sravani

Amalgam Important Notes

1. Types Of Corrosion

2. Creep Values

3. Mercury Toxicity

• The maximum level of occupational exposure considered safe is 50 pg of mercury/m3 of air
• Mercury vapors may be released from the Ag-Hg phase which is melted during the polishing and amalgam removal process
• Rubber dam, high volume evacuation, and water cooling unit are used during the removal of amalgam
• Masks can’t filter mercury vapors
• Mercury toxicity results in acrodynia or Pink’s disease
• It is characterized by pinkish discoloration of the skin, profuse salivation, ulceration of the mucosa, and premature shedding of teeth
• Mercury has an average half-life of 55 days for transport through the body to the point of excretion
• Spent capsules and mercury-contaminated cotton rolls or napkins should be stored in tightly capped pressure containers

4. Forms Of Mercury

• Elemental mercury – vapor is inhaled and absorbed through the lungs at 80% efficiency
• Inorganic mercury – exists mainly as sulfide and is absorbed easily by GIT

Read And Learn More: Operative Dentistry Short And Long Essay Question And Answers

• Organic mercury in the form of methylmercury mercury – mainly carried through food

5. Failures Of Amalgam Restorations

• Bulk fractures of restorations
• Corrosion
• Excessive marginal fractures
• Sensitivity or pain
• Secondary caries
• Fracture of tooth structure

Amalgam Question and Answers

Question 1. Classify silver alloys. Give the role of each ingredient of silver alloy. Add a note on zinc alloys
(or)
Classify amalgam alloys, write the role of each ingredient, and add a note on gamma 2 phase

Answer:

Amalgam:

Dental amalgam is an alloy of mercury, silver, copper, and tin which may also contain palladium, zinc, and other elements to improve handling characteristics and clinical performance

Amalgam Classification:

1. Based On Copper Content

• Low copper alloys- contain less than 6% copper
• High copper alloys- contain between 13-30% cop-per

2. Based On Zinc Content

• Zinc containing alloys
• Zinc free alloys

3. Based On The Shape Of AThe Alloy Particle

• Lathe cut alloys
• Spherical alloys

4. Based On The Number Of Alloyed Metals

• Binary alloys
• Tertiary alloys
• Quaternary alloys

5. Based On The Size Of The Alloy

• Microcut
• Macrocut

Amalgam Composition:

Mercury:

• Mercury is added to the alloy

Platinum:

• Hardens the alloy
• Increases resistance to corrosion

Palladium:

• Hardens and whitens the alloy

Indium:

• Reduces mercury vapor and improves wetting

Zinc Free Alloys:

• Contains less than 0.01% zinc
• It avoids the delayed expansion of the amalgam which occurs in zinc-containing alloys
• This results in the prevention of dimensional change in the restoration
• Prevents micro-leakage and secondary caries formation

Gamma 2 Phase:

• Gamma 2 phase is Sn and Hg (Sn8Hg)
• Weakest component
• Hardness is 10% that of Gammal
• Least stable in a corrosive environment;

Question 2. Discuss in detail the manipulation of silver amalgam. Add a note on high copper amalgam.

Answer:

Manipulation Of Amalgam

1. Selection Of Materials:

• Alloy Selection:
  • For restorative purposes- high resistance amalgam is selected
  • For strength- High copper alloys are selected
  • If moisture control is difficult- non-zinc-containing alloys are selected
• Mercuryattoy Ratio:
  • To achieve smooth and plastic amalgam an amount of mercury in excess is desirable
  • But because of the harmful effects of excess mercury, it is necessary to reduce the amount of mercury
  • One of the methods for it is to reduce the original mercury/alloy ratio
  • This is called the Eames technique
  • Sufficient mercury must be present in the mix and it should be as low enough so that mercury content is acceptable during condensation
  • Ratio is 1:1

2. Trituration:

• Objective:
  • To wet all the surfaces of the alloy particles with mercury
  • The film should be rubbed off to obtain a clean surface of alloy for mercury
• Manual Mixing:
  • A glass mortar with a roughened inner surface and a pestle with a round end is used for mixing
  • It depends on
    • Number of rotations
    • Speed of rotations
    • Pressure placed on pestle
    • Mechanical mixing

Alloy and mercury are dispensed into the capsule
↓
The capsule is secured in the machine
↓
The machine is turned on
↓
The automatic timer is set
↓
Trituration is accompalished

3. Mulling:

• Mulling is continuation of trituration
• Mulling causes the mix to cohere so that it can be readily removed from the capsule
• Achieved by vigorously rubbing between first finger and thumb for 2-5 sec

4. Condensation:

• Amalgam is placed in a prepared cavity and condensed using suitable condensers
• Aims
  • To compact alloy into a prepared cavity
  • To remove any excess mercury in each increment
  • Reduces voids

5. Carving And Finishing:

• Carved to reproduce proper tooth anatomy
• Smoothen through burnishing with a ball bur¬nisher
• Final smoothening can be achieved by rubbing with a moist cotton pellet
• Polishing minimizes corrosion and prevents adherence to plaque
• It is delayed for 24 hours
• Wet polishing is desirable

High Copper Alloys:

• Contains 13-30%, weight copper
• They are preferred because of
  • Improved properties
  • Resistance to corrosion
  • Better marginal integrity
  • Improved performance in clinical trials

High Copper Alloys Types:

1. Admixed Alloys

• Regular type
• Unicomposition alloy

2. Single-Composition Alloy

Composition

High Copper Alloys Setting Reaction:

1. Admixed Alloy:

Components are mixed
↓
Mercury begins to dissolve the outer portion
of the particle
↓
Silver enters mercury and forms the yx phase
↓
Tin dissolved in mercury reacts with copper
and forms Cu₆ Sn₈

2. Single Composition:

Each particle contains Ag3 Sn, AgSn, and Cu3 Sn
↓
Silver and tin dissolve in mercury form the Yj phase
↓
Later a layer of Cu6 Sn8 is formed at the surface of the alloy
particles

High Copper Alloys Advantages:

• Sets fasts
• Low residual mercury
• Faster finishing
• High strength
• Low condensation pressure

High Copper Alloys Disadvantages:

• Less working time
• Condensation pressure is not sufficient

Question 3. Define class 2 cavity and enumerate various retention, resistance, and convenience forms in class 2 restoration.
(or)
Define retention form. discuss various methods of retention form in cavity preparation

Answer:

Class 2 Cavity:

• Preparation involving the proximal surface of posterior teeth is termed class 2

