King and Pennel's free graft series: a defining moment revisited.

The free gingival graft is one of the most versatile and predictable procedures in current use. A review of the significant contributions leading to this procedure is presented. Reports of the free graft series of King and Pennel, as well as the reaction to its initial presentation by members of the Philadelphia Society of Periodontology, are introduced to the dental literature. The chronology of events leading to the rediscovery of the gingival graft procedure in the early 1960s suggests independent and nearly simultaneous clinical innovation took place in Sweden and the United States. Therefore, though fully acknowledging Hilding Björn's seminal contribution, substantial credit must be given to colleagues King and Pennel for introducing the gingival graft procedure to periodontics.