This document discusses prosthetic resin polymers used in dentistry. It provides an overview of their various uses including denture bases, denture teeth, relining materials, and more. It describes the functions of denture base materials in distributing pressure and retaining teeth. The document outlines different types of resin polymers like heat cured acrylic, chemically cured acrylic, and light cured acrylic. It discusses considerations for manipulating resin polymers, such as controlling processing strains from shrinkage.
This document discusses adhesion and bonding in dentistry. It begins by introducing the fundamental objective of creating adhesion between tooth structure and restorative materials. It then covers the principles of adhesion, including the different types of adhesion mechanisms. Some key factors and challenges that impact adhesion are surface energy, contact angle, wetting, surface contamination, and water content. The document reviews the history of bonding agents, from early experiments in the 1950s to the development of multi-step bonding systems. It also separates the discussion of enamel bonding agents from dentin bonding agents.
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
This document discusses different types of all-ceramic dental restorations, including their compositions and manufacturing techniques. It describes sintered ceramics like alumina and leucite-based materials, heat pressed ceramics like IPS Empress and lithium disilicate, slip cast ceramics like In-Ceram alumina and spinel, and machinable ceramics milled using CAD/CAM or copy milling. The advantages of all-ceramic restorations are also summarized, such as superior esthetics, biocompatibility, and bond strength compared to ceramic-metal restorations.
This document discusses denture base resins. It provides a brief history of denture materials from ancient Egypt to modern times. Key definitions are provided, including classifications of denture base resins. Ideal requirements and properties of denture base materials are outlined. Stages of polymerization and manipulation of the resins are described. Recent advancements and a literature review are mentioned.
Dental polymers with recent advancements in dental base techniques 2PoojaKhandelwal45
This document discusses recent advancements in dental polymers and base techniques. It begins with definitions of polymers and polymerization. The history of dental polymers is then reviewed, including the development of synthetic elastomers in the 20th century and the introduction of PMMA and resin-based composites. Various dental applications of polymers are listed. Key aspects of polymers like chain length, branching, copolymer structures, and properties are described. The document concludes with an overview of addition and step-growth polymerization, as well as details on acrylic dental resins.
The document discusses various principles of adhesion in dentistry. It describes the different mechanisms of adhesion including mechanical adhesion, adsorption adhesion, diffusion adhesion, and electrostatic adhesion. It also outlines the requirements for good adhesion such as sufficient wetting of the adhesive, low viscosity, rough surface texture of the adherend, and high surface energy of the adherend. Additionally, it explains factors that affect adhesion to tooth structures like the smear layer and differences between adhesion to enamel versus dentin.
Resin based composites(Recent Advances)Taduri Vivek
This document provides an overview of dental composites, including their history, classification, composition, properties, and recent developments. It discusses the key components of composites such as the resin matrix, fillers, coupling agents, and photoinitiators. It also summarizes the different types of composites based on particle size, polymerization method, and other characteristics. Recent innovations in composites include antibacterial, flowable, packable, compomers, and fiber-reinforced formulations.
This document discusses adhesion and bonding in dentistry. It begins by introducing the fundamental objective of creating adhesion between tooth structure and restorative materials. It then covers the principles of adhesion, including the different types of adhesion mechanisms. Some key factors and challenges that impact adhesion are surface energy, contact angle, wetting, surface contamination, and water content. The document reviews the history of bonding agents, from early experiments in the 1950s to the development of multi-step bonding systems. It also separates the discussion of enamel bonding agents from dentin bonding agents.
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
This document discusses different types of all-ceramic dental restorations, including their compositions and manufacturing techniques. It describes sintered ceramics like alumina and leucite-based materials, heat pressed ceramics like IPS Empress and lithium disilicate, slip cast ceramics like In-Ceram alumina and spinel, and machinable ceramics milled using CAD/CAM or copy milling. The advantages of all-ceramic restorations are also summarized, such as superior esthetics, biocompatibility, and bond strength compared to ceramic-metal restorations.
This document discusses denture base resins. It provides a brief history of denture materials from ancient Egypt to modern times. Key definitions are provided, including classifications of denture base resins. Ideal requirements and properties of denture base materials are outlined. Stages of polymerization and manipulation of the resins are described. Recent advancements and a literature review are mentioned.
Dental polymers with recent advancements in dental base techniques 2PoojaKhandelwal45
This document discusses recent advancements in dental polymers and base techniques. It begins with definitions of polymers and polymerization. The history of dental polymers is then reviewed, including the development of synthetic elastomers in the 20th century and the introduction of PMMA and resin-based composites. Various dental applications of polymers are listed. Key aspects of polymers like chain length, branching, copolymer structures, and properties are described. The document concludes with an overview of addition and step-growth polymerization, as well as details on acrylic dental resins.
The document discusses various principles of adhesion in dentistry. It describes the different mechanisms of adhesion including mechanical adhesion, adsorption adhesion, diffusion adhesion, and electrostatic adhesion. It also outlines the requirements for good adhesion such as sufficient wetting of the adhesive, low viscosity, rough surface texture of the adherend, and high surface energy of the adherend. Additionally, it explains factors that affect adhesion to tooth structures like the smear layer and differences between adhesion to enamel versus dentin.
Resin based composites(Recent Advances)Taduri Vivek
This document provides an overview of dental composites, including their history, classification, composition, properties, and recent developments. It discusses the key components of composites such as the resin matrix, fillers, coupling agents, and photoinitiators. It also summarizes the different types of composites based on particle size, polymerization method, and other characteristics. Recent innovations in composites include antibacterial, flowable, packable, compomers, and fiber-reinforced formulations.
brief description about pressable ceramicsCONTENTS: • Introduction • Definition For Dental Ceramics • Definition For Pressable Ceramics • History • Various All Ceramic Systems • Classification • Pressable Ceramics • History • Generation Of Pressable Ceramics • Cerestore – Development Fabrication Advantage Disadvantage 2
3. IPS Empress - Materials And Composition Special Furnace Fabrication Advantage Disadvantage IPS Empress 2- INDICATION Properties Fabrication Method Advantage Disadvantage IPS Emax Press - Microstructure Composition Properties OPC 3G- Development Indication Properties 3
4. INTRODUCTION There have been significant TECHNOLOGICAL advances in the field of dental ceramics over the last 10 years which have made a corresponding increase in the number of materials available. Improvements in strength, clinical performance, and longevity have made all ceramic restorations more popular and more predictable 4
5. DEFINITION FOR DENTAL CERAMICS⁶ An inorganic compound with non metallic properties typically consisting of oxygen and one or more metallic or semi metallic elements (e.g ;Aluminium, Calcium, Lithium, Mangnesium, Potassium, Sodium, Silicon, Tin , Titanium And Zirconium)that is formulated to produce the whole or part of a ceramic based dental prosthesis 5
6. DEFINITION FOR PRESSABLE CERAMICS ⁶ • A ceramic that can be heated to a specified temperature and forced under pressure to fill a cavity in a refractory mold 6
7. HISTORY OF DENTAL CERAMICS ⁶ • 1789-first porcelain tooth material by a French dentist De Chemant • 1774- mineral paste teeth by Duchateau in England • 1808-terrometallic porcelain teeth by Italian dentist Fonzi • 1817- Planteu introduced porcelain teeth in US • 1837- Ash developed improved version of porcelain teeth 7
8. • 1903 – Dr.Charless introduced ceramic crowns in dentistry he fabricate ceramic crown using platinum foil matrix and high fusing feldspathic porcelain excellent esthetics but low flexural strength resulted in failure • 1965- dental aluminous core Porcelain by Mclean and Huges • 1984- Dicor by Adair and Grossman 8
9. 9
10. VARIOUS ALL CERAMIC SYSTEMS Aluminous core ceramics Slip cast ceramics Heat pressed ceramics Machined ceramics Machined and sintered ceramics Metal reinforced system 10
11. MICROSTRUCTURAL CLASSIFICATION⁵ Category 1: Glass-based systems (mainly silica) Category 2: Glass-based systems (mainly silica) with fillers usually crystalline (typically leucite or a different high-fusing glass) a) Low-to-moderate leucite-
Recent advances have improved dental composite materials. Composites contain resin and inorganic fillers to increase strength while decreasing problems from resin such as shrinkage. Larger filler particles improve strength but smoothness while smaller fillers enhance esthetics. Novel composites aim to reduce shrinkage through techniques like silorane resin which uses a different polymerization or bulk fill which can be placed in 4mm layers. Other trends include nano-filled composites with ultra-small particles achieving high filler loading and strength, and smart composites which release ions to prevent decay. Indirect composites can be contoured outside the mouth but still experience shrinkage during cementation. Overall composites continue advancing but shrinkage remains a challenge.