Retention

1. Primary Retention Form:

• It is the shape or form of the conventional prepara¬tion that prevents displacement or removal of the restoration by tipping or lifting forces for non-bonded restorations
  • Primary Retention Form For Amalgam Restoration
    • Occlusal convergence is provided
  • Primary Retention Form For Composite Restoration
    • Composite restorations are retained by micro¬mechanical bond
    • Bonding is increased by bevel and flare in enamel
  • Primary Retention Form For Cast Metal Restoration
• Obtained by
  • Parallel vertical walls
  • The small angle of divergence
  • Occlusal dovetail

2. Secondary Retention Forms:

• Grooves And Coves
  • At axiofacial and axiolingual line angles
  • For cast restoration
• Slots
  • In occlusal box, buccoaxial, linguoaxial and gin-gival walls
  • For amalgam and cast restoration
• Locks
  • In the proximal/occlusal box
  • For amalgam
• Pins – For amalgam, composite, and cast restoration
• Skirts
  • On all four sides of the preparation
  • For cast restoration
  • Amalgampins – For amalgam restoration

Resistance Form:

• Resistance Form may be defined as the shape and placement of the preparation walls that best enable the remaining tooth structure and the restoration to withstand, without fracture, masticatory forces delivered principally along the long axis of the tooth

Resistance Form Features:

• Relatively horizontal floors
• Box-like shape
• Inclusion of weakened tooth structure
• Prevention of cusps and marginal ridges
• Rounded internal line angles
• The adequate thickness of restorative material
• Reduction of cusps for capping, when indicated

Resistance Form Convenience Form:

• Convenience Form is the shape or form of the preparation that provides for adequate observation, accessibility, and ease of op¬eration in preparing and restoring the tooth
• Convenience Form is obtained by
  • Occlusal divergence of vertical walls
  • Extending proximal preparation beyond proximal contacts.

Question 4. Discuss tooth preparation of maxillary first mo¬lar for class 2 mesioocclusal amalgam restoration.

Answer:

Tooth preparation of maxillary first mo¬lar for class 2 mesioocclusal amalgam restora¬tion:

Steps

1. Outline Form:

• It means placing the preparation margins in the positions they will occupy in the final preparation except for finishing enamel walls and margins
• Using high-speed bur with air-water spray enter the pit on the occlusal surface area to the mesial surface
• Maintain an initial depth of 1.5-2 mm
• Extend upto central fissure
• Maintain uniformity of pulpal floor
• Enameloplasty is done if required
• Maintain width of the cavity to l/4th of the intercuspal distance
• Occlusal convergence is made
• Widen preparation faciolingually
• Proximal cutting upto 0.5-0.6 mm depth
• Make cavosurface angle of 90°
• Ideal clearance 0.3-0.5mm
• Preservation of marginal ridge
• The reverse curve in the case of broader contacts

2. Primary Resistance Rorm:

• Primary Resistance Rorm may be defined as the shape and placement of the preparation walls that best enable the remaining tooth structure and the restoration to with¬stand, without fracture, masticatory forces delivered principally along the long axis of the tooth

Primary Resistance Form Features:

• Box-shaped preparation
• Flat pulpal floor
• Inclusion of all weakened structure
• Cavosurface angle of 90o
• Rounded internal line and point angles
• Cusp. Capping
• Minimal width of preparation

3, Primary Retention Form:

• Primary Retention Form is the shape or form of the conventional preparation that prevents displacement or removal of the restoration by tipping or lifting forces for non-bonded restorations
• It is achieved by
  • Occlusal convergence
  • Dovetail

4. Convenience Form:

• Convenience Form is the form and shape of the cavity that enables ease of accessibility, visibility, and ease of operation.

5. Final Tooth Preparation:

• Inspect the preparation
• Removal of debris, old restorative material
• Removal of soft caries with a spoon excavator

6. Secondary Retention And Resistance Form:

• Retention grooves and locks in the proximal box
• Slots in the gingival floor

7. Pulp Protection:

• Use of pulp protective materials.

8. Finishing Of External Walls:

• Removal of all unsupported enamel
• Bevelling of the enamel of the gingival wall with GMT

Question 5. Principles of cavity preparation and describe secondary retention form in class 2 for amalgam restoration.

Answer:

Principles Of Cavity Preparation:

1. Cavity Preparation Initial Steps:

1. Cavity Preparation Outline Form:

• Placing the preparation margins to the place they will occupy in the final tooth preparation

Cavity Preparation Factors:

• Extension of all carious lesions
• Caries index
• Old restorative material
• Initial depth 0.2-0.8 mm
• Esthetics

Cavity Preparation Features:

• Preserve cuspal strength
• Preserve marginal ridge
• Minimize extension
• Maintain initial depth to 0.2-0.8 mm
• Enameloplasty wherever required

2. Primary Resistance Form:

• “Primary Resistance Form is that shape and form of the cavity which enables both tooth and restoration to withstand without fracture the stresses of masticatory forces delivered principally along the long axis of the tooth”

Primary Resistance Form Features:

• Box-shaped preparation
• Flat pulpal floor
• The adequate thickness of restorative material
• Preservation of marginal ridge
• Inclusion of weakened tooth structure
• Rounded internal line angles
• Cusp capping

3. Primary Retention Form:

• Primary Resistance Form is the form and shape of the cavity that resists the displacement of restoration from lifting and tipping forces

Primary Resistance Form Features:

• Occlusal convergence
• Dovetail

4. Convenience Form:

• Convenience Form is the form and shape of the cavity that enables ease of accessibility, visibility, and ease of operation

Convenience Form Features:

• Adequate extension
• Cavosurface margin
• Proximal clearance

Question 6. Discuss the causes of failure of amalgam restoration and how you manage them clinically.

Answer:

1. Poor Case Selection:

• Teeth with extensive caries
• Presence of para-functional habits
• Heavy masticatory form

amalgam Management:

• Proper case selection should be done
• Patient’s esthetic concerns, economic status, medical condition, and age should be taken into consideration
• Patients at high risk for dental caries may require an initial treatment plan to limit disease progression until caries risk factors are reduced or eliminated

2. Defective tooth preparation:

• Inadequate Occlusal Extension
  • Increased risk of secondary caries
• Under The Extension Of The Proximal Box
  • Not upto embrasure
  • Interferes with self-cleaning action
• Over-Extended Tooth Preparation
  • Tooth fracture
  • Need of cusp, capping
• Depth Of Preparation
  • Shallow cavity – Inadequate thickness of restorative material
  • Deep cavity – Pulpal damage

Defective tooth Management:

• Minimal occlusal thickness for resistance to fracture should be 1.5 mm
• Restrict the buccolingual extension of the external walls to allow strong cusp and ridge areas to remain with sufficient dentin support
• In case of extensive tooth preparation, cusp cap-ping is done
• A pulpal depth of approximately 1.5-2 mm and usually a maximum depth into the dentin of 0.2 mm is maintained

