Japanese Journal of Oral and Maxillofacial Surgery
Online ISSN : 2186-1579
Print ISSN : 0021-5163
ISSN-L : 0021-5163
Studies on cephalometric prediction for surgical correction of mandibular deformities
Part III. Cephalometric evaluation of various methods for prediction of soft tissue profile in orthognathic surgery for mandibular prognathism
MITSUO NISHIDA
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1989 Volume 35 Issue 1 Pages 31-45

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Abstract

In this study, morphological changes of skeletal class III craniofaces operated by sagittal splitting osteotomy of the mandibular ramus (male: 30, female: 40) were analyzed. On lateral head vlms, positional changes of the soft tissue and hard tissue were evaluated. On the basis of these results, fiive kinds of methods of postoperative prediction on soft tissue profile were instituted. Which method of prediction was the best was examined with external checks on other samples (male: 16, female: 17) about the amount of aberration of predictions in all measuring points, and the following results were obtained.
1. Judging totally from the sum of ranking numbers of aberration in all measuring points of mental soft tissue, the following ranking was found among the five kinds of methods.(1) Simple regrcssion linear analysis, (2) average changing rate from sfot tissue to hard tissuc, (3) multiple regression analysis, (4) avcrage positional relationship between soft tissue and hard tissue on the standard of cases normalized by surgical correction (by the author) and (5) average positional relationship between soft tissue and hard tissue on the standard of normal persons.
The methods based on the amount of positional changes were better than those based on average positional relationship.
2. Postoperative prediction of the upper lip needs average positional relationship between soft tissue and hard tissue, because few facts are gained from the amount of positional changes of the lower incisors and mental area. The method of average positional relationship on the standard of the cases normalized by surgical correction achieved much closer predictions than the standard method for normal persons.
3. Against the amount of backward movement of point B, Pogonion, and Menton, the rate of that of their neighboring soft tissues were 98%, 86%, 86% respectively. On the other hand much greater deviation in the rate of vertical movement was observed; therefore clinical application of those data was considered impossible.

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