This document provides an overview of dental amalgam, including:
- A brief history of amalgam, noting its first uses dating back to the 7th century and widespread adoption starting in the 19th century.
- Details on the "amalgam wars" that occurred over concerns about the safety of mercury in amalgam in the 19th and 20th centuries.
- Descriptions of the composition, manufacturing processes, phases and properties of amalgam, as well as newer advances and ongoing controversies.
- It concludes by restating amalgam's position as one of the most commonly used dental restorative materials historically, while acknowledging alternatives and declining use due to safety questions.
The document discusses dental ceramics, including their history, structure, composition, and classification. Some key points:
- Dental ceramics have been used since ancient times, with early developments including porcelain teeth in the late 18th century. Major advances included reinforced porcelains in the 1960s and all-ceramic systems in the 1980s-1990s.
- Ceramics can be crystalline or non-crystalline (glass). Dental ceramics are mainly composed of crystalline minerals and a glass matrix. Common components include feldspar, silica, kaolin, and glass modifiers.
- Ceramics are classified as non-crystalline or crystalline, with fel
A comprehensive lecture by Dr Rashid Hassan covering all the aspects of different types of model and die materials. Easy ti understand ans recall.
For video lectures on different topics of Dental Materials visit and follow Dr Rashid Lectures on Dental Materials (dmbydrrashid) on Facebook.
This document provides an overview of dental ceramics. It defines ceramics as inorganic compounds formed from metallic, semi-metallic, and nonmetallic elements that are subjected to high heat. Dental ceramics are commonly used for crowns, bridges, inlays and other restorations. They are composed mainly of feldspars, quartz, and kaolin that undergo firing and produce a vitreous glassy phase and crystalline phase. Dental ceramics are strengthened through various techniques to increase their durability for use in load-bearing applications in the mouth.
Contents of this slide
Introduction
Terminologies
History
Classification
Composition
Methods of Strengthening Ceramics.
Metal-Ceramic restorations
All Ceramic restorations
Mechanical and thermal properties of dental ceramics.
Optical properties of dental ceramics.
Porcelain Denture Teeth
Factors affecting the Color of Ceramics.
Recent advancements.
Conclusion & References.
This document discusses the history, composition, production, and properties of dental amalgam. It begins with a brief history of amalgam use in dentistry dating back to the 1800s. It then discusses the components of amalgam alloys including mercury, silver, tin, and copper. The document outlines the production methods for lathe-cut and spherical alloy powders. It describes the metallurgical phases that form during amalgamation and how they contribute to properties like strength, creep, corrosion resistance and dimensional stability. Overall, the document provides a comprehensive overview of dental amalgam materials.
The document provides a history of denture materials and techniques from ancient times to modern day. It begins with early dentures made of materials like wood, bone, ivory and human teeth. Important developments include the introduction of porcelain and vulcanite dentures in the 18th-19th centuries. In the 1930s, polymethyl methacrylate (PMMA) was introduced and became the standard denture material due to its strength, biocompatibility and ease of use. The document also describes the compression molding technique for fabricating PMMA dentures, involving steps like flasking, packing, curing and finishing. Alternative techniques like injection molding are also mentioned.
Ceramics have many applications in dentistry due to their esthetic qualities, strength, and biocompatibility. Ceramics are used in crowns, bridges, veneers, dentures, and more. There are several types of ceramics including metal-ceramics, which combine a ceramic material fused to a metal framework for strength, and all-ceramic options made of materials like alumina and zirconia. Ceramic materials are fabricated through processes like sintering, heat pressing, slip-casting, and CAD/CAM milling. Ceramics provide natural-looking and long-lasting restorations but also have limitations like brittleness which new materials continue to address
The document provides information on the procedure for amalgam restoration. It discusses the appropriate mercury to alloy ratio, which is typically 1:1. It describes the steps of trituration to mix the alloy and mercury using either hand mixing or mechanical mixing. Proper trituration is important to coat the alloy particles. The document also outlines the steps for condensing the amalgam into the cavity preparation using incremental layering and discusses carving and polishing the final restoration.
The document discusses dental ceramics, including their history, structure, composition, and classification. Some key points:
- Dental ceramics have been used since ancient times, with early developments including porcelain teeth in the late 18th century. Major advances included reinforced porcelains in the 1960s and all-ceramic systems in the 1980s-1990s.
- Ceramics can be crystalline or non-crystalline (glass). Dental ceramics are mainly composed of crystalline minerals and a glass matrix. Common components include feldspar, silica, kaolin, and glass modifiers.
- Ceramics are classified as non-crystalline or crystalline, with fel
A comprehensive lecture by Dr Rashid Hassan covering all the aspects of different types of model and die materials. Easy ti understand ans recall.
For video lectures on different topics of Dental Materials visit and follow Dr Rashid Lectures on Dental Materials (dmbydrrashid) on Facebook.
This document provides an overview of dental ceramics. It defines ceramics as inorganic compounds formed from metallic, semi-metallic, and nonmetallic elements that are subjected to high heat. Dental ceramics are commonly used for crowns, bridges, inlays and other restorations. They are composed mainly of feldspars, quartz, and kaolin that undergo firing and produce a vitreous glassy phase and crystalline phase. Dental ceramics are strengthened through various techniques to increase their durability for use in load-bearing applications in the mouth.
Contents of this slide
Introduction
Terminologies
History
Classification
Composition
Methods of Strengthening Ceramics.
Metal-Ceramic restorations
All Ceramic restorations
Mechanical and thermal properties of dental ceramics.
Optical properties of dental ceramics.
Porcelain Denture Teeth
Factors affecting the Color of Ceramics.
Recent advancements.
Conclusion & References.
This document discusses the history, composition, production, and properties of dental amalgam. It begins with a brief history of amalgam use in dentistry dating back to the 1800s. It then discusses the components of amalgam alloys including mercury, silver, tin, and copper. The document outlines the production methods for lathe-cut and spherical alloy powders. It describes the metallurgical phases that form during amalgamation and how they contribute to properties like strength, creep, corrosion resistance and dimensional stability. Overall, the document provides a comprehensive overview of dental amalgam materials.
The document provides a history of denture materials and techniques from ancient times to modern day. It begins with early dentures made of materials like wood, bone, ivory and human teeth. Important developments include the introduction of porcelain and vulcanite dentures in the 18th-19th centuries. In the 1930s, polymethyl methacrylate (PMMA) was introduced and became the standard denture material due to its strength, biocompatibility and ease of use. The document also describes the compression molding technique for fabricating PMMA dentures, involving steps like flasking, packing, curing and finishing. Alternative techniques like injection molding are also mentioned.
Ceramics have many applications in dentistry due to their esthetic qualities, strength, and biocompatibility. Ceramics are used in crowns, bridges, veneers, dentures, and more. There are several types of ceramics including metal-ceramics, which combine a ceramic material fused to a metal framework for strength, and all-ceramic options made of materials like alumina and zirconia. Ceramic materials are fabricated through processes like sintering, heat pressing, slip-casting, and CAD/CAM milling. Ceramics provide natural-looking and long-lasting restorations but also have limitations like brittleness which new materials continue to address
The document provides information on the procedure for amalgam restoration. It discusses the appropriate mercury to alloy ratio, which is typically 1:1. It describes the steps of trituration to mix the alloy and mercury using either hand mixing or mechanical mixing. Proper trituration is important to coat the alloy particles. The document also outlines the steps for condensing the amalgam into the cavity preparation using incremental layering and discusses carving and polishing the final restoration.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
This document provides an overview of gutta percha, including its discovery, historical uses, sources, evolution in dentistry, composition, chemistry, phases, properties, and commercial manufacture. Gutta percha is a natural polymer that has been used in dentistry as a root canal filling material since the 19th century due to its biocompatibility and ability to adapt to canal walls and provide a fluid-tight seal at the apex. It exists in alpha and beta crystalline forms that impact its viscosity and handling properties for different obturation techniques.
This document discusses the history and composition of dental amalgam. It describes the three "amalgam wars" where the safety of amalgam was debated. Amalgam is an alloy of silver, tin, copper and sometimes other metals like zinc. The document outlines the different generations of amalgam alloys and how composition affects properties. High copper alloys aim to improve strength and corrosion resistance over traditional low copper alloys. Both admixed and unicompositional high copper alloys are discussed in terms of their microstructure and reaction with mercury during setting. The physical properties of dimensional stability, strength and corrosion resistance are also summarized.
