Zinc Oxide–Eugenol – Zinc oxide–eugenol cement ( Fig.21.2 ) contains zinc oxide, rosin, and zinc acetate in the powder. The rosin increases fracture resistance and the zinc acetate is effective in accelerating the reaction rate. The liquid is a preparation of eugenol, which reacts with the powder to form an amorphous chelate of zinc eugenolate.

1. The zinc oxide–eugenol cements are used to provide a sedative effect in deep preparations, but their low compressive strength presents clinical limitations.
2. To strengthen zinc oxide–eugenol cements, acrylic resin and alumina reinforcers have been added.
3. Although these cements are stronger, they remain weaker than the zinc phosphate and glass ionomer cements.

When it was evaluated as a base, zinc oxide–eugenol demonstrated significant microleakage in comparison with glass ionomer cement.4 Because of its sedative effects and years of clinical success, zinc oxide–eugenol remains the material of choice for the pulp chamber filling material following pulpotomies or pulpectomies in the primary dentition.

Zinc oxide–eugenol cements should be used with caution under resin-based composite restorations because the eugenol can inhibit the polymerization of the resin. A glass ionomer cement base may be placed over zinc oxide–eugenol before the placement of resin-based composite in order to avoid polymerization.

Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780323608268000213

What is reinforced zinc oxide-eugenol cement?

Reinforced Zinc Oxide Eugenol Cement This cement features a reinforcing polymer incorporated into the powder. This gives the cement the strength to resist condensation forces and to ensure adequate life when used as a temporary filling. By incorporating the reinforcing agent in the powder instead of the liquid, the mixing properties are excellent.

Features	Benefits
Reinforcing component present in powder	Excellent mixing properties
Radiopaque	Shows clearly under x-ray
Long term temporary restorative	Intermediate solution

What type of zinc oxide-eugenol is used for permanent cementation?

use as dental cement –

In bioceramics: Dental ceramics systems are zinc phosphate and zinc oxide-eugenol (ZOE). Zinc phosphate is typically used for permanent cementation, whereas ZOE is used for temporary cementation. Both can serve as insulating bases to protect tissues from heat or cold passing through highly conductive amalgam restorations. Polycarboxylate cements consist of ceramic powders (zinc oxide

How is zinc oxide used in eugenol cement?

Click on image to view Video Demonstration – Right-click here to download this video, ( Choose the “Save As,” option from the menu.) Separate a sheet from the mixing pad and tape it to the working area to stabilize it. Mix the cement. Carefully and slowly shake the IRM bottle to evenly distribute the powdered contents.

• Place three scoops onto the mixing pad.
• Place four drops of the eugenol next to the powder.
• To mix, incorporate half of the powder into the liquid and fold it in using the stiff side of the mixing spatula and applying heavy force to ensure an even mix.
• Add the remainder of the powder, folding in.
• The final mixture should be putty-like; it should be tacky but malleable, and stiff enough to be properly condensed when placed.

Roll the mixed cement into a long roll and cut it into small pieces using the spatula. Place the cement. For a Class II preparation, place a wedge in the interproximal space; the wedge serves to protect the interdental papilla and keeps it from coming in contact with the cement.

A matrix band may also be necessary in situations in which a significant amount of tooth structure or an entire cusp has been removed. Use the condenser to pick up a piece of the cement and place it into the prepared cavity. If the cement sticks to the instrument, place the instrument into the powder and reapply it to adequately condense the cement into the cavity.

Place the cement in increments and lightly condense, until the entire cavity is filled. Be sure to smear it against the cavosurface margin, creating a seal and simultaneously developing the occlusal anatomy. Carve the cement. Use the Hollenback carver to smooth the interproximal margin and to develop the occlusal embrasure.

• Use the cleoid and beaver tail carvers to develop minimal occlusal anatomy.
• At this time, check the patient’s occlusion using articulating paper and remove any high spots if necessary.
• A damp cotton pellet can be used to help accelerate setting time and to smooth the surface of the cement.
• After the cement has partially set, remove the wedge.

Use of the wedge during placement has also allowed development of a gingival interproximal space for exchange of fluid; after a few days the patient can also use floss to clean this area. Follow Up. When the patient returns for placement of a semi-permanent restoration, a high-speed handpiece is used with lots of water to thin the IRM, which is then fractured away from the cavity walls using hand instruments.

Which oil is used as plasticizer in zinc oxide-eugenol cement?

