magnet as a dental material--an overview.
Initially, when used as jawiimplants, they are used to help retain the dental prosthesis.
Over the past decade, magnets have been used for orthodontic and dental facial shaping and are trying to evaluate the biological significance of magnets and magnetic fields in clinical applications.
The power they transmit can be directed, and they can exert their power through the mucosa and bones, as well as through the mouth.
The purpose of this article is to give an overall idea of the different types of magnets used in dentistry, their physical properties, their biological safety, and the rough reviews of various reported works by different authors so far.
Magnetic systems are mentioned in the dental literature.
Initially, as Berman and Egen described in 1953, when used as chin implants, they were used to help retain the dental prosthesis (1).
Due to the cost of the and the lack of magnetic properties, the wide use of the in dental repair is prevented.
The introduction of small and powerful permanent rare earth magnets at reasonable prices has made the magnets more and more popular.
Blechman and Smiley first described magnets for orthodontic tooth movement in 1978 (2).
In recent years, magnets and magnets have been considered as alternatives to traditional orthodontic equipment such as elasticity, springs and wires.
The can attract or reject, so it can pull or push the teeth (3)
The advantage of the magnetic system is (4)----
Predictable level of strength-
Better direction force-
No power attenuation for overtime--
They can exert their strength through the mucosa and bone. -
Less patient discomfort and less patientoperation.
Recent studies have shown that magnetic devices not only retain dentures, but also provide an optimized biosafety generation system for orthodontic tooth movement.
While magnets can be very helpful, there are many problems that seriously affect their performance.
A common problem is that the force is significantly reduced if the magnets are not ideally aligned with each other (3).
In addition, the magnets are seriously corroded in the mouth and need a strong coating to protect them.
The whole magnetic system is a joint force system which is beneficial to the risk ratio.
Therefore, the purpose of the discussion is to give an overall picture of the different types of magnets used in dentistry, their physical properties, their biological safety, and the rough reviews of various reported works by different authors so far
Magnet and its physical properties (5)
A is a material that can attract alloys containing iron or iron and is located in the North
When going south freelysutherded.
There is a magnetic field around all magnets.
The magnetic field is called the Arctic from one pole of the and returned to the other pole is called the Antarctic.
The magnetic field causes a change in the medium around the , which is called the flux density.
The unit of flux density is Tesla.
The attraction of iron and the attraction or rejection between the two magnets are due to their pole orientation to each other.
The attraction or rejection of any two magnets is inversely proportional to the square of the distance between them, and the flux density is proportional to the size of the itself.
Aluminum from 1953-nickel-cobalt (Alnico), platinum-
Cobalt and body magnets are used in dentistry, which provide high strength at a reasonable cost.
Their operating temperature is the highest of any commercial and can be protected by plating and easily magnetized after assembly.
They are physically stronger than any other magnetic material.
These magnets are of two forms, the same sex and the opposite sex.
But the problem with these traditional magnets is the risk of demagnetic, not very strong and high cost.
Since the size of these conventional magnets is almost only in the centimeter range, their clinical application is highly limited.
1965, sm-cobalt (SmCo)
Compared with traditional magnets, the developed alloy magnets have excellent magnetic properties.
They can significantly reduce the size and performance improvement of the redesigned product and have almost complete antimagnetic properties.
So it is a permanent .
This is the form of the same sex and also a sintering material with good thermal stability.
Recently developed nd-iron-boron (NdFeB)
The provides the highest magnetic energy per unit volume.
The adhesive material is available in the form of the same sex, and the sintering material is available in the form of the opposite sex.
Although it is sm than sintering-
The working temperature of the cobalt magnetic steel is low and the corrosion resistance is poor, so the protective coating is necessary to prevent corrosion.
Due to the properties of the magnetic crystal to be heterosexual, rare earth magnets can produce high forces relative to their size.
This property allows the crystals to be prioritized in one direction, thereby increasing the magnetic properties.
Therefore, the magnetic force required for dental applications can be obtained with very small magnets.
