BASIC DENTAL MATERIALS PDF

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This article contains Basic Dental Materials PDF for free download. This book has been authored by Manappallil John J. Basic Nature and Properties of Dental Materials Biological Considerations of Basic DENTAL MATERIALS If the pulp is infected, it is removed (pulpectomy) and . Download PDF BASIC DENTAL MATERIALS by Manappallil 4th Edition Free PDF Download of Dental Book. Best Dental Library for Dentist. Get all Dental.


Basic Dental Materials Pdf

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Soldering, Brazing and Welding Abrasion and Polishing Agents Tarnish and Corrosion Dental Implant Materials Appendi x Further Reading I ndex Dentistry and Dental Materials CHAPTER 1 Dental treatment may be divided into 3 phases: This includes educating the patient on how to maintain his oral hygiene through regular brushing, flossing and periodic checkup at the dental office.

Regular brushing with a suitable brush and paste has been shown to be very effective at controlling caries as well as gum periodontal problems. The role of fluorides and fluoride therapy in the control of dental caries has been known to us for a long time. Fluoridation of drinking water and fluoride therapy at the dental office has played a significant role in reducing dental caries especially in children.

Caries often begins in deep fissures in teeth. Fissure sealants is another preventive measure especially in children to prevent caries. Caries involves the actual demineralization and destruction of tooth structure. Our next focus is to arrest the caries process. This involves removing the carious enamel and restoring the cavity with a suitable filling material.

The famous silver filling has been in use for more than a century and is currently the most widely used filling material.

Introduction to dental materials, 4th edition

The silver restoration would certainly look unpleasant if used for the front anterior teeth. Therefore, we would like to restore anterior teeth with an esthetic tooth colored material. Other ways to restore teeth involve the use of gold inlays and ceramic inlays.

As caries progresses, it gets closer to the pulp, which can lead to pain pulpitis and infection of the pulp. If the pulp is only mildly affected, pulp therapy is started using special materials which have a beneficial effect on the pulp.

These materials 2 Basic Dental Materials can be soothing and promote healing by forming a new layer of dentin secondary dentin.

Once the pulp is infected, we have no choice but to remove the pulp pulpectomy. This is the next step. This is known as root canal treatment popularly known as RCT. After removing the pulp, the canal is made sterile and sealed using root canal filling materials.

The root canal treated tooth is fragile and can fracture if not protected with a crown or onlay. Sometimes the tooth structure is so destructed and weakened that a simple restoration would not be sufficient.

In such a case the tooth is covered with a crown or an onlay. Before the discovery of tooth colored crown materials, metallic crowns were given the famous gold tooth. Today dentists are able to provide crowns that are natural looking and pleasing. Many of these structures are processed outside the mouth, in the laboratory. The dental technician uses an accurate model of the teeth to fabricate these restorations. How are these models made?

The dentist makes a negative record of the mouth called an impression.

This is sent to the laboratory where the technician pours a mix of plaster or stone into the impression. When the mix hardens we obtain a model. If the coronal tooth structure is entirely gone or destructed, even a crown would not stay. In this case the dentist has to place a post and core. The part placed into the root canal is known as post and the rest of it is known as the core. The crown is then constructed and cemented on to the core.

Hopeless teeth have to be extracted. After extraction the patient often desires that it be replaced with an artificial tooth. There are many ways of replacing the tooth. Today implants have become very popular. A titanium screw can be implanted into the jaw surgically followed by an artificial crown. The implant is quite an expensive proposition and involves surgery. The next choice is the fixed partial denture bridge. Usually the teeth by the side of the missing tooth is reduced in size prepared in order to receive the bridge.

The bridge is then cemented on to these teeth. If too many teeth are missing, we might have to consider the removable partial denture which replaces the missing teeth but is not fixed in the mouth. It can be removed by the patient for cleaning and hygiene.

The ideal removable partial denture is usually made of a combination of metal and plastic cast partial denture. It can be made entirely of plastic also and is referred to as a treatment partial denture. The final stage is of course when all the teeth have to be replaced. One is of course familiar with the complete denture which is often seen in elderly individuals. These artificial teeth replace the entire dentition and is usually of the removable type fixed complete dentures are also available which are supported and retained by implants.