INTRODUCTION Uses of Dental Cements Classification of Dental Cements ZINC OXIDE EUGENOL CEMENT Composition Setting Reaction of Zinc Oxide Eugenol Cement Manipulation of Zinc Oxide Eugenol (ZOE) Cement Biocompatibility of Zinc Oxide Eugenol Cement Types of ZOE Clinical Uses ZINC PHOSPHATE CEMENT Composition Setting Reaction Manipulation of Cement Mechanical Properties Biocompatibility Clinical Uses ZINC SILICOPHOSPHATE CEMENTS (ZSPC) ZINC POLYCARBOXYLATE CEMENT Composition Manipulation of Zinc Polycarboxylate Cement Setting Reaction Bonding of Polyacrylate Cement to Tooth Structure Mechanical Properties Solubility Biological Considerations Uses of Zinc Polycarboxylate Cement GLASS IONOMER CEMENT Classification of Glass Ionomer Cements Composition of Glass Ionomer Cement Water Settable Glass Ionomer Metal Reinforced Glass Ionomer Cement Resin Modified Glass Ionomer Manipulation of Glass Ionomer Cement Manipulation of Glass ionomer cement – Capsule Form SETTING REACTION Setting Reaction of Autocure Glass Ionomer Cement Setting Reaction of Resin Modified Glass Ionomers Setting Time INDICATIONS OF GLASS IONOMER CEMENT CONTRAINDICATIONS OF GLASS IONOMER CEMENTS PROPERTIES OF GLASS IONOMER CEMENT Physical Properties Biocompatibility Water Sensitivity Adhesion Fluoride Release Esthetics Margin Adaptation and Leakage Radiopacity RESIN CEMENTS Uses Types of Resin Cements Technique for Using Resin Cements INTRODUCTION Dental cements: Dental cements are the materials made from two components, powder and liquid when mixed together form a pastelike or flowable material which hardens to a solid structure. Uses of Dental Cements Dental cement can be used as: • Temporary restoration • Permanent restoration • Temporary luting • Permanent luting • Root canal sealing • Pulp protection – bases – liners/pulp capping agents – varnishes Different uses of cements are determined by: • Composition • Compressive strength • Modulus of elasticity • Film thickness • Solubility • Biocompatibility Classification of Dental Cements Based on Composition i.

• Conventional cement • Zinc phosphate cement • Zinc oxide eugenol cement • Polycarboxylate cement • Glass ionomer cement ii.
• Resin-base cement • Resin cement • Resin modified glass ionomer cement Classification Based on Uses 1.
• Permanent luting cements: • Zinc phosphate 0 Zinc silicophosphate 0 Zinc polycarboxylate cement • Modified ZOE type-II • Glass ionomer cement 2.

Temporary luting cements: • ZOE type I 3. Permanent restoratives: • Silicates • GIC type II 4. Temporary restorative materials: • ZOE (reinforced) type III • GIC type II 5. Bases: A. Under amalgam: • Zinc phosphate • Zinc silicophosphate • Zinc polycarboxylate • Reinforced ZOE (type III) • GIC (type III) • Ca(OH)2 B.

1. Bases under composites: • Zinc polycarboxylate • GIC type III • Ca(OH)2 C.
2. Bases under gold: • Zinc phosphate • Zinc polycarboxylate • GIC (type III) 6.
3. Pulp capping agents: i.
4. Indirect pulp capping agents • Ca(OH)2 • ZOE ii.
5. Direct pulp capping agents • Ca(OH)2 7.
6. Cavity liners i.
7. Under amalgam • Ca(OH)2 ii.

Under composite • Ca(OH)2 • GIC type III • Varnishes ZINC OXIDE EUGENOL CEMENT (FIG.8.1) Zinc oxide eugenol cement is one of the oldest used cement. Since, it has soothing action on pulpal tissues and eugenol has topical anesthetic properties. Hence, it is termed an obtundent material.

Though other cements are also used for temporization, but zinc oxide eugenol cement is used most commonly because zinc oxide eugenol cements are much less irritant to the pulp, less soluble in oral fluids and produce better marginal seal than zinc phosphate. A thick mix of zinc oxide eugenol cement is used for small tooth preparations, but before placing the cement, the prepared surface must be isolated and cleansed.

Zinc oxide eugenol is not used as base material especially when unfilled and filled resins are used as restorative materials because eugenol interferes with polymerization process of resins. In these cases calcium hydroxide is used as base material under resin restoration. Composition a. Powder • Powder Zinc oxide (ZnO)-69.0%-Reactive ingradient • White rosin-29.3%-Reduces brittleness • Zinc stearate-1.0%-Catalyst • Zinc acetate (acts as accelerator) -0.7%Accelerator b. Liquid • Eugenol-85.0%-Reactor • Olive oil-15.0%-Plasticizer.

