Accelerated gamma ageing process for dental materials

Abstract

The present disclosure is a new accelerated artificial ageing / degradation method designed for dental materials. This method, referred to as an accelerated gamma ageing process and consisting of six steps, will be used to enable determination, within a short period of time, of how dental materials are affected over time by natural gamma radiation. Within the scope of the invention, how a gamma ageing apparatus of suitable characteristics should be configured in order to ensure irradiation of samples produced in compliance with standards for dental materials intended to be examined by material performance tests under required conditions is also explained in detail as part of the process in the fourth step.

Description

[0001] ACCELERATED GAMMA AGEING PROCESS FOR DENTAL MATERIALS TECHNICAL FIELD

[0002] The present disclosure relates to a new accelerated artificial ageing method (accelerated gamma ageing process) developed in order to foresee changes that may occur over time in the use of dental materials.

[0003] BACKGROUND ART

[0004] Nuclear Physics is a branch of science that covers subjects such as the structure of the atomic nucleus, nuclear interactions, nuclear energy, and radiation physics. Nuclear physics principles are utilised in various applications across many fields, ranging from basic sciences to engineering, and from medicine to dentistry. Radiation physics generally encompasses subjects related to radioactivity. Among the areas of interest of radiation physics are the nature of radiation, the interactions of radiation with matter, and the biological effects of radiation. In radiation physics, studies conducted on types of ionising radiation originating from natural or artificial sources are quite common. Therefore, Nuclear Physics is a technical field of critical importance for investigating the effects of gamma radiation, which has ionising properties, and for its use in material testing.

[0005] Dentistry is a field of health science that examines the structure, functions, and diseases of the head, face, mouth, jaws, and teeth, and that is devoted to the prevention or treatment of related diseases. Dentists are specialised individuals who manage this process and make decisions regarding the selection of the most suitable dental materials to be used. In parallel with developments in materials science, dental materials are continuously being updated. If the dental materials required for treatment are to be used in the patient’s mouth for a long period of time, the performance and reliability of these materials must be known in advance.That is, factors such as the resistance of these materials to intraoral conditions, their biocompatibility, and the physical and chemical changes that may occur in the materials over time, etc., must be known before the treatment process. For this reason, dental materials are subjected to accelerated artificial ageing / degradation processes that simulate different conditions, and subsequently, specific tests are applied to determine how the relevant property of the material changes over time. While the results of such studies provide information on which materials may be preferred, they also offer significant contributions and innovations to the sector in terms of both scientific studies in the relevant technical fields and practical applications.

[0006] Materials Engineering is a branch of science that investigates the structure, properties, and performance of materials. Methods of materials science are used for the development and optimisation of dental materials (such as composites, ceramics, metals, etc.), as well as for analyses relating to the chemical, physical, and mechanical properties of these materials.

[0007] Biomaterials engineering and biomedical engineering are disciplines concerned with the design and development of materials that can interact with biological systems. It is important to evaluate the resistance of materials to intraoral conditions and their biocompatibility for materials to be used in dentistry.

[0008] Medicine is a broad discipline that deals with the protection of human health, the treatment of diseases, and the provision of healthcare services, and that encompasses many branches. In some applications of medicine, such as surgery, various materials, biomaterials, and implants that show similarities to dental materials are used. The use of appropriate materials is extremely important for the successful completion of patients’ treatment processes and recovery stages. The reliability of these materials and the performance they exhibit throughout the process affect the general health status of patients. Dentistry and medical technical fields are two disciplines that can complement each other while providing healthcare services, in which innovations in one field can be adapted to the other and joint research can be carried out. Material evaluation tests that include the accelerated gamma ageing process that is the subject of the invention enable new research and development projects to be carried out in both fields. Thus, it ensures the design of new materials that are more suitable for theintended use, as well as the improvement of the quality of existing materials in use, both in terms of dentistry and the relevant branches of medicine.

