|Year : 2016 | Volume
| Issue : 1 | Page : 20-24
The method and device for thermoregulation and optimization of dental material's quality and working time
Sajjad Ashnagar1, Nastaran Chokhachi Zadeh Moghadam2, Mina Falah3
1 Department of Periodontics and Oral Medicine, Michigan School of Dentistry, Ann Arbor, USA
2 Students Scientific Research Center, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
3 Department of Bio informatics and Medical Informatics, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
|Date of Web Publication||24-Feb-2016|
Nastaran Chokhachi Zadeh Moghadam
School of Dentistry, Tehran University of Medical Sciences, North Kargar Street, Amir Abad, Tehran
Source of Support: None, Conflict of Interest: None
Introduction: No one can cast a shadow of doubt on the fact that temperature is a key element in dentistry. Temperature control enable dentists in a variety of clinical fields to perform more convenient. Frozen slab is a known method for manipulating temperature before mixing cements. But lack of precise temperature and infection control is bolded. Clinical innovation: The present apparatus determines a method for temperature control in routine dentistry tasks; namely restorative dentistry, prosthesis and even injections. This device is capable of whether heating or cooling materials using low voltage electricity. Peltier or thermoelectric effect is the mechanism behind this device. As operator sets a temperature, device would provide it via metal pads arranged on it in seconds. Discussion: Other common methods used in dentistry have some issues regarding power usage, infection control, size and etc. However, this device is small, cost effective, simple to use and has fast action. Infection control can be actively be maintained with it. This device is a promising alternative for this purpose. Present manuscript summarizes device properties and its potential utilities in dentistry.
Keywords: Dental material, Peltier effect, setting time, thermoregulation, working time
|How to cite this article:|
Ashnagar S, Moghadam NZ, Falah M. The method and device for thermoregulation and optimization of dental material's quality and working time. Dent Hypotheses 2016;7:20-4
|How to cite this URL:|
Ashnagar S, Moghadam NZ, Falah M. The method and device for thermoregulation and optimization of dental material's quality and working time. Dent Hypotheses [serial online] 2016 [cited 2019 Jun 17];7:20-4. Available from: http://www.dentalhypotheses.com/text.asp?2016/7/1/20/177410
| Introduction|| |
The energy changes kinetics of particles of matters. As higher temperature encompasses more energy, chemical reaction might be hastened or delayed with the variance in temperature. The working and setting time of some dental materials are affected by variations in room temperature. , In fact, the reaction rate and consequently the setting rate of these materials greatly differ based on the temperature of the mixing slab.
In particular, it is known that even relatively moderate variation in temperature greatly affects the setting rate and working and setting times of the mixture. For instance, 15°C more or 15°C less give rise to a reduction or an acceleration of 100% setting rate of the mentioned material. The specifications established by the American Dental Association are clear about the importance of the temperature control during dental materials manipulation. 
Control of heat generation and achieving sufficient working time can theoretically be accomplished by three methods as follows: Decreasing the powder/liquid proportion, decreasing the rate of adding powder to the liquid, and cooling of the mixing slab. 
Presently, the main method for controlling the working time of dental materials, such as cements, is based on controlling the temperature of the mixing slab. This includes zinc phosphate and glass ionomer cements mixing process. ,,
Although the importance of temperature of slab and mixing instruments on dental materials working time and properties is established, still there is no specific and practical device for this aim. It's clear that the local room temperature is not always controlled by the dentist, so the necessity of a method to control temperature used before and during the manipulation of dental materials triggered an idea in our mind to invent the needed device.
The present article is related to a method of controlling the temperature of a matter, using low levels of electricity with no means of gas or electric resistance. It presents a device for temperature control of dental materials using the abovementioned method.
| Clinical Innovation|| |
The technical task of this invention is the ideal and comfort temperature regulation of dental materials, particularly dental cements and composite resins, which are capable of substantially eliminating the previous drawbacks. Within the scope of this research, it is crucial to be able heat up or cool down the dental materials mixing slab, selectively. Also, precise maintenance of the desired temperature during manipulation of the materials is an extra burden for this technical goal.
