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Category: Dental Materials

  • Resin Modified Glass Ionomer Cement

    Resin Modified Glass Ionomer Cement

    The two important modifications in the glass ionomer cement (GIC) are the metal and resin-modified glass ionomer cement. The resin-modified glass ionomer cement (RMIG) is developed to combine the advantages of glass ionomer cement and resin composites and at the same time to overcome the disadvantages of these two dental restorative materials. This cement is also referred to as a hybrid ionomer. Due to the fluoride-releasing ability, the glass ionomer cement and resin-modified glass ionomer cement are used in patients with high caries risk and where esthetics is not a major concern.

    Dispensing and Composition of the Resin Glass Ionomer Cement

    The cement-containing capsule is mixed on a device, and the mixed cement is extruded from the capsule into the prepared cavity.


    The powder of this dental cement comprises Fluoroaluminosilicate glass, also known as ion leachable glass, due to its fluoride-releasing properties. The liquid of the cement comprises of polyacid, which reacts with the powder and enables setting by the acid-base reaction, methacrylate resin which enables the setting by polymerization, Hydroxyethyl methacrylate (HEMA), which take part in the polymerization reaction and enable both the resin and acid component to coexist in an aqueous medium, Water is an important component that is required for acid-base reaction to complete, Activators, initiators, and stabilizers are also important ingredients of this dental cement.

    Setting reaction of the Resin Modified Glass Ionomer cement

    Most resin-modified glass ionomer cement is supplied in powder and liquid bottles. The two components are mixed on a special mixing pad supplied with dental cement. Few manufacturers supply this cement in capsules in which the powder and the liquid are enclosed in a capsule. When the powder and liquid are mixed, the acid-base reaction begins immediately. The polymerization reaction starts as soon as sufficient free radicals are available to initiate the reaction.


    The light source used to activate the polymerization of Resin modified glass ionomer cement is similar to that used for dental composites. The light-activated resin-modified glass ionomer cement does not possess a long working time like the resin composite filling material. The possible reasons for this rapid setting and short working time are

    a) The acid-base reaction starts immediately before exposure to the curing light.

    b)  These materials contain chemical initiators and activators which enable the chemically activated polymerization to start before exposure to activating light.

    c) These materials are sensitive to visible light and the setting reaction starts in presence of visible light.

    Most of the resin-modified glass ionomer cement has a light-activated polymerization setting reaction. In comparison, some products used for the cementation of crowns, bridges, and orthodontic appliances are chemically activated.

    Properties of the Resin modified glass ionomer cement

    • The resin-modified glass ionomer cement undergoes expansion when it is in contact with water or moisture and this effect compensates for the initial shrinkage due to the presence of resin.
    • The resin-modified glass ionomer cement is slightly stronger than the conventional glass ionomer cement.
    • This dental cement forms a chemical bond with the tooth structure like the conventional glass ionomer cement.
    • The amount of fluoride release is slightly lower in the resin-modified glass ionomer cement as compared to conventional glass ionomer cement.
    • This restorative material is less soluble and brittle as compared to conventional glass-ionomer dental cement.
    • These materials have a very short setting time as compared to the glass ionomer cement. Therefore, the resin-modified glass ionomer cement should be placed and shaped rapidly after mixing.
    • The presence of resin in this type of glass ionomer cement protects the cement from contamination by moisture. Therefore, protective resin or varnish coatings are not required for these materials and can be finished immediately after setting.

    Clinical Uses of the Cement

    • The resin-modified glass ionomer cement is used as a luting cement for cementation of crown and bridges.
    • This cement is also used for lining purposes in deep cavities for example under amalgam restorations.
    • The resin-modified glass ionomer cement is also used to restore carious and other non-carious lesions at the cervical areas of the tooth.
    • This dental cement is also used for the cementation of orthodontic bands and appliances.

