN 978-3-642-45164-5 (eBook) DOI 10.1007/978-3-642-45164-5

11. Rimondini L, Baroni C, Carrassi A (1995) Ultrastructure of hypersensitive and non-sensitive dentine. A study on replica models. J Clin Periodontol 22(12):899–902

12. Ling TYY, Gillam DG (1996) The effectiveness of desensitizing agents for the treatment of cervical dentine sensitivity (CDS) – a review. Periodontal Abstr 44(1):5–12

13. Orchardson R, Gillam D (2006) Managing dentin hypersensitivity. J Am Dent Assoc 137(7):990–998

Download these Textbooks of Dentistry as soon as possible

These are the important textbooks in Dentistry.

Oral Anatomy and Histology
1. Wheeler's Dental Anatomy, Physiology, and Occlusion    - Stanley J. Nelson
2. Woelfel's Dental Anatomy   - Rickne C. Scheid, Gabriella Weiss
3. Ten Cate's Oral Histology: Development, Structure, and Function    - Antonio Nanci
4. Orban's Oral Histology and Embryology  - G.S. Kumar
5. Oral Anatomy, Histology, and Embryology  - B.K.B. Berkovitz, G.R. Holland & B.J. Moxham

Oral Medicine and Radiology
1. Burket's Oral Medicine  - Michael Glick
2. Oral Radiology: Principles and Interpretation  - Stuart C. White, Michael J. Pharaoh

Oral and Maxillofacial Surgery
1. Peterson's Principles of Oral and Maxillofacial Surgery
2. An Introduction to Oral and Maxillofacial Surgery  - David A. Mitchell
3. Handbook of Local Anesthesia   - Stanley F. Malamed

Pediatric Dentistry / Pedodontics
1. Dentistry for the Child and Adolescent     - Ralph E. McDonald, David R. Avery
2. Principles and Practice of Pedodontics      - Arathi Rao

Orthodontics
1. Contemporary Orthodontics   - William R. Proffit
2. Orthodontics The art and Science - S.I. Bhalajhi
3. Orthodontics - Current Principles and Techniques - Graber, Vanarsdall ang Vig

Public  Health Dentistry
1. Jong's Community Dental Health   - George M. Gluck & Warren M. Morganstein
2. Dentistry, Dental Practice, and the Community  - Brian A. Burt, Stephen A. Eklund
3. Park's Textbook of Preventive and Social Medicine  - K. Park

Prosthodontics
1. Prosthodontic Treatment for Edentulous Patients     -    Zarb, Hobkirk, Eckert and Jacob
2. McCracken' Removable Partial Prosthodontics    - Alan B. Carr & David T. Brown


Periodontology
1. Carranza's Clinical Periodontology  - Newman, Takei, Klokkevold & Carranza
2. Clinical Periodontology and Implant Dentistry   - Niklaus P. Lang & Jan Lindhe

Operative Dentistry
1. Sturdevant's Art and Science of Operative Dentistry  - Harald O. Heymann, Edward J. Swift & André V. Ritter
2. Pickard's Manual of Operative Dentistry  - Avijit Banerjee & Timothy H. Watson

Oral Pathology
1. Shafer's Textbook of Oral Pathology  -  R. Rajendran & B. Sivapathasundharam
2. Oral and maxillofacial Pathology  - Neville, Damm, Allen, and Bouquot
3. Oral Pathology : Clinical pathologic Correlation  - Regezi, Sciubba & Jordan

BPKIHS Past Question : Endocrinology and Reproductive System - 2nd year MBBS

B.P. Koirala Institute of Health Sciences, Dharan

2^nd Year MBBS

Unit - 4

Internal Assessment, January 2000

Paper - IIA

(Endocrines & Reproduction)

Time: 2 hour                                                                                                                                Maximum Marks: 125

Short Answer Questions

Please answer each section in a separate answer book.

                                             Section 'A'

Anatomy

1.                Draw a neatly labeled histological diagram of a mature ovarian follicle (Grafian follicle).

Explain how theca externa is formed.                                                                                    3+1

2.            Define deep perineal pouch. Enlist six components of the deep perineal pouch.               2+3

3.            Explain in brief why incisions into the breast are usually made radially ?                             3

4.            Explain in brief the embryological basis of  thyroglossal cyst.                                              3

Acrylic Teeth Vs Porcelain Teeth

Property	Acrylic Teeth	Porcelain Teeth
Abrasion Resistance	Low	High
Adjustability	Easy	Difficult
Bonding	Chemical	Mechanical
Staining	Easily stained	Does not stain
Percolation	Absent when acrylic denture base is used	Present when acrylic denture base is used
Clicking Sound	Absent	Present
Ease of Fabrication	Easy	Difficult
Ease of rebasing	Difficult to remove acrylic teeth	Esay to remove porcelain teeth
Trauma to dental bearing area	Less	More