Dental restoration
Encyclopedia
A dental restoration or dental filling is a dental restorative material used to restore the function, integrity and morphology
Comparative anatomy
Comparative anatomy is the study of similarities and differences in the anatomy of organisms. It is closely related to evolutionary biology and phylogeny .-Description:...

 of missing tooth structure. The structural loss typically results from caries
Dental caries
Dental caries, also known as tooth decay or a cavity, is an irreversible infection usually bacterial in origin that causes demineralization of the hard tissues and destruction of the organic matter of the tooth, usually by production of acid by hydrolysis of the food debris accumulated on the...

 or external trauma. It is also lost intentionally during tooth preparation to improve the aesthetics
Aesthetics
Aesthetics is a branch of philosophy dealing with the nature of beauty, art, and taste, and with the creation and appreciation of beauty. It is more scientifically defined as the study of sensory or sensori-emotional values, sometimes called judgments of sentiment and taste...

 or the physical integrity of the intended restorative material. Dental restoration also refers to the replacement of missing tooth structure that is supported by dental implants.

Dental restorations can be divided into two broad types: direct restorations and indirect restorations. All dental restorations can be further classified by their location and size. A root canal filling is a restorative technique used to fill the space where the dental pulp normally resides.

Tooth preparation

Restoring a tooth to good form and function requires two steps, (1) preparing the tooth for placement of restorative material or materials, and (2) placement of restorative material or materials.

The process of preparation usually involves cutting the tooth with special dental burrs, to make space for the planned restorative materials, and to remove any dental decay or portions of the tooth that are structurally unsound. If permanent restoration can not be carried out immediately after tooth preparation, temporary restoration
Temporary restoration
Temporary restoration is a temporary filling of prepared tooth until permanent restoration is carried out. It is used to cover the prepared part of the tooth, in order to maintain the occlusal space and the contact points, and insulation of the pulpal tissues and maintenance of the periodontal...

 may be performed.

The prepared tooth, ready for placement of restorative materials, is generally called a tooth preparation. Materials used may be gold, amalgam
Amalgam (dentistry)
Amalgam is an alloy containing mercury. The term is commonly used for the amalgam employed as material for dental fillings, which consists of mercury , silver , tin , copper , and other trace metals...

, dental composite
Dental composite
Dental composite resins are types of synthetic resins which are used in dentistry as restorative material or adhesives. Synthetic resins evolved as restorative materials since they were insoluble, aesthetic, insensitive to dehydration, easy to manipulate and reasonably inexpensive...

s, resin-reinforced glass ionomers
Glass ionomer cement
A Glass Ionomer Cement is a dental restorative material used in dentistry for filling teeth and luting cements. These materials are based on the reaction of silicate glass powder and polyalkenoic acid...

, porcelain
Dental porcelain
Dental porcelain is a porcelain used by a dental technician to create biocompatible lifelike crowns, bridges, and veneers for the patient...

 or any number of other materials.

Preparations may be intracoronal or extracoronal.
  • Intracoronal preparations are those preparations which serve to hold restorative material within the confines of the structure of the crown
    Crown (tooth)
    In dentistry, crown refers to the anatomical area of teeth, usually covered by enamel. The crown is usually visible in the mouth after developing below the gingiva and then erupting into place.-References:...

     of a tooth
    Tooth
    Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...

    . Examples include all classes of cavity preparations for composite or amalgam, as well as those for gold and porcelain inlays. Intracoronal preparations are also made as female recipients to receive the male components of Removable partial dentures.
  • Extracoronal preparations are those preparations which serve as a core or base upon which or around which restorative material will be placed to bring the tooth back into a functional or aesthetic structure. Examples include crowns
    Crown (dentistry)
    A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns are often needed when a large cavity threatens the ongoing health of a tooth. They are typically bonded to the tooth using a dental cement. Crowns can be made from many materials, which...

     and onlays, as well as veneer
    Veneer (dentistry)
    In dentistry, a veneer is a thin layer of restorative material placed over a tooth surface, either to improve the aesthetics of a tooth, or to protect a damaged tooth surface. There are two main types of material used to fabricate a veneer, composite and dental porcelain...

    s.