Setting Reaction of Zinc Oxide Eugenol Cement On mixing powder and liquid, the zinc oxide hydrolysis and subsequent reaction takes place between zinc hydroxide and eugenol to form a chelate, zinc eugenolate. Within this matrix unreacted zinc oxide powder particles are embedded. • First reaction ZnO + H2O – Zn (OH)2 • Second reaction Zn(OH)2 + 2HE – ZnE2 + 21120 • Water is needed for the reaction and it is also a byproduct of the reaction so reaction progresses more rapidly in humid conditions.

• Because zinc eugenolate rapidly hydrolyzes to form free eugenol and zinc hydroxide, it is one of the most soluble cements. To increase the strength of the set material, changes in composition can be made to the powder and liquid. For example, ortho-ethoxybenzoic acid can be added to the liquid or alumina or polymethyl methacrylate powder can be added to the powder. Fig.8.2: Intermediate restorative material; modified zinc oxide eugenol cement Alumina and Ortho-ethoxybenzoic Acid Reinforced Composition a. Powder b. Liquid EBA (Ortho-ethoxybenzoic acid) cement: In this cement, EBA chelates with zinc forming zinc benzoate. Addition of fused quartz, alumina and dicalcium phosphate has also shown to improve mechanical properties of cement. Effect of EBA on Eugenol Cement 1. Increase in compressive and tensile strength.2. More powder can be incorporated to achieve standard consistency.3. Decrease in setting time (if concentration is < 70%).4. EBA does not show adverse effects on pulp. Polymer Reinforced Zinc Oxide a. Powder b. Liquid Polymer reinforced zinc oxide eugenol cement: In this mixture, resin helps in improving strength, smoothness of the mix and decreasing flow, solubility and brittleness of the cement. Manipulation of Zinc Oxide Eugenol (ZOE) Cement • ZOE are available as: (i) powder and liquid system, (ii) paste-paste system.

1. Manipulation of Powder and Liquid System Powder is measured and dispensed with a scoop where as liquid is dispensed as drops on glass slab.
2. Powder is dispensed at one end of glass slab, using cement spatula.
3. The powder is divided in main bulk increment, followed by smaller increments (Figs 8.3 and 8.4).

While dispensing liquid, bottle should be held 90° to the mixing pad. It lets the fluid fall under its own weight. Fig.8.3: Dispensing of zinc oxide eugenol powder and liquid Fig.8.4: Diagrammatic representation of increments of zinc oxide powder • Start the mixing by incorporating half of the powder into the liquid with a heavy folding motion and pressure. • When powder particles are wet with the liquid, add the remaining powder to the mix and continue to use a heavy folding motion to attain a putty consistency. Fig.8.5: Right consistency of ZOE mix • Pick-up a piece of mixed cement and place it into the preparation using a condenser. • If the mix sticks to the condenser, powder the condenser head with cement powder to prevent the instrument from sticking during condensation.

1. Use the condenser head and merge the restoration to the margin of the preparation.
2. For smoothening, clean up and hardening of the restoration, use a wet cotton pellet.
3. For luting consistency, “1 inch” string should be formed when flat surface of spatula is pulled from the mixed cement.
4. Paste-paste System In this two pastes are dispensed in equal lengths on paper pad.

Two pastes have different colors, mixing is done till a homogeneous color is obtained. Working Time and Setting Time These are usually not specified. In general, higher is the P:L, faster the materials sets. Cooling of glass slab slows down the setting reaction (unless the temperature is below the dew point).

Setting time of this cement is long but since water accelerates the setting reaction, it sets faster in mouth than outside. Biocompatibility of Zinc Oxide Eugenol Cement ZOE is the best known obtundent. pH of cement is 7. This makes it least irritating cement. Because of this it is considered most palliative agent to the pulp.

Types of ZOE Type I – Temporary luting Type II – Long-term luting Type III – Temporary restoration Type IV – Intermediate restoration Type I Main features: • Strength of the cement is low so it can be easily removed. • It is used for short-term restorations.

• Free eugenol interferes with the setting of resin bonded composites so carboxylic acids can be used to replace eugenol making it non eugenol cement. Type 11 Main features: • This cement has improved strength and abrasion resistance. • In this cement the part of eugenol liquid substituted by ortho-ethoxybenzoic acid (EBA) and alumina is added to powder.

or • Powder is made up of 20 wt percent to 40 wt percent of fine polymer particles and zinc oxide particles that have been surface treated with carboxylic acid, in this the liquid remains eugenol. Type 111 It is used for temporary restorations which last for a few days to few weeks.

• Type IV It lasts for atleast up to 1 year.
• In this more powder has to be added for achieving better strength.
• Clinical Uses • Base • Temporary cementation • Temporary restoration • Root canal sealer • Liner • Pulp capping agent • Permanent cementation Advantages • Soothing effect on the pulp 0 Good short-term sealing.

