This study mainly focuses on the applications of “smart materials” in the field of dentistry. And this particular field is said to be known as BIO SMART DENTISTRY. Description: “Smart Materials” are materials that can significantly change their properties in response to their environment. These Smart Materials are highly responsive and it is for this reason that they are often called as “responsive materials”. The recent advances in the design of smart materials have created novel opportunities for their applications in bio-medical fields. One of the applications is the dental restoratives. Teeth are constantly subjected to a number of diseases like dental caries. Loss of a tooth structure due to such diseases may be compensated by a number of dental restoratives. Smart materials are used in restoring and preventing dental caries as these materials encounter the carious process and aid in its prevention. Recent developments: The smart materials used in dentistry are the shape memory alloys, ceramics and hollow-core photonic-crystal fibres (PCF). Shape memory alloys are used instead of orthodontic wires while the ceramics like zirconium di oxide are used to build teeth bridges and crystal fibres are used in laser dentistry. The important aspect of smart materials in the field of dentistry is because of its excellent bio compatibility which is the most important property of any bio Material. Conclusion: Due to a rapid progress in this area of science, such smart materials hold a good promise for the future. This paper throws light on smart materials that are used in dentistry and thus the field is said to be known as BIO SMART DENTISTRY.
“Smart materials” are those materials whose properties can be
changed or altered significantly by applying some external stimuli like stress, temperature, moisture, magnetic and electric field, change in pH, etc.,. The use of smart materials and structures is the most promising technology for life time efficiency and reliability in today’s world.
There are a wide range of smart materials that are already in use in a number of fields, some of them are: Piezo electric materials that produce voltage when stress is applied.
Thermo responsive shape memory alloys that can recover any temperature change.
Halo chromic materials that show a significant colour change in response to the change in the acidity.
Photo chromic materials that change their colour, in response to light. Example: light sensitive sunglasses.
“materials that can respond to biological signal can revolutionize medicine”
Biomedical applications of smart materials include:
Delivery of therapeutics
Tissue engineering
Cell culture
Bioseparations
Thermo responsive surfaces
Some of the smart materials used in dentistry include shape memory alloys as orthodontic wires and springs, cercon smart ceramics as dental restoratives SHAPE MEMORY ALLOYS:
Shape memory alloys have a wide use in the field of dentistry because of their exceptional super elasticity, good shape memory and resistance to wear. These materials also have good biocompatibility which is the most essential characteristic of any biomaterial.
The shape memory effect was first observed in copper-zinc and copper-tin alloys by Greninger and Mooradian in the year 1938. These shape memory materials are in radiology, cardiovascular and other medical applications as endovascular stents and tissue connectors. The most commercially important use of these SMAs is the orthodontic applications. The arch wires used as a corrective measure of misaligned teeth for many years were made of stainless steel. As these wires had only limited flexibility and tensile character, they created a great discomfort during the usage. Re-tensioning of these wires for every three or four weeks was necessary for which the patient had to visit the orthodontist very often.
Super elastic wires are used nowadays for these corrective measures owing to their flexibility and resistance. Thus the visits to the orthodontist are reduced significantly. Other than the arch wires there are other orthodontic devices that can move the uneven teeth linearly to correct position by reducing uneven spacing between the teeth.
The movement of these arch wires is only 6mm for 6 months that causes only a minimal discomfort. The superior flexibility, durability, torqueability when compared to stainless steel is the fundamental advantage of these materials thus producing greater ease to use and increased patient comfort.
NITINOL BRACES:
Nickel-titanium alloys (nitinol) are used in case of these braces. The adjustment of any teeth arrangement is due to the remodeling of the bone by the forces exerted by the braces that are used. This force should be minimal and should be of a very narrow range so that it will lead to proper correction of dental malformations. The introduction of SMA braces gave good results due to their corrective forces. The Ni-Ti alloy braces were introduced in 1972 that reduced the length of the orthodontic treatment and reduction of check-ups.
Ni-Ti alloys have a unique combination of properties of shape memory, super elasticity, great workability in martensitic state and resistance to fatigue and corrosion.
The Ni-Ti braces are more comfortable for the patients during installation and also during treatment. Consumption of a very hot or very cold food does not lead to any complications in case of these braces if the austenite and martensite phases are well chosen.
