Outcome 2 - Manipulate Amalgam & Bonding Agents used with it Flashcards
What is an Alloy?
The fusion of two or more pure metals
What is Amalgam?
An alloy of silver, tin, copper & sometimes zinc, combined with pure mercury
What is Amalgamation?
The uniting of the metal alloy with the mecury component
What is Condensation?
The ‘packing’ process necessary to compact the amalgam into a prepared tooth
What is Dimensional Change?
Expansion and contraction when the amalgam is exposed to heat and cold. Overexpansion of amalgam is common, resulting in pressure on the pulp, post-operative sensitivity and even protrusion of the restoration from the cavity prepartion in the tooth
What is Finishing or Carving?
Dental amalgam will remain soft enough to be carved into correct anatomical detail for several minutes after condensation. This is accomplished with various instruments known as carvers.
What is Flow or Creep?
Dimensional changes that occur when the material is warm and subject to severe biting forces. This can cause marginal breakdown or failure.
What is Marginal Failure?
Corrosion and creep allow acidic fluids from the mouth to penetrate between the restoration and surrounding tooth surface, which may allow recurrent decay or fracturing of the restoration to occur
What is Spill?
The amount of mercury dispensed by volume. Dental amalgam is supplied as either single, double, or triple spill mercury to be combined with a corresponding amount of alloy in the amalgamation process.
What is Strength of Amalgam?
Sufficient strength to resist fracture from biting forces is important. Amalgam has very little strength immediately after trituration; sufficient strength to withstand most biting forces is obtained after 24 hours. Maximum strength is obtained after 3-7 days.
What is Tarnish or Corrosion?
A surface film that produces discoloration. It may be removed by polishing if only on the surface. Once it progresses sub-surface, it may weaken the restoration.
What is Trituration?
The process of mixing the metal alloy with the mercury by vigorous shaking.
Purpose of Silver (Ag) in Amalgam?
-The main component of dental amalgam alloy per weight
-Gives the subsequent restoration its distinctive color and high luster
-Is necessary for strength and durability
-Gives the mixed amalgam density and decreased flow
-Increases the expansion of the restoration
-Decreases the setting time once mixed with mercury
Purpose of Tin (Sn) in Amalgam?
-The second component of dental amalgam allow per weight
-Added to counterbalance the rapid hardenting and high expansion properties of the silver
-Reduces the hardness that results in a brittle restoration
-Increases the workability of the mixed amalgam
Purpose of Copper (Cu) in Amalgam?
-Reduces corrosion in the restoration that often results in marginal failure
-Increases the expansion factor in the allow
-Adds to the strength and hardness of the restoration
Purpose of Zinc (Zn) in Amalgam?
-An optional metallic component of the alloy. If it is included, it is to unite with oxygen to suppress oxidation and leave the other metallic components more pure
-Alloys that contain zinc may expand excessively and corrode more readily if moisture is present prior to setting
-The resulting retoration may have overhanging margins or pressure sensation as the expansion presses the dentin toward the pulp
Dental amalgam is manufactured perdominately in what form?
In the high copper alloy form
Classification of Copper Alloys by the Shape of their particles
- Lathe-cut (irregular)
- Spherical
- Admixed
What is Lathe-cut copper alloy?
-This type of shape condenses well interproximally, keeping the matrix band firmly against the adjacent tooth
What is Spherical Copper alloy?
-these require less mercury in amalgamation, less pressure in condensation, result in a more compact & strong restoration and easily adapt to the small discrepancies and undercuts in the prepared tooth
What is Admixed Copper Alloy?
This form is a mixture of lathe-cut and spherical and combies the strength of each
The ideal restorative material is assessed using the following 11 characteristics
- Biocompatibility
- Mechanically Stable & Durable
- Resistant to Corrosion & Chemicals
- Dimensionally Stable
- Minimal Thermal & Electical Conductivity
- Esthetic
- Easy to Manipulate
- Adhesion to Tooth Tissues
- Tasteless & Odorless
- Easy to Repair and Clean
- Cost Effective
Is Amalgam Biocompatible?
There is current controversy regarding the safety of amalgam for patients as well as dental healthcare workers. With careful handling and following diposal procedures, the risk is small. At this time, the American & Canadian Dental Associations still advocate the placement of dental amalgam in posterior teeth requiring restorations when metal allergies are not a factor.
Is Amalgam Mechanically Stable & Durable?
Dental amalgam material is very hard, strong, and fracture resistant after hardening.
Is Amalgam Resistant to Corrosion and Chemicals?
