Simon classification of malocclusion

Si·mon clas·si·fi·ca·tion of mal·oc·clu·sion

(sīmŏn klasi-fi-kāshŭn malŏ-klūzhŭn)
System that relates tooth position to the Frankfurt horizontal, midsagittal, and orbital planes. Teeth are considered in attraction/distraction if too close or too far from the Frankfurt plane; in contraction/distraction if too close or too far from the midsagittal plane, and in protraction/retraction if too anterior or too posterior to the orbital plane.