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.for more details please visit
www.indiandentalacademy.com
This document provides an overview of denture base materials. It discusses the definition of a denture base and ideal properties. Denture base materials are classified as metallic or non-metallic. A history of materials used from the 18th century to present is provided, including vulcanite, acrylic resin, and newer polymers. Types of denture base polymers are described, including heat-cured acrylic resin, auto-polymerizing acrylic, and alternatives like fiber-reinforced polymers. Methods of polymerization and various commercial brands are also summarized.
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
This document discusses dental casting investments, which are materials used to form molds for casting dental restorations like crowns and bridges. It describes the components of investments, including refractory materials like silica, binders like gypsum or phosphate, and modifiers. It explains the properties investments must have like strength, expansion to compensate for shrinkage, and smooth surfaces. It covers the different types of investments including gypsum-bonded, phosphate-bonded, and silica-bonded and their appropriate uses and temperature ranges. It also discusses factors that affect the investments' setting expansion to help compensate for casting shrinkage.
This document discusses finishing and polishing of restorative materials in dentistry. It defines finishing as removing surface defects from contouring, and polishing as providing luster to a surface. Finishing and polishing are important for oral health, function, and aesthetics as they reduce plaque accumulation, staining, and irritation. The document outlines the principles, mechanisms, instruments, and procedures for cutting, grinding, finishing and polishing restorative surfaces. It also reviews different types of abrasives and their uses.
Calcium hydroxide cements were introduced by Hermann in 1920 as an alternative to viewing exposed pulps as "doomed organs." Calcium hydroxide cements promote healing in clinical situations by creating an alkaline environment. They are formed through a reaction of calcium oxide with water to create calcium hydroxide. Typical calcium hydroxide cements are composed of calcium hydroxide, zinc oxide, zinc stearate, and ethyl toluene sulphonamide. They set through exothermic chemical reactions, have biocompatibility that can destroy bacteria and initiate reparative dentin formation, but have low strength and solubility in moisture.
1. Etchant acid, also known as phosphoric acid, is used to condition tooth enamel prior to placing restorative materials like resins, sealants, and adhesive cements. It demineralizes the enamel, creating micro pores to achieve a strong bond between the material and tooth.
2. The acid is applied for 15-60 seconds and then rinsed thoroughly before the restorative material is placed. This micro-etching of the enamel improves retention of the restoration.
3. For ceramics, hydrofluoric acid is used which also etches the material by creating channels, allowing chemical bonding between the ceramic, silane, and resin for strong adhesion.
Indirect restorations are fabricated outside of the mouth using laboratory processed composites or ceramics. They are indicated for large defects or esthetic areas and provide better physical properties than direct composites. However, they have increased costs and time. Tooth preparation for indirect restorations requires rounded line angles, occlusal convergence, and extension to sound tooth structure. Impressions are needed to fabricate the restoration on a working cast.
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 discusses dentin bonding agents. It provides background on adhesion and the challenges of bonding to dentin compared to enamel. Key points discussed include:
- Conditioning of dentin is needed to remove the smear layer and expose collagen fibers. This can be done chemically using acids or chelators.
- Primers are then used which contain both hydrophilic and hydrophobic monomers. They displace water from the moist collagen network and allow resin infiltration.
- The concept of "wet bonding" was introduced, in which acid-etched dentin is kept moist during bonding to maintain the expanded collagen network for resin penetration.
The document discusses various die materials and systems used for indirect restorations. It defines a die as a positive reproduction of a prepared tooth used to fabricate restorations outside the mouth. Common die materials include gypsum, resins, metals and polymers, each with advantages and disadvantages. Removable die systems like dowel pins, Di-Lok and Pindex are discussed which allow repositioning of dies in the working cast for wax pattern fabrication. Proper selection of die material and system depends on factors like accuracy, strength and compatibility with impression materials.
Composite Resin Luting cements (2nd edition) presentation powerpoint
A type of dental cement
Used for cementation of indirect restorations & brackets
A summary of five textbooks
The document provides an overview of base metal alloys used in dentistry. It discusses the history and classification of dental casting alloys including cobalt-chromium, nickel-chromium, and titanium-based alloys. The ideal requirements, composition, properties, applications and references of various base metal alloys are described in detail over multiple pages.
The document discusses various materials used in maxillofacial prosthetics. It describes ideal materials as being biocompatible, flexible, colorable, chemically stable, easy to process, and strong. Room temperature vulcanizing materials and modeling materials like clay, plaster, and wax are introduced. The fabrication phase uses extraoral materials like acrylics, vinyl polymers, and elastomers like polyurethane and silicone, which are considered most desirable due to their strength. High temperature vulcanizing silicone provides good strength and detail but requires specialized equipment for processing.
This document discusses dental porcelain, including its composition, manufacturing process, strengthening methods, and applications in ceramic and metal-ceramic restorations. Dental porcelain is a type of ceramic composed of kaolin, silica, and feldspar that is fired at high temperatures. It is used for ceramic crowns, veneers, and metal-ceramic restorations due to its biocompatibility, esthetics, and thermal properties matching enamel and dentin. However, porcelain is also brittle with low tensile strength, so various strengthening techniques are used. Metal-ceramic restorations bond porcelain to metal frameworks, requiring thermal and chemical compatibility between the materials.
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.