The function of the device is based on the electrical Peltier cells that can control the temperature by both cooling and heating. There are two particular ways by which a Peltier cell can be activated: The first condition heats up the material and the second condition cools down the materials. By passing a direct flow through conductive elements of the Peltier cell, with a desired direction, the cell gets activated. Concerning the flow direction, one side of the Peltier cell would heat up, whereas the other side would cool down. In this way, the system cools or heats the slab with the changing direction of the current. Comparing the room temperature and determined temperature of the slab by the operator, the device sets the appropriate sense for the flow, to reach the intended temperature. There are two temperature sensors within the device; one for determining the environment temperature and one for determining the temperature of the device slab on which the dental materials are placed.
The temperature control in this device depends on the cooler/heater elements, comprised of thermoelectric cooler (TEC) element, heat sink, and a fan [Figure 1]. The TEC element's function is based on Peltier effect. The fan and heat sink are provided for the ventilation system and scatter produced heat of the system. The number of TEC elements used depends on the output we need which usually is two. The ventilation device comprises of one main blowing fan positioned close to the heat sink and two accessory haustorial fans to provide circulation of air within the device and disperse heat. The dispersion fans are drivable in rotation to generate a continuous air stream from the Peltier system to the external atmosphere.
|Figure 1: Schematic view of the device: (a) expanded view, (b) compact view. 1: Peltier elements (heating/cooling elements), 2: Haustorial fans, 3: Heat sink, 4: Blowing fan, 5: Metallic plate for thermal conduction, 6: Thermoregulator of instruments, 7: Specialized matrix for instruments, 8: Temperature sensor, 9: Electronic control board, 10: LCD, 11: Wires, 12: Glass slab, 13: Holding clips for slab, 14: Control keys, 15: Air balcony, 16: Main frame|
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Physically, all elements, sensors, and electronic circuits are placed in a box-shaped conformation made of plastic or similar materials [Figure 2]. There are two conductive plates on the upper portion of which one is carved and engraved specifically for the dental mixing instruments and the other one is determined for slab seat. Additionally a graphic display screen is determined that shows settings and temperature changes.
|Figure 2: Upfront view of the device. 1: Control keys, 2: Specialized matrix for instruments (shape of the instruments are inscribed on the matrix), 3: Thermal conductor for slab, 4: LCD|
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Once the dental material, the temperature of which is wished to be controlled, is introduced into the device by a suitable electronic control unit, a reference temperature is inputted to bring the slab and dental material placed on from a starting temperature corresponding to the room temperature to the inputted temperature. Input of the reference temperature is carried out by entering can be both higher and lower than the room temperature so that the slab is selectively heated or cooled relative to the surrounding atmosphere, depending on the requirements. Preferably, the reference temperature is determined and inputted to a given value in the range of 0-50°C, for instance to a value of 200°C. The abovementioned temperature control was conceived for the use on zinc phosphate cement and glass ionomer, which is made up of powder and liquid.
| Discussion|| |
Temperature regulation in dentistry was the center of attention of many clinicians since past decades. This is because the temperature of the material and instruments affects many physical and biological properties. A case in point is controlling the heat produced during drilling the tooth with high speed rotary instruments, which is now well achieved by delicate engineering. , The physical properties of the dental materials such as cements, composites, and resin bonding, seemed to be affected by the temperature of the room and the instruments.