Disadvantages • Highly soluble • Low strength • Long setting time • Low compressive strength. ZINC PHOSPHATE CEMENT (FIG.8.6) Fig.8.6: Zinc phosphate cement One of the oldest and most widely used cements, zinc phosphate cement is the standard against which new cements are compared. It was first introduced in 1878 and still used today because of excellent clinical track record.

1. Two Types Type I.• Used for cementation.
2. Specification requires the film thickness of less than 25 microns.
3. Type II: Used as a base and for luting.
4. Specification requires a film thickness between 25 and 40 microns.
5. Composition Powder: The primary ingredients of zinc phosphate cement powder are zinc oxide and magnesium oxide.

• ZnO-90.2%. • MgO-8.2%-condenses the ZnO during the sintering process • Si02-1.4%-acts as an insert filler • Bi203-0.’%-imparts smoothness to the mixed cement • Miscellaneous-(BaO, Ba2SO4, CaO) – 0.1%. All the ingredients are sintered at temperatures between 1000°C and 1400°C into a cake that is subsequently ground into fine powder.

Liquid: The liquid is phosphoric acid and water in the ratio of two parts acid to one part water. It may also contain aluminium phosphate and zinc phosphate. The water content of the liquid is critical and should be controlled to provide a adequate setting time. When the liquid is exposed in open bottle, it absorbs moisture from the air in case of high humidity but in low humidity times it will lose moisture.

In case of very old liquids, the last 25% portion remaining in the bottle should be discarded because it is usually discolored or contaminated. Both aluminium and zinc act as buffers to reduce the reactivity of the powder and liquid. Setting Reaction Phosphoric acid attacks surface of the particles and releases Zn ions into the liquid. Aluminium which already forms a complex with the phosphoric acid reacts with zinc and yields a zincaluminophosphate gel The set cement consists of a zinc phosphate matrix in which unreacted zinc oxide powder particles are embedded. Fig.8.7: Structure of set zinc phosphate cement Manipulation of Cement Manipulation of Zinc Phosphate Cement • Working time – 5 minutes 0 Setting time — 2.5 to 8 minutes • Powder is measured and dispensed with scoop a liquid is dispensed as drops. Cement mixing should be done on cool glass slab with a narrow bladed stainless steel spatula.

• Lower the temperature of the slab during mixing, the longer will be the working time.
• This is advantageous because it allows incorporation of more powder into the liquid which results in greater compressive strength and lower solubility of the final cement.
• Some clinicians prefer to mix the cement using the “frozen slab” technique which greatly extends the working time and allows incorporation of more powder into the liquid.

But this method has disadvantage of incorporating water into the mix. • Since setting reaction is an exothermic type the heat liberated while setting further accelerates the setting rate. So it is very important to dissipate this heat which can be done by a. Fig.8.8A: Diagrammatic representation of increments of zinc phosphate powder Fig.8.8B: Photograph showing increments of zinc phosphate powder • Initial increments are smaller in size so as: – To achieve the slow neutralization of the liquid. – To control the reaction. • Middle increments are larger in size so as to further saturate the liquid to form zinc phosphate.

1. Because of presence of less amount of unreacted acid, this step is not affected by heat released from the reaction.
2. In the end the smaller increments of powder are added so as to achieve optimum consistency • After dividing powder, dispense liquid on the glass slab.
3. While dispensing, the liquid bottle should be held vertical and close to the powder (Fig.8.9).

Repeated opening of the liquid bottle or early dispensing of the liquid prior to mixing should be avoided because evaporation of liquid can result in changes in water/acid ratio which can further result in decrease in pH and an increase in viscosity of the mixed cement. Fig.8.9: While dispensing liquid, the bottle should be held vertical and close to the powder

Which dental cement is the strongest?

PANAVIA™ V5 is the strongest dentin bonding cement we have ever developed.

What is the main component in the liquid form of zinc phosphate cement?

The zinc phosphate cement sets by an acid–base reaction initiated on mixing a powder composed of 90% ZnO and 10% MgO with a liquid that consists of approximately 67% phosphoric acid buffered with aluminium and zinc.

What type of material is zinc oxide eugenol?

Cements – Cements are used in dentistry for various purposes. Some are for cavity lining or bases; others are used as luting agents to lute an indirect restoration to a prepared tooth. Basically, a liner is a thin layer of material (0.5 mm) placed on a prepared tooth to protect it, whereas a base acts as the dentin to withstand the forces applying on it.

