抄録
The Index of Orthognathic Functional Treatment Need （IOFTN） is an index used to assess the indication for surgical orthodontic treatment, and was conceptualized in the United Kingdom. IOFTN is categorized from Category 1 （none） to Category 5 （very great）, and each category is divided into several subcategories by various factors such as occlusal relationship and the presence or absence of functional difficulties. The aim of this study was to determine whether IOFTN is a useful index for Japanese patients. The subjects for this retrospective assessment were 128 patients with jaw deformities for whom orthognathic surgery was performed in our hospital （Niigata University Medical and Dental General Hospital） during the period from January 2015 to December 2017. The subjects included 37 males and 91 females （average age: 23±8years）. A combination of Le FortⅠ osteotomy and bilateral sagittal split osteotomy was used in 79 cases （61.7％）, a combination of multi-segmental Le Fort I
type osteotomy and bilateral sagittal split osteotomy was used in 8 cases （6.3％）, bilateral sagittal split osteotomy was used in 36 cases （28.1％）, and other techniques were used in 5 cases （3.9％）. The ANB angle was measured to classify the skeletal pattern as follows: Class 1 （1≦ANB≦4）, Class 2 （ANB＞4）, and Class 3 （ANB＜1）. The most frequent skeletal pattern was Class 3 （82 cases: 64.1％）. 29 cases （22.7％） were Class 1 and 17 cases （13.3％） were Class 2.
The results showed that 118 patients （92.2％） were categorized as Category 4 or 5 with great need for surgical orthodontic treatment. No patient was categorized as Category 1 or 2. In conclusion, IOFTN might be an accurate indicator of treatment need for Japanese patients with jaw deformity requiring surgical orthodontic treatment.