Manappallil John J. Basic Dental Materials

The teeth used in the denture can be made of acrylic or porcelain. Besides all the materials mentioned above, different specialties in dentistry have their special materials. Some of these are not covered in this book. For example, endodontists use special medicaments to clean and debride the root canal. A variety of root canal sealing pastes and medicaments are also available.

The periodontist uses different types of graft material to restore lost periodontal bone. Unfortunately, not all the materials used in dentistry are within the scope of this book. All dental restorations, whether they be ceramic, plastic or metal are built from atoms. If the reaction of a material and its properties are to be predicted, a basic knowledge of matter is essential.

The difference in form is mainly due to difference in energy. Matter is made up of atoms and for these atoms to be held together there must be a force, e. Thus the gaseous state has more energy than the liquid state. Although the molecules in a gas have a certain amount of mutual attraction, they can diffuse readily and need to be confined in order to keep the gas intact.

Although atoms may also diffuse in the liquid state, their mutual attractions are greater, and energy is required for this separation. As is well known, if the energy of the liquid is decreased by reducing the temperature sufficiently, a second transformation in state occurs and energy is released in the form of heat latent heat of fusion.

This decrease in energy state changes the liquid to a solid or freezes it. The reverse is true when solid is changed to liquid, i.

The temperature at which it occurs is called fusion temperature. These interatomic bonding forces that hold atoms together are cohesive forces. Interatomic bonds may be classified as: Primary bonds or 2. Secondary bonds. Covalent bonds In many chemical compounds, two valence electrons are shared. The hydrogen molecule H 2 is an example of covalent bonding. Another example is methane. The carbon atom has 4 valence electrons that can be stabilized by joining with hydrogen. H Metallic bonds One of the chief characteristics of a metal is its ability to conduct heat and electricity.

Such conduction is due to the mobility of the so called free electrons present in the metals. The outer shield valence electrons can be removed easily from the metallic atom, leaving the balance of the electrons tied to the nucleus, thus forming a positive ion. Secondary Bonds This weaker bond may be said to be more physical than chemical. It is also known as Van Der Waals Forces.

Van Der Waals Forces This is due to the formation of dipole. In a symmetric atom e. This attracts other similar dipoles. A permanent dipole is formed within asymmetric molecules, e.

At temperatures above absolute zero, atoms are 6 Basic Dental Materials in a constant state of vibration. The average amplitude of vibration depends upon the temperature; the higher the temperature the greater will be the kinetic energy and amplitude of the atomic or molecular vibration increases. As the amplitude and internal energy of the atoms increase, the interatomic spacing increases as well.

The gross effect is an expansion known as thermal expansion. If the temperature continues to increase, the interatomic spacing will increase and eventually a change of state will occur e.

Space lattice may be the result of primary or secondary bonds. Crystal structure: A—Simple cubic, B—Body centered cubic, C—Face centered cubic There are 14 possible lattice types of forms, but many of the metals used in dentistry belongs to the cubic system. The simplest cubic space lattice is shown in Figure 2. Their positions are located at the points of intersection of three sets of parallel planes, each set being perpendicular to other planes.

These planes are often referred to as Crystal planes. In noncrystalline structures or amorphous structures, e. There is, however, a tendency for the arrangement of atoms or molecules to be regular, for example, glass is considered to be a noncrystalline solid, yet its atoms bind to form a short range order rather than long range order lattice. In other words, the ordered arrangement of glass is localized with large number of disordered units between the ordered units.

Since such an arrangement is also typical of liquids, such solids are sometimes called supercooled liquids. This interatomic distance depends upon the electrostatic fields of the electrons.

If the atoms come too close to each other, they are repelled from each other by their electrons charges.

On the other hand, forces of attraction keep them from separating. Thus, the atoms are kept together at a position where these forces of repulsion and attraction become equal in magnitude but opposite in direction. This is the normal equilibrium position of the atoms. The normal position of the atoms can be changed by application of mechanical force. For example the interatomic distance can be increased by a force pulling them apart. If the displacing force is measured across a given area it is known as a stress, and the change in dimension is called a strain.

In simple words, stress is the force applied and strain is the resulting change in shape. Theoretically, a stress and a strain exist whenever the interatomic distance is changed from the equilibrium position.