This document discusses various types of additives used in polymer processing and their functions. It describes additives like stabilizers, lubricants, plasticizers, fillers, fibers, coupling agents, antistatic agents, slip agents, anti-block agents, nucleating agents, optical brighteners, colorants, anti-aging additives, impact modifiers, flame retardants, blowing agents, and master batches. It provides examples and explains how each additive type alters polymer properties or facilitates processing to achieve the desired characteristics in final products.
brief description about pressable ceramicsCONTENTS: • Introduction • Definition For Dental Ceramics • Definition For Pressable Ceramics • History • Various All Ceramic Systems • Classification • Pressable Ceramics • History • Generation Of Pressable Ceramics • Cerestore – Development Fabrication Advantage Disadvantage 2
3. IPS Empress - Materials And Composition Special Furnace Fabrication Advantage Disadvantage IPS Empress 2- INDICATION Properties Fabrication Method Advantage Disadvantage IPS Emax Press - Microstructure Composition Properties OPC 3G- Development Indication Properties 3
4. INTRODUCTION There have been significant TECHNOLOGICAL advances in the field of dental ceramics over the last 10 years which have made a corresponding increase in the number of materials available. Improvements in strength, clinical performance, and longevity have made all ceramic restorations more popular and more predictable 4
5. DEFINITION FOR DENTAL CERAMICS⁶ An inorganic compound with non metallic properties typically consisting of oxygen and one or more metallic or semi metallic elements (e.g ;Aluminium, Calcium, Lithium, Mangnesium, Potassium, Sodium, Silicon, Tin , Titanium And Zirconium)that is formulated to produce the whole or part of a ceramic based dental prosthesis 5
6. DEFINITION FOR PRESSABLE CERAMICS ⁶ • A ceramic that can be heated to a specified temperature and forced under pressure to fill a cavity in a refractory mold 6
7. HISTORY OF DENTAL CERAMICS ⁶ • 1789-first porcelain tooth material by a French dentist De Chemant • 1774- mineral paste teeth by Duchateau in England • 1808-terrometallic porcelain teeth by Italian dentist Fonzi • 1817- Planteu introduced porcelain teeth in US • 1837- Ash developed improved version of porcelain teeth 7
8. • 1903 – Dr.Charless introduced ceramic crowns in dentistry he fabricate ceramic crown using platinum foil matrix and high fusing feldspathic porcelain excellent esthetics but low flexural strength resulted in failure • 1965- dental aluminous core Porcelain by Mclean and Huges • 1984- Dicor by Adair and Grossman 8
9. 9
10. VARIOUS ALL CERAMIC SYSTEMS Aluminous core ceramics Slip cast ceramics Heat pressed ceramics Machined ceramics Machined and sintered ceramics Metal reinforced system 10
11. MICROSTRUCTURAL CLASSIFICATION⁵ Category 1: Glass-based systems (mainly silica) Category 2: Glass-based systems (mainly silica) with fillers usually crystalline (typically leucite or a different high-fusing glass) a) Low-to-moderate leucite-
Recent advances have improved dental composite materials. Composites contain resin and inorganic fillers to increase strength while decreasing problems from resin such as shrinkage. Larger filler particles improve strength but smoothness while smaller fillers enhance esthetics. Novel composites aim to reduce shrinkage through techniques like silorane resin which uses a different polymerization or bulk fill which can be placed in 4mm layers. Other trends include nano-filled composites with ultra-small particles achieving high filler loading and strength, and smart composites which release ions to prevent decay. Indirect composites can be contoured outside the mouth but still experience shrinkage during cementation. Overall composites continue advancing but shrinkage remains a challenge.
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.for more details please visit
www.indiandentalacademy.com
This document provides an overview of denture base materials. It discusses the definition of a denture base and ideal properties. Denture base materials are classified as metallic or non-metallic. A history of materials used from the 18th century to present is provided, including vulcanite, acrylic resin, and newer polymers. Types of denture base polymers are described, including heat-cured acrylic resin, auto-polymerizing acrylic, and alternatives like fiber-reinforced polymers. Methods of polymerization and various commercial brands are also summarized.
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
This document discusses dental casting investments, which are materials used to form molds for casting dental restorations like crowns and bridges. It describes the components of investments, including refractory materials like silica, binders like gypsum or phosphate, and modifiers. It explains the properties investments must have like strength, expansion to compensate for shrinkage, and smooth surfaces. It covers the different types of investments including gypsum-bonded, phosphate-bonded, and silica-bonded and their appropriate uses and temperature ranges. It also discusses factors that affect the investments' setting expansion to help compensate for casting shrinkage.
This document discusses finishing and polishing of restorative materials in dentistry. It defines finishing as removing surface defects from contouring, and polishing as providing luster to a surface. Finishing and polishing are important for oral health, function, and aesthetics as they reduce plaque accumulation, staining, and irritation. The document outlines the principles, mechanisms, instruments, and procedures for cutting, grinding, finishing and polishing restorative surfaces. It also reviews different types of abrasives and their uses.
Calcium hydroxide cements were introduced by Hermann in 1920 as an alternative to viewing exposed pulps as "doomed organs." Calcium hydroxide cements promote healing in clinical situations by creating an alkaline environment. They are formed through a reaction of calcium oxide with water to create calcium hydroxide. Typical calcium hydroxide cements are composed of calcium hydroxide, zinc oxide, zinc stearate, and ethyl toluene sulphonamide. They set through exothermic chemical reactions, have biocompatibility that can destroy bacteria and initiate reparative dentin formation, but have low strength and solubility in moisture.
1. Etchant acid, also known as phosphoric acid, is used to condition tooth enamel prior to placing restorative materials like resins, sealants, and adhesive cements. It demineralizes the enamel, creating micro pores to achieve a strong bond between the material and tooth.
2. The acid is applied for 15-60 seconds and then rinsed thoroughly before the restorative material is placed. This micro-etching of the enamel improves retention of the restoration.
3. For ceramics, hydrofluoric acid is used which also etches the material by creating channels, allowing chemical bonding between the ceramic, silane, and resin for strong adhesion.
Indirect restorations are fabricated outside of the mouth using laboratory processed composites or ceramics. They are indicated for large defects or esthetic areas and provide better physical properties than direct composites. However, they have increased costs and time. Tooth preparation for indirect restorations requires rounded line angles, occlusal convergence, and extension to sound tooth structure. Impressions are needed to fabricate the restoration on a working cast.
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 discusses dentin bonding agents. It provides background on adhesion and the challenges of bonding to dentin compared to enamel. Key points discussed include:
- Conditioning of dentin is needed to remove the smear layer and expose collagen fibers. This can be done chemically using acids or chelators.
- Primers are then used which contain both hydrophilic and hydrophobic monomers. They displace water from the moist collagen network and allow resin infiltration.
- The concept of "wet bonding" was introduced, in which acid-etched dentin is kept moist during bonding to maintain the expanded collagen network for resin penetration.
The document discusses various die materials and systems used for indirect restorations. It defines a die as a positive reproduction of a prepared tooth used to fabricate restorations outside the mouth. Common die materials include gypsum, resins, metals and polymers, each with advantages and disadvantages. Removable die systems like dowel pins, Di-Lok and Pindex are discussed which allow repositioning of dies in the working cast for wax pattern fabrication. Proper selection of die material and system depends on factors like accuracy, strength and compatibility with impression materials.
Composite Resin Luting cements (2nd edition) presentation powerpoint
A type of dental cement
Used for cementation of indirect restorations & brackets
A summary of five textbooks
The document provides an overview of base metal alloys used in dentistry. It discusses the history and classification of dental casting alloys including cobalt-chromium, nickel-chromium, and titanium-based alloys. The ideal requirements, composition, properties, applications and references of various base metal alloys are described in detail over multiple pages.
The document discusses various materials used in maxillofacial prosthetics. It describes ideal materials as being biocompatible, flexible, colorable, chemically stable, easy to process, and strong. Room temperature vulcanizing materials and modeling materials like clay, plaster, and wax are introduced. The fabrication phase uses extraoral materials like acrylics, vinyl polymers, and elastomers like polyurethane and silicone, which are considered most desirable due to their strength. High temperature vulcanizing silicone provides good strength and detail but requires specialized equipment for processing.