    Resin Modified Glass Ionomer Cement | Dental Cements

  • Metal Reinforced Glass Ionomer Dental Cement

    Metal Reinforced Glass Ionomer Dental Cement

    There are two important modifications in the glass ionomer dental cement: resin-modified glass ionomer cement and the metal-reinforced glass ionomer cement. The aim of developing the metal-reinforced glass ionomer cement is to improve the properties of the glass ionomer cement. This cement is also known as cermet. The main difference with the conventional glass ionomer cement is the addition of metal additives into the glass ionomer cement powder. The liquid is similar to the conventional glass ionomer cement and comprises polyacrylic acid.

    Composition and preparation of Metal reinforced glass ionomer cement

    The metal commonly incorporated into the glass ionomer cement powder is silver. Other metals such as titanium, tin, gold, and palladium have also been incorporated into the modified glass ionomer cement powder.


    The metal-reinforced glass ionomer cement powder is prepared by mixing the glass ionomer cement powder with the metal and forming the pellets under high pressure. These pellets are form around 800 °C, and then these pellets are grind to a fine powder. This fine powder comprises a metal firmly bonded to the glass particles.


    Sometimes, a similar material is developed by manually mixing glass ionomer powder with the amalgam powder in clinical settings. There is no bonding between the glass and the amalgam alloy in this product.

    Dispensing and Setting reaction

    The metal-reinforced glass ionomer cement is mostly supplied in powder and liquid bottles. The powder and liquid are hand-mixed on a mixing pad. Few manufacturers supply metal-reinforced glass ionomer cement in capsules that help in the accurate mixing of the cement. The metal-reinforced glass ionomer cement has a setting reaction similar to the glass ionomer cement.


    The Sodium alumino-silicate glass and metal is the main active ingredient of the cement powder. On mixing with the aqueous solution of polyacrylic acid forms cross-linked polyalkenoate salt. After the metal modified glass ionomer cement placement, the material should be protected from moisture using commercial varnish or Vaseline. Still, it is less moisture sensitive than the glass ionomer cement due to the fast setting reaction.

    Properties of Cement

    • The appearance of the metal-reinforced glass ionomer cement is grey because of the presence of metal particles within the glass ionomer cement powder.
    • The cermet is more radiopaque as compared to conventional glass ionomer cement because of the presence of silver.
    • The metal phase in the dental cermet improves the mechanical properties such as abrasion resistance and brittleness.
    • This modified glass ionomer dental cement maintains the property of chemical adhesion with the enamel and dentin.
    • As compared to the conventional glass ionomer dental cement this modified glass ionomer dental cement has greater values of compressive strength and fatigue limit.
    • The dental cermet has improved erosion resistance as compared to the glass ionomer dental cement.
    • The amount of fluoride released from cermet is less than the conventional glass ionomer cement because part of the glass portion is replaced by metal. Therefore, the antimicrobial and remineralizing potential of cermet is less than the conventional glass ionomer cement.

    Clinical applications of cement

    Because of the color of the cement, it is not suitable for use as an esthetic restoration. It is mostly used to restore posterior teeth for core built-up and as lining material under amalgam restoration. This material is also useful for restoring the occlusal surfaces of primary and permanent molars. This cement only requires lining material such as calcium hydroxide cement when the cavity is deep. After placement, these materials can be finished after a short time (7 to 8 minutes) compared to glass ionomer cement. The carving of the cement can be performed using instruments that are used for the carving of amalgam restorations. While the polishing of the restoration can be performed using a glass ionomer polishing kit.

    Safety and Handling of Metal reinforced glass ionomer cement

     Although no serious hazards are reported with the handling and use of metal modified glass ionomer cement, this material may irritate the skin, irritate the eyes, and damage and irritation the respiratory system. The material should be mixed in a well-ventilated environment, wear protective gloves, eye protection, and face mask to avoid these hazards.