This document discusses acid etching of dental surfaces. It describes how acid etching was first proposed in 1955 to increase bond strength between composite resin and enamel. Acid etching removes enamel and creates an irregular porous surface that allows resin to penetrate through micromechanical interlocking, improving bond strength. Factors like acid type/concentration, etching duration, and fluoride levels can affect bonding. While acid etching is effective, some alternatives under investigation include crystal growth solutions, air abrasion, and lasers, but they have not achieved bond strengths as high as acid etching.
This document discusses glass ionomer cement and resin-modified glass ionomer cement in restorative dentistry. It describes the composition and setting reactions of glass ionomer cement, as well as its advantages like adhesion to tooth structure, fluoride release, and low shrinkage. However, it also notes disadvantages like poorer wear resistance and physical properties compared to resin composites, as well as ongoing moisture sensitivity issues. The document then discusses how resin-modified glass ionomer cements were developed to improve properties like strength and reduce moisture sensitivity issues. It concludes by describing clinical applications of resin-modified glass ionomer cements, such as for class V restorations, root caries treatment, and the sandwich technique.
An impression in complete dentures is a negative registration of the denture bearing areas made of a material that sets in the mouth. There are different types of impressions based on theories, techniques, trays, and materials used. The objectives of making an impression are to preserve remaining structures, provide retention, stability, support and esthetics. A stock or custom tray is used depending on needs, and materials must be dimensionally stable and reproduce anatomical details accurately.
Kennedy’s Classification in Cast Partial DentureAamir Godil
This document discusses Kennedy's classification system for partially edentulous arches and Applegate's rules for applying the Kennedy classification. It provides details on Kennedy's four basic classes for partial edentulism and Applegate's eight rules to govern the application of Kennedy's classification. Examples are given to demonstrate how to use Kennedy's classification and Applegate's rules to classify different clinical scenarios of partial edentulism.
Zinc oxide eugenol impression paste sets via an irreversible chemical reaction between zinc oxide and eugenol to form zinc eugenolate. It has good detail reproduction and dimensional stability but can cause a burning sensation. It is mixed in equal volumes of zinc oxide paste and eugenol paste on a mixing slab until uniformly colored, and has a working time of about 1 minute before initial set. Variations include slower-setting surgical pastes and non-eugenol pastes that avoid the burning sensation.
This document provides an overview of dental amalgam, including its history, composition, manufacturing process, properties, and clinical use. Dental amalgam is an alloy made by mixing mercury with a silver-tin alloy. It has been used as a dental restorative material since the 1800s. The document discusses the various types of amalgam alloys, the chemical reactions involved in amalgam setting, and how properties like strength and creep vary between low-copper and high-copper amalgam formulations. It also outlines the indications and contraindications for using dental amalgam.
This document provides information on various types of dental waxes. It begins with definitions of waxes in general and an introduction to dental waxes. It then describes the typical composition of dental waxes which includes a base wax, modifiers, and colorants. Several types of dental waxes are discussed, including pattern waxes for inlays, castings, and baseplates as well as processing waxes for tasks like boxing and utility uses. The document concludes with a brief section on impression waxes used for bite registration and corrections.
The document provides information on dental amalgam, including its composition, manufacturing process, properties, uses and classifications. It discusses the key components of amalgam alloys such as silver, tin, copper and mercury. It also describes the various metallurgical phases that form in amalgam, including the gamma and gamma-2 phases. Furthermore, it covers the history of amalgam and the different "amalgam wars" that occurred over the use of dental amalgam. The manufacturing process for alloy powders, including lathe-cut and atomized methods, is also summarized.
A record base or baseplate is a temporary form representing the base of a denture. It is used in recording maxillomandibular relations and in the arrangement of teeth. There are various materials that can be used to fabricate a baseplate including auto polymerizing resin, shellac, vacuum formed materials, wax and heat cure acrylic resin. The proper fabrication method must be selected based on the material. Common problems encountered include baseplates that are too thin, thick or flexible. The causes and solutions to issues are discussed.
This document provides information on alginate impression material. It defines alginate as an irreversible hydrocolloid impression material made from seaweed. It discusses the composition, setting reaction, and physical phases of alginate. The document also outlines the manipulation, application, advantages and disadvantages of alginate impression material.
The document discusses dental amalgam, including its historical background, composition, manufacturing process, phases, kinetics of amalgamation, manipulation factors, properties, and alternatives. It provides details on the alloy manufacturing process, phases that form in amalgam, the kinetics of how amalgam sets, and factors that influence manipulating the amalgam mix, such as choice of alloy, mercury, and trituration method. It also outlines the properties of set amalgam, including its dimensional changes, strengths, corrosion resistance, and thermal properties.
GLASS IONOMER CEMENT AND ITS RECENT ADVANCES- by Dr. JAGADEESH KODITYALAJagadeesh Kodityala
This document provides an overview of glass ionomer cement, including its definition, history, composition, classification, setting reaction, properties, and recent advances. Key points include:
- Glass ionomer cement was invented in 1969 and first reported in 1971, consisting of a glass powder and aqueous solution of polyacrylic acid.
- It is classified based on its intended use, such as luting cement, restorative cement, or liner/base material.
- The setting reaction involves an acid-base reaction between the glass powder and polyacrylic acid, forming bonds through a calcium polyacrylate matrix that continues to harden over time.
- Properties include adhesion to tooth structure, biocompatibility, fluoride
Zinc polycarboxylate cement sets through an acid-base reaction between zinc oxide and polyacrylic acid. It exists as a powder containing zinc oxide, magnesium oxide, and polyacrylic acid, and as a liquid containing polyacrylic acid and water. The powder and liquid are mixed together, with the polyacrylic acid chelating with the zinc oxide to form a matrix of zinc polyacrylate salt surrounded by undispersed zinc oxide particles. Zinc polycarboxylate cement has mechanical strength comparable to zinc phosphate cement, adheres chemically to tooth structure and metals, and has a film thickness similar to zinc phosphate cement. It is less irritating to the pulp than zinc phosphate cement due to becoming
The document discusses dental casting alloys, including their history, desirable properties, composition, classification into noble metal alloys and base metal alloys. Key points covered include the importance of biocompatibility, corrosion resistance, aesthetics and thermal properties of alloys. Common metals used in alloys such as gold, palladium, silver and nickel are described.
Amalgam dental ppt for dental material studyPriyankaIppar
Dental amalgam is an alloy used in dental fillings that contains mercury and other metals such as silver, tin, and copper. It has been used for over 165 years but concerns over mercury safety and the development of alternative materials like composites have led to its decline. The document discusses the history of amalgam, including its first documented use in 659 AD by the Chinese and major developments in the 19th and 20th centuries. It also covers the composition of amalgam alloys, their manufacturing process, and the ongoing debate around the use of amalgam known as the "amalgam wars."
Stainless steel crowns are prefabricated crown forms that are adapted to individual teeth and cemented with a biocompatible luting agent. “The SSC is extremely durable, relatively inexpensive, subject to minimal technique sensitivity during placement, and offers the advantage of full coronal coverage.”
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
This document provides an overview of gutta percha, including its discovery, historical uses, sources, evolution in dentistry, composition, chemistry, phases, properties, and commercial manufacture. Gutta percha is a natural polymer that has been used in dentistry as a root canal filling material since the 19th century due to its biocompatibility and ability to adapt to canal walls and provide a fluid-tight seal at the apex. It exists in alpha and beta crystalline forms that impact its viscosity and handling properties for different obturation techniques.
This document discusses the history and composition of dental amalgam. It describes the three "amalgam wars" where the safety of amalgam was debated. Amalgam is an alloy of silver, tin, copper and sometimes other metals like zinc. The document outlines the different generations of amalgam alloys and how composition affects properties. High copper alloys aim to improve strength and corrosion resistance over traditional low copper alloys. Both admixed and unicompositional high copper alloys are discussed in terms of their microstructure and reaction with mercury during setting. The physical properties of dimensional stability, strength and corrosion resistance are also summarized.
This document discusses acid etching of dental surfaces. It describes how acid etching was first proposed in 1955 to increase bond strength between composite resin and enamel. Acid etching removes enamel and creates an irregular porous surface that allows resin to penetrate through micromechanical interlocking, improving bond strength. Factors like acid type/concentration, etching duration, and fluoride levels can affect bonding. While acid etching is effective, some alternatives under investigation include crystal growth solutions, air abrasion, and lasers, but they have not achieved bond strengths as high as acid etching.
This document discusses glass ionomer cement and resin-modified glass ionomer cement in restorative dentistry. It describes the composition and setting reactions of glass ionomer cement, as well as its advantages like adhesion to tooth structure, fluoride release, and low shrinkage. However, it also notes disadvantages like poorer wear resistance and physical properties compared to resin composites, as well as ongoing moisture sensitivity issues. The document then discusses how resin-modified glass ionomer cements were developed to improve properties like strength and reduce moisture sensitivity issues. It concludes by describing clinical applications of resin-modified glass ionomer cements, such as for class V restorations, root caries treatment, and the sandwich technique.