In preparing a tooth for a restoration, a number of considerations will come into play to determine the type and extent of the preparation. The most important factor to consider is decay
Dental caries
Dental caries, also known as tooth decay or a cavity, is an irreversible infection usually bacterial in origin that causes demineralization of the hard tissues and destruction of the organic matter of the tooth, usually by production of acid by hydrolysis of the food debris accumulated on the...

. For the most part, the extent of the decay will define the extent of the preparation, and in turn, the subsequent method and appropriate materials for restoration.

Another consideration is unsupported tooth structure. In the photo at right, unsupported enamel can be seen where the underlying dentin was removed because of infiltrative decay. When preparing the tooth to receive a restoration, unsupported enamel is removed to allow for a more predictable restoration. While enamel is the hardest substance in the human body
Human body
The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs.By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life...

, it is particularly brittle, and unsupported enamel fractures easily.

Direct restorations

This technique involves placing a soft or malleable filling into the prepared tooth and building up the tooth before the material sets hard. The advantage of direct restorations is that they usually set quickly and can be placed in a single procedure. Since the material is required to set while in contact with the tooth, limited energy can be passed to the tooth from the setting process without damaging it. Where strength is required, especially as the fillings become larger, indirect restorations may be the best choice.

Indirect restorations

This technique of fabricating the restoration outside of the mouth using the dental impressions of the prepared tooth. Common indirect restorations include inlays and onlays, crowns
Crown (dentistry)
A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns are often needed when a large cavity threatens the ongoing health of a tooth. They are typically bonded to the tooth using a dental cement. Crowns can be made from many materials, which...

, bridges
Bridge (dentistry)
A bridge, also known as a fixed partial denture, is a dental restoration used to replace a missing tooth by joining permanently to adjacent teeth or dental implants....

, and veneers
Veneer (dentistry)
In dentistry, a veneer is a thin layer of restorative material placed over a tooth surface, either to improve the aesthetics of a tooth, or to protect a damaged tooth surface. There are two main types of material used to fabricate a veneer, composite and dental porcelain...

. Usually a dental technician
Dental technician
A dental technologist is a member of the dental team who, upon presciption from a dental clinician, constructs custom made restorative and dental appliances.There are four major disciplines within dental technology...

 fabricates the indirect restoration from records the dentist has provided of the prepared tooth. The finished restoration is usually bonded permanently with a dental cement
Dental cement
Dental cements are hard, brittle materials formed by mixing powder and liquid together. They are either resin cements or acid-base cements. In the latter the powder is a basic metal oxide or silicate and the liquid is acidic. An acid base reaction occurs with the formation of a metal salt which...

. It is often done in two separate visits to the dentist. Common indirect restorations are done using gold or ceramics.

While the indirect restoration is being prepared, a provisory/temporary restoration
Temporary restoration
Temporary restoration is a temporary filling of prepared tooth until permanent restoration is carried out. It is used to cover the prepared part of the tooth, in order to maintain the occlusal space and the contact points, and insulation of the pulpal tissues and maintenance of the periodontal...

 is sometimes used to cover the prepared part of the tooth, which can help maintain the surrounding dental tissues.

Removable dental prostheses (mainly dentures
Dentures
Dentures are prosthetic devices constructed to replace missing teeth, and which are supported by surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable, however there are many different denture designs, some which rely on bonding or clasping onto teeth or dental...

) are considered by some to be a form of indirect dental restoration, as they are made to replace missing teeth. There are numerous types of precision attachments (also known as combined restorations) to aid removable prosthetic attachment to teeth, including magnets, clips, hooks and implants which could be seen as a form of dental restoration.