If the stress pulling the atoms apart exceeds the resultant force of attraction, the atoms may separate completely, and the bonds holding them together are broken.

Strain can also occur under compression. However, in this case, the strain produced is limited because when the atoms come closer than their normal interatomic distance, a sudden increase in energy is seen. However, molecules or atoms diffuse in the solid state as well. Diffusion rates depend mainly on the temperature.

The higher the temperature, the greater will be the rate of diffusion. The diffusion rate will, however vary with the atom size, interatomic or intermolecular bonding lattice imperfections. Thus every material has its own diffusion rate.

The diffusion rate in noncrystalline materials may occur at a rapid rate and often may be seen. For example inside a lattice, all the atoms are equally attracted to each other. The interatomic distances are equal, and energy is minimal. However, at the surface of the lattice the energy is greater because there are no atoms on the outside. Hence there is only a force from the inside of the lattice pulling the outermost atoms inwards.

This creates a tension on the outer surface and energy is needed to pull the outermost atoms away. The increase in energy per unit area of surface is referred to as the surface energy or surface tension.

This attraction across the interface for unlike molecules is called adhesion. In summary, the greater the surface energy, the greater will be the capacity for adhesion.

However smooth their surfaces may appear, they are likely to be very rough at the atomic or molecular level. Since these areas form only a small percentage of the total surface, no adhesion takes place. For proper adhesion, the distance between the surface molecules should not be greater than 0.

One method of overcoming this difficulty is to use a fluid that will flow into these irregularities and thus provide contact over a great part of the surface of the solid. For example, when two glass plates are placed one on top of the other, they do not usually adhere. However, if a film of water is placed in between them, it becomes difficult to separate the two plates. To produce adhesion in this manner, the liquid must flow easily over the entire surface and adhere to the solid.

This characteristic is referred to as wetting. The extent to which an adhesive will wet the surface of an adherend may be determined by measuring the contact angle between the adhesive and the adherend. If the forces of adhesion are stronger than the cohesive forces holding the molecules of the adhesive together, the liquid adhesive will spread completely over the surface of the solid, and no angle will be formed e. If the liquid remains as a drop without spreading, the contact angle will be high e.

STRESS When a force acts on body, tending to produce deformation, a resistance is developed within the body to this external force. The internal resistance of the body to the external force is called stress. Stress is equal and opposite in direction to the force external applied. This external force is also known as load.

Since, both applied force and internal resistance stress are distributed over a given area of the body, the stress in a structure is designated as a force per unit area.

Wetting angle; A: Low wetting angle indicates good wettability.

Area over which the force acts is an important factor especially in dental restorations in which areas over which the forces applied often are extremely small. Stress at a constant force is inversely proportional to the area—the smaller the area the larger the stress and vice versa.

The load tends to stretch or elongate a body. Compressive Stress Results when the body is subjected to two sets of forces in the same straight line but directed towards each other. The load tends to or shortens a body. A stress that tends to resist a twisting motion, or a sliding of one portion of a body over another is a shear or shearing stress. STRAIN If the stress internal resistance produced is not sufficient to withstand the external force load the body undergoes a change in shape deformation.

Each type of stress is capable of producing a corresponding deformation in the body.

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The defor- mation resulting from a tension, or pulling force, is an elongation of a body, whereas a compression, or pushing force, causes compression or shortening of the body.

Strain is expressed as change in length per unit length of the body when a stress is applied. Whenever force is applied over a body, complex or multiple stresses are produced. These may be a combination of tensile, shear or compressive stresses. These multiple stresses are called complex stresses.

For example, when a wire is stretched the predominant stress is tensile, but shearing and compressive stresses will also be present because the wire is getting thinner compressed in cross section as it elongates Fig.

If each stress is plotted on a vertical co-ordinate and the corresponding strain change in length is plotted on the horizontal co-ordinate a curve is obtained. This is known as stress- strain curve Fig. It is useful to study some of the mechanical properties.

Thus proportional stress can be defined as the greatest stress that may be produced in a material such that the stress is directly proportional to strain. Stress-strain curve: Thus elastic limit may be defined as the maximum stress that a material will withstand without permanent deformation change in shape. For all practical purposes, the elastic limit and the proportional limit represent the same stress. However, the fundamental concept is different, one describes the elastic behaviour of the material whereas the other deals with proportionality of strain to stress in the structure.