[0009] The invention is directly related to the sector in which dental material manufacturers supplying materials to this technical field operate, since it is directed to dental materials such as ceramics, composites, metals, polymers, or hybrid materials that are frequently used in applications within the technical field of Dentistry. The sector in which dental material manufacturers operate is generally affiliated with the industrial branch active in the field of medical devices and healthcare products. In the sector, there are many domestic and foreign companies engaged in the production of dental materials (some of the globally recognised specialised companies include; 3M ESPE, Dentsply Sirona, Ivoclar Vivadent, Kerr Dental, Vita Zahnfabrik, GC Corporation, Heraeus Kulzer, Coltene, Shofu, Bisco Dental Products, Kuraray Noritake Dental, Zhermack, Panadent, and Dentsply Caulk, while some of the dental material manufacturers / suppliers in our country may be exemplified by the companies Imicryl, Gulsa, inci Dental, Yagmur Dental, Efes Dental, Oncu Dental, interdent, Beyaz Dental, and Zircon Dental).

[0010] The suitability, performance, and reliability of a dental material for treatment and restoration processes must be investigated and determined before its clinical use. For this reason, changes that may occur over time in dental materials that are intended to be used by the patient for a long period are tested using various scientific methods. In order for these tests to be carried out, samples produced from dental materials must first be aged by means of certain accelerated artificial ageing processes that simulate different usage conditions within the oral cavity. Thus, it becomes possible to foresee the condition of the material to be used after a certain period of time (for example, after 1 , 2, 5, 10, or 20 years). Existing accelerated artificial ageing processes for dental materials within the scope of the technical field of Dentistry are known as ageing by water storage, ageing by pH cycling, ageing by mechanical occlusal loading, ageing by ultraviolet light, and ageing by the thermal cycling method. For materials used in the other technical fields specified within the scope of the application, additional ageing processes are involved, such as ageing by humidity and temperature exposure, ageing by cyclic mechanical loading, chemical ageing, ageing by freeze-thaw cycles, and various abrasion processes.Our invention can be used not only in the Dentistry sector, but also for materials of similar nature that are studied and / or consumed in the technical fields related to Materials Engineering, Aerospace Engineering, Civil Engineering, Physics / Physics Engineering, Chemistry / Chemistry Engineering, Medicine, Biomaterials Engineering, Biomedical Engineering, Architecture / lndustrial Design, Textile Engineering, Automotive Engineering, Mechanical Engineering, and the defence industry.

[0011] Nevertheless, all living and non-living entities present in our environment are inevitably exposed to natural radiation. Gamma rays, which are high-energy electromagnetic waves, have deep penetration capability. Gamma radiation originating from natural radioactive sources is in continuous interaction with dental materials, as with all other substances. It is possible to age a material in a controlled manner by using gamma rays. However, in the sector, there is no accelerated gamma ageing process designed to investigate how dental materials are affected when exposed to natural gamma radiation. Our invention has an original approach developed in order to eliminate this deficiency in the sector and is an accelerated ageing process based on the irradiation of dental materials at doses equivalent to the natural gamma radiation to which they will be exposed over the years.

[0012] Although some scientific studies exist in which various materials are irradiated with gamma radiation using radioactive sources having different activities, the majority of these studies are directed towards examining the behaviour of materials to be used in nuclear applications under high radiation effects (or situations that may arise as a result of accidental irradiation). In industrial applications, the focus has been more on the disinfection and sterilisation of materials or on extending the shelf lives of certain products. Another area in which gamma rays are used relates to the testing and calibration of dosimeters that radiation workers are required to wear. In the literature review we conducted, no accelerated ageing process similar in nature to the study proposed by our invention (that is, directed towards the irradiation of dental materials at doses corresponding to the natural gamma radiation to which they will be exposed during their service life) has been encountered.THE AIM OF THE INVENTION

[0013] The main aim of the invention is to enable the understanding of how dental materials are affected by natural gamma radiation.

[0014] The aim of the invention is to enable the prediction of changes that will occur over time in the use of dental materials by using the accelerated gamma ageing process in material performance tests.

[0015] Another aim of the invention is to enable the utilisation of advantages such as material development, improved quality control capability, customer trust and satisfaction, competitive advantage, rapid product development, savings in research and development costs, and improvement of product shelf life, which the accelerated gamma ageing process will offer to the dental material manufacturing sector. Said advantages may be explained as follows:

[0016] • material development: By using this invention, manufacturers in the sector can better understand the performance of dental materials and optimise material formulations. This will lead to the emergence of new products that are more suitable for their intended use.