So these magnets are harmless magnets.
The high mandatory or antimagnetic properties of rare earth magnets are due to their inherent properties and manufacturing processes.
In dentistry, the so-called hard magnetic material is used, which has a general or constant magnetic field.
When magnets are heated to medium temperatures, they suffer irreversible magnetic losses.
In many applications, magnets are embedded in acrylic appliances, and the continuous curing temperature of mma reaches 80 to 90 degrees Celsius, which may result in a large amount of flux loss due to the hot solidification reaction of acrylic acid.
The biological safety of magnets is important to ensure, as far as possible, that any new material for clinical use does not produce any side effects either locally or at the system level.
The biosafety test of the assessed the effect of the static magnetic field and the possible toxic effects of the material or its corrosion products.
Although the most interesting thing is that information about the biological effects of magnets on humans is currently somewhat limited.
However, a number of biological investigations were conducted in various animal species and cell cultures, one of the first studies conducted by Tustsui et al in 1979 (6)
Resistance to sm-was found
The cobalt is similar to the ordinary dental casting alloy, but the addition resistance is relatively low.
Magnets have little toxicity or other negative effects on the tissue. Thus samarium-
Cobalt magnets can be safely used as dental materials if plated or coated.
According to Vardimon and Mueller on 1985 (7)
Electrochemical Properties, corrosion trends and activities of Sm-
Cobalt and nd-iron-
Boron magnets in the oral environment reveal the need to improve the surface coating.
In a detailed study, Kitsugi et al. In 1992 (8)
It is concluded that despite the corrosion activity of nd, iron
Boron is higher than sm-
Cobalt magnets, it is necessary to seal these two magnets for dental use.
In a retrospective study, Drago in 1991 (9)
It is reported that the edges of all magnetic implants used in various clinical repair procedures show evidence of light Ze and corrosion, thus significantly affecting the service life of internal magnets.
Short-term exposure to N human lymphocytes in cell culture studies
Human embryonic fiber cells and LM mouse embryonic fiber cells under the 60 ml magnetic field produced by sm-
The cobalt has no significant effect on growth rate or cell response type (Esformes etal. , 1981)(10).
The boron seems to have no toxic effect on fiber cells (
Sandler and others, 1989)(3)
There is no effect on cell activity in the attraction or rejection magnetic field (
Papadopoulos et al, 1992)(11).
McDonald\'s in 1893 (12)
It was found that in the presence of a static magnetic field generated by SmComagnets, the proliferation and system activity of explosives increased.
The effect of magnetic field on the growth of human cultured cells has no significant effect on DNA synthesis, DNA content, cell shape, surface structure or number of cells (
Sato et al, 1992)(13)
Or activities (
Yamaguchi and others, 1993)(14).
However, the orthodontic magnetic stent that produces a 130 Gaussian magnetic field strength has been shown to affect the oral microbial flora and significantly stimulate the growth of white rosary beads (
Stafollani atal, 1991)(15).
The new has the highest toxicity effect, where the asless marked with the clinically used is the highest, and the smallest marked with the recycledmagnets, so the biological compatibility of the can be maintained in circular use
Bondemark at Al 1994)(16).
The results of these studies suggest a range of effects from no-toxicity to no-toxicity.
Animal Study of platinum implantation
During the six-month period, the cobalt alloy magnets in the dog\'s lower jaw showed the normal order of repair inside and outside the bone in the presence of the magnetized implant (
Toto et al, 1962)(17).
One of the first animal studies to study the role of sm
The cobalt report in the implanted tissue has no adverse effect on blood cells (Cerny, 1979)(18)
There is no abnormality in the tissue around the magnetic implant (Cerny, 1980)(4)
No changes were made to the teeth, periodontal and gum tissue, oral mucosa, or gum bone under a magnetic field of up to 95 ml (Cerny, 1980)(4).
Even in the injection of titanium coating sm-
During the six-month period, the Cobalt Magnet did not show abnormal healing or bone cell activity in the lower jaw of the dog, and there was no significant difference in cell size, shape or content (
Altay et al, 1991)(19).
