Rapid palatal expansion. Part 3: strains developed during active and retention phases.

Patterns of strain accumulation/dissipation during the active and retention phases of rapid palatal expansion treatment were studied in a preliminary animal model (5 cats) followed by clinical study (14 patients). Two uni-axial strain gauges were bonded to the arms of a hyrax screw. The strain gauges were wired intraorally to a common male connector and protected against salivary assault.