Final answer:
The thermal or heat-producing current with a high rate of oscillation or vibration used for scalp and facial treatments is known as ultrasound diathermy, which utilizes high-intensity ultrasound energy converted to thermal energy to relieve pain and improve flexibility in tissues.
Step-by-step explanation:
The thermal or heat-producing current with a high rate of oscillation or vibration commonly used for scalp and facial treatments is called ultrasound diathermy. High-intensity ultrasound energy is converted to thermal energy, and intensities of 10³ to 104 W/m² are typically used. The frequencies used range from 0.8 to 1 MHz, and may aid in relieving pain and improving flexibility in overworked muscles. Caution is required to avoid tissue damage or 'bone burns' caused by overheating and cavitation, which can be made worse by the reflection and focusing of the ultrasound by joint and bone tissue.
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