Milestones in the development and practical application of functional appliances.

The current interest in functional appliances in the United States is based on apparent success of one or more modifications of appliances that have been used in Europe for many years. Because a number of authors considered these appliances the universal answer to treatment of malocclusions, many modifications were developed. The history is replete with changes induced by failures as well as successes, resulting in the current approach in Europe to the use of both fixed and removable appliances, separately or in combination, to achieve the best possible result. This historical discourse presents some of the background that is not well known in the United States. It should give the clinician a better understanding of the physiologic bases, as well as the reason for the broad gamut of appliances that have been used at one time or another. The original work of Andresen, Häupl, Petrik, Eschler, Balters, etc. is described, as well as the work of later contributors to the current "state of the art" in functional jaw orthopedics.