The CEREC
CEREC
CEREC is a dental restoration product that allows a dental practitioner to produce an indirect ceramic dental restoration using a variety of computer assisted technologies, including 3D photography and CAD/CAM...

 method is a chairside CAD/CAM
CAD/CAM Dentistry
CAD/CAM dentistry, , is an area of dentistry utilizing CAD/CAM technologies to produce different types of dental restorations, including crowns, crownlays, veneers, inlays and onlays, fixed bridges, dental implant restorations and orthodontic appliances.- History :CAD/CAM usage in dentistry began...

 restorative procedure. An optical impression of the prepared tooth is taken using a camera. Next, the specific software takes the digital picture and converts it into a 3D virtual model on the computer screen. A ceramic block that matches the tooth shade is placed in the milling machine. An all-ceramic, tooth-colored restoration is finished and ready to bond in place.

Another fabrication method is to import STL
STL (file format)
STL is a file format native to the stereolithography CAD software created by 3D Systems. This file format is supported by many other software packages; it is widely used for rapid prototyping and computer-aided manufacturing. STL files describe only the surface geometry of a three dimensional...

 and native dental CAD files into CAD/CAM
CAD/CAM Dentistry
CAD/CAM dentistry, , is an area of dentistry utilizing CAD/CAM technologies to produce different types of dental restorations, including crowns, crownlays, veneers, inlays and onlays, fixed bridges, dental implant restorations and orthodontic appliances.- History :CAD/CAM usage in dentistry began...

 software products that guide the user through the manufacturing process. The software can select the tools, machining sequences and cutting conditions optimized for particular types of materials, such as titanium and zirconium, and for particular prostheses, such as copings and bridges. In some cases, the intricate nature of some implants requires the use of 5-axis machining methods to reach every part of the job.

Restoration classifications

Greene Vardiman Black
Greene Vardiman Black
Greene Vardiman Black , commonly known as G.V. Black, is known as one of the founders of modern dentistry in the United States. He was born near Winchester, Illinois on August 3, 1836 to William and Mary Black. He spent his early life on a farm and quickly developed an interest in the natural world...

 classified the fillings depending on their size and location.
  • Class I Caries affecting pit and fissure, on occlusal, buccal, and lingual surfaces of posterior teeth, and Lingual of anterior teeth.
  • Class II Caries affecting proximal surfaces of molars and premolars.
  • Class III Caries affecting proximal surfaces of centrals, laterals, and cuspids.
  • Class IV Caries affecting proximal including incisal edges of anterior teeth.
  • Class V Caries affecting gingival 1/3 of facial or lingual surfaces of anterior or posterior teeth.
  • Class VI Caries affecting cusp tips of molars, premolars, and cuspids.

Materials used in dental restorations

These metals are mostly used for making crowns, bridges and dentures. Pure titanium could be successfully incorporated into bone. It is biocompatible and stable.

Precious metallic alloys:
  • gold
    Gold
    Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

     (high purity: 99.7%)
  • gold alloys (with high gold content)
  • gold-platina alloy
  • silver-palladium alloy
  • titanium
    Titanium
    Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....



Base metallic alloys:
  • cobalt
    Cobalt
    Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....

    -chromium
    Chromium
    Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...

     alloy
  • nickel
    Nickel
    Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

    -chrome alloy


Amalgam:
  • Silver amalgam
    Amalgam (dentistry)
    Amalgam is an alloy containing mercury. The term is commonly used for the amalgam employed as material for dental fillings, which consists of mercury , silver , tin , copper , and other trace metals...

     (Consist of consists of mercury (50%), silver (~22-32% ), tin (~14%), copper (~8%), and other trace metals)


While banned in many countries due to amalgam leaching tiny amounts of mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

. Amalgam is widely used for direct fillings, mainly for posterior teeth, and completed in single appointment. Cast gold is used for indirect restorations.
Direct Gold:
  • Gold


Although rarely used, due to expense and specialized training requirements, gold foil can be used for direct dental restorations.

Tooth colored

Dental composites are also called white fillings, used in direct fillings. Crowns and in-lays can be made in the laboratory from dental composites. These materials are similar to those used in direct fillings and are tooth coloured. Their strength and durability is not as high as porcelain or metal restorations and they are more prone to wear and discolouration.