It is thicker than the liner and also protects the pulp from thermal and chemical stimulates and galvanic shock. Thus a liner or a base should have good thermally and electrically insulating properties, and not contain irritants. It should set rapidly, exhibit enough strength to resist fracture, and not move or flow easily while the filling material is being placed.

Ideally, linings should be radiopaque so that any caries around the filling material can be seen. The liner or base must not interfere with the setting of the filling material or affect the properties of it. Luting cements share similar properties with linings except for the setting time.

1. There should be enough setting time before the final seating of the restoration.
2. In addition, it should be strong enough to assist retention and have low solubility.
3. Commonly used cements are as follows: • Zinc oxide/eugenol cements are mixtures of zinc oxide (powder) and eugenol (liquid).
4. They are mainly used as a lining or base under amalgam restorations and as temporary luting cements or filling materials.

• Zinc–phosphate cements have zinc oxide as the major component of the powder and phosphoric acid solution as the liquid. They are widely used as luting cements and can also be used as linings with adjustment of the powder/liquid ratio to change the consistency.

However, they may have an irritant effect as a liner in deep cavities. • Calcium hydroxide cements have a low strength and high solubility, and therefore are usually used as linings beneath the base of zinc phosphate cements or other base materials, and are not suitable for luting. Nevertheless, this material does have other properties that make it crucial to dentistry such as the fact that it can be used for pulp capping and root canal sealing.

Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780128012383110335

Why zinc phosphate is used as a base?

Zinc phosphate Zinc phosphate Names Zinc phosphate Identifiers

Y

3D model ()

Y

CID

TD0590000

Y

( EPA )

• InChI=1S/2H3O4P.3Zn/c2*1-5(2,3)4;;;/h2*(H3,1,2,3,4);;;/q;;3*+2/p-6 Y Key: LRXTYHSAJDENHV-UHFFFAOYSA-H Y
• InChI=1/2H3O4P.3Zn/c2*1-5(2,3)4;;;/h2*(H3,1,2,3,4);;;/q;;3*+2/p-6 Key: LRXTYHSAJDENHV-CYFPFDDLAR

,P()(=O).P()()=O

Properties H 4 O 12 P 2 Zn 3 454.11 g·mol −1 Appearance white solid 3.998 g/cm 3 900 °C (1,650 °F; 1,170 K) 158 °C (316 °F; 431 K) insoluble (χ) −141.0·10 −6 cm 3 /mol ( n D ) 1.595 Structure monoclinic Thermochemistry (Δ f H ⦵ 298 ) − 2891.2 ± 3.3 Hazards (fire diamond) Non-flammable Except where otherwise noted, data are given for materials in their (at 25 °C, 100 kPa).

• Y ( Y N ?) Chemical compound Zinc phosphate is an with the formula () 2,
• This white powder is widely used as a resistant coating on surfaces either as part of an process or applied as a (see also ).
• It has largely displaced toxic materials based on lead or chromium, and by 2006 it had become the most commonly used corrosion inhibitor.

Zinc phosphate coats better on a crystalline structure than bare metal, so a seeding agent is often used as a pre-treatment. One common agent is,

Is zinc oxide eugenol cement permanent?

Abstract – Zinc oxide-eugenol (ZOE) cements are widely used as temporary filling materials. However, eugenol has earlier been shown to have a detrimental effect on both resin composites and dentin-bonding systems. The aim of the present in vitro study was to examine whether ZOE cement would also reduce the efficacy of relatively new dentin-bonding systems.

This was done by determination of gap formation around resin composite fillings in dentin cavities and of bond strength of resin composite to enamel and dentin. The tooth surfaces involved were either freshly cut, or had been exposed to a ZOE cement (IRM) or to a non-ZOE cement (Cavit) for 7 d before application of a dentin-bonding system (Gluma CPS or Scotchbond Multi-Purpose Plus) and a resin composite (Z100).

Gap formation was assessed in a light microscope on 20-min-old fillings and expressed as wall-to-wall contraction (the width of the maximum marginal gap in % of the cavity diameter). Bond strength was measured in shear on 1-d-old specimens. The mean values of wall-to-wall contraction were 0.06-0.09% with Scotchbond Multi-Purpose Plus and 0.20-0.24% with Gluma CPS.

The mean values of bond strength to enamel were 22-25 MPa for Scotchbond Multi-Purpose Plus and 20-23 MPa for Gluma CPS, and to dentin were 20-22 MPa for Scotchbond Multi-Purpose Plus and 13-14 MPa for Gluma CPS. The use of Scotchbond Multi-Purpose Plus resulted in higher bond strength to dentin and less wall-to-wall contraction than did Gluma CPS.