3. Defective Amalgam Manipulation:

• Incorrect Mercury Alloy Ratio
  • More the mercury, the less the strength
• Trituration
  • Overtriturated – shiny wet and soft
  • Under triturated – dry mix
• Improper Condensation
• Faulty Finishing And Polishing
  • Excessive heat production during polishing causes pulpal trauma
  • Heavy pressure during polishing -overhangs

Defective Amalgam Manipulation Management:

• Use proper mercury: alloy ratio as 1:1
• Use of proper triturated amalgam
• Amalgam should be adapted to all the walls
• Condensation done in small increments
• Use of coolant along with finishing and polishing of restoration

4. Defective Matrix Adaptation:

Defective Matrix Adaptation Management:

• The matrix should be properly contoured
• Use of wedge
• Stabilization of wedge
• Avoid premature removal of matrix band to prevent fracture of restoration

5. Defective Matrix Adaptation Post-Operative Failures:

• Postoperative pain – due to
  • High points
  • Zinc containing alloys
  • Dissimilar restoration
  • Thermal changes

Defective Matrix Adaptation Management:

• Use of zinc-free alloys to prevent delayed expansion
• Occlusal correction to reduce high points
• Avoid the use of dissimilar restoration to prevent galvanism

Amalgam Short Question and Answers

Question 1. Control of pain during cavity preparation.

Answer:

• The administration of local anesthesia to all tissues in the operating site is recommended in certain patients to eliminate pain and reduce salivation associated with tooth preparation and restoration

Factors Affecting Cavity Preparation

1. Patient Factors:

• Cardiovascular System
  • Before administration of a drug, the condition of the cardiovascular system must be assessed
• Central Nervous And Respiratory Systems
  • The central nervous system is affected by an overdose of injected anesthetic drugs
• Allergy
  • Allergy is an absolute contraindication for administration of local anesthetic

Cavity Preparation Advantages:

• Patient cooperation
• Salivation control
• Hemostasis
• Operator efficiency

Cavity Preparation Technique:

• Before needle entry, the mucosa at the injection site should be wiped free of debris and saliva with sterile gauze
• After this, a lidocaine topical anesthetic ointment is applied for a minimum of 1-2 minutes to the selected entry site
• Lidocaine 2% with 1:100,000 epinephrine is commonly used in operative dentistry
• 1 ml provides infiltration anesthesia for 40-60 minutes for anterior teeth
• Painless injection is achieved by a combination of the following
  • Use of topical anesthetic
  • Use of sharp needle
  • Slow deposition rate

Question 2. Mercuroscopic expansion.

Answer:

Mercuroscopic Expansion:

• Mercuroscopic expansion is proposed by Jorgensen
• It occurs due to electrochemical corrosion
• During this corrosion mercury from tin-mercury reacts with silver-tin particles and produces expansion
• Corrosion is due to the oxidation of the tin-mercury phase of amalgam leading to the formation of oxides and oxychlorides in tin
• The oxide precipitates as crystals and tends to fill up the spaces occupied by the original tin-mercury phase
• It can occur anywhere on or within a set amalgam
• This leads to extrusion at margins which has a greater prevalence of marginal fracture associated with occlusal amalgam
• Such expansion is known as macroscopic expansion

Question 3. Burnishing.

Answer:

Burnishing:

• Done after condensation
• To make the surface shiny
• Amalgam is overfilled and burnished immediately

Burnishing Types:

1. Pre-Carve Burnishing

• Reduce mercuric content
• Creates gross anatomy
• Done with a large burnisher

2. Post-Carve Burnishing

• Done after completion of the carving
• Done with a small-size burnisher
• To remove traces of carving

Question 4. Trituration and condensation of Amalgam.

Answer:

Trituration And Condensation Of Amalgam:

Trituration:

Trituration is the process of removal of the oxide layer from the alloy particles to coat each particle with mercury, resulting in a homogenous mass

Trituration Method:

1. Manual
2. Mechanical

Trituration Objectives:

• Result in workable mass
• Removal of the oxide layer
• Dissolution of alloy into mercury
• Reduces y1 and y2

Trituration Types:

• Normal – Homogenous mass
• Overtriturated – warm, shiny wet, and soft
• Under triturated – Dry, weak

Trituration Condensation:

• Types Of Condensers
  • Triangular
  • Round
  • Elliptical
  • Trapezoidal
  • Rectangular
• Rules:
  • Done in increments
  • Condense laterally and apically
  • Have a constant supply of amalgam
  • Apply adequate force
  • Depends on the type of alloy
    • Lathe cut alloy – Small condenser
    • Blended alloy-Small condenser
    • Spherical alloy-Large condenser

Question 5. Various cavity designs for Class 2.

Answer:

Various Cavity Designs For Class 2:

Question 6. Tarnish and Corrosion.

Answer:

Tarnish And Corrosion:

Question 7. Finishing and Polishing of Amalgam.

Answer:

Finishing And Polishing Of Amalgam:

• Involves the removal of marginal irregularities, obtaining proper contours, and smoothening the restoration
• Polishing creates a smooth, shiny luster on the surface of the amalgam

Finishing And Polishing Of Amalgam Time:

• After 24 hours of restoration
• Premature – Interferes with a crystalline structure

Finishing And Polishing Of Amalgam Advantages:

• Marginal adaptation
• Reduce tarnish and corrosion
• Plaque resistance
• Prevent recurrent caries
• Prevent occlusal problems
• Maintain periodontal health

Finishing And Polishing Of Amalgam Steps:

• Evaluate marginal integrity by explorer
• Evaluate occlusal pattern
• Smoother margins by round bur
• Eliminate scratches by large round finishing bur
• Smoothen occlusal surface by side of burs
• Smoothen margins by finishing the strip
• Smoothen facial and lingual surfaces with a finishing disk
• Rinse and clean out debris
• Evaluate all margins and surfaces

Question 8. Mercury Hygiene.

Answer:

Mercury Hygiene:

• Follow aseptic technique
• Knowledge about mercury disposal and storage
• Use of proper ventilation
• Checking mercury levels periodically
• Avoid carpet/floor covering
• Storage of mercury in a closed container in an isolated area
• Use of pre-capsulated alloy
• Use of amalgamator
• Polishing, along with coolant
• Avoid direct contact with skin
• Use of evacuators
• Disposal in a closed plastic container
• Clean spilled mercury
• Remove protective clothing before leaving the operating area

Question 9. Differences between amalgam and inlay cavity

Answer:

Differences BBetween Amalgam And Inlay Cavity

Question 10. Resistance form in cavity preparation

Answer:

Resistance Form In Cavity Preparation:

It may be defined as the shape and placement of the preparation walls that best enable the remaining tooth structure and the restoration to withstand, without fracture, masticatory forces delivered principally along the long axis of the tooth

Resistance Form In Cavity Preparation Features:

• Relatively horizontal floors
• Box-like shape
• Inclusion of weakened tooth structure
• Prevention of cusps and marginal ridges
• Rounded internal line angles
• The adequate thickness of restorative material
• Reduction of cusps for capping, when indicated

Amalgam Short Answers

Question 1. High copper alloy.