Composite resin

Dental composites, also called white fillings, are a group of restorative materials used in dentistry. As with other composite materials, a dental composite typically consists of a resin-based matrix, such as a bisphenol A-glycidyl methacrylate (BISMA) resin like urethane dimethacrylate (UDMA), and an inorganic filler such as silicon dioxide
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...

 silica. Compositions vary widely, with proprietary mixes of resins forming the matrix, as well as engineered filler glasses and glass ceramics. The filler gives the composite wear resistance and translucency. A coupling agent such as silane
Silane
Silane is a toxic, extremely flammable chemical compound with chemical formula SiH4. In 1857, the German chemists and Friedrich Woehler discovered silane among the products formed by the action of hydrochloric acid on aluminum silicide, which they had previously prepared...

 is used to enhance the bond between these two components. An initiator package begins the polymerization reaction of the resins when external energy (light/heat, etc.) is applied. A catalyst package can control its speed. This is not recommended for molars.

After tooth preparation, a thin glue or bonding material layer is applied. Composites are then filled layer by layer and photo-polymerising each using light. At the end the surface will be shaped and polished.

Glass ionomer cement

A glass ionomer cement
Glass ionomer cement
A Glass Ionomer Cement is a dental restorative material used in dentistry for filling teeth and luting cements. These materials are based on the reaction of silicate glass powder and polyalkenoic acid...

 (GIC) is one of a class of materials commonly used in dentistry as filling materials and luting cements. These materials are based on the reaction of silicate glass powder and polyalkeonic acid. These tooth-coloured materials were introduced in 1972 for use as restorative materials for anterior teeth (particularly for eroded areas, Class III and V cavities).

As they bond chemically to dental hard tissues and release fluoride for a relatively long period, modern-day applications of GICs have expanded. The desirable properties of glass ionomer cements make them useful materials in the restoration of carious lesions in low-stress areas such as smooth-surface and small anterior proximal cavities in primary teeth. Results from clinical studies also support the use of conventional glass ionomer restorations in primary molars. They need not be put in layer by layer, like in composite fillings.

Porcelain (ceramics)

Full-porcelain (ceramic) dental materials include porcelain, ceramic or glasslike fillings and crowns (a.k.a jacket crown, as a metal-free option). They are used as in-lays, on-lays, crowns, and aesthetic veneers. A veneer is a very thin shell of porcelain that can replace or cover part of the enamel of the tooth. Full-porcelain (ceramic) restorations are particularly desirable because their color and translucency mimic natural tooth enamel.

Another type is known as porcelain-fused-to-metal, which is used to provide strength to a crown or bridge. These restorations are very strong, durable and resistant to wear, because the combination of porcelain and metal creates a stronger restoration than porcelain used alone.

One of the advantages of computerized dentistry (CAD/CAM technologies) is that it enabled the application of zirconium-oxide (ZrO2). The introduction of this material in restorative and prosthetic dentistry is most likely the decisive step toward the use of full ceramics without limitation. With the exception of zirconium-oxide, existing ceramics systems lack reliable potential for the various indications for bridges without size limitations. Zirconium-oxide with its high strength and comparatively higher fracture toughness seems to buck this trend. With a three-point bending strength exceeding 900 megapascals, zirconium-oxide can be used in virtually every full ceramic prosthetic solution, including bridges, implant supra structures and root dowel pins.

Previous attempts to extend its application to dentistry were thwarted by the fact that this material could not be processed using traditional methods used in dentistry. The arrival of computerized dentistry enables the economically prudent use of zirconium-oxide in such elements as base structures such as copings and bridges and implant supra structures. Special requirements apply to dental materials implanted for longer than a period of thirty days. Several technical requirements include high strength, corrosion resistance and defect-free producibility at a reasonable price.

Ever more stringent requirements are being placed on the aesthetics of teeth. Metals and porcelain are currently the materials of choice for crowns and bridges. The demand for full ceramic solutions, however, continues to grow. Consequently, industry and science are increasingly compelled to develop full ceramic systems. In introducing full ceramic restorations, such as base structures made of sintered ceramics, computerized dentistry plays a key role.