    The material bottles should be closed immediately after use. Rinse with water in case of eye irritation and skin irritation. Clean with soap and rinse with plenty of water. If the irritation persists, then immediately seek medical advice.

    Video lecture | Explanation of Metal-Reinforced Glass Ionomer Cement

  • Glass Ionomer Cement: Dental Cement

    Glass Ionomer Cement: Dental Cement

    The glass ionomer cement (GIC) is available since the early 1970s and it is one of the most popular dental cement to date. It is derived from polycarboxylate and silicate cement. It contains the powder of the silicate cement and liquid of the polycarboxylate cement.

    Dispensing and Composition of Glass Ionomer Cement

    The GIC is available in two forms one is in the powder and liquid bottles and the second and the popular form is in the capsules. The encapsulated cement are popular these days because it offers various advantages as compared to powder and liquid bottles. In the capsule form, the proportion of the powder and liquid is already set by the manufacturer, mixing is quick and clean, less wastage of material, and reduction in the porosity in the final set material.

    Powder of this cement comprises sodium alumino-silicate glass. In addition to the sodium aluminosilicate glass which is the main active ingredient the powder of the GIC also contains 20% Calcium fluoride (CaF) and other minor additives.  The liquid contains an aqueous solution of the polyacrylic acid which is a weak acid as compared to phosphoric acid used in the silicate cement. Sometimes, alternative acids such as an aqueous solution of maleic acid are used in some products. The liquid of the GIC also contains tartaric acid which controls the setting characteristics of this cement. 

    The sodium alumino-silicate glass releases fluoride from the glass ionomer cement matrix and the fluoride release is associated with a reduction in the dental caries susceptibility of the adjacent tooth structure.

    Setting reaction

    The Sodium alumino-silicate glass which is the main active ingredient of the powder on mixing with the aqueous solution of polyacrylic acid forms cross-linked polyalkenoate salt. After placement of the glass ionomer cement, the material should be protected from the moisture using commercial varnish or Vaseline during the initial few hours otherwise the properties of the cement will be adversely affected.   

     After setting the cement matrix can release fluoride into the oral environment. The glass ionomer cement matrix also has the ability of fluoride absorption from the surrounding environment when the fluoride concentration is high for example after tooth brushing with a fluoride toothpaste or after use of fluoridated mouthwash. This process of fluoride release and fluoride absorption back into the glass ionomer cement matrix is referred to as the fluoride recharge mechanism.

    Properties

    The glass ionomer cement forms a chemical bond with the tooth structure and it offers a reasonable match with the natural tooth structure. The glass ionomer cement is a biocompatible dental material with very few adverse reactions. Acid used in this cement (Polyacrylic acid) is a weak acid as compared to phosphoric acid and the acid chains are large and immobile. Therefore, this cement produces only a short and mild pulpal inflammatory reaction.

    The thermal diffusivity value of the glass ionomer cement is closer to that of dentin. The GIC has a thermal insulating effect and helps to protect the dental pulp from the thermal insults. Fluoride ions released by this cement matrix replaces the hydroxyl ions present in the hydroxyapatite structure and form fluorapatite which is more resistant to acid attack. There is recharge or top-up of fluoride in the cement matrix when the concentration of fluoride ions is high in the adjacent environment for example after the use of mouth wash or after brushing teeth with the fluoridated toothpaste. 

    Clinical applications or Uses

    The glass ionomer cement is used to restore cavities where there is less stress for example in class 3 or class 5 cavities. It is a brittle material therefore it is not recommended to use it for restoring the incisal edges or restoring high stress-bearing areas. It is also use to restore cavities prepared with the hand instruments (Atraumatic restorative treatment). Glass ionomer is a material of choice for restoration of the deciduous teeth. This cement is used beneath composite resin or amalgam restorations. The GIC is also used for the cementation of fixed prostheses such as crown and bridges. The cement is also used for the cementation of orthodontic bands.

    Types

    The glass ionomer cement is mainly classified into three types.