The pulsed magnetic field and static magnetic field enhance the bone formation and hard tissue density of the asteotommy part of the lower jaw of the Guinea Pig (
Darendeliler, et al, 1997)(20).
In addition, static and pulsed magnetic fields also significantly enhance tooth movement, reducing serum calcium levels, which may be due to an increase in bone formation rate (
Darendeliler, et al, 1995)(21).
Increased white blood cell count in the blood, which may be a reaction to the product of corrosion (
Darendeliler, et al, 1995)(21).
In contrast, a study of the effects of static magnetic fields reported by under-under on bone surface and skin
Aronson and Lindskog, 1991 (22)
, Showed a reversible decrease in the number of epithelial cells in the area where magnets were applied, and a significant increase in the bone absorption area after 3 and 4 weeks.
Bruce and others in 1987 (23)
The results showed that when exposed to a static magnetic field, no histological changes were shown in the bone unit of the fracture, but stronger wound tissue was formed between the bone units.
As mentioned earlier, there is very little research on the biological effects of magnetic fields in humans: in important human studies, the implantation of Platinum
During the 13-month period, the cobalt alloy enters the molar area of the toothless jaw, showing that the bone grows around the (24).
Blechman, 1985 (25)
On 1987, foundstkawata et al found no effect on urine cobalt levels measured at the B-month interval (26)
No significant changes were observed in the concentration of ascor acid, calcium or citric acid.
However, on 1995, Bondemark and others (27)
It was found that the magnetic field had no effect on the blood flow of the upper jaw mucosa and pulpal tissue.
Similarly, Saygili et al. In 1992 (28)
Conclusion: the magnetic field has no adverse effect on the blood flow of oral mucosa.
A study by Bondemark and others in 1998 (29)
No adverse long-term effects were found in human oral mucosa in contact with acrylic coated nd-iron-
The boron is affected by the static magnetic field.
Therefore, the current evidence obtained from biosafety testing indicates that the potential risk of harmful biological effects is negligible.
The clinical application of magnets has been used in dentistry for a variety of purposes, and the most common purpose is to help retain false teeth, oral repair, and orthodontics.
Retention is the basis for the full functioning of the dental restoration.
Retention is usually obtained by one or one combination of movement, mechanical locking, atmospheric pressure and neuromuscular control.
It is possible to obtain permanent, dynamic and positive retention by placing magnets in natural tooth structures or corresponding magnets in abony faults and dental restoration on the chin (30).
This may apply to full mouth dentures (
Implant or cover false teeth)
, Partial dentures, Crown or bridge or surgical or Periodontal splints (30).
Some of the advantages of using magnetic retention and lateral stress on the anchor teeth will be minimized, because the slides freely on adjacent surfaces, the technical procedures involved are simple and quick, the required materials are relatively expensive, and30).
But the disadvantage of using magnetic retention is to create space for magnets, which may involve the development and shedding of teeth, and with the difficulty of keeping requirements and the proper alignment of magnets with each other, a large number of magnets must be added (30).
The treatment and rehabilitation of head and neck cancer patients, and the importance of facial prosthesis, have increased several times.
However, there are still several problems in each construction phase, as well as in the retention of the facial prosthesis.
There are many methods, including mechanical devices and anatomical methods.
Magnets have been effectively used for the retention, maintenance and stability of the combined facial prosthesis.
The in coin form has an advantage over other forms in maxillofacialtips.
The size of the depends on the size of the defect (31).
For the treatment of the anterior opening bite, many treatment options are recommended.
Removable or fixed orthodontic appliances with acrylic bite blocks have recently been used that contain magnets to invade the teeth.
Dellinger on 1986 (32)
Introduced with sm-
A charge-oriented cobalt produces 600-
Back teeth 700 gms.
It is also possible to place small and powerful rare earth magnets behind-
By directly bonding the teeth (33).
Using a to invade the teeth creates a continuous force, but the should be correctly aligned with the desired force direction.