No differences were found in either wall-to-wall contraction or in bond strength between the three groups for either dentin-bonding system. Thus, the ZOE cement did not influence the efficacy of two relatively new dentin-bonding systems.

How does zinc oxide eugenol work?

Abstract – Eugenol-containing dental materials are frequently used in clinical dentistry. When zinc oxide-eugenol (ZOE) is applied to a dentinal cavity, small quantities of eugenol diffuse through the dentin to the pulp. Low concentrations of eugenol exert anti-inflammatory and local anesthetic effects on the dental pulp.

What chemical is used as a plasticizer?

The most common plasticisers include esters such as adipates, azelates, citrates, benzoates, ortho-phthalates, terephthalates, sebacates, and trimellitates.

What are the modifications of zinc oxide eugenol cement?

Conclusions: Modifications of a zinc oxide-eugenol temporary cement to change the B/A ratio or to incorporate additives resulted in variations in physical properties. All modified forms of the cement had a film thickness less than 25 microns and a compressive strength below 35 MPa.

Is Surfactant a plasticizer?

Abstract – Formation of solid dispersions as a means to enhance the dissolution rate of poorly soluble Active pharmaceutical ingredients (APIs) typically employs hydrophilic polymer systems and surfactants. While the utility of the surfactant systems in solubilization is well known, the secondary effects of the same on processing and subsequent physical stability of the solid dispersions needs to be studied further.

1. Physical blends of the poorly soluble API and hydrophilic polymers such as PVP-K30, Plasdone-S630, HPMC-E5, HPMCAS, and Eudragit L100 with mass ratio 1:1 were prepared.
2. The surfactants tested in this study included Tween-80, Docusate sodium, Myrj-52, Pluronic-F68 and SLS.
3. Thermal analysis of the API–polymer–surfactant blends suggested that the surfactants caused solvation/plasticization, manifesting in reduction of (i) the melting ( T m ) of API (ii) T g of the polymers and (iii) the combined T g of the solid dispersion formed from quench cooling.

Explanation of these effects of surfactants is attempted based on their physical state (at the temperature of interest), HLB values and similarity of their solubility parameter values with respect to drug–polymer systems. Furthermore, extruded matrices containing different API–polymer (PVP-K30, Plasdone-S630, and HPMC-E5) mixtures prepared with and without surfactants, were produced by feeding the powder blend through a hot-melt extruder.

The melt viscosity of the polymer blends was assessed by torque rheometry using a Haake Rheomix. The physicochemical properties of the extruded API–polymer–surfactant were characterized by differential scanning calorimetry, X-ray diffraction, Raman spectroscopy, and polarized microscopy. The results demonstrated that the glass transition temperature of the carrier polymers decreased as direct result of the surfactants in the extrudate, due to an increase in the chain mobility of polymers.

A decrease in the melt viscosity was seen due to a plasticization of the polymer. The drug release profiles of the extruded solid dispersions containing intra granular surfactants were found to fit the dispersions with extra granularly added surfactants.

Why is dental cement so strong?

The Types of Dental Cements – If you’ve been working with your dentist for some time, your dentists will already choose their preferred dental cement to work with. Some dentists will even have multiple options at their disposal for some instances. If you have a good dentist, they’ll only use the best dental industry offers for tooth care.

Zinc Phosphate: Known as the original cement, zinc phosphate is used for preparing crowns, inlays, onlays, orthodontic appliances, and partial dentures. This cement composition produces high compressive strength, an acceptable film thickness, and high tensile strength that makes it hard to beat. Glass Ionomer: Made with glass powders and polyacrylic acid, the glass ionomer cement is a highly bondable cement that’s great with metal alloys and stainless steel restorations. While glass ionomer cement can also be used with porcelain restorations, it’s most preferred among the majority of dentists for crowns, bridges, posts, and inlays. It provides tensile strength and compressive strength that’s comparable to zinc phosphate. Zinc Polycarboxylate: This variation is the first cement to chemically bond to the tooth’s structure, making it highly valuable for dentists who want truly permanent restorations. It provides little pulp irritation, has a high bonding rate, and can attach to both porcelain and stainless steel restorations. Resin-Modified Glass Ionomer: This glass ionomer cement is enhanced with composite resin, which can be used for build-up restorations and can be used to restore crowns, bridges, orthodontic appliances.

Dental cement has a highly valuable place in dentistry. If you’d like to learn about how dentists use dental cement, contact Dr. Gina Covington at Covington Dental in Hickory, NC, to schedule an appointment.

Which of the following dental cements is the weakest?

Strength – Cements are brittle materials with good compressive but more limited tensile strength. The strongest cements are resin cements, and the weakest is zinc oxide eugenol. Cements used for permanent luting and high-strength bases need good compressive and tensile strength.