CERAMIC BRACES:
Ceramic braces offer a less-visible alternative to well established traditional metal braces. They blend themselves to the natural colour of the teeth so that they appear more appealing.
The ceramic braces may cause wear to the teeth as these braces are harder than the teeth enamel. So they have the potential to cause a wear or even a severe wear on those teeth that touch against them. Thus the orthodontist should decide that on which all teeth that the braces can be placed. In most cases they are placed on the upper teeth especially on the centre six upper front teeth so that the wear that takes place is less. And also these braces are not placed on the patient’s lower teeth for the fear of creating excessive wear.
Adults very much like to choose ceramics braces because they “blend in” with teeth and they are less noticeable when compared to metals. Ceramic braces are made up of crystalline ceramic. Many adults and a few children also use ceramic braces for there cosmetic advantage.
CERCON-SMART CERAMICS:
In 1995 at ETHZurich
The Zircon based ceramic material is created from one unit with no metal and it is not baked in layers of metals. Thus the product is metal free biocompatible with more strength that helps to resist crack formation. Artificial grey shadows and unsightly dark margins from the underlying metal is no longer a problem with cercon. Cercon Smart Ceramics deliver excellent aesthetics without reservations or compromise whether it is a “front” or “back” teeth, single or multi unit bridges.
A highly stable ceramic oxide which is used in the industrial applications requiring high strength and stability is Zirconium oxide (ZrO2). It has a history as a bio material from 1970’s.
It is also very much useful in non dental applications and in implants. One of the current usages of this material is in total hip replacements. Hip replacements like the dental, show close proximity to vascular and osseous tissues.
Alumina or any other currently available ceramics do not have high fracture toughness and flexural strength as in the case of zirconia. Cercon system offers a good solution to all these needs by taking the advantages of these properties namely strength, toughness, reliability and biocompatibility of zirconium oxide. As cercon ceramics are bioresponsive they are said to be smart materials.
IMPORTANCE OF CERCON SMART CERAMICS:
In dentistry, there has been continuous research and development to find materials suitable for dental prosthesis that are aesthetically acceptable, of sufficient strength and which are perfectly tolerated by the human body. For many years ceramic materials combined with metals have been used in dental restorations, ceramic to achieve the desired aesthetics, metal for strength. A high-tech ceramic, Zirconium Oxide, is now available and has already been pr oven in many extreme situations such as heat shields in the Space Shuttle, brake disks for sports cars and the spherical heads of artificial hip joints. This high-tech ceramic has the potential to give prosthetic care a whole new image, because thanks to Cercon smart ceramics it can now be used in dentistry. With the Cercon system, all-ceramic crowns and bridges of up to four units can be made in the incisal and molar regions. In individual cases, depending on the gap of the bridged teeth, even bridges of up to six units are possible.
SMART COMPOSITES:
Smart composites containing ACP (Amorphous Calcium Phosphate) are also very much useful in bio smart dentistry. Among the most biologically important calcium phosphate ACP is the most soluble one. It also exhibits the property of being rapidly converted into hydroxyapatite (HAP).
When ACP is introduced into specially designed and formulated resin, to make a composite material it will have an extended time release nature to act as a source for calcium and phosphate useful in preventing caries.
One of the basic building blocks of tooth enamel is hydroxyapatite; it is also an inorganic component of dentine. In the case of carious attack hydroxyapatite is removed from the tooth resulting in cavities or white spots.
The exposure of low pH conditions either from bacteria or any other biological organisms releasing, food or acidic beverages result in carious attack. Even if the pH of ACP is neutral or high it remains the same. Only when its pH value gets lower (below or at 5.8) during carious attack ACP gets converted into HAP and precipitates thus replacing HAP lost to the acid.
Thus if the pH in mouth drops below 5.8 these ions will be generated within seconds which ultimately forms a gel. This gel becomes amorphous crystals resulting in calcium and phosphate ions in about 2 minutes.
SMART FIBERS FOR LASER DENTISTRY:
Laser radiation of high- fluency can be easily delivered by Hollow-core photonic-fibers (PCFs) i.e., the laser radiations can easily be snaked through the body using this hollow-core photonic-fibers which are capable of ablating tooth enamel been developed.