A small amount of permanent strain is tolerable. The limit of tolerable permanent strain is the yield strength. Thus yield strength is defined as the stress at which a material exhibits a specified limiting deviation from proportionality of stress to strain. Determination of Yield Strength How much of permanent deformation can be tolerated? This varies from material to material and is determined by selecting an offset.

An offset is an arbitrary value put for a material. It represents the percent of total permanent deformation that 1 2 Basic Dental Materials is acceptable for the material. In dentistry 0. The yield strength is determined by selecting the desired offset and drawing a line parallel to the linear region of the stress-strain curve Fig.

The point on the stress-strain curve where the offset meets is the yield strength point X. It represents the relative stiffness or rigidity of the material within the elastic range. Since stress is proportional to strain upto the proportional limit , the stress to strain ratio would be constant. Such a material would possess a comparatively high modulus of elasticity.

Application The metal frame of a metal-ceramic bridge should have a high stiffness. If the metal flexes, the porcelain veneer on it might crack or seperate. However, there are instances where a large strain is needed with a moderate or slight stress. For example, in an orthodontic appliance, a spring is often bent a large distance with a small stress. In such a case the material is said to be flexible. The relation between the maximum flexibility, the proportional limit, and the modulus of elasticity may be expressed as: Resilience can be defined as the amount of energy absorbed by a structure when it is stressed not to exceed its proportional limit.

For example when an acrobat falls on a trapeze net, the energy of his fall is absorbed by the resilience of the net, and when this energy is released, the acrobat is again thrown into the air. The resilience of a material is usually measured in terms of its modulus of resilience, which is the amount of energy stored in a body, when one unit volume of a material is stressed to its proportional limit. It is expressed mathematically as: Depending upon the resilience of the object, energy is stored in the body without causing deformation or with deformation.

Impact resistance will be decreased with an increase in the modulus of elasticity, which means that stiffer materials will have less impact resistance. Resilient materials 1 4 Basic Dental Materials will have better impact resistance however, a high stiffness is also necessary to provide rigidity to a material under static loads, e.

Increase in volume leads to an increase in impact resistance. A Charpy type impact tester is used. It has a heavy pendulum which swings down to fracture the specimen.

Another instrument called Izod impact tester can also be used. Application Dentures should have a high impact strength to prevent it from breaking if accidentally dropped by the patient.

Application An elastic impression material deforms as it is removed from the mouth. However, due to its elastic nature it recovers its shape and little permanent deformation occurs. Some materials are more elastic than others. Thus, permanent deformation is higher in hydrocolloids than in elastomers. The three basic types of strength are: Tensile Strength Tensile strength is determined by subjecting a rod, wire or dumbell shaped specimen to a tensile loading a unilateral tension test.

Tensile strength is defined as the maximal stress the structure will withstand before rupture. In this method, a compressive load is placed on the diameter of a short cylindrical specimen. The tensile stress is directly proportional to the load applied as shown in the formula. The strength value is obtained from the cross sectional area and force applied.

Though the load is compressive in nature, the failure is due to complex stresses. Shear Strength Shear strength is the maximum stress that a material can withstand before failure in a shear mode of loading.

It is tested using the punch or pushout method. The formula is as follows: Application Used to study the interface between two materials, e. Transverse or Flexure Strength Transverse strength or modulus of rupture is obtained when a load is applied in the middle of a beam supported at each end.

This test is also called a 3 point bending test 3PB Fig. Area of toughness by three point loading of a beam in stress-strain curve Application Used to test denture base resins and long span bridges.

This type of failure is called fatigue.

Fatigue behaviour is determined by subjecting a material to a cyclic stress of a known value and determining the number of cycles that are required to produce failure. The stresses used in fatigue testing are usually very low. However, the repeated application causes failure. Application Restorations in the mouth are often subjected to cyclic forces of mastication. In order to last, these restorations should be able to resist fatigue.

These materials support a high static load for a long period of time and then fail abruptly. This type of failure occurs only when the materials are stored in a wet environment and this property is related to the effect of water on the highly stressed surface of the material.