As can be seen in Table 13-2, resin-based cement is high in mechanical strength and fracture toughness, and polycarboxylate cement is low in both. Most cements consist of a combination of powder and liquid; their ratio determines many of their properties. The strength of cement is controlled primarily by the amount of powder used in the prepared mix.

In general, an increase in the powder-to-liquid ratio increases the strength of the cement. However, excessive powder or liquid can weaken the cement.

Which compound is used as dental cement?

Cements – Dental cements include zinc phosphate, zinc oxide and eugenol, polycarboxylate (zinc oxide powder mixed with polyacrylic acid) and glass ionomer cements (GICs). Allergic reactions to most dental cements are rare but GICs contain a polyalkenoic acid such as polyacrylic acid plus a fluoride-containing silicate glass (fluoroaluminosilicate) powder, and do occasionally cause reactions.

• Resin-modified glass ionomer cements (RMGICs) usually contain HEMA (hydrophilic monomer) plus a fluoride-containing glass and polyacrylic acid.
• Tri-cure GICs also incorporate a chemical curing tertiary amine-peroxide reaction to polymerize the methacrylate, along with the photo-initiation and acid–base ionic reaction.

These resins may cause reactions. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780702054013000291

What is the main component of cement?

Chemical composition Portland cement is made up of four main compounds: tricalcium silicate (3CaO · SiO 2 ), dicalcium silicate (2CaO · SiO 2 ), tricalcium aluminate (3CaO · Al 2 O 3 ), and a tetra-calcium aluminoferrite (4CaO · Al 2 O 3 Fe 2 O 3 ).

How strong is zinc phosphate?

Abstract – An in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars which were divided into three groups of 10 teeth in each group.

Then the teeth were stored in artificial saliva and incubated at 37°C for 24 h. A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded using Instron recorder and analyzed for statistical significance. The surface area of crown was measured by graphical method.

The retentive strength was expressed in terms of kg/cm 2, which was calculated by the equation load divided by area. Retentive strengths of zinc phosphate (ranged from a minimum of 16.93 to amaximum of 28.13 kg/cm 2 with mean of 21.28 kg/cm 2 ) and glass ionomer cement (minimum of 13.69 – 28.15 kg/cm 2 with mean of 20.69 kg/cm 2 ) were greater than that of polycarboxylate cement (minimum of 13.26 – 22.69 kg/cm 2 with mean of 16.79 kg/cm 2 ).

Which component of the liquid in zinc phosphate cement is most essential for the setting reaction?

Abstract – The liquid of zinc phosphate dental cement contains Al3+ and Zn2+, and these ions effect greatly on the setting reaction of the cement. When zinc oxide powder is mixed with this cement liquid, reaction products in the set cement are amorphous and not made sure by X-ray diffraction.

What are the advantages of reinforced zinc oxide-eugenol cements?

Abstract – Zinc oxide-eugenol cements are considerably better tolerated by tissue than other dental materials. As they alleviate pain and are bacteriostatic and antiseptic, they are well tolerated by patients. The cements are good insulators and possess better sealing properties than zinc phosphate cements.

Because of their poor mechanic properties, the conventional zinc oxide-eugenol cements are mainly used as temporary fixing contents and filling materials, for gingival dressings and together with filling materials as impression materials. Recently, reinforced zinc oxide-eugenol cements and cements containing ethoxy benzoic acid (EBA) have been developed.

These new cements have considerably better mechanic properties and are therefore used for cement bases, indirect capping, long-term temporary fillings and in selected cases as definite fixing cements.

How long does zinc oxide-eugenol cement last?

Properties – ZOE cements are considered biocompatible because of their neutral pH, antibacterial action, and anodyne effect on hyperemic pulpal tissue. Their antibacterial activity in vitro was shown to be more efficient than those displayed by conventional and resin-modified glass ionomers.

1. That characteristic associated with a good marginal seal favors the recovery of the pulp.
2. Eugenol released from the salt matrix may contribute to pain relief in preparations with little remaining dentin thickness.
3. However, in high concentrations or when placed directly in contact with connective tissue, it may increase the inflammatory response because of its cytotoxicity.

The low strength displayed by ZOE cements makes them a suitable material for temporary cementation. The ISO 3107 standard (2004) establishes a maximum 24-hour compressive strength of 35 MPa for type 1 materials (i.e., intended for temporary cementation).

• An important aspect related to the mechanical behavior of ZOE cements is that their properties are very sensitive to temperature.
• For example, compressive strength at 37°C may represent only 20% of what was found at 23°C.
• EBA-eugenol cements can be several times stronger than the basic formulation (72 MPa vs.26 MPa, in compression at room temperature).