The control of heat generation and achieving a working time sufficient for proper clinical manipulation has been an issue of focus for many dentists. Routinely, dental materials are disposed to either hot or cold or room temperature environments such as refrigerator or ovens. This allows an approximate and imprecise control of the reaction rate of the dental materials. For instance, there has been vast efforts on manipulating mixing temperature of zinc phosphate cement in order to reach ideal working time and physical properties. Several studies have been published that discuss the advantages of cold temperature mixing of zinc phosphate cement. A review of the above articles indicates that mixing zinc phosphate cement on a cold slab does indeed result in a cement that is not only more convenient to use, but also comparable to a cement that is mixed using traditional techniques in terms of the physical properties. ,,
Certainly, the abovementioned conditions result in uncontrolled slowing down or acceleration of the setting reaction which is caused by imprecise and unforeseeable variations in temperature adjustment. For example, the cold slab technique, which consists of putting the slab and mixing the instruments in the refrigerator, lacks precise control of temperature. The refrigerator maintains the temperature in a wide range of temperatures. Also because of ventilation method of cooling, immediate synchronization of temperature is not obtained, until a certain period of time is passed. Moreover, the sterilization issue is still on debate. Oven or even incubators for heating some materials have mostly same problems, namely, uncontrolled temperature control and sterilization issue.
Introduced device overcomes the abovementioned problems. The present invention allows heating or cooling of dental materials relative to a room temperature depending on the desired setting rate during the mixing. Both abilities of temperature control and temperature maintenance leads to sustained control of setting reaction rate of the dental materials. For instance, temperature regulation is electronically controlled with a temperature variance of 0.5°C. It should be noted that the device is economical and it can work in low voltages like a laptop. The desired temperature is achievable in terms of seconds, as the start button is pressed. In order to reduce the environmental temperature interference, a removable vivid cap is designed. Sterilization is provided by arranging a ultraviolet (UV) lamp on the vivid cap to disinfect the device, in between device utilization periods.
It is worth noticing that the device and its unique method can be also exploited for many materials and fields in dentistry. This includes any application in which the temperature of the matter plays a role. As mentioned earlier, handling and physical properties of cements, such as zinc phosphates, can be effectively manipulated by adjusting the temperature. Using this device, a constant adjustment of temperature is feasible, avoiding any probable temperature variation. This results in more convenient handling and improved physical properties.  Pain reduction during anesthetic injection is another usage of this device. Injectable anesthetic carpules can be heated up to 37°C temperature, to have similar temperature with body core. A cooled instrument can be used for chilling the injection zone in oral cavity. Both the mentioned actions cut down the pain that a patient experiences during injection. Cooled instruments can also be used for easier establishment of hemostasis after oral surgeries, by putting the proper instrument on the surgical zone. Extreme cooling or heating of an instrument can be beneficial while doing vitality test of a tooth.
Dental composites are other beneficiaries of this device. Radical mobility would be promoted directly by thermal effect and indirectly as a result of the lowered system viscosity. By preheating the composites, better viscosity leads to improved clinical handling.  In addition, several studies have been shown that temperature also affects polymerization kinetics of resin composites.  Significant differences in this regard have emerged between the temperature of storage in refrigerator and intraoral temperature. Heating the composites, increases monomer conversion rate, in same conditions. Enhanced conversion is known to have positive effects on several properties, such as surface hardness, flexural strength and modulus, fracture toughness, tensile strength, and wear resistance, which are clinically relevant also for luting materials. ,
This apparatus can be improved by designing various matrices, specialized for different purposes and materials. This specialized matrix, which is a metallic pad, directly connected to the temperature controlled sector, leads to the most efficient temperature conduction. By way of illustration, a matrix with shape of an injection carpule is engraved can be utilized to give it a temperature of 37°C, suitable for injection. Each instrument can have its particular matrix for more convenient thermoregulation. A metallic container should be designed for impression material, such as silicones. Tiny pumps and pistons facilitate materials handling.
Further clinical and laboratory experiments are needed to illustrate clinical significance of this device. This includes investigation of physical properties of dental composites; resin bondings; impression material; cements, such as zinc phosphate; and glass ionomer.
Financial support and sponsorship
Conflicts of interest
This device has been patented in National Office of Patents and Industrial Properties of Iran with registration code of 83230. 
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[Figure 1], [Figure 2]