Answer:

High Copper Alloy:

• Contains more than 6% copper

High Copper Alloy Types:

• Admixed
• Single composition

High Copper Alloy Advantages:

• Elimination of weakest 72-phase
• Improved mechanical properties
• Corrosion resistance
• Better marginal integrity

Question 2. Reverse Curve.

Answer:

Reverse Curve:

• Used in proximal preparation for class II amalgam restoration
• Indicated for broader contacts

Reverse Curve Features:

• Curving proximal walls inwards towards the contact area

Reverse Curve Importance:

• Useful as if excessive flare is given it results in weakening of tooth structure and fracture of restoration

Reverse Curve Advantages:

• Conserves tooth structure
• Preserves marginal ridge
• Increases resistance for tooth and restoration

Question 3. Convenience form.

Answer:

Convenience Form:

Convenience Form is the form and shape of the cavity that enables ease of accessibility, visibility, and ease of operation

Convenience Form Features:

• Adequate extension
• Cavosurface margin
• Proximal clearance

Question 4. Retention locks.

Answer:

Retention locks:

• Retention locks is a secondary retentive form for class 2 cavity preparation
• Used for amalgam restoration
• Placed in the proximal or occlusal box
• Prepared where sufficient vertical tooth preparation permits

Question 5. Cavosurface angle /Butt joint.

Answer:

Cavosurface Angle:

• The Cavosurface Angle is an angle formed between the preparation wall and the external tooth surface

Cavosurface Angle Factors Effecting:

• Location of tooth
• Type of restorative material
• The direction of enamel rods

Cavosurface Angle Value:

• 90° for amalgam
• 110o-120o for cast

Cavosurface Angle Significance:

• If increased results in restoration fracture
• If decreased results in tooth fracture

Question 6. Delayed expansion.

Answer:

Delayed Expansion:

• If zinc-containing amalgam is contaminated by moisture during trituration or condensation a large expansion can take place
• Delayed expansion usually starts after 3-5 days and continues upto months reaching 400 pm
• This is called “delayed expansion”
• H₂O + Zn → ZnO + H₂ [gas]
• Effects of Liberated H₂ Gas

Produce internal stresses
↓
Expansion of mass
↓
Increased creep
Increased microleakage
Pitted surface and corrosion
↓
Dental pain
Recurrence of caries
Fracture of restoration

Question 7. Axio-pulpal line angle.

Answer:

Axio-Pulpal Line Angle:

Line Angle:

• Junction of two surfaces

Axio-Pulpal Line Angle:

• The junction between the axial wall and pulpal floor

Axio-Pulpal Line Angle Significance:

• In amalgam restoration, there needs to be a curved axio-pulpal line angle
• Straight axio-pulpal line angle results in increased stress concentration over it leading to fracture

Question 8. Enameloplasty.

Answer:

Enameloplasty:

• Enameloplasty is the cauterization of the enamel surface

Enameloplasty Reason:

• In the case of a deep pit and fissure, the bristles of the toothbrush are unable to reach those areas
• By cauterization/enameloplasty these areas are converted to self-cleansable areas

Enameloplasty Features:

• Fissure present <l/3rd of enamel thickness
• Covering only a superficial portion of the enamel

Question 9. Bonded Amalgam restoration.

Answer:

Bonded Amalgam Restoration:

Bonded Amalgam Restoration Mechanism:

Resin liner mixes with amalgam
↓
Forms micromechanical union
↓
Increases retention
↓
The liner acts between hydrophobic amalgam and hydro–Philip’sp tooth

Bonded Amalgam Restoration Indications:

• Weak preparation
• Extensive caries
• Deep bite
• Core foundation

Bonded Amalgam Restoration Advantages:

• Dentin sealing
• Increased resistance
• Increased retention
• Conserve tooth structure
• Improved marginal seal
• Cost-effective

Question 10. Mulling.

Answer:

Mulling:

• Continuation of trituration
• Coat all alloy particles with mercury

Mulling Methods:

• Manually squeezing amalgam in chamois skin
• Mechanical – By increased trituration for 1-2 sec.

Question 11. Amalgampins.

Answer:

Amalgampins:

• Vertical posts of amalgam in dentin

Amalgampins Dimensions:

• Depth on the gingival floor – 1-2 mm
• Width – 0.5 -1 mm

Amalgampins Advantages: Increases resistance and retention

Question 12. Disposal of scrap amalgam.

Answer:

Disposal Of Scrap Amalgam:

• Store all scrap amalgam in a tightly closed container either dry or under a radiographic fixer solution
• Amalgam scrap should not be stored in water
• If the scrap is stored dry, mercury vapor can escape into room air when the container is opened
• If the scrap is stored under a radiographic fixer solution, special disposal of the fixer may be necessary
• Dispose of mercury-contaminated items in sealed bags according to applicable regulations
• Do not dispose of mercury-contaminated items in regulated waste containers or bags or along with waste that will be incinerated
• Clean up spilled mercury properly using trap bottles, tape, or freshly mixed amalgam to pick up droplets and commercial cleanup kits
• Do not use a household cleaner

Question 13. Mercury hygiene

Answer:

Mercury Hygiene:

• Follow aseptic technique
• Knowledge about mercury disposal and storage
• Use of proper ventilation
• Checking mercury levels periodically
• Avoid carpet/floor covering
• Storage of mercury in a closed container in isolated areas of pre-capsulated alloy
• Use of amalgamator
• Polishing, along with coolant
• Avoid direct contact with skin
• Use of evacuators
• Disposal in a closed plastic container
• Clean spilled mercury
• Remove protective clothing before leaving the operating area

Amalgam Viva Voce

1. Increasing copper content greater than 12% by weight in amalgam alloy suppresses the formation of more corrosive gamma-2 phase
2. High copper amalgamate is more corrosion-resistant than low copper amalgam
3. Mercury: alloy ratio in Eames technique is 1:1
4. Use of zinc-containing alloys results in delayed expansion
5. Tin-mercury gamma-2 phase is the weakest in dental amalgam
6. The threshold limit value for exposure to mercury va¬pour for a 40-hour work week is 50pg/m³

Fundamentals Of Cavity Preparation Important Notes

1. Angles In The Cavity

2. Walls In Cavity Preparation

3. Steps In Cavity Preparation

• Initial Cavity Preparation
  • Outline form
  • Primary Retention form
  • Secondary Resistance form
  • Convenience form
• Final Cavity Preparation
  • Removal of carious dentin
  • Pulp protection
  • Secondary retentive and resistance forms
  • Finishing of external walls
  • Cleaning, inspecting, and conditioning