An impression in complete dentures is a negative registration of the denture bearing areas made of a material that sets in the mouth. There are different types of impressions based on theories, techniques, trays, and materials used. The objectives of making an impression are to preserve remaining structures, provide retention, stability, support and esthetics. A stock or custom tray is used depending on needs, and materials must be dimensionally stable and reproduce anatomical details accurately.
Kennedy’s Classification in Cast Partial DentureAamir Godil
This document discusses Kennedy's classification system for partially edentulous arches and Applegate's rules for applying the Kennedy classification. It provides details on Kennedy's four basic classes for partial edentulism and Applegate's eight rules to govern the application of Kennedy's classification. Examples are given to demonstrate how to use Kennedy's classification and Applegate's rules to classify different clinical scenarios of partial edentulism.
Zinc oxide eugenol impression paste sets via an irreversible chemical reaction between zinc oxide and eugenol to form zinc eugenolate. It has good detail reproduction and dimensional stability but can cause a burning sensation. It is mixed in equal volumes of zinc oxide paste and eugenol paste on a mixing slab until uniformly colored, and has a working time of about 1 minute before initial set. Variations include slower-setting surgical pastes and non-eugenol pastes that avoid the burning sensation.
This document provides an overview of dental amalgam, including its history, composition, manufacturing process, properties, and clinical use. Dental amalgam is an alloy made by mixing mercury with a silver-tin alloy. It has been used as a dental restorative material since the 1800s. The document discusses the various types of amalgam alloys, the chemical reactions involved in amalgam setting, and how properties like strength and creep vary between low-copper and high-copper amalgam formulations. It also outlines the indications and contraindications for using dental amalgam.
This document provides information on various types of dental waxes. It begins with definitions of waxes in general and an introduction to dental waxes. It then describes the typical composition of dental waxes which includes a base wax, modifiers, and colorants. Several types of dental waxes are discussed, including pattern waxes for inlays, castings, and baseplates as well as processing waxes for tasks like boxing and utility uses. The document concludes with a brief section on impression waxes used for bite registration and corrections.
The document provides information on dental amalgam, including its composition, manufacturing process, properties, uses and classifications. It discusses the key components of amalgam alloys such as silver, tin, copper and mercury. It also describes the various metallurgical phases that form in amalgam, including the gamma and gamma-2 phases. Furthermore, it covers the history of amalgam and the different "amalgam wars" that occurred over the use of dental amalgam. The manufacturing process for alloy powders, including lathe-cut and atomized methods, is also summarized.
A record base or baseplate is a temporary form representing the base of a denture. It is used in recording maxillomandibular relations and in the arrangement of teeth. There are various materials that can be used to fabricate a baseplate including auto polymerizing resin, shellac, vacuum formed materials, wax and heat cure acrylic resin. The proper fabrication method must be selected based on the material. Common problems encountered include baseplates that are too thin, thick or flexible. The causes and solutions to issues are discussed.
This document provides information on alginate impression material. It defines alginate as an irreversible hydrocolloid impression material made from seaweed. It discusses the composition, setting reaction, and physical phases of alginate. The document also outlines the manipulation, application, advantages and disadvantages of alginate impression material.
The document discusses dental amalgam, including its historical background, composition, manufacturing process, phases, kinetics of amalgamation, manipulation factors, properties, and alternatives. It provides details on the alloy manufacturing process, phases that form in amalgam, the kinetics of how amalgam sets, and factors that influence manipulating the amalgam mix, such as choice of alloy, mercury, and trituration method. It also outlines the properties of set amalgam, including its dimensional changes, strengths, corrosion resistance, and thermal properties.
GLASS IONOMER CEMENT AND ITS RECENT ADVANCES- by Dr. JAGADEESH KODITYALAJagadeesh Kodityala
This document provides an overview of glass ionomer cement, including its definition, history, composition, classification, setting reaction, properties, and recent advances. Key points include:
- Glass ionomer cement was invented in 1969 and first reported in 1971, consisting of a glass powder and aqueous solution of polyacrylic acid.
- It is classified based on its intended use, such as luting cement, restorative cement, or liner/base material.
- The setting reaction involves an acid-base reaction between the glass powder and polyacrylic acid, forming bonds through a calcium polyacrylate matrix that continues to harden over time.
- Properties include adhesion to tooth structure, biocompatibility, fluoride
Zinc polycarboxylate cement sets through an acid-base reaction between zinc oxide and polyacrylic acid. It exists as a powder containing zinc oxide, magnesium oxide, and polyacrylic acid, and as a liquid containing polyacrylic acid and water. The powder and liquid are mixed together, with the polyacrylic acid chelating with the zinc oxide to form a matrix of zinc polyacrylate salt surrounded by undispersed zinc oxide particles. Zinc polycarboxylate cement has mechanical strength comparable to zinc phosphate cement, adheres chemically to tooth structure and metals, and has a film thickness similar to zinc phosphate cement. It is less irritating to the pulp than zinc phosphate cement due to becoming
The document discusses dental casting alloys, including their history, desirable properties, composition, classification into noble metal alloys and base metal alloys. Key points covered include the importance of biocompatibility, corrosion resistance, aesthetics and thermal properties of alloys. Common metals used in alloys such as gold, palladium, silver and nickel are described.
Amalgam dental ppt for dental material studyPriyankaIppar
Dental amalgam is an alloy used in dental fillings that contains mercury and other metals such as silver, tin, and copper. It has been used for over 165 years but concerns over mercury safety and the development of alternative materials like composites have led to its decline. The document discusses the history of amalgam, including its first documented use in 659 AD by the Chinese and major developments in the 19th and 20th centuries. It also covers the composition of amalgam alloys, their manufacturing process, and the ongoing debate around the use of amalgam known as the "amalgam wars."
Stainless steel crowns are prefabricated crown forms that are adapted to individual teeth and cemented with a biocompatible luting agent. “The SSC is extremely durable, relatively inexpensive, subject to minimal technique sensitivity during placement, and offers the advantage of full coronal coverage.”
Dental amalgam has been used as a dental restoration material for over 165 years. It is an alloy made by mixing mercury with a silver-tin alloy powder. Amalgam has been the subject of controversy since the 19th century over its safety. However, recent studies and statements by organizations like the ADA and FDA indicate that amalgam is a safe, cost-effective, and long-lasting restorative material when used properly. Newer amalgam alloys have been developed with improved properties like reduced creep and corrosion. While alternatives like composites are growing in use, amalgam remains a valuable option for restoring teeth.
This document provides an overview of dental amalgam. It begins with a brief introduction, then discusses the history of amalgam use dating back to ancient China. The document outlines various classifications of amalgam and lists indications and contraindications for its use. Advantages include ease of use and strength, while disadvantages include esthetics and weakness of tooth structure. The document discusses the composition of amalgam, including the roles of individual components like silver, tin and copper. It also summarizes the amalgamation reaction and properties of amalgam like strength, creep and corrosion resistance.
Dental amalgam is a dental restorative material made of a mixture of metals like silver, tin, and copper combined with mercury. It has been used for over 175 years due to its durability, ease of use, and low cost. While amalgam restorations were previously widely used, their use has declined by 45% in the last 20 years due to concerns about safety and aesthetics. Modern high-copper amalgam alloys are considered safe and have better strength and corrosion resistance than older low-copper formulations. When the alloy particles are mixed with mercury, a chemical reaction called amalgamation occurs, forming the dental amalgam used in restorations.
Dental amalgam2 / rotary endodontic courses by indian dental academyIndian dental academy
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
This document reviews implant biomaterials from ancient times to present. It discusses early implants made of stone, ivory and metals. In the modern era, materials include polymers, cobalt-chromium alloys, titanium and its alloys, zirconia and newer titanium-zirconium alloys. Key properties for implant materials are reviewed like strength, corrosion resistance and biocompatibility. The document concludes that while significant advancements have been made in dental implants, further research is still needed.
Stainless steel crowns in paediatric dentistryDr Ravneet Kour
Stainless steel crowns are commonly used in pediatric dentistry to restore heavily decayed primary molars. They have a long history of use dating back to the 1940s. There are different types based on composition and morphology. Indications include restoring teeth with extensive decay involving multiple surfaces. Contraindications include teeth with advanced root resorption. Placement involves tooth preparation, crown selection, adaptation and cementation. Potential complications include aspiration during placement and nickel allergy in some patients.
