Chapter 43 Restorative and Esthetic Materials PDF

CHAPTER 43 Restorative and esthetic materials ▪ Section of the most appropriate dental material depends on: - The extent of decay - How much tooth structure remains intact - Condition of entire mouth - Location of restoration - Cost factors ▪ Most commo...

CHAPTER 43 Restorative and esthetic materials ▪ Section of the most appropriate dental material depends on: - The extent of decay - How much tooth structure remains intact - Condition of entire mouth - Location of restoration - Cost factors ▪ Most common dental materials: - Silver amalgam (Am) - Composite resin (CR) - Glass ionomer (GI) - Temporary materials - Tooth Whitening products - Gold Alloys - Ceramic castings ▪ Restorative: the ability to remove decay & restore proper function of tooth ▪ Esthetic(aesthetic): restoring to an artistically pleasing appearance ▪ Standardization of dental materials - When a new dental material is developed, the product undergoes a strict evaluation and assessment before it is marketed to the profession. ▪ Criteria for new dental material - Not be poisonous or harmful or irritation to the tissues of the oral cavity & the body - It must help protect tooth and tissues of the oral cavity - It must resemble the natural dentition as closely as possible to be esthetically pleasing - It must be easily formed and placed in the mouth to restore the mouth’s natural contour - It must conform and function despite limited access, wet conditions and poor visibility.  ▪ Dental Assistant needs to know - General characteristic of materials - Selection criteria for each - Preparation of material for each procedure - Set up for each material ▪ Properties of dental materials - Mechanical properties - Thermal properties - Electrical properties - Corrosive properties - Application properties ▪ Mechanical Forces - Average biting and chewing force with natural dentition = 130 – 170lbs molars - A Force is any push or pull-on matter, which produces a stress and a strain - Stress is the internal resistance or force that can cause distortion - Strain Is the change or deformation of material as the result of stress - Stress and strain are applicable to both liquids and solid - Stress and strain go together; you cannot have one without the other Types of Stress and Strain Tensile Stress & Strain: Pulls and stretches the material, like a tug of war Compressive stress & strain: Pushes the material together. Example: Chewing Shear Stress & Strain: The breakdown of the material as a result of something sliding over the 2 areas. Example: cutting with scissors Shear Stress & Strain: The breakdown of the material as a result of something sliding over the 2 areas. Example: cutting with scissors Ductility and Malleability - A measure of a material’s ability to withstand permanent deformation by either tensile or compressive forces Ductility - Ability of material to have its shape changed by being stretched or by being stretched or by a pulling or tensile force without it losing strength or breaking - This property allows a metal to be made into thin wire Malleability - Is the measure of a material’s ability to be extended in all directions by a compressive force, such as rolling or hammering - This property allows a metal to be shaped into thin sheet or plate. Thermal Change - Going from hot coffee to cold ice cream within seconds - Causes contraction and expansion, material pulls away from the tooth causes microleakage or a faulty restoration - Need to protect the pulp from thermal shock Contraction and Expansion - When temperature changes occur, each type of dental material will contract or expand at its own rate - It is essential that the tooth structure and the restorative material have, as nearly as possible, the same rate of contraction and expansion - Significant changes cause a dental material to pull away from the tooth, which can result in microleakage. - This microscopic separation of material and tooth can allow oral fluids, debris, and microorganisms to enter between the restoration and the wall of a cavity preparation. The term for this process is percolation. Electrical Properties - An electrical current or galvanic action, is created when two different or dissimilar metals are present in the oral cavity. - Conditions for this to occur: ◦ Saliva (contains salt), good conductor ◦ Two metallic components of different composition Corrosive Properties - Corrosive is the reaction that occurs within a metal when it is exposed to corrosive factors such as temperature, humidity, and saline. - Certain foods contain metallic forms that cause corrosion of a dental material - The surface discoloration that we see in older amalgam restorations in the mouth