    Type 1: The type 1 is mainly used for cementation purposes for example cementation of the crown, bridges, and orthodontic bands.

    Type 2: The type 2 is used for restorative purposes.

    Type 3: The type 3 is used for lining and base applications.

    Modified form of this cement is also known as Cermets and resin-modified glass ionomer cement (RMGIC). We will share the details about these two modifications in our upcoming blog.

    Glass Ionomer Cement | Video Explanation

  • Silicate Cement: A rapid review of the most popular traditional cement

    Silicate Cement: A rapid review of the most popular traditional cement

    The two dental types of cement that have revolutionized dentistry in the past are the zinc polycarboxylate cement and silicate cement. Polycarboxylate cement is the first dental cement that forms a chemical bond with the tooth structure and silicate cement is the first cement that releases fluoride. These two dental types of cement result in the development of modern commonly used dental cement such as the Glass ionomer dental cement having beneficial properties of both the dental cement.

    Dispensing form and Composition of Silicate cement

    The silicate cement is also referred to as Silicophosphate cement in the literature. The cement was supplied as powder and liquid. The powder of the dental cement mainly comprises aluminosilicate glass powder which contains fluoride and liquid comprise of an aqueous solution of phosphoric acid.

    Properties

    The main disadvantage of using silicate dental cement is high solubility. This high solubility leads to loss of anatomical details of the restoration, degradation of cement margins, and discoloration of the restoration. Due to this high solubility of the this cement, the mean survival time of this dental cement is around four years. However, in patients maintaining optimal oral hygiene with minimal consumption of acidic foods and drinks the restoration may survive for twenty years or more.  After the placement of cement into the cavity it is important to protect the cement from moisture as the contamination of cement with moisture further increases the solubility of this dental cement. It is a translucent material and before the introduction of glass ionomer cement and resin composite, it is a material of choice for esthetic restorations. Moreover, it has acidic Ph during the setting of the cement therefore to protect the vitality of the dental pulp lining is essential.  The silicate cement has poor mechanical properties therefore it is used in cavities where is there is low stress such as class 3 cavities. One of the most important properties of silicate cement is the fluoride release. The material can release fluoride over a long period. Therefore, the incidence of dental caries around the silicate cement restorations is very low. The silicate cement is highly hygroscopic (absorbs moisture from the atmosphere) and it would adversely affect the setting time of the dental cement.  

    Clinical Applications

    The silicate dental cement was used as tooth-colored filling material. After the advent of contemporary restorative materials such as glass ionomer cement and composite resin, the use of silicate dental cement declined markedly.

    Silicate Cement | Dental Cement

  • Polycarboxylate cement: An exclusive guide for students

    Polycarboxylate cement: An exclusive guide for students

    The polycarboxylate cement is also known as zinc polycarboxylate dental cement was the first dental cement that exhibits the property of chemical bonding with the enamel and dentin. Before polycarboxylate, the dental cement such as zinc oxide eugenol cement and zinc phosphate cement form the mechanical bond with the tooth structure.

    Dispensing form and Composition of Zinc Polycarboxylate cement

    The polycarboxylate dental cement is supplied as a powder and liquid bottles. The powder of the zinc polycarboxylate dental cement comprises zinc oxide powder which is the key ingredient. The powder also contains a smaller amount of magnesia, tin oxide, bismuth oxide, and alumina. The powder of the zinc polycarboxylate cement in some modified forms contain fluoride salts such as stannous fluoride. The amount of fluoride release from these modified polycarboxylate cement is insignificant as compared to the glass ionomer cement. The liquid of the dental cement comprises an aqueous solution of polyacrylic acid.

    The setting reaction

    The setting reaction of the zinc polycarboxylate dental cement is an acid-base reaction that is between zinc oxide present in the powder and polycarboxylic acid present in the liquid. The reaction results in the formation of a matrix in which the polyacid chains are cross-linked with zinc ions.