Dental amalgam is a dental filling material composed of a mixture of metals including liquid mercury and a powdered alloy of silver, tin, and copper. Approximately half of dental amalgam is mercury by weight. Mercury binds the alloy particles together to form a strong, durable filling. While dental amalgam has been used widely for over 150 years, it also has some disadvantages such as its gray color, potential toxicity from mercury, and lack of bonding to tooth structure. Liners and bases are often used under amalgam fillings to reduce post-operative sensitivity and act as a protective buffer layer.
Metal free ceramics /certified fixed orthodontic courses by Indian dental aca...Indian dental academy
This document discusses various types of dental ceramics, including their composition, properties and uses. It describes porcelain and glass ceramics, noting that porcelain is a ceramic material formed from infusible elements joined by lower fusing material. The document outlines the history of dental ceramics and provides classifications including types, uses, processing methods and substructure materials. It also compares metal ceramics to all-ceramic systems, discussing advantages and disadvantages of each.
This document discusses various types of dental ceramics, including their composition, properties and uses. It describes porcelain and glass ceramics, noting that porcelain is formed from infusible elements joined by lower fusing material. The history of dental ceramics is reviewed from early uses of human, animal and ivory teeth to modern porcelain and glass formulations. Advantages of all-ceramic restorations over metal-ceramic are listed. Classification systems for dental ceramics include type, use, processing method and substructure material. Properties like strength and factors affecting it are also covered.
Stainless steel crowns in pediatric dentistry pptdrvinodini
This document provides an overview of stainless steel crowns (SSCs), including their history, composition, indications, contraindications, placement procedure, and modifications. SSCs were first described in 1950 as a semi-permanent restoration option for primary and young permanent teeth. They are made of stainless steel or nickel-chromium alloys. SSCs are indicated for restoring teeth with extensive decay, fractures, pulpotomies, or as a space maintainer. Placement involves tooth preparation, selection and fitting of the crown, contouring, crimping, cementation, and finishing. Modifications include altering crown size or adding material to accommodate deep caries or spacing issues. Studies have found SSCs to have low microleakage and
Metal free ceramics /certified fixed orthodontic courses by Indian dental aca...Indian dental academy
This document provides information on metal-free ceramics used in dentistry. It defines ceramics as compounds containing metals and nonmetals like oxygen. Porcelain is a ceramic material formed from infusible elements joined by lower-fusing materials. All-ceramic restorations without metal substructures have better esthetics than metal-ceramic options. The document discusses the history and development of dental ceramics from the 18th century to modern systems. It also classifies and describes different ceramic types like feldspathic porcelain, alumina, and glass ceramics as well as processing methods.
This document discusses stainless steel crowns, which are semi-permanent restorations used in primary and young permanent teeth. It describes the history, types, indications, advantages, disadvantages, composition, placement procedure, modifications, and complications of stainless steel crowns. Stainless steel crowns provide full tooth coverage and are effective for restoring extensively decayed or malformed primary teeth. They are durable, economical restorations that can improve function and aesthetics for young patients.
presentation includes the history of amalgam from its very first use to the present day situation, classification, advantages, disadvantages, properties, functions and manipulation of dental amalgam
The document provides an overview of dental amalgam, including:
- A definition of amalgam as an alloy containing mercury
- A history of amalgam use dating back to the 15th century
- Classification of amalgams by alloy composition and particle shape
- The setting reaction when mercury is mixed with alloy particles to form phases like gamma, gamma-1, and gamma-2
- Properties of set amalgam addressed in ADA specifications like strength, dimensional change, and creep
Cavity preparation for cast metal restorationschatupriya
This document discusses cavity preparation for cast metal restorations. It begins by introducing cast metal restorations and their history. It then defines inlays and onlays. The document discusses various materials used for cast restorations including gold, platinum, and nickel-chromium alloys. It covers the requirements, properties, and classes of different dental casting alloys. The document provides details on cavity preparation principles, outline forms, and features to provide resistance and retention. It also discusses preparation modifications and secondary retention methods.
This document provides information on various types of posterior dental restorations including amalgam, glass ionomer cements, and composites. It discusses the composition, classification, setting reactions, properties, and applications of each material type. For amalgam, it describes the different alloy classifications and compositions as well as the setting reactions for low copper versus high copper alloys. For glass ionomer cements, it outlines the components, setting reactions, classifications including for luting, restorative, and liner/base applications, and properties including thermal compatibility and anticariogenicity from fluoride release. Examples of applications for glass ionomer cements include the sandwich technique, pit and fissure sealants, tunnel preparations, and core buildups.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
This document provides information on cavity preparation for cast metal restorations. It discusses various types of cast restorations like inlays and onlays. Key points include:
- Different classes of casting alloys are described based on their composition, such as gold-based, low gold, non-gold platinum and nickel-chromium alloys.
- Principles of cavity preparation include following tooth anatomy, maintaining resistance and retention forms, and preparing cavities with resistance and retention features like dovetails.
- Specific burs and techniques are outlined for preparing cavities in molars and premolars, including maintaining proper cavity depth, taper, and finishing line placement.
Muktapishti is a traditional Ayurvedic preparation made from Shoditha Mukta (Purified Pearl), is believed to help regulate thyroid function and reduce symptoms of hyperthyroidism due to its cooling and balancing properties. Clinical evidence on its efficacy remains limited, necessitating further research to validate its therapeutic benefits.
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- Video recording of this lecture in English language: https://youtu.be/kqbnxVAZs-0
- Video recording of this lecture in Arabic language: https://youtu.be/SINlygW1Mpc
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
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Basavarajeeyam is a Sreshta Sangraha grantha (Compiled book ), written by Neelkanta kotturu Basavaraja Virachita. It contains 25 Prakaranas, First 24 Chapters related to Rogas& 25th to Rasadravyas.
8 Surprising Reasons To Meditate 40 Minutes A Day That Can Change Your Life.pptxHolistified Wellness
We’re talking about Vedic Meditation, a form of meditation that has been around for at least 5,000 years. Back then, the people who lived in the Indus Valley, now known as India and Pakistan, practised meditation as a fundamental part of daily life. This knowledge that has given us yoga and Ayurveda, was known as Veda, hence the name Vedic. And though there are some written records, the practice has been passed down verbally from generation to generation.
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of the physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
6. Describe the flow of current around the heart during the cardiac cycle
7. Discuss the placement and polarity of the leads of electrocardiograph
8. Describe the normal electrocardiograms recorded from the limb leads and explain the physiological basis of the different records that are obtained
9. Define mean electrical vector (axis) of the heart and give the normal range
10. Define the mean QRS vector
11. Describe the axes of leads (hexagonal reference system)
12. Comprehend the vectorial analysis of the normal ECG
13. Determine the mean electrical axis of the ventricular QRS and appreciate the mean axis deviation
14. Explain the concepts of current of injury, J point, and their significance
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
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• Pitfalls and pivots needed to use AI effectively in public health
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• Assessing risk and mitigating harm from adverse health narratives in communities, health workforce and health system
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dental amalgam material aspects
1. Dr. Anita Dsouza
3rd MDS
Department of Conservative Dentistry and
Endodontics
DENTAL AMALGAM
MATERIAL ASPECTS
2. CONTENTS
• INTRODUCTION
• HISTORY
• AMALGAM WARS
• ADA SPECIFICATION
• CLASSIFICATION
• INDICATIONS AND CONTRAINDICATIONS
• ADVANTAGES AND DISADVANTAGES
• COMPOSITION
• MANUFACTURING PROCESS
• PHASES
• METALLURGIC PROCESSES
• PROPERTIES
• NEWER ADVANCES
• CONTROVERSIES
• CONCLUSION
• REFERENCES
3. Dental amalgam is one of the most
versatile restorative materials used in
dentistry.
It constitutes approximately 75% of all
restorative materials used by dentists.
It has served as a dental restoration for more
than 165 years.
4.
5. • over the last few years, improvements in composition
have led to:
REDUCED
MARGINAL
CORROSION DUE
TO DECREASED
CREEP AND
CORROSION
EARLY SEAL
BETWEEN
TOOTH AND
RESTORATION
But development of alternatives based on ceramics and
composites , and questions on its safety have led to its
decline.
6. AMALGAM
• Amalgam -An alloy containing mercury
• Dental Amalgam – An alloy of mercury silver copper and tin,
which may also contain palladium, zinc and other elements
to improve handling characteristics and clinical
performance
• Dental amalgam Alloy – An alloy of silver copper and tin
that is formulated and processed in the form of powder
particles or compressed pellets.
Phillips’ Science of dental materials, 11/e Anusavice.