[0017] • improved quality control capability: The accelerated gamma ageing process has the potential to improve the quality control processes of dental materials. The manufacturer will be able to detect errors and deficiencies in the product at early stages.

[0018] • customer trust and satisfaction: Since the results of the material tests incorporating the invention will prove the suitability and durability of the dental material to be used to dentists and patients, consumers will be inclined to prefer the product with confidence.

[0019] • competitive advantage: Manufacturers using this invention for performance and reliability tests conducted on dental materials will stand out compared to other competing companies, as they will be able to respond more rapidly to market needs.

[0020] • rapid product development: Since the accelerated gamma ageing process enables rapid testing of the long-term performance of dental materials, it will make it possible for new products to be introduced to the market in a short time.• savings in research and development costs: Since rapid test processes can be carried out instead of long-term studies to examine dental materials intended for long-term use, research costs will be reduced together with time savings, and the production process will become more efficient.

[0021] • improvement of product shelf life: Taking into account the effect of natural gamma radiation during the determination of the shelf life of dental materials will enable the shelf life to be optimised in a more realistic manner.

[0022] Another aim of the invention is to enable the accelerated gamma ageing process to be used for performance tests of materials of similar structure consumed in other technical fields and also for related scientific research.

[0023] BRIEF DESCRIPTION OF THE INVENTION

[0024] Everything present in our environment is under the influence of ionising radiation that is continuously produced by natural mechanisms on the Earth. This radiation, which has sufficient energy to ionise the atoms of the object it interacts with when it encounters matter, can be categorised as alpha particles, beta particles, and gamma rays. Among these naturally sourced radiations, gamma rays are the most penetrating type of radiation, that is, when they interact with an object, they can progress into the internal structure of the material and transfer energy to the atoms along their path. In this way, they may cause changes in the structure of the material. Gamma rays are the highest-energy electromagnetic waves. They arise as a result of nuclear processes undergone by naturally radioactive elements such as uranium, thorium, radium, and potassium found in the Earth’s crust. At least 20% of the radiation dose received due to natural sources originates from exposure to gamma rays.

[0025] Like everything else in our world, dental materials are also continuously irradiated by naturally sourced gamma radiation. However, how dental materials are affected by natural gamma rays is a unique problem that has not yet been investigated. In order to systematically study this subject, it is necessary to develop an ageing / degradation method that incorporates a radioactive source producing gamma rays. The invention has been designed to eliminate this deficiency and comprises an accelerated ageing process that enables the irradiation of dental materials at doses equivalent to the natural gamma radiation to which they will be exposed over time. By means of thisproposed new ageing process, doses equivalent to the natural gamma radiation to which dental materials will be exposed during their service life can be applied to the material within a short period of time, and thus, material performance tests conducted for dental materials will reflect the real situation more accurately. In a scientific study carried out by the inventors, six different dental composite materials widely used in dentistry were examined using the accelerated gamma ageing approach, and it was statistically proven that this new method, which has not been taken into consideration to date for colour measurement studies in dentistry, should be included among accelerated artificial ageing processes.

[0026] Existing studies carried out using gamma rays are observed in industrial, healthcare, and research fields. In our country, there are quite a limited number of gamma irradiation centres belonging to the public and private sectors (such as TENMAK in Istanbul, GAMMA-PARK in Tekirdag, and the Calibration and Measurement Laboratory of Ankara University in Ankara). While box-type irradiation centres generally involve applications related to the disinfection and sterilisation of materials or the shelf lives of certain products, research laboratories carry out applications related to dosimeter tests and certain scientific studies. In irradiation centres abroad, in addition to similar studies, there are investigations relating to accidental irradiation and the behaviour of materials to be used in nuclear applications under high radiation effects. The radiation doses required for the accelerated ageing process proposed by the invention may be provided by making the necessary arrangements in some of these irradiation centres. However, for material performance tests, it will be more appropriate to use the design proposed by the invention, in which irradiations equivalent to natural gamma radiation levels in the milliGray range to which materials will be exposed during their normal service life (generally between 1 and 20 years) can be directly carried out.