    The biocompatibility of the cement is fairly good. This cement is non-injurious to the dental pulp and it forms chemical adhesion with the structure of the tooth. It is used in patients with a history of post-operative sensitivity. This cement is non-injurious to the dental pulp because for two reasons polyacrylic acid is a weak acid as compared to phosphoric acid present in the zinc phosphate cement, secondly, the polyacid chains are too large to penetrate the open dentinal tubules.

    Clinical Applications Polycarboxylate cement

    The following are the uses of zinc polycarboxylate dental cement.

    1. It is used for the cementation of crown, bridges, and inlays.
    2. It is also used as a cavity base material under metallic restorations such as dental amalgam to protect the vitality of the dental pulp. The zinc polycarboxylate dental cement is not used in the deep cavities as a base material and alternative cavity lining materials are used such as Calcium hydroxide cement. Although Polycarboxylate cement is more biocompatible as compared to zinc phosphate cement because of its weak acidic property   but it forms a rubbery consistency during setting. The cement adheres to the stainless steel dental instruments making handling during placement and cleaning of instruments after placement of this dental cement more difficult.
    3. Another use of the zinc polycarboxylate cement is for the cementation of orthodontic bands and the cementation of orthodontic appliances. Now it is less commonly utilized for orthodontic band cementation as new materials with better mechanical properties together with preventive and therapeutic benefits are available such as glass ionomer dental cement (GIC) and resin-modified glass ionomer cement (RMGIC).

    The  Zinc polycarboxylate dental cement is not used for restorative purposes because the cement is opaque and as a result has poor esthetic property, high solubility, and poor mechanical properties.

    Ploycarboxylate Cement | Cements in Dentistry

  • Zinc Phosphate cement: An overview

    Zinc Phosphate cement: An overview

    Zinc phosphate dental cement is one of the oldest dental cement. It is historically used for restorative applications along with the silicate cement. Although new dental materials are now available, this dental cement is still used for restorative applications.

    Dispensing form and Composition of Zinc Phosphate cement

    The zinc phosphate dental cement is supplied in powder and liquid bottles. The cement is also available in capsules in which the powder and liquid are Pre-portioned. The powder component of the dental cement comprises zinc oxide and magnesium oxide. While the liquid component comprises phosphoric acid and water.

    The setting reaction

    The setting reaction is an acid-base reaction. The reaction occurs primarily between zinc oxide, which is the main ingredient of the powder and phosphoric acid, which is the main component of the liquid bottle. This setting reaction results in insoluble zinc phosphate, which is the set form of dental cement.

    The initial setting time of the cement is around 5 minutes. The setting time depends upon numerous factors such as temperature, humidity, and particle size of the dental cement powder. The smaller particle size of the dental cement results in a faster setting of the dental cement.

    Properties

    Zinc phosphate cement forms a weak bond with the tooth structure because it does not form a chemical bond with the tooth structure. The bonding of cement is by mechanical means similar to zinc oxide eugenol dental cement. The thermal conductivity of cement is low. Therefore it is used as a cavity base under metallic restoration such as dental amalgam to protect the vitality of the dental pulp. This cement does not have excellent esthetic properties as the cement is opaque because of the unreacted zinc oxide particles. The new materials, such as composite-based and glass ionomer cement, are now used for luting applications because of ease of use and better mechanical and esthetic properties. In contrast to other dental cement such as glass ionomer cement and zinc oxide eugenol cement, the zinc cement does not have any antimicrobial or therapeutic properties.

    Clinical Applications

    The zinc phosphate cement is used as a cavity liner and base material and has moderate durability. It has traditionally been used as a luting material for crown and bridge cementation. The esthetic properties, as already described, are not excellent, especially when the crown margins are visible. This cement is sometimes used as a temporary filling material.