7. • Amalgam -- First used by Chinese. There is a mention of
silver mercury paste by Sukung (659AD) in the Chinese
medicine and later by Li schichan
• First use of room temp mixed amalgam- Bell in England
1819 (Bell’s putty)
• Traveau in France (1826) – advocated a mixture of silver
and mercury as a filling material – produced amalgam by
grinding silver coins with mercury.
• 1833 – Introduction of Royal Mineral Succedaneum to USA
as substitute for gold – Crawcour Brothers- “Royal mineral
succedaneum”
8. • 1840s– AMALGAM WAR
• 1859- ADA was formed
• 1860’S -1870’S – Elisa townsend and Flagg did a lot of
work to improve Dental Amalgam
• 1895- To overcome expansion problems G.V. Black
developed a formula for modern amalgam alloy -67%
silver, 27% tin, 5% copper, 1% zinc
• 1920 – Dr Grey – Delayed expansion
• 1926 - Second amalgam war – Europe – as a result of
the writings of Alfred Stock, a professor of Chemistry
published papers on the dangers of mercury vapor
9. • 1937- Gaylerin found that in the coarse filling alloys of that
time, copper contents greater than 6% produced excessive
expansion
• This was later challenged by Greener in 1970’S
• 1946 - Skinner, added copper to the amalgam alloy
composition in a small amount. This served to increase
strength and decrease flow
• 1959 – Dr. Wilmer Eames recommended a 1:1 ratio of
mercury to alloy, thus lowering the 8:5 ratio of mercury to
alloy that others had recommended.
• 1962- spherical particle dental alloy was introduced by Innes
& Youdelis
10. • 1963 – Innes and Youdelis – High Cu admixed alloy
• 1970- Change from hand trituration to mechanical trituration
• 1973 - Current controversy – termed Third amalgam war –
due to writings of Dr HA Higgins
• 1973 - First single composition spherical alloy named Tytin
(Kerr) a ternary system (silver/tin/copper) was discovered by
Kamal Asgar of the University of Michigan
• 1979 – Gay and workers found mercury vapor in breath of
patients with amalgam fillings following chewing.
11. • 1984- human autopsy demonstrated the mercury found in brain
and kidneys were related to the amalgam fillings in the teeth.
• 1990- media was involved when the TV show “is there a poison in
your mouth?” came out.
• 1991- Dental amalgam mercury syndrome groups started being
active.
• May 1991- Illinois house of representatives concluded amalgam
was safe.
• August 1991- national institute of health technology concluded
amalgam was safe.
13. WHAT ENDED THE WAR?
• Professional and consumer demand.
• In 1859, the leaders of the profession regrouped to form
the American Dental Association.
• Between 1860 and 1890, many experiments were done
to improve amalgam filling materials.
• It was the classical work of GV Black in 1895 that a
systemic study was done on properties & appropriate
manipulation of amalgam.
15. • During this Second Amalgam War, the American Dental
Association vigorously defended silver amalgam and its
widespread use was continued.
• Remarkably, the Food and Drug Administration (FDA) has
separately approved the mercury and the alloy powder for
dental use; but the amalgam mixture has never been
approved as a dental device
• Unfortunately now came the second world war over Europe
&" the second amalgam war" fell in forgetfulness
16. THIRD AMALGAM WAR
But it began primarily through seminars ,writings,&
videotapes of Dr HA Higgins, a dentist from Colorado
Springs
17. • Pressure from mounting clinical evidence forced the
ADA to finally publicly concede that mercury vapor does
escape from the amalgam filling into the patients mouth.
• But the ADA remained adamant that mercury in patients'
mouths is safe, and in 1986 it changed its code of
ethics, making it unethical for a dentist to recommend
the removal of amalgam because of mercury
• But problem flared in 1990’s by the telecast of television
program ‘60 minutes’ in CBC television
18. CURRENT STATUS ON AMALGAM WAR
• The amalgam war continues to rage on today.
• The problem is so serious that American Council on
Health & Science, has determined that allegations
against amalgam constitute one of the greatest
unfounded health scares of recent times
• There is presently a congressional bill in The United
States House of Representatives (H.R. 4163)
introduced by Rep. Diane Watson (D-CA) and Rep. Dan
Burton (R-IN) to ban the continued use dental amalgam
fillings.
19.
20.
21. • Norway banned dental amalgam in 2008
• Sweden banned the use of dental amalgam for almost all
purposes in 2009 and Denmark, Estonia, Finland, and Italy
use it for less than 5% of tooth restorations.
• Japan and Switzerland have also restricted or almost banned
dental amalgam.
• France has recommended that alternative mercury-free dental
materials be used for pregnant women.
22. • In December of 2016, three EU institutions (the European
Parliament, the European Commission and the Council of the
European Union) reached a provisional agreement to ban dental
amalgam fillings for children under 15 and pregnant and
breastfeeding women as of July 1, 2018, and to consider banning
dental amalgam completely by 2030.
• Safe Mercury Amalgam Removal Technique (SMART) should be
used when amalgam fillings are removed. SMART was developed
by IAOMT to mitigate mercury exposures that can occur when the
fillings are taken out of people’s mouths, which often occurs due
to hypersensitivity, and/or patient preference.
24. CLASSIFICATION BY MARZOUK
According to number of alloy metals:
• 1. Binary alloys (Silver-Tin)
• 2. Ternary alloys (Silver-Tin-Copper)
• 3. Quaternary alloys (Silver-Tin-Copper-Indium).
25. According to the shape of the powdered particles.
• 1. Spherical shape (smooth surfaced spheres).
• 2. Lathe cut (Irregular ranging from spindles to
shavings).
• 3. Combination of spherical and lathe cut (admixed).
26. According to Powder particle size.
• Micro cut
• Fine cut
• Coarse cut
According to copper content of powder
• Low copper content alloy - Less than 4%
• High copper content alloy - more than 10%
27. Based on zinc content-
• Zn containing (>0.01%)
• Zn free (<0.01%)
According to addition of Noble metals
• Platinum
• Gold
• Pallidum
28. According to compositional changes of succeeding generations
of amalgam
• First generation amalgam was that of G. V Black i.e. 3 parts silver one part
tin (peritectic alloy).
• Second generation amalgam alloys - 3 parts silver, 1 part tin, 4% copper to
decrease the plasticity and to increase the hardness and strength. 1 %
zinc, acts as a oxygen scavenger and to decrease the brittleness.
• Third generation: First generation + Spherical amalgam – copper eutectic
alloy.
• Fourth generation: Adding copper upto 29% to original silver and tin
powder to form ternary alloy. So that tin is bounded to copper.
• Fifth generation: Quatenary alloy i.e. Silver, tin, copper and indium.
• Sixth generation: consisting eutectic alloy which includes palladium, silver
and copper.
29. • Class I and class II cavities-moderate to large restorations.
• As a core build up material.
• Can be used for cuspal restorations (with pins usually)
• In combination with composite resins for cavities in posterior
teeth.
• As a die material
• Restorations that have heavy occlusal contacts.
INDICATIONS
30. • Class 3 in unaesthetic areas eg.distal aspect of canine.
especially if preparation is extensive with minimal facial
involvement
• Class 5 lesions in non-esthetic areas especially when
access is limited and moisture control is difficult and for
areas that are significantly deep gingivally.
• Restorations that cannot be well isolated.
• In teeth that act as an abutment for removable
appliances.
31. CONTRAINDICATIONS
• Anterior teeth where esthetics is a prime concern
• Esthetically prominent areas of posterior teeth.
• Small –to-moderate classes I and II restorations that
can be well isolated.
• Small class VI restorations
32. ADVANTAGES
• Ease of use, Easy to manipulate
• Relatively inexpensive
• Excellent wear resistance
• Restoration is completed within one sitting without
requiring much chair side time.
• Well condensed and triturated amalgam has good
compressive strength.
33. • Sealing ability improves with age by formation of
corrosion products at tooth amalgam interface.
• Relatively not technique sensitive.
• Bonded amalgams have “bonding benefits”.
Less microleakage
Slightly increased strength of remaining tooth
structure.
Minimal postoperative sensitivity.
34. DISADVANTAGES
• Unnatural appearance (non esthetic)
• Tarnish and corrosion
• Metallic taste and galvanic shock
• Discoloration of tooth structure
• Lack of chemical or mechanical adhesion to the tooth
structure.
• Mercury toxicity
• Promotes plaque adhesion
• Delayed expansion
• Weakens tooth structure (unless bonded).
37. • Copper (Cu)
ties up tin thereby reducing gamma-2 formation
increases strength
Increases setting expansion
reduces tarnish and corrosion
reduces creep, flow.
reduces marginal deterioration,
increases edge strength.