This document discusses dental porcelain, including its composition, manufacturing process, strengthening methods, and applications in ceramic and metal-ceramic restorations. Dental porcelain is a type of ceramic composed of kaolin, silica, and feldspar that is fired at high temperatures. It is used for ceramic crowns, veneers, and metal-ceramic restorations due to its biocompatibility, esthetics, and thermal properties matching enamel and dentin. However, porcelain is also brittle with low tensile strength, so various strengthening techniques are used. Metal-ceramic restorations bond porcelain to metal frameworks, requiring thermal and chemical compatibility between the materials.
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.
This document discusses various types of additives used in polymer processing and their functions. It describes additives like stabilizers, lubricants, plasticizers, fillers, fibers, coupling agents, antistatic agents, slip agents, anti-block agents, nucleating agents, optical brighteners, colorants, anti-aging additives, impact modifiers, flame retardants, blowing agents, and master batches. It provides examples and explains how each additive type alters polymer properties or facilitates processing to achieve the desired characteristics in final products.
The document discusses different types of dental luting cements including zinc phosphate, polycarboxylate, glass ionomer, resin-modified glass ionomer (RMGI), and resin cement. Resin cement provides superior bond strength compared to other cements, bonds well to various restorative materials, and has low solubility resulting in reduced microleakage. Proper preparation and application techniques are required when using resin cement to ensure optimal adhesion.
The document discusses advanced manufacturing techniques using plastics and thermoplastics. It begins by describing some limitations of conventional materials and how plastics offer benefits like ease of manufacturing and versatility. It then classifies plastics into thermoplastics, thermosets and elastomers. The bulk of the document focuses on thermoplastics, describing their properties including glass transition temperature, behavior under temperature conditions, orientation, and water absorption. Examples of commonly used thermoplastics are provided along with applications and potential future developments in the field.
This document provides an overview of dental composites, including:
- A brief history of composites from the 1850s to present day
- Definitions, indications, advantages and disadvantages of composites
- Classifications based on filler particle size and curing method
- Composition of composites including resins, fillers, and photoinitiators
- Polymerization processes for chemical, light, and dual-cured composites
- Properties and clinical considerations for different composite types
The document serves as a reference on the development and characteristics of dental composites.
Restorative resins have evolved from early silicate-based materials to modern resin composites. Resin composites are composed of a resin matrix reinforced with inorganic filler particles. They are classified based on filler size and curing mechanism. Developments include microfilled, small particle, and hybrid composites, as well as flowable and packable composites. Resin composites are used for anterior and posterior restorations. Successful use requires acid etching of enamel, dentin bonding agents, and incremental placement techniques to reduce polymerization stresses.
Dental cements have evolved over time from early formulations like zinc phosphate cement to modern resin cements. Ideal cement properties include biocompatibility, fluoride release, strength, and bonding to tooth structure. Mechanisms of bonding include mechanical interlocking, micromechanical bonding through surface treatment, and chemical bonding. Common cements discussed include zinc phosphate, zinc oxide eugenol, glass ionomer, and resin cements. Recent advancements aim to increase strength, antibacterial effects, and remineralization through additions like nanoparticles, arginine, and bioactive glass. Overall, dental cements have greatly improved but further optimization of new formulations is still needed for clinical performance.
1. Bonding involves cleaning the enamel, conditioning it using acid, and applying adhesive resin to chemically bond brackets. Proper moisture control and enamel pretreatment are important for achieving optimal bond strength.
2. Various adhesive materials like composite resins, glass ionomer cements, and self-etching primers are used. Different light curing sources help polymerize the adhesives. Trays can aid in accurate bracket placement.
3. Debonding requires carefully removing brackets and cleaning residual adhesive to minimize enamel damage. Daily fluoride and good oral hygiene help prevent decalcification during treatment. Polishing can remove superficial discoloration when remineralization is exhausted.
Performance Coating Additive by DELTA specialtiesAbhay Mehrotra
This document discusses various performance additives used in coatings. It describes additives for processing/storage, application, film formation, and service life of coatings. Specific additive types are outlined for each stage including dispersing agents, defoamers, coalescing agents, cross-linking agents, and more. Mechanisms, advantages, factors affecting dispersion and defects caused by poor stabilization are explained. The document also provides information on Delta Specialties' line of performance additives.
This document discusses dental composites, which are used for dental restorations. It describes the components of composites, including the matrix, fillers, and coupling agents. It explains the types of fillers and their purposes. It also discusses the different types of composites based on particle size, including microfilled, small-particle filled, hybrid, packable, and flowable composites. The document outlines the polymerization process and classifications of composites according to curing system and particle size. Advantages and applications of composites are provided. Considerations for bonding composites to enamel and dentin are also summarized.
Resin composites are dental restorative materials made of an organic resin matrix and inorganic filler particles. They contain monomers like bis-GMA that polymerize to form the matrix. Fillers like silica improve properties and radiopacity. Coupling agents bond fillers to the matrix. Composites are classified by filler size and polymerization method. Proper placement techniques and acid etching improve bonding to tooth structure. While esthetic and conservative, composites also have limitations like polymerization shrinkage, sensitivity, and wear over time.
This document discusses different types of modified heat-cured acrylics used in dentistry. It describes rapid-cured acrylic which can cure in boiling water in 20 minutes but has higher residual monomer levels and lower mechanical properties. High impact acrylic contains rubber beads for improved strength and reduced crazing. Fiber and metal-reinforced acrylic can incorporate materials like carbon, glass or metal powders but some fibers may discolor or irritate tissues. Chemically-cured acrylics use chemical activators instead of heat to polymerize at room temperature in 3 hours but have lower strength and higher shrinkage. Light-cured acrylic sheets do not contain MMA monomer and are cured with a light
The document discusses polyvinyl chloride (PVC) paste polymerization and plastisols. It describes suspension, emulsion, and microsuspension polymerization methods. Plastisol applications include leather cloth, textiles, coatings, and more. India's PVC paste resin demand and imports are growing about 7% annually. Primary PVC particles from emulsion polymerization are 0.1-2 micrometers and form porous secondary particles after spray drying. Plastisol rheology depends on particle size distribution and residual emulsifiers. Upon heating, plasticizers diffuse into PVC particles to form a homogeneous material, with complete fusion providing maximum properties.
Dentin bonding agents have evolved over time from early generations that provided only weak bonds to later generations that form stronger hybrid layers and resin tags. The current seventh generation agents are truly all-in-one adhesives that etch, prime and bond dentin in a single step without requiring mixing for greater simplicity. Earlier generations required multiple steps and materials to etch, prime and bond dentin and provided increasing bond strengths up to the current gold standard of 18 MPa for fourth generation total etch systems.
Dentin bonding agents have evolved over several generations to improve bonding to dentin. Early generations in the 1970s used primers like NPG-GMA and GPA-DMA but provided poor bonding. The second generation in the late 1970s used phosphate monomers to improve bonding strength. The third generation in the mid-1980s aimed to modify or remove the smear layer without disturbing tubule plugs. The fourth generation introduced the total etch concept in the 1980s and created a hybrid layer through resin infiltration into partially decalcified dentin. Later generations simplified application and improved bonding in moist conditions, with sixth generation agents establishing strong bonding through multiple mechanisms.