4. Resistance Features

• Relatively flat floor
• Box shape

Read And Learn More: Operative Dentistry Short And Long Essay Question And Answers

• Preservation of cusps and marginal ridges
• Rounded internal and external line angles
• Cusp capping when indicated

5. Primary Retentive Forms

6. Secondary Retentive And Resistance Form

• Locks, pins, slots, steps and amalgam pins in amalgam provide secondary resistance and retentive forms
• Grooves, groove extensions, beveled enamel margins, and luting cement provide secondary retentive and resistance forms in cast metal restorations

7. Purpose Of Bevelling

• Produces stronger enamel wall
• Permits marginal seal in slightly undersized casting
• Provides marginal metal that is more easily burnished and adapted
• Assists in sealing gingival margins of castings that fail to seat by a very slight amount

Fundamentals Of Cavity Preparation Long Essays

Question 1. Enumerate steps in cavity preparation. Explain the outline form, retention form, and resistance form.

Answer:

Steps In Cavity Preparation:

• Initial cavity preparation
• Outline form
• Primary Retention form
• Secondary Resistance form
• Convenience form
• Final cavity preparation
• Removal of carious dentin
• Pulp protection
• Secondary retentive and resistance forms
• Finishing of external walls
• Cleaning, inspecting, and conditioning

Cavity Preparation Outline Form:

• Placing the preparation margins to the place they will occupy in the final tooth preparation

Cavity Preparation Factors:

• Extension of all carious lesions
• Caries index
• Old restorative material
• Initial depth 0.2-0.8 mm
• Aesthetics

Cavity Preparation Features:

• Preserve cuspal strength
• Preserve marginal ridge
• Minimize extension
• Maintain initial depth to 0.2-0.8 mm
• Enameloplasty wherever required

Retention Form

• Retention Form is the form and shape of the cavity that resists the displacement of restoration from lifting and tipping forces

Retention Form Features:

• Occlusal convergence
• Dovetail

Resistance Form

• “Resistance Form is that shape and form of the cavity which enables both tooth and restoration to withstand without fracture the stresses of masticatory forces delivered principally along the long axis of the tooth”

Resistance Form Features:

• Box-shaped preparation
• Flat pulpal floor
• The adequate thickness of restorative material
• Preservation of marginal ridge
• Inclusion of weakened tooth structure
• Rounded internal line angles
• Cusp capping

Fundamentals Of Cavity Preparation Short Essays

Question 1. G.V. Black’s classification of cavity preparation.

Answer:

G.V. Black’s Classification Of Cavity Preparation:

Fundamentals Of Cavity Preparation Short Answers

Question 1. Reverse bevel.

Answer:

Reverse Nevel:

• A reverse bevel is a bevel of generous width that is prepared on the facio margin of a reduced cusp with a flame-shaped, fine grit diamond instrument
• Its width should extend beyond any occlusal contact with opposing teeth
• Reverse Nevel should be at an angle that results in a 30-degree marginal metal
• The Reverse Nevel should be wide enough so that the cave surface margin is beyond any contact with the opposing dentition

Question 2. Reverse curve.

Answer:

Reverse Curve:

• Used in proximal preparation for class II amalgam restoration
• Indicated for broader contacts

Reverse Curve Features:

• Curving proximal walls inwards towards the contact area

Reverse Curve Importance:

• Useful as if excessive flare is given it results in weakening of tooth structure and fracture of restoration

Reverse Curve Advantages:

• Conserves tooth structure
• Preserves marginal ridge
• Increases resistance for tooth and restoration

Fundamentals Of Cavity Preparation Viva Voce

1. GV Black simply classified cavities as one class of pit and fissure and four classes of smooth surface caries
2. Cavities that occur exclusively in posterior teeth are class 2 cavities
3. Cavities that occur both in anterior and posterior teeth are class 1 and 6
4. A cavity preparation that includes both internal and external cavity walls is termed intracoronal preparation
5. Enameloplasty is indicated when the fissure depth is not more than 1 /3rd the thickness of the enamel
6. The class 5 cavity preparation is convex mesiodistally
7. Cavities of the cusp tips of posterior teeth are class 6 cavities
8. The axial wall is the base of class 3 preparation.

Pulp Protection Important Notes

1. Methods Of Pulp Protection

2. Effect Of Remaining Dentinal Thickness On Pulp

3. Classification Of Pulp Protective Agents

• Cavity Sealers
  • Varnishes
  • Resin bonding agents
• Cavity Liners
  • Calcium hydroxide
  • GIC
• Cavity Bases
  • Zinc phosphate
  • Zinc polycarboxylate
  • GIC

4. MTA (Mineral Trioxide Aggregate)

• It was developed by Torabinejad et al in 1993
• Used as a direct pulp capping agent
• Composed of tricalcium silicate, dicalcium silicate and traces of magnesium oxide, sodium sulphate and potas¬sium sulphate
• Bismuth oxide is added for radiopacity

Pulp Protection Short Essays

Question 1. Management of shallow and deep carious.

Answer:

Management Of Shallow And Deep Carious:

1. Shallow Caries:

Excavation of caries
↓
Application of liner over the axial and pulpal wall
↓
Placement of base
↓
Permanent restoration

2. Deep Caries:

Indirect Pulp Capping:

Direct Pulp Capping:

Read And Learn More: Operative Dentistry Short And Long Essay Question And Answers

Question 2. Methods of protecting the pulp.

Answer:

Methods Of Protecting The Pulp:

Depends on the use of restorative material and the depth of the cavity

Question 3. Zinc Phosphate.

Answer:

Zinc Phosphate:

High strength base

Zinc Phosphate Composition

• Powder 
  • Zinc oxide – 90.2%
  • Magnesium oxide – 8.2% Water – 36%
  • Other oxides – 0.2%
  • Silica – 1.4%
• Liquid
  • Phosphoric acid – 38.5%
  • Aluminium phosphate – 16.2%
  • Aluminium – 2.5%
  • Zinc – 7.1%

Zinc Phosphate Manipulation:

• Powder/liquid ratio – 1.4 g/0.5 ml
• Dispense on a cool dry glass slab
• Mix using a stainless steel cement spatula in a circular motion
• Mixing time: Each increment – 15-20 sec, total – 1 min.

Zinc Phosphate Uses:

• Luting cement, bases
• Intermediate restorations, root canal restorations

Question 4. Cement Bases.

