Development of a Method of continuous Temperature Measurement for Microwave Denture Processing

A method of continuously measuring temperature during microwave irradiation was developed using a metal sheathed thermocouple. The temperatures recorded by this method were compared with those measured intermittently with a mercury thermometer. Samples of Sydney tap water (50 ml) were heated using a domestic microwave oven at High and Low powers which were the maximum (500 W) and minimum (50 W or 10%) powers of the oven, respectively. At 500 W, boiling was seen to occur within 1 min and the measurement with the mercury thermometer was omitted. The continuous temperature measurement with the thermocouple showed that the boiling point was reached at about 45 s. At 50 W the 10% work was shown by the delivery of 3 s microwave radiation which was repeated every 32 s. The boiling point was recorded at about 6 min, which was much earlier than the time (10 min) noted visually. The boiling point could not be registered with the mercury thermometer method. Visual observation or intermittent temperature measurement can result in an underestimation of temperature reached during microwave irradiation.