- 著者
-
高橋 功次朗
丹原 惇
森田 修一
小林 正治
池田 順行
林 孝文
齋藤 功
- 出版者
- 特定非営利活動法人 日本顎変形症学会
- 雑誌
- 日本顎変形症学会雑誌
- 巻号頁・発行日
- vol.27, no.1, pp.1-7, 2017
Cephalometric prediction is still widely used for treatment planning in surgical orthodontic patients. However, there have been few reports on the relationship between mandibular midline changes by orthognathic surgery and the amount of bilateral setback movement on lateral cephalograms. The aim of this study was to clarify the relationships between the difference in mandibular setback amount for deviated and non-deviated sides and the amount of middle region displacement on cephalometric prediction in patients with mandibular prognathism and deviation.<br>The subjects comprised 15 patients diagnosed as mandibular prognathism with skeletal deviation at the orthodontic clinic, Niigata University Medical and Dental Hospital. All patients underwent only mandibular setback surgery involving midline correction by sagittal split ramus osteotomy(SSRO). Frontal and lateral cephalograms taken just before and immediately after orthognathic surgery were used for measurements. X-Y coordinates were constructed using the occlusal plane on the preoperative lateral cephalogram for the X coordinate and the perpendicular line drawn intersecting the X line at the Sella for the Y coordinate. The amount of posterior movement of the distal segment and middle region displacement were determined by superimposition of pre-and postoperative lateral cephalograms. The postoperative midline changes were measured linearly using a study model taken at just before orthognathic surgery. We examined the relationship between the average amount of operative movement for deviated and non-deviated sides and the amount of anteroposterior changes of the incisal region. The relationship between the difference in operative movement for deviated and non-deviated sides and postoperative midline changes was also examined.<br>Significant correlations were found between the bilateral difference of operative movement and the amount of anteroposterior changes of the incisal region. A significant correlation was also revealed between the bilateral difference of operative movement and horizontal middle region. In addition, a significant regression formula was obtained as β=0.65α+1.17(α: bilateral difference of mandibular posterior movement (mm), β: lateral movement of mandibular midline(mm))by regression analysis.<br>The present results suggest that, in cases with skeletal deviation, it is possible to regard the average value of anteroposterior movement of distal segments on both sides as a predictive factor for the posterior position of the incisal region. Also, the results suggest that the amount of midline correction can be predicted from the bilateral difference of operative movement. Since there is diversity and much variation in the movement of distal segments, it is not easy to predict the amount of midline displacement during orthognathic surgery. However, this regression formula may be useful for orthodontists and surgeons to plan surgical orthodontic treatment.