EBA-alumina cements can present 20% higher strength compared to EBA-eugenol materials. Even though these values are above the minimum compressive strength required for type 2 materials (i.e., permanent luting cements) of 35 MPa, both reinforced ZOE cements are the weakest among luting agents used for permanent cementation.

• The elastic modulus of EBA-eugenol cements (determined at room temperature) is 3 GPa.
• ZOE cements present increased plasticity even after set and flow under load.
• Plastic strain at fracture was shown to be above 15% at 37°C, against a maximum value of 4% presented by other acid-base and resin cements.

Creep behavior may explain the good marginal seal achieved with these materials, even considering their setting shrinkage. Linear shrinkage values of wet samples after 24 hours were shown to be 0.31% for the basic ZOE formulation, 0.38% for EBA-eugenol, and 0.12% for EBA-eugenol/alumina cements.

Film thickness measured according to the ISO standard ranges between 16 and 28 μm for EBA/alumina materials; therefore it is close to the maximum value allowed. Simulated crowns cemented with a basic formulation and EBA-eugenol cement showed similar film thicknesses at the occlusal surface (20 to 25 μm), whereas for the EBA-alumina cement, film thickness was higher (57 μm).

The zinc-eugenolate matrix chelate is very unstable in water. Its hydrolysis forms eugenol and zinc hydroxide, releasing the zinc oxide particles exposed in the process. In vitro studies showed that zinc 2-ethoxybenzoate matrix formed in EBA-eugenol cements is even more prone to hydrolysis than the zinc eugenolate.

1. In vivo, material loss after 6 months was three to seven times higher for an EBA-alumina cement compared to other acid-base cements.
2. Clinically, fixed prostheses cemented with EBA-alumina cement showed a success rate of 92% after 2.5 years, whereas for zinc polycarboxylate, it was 95%.
3. Zinc phosphate, for many decades the “gold standard” for permanent luting agents, showed a success rate of 98%.

The inhibitory effect of methoxyphenols such as eugenol on the polymerization of methacrylate resins is of clinical importance. Eugenol is considered a free-radical scavenger, due to the presence of the allyl group in its structure acting as a degradative chain-transfer agent (i.e., when activated, it preferably undergoes primary radical termination, rather than propagation).

Temporary cements containing eugenol may negatively affect the polymerization of methyl methacrylate used in provisional restorations. If the final restoration will be bonded to the prepared tooth, the polymerization of both the adhesive system and the resin cement may be inhibited, increasing the risk of debonding, or even fracture in case of low-strength, silica-based ceramics or indirect composite restorations.

In fact, in ZOE cement/composite interfaces, composite mechanical properties were reduced up to a 100 μm away from the interface, which may be relevant if the resin cement is applied to a eugenol-contaminated surface. However, several in vitro investigations have shown that bond strength to dentin is not adversely affected if the surface is thoroughly cleaned prior to adhesive application.

Is zinc oxide-eugenol cement permanent?

Abstract – Zinc oxide-eugenol (ZOE) cements are widely used as temporary filling materials. However, eugenol has earlier been shown to have a detrimental effect on both resin composites and dentin-bonding systems. The aim of the present in vitro study was to examine whether ZOE cement would also reduce the efficacy of relatively new dentin-bonding systems.

• This was done by determination of gap formation around resin composite fillings in dentin cavities and of bond strength of resin composite to enamel and dentin.
• The tooth surfaces involved were either freshly cut, or had been exposed to a ZOE cement (IRM) or to a non-ZOE cement (Cavit) for 7 d before application of a dentin-bonding system (Gluma CPS or Scotchbond Multi-Purpose Plus) and a resin composite (Z100).

Gap formation was assessed in a light microscope on 20-min-old fillings and expressed as wall-to-wall contraction (the width of the maximum marginal gap in % of the cavity diameter). Bond strength was measured in shear on 1-d-old specimens. The mean values of wall-to-wall contraction were 0.06-0.09% with Scotchbond Multi-Purpose Plus and 0.20-0.24% with Gluma CPS.

• The mean values of bond strength to enamel were 22-25 MPa for Scotchbond Multi-Purpose Plus and 20-23 MPa for Gluma CPS, and to dentin were 20-22 MPa for Scotchbond Multi-Purpose Plus and 13-14 MPa for Gluma CPS.
• The use of Scotchbond Multi-Purpose Plus resulted in higher bond strength to dentin and less wall-to-wall contraction than did Gluma CPS.

No differences were found in either wall-to-wall contraction or in bond strength between the three groups for either dentin-bonding system. Thus, the ZOE cement did not influence the efficacy of two relatively new dentin-bonding systems.