Development of three dimensional measuring program with frontal and lateral cephalometric radiographs: Part 2. 3-D visualization and measurment program for maxillofacial structure

To establish systematic diagnosis and treatment planning of dentofacial deformity patient including facial asymmetry or hemifacial microsomia patient, comprehensive analysis of three dimensional structure of the craniofacial skeleton is needed. Even though three dimensional CT has been developed, landmark identification of the CT is still questionable. In recent, a method for correcting cephalic malpositioning that enables accurate superimposition of the landmarks in different stages without using any additional equipment was developed. It became possible to compare the three-dimensional positional change of the maxillomandible without invasive procedure. Based on the principle of the method, a new program was developed for the purpose of diagnosis and treatment planning of dentofacial deformity patient via three dimensional visualization and structural analysis. This program enables us to perform following menu. First, visualization of three dimensional structure of the craniofacial skeleton with wire frame model which was made from the landmarks observed on both lateral and frontal cephalogram. Second, establishment of midsagittal plane of the face three dimensionally, with the concept of "the plane of the best-fit". Third, examination of the degree of deviation and direction of deformity of structure to the reference plane for the purpose of establishing surgical planning. Fourth, simulation of expected postoperative result by various image operation such as mirroring, overlapping.

Stability of orthognathic surgery for cleft lip and palate patients

To evaluate the stability after orthognathic surgery in cleft lip and palate patients using rigid fixation, 20 patients underwent primary repair in childhood and later developed a jaw deformity and malocclusion that required orthognathic surgery were reviewed. Two groups, one of 10 patients performed Le Fort I osteotomy with sagittal split ramus osteotomy and one of 10 patients with sagittal split ramus osteotomy of the mandible, were evaluated. Each group had unilateral cleft only and all alveolar cleft sites had been grafted with autogeneous bone before the orthognathic surgery. The amount of surgical movement and relapse were compared in both horizontal and vertical dimensions. Two-jaw surgery group was more stable than mandibular surgery only group in mandibular position (p< 0.05). Statistically significant relapse was observed in mandibular skeletal point in mandibular surgery group (p<0.05). There was no statistically significant relapse in the skeletal point of two-jaw surgery group. However, the correlation between the horizontal surgical movement and relapse was detected (r = 0.88). This correlation indicates the need of overcorrection. The presence of scar tissues and relatively deficient maxillary bone could be attributed to this close relation between the surgical change and relapse.