When the maxilla is significantly more narrow in the anterior region than in the molar region (and crowding is severe), a “Wipla” can make it possible to expand the arch and correct crowding without disturbing the posterior bite relationship. The expansion screw is hinged in the posterior segment, confining expansion to the anterior region. The anterior portion of the screw pivots, allowing up to 8mm of expansion. Note: Since this screw is available in only one size, it may not fit all cases. When such is the case, the Swing Lock Expander is a viable alternative.