is referred to as tarnish - Most corrosion, however, involves surface discoloration and can be removed easily with use of polishing agents Hardness - Any restoration must have enough hardness to resist indentation, scratching & abrasion - Indication of strength & wearability Solubility - The degree to which a substance will dissolve in a given amount of another substance - A material that dissolves easily on the oral cavity is of limited use as it will wash away and leave the tooth structure exposed Application Properties - Flow: ability of the materials to move and fill in the preparation of the tooth - Retention: the ability of 2 different materials to adhere to each other Characteristics of materials will affect adhesion: - Wetting is the ability of a liquid to come over solid surface = Water has a high wetting ability - Viscosity is the property of a liquid that causes it not to flow easily = syrup is liquid with high viscosity and does not flow easily, this is not effective in wetting a surface - Surface characteristic: chemical nature of the tooth ◦ Film thickness: very thin layers should be added to make the junction strong.  Retention – Ability to hold two things firmly together when they will not adhere to each other naturally. ( example: an amalgam filling does not adhere directly to tooth structure) Curing – Setting process of dental material. (cured to harden) Auto-cured/self-cured materials: hardens as result of a chemical reaction of the materials being mixed together. - Material must be mixed and placed withing the manufacture’s working and setting times - Cure by itself. Light-cured Material – does not harden until it has been exposed to a curing light - Allows more flexibility with the working time Dual-cured Material - Some curing takes place as the material is mixed - Final cure does not occur until the material has been exposed to a curing light Restorative and Esthetic Dental Materials o Amalgam (silver fillings) - Powder (different metals) mixed with mercury = soft pliable mixture - Safe, affordable, durable Indications for Dental Amalgam - Primary and Permanent teeth - Stress-bearing areas - Small to moderate cavities to severe destruction of tooth structure - As a foundation for cast-metal, metal-ceramic, and ceramic restorations - When patient commitment to personal oral hygiene is poor - When moisture control is a problem - When cost is a concern to the patient Contraindication to Dental Amalgam - Esthetics are important - Patient has a history of allergy to mercury or other amalgam components - A large restoration is needed, and the cost of other restorative is needed, and the cost of other restorative materials is not significant factor in the treatment decision Components of Amalgam - Mercury - Amalgam Alloy powder (combination of different metal) - Alloy + Mercury = Amalgam, 1:1 ratio known as the Eames technique Alloy Composition - Silver: gives amalgam its strength & color - Tin: for its workability and strength - Copper: for its strength and corrosion resistance ability - Zinc: to suppress oxidation The main differences in the composition and classification of amalgam alloy powders are based on - Alloy particle shape and size - Copper content - Zinc content Application of Amalgam - Supplied as sealed single use capsules (400-600-800 mg of alloy) ◦ Trituration(amalgamation): the process by which the mercury and alloy are mixed together to form the mass of amalgam - In proper mix, amalgam will appear soft, pliable & easily shaped, transferred to the dentist with amalgam carrier ◦ Condensation: Amalgam should be condensed immediately with condenser/ plugger ◦ Carving & Finishing: with hand carving instruments to bring back the natural anatomy of tooth - Occlusion should be checked with the opposing tooth using articulation paper Best management practice for amalgam - Do not contact mercury with your skin - Keep lid closed during trituration(mixing) - Recap capsules immediately after mixing to minimize mercury escaping into the air  - Collect scrap/non-contact amalgam and store in an airtight container, well- sealed, labelled, send to a recycler - Empty Amalgam capsules collected in a container and send to recycler - Disposable Traps: remove & place directly in the container & send to a recycler when full - Reusable traps: Empty the trap in the container, do not rinse with water as this will introduce amalgam to waste stream. Composite Resins (Tooth colored restorations) Contraindication for using composite Resins - Patients with high caries risk - Poor oral hygiene - Abnormal or heavy occlusal stress - Cost issues Composition of composite resins Organic Resin Matrix Inorganic Coupling Agent Pigments – to match tooth color