Surface and marginal corrosion is a factor with dental amalgam. However, there are polishing products and procedures which can lessen the deterioration and esthetic consideration of corrosion.
Is Amalgam Dimensionally Stable?
The expansion and contraction of dental amalgam is not ideal when compared to that of tooth tissues. The expansion and contraction factor of the metal amalgam is greater than the surrounding tooth structure when exposed to hot & cold environments. This can lead to stress on the surrounding tooth structure, and possible marginal leakage between restoration and tooth.
Does Amalgam have Minimal Thermal & Electrical Conductivity?
Because dental amalgam is metal, it is a thermal and electrical conductor. The oral environment can change as much as 30 degrees C within seconds if both hot and cold foods are being consumed. There may be thermal sensitivity within the tooth, as the metal conducts the temperature towards the pulp of the tooth.
What is Galvanism/Galvanic Shock?
A condition called ‘galvanism’ or galvanic shock may occur if the amalgam is touched by a dissimilar metal and there is transference of electrical charge.
Is Amalgam Esthetically pleasing?
Ethetically, dental amalgam is not ideal. The silver colour cannot be matched to tooth structure, which eliminates the use of this material in anterior restorative situations.
Is Amalgam Easy to Manipulate?
Dental amalgam is extremely easy to manipulate and will easily conform to any shape of cavity preparation. It is very pliable after trituration and remains easy to shape and carve for a reasonable amount of time.
Does Amalgam Adhere to Tooth Tissues?
Amalgam cannot adhere to tooth structure. With the advancement of dentin bonding agents, there can be a seal created between the amalgam and tooth structure, but a not a true adhesion or bonding situation.
Is Amalgam Tasteless & Odorless?
Amalgam is tasteless and odorless and is not unpleasant once in the tooth preparation.
Is Amalgam Easy to Repair & Clean?
If the surface of the amalgam is smooth and polished, it is very easy to clean & maintain. However, if the amalgam restoration fractures or breaks down, it usually has to be fully replaced. It is difficult to add material to an exisiting restoration.
Is Amalgam Cost Effective?
The cost of dental amalgam remains the most affordable of all restorative materials currently in use. The time efficiency of placement and finishing contributes to economic benefits to the patient.
Who regulates the consumption, use & disposal of Mercury?
Because mercury can have detrimental effects on human health and the environment, its consumption, use & disposal is regulated by Environmental Canada.
Mercury can enter the body through inhalation of vapours, ingestion or absorption through the skin.
Is the mercury contained within dental amalgam stable?
It becomes stable when mixed with the silver metal alloy, which reduces its detrimental effects. Extremely small amounts of mercury can be released in the moouth under biting pressure, but this is believed to be completely harmless to patients.
Can patients be allergic to mercury?
There have been a few cases of mercury allergies (less than 0.1% of patients), which must be considered when treatment planning.
What is the most significant health concern for mercury?
The most significant concern regarding human health would be from the mercury vapour releaed during the handling of amalgam, which often impacts the dental healthcare worker more than the patient. Proper use of PPE and proper disposal will protect dental personnel from any toxic effects of the pure mercury.
Does ADA & CDA support the use of dental amalgam?
Though the safety of dental amalgam as a restorative material continues to be controversial, both the ADA & CDA still support the use of it. Amalgam continues to be a safe, affordable and durable material for posterior retorations.
What is the mercury to alloy ratio in amalgam?
Amalgam capsules are supplied in single, double, or triple spill amounts, indicating how much mercury and subsequent alloy is present in each.
The ratio is always 1:1, meaning that for each spill of mercury, there is an equal part of alloy by weight.
How much mg of alloy capsules for an amalgam single surface or small two surface restoration?
400 or 600 mg
How much mg of alloy capsule for larger restorations?
800 mg
If necessary, more than one capsule may be required for very large restorative procedures.
How is Amalgam supplied?
In plastic capsules that may or may not contain a pestle for mixing. Some amalgam capsules require activation to release the mercury into the alloy, others do not.
What is the trituration time of amalgam?
Varies by manufacturer, but ususally ranges from 5 to 20 seconds.
How do you know if amalgam is undermixed?
It will be dull, crumbly, and difficult to handle.
How do you know if amalgam is over mixed?
It will be excessively pliable and also difficult to handle.
How will you know if amalgam is correctly mixed?
Will apear cohesive, shiny, smooth and collected into a homogenous mass.
Once trituration is complete, the amalgam capsule is..
carefully opened, the amalgam dropped into an amalgam well and, if present, the pestel removed from the mass.
Standard safety precautions for handling deposing of dental amalgam falls under which Act?