Through a hollow-core photonic –fiber, sequences of picoseconds pulses of Nd: YAG laser radiation with a core diameter of approximately 14µm is transmitted and these pulses are focused on the tooth surface to ablate dental tissue.
The same fiber is also used in transmitting emission from plasmas that are produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.
While using these fibers we ought to be very careful because there is a risk factor that in some cases the fiber walls fail and the laser light may escape and harm the healthy tissue.
“Smart materials” are those materials whose properties can be
changed or altered significantly by applying some external stimuli like stress, temperature, moisture, magnetic and electric field, change in pH, etc.,. The use of smart materials and structures is the most promising technology for life time efficiency and reliability in today’s world.
There are a wide range of smart materials that are already in use in a number of fields, some of them are: Piezo electric materials that produce voltage when stress is applied.
Thermo responsive shape memory alloys that can recover any temperature change.
Halo chromic materials that show a significant colour change in response to the change in the acidity.
Photo chromic materials that change their colour, in response to light. Example: light sensitive sunglasses.
“materials that can respond to biological signal can revolutionize medicine”
Biomedical applications of smart materials include:
Delivery of therapeutics
Tissue engineering
Cell culture
Bioseparations
Thermo responsive surfaces
Some of the smart materials used in dentistry include shape memory alloys as orthodontic wires and springs, cercon smart ceramics as dental restoratives SHAPE MEMORY ALLOYS:
Shape memory alloys have a wide use in the field of dentistry because of their exceptional super elasticity, good shape memory and resistance to wear. These materials also have good biocompatibility which is the most essential characteristic of any biomaterial.
The shape memory effect was first observed in copper-zinc and copper-tin alloys by Greninger and Mooradian in the year 1938. These shape memory materials are in radiology, cardiovascular and other medical applications as endovascular stents and tissue connectors. The most commercially important use of these SMAs is the orthodontic applications. The arch wires used as a corrective measure of misaligned teeth for many years were made of stainless steel. As these wires had only limited flexibility and tensile character, they created a great discomfort during the usage. Re-tensioning of these wires for every three or four weeks was necessary for which the patient had to visit the orthodontist very often.
Super elastic wires are used nowadays for these corrective measures owing to their flexibility and resistance. Thus the visits to the orthodontist are reduced significantly. Other than the arch wires there are other orthodontic devices that can move the uneven teeth linearly to correct position by reducing uneven spacing between the teeth.
The movement of these arch wires is only 6mm for 6 months that causes only a minimal discomfort. The superior flexibility, durability, torqueability when compared to stainless steel is the fundamental advantage of these materials thus producing greater ease to use and increased patient comfort.
NITINOL BRACES:
Nickel-titanium alloys (nitinol) are used in case of these braces. The adjustment of any teeth arrangement is due to the remodeling of the bone by the forces exerted by the braces that are used. This force should be minimal and should be of a very narrow range so that it will lead to proper correction of dental malformations. The introduction of SMA braces gave good results due to their corrective forces. The Ni-Ti alloy braces were introduced in 1972 that reduced the length of the orthodontic treatment and reduction of check-ups.
ADVANTAGES OF USING NITINOL BRACES:
Ni-Ti alloys have a unique combination of properties of shape memory, super elasticity, great workability in martensitic state and resistance to fatigue and corrosion.
The Ni-Ti braces are more comfortable for the patients during installation and also during treatment. Consumption of a very hot or very cold food does not lead to any complications in case of these braces if the austenite and martensite phases are well chosen.
CERAMIC BRACES:
Ceramic braces offer a less-visible alternative to well established traditional metal braces. They blend themselves to the natural colour of the teeth so that they appear more appealing.
The ceramic braces may cause wear to the teeth as these braces are harder than the teeth enamel. So they have the potential to cause a wear or even a severe wear on those teeth that touch against them. Thus the orthodontist should decide that on which all teeth that the braces can be placed. In most cases they are placed on the upper teeth especially on the centre six upper front teeth so that the wear that takes place is less. And also these braces are not placed on the patient’s lower teeth for the fear of creating excessive wear.
Adults very much like to choose ceramics braces because they “blend in” with teeth and they are less noticeable when compared to metals. Ceramic braces are made up of crystalline ceramic. Many adults and a few children also use ceramic braces for there cosmetic advantage.
