Which Line to Kiss. A Review of Reference Lines For Lip Profile.

Orthodontists have their own preferences in selecting the reference line for evaluation of the upper and lower lip in treatment planning and post treatment results. The reference line should provide the orthodontist with objective assessment of the facial esthetics. The reference plane selected should be sensitive, reliable with consistency. The commonly used reference line are: Rickett’s E- line, Holdaway’s line, Steiner’s S1- line, Burstone’s B- line and Sushner’s S2- line and Merrified Z-angle. This article reviews the planes and the studies evaluating them.