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This document discusses dental resin used for denture bases. There are several types of denture base resins classified by their polymerization method. Heat-activated denture base resin is most commonly used. It involves a powder made of polymethyl methacrylate and a liquid of methyl methacrylate. The powder and liquid are mixed together and packed into a mold made from the patient's impression. The packed resin is then cured using heat to initiate polymerization.
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The document discusses concepts and philosophies related to full mouth rehabilitation. It defines full mouth rehabilitation as restoring the form and function of the masticatory apparatus as close to normal as possible. Occlusion plays a key role in establishing synchronous harmony between teeth, TMJ, and muscles of mastication. The selection of the proper occlusal scheme is important for prosthetic rehabilitation. Various philosophies and concepts are discussed, including gnathological concept, mutually protected occlusion, group function, balanced occlusion, Pankey-Mann-Schuyler philosophy, and Hobo's twin table technique. Cusp shape factors, amount of disocclusion, and influences on disocclusion are also covered.
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lect dental-polymers.ppt including heat and coldmanjulikatyagi
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Temporomandibular disorders (TMD) are the most common non tooth-related chronic orofacial pain conditions. Diagnosis requires a multidisciplinary approach due to the complex nature of each case. TMDs can be classified into masticatory muscle disorders, temporomandibular joint disorders, chronic mandibular hypomobility, and growth disorders. Common causes include trauma, inflammation, systemic diseases, and prolonged immobilization. Management involves both conservative and definitive treatment depending on the specific disorder.
This document discusses various mechanical properties that are important for evaluating dental materials, including their ability to withstand forces in the oral cavity. It defines key terms like stress, strain, elastic limit, yield strength, toughness, ductility and describes how these properties are measured. Properties like elastic modulus, resilience and strength values are important for determining a material's stiffness, ability to absorb forces without permanent deformation, and maximum stress before failure. Understanding these mechanical behaviors can help select appropriate materials for different dental applications and restorations.
The document discusses principles of tooth preparation for fixed partial dentures. It covers objectives like reducing tooth structure for retention while preserving healthy tooth structure. Principles include conservative preparation with minimal taper and preservation of tooth structure. Margin placement should be supragingival when possible. Margin designs like chamfer and shoulder are described. Tooth preparation creates retention and resistance for fixed restorations.
DIAGNOSIS AND TREATMENT PLANNING OF EDENTULOUS PATIENTS (2).pptmanjulikatyagi
This document discusses the diagnosis and treatment planning process for edentulous patients requiring complete dentures. It emphasizes the importance of a thorough patient assessment involving medical history, clinical examinations, diagnostic procedures and observations. The goal is to understand the patient's physical and psychological condition to determine a treatment plan that meets their expectations. A proper diagnosis recognizes any issues, formulates an appropriate plan, carries out necessary examinations and interprets the results. This process requires developing trust with the patient and familiarizing oneself with their overall oral condition to achieve successful complete denture therapy.
This document discusses the biomechanics of edentulism and complete denture support. Key points include:
- Loss of teeth results in loss of periodontal ligament support and alterations to the mechanisms of force transmission during functions like chewing.
- Complete dentures rely on mucosal support over a much smaller area compared to periodontal ligaments. They are also subject to residual ridge resorption over time.
- Chewing forces are significantly lower with complete dentures versus natural dentition. Movement patterns during functions like chewing are similar but dentures cannot substitute fully for natural teeth.
This document discusses biomaterials used in dental implants. It begins by introducing various biomaterial options for implants, including metals, ceramics, polymers, and natural materials. It then discusses the history of biomaterial development, starting with ancient attempts to replace teeth and progressing to modern materials like titanium. The document also covers important properties to consider when selecting and evaluating biomaterials, such as mechanical strength, biocompatibility, corrosion resistance, and how materials can be modified.
This document discusses dental ceramics. It defines ceramics as inorganic, non-metallic materials that are crystalline in nature and formed from compounds of metallic and nonmetallic elements. Dental ceramics are characterized by properties like biocompatibility, esthetic potential, hardness, and chemical inertness. They can be crystalline or amorphous and are classified based on factors like firing temperature, processing method, and microstructure. Common types used in dentistry include feldspathic porcelain, aluminous porcelain, and glass ceramics. Dental ceramics have various applications and are indicated for uses like crowns, veneers, and fixed dental prostheses depending on their composition and properties.
Ceramics are inorganic, non-metallic materials formed from chemical and biochemical stable substances. Dental ceramics contain a glassy matrix reinforced by crystalline structures such as leucite, alumina, and silica. Dental porcelains are composed of feldspar, silica, and kaolin, which are blended and fired to form the ceramic. Metal-ceramic restorations consist of a metal coping covered with opaque, dentin, and enamel porcelain layers that are bonded to the metal through mechanical interlocking and chemical bonding between metal oxide layers and the ceramic.
Soldering and welding are processes to join metal components. Soldering involves melting a filler metal below the melting points of the components being joined. Welding directly melts the components together without a filler. Common types of soldering include soft, hard, and brazing based on the filler metal temperature. Welding techniques include spot welding, laser welding, and tungsten inert gas welding. Key factors for a strong joint include clean surfaces, proper temperature, timing, and gap width between components. Defects like porosity or distortion can weaken the joint if processes are not followed correctly.
1. The document discusses different types of elastic impression materials used in dentistry including their history, properties, and recent advances.
2. The main elastic impression materials discussed are elastomers/rubber base materials like polysulfides, condensation silicones, addition silicones, and polyethers.
3. Recent advances include visible light cured impression materials which offer controlled working times and excellent properties but require special trays and can be difficult to cure in all areas.
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Temporary removable partial dentures are interim prostheses used until a definitive prosthesis can be provided. They aim to reestablish esthetics, maintain space, improve tolerance to wearing a prosthesis, and condition tissues. Different types include interim, transitional, treatment, and immediate RPDs. Acrylic RPDs are made with a resin base and acrylic teeth connected with wire clasps. They are indicated when cost is a concern or temporary use is needed. Care must be taken to minimize tissue damage and maintain oral hygiene with acrylic RPDs.
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The document discusses various mechanical properties of materials including stress, strain, tensile strength, compressive strength, shear strength, modulus of elasticity, ductility, resilience, toughness, and hardness. It defines these terms and describes methods for measuring properties such as stress, strain, hardness, and strength. For example, stress is defined as force per unit area and can be measured using a three-point bending test. Hardness is the resistance of a material to indentation and can be measured using Knoop or Vickers indentation tests.
This document discusses indirect retainers in removable partial dentures. It defines an indirect retainer as a component that assists the direct retainer in preventing displacement of the distal extension denture base through lever action on the opposite side of the fulcrum line. The functions of indirect retainers are to reduce twisting forces and help stabilize the denture. Factors like fulcrum lines, connector rigidity, and rest effectiveness determine the indirect retainer's effectiveness. Common types include auxiliary occlusal rests and canine extensions. Properly designing indirect retainers based on a patient's dentition can improve the support and stability of a removable partial denture.
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1. Provisional restorations protect teeth during fabrication of final restorations and help gain patient confidence. They must fit well, have proper occlusion/contacts, and be esthetic.
2. Common materials are acrylics and resin composites. Acrylics are inexpensive but can discolor. Resin composites shrink less and cause less heat, but are more expensive.
3. Material properties like marginal accuracy, strength, and polishability influence how well provisionals function and maintain health until replacement by final restorations.