It is a property of the material which describes how difficult the material would be to break. Toughness is also measured as the total area under the stress-strain curve Fig. Brittleness is generally considered as the opposite of toughness, e. It will not bend appreciably without breaking. It should not be wrongly understood that a brittle material is lacking in strength.

From the above example of glass we see that its shear strength is low, but its tensile strength is very high. If glass is drawn into a fibre, its tensile strength may be as high as MPA. Application Many dental materials are brittle, e. A metal that can be drawn readily into a wire is said to be ductile. Ductility is dependent on tensile strength.

Ductility decreases as the temperature is raised. Ductility is measured by three common methods: It is not dependent on strength as is ductility. Malleability increases with rise in temperature. Application of Malleability and Ductility Gold is the most ductile and malleable metal. This property enables manufacturers to beat it into thin foils. Silver is second. Among other metals platinum ranks third in ductility and copper ranks third in malleability. There are numerous factors which influence the hardness of a material such as strength, proportional limit, ductility, malleability, etc.

In mineralogy the hardness is described as the ability of a material to resist scratching. In metallurgy and in most other fields, the resistance to indentation is taken as the measure of hardness. There are many surface hardness tests Fig.

Various hardness tests Brinell A hardened steel ball is pressed into the polished surface of a material under a specified load. The load is divided by the area of the surface of the indentation and the quotient is referred to as Brinell Hardness Number BHN.

However, instead of measuring the diameter of the impression, the depth is measured directly by a dial gauge on the instrument. Vickers Hardness Test VHN This is also similar to the Brinell test, however, instead of a steel ball, a diamond in the shape of a square pyramid is used. Although the impression is square instead of round. The load is divided by the area of indentation. The length of the diagonals of the indentation sides of the diamond are measured and averaged.

Applications Vickers test is used in the ADA for dental casting golds. This test is suitable for brittle materials and so is used for measuring hardness of tooth structure. Knoop hardness values is independent of the ductility of the material and values for both exceedingly hard and soft materials can be obtained from this test.

Manappallil John J. (ed.) Basic Dental Materials

The Knoop and Vickers tests are classified as microhardness tests. The Brinell and Rockwell tests are classified as macrohardness tests. The Shore and the Barcol These are less sophisticated tests. They are compact portable units. A metal indenter that is spring loaded is used. The hardness number is based on depth of penetration and is read directly from a gauge.

Applications Used for measuring the hardness of rubber and plastics. Hardness has often been used to indicate the ability of a material to resist abrasion. Applications It is useful for comparing materials in the same class, e. However, it may not be useful for comparing materials of different classes like metals and plastics. If an element is changed from its equilibrium or stable form by either physical or chemical means it tries to come back to its original form. When substances are deformed, internal stresses get trapped because of the displacement of the atoms.

The condition is unstable and the atoms try to return to their original positions. This results in a change in shape or contour in the solid as atoms or molecules rearrange themselves. This change in shape due to release of stresses is known as relaxation. The material is said to warp or distort. Examples Waxes and other thermoplastic materials like compound undergo relaxation after they are manipulated. In dentistry, study of rheology is necessary because many dental materials are liquids at some stage of their use, e.

Other materials appear to be solids but flow over a period of time. Creep Time dependent plastic deformation or change of shape that occurs when a metal is subjected to a constant load near its melting point is known as creep. This may be static or dynamic in nature. Static creep is a time dependent deformation produced in a completely set solid subjected to a constant stress. Dynamic creep produced when the applied stress is fluctuating, such as in fatigue type test.

Importance Dental amalgam, has components with melting points that are slightly above room temperature and the creep produced can be very destructive to the restoration, 2 1 Basic Nature and Properties of Dental Materials e. Flow It is somewhat similar to creep. In dentistry, the term flow is used instead of creep to describe rheology of amorphous substances, e. Although creep or flow may be measured under any type of stress, compression is usually employed for testing of dental materials.

Newtonian Shear stress and shear strain rate can be plotted. An ideal fluid shows a shear strain rate that is proportional to shear stress. This behavior is called Newtonian Fig. Shear diagrams of pseudoplastic, newtonian and dilatant liquids Pseudoplastic If a material viscosity decreases with increase in shear rate it is said to exhibit pseudoplastic behavior, e.