[0027] BRIEF DESCRIPTION OF THE FIGURES

[0028] Figure 1 shows the schematic implementation systematics of the gamma ageing method.REFERENCES IN THE FIGURES

[0029] I. Irradiation chamber

[0030] K. Control chamber

[0031] 1. Camera

[0032] 2. Gamma detector

[0033] 3. Material samples

[0034] 4. Irradiation window

[0035] 5. Radioactive source

[0036] 6. Shield

[0037] 7. Monitor

[0038] 8. Control system

[0039] 9. Detector display

[0040] 10. Ventilation unit

[0041] 11.Area monitors

[0042] 12. Automation system

[0043] 13. Compressor

[0044] 14. Rail System

[0045] DETAILED DESCRIPTION OF THE INVENTION

[0046] In this detailed description, the subject of the invention is explained by means of examples solely for better understanding of the subject matter, without creating any limiting effect.

[0047] The invention, which is described in detail below, relates to an accelerated gamma ageing / degradation method for dental materials.

[0048] The gamma ageing method that is the subject of the invention is set forth by implementing the following process steps:i. Preparing material samples (3) from the dental materials to be examined, in a number and dimensions compliant with standards;

[0049] ii. Forming experimental groups to be aged and control groups that will not be aged;

[0050] iii. Subjecting the materials in the control groups to the relevant material performance tests;

[0051] iv. Performing gamma irradiation on the material samples (3) in the experimental groups by means of a radioactive source (5);

[0052] v. Subjecting the irradiated material samples (3) in the experimental groups to the relevant material performance tests;

[0053] vi. Scientifically comparing the test results obtained for the experimental and control groups and evaluating the results.

[0054] Among the process steps mentioned above, in particular steps iv, v, and vi are the steps that reveal the innovative perspective of the invention and bring unique technical benefits in the field to which the invention relates.

[0055] The gamma irradiation unit in which the ageing process that is the subject of the invention is carried out comprises an irradiation chamber (I) that is shielded in compliance with regulations and contains a “class 3” radioactive source (5) (10>A / D>1 ) in accordance with the principles for classification of radioactive sources (5) determined by the Nuclear Regulatory Authority, and a control chamber (K) from which the irradiation operation is managed.

[0056] The irradiation process can be visually monitored from a monitor (7) in the control chamber (K) by means of a camera (1) placed in the irradiation chamber (I). The radiation dose transferred to the irradiation surface can be viewed on a detector display (9) located in the control chamber (K) by means of a suitable type of gamma detector (2). The material samples (3) to which the accelerated gamma ageing process will be applied are positioned on the irradiation surface.

[0057] A radioactive source (5) having suitable activity is placed in a movable mechanism within a cylindrical shield (6) of suitable thickness that includes an irradiation window (4) that can be opened when irradiation is to be performed. Cesium-137 having a halflife of 30 years or cobalt-60 having a half-life of 5.3 years may be used as the radioactive source (5). The movable mechanism within the cylindrical shield (6) has ahollow piston structure that is shielded at the bottom and top and includes a cavity in which the radioactive source (5) can be placed and can be moved upward ordownward by means of a hydraulic mechanism.

[0058] The hydraulic system that moves the piston is controlled by a control system (8) in the control chamber (K) by means of a compressor (13). When irradiation is not to be performed, the piston is lowered to a downward position within the cylindrical lead shield (6) and the irradiation window (4) is closed, thereby preventing the radioactive source (5) from performing irradiation. In this case, a green light will illuminate on the illuminated indicator on the cylindrical shield (6), visually indicating that the environment is safe in terms of gamma radiation. Before proceeding to the gamma irradiation process, the cover closing the irradiation window (4) located on the front face and upper part of the shield (6) will be opened, and after ensuring that no one is present in the irradiation chamber (I), the control system (8) will be used in the control chamber (K) to operate the compressor (13) so as to raise the piston carrying the radioactive source (5) to the upward position. In this case, the radioactive source (5) will be aligned with the irradiation window (4) and will expose the material samples (3) positioned on the irradiation surface to gamma rays. While the irradiation process is being carried out, a red light will illuminate on the illuminated indicator on the cylindrical shield (6), visually indicating that gamma radiation is present in the environment. The milliGray level of gamma radiation to which the dental material samples (3) will be exposed will be calculated depending on the number of years of accelerated ageing intended to be performed. For tests of dental materials, accelerated ageing processes are generally carried out for periods between 1 and 20 years.