    Adverse Reactions

    The systemic adverse effects are infrequent with the use of zinc phosphate cement. Local adverse reactions include cytotoxic reactions within the dental pulp. For example, after cementation of the prosthesis in young patients using this cement, it produces cytotoxic reactions due to initial acidic pH during the setting of cement that may lead to pulp necrosis. The young patients are more likely to experience pulp damage because of the open dentinal tubules compared to older patients in which the dentinal tubules become sclerotic.

    Zinc Phosphate Cement | Dental Cement

  • Zinc oxide eugenol cement

    Zinc oxide eugenol cement

    The traditional odor of dental surgeries in the past is due to the use of eugenol or oil of cloves and eugenol containing dental materials such as Zinc oxide eugenol cement, zinc oxide eugenol impression paste.  The eugenol has a strong odor and has bactericidal and pain releveling properties. In this blog, we will provide detailed insight of this dental cement. This cement is also referred to in the literature as Zoe dental cement. Among numerous dental materials, the Zoe Dental cement is classified as a temporary or intermediate restorative material.

    Dispensing and Composition

    The zinc oxide eugenol cement is dispensed in two forms one is the Powder and liquid form and the second is in the two paste forms.  In this cement the powder contains Zinc oxide which is the main active ingredient, another ingredient in the powder is zinc acetate which acts as an accelerator during a setting reaction. In the liquid eugenol is the main active ingredient. Olive oil is present in smaller quantities to control the viscosity of the liquid.

    The two paste system has an advantage over the powder liquid formulations because they are easier to proportion and mix the material especially when the two pastes are available in auto mix dispenser form. The active ingredients of the two paste system are similar to the powder liquid formulations. Water is an important factor in the setting of zinc oxide eugenol. Moisture also accelerates it.

    Setting Reaction of Zinc Oxide Eugenol Cement

    The setting reaction is between zinc oxide and the eugenol that are the two main ingredients of this dental cement. Initially, during the setting reaction, there is the hydrolysis of a zinc oxide powder to zinc hydroxide. The zinc hydroxide than react with the eugenol to form eugenol gel that solidifies in 6 to 10 minutes. The final setting of the zinc oxide eugenol cement occurs within 12 to 24 hours after the placement of the dental cement. The presence of resin, quartz, calcium phosphate, and zinc acetate accelerate the setting of zinc oxide eugenol cement. The external factors that accelerate the setting of this dental cement are moisture, temperature, and humidity.

    Properties

    The compressive strength of ZOE cement is lower than zinc phosphate cement. The reinforced or modified ZOE cement have higher compressive strength as compared to unreinforced ZOE cement. The eugenol leaches out from the set zinc oxide eugenol cement and lessens the pain and inflammation within the dental pulp (obtundent effect). The released unreacted eugenol present in the dental cement matrix is also bactericidal.   However, the leaching of the eugenol from ZOE cement results in the ingress of water into the material and disintegrates this dental cement.  The zinc oxide eugenol cement interferes with the setting and also causes discoloration of resin-based restorative materials.  Therefore, the dental cement should not be used when the final restoration is resin-based.

    Uses of Zinc Oxide Eugenol Cement

    It is used as a cavity base and lining material in deep cavities, for temporary cementation of crown and bridges, temporary filling material, and for periodontal dressing after periodontal surgery.

    Modifications

     Some modifications of the zinc oxide eugenol cement are developed to improve the strength and to reduce the solubility of this dental cement. It is an example in which the eugenol is replaced by carboxylic acid. Replacement of part of eugenol liquid with orthoethoxybenzoic acid (EBA).  Other modifications include reinforced cement in which the alumina is added in the powder and replacement of 20-40% powder with the polymer.

    Adverse Reactions

    This dental cement if placed in the deep cavities may result in the necrosis of the dental pulp. It should be handled with gloves as the eugenol present in the dental cement may cause angular cheilitis, allergic perioral eczema, and contact stomatitis.