Answer:

Cement Bases:

A layer of cement placed beneath permanent restoration

Cement Bases Types:

1. High strength – Thermal protection
2. Low strength – Chemical protection

Cement Bases Properties:

• Thermal fracture or distortion

Cement Bases Examples:

• Zinc phosphate
• GIC
• Calcium hydroxide

Pulp Protection Short Answers

Question 1. Varnish.
(or)
Give composition and objectives of varnishes.

Answer:

Varnish:

• Varnish is an organic copal or resin gum suspended in solutions of ether or chloroform

Varnish Composition

• Solid- Copal resin
• Solvent- Ether, acetone, alcohol

Varnish Action:

• On application, it evaporates leaving behind a protective Film

Varnish Advantages:

• Improves sealing ability of amalgam
• Reduces post-operative sensitivity
• Prevents discolouration of tooth

Varnish Indications:

• Pulpal protection
• Sealing of dentinal tubules
• Reduces microleakage
• Protects tooth from chemical irritants

Varnish Contraindications:

• Under composite resin
• UnderGIC

Question 3. Liners.

Answer:

Liners:

• Liners are fluid materials that adapt more readily to all aspects of a tooth
• Creates uniform, even surface
• Aids in the adaptation of materials such as amalgam
• Has poor strength so cannot be used alone

Liners Indications:

• Pulpal protection
• Formation of reparative dentin

Liners Materials Used:

• ZOE
• Calcium hydroxide
• Flowable composites
• GIC

Pulp Protection Viva Voce

1. GV Black simply classified cavities as one class of pit and fissure and four classes of smooth surface caries
2. Cavities that occur exclusively in posterior teeth are class 2 cavities
3. Cavities that occur both in anterior and posterior teeth are class 1 and 6
4. A cavity preparation which includes both internal and external cavity walls is termed intracoronal preparation
5. Enameloplasty is indicated when fissure depth is not more than l/3rd the thickness of enamel
6. The class 5 cavity preparation is convex mesiodistally
7. Cavities of the cusp tips of posterior teeth are class 6 cavities
8. The axial wall is the base of class 3 preparation.

Matricing Important Notes

1. Matrices

Matricing Short Essays

Question 1. Define matrix. Discuss different types of matrices
(or)
Define Matrix. Describe matrices used for class 2 restoration.
(or)
Matrices used in operative dentistry

Answer:

Matrix Definition:

Read And Learn More: Operative Dentistry Short And Long Essay Question And Answers

• Matrix is a device that is applied to a prepared tooth before the insertion of the restorative material to assist in the development of the appropriate axial tooth contours and to confine the restorative material excess

Types Of Matrices:

1. Based On The Mode Of Retention

• With retainer- Tofflemire matrix
• Without retainer- Automattrix

2. Based On The Type Of Band

• Metallic nontransparent matrices
• Non-metallic transparent matrices

3. Based On The Type Of Cavity

• Matrix For Class 1 Cavity
  • Double band tofflemeir
• Matrices For Class 2 Cavity Preparation
  • Single banded tofflemeir matrix
  • Rigid material supported sectional matrix
  • Ivory no. 8
  • Ivory no 6
  • Copper band matrix
• Matrices For Class 3 Cavities
  • Mylar strip matrix
  • S-shaped matrix
• Matrices For Class 4 Cavities
  • Custom lingual matrix
  • Mylar strip matrix
• Matrices For Class 5 Cavities
  • Window matrix
  • Cervical matrix

Matrices For Class 2 Restoration:

1. Ivory Matrix No. 1:

• For unilateral class 2

Ivory Matrix Parts:

• Claw
• Arms – 2 semicircle arms with pointed projections
• Tightening screw
• Band has a slightly projected part in the middle that is placed gingivally

Ivory Matrix Placement:

• Select and place the band
• Place the retainer
• Tighten the screw

2. Ivory Matrix No. 8:

• Band thin sheet of metal
• Circumference of it adjusted by screw

• Used in unilateral/bilateral cases

3. Tofflemire Universal Matrix Band Retainer:

• Used in all types of tooth preparations

Tofflemire Universal Matrix Band Retainer Parts:

• Head
• Slot
• Knurled nuts – Large and small

Tofflemire Universal Matrix Band Retainer Placement:

• Open large Knurled nut
• Open a small knurled nut in the opposite direction
• Secure both ends of the band
• Place the band into a diagonal slot
• Tighten small knurled nut
• Place the retainer around the tooth
• Tighten large knurled nut

4. Compound Supported Matrix:

• Place the band around the tooth
• Secure it by sealing with an impression compound

5. Auto-Matrix:

• Preformed bands are available
• Adapt the matrix around the tooth
• Tighten the band with a locking device

6. T-Shaped Matrix:

• Made of brass, copper, or stainless steel
• The long arm of T surrounds the tooth and overlaps the short arm

Question 2. Matrix Band and Retainer.

Answer:

Matrix Band And Retainer:

Matrix Band And Retainer Retainer:

• Holds the band in position and shape

Matrix Band And Retainer Band:

• A piece of metal/polymeric material used to give support and form to the restoration while insertion and setting

Matrix Band And Retainer Materials:

• Stainless steel
• Polyacetate
• Cellulose acetate
• Cellulose nitrate

Matrix Band And Retainer Dimensions:

• Width –¼ %” to 3/8″ for permanent
  • 1/8” to 5/16″ for deciduous
• Thickness – 0.0015″ to 0.002″

Matrix Band And Retainer Functions:

• Confines the restoration
• Provide good contour
• Provide surface texture
• Prevent overhanging

Matrix Band And Retainer Requirement:

• Rigid
• Adaptability
• Easy to use
• Easy to removal
• Non-irritant
• Sterilizable
• Inexpensive

Question 3. Non-metallic matrix.
(or)
Matrices for tooth-colored materials

Answer:

Non-Metallic Matrix:

• Used for tooth-colored restoration

Non-Metallic Matrix Types:

1. Celluloid strips – For silicate cement
2. Cellphone strips – For resins
3. Mylar strips – For composite and silicate

Non-Metallic Matrix Technique:

• Obtain the desired length of the matrix
• Burnish it over the tooth
• Placement of wedge
• Restoring the tooth
• Hold the matrix till the initial setting

Non-Metallic Matrix Indications:

• Class 3 and Class 4 restoration

Non-Metallic Matrix Advantage:

• Simple to Use
• Economic

Non-Metallic Matrix Disadvantage:

• Lack of stability

Matricing Short Answers

Question 1. Functions of the matrix.

Answer:

Functions Of The Matrix:

• Functions Of Matrix Are
• Rigidity
• Establishment of proper anatomic contour
• Restoration of correct proximal contact relation
• Prevention of gingival excess
• Convenient application
• Ease of removal

Question 2. Automatic.