[0059] This period may be increased or decreased according to the preference of the researcher. For example, for a one-year accelerated gamma ageing process, a dose equal to the amount that the material would receive in one year due to natural gamma radiation can be provided in a very short time by means of the gamma rays emitted from the radioactive source (5).

[0060] Once the desired dose amount is determined, before proceeding to the accelerated gamma ageing process, it is necessary to ensure that the same dose amount will reach the irradiation surface. For this purpose, the system is first operated idle, that is, without the material samples (3) placed on the irradiation surface. By adjusting the distancebetween the irradiation plane and the radioactive source (5) located at the level of the irradiation window (4) and the irradiation duration, the dose amount to be transferred to the irradiation plane is measured by the gamma detector (2). The detector (2) that measures the irradiation surface and the dose amount on this surface is positioned on a movable carrier rail system (14). Bringing this platform closer to or further from the radioactive source (5) and aligning it with the radioactive source (5) (by moving in rightleft, forward-backward, upward-downward directions) is achieved by means of an automation system (12) that enables this system to be controlled from the control chamber (K). The mentioned automation system (12) is a system that incorporates both hardware and software components.

[0061] When the desired dose amount and the dose amount transferred to the irradiation plane are equalised, the distance and irradiation duration values are recorded, and the irradiation setup is closed using the control system (8). There are area monitors (11) in the irradiation chamber (I) and in the control chamber (K) that continuously measure the radiation levels in the environment. The radiation levels in these chambers are monitored on the detector display (9) located in the control chamber (K). When the radiation level in the irradiation chamber (I) exceeds the limit level, the air in the environment can be filtered and discharged by operating a ventilation unit (10) capable of creating negative pressure, controlled from the control chamber (K). After each irradiation operation, the area monitors (11 ) must be checked from the detector display (9) in the control chamber (K), and when necessary, the air in the irradiation chamber (I) must be filtered and discharged through the ventilation unit (10).

[0062] When safe working conditions are established in the irradiation chamber (I), the dental material samples (3) placed on the irradiation plane will be irradiated by activating the predetermined irradiation duration and distance information from the control chamber (K) and repeating the same operating procedure. Thus, the material samples (3) subjected to the accelerated gamma ageing process will be ready for the desired material performance tests.

[0063] The functions of the components forming the gamma ageing systematics for dental materials are as follows:• There is an irradiation chamber (I) containing a “class 3” radioactive source (5) (10>A / D>1) according to the classification principles for radioactive sources (5) determined by the Nuclear Regulatory Authority.

[0064] • There is a control chamber (K) from which the irradiation operation is managed.

[0065] • There is a camera (1 ) placed in the irradiation chamber (I) that provides visual data transmission to enable the user to monitor the irradiation operation performed in the irradiation chamber (I) via a monitor (7) located in the control chamber (K). • There is a gamma detector (2) for measuring the amount of gamma rays to be applied by the mentioned radioactive source (5).

[0066] • There are material samples (3) to be subjected to the gamma ageing process. • There is an irradiation window (4) that automatically opens to allow irradiation when activation by the radioactive source (5) is to be performed and automatically closes after activation to protect users from radioactivity.

[0067] • There is a radioactive source (5) used to expose the material samples (3) to gamma radiation at the desired / predefined dose.

[0068] o Cesium-137 with a half-life of 30 years or cobalt-60 with a half-life of 5.3 years is used as the radioactive source (5).

[0069] • There is a cylindrical lead shield (6) in the irradiation chamber (I), in which the radioactive source (5) is placed, that includes an irradiation window (4) that can be opened and closed, and that prevents radiation emitted from the radioactive source (5) from escaping when irradiation is not performed.

[0070] • There is a monitor (7) that transmits the images obtained by the camera (1 ) located in the irradiation chamber (I) to the user in the control chamber (K).