    Zinc Oxide Eugenol Cement | Dental Cements

    Zinc oxide eugenol cement
  • Dental Material: An Easy Guide

    Dental Material: An Easy Guide

    If you are a general or a specialist dental practitioner, dental student, or dental researcher it is of paramount importance that you should know about the materials that you are authorized to use in the clinical, laboratory, and research settings. In this blog, we will discuss briefly dental biomaterials, the classification of dental materials, and the ideal properties of dental material.

    The dental material science involves the study of materials composition, physical, chemical, and biological properties and how these dental materials interact with the oral environment in which these materials are placed.

    In other words, dental material science covers a broad range of terminologies, microstructure, and properties of these materials that can be used to predict and describe the performance of the dental materials.

    Classification of Dental Materials

    There are several ways in which dental materials are classified. One of the wide classifications of dental materials is:

    1. Preventive dental materials
    2. Restorative dental materials
    3. Auxiliary dental materials

    Preventive dental materials

    The preventive dental materials include pit and fissure sealants, restorative materials (compomers, glass ionomer cement), toothpaste, gels, mouthwashes, liners, and bases. Some of these dental materials physically prevent the occurrence or progress of the dental disease by modifying the anatomy of favorable sites for microbial growth such as deep pit and fissures. While other materials release therapeutic or preventive agents such as fluoride or chlorhexidine that prevent and inhibit the progress of the disease.

    Restorative dental materials

    The restorative dental materials are used to replace or repair the missing dental hard or soft tissues. These materials include dental cement, dental amalgam, resin-based composites, compomers, ceramics, metal ceramics, cast metals, and denture base polymers. A restorative material can be used for a temporary or provisional purpose (Temporary dental cement such as zinc oxide eugenol cement, temporary crown and bridge polymers) and permanent or long term application (dental cement, inlays, onlays, crown, bridges, dentures, and orthodontic appliances).

    The dental restorative materials are further classified as direct and indirect restorative materials. The direct restorative materials are manipulated in the dental clinic for their final application and include dental Amalgam and dental cement. The indirect restorative materials are prepared for their final application into a dental laboratory by a dental technologist or a technician. The indirect restorative materials include porcelain fused to metal restorations used for crown and bridge construction, metal alloys, and polymers that are used for the construction of complete and partial dentures.

    Auxiliary dental materials

    These materials are used for the fabrication of dental prosthesis or dental appliances. Some of these materials are entirely used in the dental laboratory while some of the materials they link the dental clinic and the dental laboratory.  The dental auxiliary materials include dental impression materials, dental stone, dental plaster, dental waxes, acrylic resin, and finishing and polishing materials. Some of these auxiliary materials may not become part of the final restoration or prosthesis examples of these are dental impression materials, dental stone, and polishing materials.

    The classification of dental materials is not very straight forward as in some cases a preventive dental material can also serve as a restorative dental material, for example, Glass ionomer cement. Similarly, dental polymeric materials have uses both as restorative material and auxiliary material.

    Ideal Properties of Dental Materials

    The ideal dental material should have the following properties.

    1. Biocompatibility: The ideal dental material should be biocompatible it means that the material should perform its desired function without eliciting an immune response.
    2. Bonding: The material should form a permanent bond with the adjacent natural tissues such as tissues of tooth, bone, or soft tissues.
    3. Esthetics: The dental material should match the natural appearance of the replaced tissue such as tooth or oral soft tissues
    4. Chemistry and Structure: Exhibit properties similar to those of the tissues that are being replaced hard tissues of the tooth or oral soft tissues.
    5. Repair or Regeneration: The ideal dental material should be capable of initiating tissue repair or regeneration of the missing or damaged tissues.

    An ideal dental material that exhibits all these properties do not exist as any of these has the properties closer to the structure of the tooth and the other soft and hard tissues of the oral cavity. The material scientists are trying to develop newer materials that exhibit these ideal or closer to these ideal properties.

    Introduction and Classification of Dental Materials