Part 4 of the Canadian Environmental Protection Act, 1999
Safety Precautions for Handling Mercury - Education
All personnel involved in the handling of mercury and amalgam should be made aware of the toxic nature of these substances and should be instructed in safe handling practices.
Safety Precautions for Handling Mercury - Storage
- all mercury should be kept in tightly sealed containers
-Container should be changed approx. every 6 months. If amalgam is not used often, change annually. These sponges contain an antibacterial agent and chemical to absorb mercury molecules.
-Stored mecury and waste amalgam should be labeled, indicating the contents and hazardous nature.
Safety Precautions for Handling Mercury - Disposal Procedures for Scrap Amalgam
- the dentist should use a rubber dam when removing and placing amalgam restorations. Waste amalgam accumulated on the rubber dam can be suctioned off by the DA
- Empty amalgam capsules are placed in a Ziploc bag which is then placed into a container to be disposed of by a certified waste carrier
-Scrap amalgam bits must be placed into a break-proof sealed container until ready for disposal by a certified waste carrier.
- Op units must be equipped with disposable traps to catch waste amalgam from oral evacuation. These scrap amalgam are emptied into a sealed container and the traps are placed into Ziploc bags at the end of each amalgam procedure and then into a container for disposal by a certfied waste carrier. Use of gloves and mask when removing the suction traps for disposal
- an amalgam separator must be installed in the compressor / suction unit to prevent amalgam from entering the sewer system
The “DON’Ts” of Scrap Amalgam Handling
- do not dispose of scrap amalgam in the garbage
-do not wash scrap amalgam down the drain
-do not place scrap amalgam in the sharps container
-do not give scrap amalgam to a scrap dealer who is not certified to transport hazardous wastes
-do not rinse the traps and filters in the sink as amalgam particles will discharge into the sewer
-do not throw disposable traps that contain amalgam particles into the garbage
-do not place extracted teeth with amalgam fillings in the regular garbage. They should be disposed of in the “Scrap Amalgam” container to avoid incineration
-Do not suction up unused particles of amalgam, instead place them in a break-proof sealed container
Precautions in the Operatory for Amalgam usage
All amalgam trituration should be conducted in a ventilated area.
This triturator should be equipped with a removable tray to catch any spilled mercury or amalgam. It should be cleaned each day to free all mercury and amalgam.
During removal of amalgam restorations, dentists and D.A.s should wear a tight fitting oral-nasal mask capable of filtering out particulates. Gloves and protective eyewear must be worn.
The use of a handpiece equipped with a cooling water spray prevents frictional heating of the amalgam and subsequent release of mercury vapor during removal of the restorations from the patient’s mouth.
All surfaces where mercury and amalgam are used should be free of cracks or corners where mercury can be trapped.
Floors should be one piece with corners and abutting walls covered.
Carpets should not be used in operatories because it is almost impossible to decontaminate them from a mercury spill. Further more, vacuuming of mercury from contaminated carpets can create a temporary severe inhalation hazard because the mercury, passing through the heated exhaust of the vacuum cleaner, is readily vaporized.
Operatory chairs should be covered with a smooth vinyl upholstery material. Cloth coverings should be avoided.
Excess amalgam should not be permitted to fall from the patient’s clothing because it can contaminate operatory floors, dental chairs, and floors.
Mercury contamination can be eliminated during handling of the metal if encapsulated pre-proportioned materials are used when the amalgam is being prepared.
Manufacturer’s recommendations with respect to maximum quantities of materials to be used in their triturators should be followed.
Load your carrier from an amalgam well or a dappen dish
How to clean up mercury spill
- clean up spills immediately using an approved mercury spill kit
-never use bare hands to gather up spilled mercury
-all materials used for picking up spills should be collected and stored for disposal
Personal Hygiene for Mercury
-If mercury or amalgam is accidentally touched with your hands, scrub them thoroughly using soap or detergent as soon as possible.
-Smoking or eating should be prohibited in areas where mercury is used, and persons who have worked with mercury should not smoke or eat until they have washed.
-Mercury may be absorbed from contaminated clothing. Lab coats, plastic aprons, or coveralls should be worn where clothing contamination is likely.
Persons working with mercury should consult with their physician if one or more of the following signs or symptoms occur:
Soreness, inflammation or bleeding of the gums, loosening of teeth, metallic taste in the mouth
Tremor or shaking of the hands, tongue, lips, head or extremities
Change in personality; particularly if unusually irritable or excitable, if unusual difficulty is experienced in getting along with others, or if moods change frequently for no apparent reason
Loss of appetite, weakness, digestive disorders, sore mouth, excessive salivation