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4. 4
Denture base function
Distributes pressure over a wider area
So reducing bone resorption
Retains artificial teeth
Replaces missing tissue
Forms a seal for retention
6
5. 5
Denture Base materials
Carved ivory
Carved Wood
Vulcanite; dark, opaque
(Vulcanised rubber)
Highly cross-linked Acrylic resin
Other Resin and plastic
alternatives
0
6. 6
Plastic acrylic teeth
Bind chemically to the denture
Can be adjusted
Not cause wear of opposing tooth
Good colour match
Minor resiliency
Wear under high force occlusion
May stain with time
6
19. 19
Terminology
Monomer + monomer = polymer
Monomer1 + monomer2 = copolymer
Oligomonomer= 2-4 monomers
Poly = many
Mono = single
Mer = unit
Oligo =several
6
20. 20
Types and molecular weight
Addition polymerisation:
No by products
Polymer mwt = Σ mwt monomers
Condensation polymerisation:
By products are produced and lost in
thefinal product
Polymer mwt ≠ Σ mwt monomers
6
21. 21
Morphology
of spatial arrangements
Linear or chain polymerisation
Easily manipulated, stretched, bent,
thermoplastic, Hard
e.g. fitting surface of acrylic teeth- better
binding to denture base
Branched polymerisation
Easily manipulated, stretched, bent,
thermoplastic, More hard
6
22. 22
Cross-linked polymerisation
Strong, stiff, thermoset, wear resistant
E.g. Denture base materials, Occlusal
surfaces of actylic teeth
Coiled chains
Flexible
e.g. impression materials
Morphology
of spatial arrangements
6
23. 23
Crystalline polymers
Very regular arrangement in space:
strong,
stiff,
absorb less water.
Amorphous or glassy polymers
Irregular arrangement
Behaves as a brittle solid
Morphology
of spatial arrangements
6
24. 24
Plasticizers effects
Added to stiff, glassy uncross-linked
polymers
Lowers glass transition temperature (Tg)
Become
rubber-like,
Flexible
less brittle
6
25. 25
Dimensional and thermal
changes
Expansion on polymerization, exothermic
Contraction on polymerization
21vol.% If unfilled acrylic resin
6% denture resin
1-3% composites
Expansion on swelling in water
Expansion or warpage on thermal change
and reheating
6
27. 27
Ideal properties
Natural appearance
Easy processing
Easy to clean
Easy to repair
Inexpensive
Biocompatible
Resistant to bacterial
contamination
High strength, stiffness,
hardness, toughness,
fatigue resistance
•Low density
•Radiopaque
•High thermal
conductivity
•High modulus of
elasticity, impact
strength
•Abrasive resistance
•Dimensionally stable
•Accurate reproduction
of surface detail
28. 28
Curing methods
Chemically cured
Tertiary amine ( dimethyl-p-toluidine or sulfinic acid)
(accelerator)
Benzoyl peroxide (initiator)
Hydroquinone (inhibitor)
Heat cured
Heat and pressure control
Avoids porosity
Maximizes conversion of monomer to polymer
Light cured
Photo-initiators (camphorquinone),
Blue light,
Used for: record bases, custom tray, denture repair
29. 29
Heat cured acrylic resin
Powder ( can have limitless life)
Beads or granules of polymethyl methacrylate
Initiator (benzoyl peroxide)
Pigments/dyes (colour vitality as cadmium, iron, organic dyes)
Optical opacifiers (tio2/zno)
Plasticizers (ethyl acrylate (internal), dibutylphthalate (external) to
make dough easier)
Synthetic fibres (nylon)
Coloured fibres (blood vessels)
Liquid ( in dark bottle, avoid contamination by
powder)
Methyl methacrylate monomer
Inhibitor (hydroquinone)
Crosslinking agent
(diethylene glycol dimethacrylate, (1,4 butylene glycol dimethacrylate)
Bead Polymer
30. 30
Chemical cured resin
Cure is initiated by a tertiarv amine (e.g. Dimethyl-
p-toluidine or sulfinic acid)
Absence of heat:
Lower molecular weight material
Lower strength properties
Higher residual monomer in the resin
Color stability is not as good- yellowing
Less contraction on cooling to room temp
Polymer beads are smaller
Faster dissolution in the monomer to produce a dough
Doughy stage is reached before the addition curing reaction –
mix viscosity is high and prevents the adaptation of the mix to
the mould walls or cast -keep readapting
Lowering of the glass transition temperature
Less build-up of internal strain
Highly susceptible to creep- distortion when in use.
31. 31
Light activated materials
Components:
Urethane dimethacrylate matrix
Acrylic copolymer
Silica filler to control rheology
Forms
Sheets
Ropes
Curing
Light chamber- 400-500 nm
Photo-initiators (camphorquinone),
Teeth added in a second exposure over the base
Used for
Record bases
Custom tray
Denture repair
Hardness and impact strength ≈ heat cured resin
Elastic modulus < heat cured resin; deform under
mastication
Less shrinkage (3%) better fit
Less residual monomer
32. 32
Auto-polymerizing, pour acrylic
Reducing agent (tertiary aromatic amine or barbituric
acid derivative, NN’-dimethyl-p-toluidine) reacts with
peroxide at room temp.
Excellent detail reproduction
To be able to pour in mold, balanced size, mwt,
plasticizers and xlink agents
Reversible hydrocolloid (agar) mold can’t resist teeth
movement during pouring
Hydro pressure flask reduces air bubbles and
monomer porosities
Difficult to dewax, less monomer binding to teeth
Shortcomings:
residual monomer
↓ Cross link densities
Creep
Variety of products
33. 33
High-impact acrylic
A rubber phase is added (phase inversion)
Uniformly distributed
Rubber cored polymer
Types
Butadiene + styrene = polystyrene butadiene rubber
Butadiene + MMA
PMMA + polystyrene butadiene rubber + poly(2,3-
dibromopropyl methacrylate) for opacity
PMMA = lucitone 199
Lightly xlinked or no cross linking agent is added
Rubber has a craze inhibitory effect
34. 34
Experimental types of acrylic
All aim to increase impact strength and stiffness
Glass reinforced acrylic (failed)
Fibers may irritate patient if denture fitting surface was
abraded
Carbon fibers
Black color- used only in lingual areas
Kevler fibres (poly-p-phenylene terephthalamide)
Straw color
Poor bond between fibers and matrix
Difficult to pack
Black shadow- used only in lingual areas
35. 35
Experimental types of acrylic
Added Bis-GMA and fiber
Flexural strength ≈ ceramics
Can be used as lingual bars and connectors
Experimental (mwt polyethylene fiber-reinforced)
Neutral color
Low density
Biocompatibility
Surface treated to enhance fabrication
Time consuming
36. 36
Types of acrylic
Other (polystyrene,epoxy, SS)
PMMA Adhesion to
Metal- use adhesive primers
untreated porcelain teeth with organo
silane compounds
39. 39
Setting reaction
Mixing of powder and liquid cause monomer diffusion and
softening of the surface of the powder producing the following
gelling stages:
Ratio P/L (2/1 wt%, 1.6 -1 vol%)
Sandy- initial melting of beads (not used)
Stringy or sticky- entanglements with swollen beads and
thickened interstitial monomer (not used)
Dough- gelation (used)
Rubbery- monomer penetrates to the core of beads,
plasticizing them, ↓Tg (not used)
41. 41
Manipulation issues
Curing before monomer diffuse to bead
(before dough stage)
↓ flexural strength
cracks between linear polymerised interstitial gel and cross
linked beads
More shrinkage contraction by the loss of pressure produced
by the dough to compensate for it
Curing in dough stage
monomer penetrate the beads
dissolves beads allows cross-linking agent to penetrate
interpenetrating polymer network IPN.