[0071] • There are area monitors (11) that continuously measure the radiation in the environment and transmit the measurement data, allowing the instantaneous radiation levels in the irradiation chamber (I) and the control chamber (K) to be monitored from the detector display (9).

[0072] • There is a detector display (9) for detecting, monitoring, and tracking by users in the control chamber (K) the radiation levels measured by the area monitors (11) in the irradiation chamber (I) and the control chamber (K).

[0073] • There is a ventilation unit (10) that can refresh / ventilate the ambient air by creating negative pressure when the radiation level in the irradiation chamber (I) exceeds the limit value.• There is a rail system (14) enabling the platform on which the detector (2) that measures the irradiation surface and the dose amount on this surface is positioned to move back and forth.

[0074] • There is a control system (8) that allows the hydraulic system, which moves the piston carrying the radioactive source (5) up and down within the shield (6), to be operated from the control chamber (K) by means of a compressor (13).

[0075] • There is an automation system (12) controlled from the control chamber (K) to ensure that the platform carrying the irradiation plane on which the material samples (3) are suspended and the gamma detector (2) measuring the irradiation amount is brought closer to or moved away from the radioactive source (5) and aligned with the radioactive source (5).

[0076] The application steps of the invention are given below:

[0077] ❖ Adjusting the distance of the irradiation surface from the radioactive source (5) and performing the alignment process with the automation system (12), following the determination of the sample position and irradiation duration according to the dose amount to be applied to the material samples (3);

[0078] ❖ Positioning the material samples (3) to be subjected to the accelerated gamma ageing process on the irradiation surface;

[0079] ❖ Operating the hydraulic system by activating the control system (8) that controls the compressor (13) from the control chamber (K) in order to raise the radioactive source (5) located in the movable piston mechanism inside the cylindrical shield (6) to the level of the irradiation window (4), and raising the radioactive source (5) to the upper position, to the level of the irradiation window (4);

[0080] o When irradiation is not to be performed, lowering the piston within the cylindrical lead shield (6) and closing the irradiation window (4) to prevent the radioactive source (5) from irradiating;

[0081] o In this case, lighting a green light on the illuminated indicator on the cylindrical shield (6) to visually indicate that the environment is safe in terms of gamma radiation;

[0082] ❖ Before proceeding to the gamma irradiation process, opening the cover that closes the irradiation window (4) located on the front face and upper part of the shield (6) from the control chamber (K) via the control system (8), after ensuringthat there is no one in the irradiation chamber (I), and starting the irradiation process;

[0083] ❖ By means of the radioactive source (5) aligned with the irradiation window (4), exposing the material samples (3) positioned on the irradiation surface to gamma radiation at the desired dose;

[0084] o While the irradiation process is being carried out, visually indicating the presence of gamma radiation in the environment by lighting a red light on the illuminated indicator on the cylindrical shield (6);

[0085] ❖ When the irradiation process is completed, closing the cover of the irradiation window (4) via the control system (8) from the control chamber (K);

[0086] ❖ Lowering the piston carrying the radioactive source (5) within the cylindrical shield (6);

[0087] ❖ Checking the ambient radiation levels measured by the area monitors (11 ) from the detector display (9) in the control chamber (K);

[0088] ❖ Ventilating the environment through the ventilation unit (10) when the radiation level in the irradiation chamber (I) exceeds the limit value;

[0089] ❖ After ensuring that it is safe to enter the irradiation chamber (I), going into the irradiation chamber (I) and collecting the material samples (3) that have been subjected to the accelerated gamma ageing process, making them ready for material performance tests.

[0090] The process is completed by implementing these method steps.