Comparison

  • Composites and Amalgam are used mainly for direct restoration. Composites can be made of color matching the tooth, and surface can be polished after filling.

  • Amalgam fillings expand with age, possibly cracking the tooth and requiring repair and filling replacement. But chance of leakage of filling is less.

  • Composite fillings shrink with age and may pull away from the tooth allowing leakage. If leakage is not noticed early recurrent decay may occur.

  • Fillings have a finite lifespan: an average of 12.8 years for amalgam and 7.8 years for composite resins. Fillings fail because of changes in the filling, tooth or the bond between them. Secondary caries formation can also affect the structural integrity the original filling. Fillings are recommended for small to medium sized restorations.

  • Porcelain and Gold are used for indirect restorations like crowns and partial coverage crowns (onlays). Some types of porcelains are hard, but can cause wear on opposing teeth. They are brittle and are not always recommended for molar
    Molar (tooth)
    Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....

     restorations. A new material called lithium disilicate (ips.emax) is indicated for use on molars for crowns and onlays now because it is fracture resistant compared to other porcelains used for dental restorations.

Experimental

In 2010, researchers reported that they were able to stimulate mineralization of an enamel-like layer of fluorapatite
Fluorapatite
Fluorapatite, often with the alternate spelling of fluoroapatite, is a mineral with the formula Ca53F . Fluorapatite is a hard crystalline solid. Although samples can have various color , the pure mineral is colorless as expected for a material lacking transition metals...

 in vivo.

Restoration of dental implants

Dental implant
Dental implant
A dental implant is a "root" device, usually made of titanium, used in dentistry to support restorations that resemble a tooth or group of teeth to replace missing teeth....

s, are anchors placed in bone, usually made from titanium or titanium alloy. They can support dental restorations which replace missing teeth. Some restorative applications include supporting crowns, bridges, or dental prostheses.

See also

  • Dental restorative materials the materials used for fillings
  • CEREC
    CEREC
    CEREC is a dental restoration product that allows a dental practitioner to produce an indirect ceramic dental restoration using a variety of computer assisted technologies, including 3D photography and CAD/CAM...

  • Fixed prosthodontics
    Fixed prosthodontics
    Fixed prosthodontics in dentistry is a technique used to restore teeth, using fixed restorations , which include crowns, bridges, inlays, onlays, and veneers. Prosthodontists are specialist dentists who have undertaken training recognized by academic institutions in this field...

  • Dental treatment
  • Dental dam
    Dental dam
    A dental dam or rubber dam is a rectangular sheet of latex used in dentistry, in particular endodontic therapy, to reduce contamination, and where dental composite are being placed, due to the need for the area to remain dry during filling placement...

  • Gold teeth
    Gold teeth
    Gold teeth are a form of dental prosthesis. They are sometimes used for cosmetic purposes.-Dental restoration:Dentists have used gold for filling cavities , for crowns, and for other purposes. Gold is malleable, nearly immune to corrosion, and hard enough to form a biting surface that can be used...

  • CAD/CAM Dentistry
    CAD/CAM Dentistry
    CAD/CAM dentistry, , is an area of dentistry utilizing CAD/CAM technologies to produce different types of dental restorations, including crowns, crownlays, veneers, inlays and onlays, fixed bridges, dental implant restorations and orthodontic appliances.- History :CAD/CAM usage in dentistry began...

  • Treatment of knocked-out (avulsed) teeth
    Treatment of knocked-out (avulsed) teeth
    The Treatment of knocked-out teeth consists of replantation, immediately if possible.Immediate replantation insures the best possible prognosis but is not always possible since more serious injuries may be present...

  • Triodent
    Triodent
    Triodent Ltd. is a New Zealand dental manufacturing company based in Katikati, New Zealand.Founded by Dr. Simon McDonald in 2003, it is a New Zealand based manufacturer of dental products....

    V3 Sectional Matrix System for Class II restorations

External links

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