Packing in the rubber stage
Less extrusion of excess acrylic from flask
Extra pressure in the mould
Fracture the cast
less flow around teeth
Dislodgment of teeth into mould
42. 42
Manipulation issues
Control of color
Pigments position
Inside beads
surface of beads
– polymer should be added to the monomer slowly so it will not
washed off by too rapidly
Blood vessel resembling Fibers aggregate in the bottom
of bottle
– Shake powder well before use
Mould Lining
resin may penetrate rough plaster and adhere
a separating medium must be employed
solution of sodium alginate
tin foil.
43. 43
Manipulation issues
Control of Processing strains
Shrinkage in restricted mould cause internal strain
On release of stress (flask opening) it may give
Crazing
Warpage
Distortion
These are reduced by the slightly extra packed material
that flow into shrinkage spaces when temperature is
higher than Tg (heated flask)
Manipulation further reduces strains by
Using acrylic teeth
Cooling the flask slowly
46. 46
Flasking for heat cured resin
Flasking options with acrylic dough:
Trial-packing, trimming, repacking
Packing-only
Poured resin (e.G., Lucitone fas-por)
Injection moulding
Heat and pressure control
Aim to produce radicals and initiate polymerization
Reaction is thermally activated and generates heat as
well
Reaction conversion is about 98 to 99.5%
MMA: tbp = 100c (p= 1 atm); 140c (p= 2 atm)
47. 47
Heat curing cycles
Fast cycle
Cure at 71-72°C for 30-90 min
100°C for 30 min.
Slow cycle = cure at 71-72°c for 10 hrs
[A slow cycle is better with larger amounts of
material.]
[Generally, slow cures result in better
dimensionalaccuracy.]
Other cycles are done as recommended
by manufacturers
48. 48
Heat curing cycles
Rapid heating:
Excess radical release
Extra xlinking and branching of interstitial
polymer
More residual monomer
Reduced toughness
Heat builds up from exothermic rxn
Porosity
Loss of strength
Bad esthetics (opaque and cloudy color)
Possible fouling
49. 49
Heat curing cycles
Slow :
Sufficient radical release
Adequate xlinking and branching between high
mwt polymer chains
Increased toughness
Sufficient radical ends increase monomer
incorporation in growing chains
Xlinking agents polymerized, reducing their
plasticizing effect (in their non bound state) and
reduce creep
Produce an annealing effect easing stresses
produced from shrinkage, reducing crazing and
distortion
50. 50
Heat curing cycles
Pressure control
Places compressive force
Compensates for polymerization shrinkage
Increase flow of dough around teeth, more
monomer wetting and surface dissolution,
stronger bond
Oozes out excess dough
Some hybrid systems begin polymerization
from one side to allow dough to cover for
shrinkage
53. 53
Denture Radiolucency
Problems when accidents displace fractured
segments
Lungs
Skull
stomach
Salts and fillers reduce esthetics, strength
Organo-metalics are toxic
Bromine containing organics lack heat stability, must be
added in quantities that plasticize the denture, causing creep
and water sorption
Phase separating bromo-polymer in beads reduce the
previous effects
54. 54
Mechanical properties
Failure to Moderate strengths:
impact resistant denture is low
Low elastic and flexural modulus
lack of fracture toughness
30% of denture repairs involve midline fractures
which are most prevalent among upper dentures.
dropped denture does not necessarily break instantly
a crack continue to grow and failure due to flexural
fatigue.
Failure due to poor quality processing
Lack of bonding between the resin and the acrylic teeth
and weak interface
Crazes due to processing faults or exposure to solvents
is another possibility.
Creep
Reduced by cross linking
Heat cured < cold cured
55. 55
Internal denture porosity
Inherent porosity:
Not seen by vision
1-2% of residual
monomer
Leaks
Replaced by fluids
Minimized by
Use heat cured resin
Pack denture under
correct pressure
Use correct P/L
Use the glaze after
polishing
56. 56
Internal denture porosity
Irregular porosity:
Seen by vision
Not regular on
denture surface
P/L heterogeneity
Air incorporation
(spherical pores)
Minimized by
Use correct P/L
Add liquid first
Mix well
Cover the mix before
dough stage
Can use the vibrator
57. 57
External denture porosity
Irregular surface
deficiencies:
Seen by vision
Insufficient pressure
Dough was not molded
correctly by hand leaving
surface blisters and pores
Insufficient dough
Minimized by
Mold dough by hand
into small areas
Place sufficient
material in flask
Pack under correct
pressure
58. 58
External denture porosity
Irregular porosity:
Shrinkage by
polymerisation (5-8% vol
or 0.2 -0.5% linear)
Further shrinkage by
cooling to room
temperature
Can compensated for by
the post dam technique
Minimized to by
Pack under pressure
Slight extra denture
material can overcome
shrinkage and
maintain pressure
(single packing)
Pack in dough stage
59. 59
Internal denture porosity
Gaseous porosity
Seen by vision
Volatisation of
monomer by
Localized MMA boiling
Common in thicker
portions
Minimized by
Avoid high processing
temperatures
Avoid extra monomer
than recommended for
P/L
Raise heat slowly and
evenly around the
flask
60. 60
Gaseous porosity
Avoid high processing temperatures
0
20
40
60
80
100
120
140
160
0 10 20 30 40 50 60 70 80 90
100
Temperature
0
C
Time (min)
Correct
cycles
Incorrect
cycle
61. 61
Crazing
Area of localised region of high plastic
deformation which may fill by voids
Crazed region can still support stress
As the voids in the crazed region grow, they become
separated only by thin fibrils of polymer
Fibrils fail and a crack is formed
Crack will grow under an externally applied load
Cause denture failure by brittle fracture.
Caused by
Internal strains in flask
Heat (due to polishing)
Differential contraction around porcelain teeth
Attack by solvents such as alcohol
Reversible Irreversible
CRAZE CRACK
62. 62
Crazing
Avoid internal strain during polymerisation
Slow cooling of the flask
Use single trial packing
Use cross linked polymer types
Avoid extra stress during function
Use acrylic rather than porcelain teeth
Do not overheat on polishing
Keep denture away from solvents
Avoid denture drying
Polish after each adjustment
Use glazes for surface
Reversible Irreversible
CRAZE CRACK
63. 63
Dimensional changes on
processing
Expansion on heating flask; heat evenly
Expansion on polymerization, exothermic
Contraction on polymerization (21vol.%);
Contraction on cooling to room temperature;
Expansion on swelling in water;
Expansion on thermal change to 32c.
