The purpose of this study was to investigate acoustically the influence of orthognathic surgery on the phonetic quality of patients with skeletal mandibular protrusion. Samples of speech sounds were collected from nine patients (seven females, two males) before and after orthognathic surgery.
The psychoacoustic analysis was carried out by 24 examiners using the paired comparison in naturalness of the five different Japanese words.
The acoustic analysis, based on the linear predictive coding (LPC), were applied to determine the lowest two local spectral peaks (Fl, F2) on the vowels. Fl and F2 were compared with the normal speakers, and the changes of Fl and F2 with orthognathic surgery were evaluated using 40 Japanese words.
The results were as follows:
1) The naturalness of speech has been improved in most patients after orthognathic surgery in the psychoacoustic analysis.
2) Distribution of Fl and F2 in patients after surgery approximated that of normal speakers.
3) The psychoacoustic and acoustic analyses have a significant correlation. It was suggested that improvement in naturalness of speech is associated with the changes of Fl and F2 by orthognathic surgery.

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The purpose of this study was to evaluate changes of masticatory function in patients that underwent sagittal splitting mandibular ramus osteotomy from before operation to one year after operation.
The subjects were 21 patients with orthognathic deformities, and the control group consisted of 21 people with individual normal occlusion assessed as having normal orthognathic function without cross bite.
The following masticatory examinations were done: measurement of maximum mouth opening, width of active potential of masseter muscle, occlusal contact area, occlusal force, masticatory performance and masticatory score. All examinations were done in 21 patients before operation, and 1, 3, 6 and 12 months after operation. The mean values of these indices of the subject group were compared with those of the control group, and the mean values before operation were compared with the mean values for each period of examination in the patient group.
The result was that masticatory function following orthognathic surgery showed a decline at 1 month after surgery but gradually increased at 3 months. The values of maximum mouth opening, width of active potential in masseter muscle, masticatory performance and masticatory score at 12 months after surgery were all greater than those found before operation; the readings were almost the same as those for the control group. The values of occlusal contact area and occlusal force increased only to the presurgical level even at 12 months after surgery.

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Conventional facial diagrams and craniofacial drawing templates for cephalometric analysis are not always adequate due to size differences in individual face. To solve this problem, cephalometric templates that can be enlarged or reduced in proportional to the patient's face size while maintaining anatomical features were created. These templates, called SUPERIMPOSER, were created as a computer file and can be printed on OHP film or ordinary paper to enable superimposing of cephalogram or trace of the patient.
SUPERIMPOSER easily compares, the patient's cephalogram, enabling the clinician to identify and determine rapidly the extent of dentoskeletal deformities.
The template ordinarily employs four types of superimpositioning, superimposition of overall facial structures at the anterior cranial base to reveal the position of the maxilla and the mandible, superimposition at the maxilla to clarify the maxillomandibular relation, and maxillary and mandibular superimposition to examine the size and form of the jaws of the individual.
Application of SUPERIMPOSER for surgical orthodontic treatment to three clinical cases is presented.

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The efficacy of recombinant human erythropoietin (Epo and Esp) was studied inpatients who underwent two jaw surgery for correction of jaw deformities after collection of 1200ml of autologous blood.
The patients were classified into group A (7 patients) with administration of Fe alone, group B (12 patients) with Fe and Epo (9 times), group C (5 patients) with Fe and Esp (3 times) and group D (6 patients) with Fe and Esp (4 times) depending on the results of blood examination. Mean Hb, RBC and Ht before surgery in group A were 12.1g/dl, 401×10⁴/μl and 35.9%, respectively. The decreases of these values before sugery were maximum in group A and yet the values were higher than those of the other groups. Despite significantly lower Hb and Ht before blood collection, mean Hb, RBC and Ht before surgery for groups B, C and D were 10.5-11.4g/dl. 354-386×10⁴/μl and 32.0-34.7%, respectively and they showed good recovery after surgery. Among these groups, group C showed the poorest results.
In conclusion, recombinant human erythropoietin, in particular Esp with a total of 4 injections, was most effective in restoring anemia after blood collection.

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Obwegeser II method was applied to an 18-year-old male patient with severe progenia and open bite.
The reasons for selecting this method were as follows;
1. His lateral cephalometric analysis revealed only excessive mandibular protrusion without any maxillary abnormality.
2. It was necessary for the mandible to be set back 14 mm posteriorly to obtain the ideal intermaxillary occlusion.
3. The anteroposterior width of his mandibular ramus was bilaterally narrow.
4. Furthermore, severe open bite still remained at the end of pre-surgical orthodontic treatment.
Postoperative cephalometric analysis revealed both skeletal stability and harmonious balance.
One of the advantages of this method is that a bigger contact area can be obtained between the two separated bone segments compared with that of sagittal split ramus osteotomy when the width of the mandibular ramus is narrow. In addition, it was suggested that a longer distance between the mandibular second molar and the anterior edge of the mandibular ramus could be a good indication for this operation.

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