Answer:

Automatic:

• Bands are performed and disposable
• Height of band-3/16″-5/16″
• The thickness of band – 0.038-0.05 mm

Automatic Steps:

Adapt matrix around the tooth
↓
Tighten the band with a locking device
↓
Restore the tooth
↓
Cut the band with a plier

Automatic Indications:

• Tilted and partially erupted teeth
• Complex amalgam restoration

Automatic Advantages:

• Simple
• Convenient
• Good visibility

Automatic Disadvantage:

• Expensive

Question 3. S-shaped matrix.

Answer:

S-Shaped Matrix:

S-Shaped Matrix Indications:

• Restoring the distal part of the canine and premolar
• Class 2 slot restoration

S-Shaped Matrix Advantages:

• Good contour

S-Shaped Matrix Disadvantage:

• Cumbersome

S-Shaped Matrix Technique:

• Twist the band in S shape
• Place interproximal over facial
• The surface of the tooth and the lingual surface of the bicuspid

Question 4. Copper Band.

Answer:

Copper Band:

Copper Band Application:

Select an appropriate copper band that surrounds the tooth
circumferentially 1-2 mm beyond the preparation margins
↓
Mount it over the softened stick of compound
↓
Fill it with restoration
↓
Place it over the tooth

Copper Band Indication – Class 5 preparation

Copper Band Advantage – Simple, Good contour

Question 5. Sectional matrix system.

Answer:

Sectional Matrix System

• It consists of dead soft metal matrices available in various shapes, thicknesses, and sizes
• They are selected according to the tooth to be restored

Sectional Matrix System Indications:

• For small to moderate class 2 cavities involving one or both proximal surfaces in posterior teeth
• For both amalgam and composite restorations

Sectional Matrix System Advantages:

• Easy to use
• Good visibility
• Contact dimensions are adequate
• Gingival adaptation of restoration is good

Sectional Matrix System Disadvantages:

• Expensive
• Matrix bands may become dented easily

Matricing Viva Voce

1. Matrix system consists of a matrix band, retainer, and wedges
2. The thickness of a matrix band is 0.002 inches
3. Matrix retainers are gadgets used to retain the matrix bands in position
4. Tofflemire matrix band retainer is ideal to use when MOD preparation is done
5. Automatrix is a retainer less matrix system with 4 types of bands used to fit all teeth
6. Ideally the matrix band should be positioned 1mm apical to the gingival margin and 1-2 mm above the adjacent marginal ridge
7. Tofflemire matrix is the universal matrix
8. Compound-supported matrix is also called custom- made matrix or anatomical matrix
9. T band matrix is performed T-shaped matrix without a retainer

Separation Important Notes

1. Types of separators

• Two Types
  • Slow Separation
    • The teeth are separated by inserting certain materials between them
  • Rapid Separation
    • Rapid separation is achieved by the wedge principle and traction principle

Read And Learn More: Operative Dentistry Question And Answers

2. Wedges

Separation Short Essays

Question 1. Separation of teeth / Tooth Separators / Indication of Separators.

Answer:

Separation of teeth / Tooth Separators / Indication of Separators:

Separation Of Teeth Definition:

Separation of teeth is the process of separating the involved teeth slightly away from each other or bringing them closer to each other and/or changing their spatial position in one/more dimension

Separation Of Teeth Purpose:

• Diagnosing the proximal caries
• Accessibility to proximal area
• Polishing of proximal restoration
• Matrix placement
• Removal of foreign bodies
• Repositioning shifted teeth

Separation Of Teeth Methods:

1. Slow/Delayed Separation:

• Rubber Ring/Band
  • Orthodontic purpose
  • Needs 2-3 days to 1 week
• Rubber Dam Sheet
  • Heavy/extra-heavy type used
  • Needs 1-24 hours/more
• Ligature Wire
  • Separation in 2-3 days
• Oversized temporary crowns
• Fixed orthodontic appliances

2. Rapid/Immediate Separation:

• Traction Principle:
  • Ferrier double bow
  • Has 2 bows, each bow engages the proximal tact area of the tooth

• • Use – Tooth preparation
  • Finishing and polishing
• Wedge Principle:
  • Elliot separator
  • Wedges

Question 2. Wedges and Wedging methods.

Answer:

Wedges:

• Devices for rapid tooth separation

Wedges Functions:

• Rapid tooth separation
• Prevent overhanging restoration
• Stabilizes matrix band
• Gingival retraction
• Adapt/contour restoration in cervical areas

Wedges Types:

1. Wooden Wedges:

• Easily trimmed
• Shapes:
  • Triangular
  • Round

2. Plastic Wedges:

• Light transmitting wedge
• Used for composite restoration
• Size: Length of wedge 1-1.2 cm

Wedging Techniques:

1. Double Wedging:

• Two wedges are used
• One inserted from the buccal embrasure
• Other from the lingual embrasure

2. Wedge Wedging:

• Two Wedges Are Used:
  • One inserted from the lingual embrasure
  • Another Inserted between the first wedge and matrix band
• Indication 
  • The mesial aspect of maxillary first premolar due to the presence of flutes

3. Piggyback Wedging:

• Two Wedges Are Used:
  • A larger one inserted from the lingual embrasure
  • Smaller one is placed over it
  • Use – Gingival recession

Separation Short Answers

Question 1. Elliot Separator.

Answer:

Elliot Separator:

• Synonym: Crab-claw separator

Elliot Separator Parts:

• Bow
• Two holding jaws
• Tightening screw

Elliot Separator Placement:

• Place the jaws gingival to the contact area
• Tighten the screw in a clockwise direction

Elliot Separator Precaution:

• Avoid tooth separation beyond the thickness of PDL i.e. 0. 2-0.5mm

Elliot Separator Uses:

• Diagnosis of proximal areas
• Polishing of proximal restoration

Separation Viva Voce

1. Wedges are third component of the matrix system
2. Wedges must be triangular or trapezoidal in cross-section
3. The gingival aspect of the wedge may be lightly moistened with lubricant to facilitate its placement
4. The tightness of the wedge is tested by pressing the tip of an explorer firmly at several points along the middle two-thirds of the gingival margins
5. A triangular wedge is used for preparations with mar-gins deep in the gingival sulcus
6. A round wedge is used for preparations with margins coronal to the gingival sulcus
7. The wedge is kept as short as possible

Sterilisation And Infection Control Important Notes

1. Critical Items

• Includes instruments that contact tissues or penetrate tissues
• Usually, there are disposable or single-use items
• Example: scalpels, blades, endodontic files, syringes, etc

2. Semi-Critical Items

• Items that are handled by gloved hands coated with blood and saliva or that may touch mucosa
• These can be either disposable or they can be cleared, sterilized or disinfected
• Example:  air water syringe tip, suction tips, prophy angle, handpiece

3. Noncritical Items

• These are environmental surfaces such as chairs, benches, floors, walls, and supporting equipment
• They are not ordinarily touched during treatment
• These surfaces can be cleaned, disinfected, and covered

Read And Learn More: Operative Dentistry Short And Long Essay Question And Answers

Sterilisation And Infection Control Long Essays

Question 1. Discuss various methods of sterilization.

