Abstract
One of the possible causal factors of class 2 division 1 malocclusion is an abnormal form of anterior oral seal, known as the “tongue-to-lower-lip behaviour”. The elevating movement of the lower lip between the upper and lower incisor teeth, towards the forward-posturing tongue, produces an increased overjet and an incomplete overbite. The method of treatment described exploits the forces produced by the hyperactive lower lip. In achieving its special form of anterior oral seal, it can provide anchorage to the teeth of the lower arch in resisting the forward movement encouraged by the use of class 2 elastic force. Equally important is the manner in which the continued achievement of this type of abnormal anterior oral seal is made progressively mare difficult for the patient, encouraging the establishment of a normal lip-to-lip seal, upon which the prognosis of the treated result will become dependent.