Ultrasound in dentistry. Part 1--Biophysical interactions.

Ultrasound has many applications in the field of dentistry. However, it is only recently that the applications and effects of its physical properties have been rationalized and understood. Ultrasound may be generated by either magnetostriction or piezoelectricity, although the former is more commonly used in dental applications. Interactions of ultrasound with biological tissues may be caused by either thermal or mechanical mechanisms. The mechanical forces produced may be a result of cavitation, acoustic microstreaming and radiation pressure forces. An understanding of these interactions allows a more knowledgeable appreciation of the effectiveness, safety limitations and rationale of dental ultrasonic instrumentation.