Net result– should be near zero
65. 65
Adverse reactions to PMMA
Most common in dental
laboratories
Associated with regular
contact with monomer
when handling the
dough
Must avoid direct
contact
Rubber gloves may not
provide sufficient
protection
Barrier creams can help
Irritant contact
dermatitis
66. 66
Adverse reactions to PMMA
Allergic contact dermatitis
Usually associated with
release of
residual monomer
Benzoic acid
Types
Immediate
Delayed hypersensitivity
(type IV)
Heat cured resin < chemical
cured
Must ensure full cure of denture
Avoid relining procedures
May use an extra cycle of
polymerisation – but denture
may warp
May need to consider
alternative material such as
polycarbonate if Delayed
hypersensitivity
67. 67
Adverse reactions to PMMA
Further reading:
Hensten-petterson & jacobsen. J prosthet dent
1991; 65: 138
Kaber. Int dent J 1990; 40: 359
Http://www.Shef.Ac.Uk/uni/project/arrp/
68. 68
Thermal properties
Low Thermal conductivity
during denture processing heat cannot escape – prone to
gaseous porosity
isolates from any sensation of temperature – throat burns
High Coefficient of Thermal Expansion
Porcelain teeth may be lost due the differential expansion
and action
Warpage if denture is cleaned with hot water
69. 69
Water Sorption
PMMA will absorb water by polar nature (1.0-2.0%
wt)
May compensate for processing shrinkage
Weeks of continuous immersion in water to reach a
stable weight
Solubility
Solvents (e.G. Chloroform, alcohol)
Xlinked are insoluble in most of fluid intakes
Weight loss will occur, due to leaching of the
Monomer
Pigments and dyes.
70. 70
Ideal properties achieved?
Natural appearance
Easy processing
Easy to clean
Easy to repair
Inexpensive
Biocompatible
Resistant to bacterial contamination x
High strength, stiffness, hardness, toughness X
Low density
Radiopaque X
High thermal conductivity X
Dimensionally stable X
Accurate reproduction of surface detail
73. 73
Injection molded plastic
Types
Polycarbonates
Nylon
Advantage:
Consistent mwt
Substitute acrylics in sensitive patients
Disadvantage
Must use dry mold, slow heating and cooling
Under filled molds by inadequate spruing or underheating
Low melt temp cause high injection forces, moving teeth in
mold
Cost of equipment
Difficult to attach to teeth
Small market segment
Can explode if high heat and wet molds
Overheating cause depolymerization, oxidation, porosties
Loss of strength
Bad esthetics (opaque and cloudy color)
Possible fouling
74. 74
Polycarbonates
Tough plastic
Injected in dry molds
A high melt viscosity
Problems in binding to teeth
May de-polymerize explosively in the
presence of heat and water
No cross linking –
Poor solvent resistance
Poor craze resistance
75. 75
Nylons and polyamides
Polyamide = diacid + diamine
Conventional nylon failed
Excessive water sorption
Poor creep resistance
Biodegradation
Glass (beads or fibers) reinforced nylon
Less water sorption
Fibers better in stiffness(≈ acrylic) than beads
Fibers may irritate patient if denture fitting surface was abraded
80. 80
Denture base reprocessing:
Hard and soft tissue changes every 5-8 years
Require modifying denture base:
Relining resurfacing of the tissue surface
Rebasing replacement of entire denture
base
81. 81
Soft denture lining material
Uses:
After surgery
Immediate dentures
Sores
Undercuts which are not removed by surgery
Ill fitting denture
can be done
In lab
Chair side
82. 82
Ideal lining material properties
Durability: but hardens in short time
(1-4w, 1-3 y)
Dimensional stability
Resistance to fouling
Water absorption
Osmotic presence of soluble material
Resistance of Biodegradation
Could it bond old acrylic
Inhibit candida growth
83. 83
Lining materials–acrylic based
Glassy MMA + high conc. of plasticizers
Plasticizers:
Free: diffuse out reducing the resiliency
Bound in cured matrix – failed clinically
Has lower rate of polymerization
Phase separation
Water accumulate in plasticizer rich phase
Soluble impurities cause more osmotic pressure
Swells and distorts
Discoloration
Bad taste
Exothermic rxn
Bad taste
84. 84
Lining materials–acrylic based
Soft acrylics that have ↓Tg
EMA (ethylmethacrylates)
Beads coploymer
Ethyl methacrylate + isobutyl methacrylate
Ethyl methacrylate + ethoxyethyl methacrylate
– Have unpleasant odour
Monomer
MMA Tg > room temp Less irritant to patients
Isobutyl methacrylate Tg < room temp (polished after placing
in iced water), Dimensional instability
Plasticizer in monomer trapped in beads (25-50%)
Phthalate ester – leach out by time
Avoid heat, strong bleaching agents that reduce resilience
85. 85
Lining materials–acrylic based
Soft acrylics that have ↓Tg
Hydroxy EMA
Water is the plasticizer
Swelling of liner may make it distort
Ions enter and may crystallize inside matrices thus
hardening the liner
Polymerisable plasticisers
Beads ploymer
Ethyl methacrylate + isobutyl methacrylate or
Monomer
Alkyl maleate or
Alkyl itaconate + Tridecyl methacrylate +
2-diethylhexyl maleate, ethylene glycol dimethacrylate
86. 86
Tissue conditioners
Differ from soft lining material by the following
Different viscoelastic properties
Flowable on insertion responding to
– Masticatory forces
– Lingual forces
– Border moulding forces
Increase viscosity on setting
Flows slowly responding to persistent heavy masticatory
forces after setting
– Useful to fill space after tissue swellings resolve
– Can be used as a functional impression
Reaction
Gel formation not polymerization
Alcohol swells beads and ↓ their Tg
Beads become tacky by entanglements and cohesive
strength
87. 87
Tissue conditioners
Differ from soft lining material by the following
Composition
• Old- plasticine
• Old- chewing gum
• Ethyl methacrylate copolymers
• Or small mwt polymers
Plasticisers:
ethyl alcohol or
aromatic esters (butylphthalyl butylglycolate)
hemical cleaning damages the liner
– Use plain soap and water
88. 88
Tissue conditioners
Differ from soft lining material by the following
Alcohol problems:
Leak and replaced by water- so harden days up to 14 days
High conc. Can give a sting sensation
Can give a false positive on breathalyser test
Reduce leach of plasticisers by glazing or semiset MMA
Very susceptible to infection
– Incorporate antimicrobials as
» silver zeolite
» itraconazole
Chemical cleaning damages the liner
– Use plain soap and water
89. 89
Silicon - RTV
Room temperature vulcanizing silicones (RTV)
Polymethyl siloxane polymer
It sets by crosslinking of existing polymers
Heat
Tetraethyl silicate
Condensation minimal xlinking
Poor tear resistance
Poor abrasion resistance
Poor adhesion to denture
Use adhesive or coupling agent
Osmotic pressure effects
Buckling and swelling with water
Poor resistance to cleansers
Biocompatible
Dimensional stability
May foul by Candida
90. 90
Silicon – Heat cured
More xlinking
Poor tear resistance
Adequate adhesion to denture
Can use siloxane methacrylate as a binder to heat
cured additional silicon
Resistant to aqueous environment and Osmotic
pressure effects
better resistance to cleansers
Poor tear resistance
Poor abrasion resistance
92. 92
Denture base hygiene
1. Clean with toothbrush and warm soap-
and-water
2. Use low abrasive cleaners
2. Avoid oxidizing or Cl-containing
materials
• Bleaching the color
• Reduces strengths of denture
• Reduces fatigue resistance
3. Diligently clean both the top and tissue-
borne surfaces
4. Clean with benzalkonioum
94. 94
References
Philips Science of Dental Materials
Dental Materials and Their Selection
Applied Dental Materials
Dental Materials. Clinical Applications for
Dental Assistants and Dental
Introduction to Dental Materials
RPD acrylic materials by Dr Stephen C.
Bayne
Dr Layla Abu- Naba’a