Despite the success of the fixed retainer in stabilizing the front spacing, there are still many undesirable features.
A small magnetic scan is used to retain the middle front teeth that have been gathered together to close the Middle longitudinal crack (34).
In the middle of the gap smallneodymium-iron-
Boron magnets can be bonded with light-cured composites in the distant part of the tooth.
In the process of bonding, the door teeth must be used: acetate-
Organize the stripes so that the magnets are not fixed together.
The advantage of this retention method is that it is easy to maintain oral hygiene or use dental floss, and there is no wire or wall frame near the gums.
The edges and teeth can move completely physically as they are not stitched together.
Unfortunately, this technology has had any long-term tracking, so it cannot be considered as a routine clinical practice at the moment.
The arch expansion and palatal frame bone movement have been in use for many years.
Magnetic appliances used to expand maxilla were tried in experimental animals (35)
It is found that the magnetic expansion produces a controlled force in a predictable range and time, and the expansion speed of the magnetic appliance is slow, so the possibility of fracture of the middle seam is very small.
No attempt has been made to expand the bow on humans, because it is difficult to obtain the proper force in the right direction, and it is difficult to obtain the expansion of the appliance.
Many ways to deal with unerupted or impacted teeth are described.
In many cases, separate exposure is used, or dental accessories are exposed and applied.
A small high-energy can be used to provide traction to help stop the eruption of teeth (36).
Place the boron on the teeth that are not erupting, and incorporate the large into the removable appliance, which can be used to bring the impacted tooth into the arch.
It is easy for the operator, the patient does not have to attach the elasticity or hook to the braces, only needs very little adjustment, and the braces are unlikely to be hit and dropped.
However, there are many limitations to this approach.
If the teeth are far away from the mouth, the force between the magnets can be very small, and if the coating of the is damaged, the theme is the possibility of corrosion of the .
Small magnets can be used to transmit the continuous force of light and close the longitudinal crack without an arch line (37).
Adhesive magnets, gaps, and rotation and angle problems on the lip or upper side of the teeth can be corrected.
However, the difficulty of correctly locating the and the risk of suction if the falling is the main drawback.
Magnets can also be used for edge appliances that bend teeth along the bow line to provide first-class
II traction and extrusion or intrusion into a single tooth: The use of repelled magnetic upper grinding teeth can be moved remotely with improved instruments (38).
The static magnetic field and its biological effects may be the possible mechanism of action to reject the molar expansion .
The can be integrated into the edge bracket to transfer the force (26).
The magnetic bracket is chrome plated sm-
Cobalt magnetic welding at the bottom of the edge bracket can be directly welded to the teeth.
If the distance between the supports is less than 3mm, then the force is passed in the direction of the near and far end.
Magnetic stent is most suitable for treatment-I malocclusion.
Magnets can be used in functional appliances to correct bone chin differences.
Functional orthopedic magnetic apparatus (FOMA)-II (39)& III (40)
Positive therapeutic effects were shown in experimental animals.
First clinical experience of magnetic activator (MAD)
Correct for class-II (41)and class-III(42)
Some cases have been described recently.
It has been found that, in comparison with those appliances that do not have a , incorporating the into the double block reduces the time to produce a vector change and increases the soft tissue change (43).
Magnets are also used to stimulate autologous cartilage graft for the treatment of facial microsomism on the half side, a device known as the PropellantUnilateral magnetic apparatus, PUMA (44).
Conclusion in the field of dentistry, rare earth magnets have been successfully used in the force system of fixing and moving teeth of dentures.
However, magnets have not been used frequently.
Magnets and magnetic systems are better devices both theoretically and academically.
It is worth noting that people can practice in today\'s life.
It needs to be very thorough in magnetic physics.
So the main and only idea of all of these discussions is to review the work of various authors, work with them, enjoy them, and generate systems for better power to think in different ways. REFERENCES (1)
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Ashok Kumar Yena ()
, Ruitu Duggal * Punest Batra ($)()
PG student, associate professor ,($)
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