Claims

CLAIMS1. An ageing unit configured to enable the ageing processes of dental material samples (3) characterized by comprising;• an irradiation chamber (I) containing a radioactive source (5);• a control chamber (K) from which the irradiation operation is managed;• a gamma detector (2) for measuring the gamma rays to be applied to the material samples (3);• an irradiation window (4) that automatically opens to allow irradiation when activation by the radioactive source (5) is to be performed and automatically closes upon completion of activation in order to protect users from radioactivity;• a radioactive source (5) configured to expose the material samples (3) to gamma rays;• a cylindrical shield (6) that prevents radiation emitted by the radioactive source (5) from exiting into the irradiation chamber (I) when the irradiation operation is not performed and that includes an irradiation window (4) for the irradiation operation;• a ventilation unit (10) capable of ventilating the environment by creating negative pressure when the radiation level in the irradiation chamber (I) exceeds a limit value;• a rail system (14) configured to enable back-and-forth movement of the detector (2) that measures the irradiation surface and the dose amount on this surface; and• an automation system (12) configured to enable the platform to be moved closer to or further from the radioactive source (5) and to be aligned with the radioactive source (5).

2. The ageing unit according to claim 1 characterized by comprising; a camera (1) that is placed in the irradiation chamber (I) and that provides visual data transmission via a monitor located in the control chamber (K) in order to enable the user to monitor the irradiation operation carried out in the irradiation chamber (I).

3. The ageing unit according to claim 1 wherein mentioned radioactive source (5) is cesium-137 having a half-life of 30 years or cobalt-60 having a half-life of 5.3 years.

4. The ageing unit according to claim 1 characterized by comprising; a monitor (7) that enables images obtained by the camera (1) located in the irradiation chamber (I) to be transmitted to the user in the control chamber (K).

5. The ageing unit according to claim 1 characterized by comprising; a detector display (9) in order to enable detection and monitoring of the radiation levels in the irradiation chamber (I) and in the control chamber (K) from the control chamber (K).

6. The ageing unit according to claim 1 characterized by comprising; area monitors (II) that continuously measure radiation in the environment and transmit measurement data, in order to enable the radiation levels in the irradiation chamber (I) and in the control chamber (K) to be monitored via the detector display (9).

7. The ageing unit according to claim 1 characterized by comprising; a control system (8) in order to enable the hydraulic system that moves the piston to be operated from the control chamber (K) by means of a compressor (13).

8. A method for applying a gamma ageing process to dental material samples (3), characterized by comprising the steps of;• positioning material samples (3), of preselected dimensions and quantity, to which an accelerated gamma ageing process is to be applied, on a movable platform having an irradiation surface on an upper side thereof;• adjusting, according to a predetermined dose amount to be applied and an application duration, a horizontal distance of mentioned platform from a radioactive source (5) by means of a rail system (14) controlled via an automation system (12);• raising mentioned platform, by means of the automation system (12), to a level of an irradiation window (4) of a cylindrical shield (6), which is a height at which gamma irradiation is to be performed;• raising the radioactive source (5) located in a movable piston mechanism within the cylindrical shield (6) to the level of the irradiation window (4) by activating a control system (8) that controls a compressor (13);• opening, by means of the control system (8), a cover closing the irradiation window (4) located on a front face and an upper portion of the shield (6);• exposing the material samples (3) positioned on the irradiation surface to gamma radiation at a desired dose by means of the radioactive source (5) aligned with the irradiation window (4); and• measuring, by means of a gamma detector (2), gamma irradiation applied during the irradiation process.

9. The method according to claim 8 characterized by comprising; the process step of lowering the piston into the cylindrical lead shield (6) and closing the irradiation window (4), thereby preventing irradiation by the radioactive source (5), when irradiation is not to be performed.10.The method according to claim 8 characterized by comprising; the process step of illuminating a green light on the illuminated indicator on the cylindrical shield (6), thereby visually indicating that the environment is safe in terms of gamma radiation, when irradiation is not to be performed.

11. The method according to claim 8 characterized by comprising; the process step of closing the cover of the irradiation window (4) by means of the control system (8) from the control chamber (K), when the irradiation process is completed.12.The method according to claim 8 characterized by comprising; the process step of lowering the piston carrying the radioactive source (5) into a downward position within the cylindrical shield (6), when the irradiation process is completed.

13. The method according to claim 8 characterized by comprising; the process step of ventilating the environment by means of the ventilation unit (10), when the radiation level in the irradiation chamber (I) exceeds a limit value.

4. The method according to claim 8 characterized by comprising; the process step of illuminating a red light on the illuminated indicator on the cylindrical shield (6), thereby visually indicating the presence of gamma radiation in the environment, while the irradiation process is being carried out.

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