Zinc oxide eugenol cements show reduced viscosity after vigorous mixing. Dental prophy paste is another example. The eye is sensitive to wave lengths from approximately nm violet to nm dark red. The combined intensities of the wavelengths present in a beam of light determine the property called color. In order for an object to be visible, either it must emit light or it must reflect or transmit light falling upon it from an external source.

Objects of dental interest generally transmit light. The incident light is usually polychromatic mixed light of various wavelengths. The spectral distribution of the transmitted or reflected light will resemble that of the incident light although certain wavelengths will be reduced in magnitude.

Cone shaped cells in the retina are responsible for color vision. The eye is most sensitive to light in the green-yellow region and least sensitive at either extremes i. Hue Refers to the basic color of an object, e. This lightness which can be measured independently of the color hue is called value. Chroma represents the degree of saturation of a particular hue color. Chroma cannot exist by itself and is always associated with hue and value. It is a co-ordinate system which can be viewed as a cylinder.

The lines are arranged sequentially around the perimeter of the cylinder, while the chroma increases along a radius from the axis. The value coordinate varies along the length of the cylinder from black at the bottom to neutral grey at the center to white at the top. Daylight, incandescent lamps, and fluorescent lamps are all common sources of light in dental operatory.

Objects that appear to be color matched under one type of light may appear very different under another light source. This phenomenon is called metamerism. These wavelengths between to nm are referred as near ultraviolet.

Natural sunlight, photoflash lamps, certain types of vapor lamps, and the ultraviolet lights used in decorative lighting are all sources containing substantial amounts of near U-V radiation invisible U-V light. The Vita lumin shade guide. Selecting the color using the new Vitapan system. The color is determined in 3 steps. The figure above shows step 1 lightness or darkness. The guide is held along the patients face at arms length.

Step 2 determines the hue basic color. Step 3 determines the chroma saturation This energy that the tooth absorbs is converted into light with larger wavelengths, in which case the tooth actually becomes a light source. The phenomenon is called fluorescence. The emitted light is primarily in nm range, having blue white color. Flourescence makes a definite contribution to the brightness and vital appearance of a human tooth.

Some manufacturers of porcelain include fluorescence matching in their products. The ideal restorative material should match the color of the tooth it restores. In maxillofacial prosthetics the color of the gums, external skin and the eyes have to be duplicated. Clinically in the operatory or dental lab, color selection is usually done by the use of shade guides Figs 2. These are used in much the same way as paint chips are used to select the color for house paint. Biological Considerations of Dental Materials CHAPTER 3 The science of dental materials must include a knowledge and appreciation of certain biological considerations that are associated with selection and use of materials designed for the oral cavity.

Strength and resistance to corrosion are unimportant if the material injures the pulp or soft tissue. The biological characteristics of dental materials cannot be isolated from their physical properties. Biological Requirements of Dental Materials A dental materials should: Don't miss any New Books Sign me up for the newsletter!

John J. Manappallil Edition: We do not own the copyrights of this book. We are Sharing copy of this book available on internet with our reader's for education purpose only. We are not selling any books on this platform. If your PC notify you for Malware or virus than please stop windows defender for a while Restorative Resins, Dental Amalgam, Direct Filling Gold, Dental Cements, Liners and Varnish, Model, Cast and Die Materials, Waxes in Dentistry, Dental Casting Investment Materials, Casting Procedures, Dental Casting Alloys, Dental Ceramics, Wrought Alloys, Soldering, Brazing and Welding, Abrasion and Polishing Agents, Tarnish and Corrosion, Dental Implant Materials.

Download Here http: You just clipped your first slide! Clipping is a handy way to collect important slides you want to go back to later. Now customize the name of a clipboard to store your clips. Visibility Others can see my Clipboard.The load is divided by the area of indentation. Mixing is done with a stainless steel spatula using circular motions until a streak free mix is obtained Manufacturers usually provide such materials in contrasting colors to aid in visually ascertaining completion of mix FIGURE 4.

By measuring reduction in cross-sectional area of fractured ends in comparison to the original area of the wire or rod and the method is called reduction in area method. In dentistry, the term flow is used instead of creep to describe rheology of amorphous substances, e. All comments - are welcome and I would be most happy to respond. This is known as root canal treatment popularly known as RCT. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising.

Difficult to remove if there are severe undercuts. Thus the gaseous state has more energy than the liquid state.