Stability of orthodontic treatment and dental extractions

Regarding the stability of sagittal correction, more specifically in the treatment of Class II malocclusion, there used to be a dogma, still recurrent in Orthodontics, that the molars should be finished in a Class I relationship to provide greater treatment stability. 3 Nevertheless, this assertion finds no support when treatment stability is analyzed comparatively, i.e., between protocols involving extractions of two maxillary premolars and nonextraction protocols. 4 A recent systematic review indicated as inconclusive whether or not stability would be achieved to a greater or lesser degree if a Class II treatment were performed with or without extractions. 5 On the other hand, there seems to be evidence, albeit relatively scant, indicating that cases with Class III malocclusion treated compensatorily with extractions of lower teeth are more stable than nonextraction cases. 6 , 7 Even if extractions appear to lessen the risk of relapse of compensatory orthodontic treatment of Class III malocclusion, the same results have been yielded by studies examining stability of non-surgical treatment of anterior open bite. Clinical studies have revealed that stability seems to improve when treatment in the permanent dentition is performed with extractions, be it in adolescents 8 or in adults. 9 It has been speculated that stability is improved in extraction treatments precisely because two mechanisms help in closing the anterior open bite, i.e., the “drawbridge principle,” and the mesialization of posterior teeth. 8 But why should we broach this subject again? Conversely, if the prospect of a lower chance of relapse of sagittal and vertical changes (anterior open bite) in extraction cases is true, it is highly likely that we are raising the risk of relapse with the aid of skeletal anchorage, in nonextraction cases.