The ceramic braces are translucent in appearance so they blend in with natural tooth colour. This means that unlike traditional stainless steel metal braces, ceramic braces won’t make the smile look “metallic”.
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Smart brackets braces are containing microchip capable of measuring the forces applied to the bracket/tooth line. This braces could significantly reduce the treatment times and to set the non-harmful applied forces.
CERCON-SMART CERAMICS:
In 1995 at ETH
The Zircon based ceramic material is created from one unit with no metal and it is not baked in layers of metals. Thus the product is metal free biocompatible with more strength that helps to resist crack formation. Artificial grey shadows and unsightly dark margins from the underlying metal is no longer a problem with cercon. Cercon Smart Ceramics deliver excellent aesthetics without reservations or compromise whether it is a “front” or “back” teeth, single or multi unit bridges.
A highly stable ceramic oxide which is used in the industrial applications requiring high strength and stability is Zirconium oxide (ZrO2). It has a history as a bio material from 1970’s.
It is also very much useful in non dental applications and in implants. One of the current usages of this material is in total hip replacements. Hip replacements like the dental, show close proximity to vascular and osseous tissues.
Alumina or any other currently available ceramics do not have high fracture toughness and flexural strength as in the case of zirconia. Cercon system offers a good solution to all these needs by taking the advantages of these properties namely strength, toughness, reliability and biocompatibility of zirconium oxide. As cercon ceramics are bioresponsive they are said to be smart materials.
IMPORTANCE OF CERCON SMART CERAMICS:
In dentistry, there has been continuous research and development to find materials suitable for dental prosthesis that are aesthetically acceptable, of sufficient strength and which are perfectly tolerated by the human body. For many years ceramic materials combined with metals have been used in dental restorations, ceramic to achieve the desired aesthetics, metal for strength. A high-tech ceramic, Zirconium Oxide, is now available and has already been pr oven in many extreme situations such as heat shields in the Space Shuttle, brake disks for sports cars and the spherical heads of artificial hip joints. This high-tech ceramic has the potential to give prosthetic care a whole new image, because thanks to Cercon smart ceramics it can now be used in dentistry. With the Cercon system, all-ceramic crowns and bridges of up to four units can be made in the incisal and molar regions. In individual cases, depending on the gap of the bridged teeth, even bridges of up to six units are possible.
SMART COMPOSITES:
Smart composites containing ACP (Amorphous Calcium Phosphate) are also very much useful in bio smart dentistry. Among the most biologically important calcium phosphate ACP is the most soluble one. It also exhibits the property of being rapidly converted into hydroxyapatite (HAP).
When ACP is introduced into specially designed and formulated resin, to make a composite material it will have an extended time release nature to act as a source for calcium and phosphate useful in preventing caries.
One of the basic building blocks of tooth enamel is hydroxyapatite; it is also an inorganic component of dentine. In the case of carious attack hydroxyapatite is removed from the tooth resulting in cavities or white spots.
The exposure of low pH conditions either from bacteria or any other biological organisms releasing, food or acidic beverages result in carious attack. Even if the pH of ACP is neutral or high it remains the same. Only when its pH value gets lower (below or at 5.8) during carious attack ACP gets converted into HAP and precipitates thus replacing HAP lost to the acid.
Thus if the pH in mouth drops below 5.8 these ions will be generated within seconds which ultimately forms a gel. This gel becomes amorphous crystals resulting in calcium and phosphate ions in about 2 minutes.
SMART FIBERS FOR LASER DENTISTRY:
Laser radiation of high- fluency can be easily delivered by Hollow-core photonic-fibers (PCFs) i.e., the laser radiations can easily be snaked through the body using this hollow-core photonic-fibers which are capable of ablating tooth enamel been developed.
Through a hollow-core photonic –fiber, sequences of picoseconds pulses of Nd: YAG laser radiation with a core diameter of approximately 14µm is transmitted and these pulses are focused on the tooth surface to ablate dental tissue.
The same fiber is also used in transmitting emission from plasmas that are produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.
While using these fibers we ought to be very careful because there is a risk factor that in some cases the fiber walls fail and the laser light may escape and harm the healthy tissue.