38. • Zinc (Zn)
provides better clinical performance
less marginal breakdown
decreases oxidation of other elements
Give plasticity, hastens setting , improves color of mass.
causes delayed expansion - both high & low Cu alloys if
contaminated with moisture.
39. • Indium (In)
decreases surface tension
reduces amount of mercury necessary
reduces emitted mercury vapor
reduces creep and marginal breakdown
increases strength
must be used in admixed alloys
41. • Mercury (Hg)
activates reaction
only pure metal that is liquid at room temperature
Spherical alloys
require less mercury
smaller surface area easier to wet
Admixed alloys
require more mercury
lathe-cut particles more difficult to wet
42.
43. MANUFACTURING PROCESS- LATHE CUT
Produced by cooling molten 72% Ag and 28%
Sn and forming an ingot (The ingot may be 3-4
cm in diameter and 20 -30 cm in length)
Alloy is heated for 8 hours at 400°C for
homogeneous distribution of silver and tin
Ingot is lathe-cut to produce the particles, ball
milled to reduce their size
The particles are 60-120µm in length, 10-70µm
in width & 10-35µm in thickness(Irregular in
shape)
44. PARTICLE TREATMENT
• Acid washed – Preferential dissolution of specific
components – acid washed powders more reactive than
unwashed powders
• Aging is basically a stress relief process.
• It makes the alloy stable in its reactivity and property for
indefinite period of time – improves shelf life.
• Generally done by heating them 60 to 100 ̊c for 1 to 6
hours
45. MANUFACTURING PROCESS- SPHERICAL
Produced by atomizing the molten alloy in a
chamber filled with an inert gas- argon
Molten metal falls through a distance of
approximately 30 feet and cools
Results in characteristic spherical particle
shapes.
If particles are allowed to cool before they contact the
surface of chamber, they are spherical in shape. If
they are allowed to cool on contact with the surface
they are flake shaped.
Particle size ranges form 5 to 40
microns
48. METALLURGICAL PROCESSES IN
AMALGAMATION- LOW COPPER ALLOYS
• Amalgamation occurs when mercury contacts the surface
of the silver-tin alloy particles.
• The silver and tin dissolve into the mercury.
• During the reaction, the formation of body centered
cubic form of Ag2Hg3 and hexagonal Sn7-8Hg occurs.
• Gamma 1 and 2 crystals grow as the remaining mercury
dissolves the alloy particles.
• As the mercury disappears, amalgam hardens.
49. • Alloy is mixed with mercury in the ratio of 1:1
• γ + Hg γ1 + γ2 + Unreacted alloy particles
γ1 - Dominant phase – 54-56%
Unreacted γ - 27- 35%
γ2- 11-13%
50. HIGH COPPER ALLOYS- ADMIXED
• 1963 innes and youdelis added silver copper eutectic alloy
particles ( 71.9% of Ag and 28.1% Cu) to lathe cut low
copper alloys.
• Also called as blended alloys.
• Contain 2 parts by weight of conventional composition lathe
cut particles plus one part by weight of spheres of a silver
copper eutectic alloy.
• The silver tin particle is usually formed by the lathe cut
method, whereas the silver copper particle is usually
spherical in shape
• The AgCu particles acts as strong fillers in strengthening the
amalgam matrix.
• copper content - 9 to 20%.
51. • The mercury dissolved in the Ag-Sn particles forms gamma 1 and
2 phases leaving some unreacted Ag-Sn particles.
• The newly formed gamma 2 around the Ag-Sn particles reacts with
AgCu eutectic alloy particles and forms the η phase (Cu6Sn5)
along with some gamma 1 phase around Ag-Cu particles.
• Ag3Sn + Ag-Cu + Hg Ag3Sn + Ag2Hg3 + Sn8Hg + Ag-Cu
• Sn8Hg + Ag-Cu Cu6Sn5 + Ag2Hg3 + Ag-Cu
52. UNICOMPOSITIONAL ALLOY
• It is so called as it contains particles of same composition
(Asgar – 1974)
• Usually Spherical in nature
• Cu Content 13 – 30 %.
• The particles of unicompositional alloys in very early stages
of setting are surrounded by gamma 1 and 2 phases and the
periphery becomes an alloy of Ag and Cu.
• Gamma 2 reacts with Ag-Cu phase and forms η and more
gamma 1.
54. PROPERTIES
ADA specification No.1 for amalgam lists following
physical properties as a measure of quality of the
amalgam.
• Creep
• Strength
• Dimensional changes
• Modulus of elasticity
55. 1) STRENGTH
A) COMPRESSIVE STRENGTH
• Amalgam is strongest in compression & much weaker in
tension & shear.
• When subject to a rapid application of stress either in tension
or compression a dental amalgam does not exhibit significant
deformation or elongation & as a result functions as a brittle
material
• High copper single composition materials have the highest
early compressive strength of more than 250 Mpa at 1 hr
• While it is lowest for the low copper lathe cut alloy(145 Mpa)
56. • High values for early compressive strength are advantage for
an amalgam, because they reduce the possibility of fracture by
application of prematurely high occlusal forces by the patient
before the final strength is reached
• The compressive strength at 7 days is again highest for the
high copper single composition alloys, with only modest
differences in the other alloys.
• Tooth preparation should be done in such a way that they are
subjected to more of compressive stresses and less of tensile
stresses.
• The compressive strength of a satisfactory amalgam restoration
should be atleast 310 MPa
58. B) TENSILE STRENGTH
• Amalgam is much weaker in tension
• Tensile strengths of amalgam are only a fraction of their
compressive strengths
• Cavity design should be constructed to reduce tensile
stresses resulting from biting forces
• High early tensile strengths are important – resist fracture by
prematurely applied biting forces
• Both low & high copper amalgams have tensile strength that
range between 48-70 MPa
60. FACTORS AFFECTING STRENGTH
A) Effect of Trituration:
• Effect of trituration on strength depends on the type of
amalgam alloy, the trituration time and the speed of the
amalgamator.
• Under trituration or over-trituration decreases the strength for
both traditional and high copper amalgams.
• More the trituration energy used, more evenly distributed are
the matrix crystals over the amalgam mix and consequently
more the strength pattern in the restoration.
• Excess trituration after formation of matrix crystals will create
cracks in the crystals, and lead to drop in strength of set
amalgam
61. • B) Effect of Mercury
• Sufficient mercury should be there to coat the particles.
• Low mercury alloy content, contain stronger alloy particles
and less of the weaker matrix phase, therefore there is more
strength.
• If mercury is too less it leads to a dry, granular mix, which
results in a rough, pitted surface that invites corrosion.
• If the mercury content increases beyond 54% the strength
reduces markedly
62. C) Effect of condensation
• For lathe cut amalgam, greater the condensation pressure
higher the compressive strength. Higher condensation
pressure is required to minimize porosity and to express
mercury.
• Spherical amalgam - light condensation pressure produces
adequate strength.
63. D) Effect of porosity
• Voids & porosities reduces strength
• Porosity is caused by:
a. Decreased plasticity of the mix (due to low Hg/alloy ratio,
delayed condensation, under-trituration)
b. Inadequate condensation pressure (results in inappropriate
adaptation at the margins & increase number of voids)
c. Irregularly shaped particles of alloy powder
d. Insertion of too large increments
64. E) Temperature:
• Amalgam looses 15% of its strength when its temperature
is elevated from room temperature to mouth temperature
• It looses 50% of room temperature strength when
temperature is elevated to 60 deg C e.g. hot coffee or
soup.
65. 2) CREEP AND FLOW
• Creep is Defined as time dependent strain or deformation
produced by stress (as in Phillips)
• Creep of dental amalgam is a slow progressive permanent
deformation of set amalgam which occurs under constant
stress (static creep) or intermittent stress (dynamic creep)
• Creep is related to marginal breakdown of low copper
amalgams
• Higher the creep, the greater is the degree of marginal
deterioration (ditching)
• It is measured after the amalgam has set.
66. • According to ADA sp. No.1 creep should be below 3%
• Creep values:
Low copper amalgam:0.8-8%
High copper amalgam:0.1-1%
• Creep rate has been found to correlate with marginal
breakdown of conventional low-copper amalgams.
• High-copper amalgams have creep resistance because of lack
of gamma-2 phase.
FLOW:
Flow refers to the deformation that occurs during the setting of
amalgam.
Greater the flow, greater are chances for restoration failure.
67. FACTORS INFLUENCING CREEP
A) Phases of amalgam restorations
• Creep rate decreases with larger gamma1 grain sizes.
• Gamma 2 is associated with high creep rates.
• In absence of gamma 2, low creep rates in single
composition alloy may be due to eta phase which act as
barrier to deformation of gamma1 phase.
