Tiếng Việt
Where is the infrared camera located within the ceramic furnace?
In the Programat P510, for example, the IR camera is located at the back of the furnace near the furnace head opening mechanism behind the cover. In order for the lens to detect the restoration, the cover plate has to have a corresponding opening. In this position within the furnace, the camera is protected from the heat in the firing chamber and optimally positioned to detect the chamber contents during the predrying process.
Since the camera cannot be located within the firing chamber itself due to thermal engineering reasons, an object’s temperature can only be measured with the furnace head open or closed to within 30 millimetres. The critical processes for the ceramic material take place during the predrying stage with an open furnace head. The IR camera is used during this phase.
How many pixels does the camera have? How many points can it measure?
The thermal images taken by the IR camera of the Programat P510 consist of approximately 1000 pixels. There will be at least 2 measuring points on a thin single veneer. A large molar may have 12 or more measuring points. The surface of a measuring point depends on the distance. Near the firing tray on which the dental restorations are placed, the surface area of a measuring point is always smaller than 2.5 mm x 2.5 mm.
What are the advantages of using infrared imaging in a ceramic furnace compared with using conventional thermal elements?
In conventional dental furnaces a thermal element measures the temperature within the firing chamber. This thermal element is usually located in the upper part of the firing chamber and the restoration is usually positioned at a close distance. The software measures the temperature on the restoration while the furnace is closed and a correction factor is subsequently applied. However, when the restoration is predryed while the furnace head is open, draughts can distort the temperature reading on the restoration and the thermal element. This may cause temperature deviations. The preset time (closing time and predrying time) will not make allowance for these variations and the program will run by default. The occurrence of cracks and fractures in the ceramic is inevitable.
In contrast, infrared imaging allows the temperature on the restoration to be measured with a non-contact method. The Programat P510 does not rely on a correction factor to estimate the temperature on the restoration when the furnace is open. The IR camera always measures the precise temperature on the surface of the restoration even if there is a draught. This represents the greatest and most decisive advantage over furnaces that operate with conventional methods.
