A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part I

Abstract

This article presents a soft-tissue analysis which demonstrates the inadequacy of using a hard-tissue analysis alone for treatment planning. The material and methods used to develop this technique came from years of observation and description of patients from the private practice of the author. The findings indicate that, in general, for adolescents the normal or usual thickness of the soft tissue at point A is 14 to 16 mm. As point A is altered by tooth movement, headgear, etc., the soft tissue will follow this point and remain the same thickness. When there is taper in the maxillary lip immediately anterior to the incisor, as in protrusive dentures, the tissue will thicken as the incisors are moved lingually until the tissue approaches the thickness at point A (within 1 mm. of the thickness at point A). When the lip taper has been eliminated, further lingual movement of the incisor will now cause the lip to follow the incisors in a one-to-one ratio. These concepts are predictable in adolescents when the lip thickness at point A is within the normal range. Some exceptions are as follows: Even if there is lip taper, if the tissue thickness at point A is very thin (for example, 9 to 10 mm.), the lip may follow the incisor immediately and still retain the taper. If the tissue at point A is very thick (for example, 18 to 20 mm.), the lip may not follow incisor movement at all. Adult tissue reaction is similar to the first exception. Even though there may be lip taper, the lips will usually follow the teeth immediately. Cases are presented to demonstrate these concepts and to illustrate a normal or acceptable range of variation for facial harmony related to variations in skeletal convexity.