Mandibular third molars and postretention crowding.

T he role of mandibular third molars in the relapse of lower anterior crowding following the cessation of retention in orthodontically treated cases has provoked much speculation in the dental literature over the past 115 years. In 1859 Robinson’ wrote : “. . the dens sapicntiae . . is . . frequently the immediate cause of irregularity of the teeth by the pressure exerted towards the anterior part of the mouth.” As recently as 1971, in a survey of more than 600 orthodontists and 700 oral surgeons, TAaskin? fount1 that 65 per cent were of the opinion that third molars sometimes produce crowding of the mandibular anterior teeth. At present there is no unanimity of opinion as to the possible effect of third molars on mandibular incisor stability. The purpose of this study was to investigate whether mandibular third molars have a significant influence on posttreatment changes in the mandibular dental arch and specifically on anterior crowding relapse. The ahbrrviation RI3 will he usctl for mandibular thirtl molars throughout the text.