Microfilmed – conventional composite contains the largest filler particles therefore provide the greatest strength, but duller and rougher on the surface Microfilmed – contain inorganic filler that is much smaller and is capable of producing a highly polished finished restoration, used primarily in anterior restoration Hybrid composites – contain both macrofill and microfill particles. Can be polished smooth and has good strength Flowable composite – can be hybrid or nanofilled, in a syringe like device for class V restorations Sealant composites – resembles flowable, used without any tooth preparation Application of Composite Resins Cavity preparation Placement of composite (increment by increment & cute between each layer) Shade selection - Color matching is very important, in daylight or under normal lighting - Patient remove lipstick, make it quick choice  Supplies - Single paste, no need to mix with varying shades - Comes in kits with etching & bonding systems - Bulk filling, decrease the no of increments Polymerization - Auto cure/ light cured (according manufactures instructions) Composition of composite Resins Coupling Agent – Bonds filled to matrix Pigments – to match toot color Glass Ionomers - Excellent, biocompatible, material, adheres chemically with tooth, release fluoride Indication of Glass ionomers - Primary teeth - Final restorations in non-stress areas (root caries & class V) - Sealants - Provisional/temporary restorations - Core build ups Resin Modified - Resin gives the material better strength, greater wear resistance, and an improved esthetic quality. The resin component also allows the material to be light-cured, auto-cured, or both Metal reinforcement - The blend of spherical silver-tin alloy with glass ionomer produces a strong, abrasion-resistant dental material - The glass component provides a desirable balance between working and setting times, together with sustained fluoride release - For core buildups; for repair of fractured cusps and amalgam fillings in class I,II, and V cavities; as a base; and as am abutment for overdentures Fabrication and application  - Supplied as powder and a liquid for cement - Manually mixed together on a treated paper pad, with the powder incorporated into the liquid in several increments - The material must be completely mixed in less than 45 seconds Cautions for placing glass ionomers - Avoid water contamination/contatact with the material - Be aware that when the material’s glossy appearance has disappeared, the setting stages have begun - Protect the matrix band from the material; the material will adhere to a metal band Temporary restorative materials - Maintain and restore function for limited time Functions of Temporary restorative materials: ◦ reduce the sensitivity and discomfort of a tooth ◦ maintain the function and esthetics of a tooth until a permanent restoration can be placed ◦ protect the margins of a prepared tooth that will receive a fixed restoration at later time ◦ prevent shifting of adjacent or opposing teeth caused by an open space IRM ◦ a short-term restoration. ◦ IRM is a reinforced zinc oxide-eugenol composition. ◦ The eugenol has a sedative effect on the pulp, and fillers are added to improve the strength and durability of the material ◦ IRM is supplied as a powder and a liquid, mixed manually on a treated paper pad, or as premeasured capsules that are activated and then triturated. Provisional restorative materials ◦ A provisional restorative material is designed to cover the entire tooth or several teeth for a longer period.  ◦ must withstand biting forces and the daily wear and tear of oral conditions ◦ Acrylic resins are supplied in several applications: as a liquid/powder, in premeasured tubes, and in automix cartridges Tooth whitening materials (bleaching) ◦ are made from a peroxide-based ingredient. ◦ oxygen to enter the enamel and dentin, structure of the tooth is not altered; the tooth is simply made lighter and whiter Indirect restorative materials (CASTINGS) ◦ By a dental laboratory technician Gold noble metal alloys ◦ Gold in its purest form has the ability to resist tarnish and etching when exposed to harsh conditions in the mouth, but it is much too soft for use in cast dental restorations. Tooth colored castings (ceramics) ◦ made of a clay-like material with a glaze that has metallic components to make it durable and able to withstand temperature changes. ◦ most common type: Porcelain fused to metal (PFM) Porcelain ◦ The type of ceramic most often used in dentistry ◦ matches tooth color well & improves the esthetic appearance of anterior teeth. ◦ has the strength of metal. ◦ Porcelain is a good insulator. ◦ The material has a low coefficient of thermal expansion