68. B) Manipulations:
• Greater compressive strength will minimize creep rates.
• Low mercury: alloy ratio, greater the condensation
pressure and time of trituration, will decrease the creep
rate.
69. 3) DIMENSIONAL CHANGE
• Severe contraction leads to plaque accumulation &
secondary caries
• Expansion leads to postoperative pain & splitting of tooth
• If amalgam expanded during hardening, leakage around the
margins of restorations would be eliminated.
• Largest dimensional change -19.7µg/cm- low cu lathe cut
alloy.
• Lowest -1.9µm/cm – high cu admixed alloy.
70. • Evidently the detrimental effect of shrinkage occurs only
when the amalgam mass shrinks > 50 µm.
• According to ADA/ANSA SPECIFICATION NO-1.
+-20µm/Cm is allowed.
71. When mercury is combined with amalgam it undergoes three
distinct dimensional changes:
• Stage -1: Initial contraction, occurs for about 20 minutes
after beginning of trituration. Contraction results as the alloy
particles dissolve in mercury. Contraction, which occurs, is
no greater than 4.5 µcm.
• Stage -2: Expansion- this occurs due to formation and
growth of the crystal matrix around the unconsumed alloy
particles.
• Stage -3: Limited delayed contraction.
72. FACTORS THAT AFFECT THE DIMENSIONAL
CHANGES:
1) Particle size and shape:
• More regular the particle shape, more smoother the
surface area.
• Faster and more effectively the mercury can wet the
powder particles and faster amalgamation occurs in all
stages with no apparent expansion.
73. 2) Mercury:
• More mercury , more will be the expansion, as more crystals
will grow.
• Low mercury: alloy ratio favors contraction.
3) Manipulation:
• During trituration, if more energy is used for manipulation,
the smaller the particles will become , mercury will be
pushed between the particles, discouraging expansion.
• More the condensation pressure used during condensation,
closer the particles are brought together; more mercury is
expressed out of mix inducing more contraction.
74. CONTRACTION
Alloys dissolve in mercury and becomes smaller in size.
FACTORS FAVOURING CONTRACTION
• Less mercury content
• Higher condensation pressure
• Over trituration
• Smaller particle size
• Spherical alloys have more contraction
• Low Hg - higher contraction.
75. EXPANSION:
• 16.6% of restorations fail- expansion.
• The impingement of growing crystals one on another will cause
outward forces which will result in some expansion (crystal
growth pressure)
• If sufficient Hg is present to produce a plastic matrix, expansion
occurs as a result of growth of ƴ1 crystals & viceversa
• According U.S Bureau of standards a dimensional change on
setting, value of 5 - 10µm allowable.
76. DELAYED EXPANSION
• Dr Grey - 1920
• Takes place after 24 hours. Zinc containing amalgam when
contaminated with moisture during trituration or condensation
can result in delayed expansion.
• This expansion can be for 3-5 days to months reaching values
greater than 400µm • Also called as secondary expansion.
• Hydrogen is produced by the electrolytic action involving zinc
and water which does not combine in amalgam but rather
collects within the restoration increasing the internal pressure
causing amalgam to expand.
Zn + H2O ZnO + H2
77. COMPLICATIONS THAT MAY RESULT DUE TO
DELAYED EXPANSION ARE:
• Protrusion of the entire restoration out of the cavity.
• Increased micro leakage space around the restoration.
• Restoration perforations.
• Increased flow and creep.
• Pulpal pressure pain.
Such pain may be experienced 10-12 days after the insertion of
the restoration
78. 4) TARNISH AND CORROSSION
• Tarnish – surface discolouration on a metallic surface
without the loss of structure. ( sulphide layer)
• It depends on oral environment and type of alloy.
• In case of low copper alloys, gamma phase is responsible.
For high copper alloys, eta and Ag-Cu eutectic are
responsible.
• Does not cause any detrimental effect on the amalgam
79. CORROSION
• Corrosion – actual deterioration of metal by reaction with its
environment.
• Porosity,
• Reduced marginal integrity and
• Loss of strength
• Tin oxychloride is the corrosion product formed. (low copper)
Sn7-8Hg + 1/202 + H2O + Cl- -> Sn4 (OH)6 Cl2 + Hg
• Corrosion product CuCl2.3Cu(OH)2 (high copper)
Cu6Sn5 + 1/202 +H2O + Cl- -> CuCl2.3Cu (OH)2 + SnO.
80. GALVANIC CORROSION:
• If dental amalgam is in direct contact with an adjacent metallic
restoration such as gold crown galvanic corrosion takes place. The
dental amalgam is the anode in the circuit. Saliva being the electrolyte.
STRESS CORROSION:
• Regions that are under stress display a greater probability for corrosion,
thus resulting in stress corrosion. For occlusal dental amalgam greatest
combination of stress and corrosion occurs along the margins.
CREVICE CORROSION:
• Local electrochemical cells may arise whenever a portion of amalgam is
covered by plaque on soft tissue. It behaves anodically and corrodes. If
these occur in cracks or crevice, it is called crevice corrosion.
81.
82. Electro chemical studies show
• γ1 phase has the highest corrosive resistance followed by γ,
AgCu, ε and η
• Least resistant to corrosion is the γ2 phase.
• γ2 phase crystals are long and blade like, penetrating throughout
the matrix. They form a penetrating matrix because of the
intercrystalline contact between the blades. Hence this phase is
more prone for corrosion producing penetrating corrosion.
• γ2 is more electronegative than γ and γ1 phases. So this induces
galvanic corrosion.
83. • Corrosion products from the tin in gamma 2 phase include tin
oxychloride. Due to corrosion, mercury gets released.
• This mercury then reacts with unreacted gamma particles and
produces additional gamma 1 and 2 phases which results in
some expansion called as MERCUROSCOPIC EXPANSION.
This results in porosity and reduction in strength.
• Corrosion on surface of amalgam restorations usually occurs
to a depth of about 100 – 500 micrometers.
• Phosphate buffering ability of saliva is known to inhibit this
process and provide protection against corrosion.
84. FACTORS RELATED TO EXCESS TARNISH &
CORROSION
• High residual mercury
• Contact of dissimilar metals, eg. gold & amalgam
• Surface texture- scratches and voids
• Moisture contamination during condensation
• Type of alloy-low cu alloy>high cu alloy
85. CORROSION CAN BE REDUCED BY:
• Smoothening & polishing the restoration
• Correct mercury/alloy ratio & proper
manipulation
• Avoid dissimilar metals including mixing of
high & low copper amalgams
86. SELF SEALING ABILITY OF AMALGAM
• Though corrosion and corrosion products are detrimental
to a restoration, it is advantageous in amalgam
restorations.
• Since amalgam doesn’t bond to the tooth, the corrosion
products seal the amalgam and tooth interference.
• This is seen more in low copper amalgam than high
copper amalgam.
88. RESIN COATED AMALGAM
• To overcome the limitation of microleakage with
amalgams, a coating of unfilled resin over the restoration
margins and the adjacent enamel, after etching the
enamel, has been tried.
• Although the resin may eventually wear away, it delays
microleakage until corrosion products begin to fill the tooth
restoration interface.
89. FLUORIDATED AMALGAM
• Fluoride, being cariostatic, has been included in amalgam to deal with
the problem of recurrent caries associated with amalgam restorations.
It was proposed by Innes and Youdelis in 1966, Serman in 1970 and
Stone in 1971
• Several studies concluded that a fluoride containing amalgam may
release fluoride for several weeks after insertion of the material in
mouth.
• the fluoride release from this amalgam seems to be considerable during
the first week.
90. • An anticariogenic action of fluoride amalgam could be explained by
its ability to deposit fluoride in the hard tissues around the fillings and
to increase the fluoride content of saliva, subsequently affecting
remineralization.
• In this way, fluoride from amalgam could have a favorable effect not
only on caries around the filling but on any initial enamel
demineralization.
• The fluoride amalgam thus serves as a “slow release device”
• Example: Fluoralloy
• The problem with this method is that the fluoride is not delivered long
enough to provide maximum benefit.
Fluoride release from a fluoride-containing amalgam in vivo. Skartveit L, Tveit AB, Ekstrand J Scand J Dent
Res. 1985 Oct; 93(5):448-52.
91. BONDED AMALGAM
• Since amalgam does not bond to tooth structure, microleakage
immediately after insertion is inevitable.
• So, to overcome these disadvantages of amalgam, adhesive systems
that reliably bond to enamel and dentin have been introduced.
• Amalgam bond is based on a dentinal bonding system developed in
Japan by Nakabayashi and co-workers.
• 4META has been used to bond amalgam to cavity walls.
