In defense of the guidance theory of palatal canine displacement.

From the foregoing debate it will be quite clear that Peck et al. have provided ample evidence that may be used to fuel the arguments of both sides: 1. Their material does not contradict the possibility that environmental factors may give rise to palatal displacement of canines generated by genetic anomaly of the adjacent teeth. 2. The buccally displaced canine finds itself similarly environmentally compromised by the different factor of crowding which leads to its characteristic buccally ectopic guidance pattern. 3. (a) Canines that are transposed with the premolar, (b) others that have erupted ectopically, high in the buccal sulcus and in the absence of crowding, and (c) certain palatal canines whose root apex is located markedly distant from their designated site, may all be labeled as genetically controlled with a fair degree of confidence. 4. In between these clearly defined entities there exists a "gray area" in which it is probable that the etiology of the individual displaced teeth may be linked to a combination of circumstances that obey premise number 1 and premise number 2, to varying degrees. The guidance theory cannot provide the complete answer to the etiology of the palatally displaced canine. Were this so, we would find PDC every time there was an anomalous or missing lateral incisor. Equally, it may not yet be discounted out of hand and certainly not on the basis of the evidence provided in the article in question.