This research examined the frequency and type of facial asymmetry of 50 patients with mandibular deformity who visited the Department of Orthodontics of the hospital attached to Meikai University.
The method involved angle and distance measurements made from a standardized frontal facial photograph.
The mandibular deformity patients were divided into symmetrical and asymmetrical facial groups; and the latter were further classified into lower, middle, and middle and lower facial asymmetry subgroups. Of the 50 patients, 34% showed facial symmetry; and the remaining 66%, facial asymmetry. The asymmetry group comprised about 85% in the lower facial asymmetry subgroup and about 15% in the middle and lower facialasymmetry subgroup. In the cases of asymmetry, about 71% showed a shift toward the left side (about 29% toward the right side). There were no cases of asymmetry only in the middle face. The facial asymmetry was expressed as deformation in the downward direction from the subnasal line in the middle and lower facial asymmetry subgroups. The lower facial asymmetry subgroups showed deformation downward from the lip line.
The results of this research suggest that angular and linear measurements of frontal facial photographs of jaw deformity patients are a useful aid for analyzing symmetry.

View full abstract

In orthognathic surgery cases, facial asymmetry was examined by using facial photographs. Soft-tissue asymmetry was assessed subjectively and grades were given according to their severity. The subjective analysis was compared with the objective analysis by linear and angular measurements of the facial photographs. The soft-tissue asymmetry evaluated by the objective analysis was compared with the skeletal asymmetry assessed by the postero-anterior cephalograms. It was suggested that the line running from the soft-tissue nasion to the subnasale was appropriate to the mid-facial reference plane. In the comparative study between the subjective andthe objective soft-tissue analyses, it was shown that a facial asymmetry was visually felt by recognizing the lateral displacement of the chin and the right-left difference of the gonion. Such soft-tissue asymmetries were significantly correlated to the corresponding skeletal asymmetries. In orthognathic surgery cases having a facial asymmetry, correction of the skeletal asymmetry concerning the chin and the gonion position seemed to be important for making the soft-tissue symmetrical.

View full abstract

Recently, a bioabsorbable osteosynthesis system (BOS) that does not need a removal operation and causes fewer side reactions has been used in clinics, especially in jaw deformity and jaw fracture operations in the oral and maxillofacial region. This system cannot yet take the place of the metal osteosynthesis system (MOS) because of less strength and higher cost compared with MOS. We experienced a miniscrew fractured case of BOS in genioplasty which was caused by over-fasteningthe miniscrews. We therefore developed a new BOS in which the strength of the miniscrew and the shape of the miniplate were improved and a new torque screwdriver was employed.We applied the new BOS on orthognathic surgery and gained good results.

View full abstract

Intraoral vertical ramus osteotomy (IVRO) has become a useful surgical management to obtain better functional and esthetic results for patients with mandibular prognathism. Especially, unilateral IVRO performed in combination with sagittal splitting ramus osteotomy (SSRO) on the contralateral side has become a popular surgical management for mandibular prognathism with skeletal facial asymmetry. In this paper, three patients with asymmetric mandibles who underwent unilateral IVRO are reported, with evaluation of skeletal changes during pre-and post-operative treatment using frontal and lateral cephalometric radiographs. No remarkableskeletal shift of the mandible after surgery was observed in all cases, whereas cephalometric analysis indicated the slight positional change of condylar and posteroinferior and lateral jaw movements in two of the three cases. In occlusion, the unilateral IVRO seemed to be a useful technique for mandibular prognathism with skeletal facial asymmetry. However, the occlusal adjustment in postoperative treatment and further follow-up are required.

View full abstract

When sagittal split ramus osteotomy is performed for skeletal Class II cases, it is possible to encounter cases in which occlusal stability cannot be gained due to postoperative relapse. One possible causes is that the centric relation and the centric occlusion have not been obtained during surgery. Progressive condylar resorption (PCR) after surgery is another possible cause of relapse. We examined the evaluation of the condylar position after sagittal split ramus osteotomy. We suggest that the risk factors for PCR include a high mandibular plane angle, TMJ condition prior to surgery, and excessive movement or counterclockwise rotation of the distal segment during surgery. It is also reported that the rigid fixation of the condyle, by placing it above and behind during surgery, leads to factors which increase pressure on the bone and accelerate the changes in the bone after surgery. We performed a procedure to reduce pressure on the condyle, by adopting overcorrection and loose fixation such as transosseous wiring during surgery. We then studied the postoperative change of the mandibular joint's position and the skeletal form.
We monitored eight patients consisting of two males and six females who had undergone sagittal split ramus osteotomy for skeletal Class II cases. We adopted transosseous wiring for fixing proximal and distal segments, and used a surgical splint to provide overcorrection; we then performed the intermaxillary fixation for four weeks. We conducted standardized tomography of the mandibular joint prior to surgery, after surgery (within seven days), and three months after surgery. We took lateral cephalograms prior to surgery, after surgery, and ten to twelve months after surgery. We measured a longitudinal change of the condylar position by standardized tomography of the mandibular joint. First, we regarded a straight line connecting the postglenoid process (BNA) and lowest mark of the condylar process as a base line, and then measured the distance from the base line to the high point of the condyle. As there was some difference in cases in terms of actual measurement, we converted the preoperative measuring value to a standard value, and conducted a comparative assessment of the postoperative measuring value based on the standard value.
The head of the mandible position changed approximately 70% downward soon after surgery, however, three months after surgery it recovered up to near the samelevel as that before surgery.

View full abstract