• The bond strength in admixed alloys was lower than those achieved
with spherical alloys.
92. • One study compared post-insertion sensitivity of teeth with
bonded amalgams to that of teeth with pin-retained amalgams.
After 6 months, teeth with bonded amalgams were less sensitive
than teeth with pin-retained amalgams.
• This difference in sensitivity was not present 1 year after insertion.
This is possibly because of corrosion products in nonbonded
amalgam restorations filling the interface, and thus, decreasing
microleakage and sensitivity.
Summitt JB, Burgess JO, Osborne JW, Berry TG, Robbins JW. Two year evaluation of amalgambond plus
and pin-retained amalgam restorations (abstract 1529) J Dent Res. 1998;77:297.
93.
94. GLASS CERMET
• It is also called as cermet ionomer cements. McLen and
Gasser in 1985 first developed this material. Fusing the
glass powder to silver particles through sintering that can be
made to react with polyacid to form the cement.
• The properties include strength which is both tensile and
compressive strength is greater than conventional glass
ionomer cement. The abrasion resistance is greater than
conventional GIC due to silver particle incorporation.
• The silver cement radiopacity is equal to that of dental
amalgam. The fluoride release for cermet is about 3350
ug in 2 weeks and about 4040 ug in 1 month.
95. GALLIUM – AN ALTERNATIVE TO AMALGAM
• As early as 1956, Smith and Caul and Smith and co-workers
claimed that a gallium based alloy could serve as a possible
alternative to dental amalgam.
• They found that mixing gallium with either nickel or copper and
tin produced a pliable mass that could be condensed into a
prepared cavity, which, after setting, had physical properties
suitable for a restorative material.
• Commercial brands are: Galloy, Bayswater,
Gallium GF, Gallium GF II
98. INDIUM CONTAINING ALLOY POWDER AND
MERCURY-INDIUM LIQUID ALLOY
• Powell et al in 1989 added pure indium powder with high
copper alloy and triturated it with mercury.
• A significant decrease in mercury evaporation was seen.
• This was marked as : Indisperse and Indiloy
• Youdelis found that less mercury is required for mixing
amalgam when 10% Indium is present.
• Johnson GH et al : indium containing
high copper alloy exhibited low creep
and increase in strength.
99.
100. CONSOLIDATED SILVER ALLOY SYSTEM
• One amalgam substitute being tested is a consolidated silver alloy system
developed at the National Institute of Standards and Technology.
• It uses a fluoroboric acid solution to keep the surface of the silver alloy
particles clean. The alloy, in a spherical form, is condensed into a
prepared cavity in a manner similar to that for placing compacted gold.
• One problem associated with the insertion of this material is that the alloy
strain hardens, so it is difficult to compact it adequately to eliminate
internal voids and to achieve good adaptation to the cavity without using
excessive force.
Bharti R, Wadhwani KK, Tikku AP, Chandra A. Dental amalgam: An update. Journal of conservative
dentistry: JCD. 2010 Oct;13(4):204.
101. MERCURY FREE AMALGAM
• Here, an experimentation was done which involved discarding the
mercury content of amalgam and replacing it with a proprietary
antimicrobial silver solution and unsialinized titanium dioxide ceramic
nanoparticles for strength, with a favorable, easy to manipulate
consistency.
• Prepared maxillary premolar controls were filled with Permite amalgam
and compared to an experimental group filled with the novel material.
102. • Both groups were then thermocycled, cross-sectioned, and
studied through scanning electron microscopy (SEM).
• It was concluded that the addition of the silver solution and
ceramic nanoparticles to mercury-free regular-set Permite alloy
yielded a product that exhibits improved marginal adaptation with
less application of condensation pressure, when compared to
regular-set Permite amalgam.
103. CONTROVERSIES IN AMALGAM
Basun et al. (1991) and Hock et al.
(1998) demonstrated a significant
nearly twofold increase in plasma
and blood Hg levels in AD
patients when compared to the
respective values from age matched
controls.
Ehmann et al. (1986) found higher levels of Hg in the brain of
autopsied AD patients than the control subjects without AD.
104. CONTROVERSIES IN AMALGAM
Mackert and Berglund
concluded that the extremely
low dosage of mercury
attributable to amalgam
restorations
was insufficient to produce any
detectable negative effect on
general health.
Data strongly suggest
that mercury levels
many times higher
than those associated
with a mouth full of
amalgam pose no
risk of adverse
health effects.
Ekstrand and colleagues found no effects on
various parameters of kidney function in humans
105. CONCLUSION:
• Dental amalgam has served as an excellent and versatile
restorative material for many years, despite periods of
controversy.
• It has served as a dental restoration for more than 165 years.
There is still no adequate economic alternative for dental
amalgam.
• Although there is evidence of a decrease in its use in the world,
amalgam’s cost, durability and ease of manipulation have
persuaded many dentists to continue to use it as their first choice
for restoring posterior teeth.
106.
107.
108.
109. • Also, in regards to dental allergies, Dr. Stejskal introduced the
MELISA test in 1994. This is a modified version of the Lymphocyte
Transformation Test designed to test for metal sensitivity type IV
delayed hypersensitivity to metals, including sensitivity to mercury.
• Amalgam will probably disappear eventually, but its
disappearance will be brought about by a better and more esthetic
material, rather than by concerns over health hazards.
• When it does disappear, it will have served dentistry and patients
well for more than 200 years.
110. REFERENCES
• J Conserv Dent. 2010 Oct;13(4):204-8. Dental amalgam: An update
• The amalgam controversy-an evidence based analysis ; JADA,Vol.132,march 2001
• Mertz-Fairhurst EJ, Curtis JW, Jr, Ergle JW, Rueggeberg RA, Adair SM. Ultraconservative
and cariostatic sealed restorations: Results at year 10. J Am Dent Assoc. 1998;129:55–
66.
• Summitt JB, Burgess JO, Osborne JW, Berry TG, Robbins JW. Two year evaluation of
amalgambond plus and pin-retained amalgam restorations (abstract 1529) J Dent Res.
1998;77:297.
• Bharti R, Wadhwani KK, Tikku AP, Chandra A. Dental amalgam: An update. Journal of
conservative dentistry: JCD. 2010 Oct;13(4):204.
• DODES, J. E. (2001). The amalgam controversy. The Journal of the American Dental
Association, 132(3), 348–356. doi:10.14219/jada.archive.2001.0178
• PHILLIPS’ Science of Dental Materials;11th ed Kenneth J. Anusavice
• CRAIG’s Restorative Dental Materials;12th ed John M. Powers, Ronald L. Sakaguchi
Dental amalgam is one of the oldest materials used in dentistry, despite all its controversis, it is still being used in a lot of clinics especially in inida. As an economic and durable replacemnt has not been found yet
Dental rubber dam, saliva ejector, high volume evacuation, remove the amalgam in large chunks by sectioning, face sheilds by dentists etc
LATHE CUT CAN BE CONDESNSED AND REQUIRES MORE MERCURY
Bcz the solubility of sil in merc is much lower thn that of tin, the gam1 precipitates first and gam 2 precipitates later.
Second phase happens at mouth temp for 1-2 weeks
Eta and gam 1 form around unrracted alloy. Protects .
reduces creep
prevents gamma-2 formation
fortunately, voids are not the problem with spherical alloy.
Tooth has darkened as corrosion products from the amalgam have formed.
PHOS BUFFER OF SALIVA AND ETA PHASE CAUSE CORROSION RESISENCE
12- 15 Mpa low. 27 mpa
Gallium is liquid at room temp.
Tytin- spherical silver amalgam (brand name)
Also cost is high, very sticky and more corrosion prone
Data were retrieved from the Longitudinal Health Insurance Database (LHID 2005 and 2010). Alzheimer’s disease was diagnosed using the International Classification of Diseases, Women who were exposed to amalgam fillings were 1.132 times more likely to have Alzheimer’s disease than were their non-exposed counterparts.
Mercury from dental amalgam restorations cannot be linked to kidney damage, Alzheimer's disease, multiple sclerosis, other central nervous system diseases, "amalgam disease." mental disorders, damage to the immune system, increases in antibiotic resistance, or harmful reproductive effects. Dentists occupationally exposed to mercury have not been shown to suffer harmful reproductive or other systemic health effects, provided proper mercury hygiene is used.
2) Saxe and colleagues’ study,53 in particular, was compelling because the participants were RomanCatholic nuns who were 75 to 102 years old. SHOWED no LESS COGNITION THAN WITHOUT AMALGAM
Mst common was resin . But failed within 4 years , amal – 12 yrs
Strength and longevity of resins are comparable to composotes.