Answer:

Various Methods Of Sterilization:

Sterilization:

Sterilization is defined as the process by which an article, surface, or medium is freed of all living organisms either in a vegetative/spore state. Its method is.

Sterilization Steps:

1. Presoaking:

• Prevent drying of blood, saliva, and debris
• Facilitate cleaning

2. Cleaning:

• Remove blood and saliva

Sterilization Types:

1. Manual – Use of nylon brushes + detergents
2. Ultrasonic – Provide fast and thorough cleaning
3. Enzyme cleaning – Has specific catalytic behavior

3. Packaging:

• Protects instruments from contamination after sterilization and before use

Sterilization Materials:

1. Self-sealing
2. Paper plastic
3. Peel pouches

• Sterilization
• Monitoring of sterilization
• Handling of processed instruments

Sterilization Of Different Instruments:

Question 2. Infection Control.

Answer:

Infection Control Methods:

Immunization: Vaccination recommended for Hepatitis B for all dental personnel

Personal Barrier

1 Handwashing:

2. Gloves:

• Protects against contamination
• Changed between patients and for the same patient if it is worn/torn

Infection Control Types:

1. Surgical
2. Latex
3. Vinyl
4. Double gloves for HBV and HIV [Hepatitis B Virus and Human Immunodeficiency Virus]

1. Face masks:

• Protects from inhalation of aerosols
• Prevents spatter from patient’s mouth
• Prevents splashes of contaminated solution
• Changed once per hour/between patients/whenever it becomes moist

2. Protective clothing:

• Reusable/disposable gowns with long sleeves, high neck, and long knee length

3. Eyewear:

• Prevention against Hepatitis B
• Prevent bacterial/viral contact

Infection Control Surgical Asepsis:

• Preparation of surgical site
• Draping the patient
• Isolation

Infection Control Surface Asepsis:

• Sterilization of instruments
• Use of disposable instruments
• Wrapping with aluminum foil or applying disinfectant to things that are often touched during treatment such as dental light, chair

Infection Control Disposable of waste:

• Methods:
  • Incineration
  • Burial in a landfill
  • Discharge of liquid to a sewer
  • Sterilization

Sterilization And Infection Control Short Essays

Question 1. Hot Air Oven.

Answer:

Hot Air Oven:

Component:

1. Chamber with double wall

• Inner-copper plate
• Outer – Asbestos

2. Adjustable holes – Monitor time and temperature

3. Thermostat – Regulate temperature

Hot Air Oven Time And Temperature:

• 160°C – 1 hour
• 180°C – Vz hour

Hot Air Oven Instruments That Can Be Sterilized:

• Glassware, forceps, scissors, scalpels, swabs

Hot Air Oven Precautions:

• Fitted for even distribution of air
• Not overloaded
• Arranged to allow free circulation
• Cooled for 2 hours before opening the door.

Question 2. Autoclave.

Answer:

Autoclave:

Principle:

• Water boils when its vapor pressure equals that of the surrounding atmosphere
• Steam is produced
• Autoclave condenses to water as it contacts the surface and transfers its latent heat to it.

Autoclave Time And Temperature:

• 121°C – 15 minutes at 15 lbs pressure
• 136°C – 3 minutes at 30 lbs pressure

Articles That Can Be Sterilized

• Culture media, saline, syringes, needles, dressings, gloves, aprons, gowns

Autoclave Advantages:

• Rapid
• Effective
• Good penetration

Question 3. Glass bead sterilization.

Answer:

Glass Bead sterilization:

• A rapid method of sterilization
• Salt used: 1% sodium silico-aluminate, sodium carbonate, or magnesium carbonate
• Salt is replaced by glass beads provided the beads are smaller than 1 mm in diameter as larger beads enable to transfer of heat to the endodontic instrument
• Time: 5-15 seconds, Temperature – 437 – 465°F

Glass Bead sterilization Disadvantage:

• The handle portion is not sterilized

Glass Bead sterilization Advantages:

• Economic
• Salt does not clog the root canal

Sterilisation And Infection Control Short Answers

Question 1. Autoclave

Answer:

Autoclave:

Autoclave is the process of sterilization by saturated steam under high pressure above 100 degrees C temperature

Autoclave Sterilization Conditions:

Autoclave Uses:

• Articles sterilised in autoclave are:
• Culture media
• Rubber articles like tubes, gloves, etc
• Syringes and surgical instruments
• OT gowns, dressing materials
• Endodontic instruments
• Hand instruments

Question 2. Contour.

Answer:

Contour:

• Buccal and lingual surfaces of teeth possess some degree of convexity
• Facilitate seepage of food
• Present over cervical third on facial surfaces of all the teeth, lingual surfaces of incisors, and canines.
• Middle third – On lingual surfaces of posteriors

Contour Significance:

1. Normal contour

• Shunt food toward the buccal vestibule
• Stimulate intervening tissues

2. Over contour

• Plaque accumulation
• Interferes with self-cleaning action

3. Under contour

• Opening of embrasure
• Affect the gingival

Question 3. Contacts.

Answer:

Contacts:

Contacts Significance:

• Broad Contact Faciolingually
  • Prevents seepage of food
• Broad Contact Occlusogingivally
  • Sticky food is held
  • Irritates gingiva
• Contact Located Apically
  • Packing of sticky food
  • Impinges tissue
• Contact Located Initially
  
• • Predisposes to proximal caries
  • Prevents food being pushed into embrasures
• Contact located buccally
• Loose Contact
  • Food lodgement
  • Gingival problems
  • Caries

Question 5. Embrasures.

Answer:

Embrasures:

• V-shaped spaces originating at the proximal contact area between adjacent teeth
• Types – Facial, lingual, incisal/occlusal and gingival

Embrasures Functions:

• Serve as spillways for the escape of food
• Prevents forcing the food into the contact area

Sterilisation And Infection Control Viva Voce

1. Disinfectants containing 70-90% ethyl alcohol are considered the most effective disinfectants on cleaned surfaces
2. Sterilants used for high-level disinfection of items for reuse are glutaraldehydes at 2-3 % concentrations
3. Sterilization must be tested routinely
4. Autoclave is done at 121°C temperature for 15 min at 15 lb pressure
5. Chemiclave is done at 131°C for 30 min at 20 lb pres-sure
6. Too little contour may result in trauma to the attachment apparatus
7. Improper contact can result in food impaction between teeth
8. When embrasures are decreased in size, additional stress is created on teeth
9. Lingual embrasures are usually larger than facial embrasures