Hitoshi Sasakura

Impairment of the inferior alveolar nerve after sagittal split osteotomy.

The incidence and degree of neurosensory disturbance of the inferior alveolar nerve, as well as its recovery course, were studied on 46 sides in 23 patients who had undergone bilateral sagittal split osteotomies, by means of subjective symptoms, light touch, anaesthesiometer and two-point discrimination. The degree of disturbance was classified into mild, moderate and severe grades by the threshold pressure shown in tests with the anaesthesiometer. The disturbance, which was almost exclusively limited to mild (37%) and severe (28%) grades, was observed in 67% of the sample at one week. The disturbance disappeared completely within one to three months postoperatively in most sites with mild disturbance, and within three months to one year in half of the severely affected sites. Although the recovery was delayed in the other half of the severely disturbed sites, the disturbance was of mild grade at one and a half years. The overall incidence of disturbance at one year was 15%. Computed tomographic examination of the ascending ramus showed that the narrowest width between the mandibular canal and the buccal cortical plate ranged from 0 mm to 3.2 mm with a mean of 1.6 +/- 0.9 mm (SD) and it was less than 1.2 mm in 91% of sites with a severe grade disturbance, whereas it was distributed in a range of 0.9 mm to 3.2 mm in sites with no disturbance or with mild or moderate disturbance. The importance of preoperative computed tomography to indicate the location of the mandibular canal and the use of a thin cement spatula for the osteotomy was stressed, to avoid or reduce postoperative development of neurosensory impairment.

Root resorption of upper permanent incisor caused by impacted canine. An analysis of 23 cases.

Unusual root resorption of 12 central and 11 lateral upper permanent incisors in 11 patients is described. The degree of resorption ranged from loss of the apical 1/4 to almost complete loss of root structure. Excepting 1 case, permanent canines were partially or completely impacted and their crowns were in close apposition to the resorbed surfaces of the incisors. The roots of the canines were either in the process of formation or completely formed. The findings suggest that the pressure from the canine which persists in moving downward despite the lack of space to permit normal eruption could cause root resorption of adjacent incisors even in the absence of systemic factors. Of 14 extracted incisors, 10 were replaced orthodontically by the impacted canines, whereas the spaces of the extracted incisors were restored by prosthetic means in the 4 other cases. 6 incisors were preserved without any treatment and 2 with the aid of a sapphire dento-osseous anchor pin. Since the resorbed incisors were mostly free of pain, early detection by radiographic examination is essential to establish a proper diagnosis.

Three-dimensional analysis of facial morphology before and after orthognathic surgery

A method for three-dimensional analysis of the facial hard- and soft-tissue morphologies is described. The soft-tissue analysis consisted of calculating three-dimensional values of reference points on the face by perspective transformation of their values in two pairs of photographs, taken simultaneously, from the right and left sides of the face. The shape of the mandible was analyzed three-dimensionally by the simultaneously taken frontal and lateral cephalograms. The hard- and soft-tissue changes were analyzed with the method in 28 patients in whom mandibular prognathism had been corrected by orthognathic surgery. The magnitude of the surgically-produced soft tissue volumetric changes in the anterior mandibular region was proportional to the posterior movement of the mandible. Asymmetry of the face also improved in response to correction of lateral deviation of the mandible and a close correlation between the directional indices of asymmetry of the hard and soft tissues was observed. Thus, the method was found to be quite useful for the analysis of facial morphology in jaw deformity.

Three-dimensional prediction of mandibular movement in the treatment of prognathism

The three-dimensional movements of the mandible that might occur during surgical correction of mandibular prognathism were analyzed preoperatively in 40 patients. Direct measurements were made on the dental models used to predict postoperative occlusion, and the results were transferred to the cephalometric tracings using three-dimensional coordinate transformation. Menton, gonion, and two bony points on the posterior borders of the ascending rami were chosen on the frontal and lateral cephalograms for prediction of the antero-posterior, vertical, and lateral movements. In most cases a reasonable amount of movement without much lateral shift at the posterior border of the mandible was predicted to occur when the postoperative position of the mandible was established to provide a stable occlusion. However, there were five cases in which predicted lateral movement at one of the posterior borders exceeded 5 mm, and, in four of them, protrusion of the mandible was not accompanied by lateral deviation. It was concluded that careful preoperative planning and postoperative treatment are necessary in these cases because a large amount of lateral movement at the site of operation might lead to postoperative relapse following ramus osteotomy.

Severe Facial Asymmetry Treated by Two Jaw Surgery and Hydroxylapatite Block Graft; Report of Two Cases

Two cases of severe facial asymmetry resulting from progressive facial hemiatrophy and hemifacial microsomia treated by two jaw surgery and hydroxylapatite (HA) block graft are reported. Both cases had a similar three-dimensional jaw deformity. Two jaw surgeries were performed to improve the occlusal plane inclination and the asymmetric contour of the mandible. HA blocks which were made from wax models on the mandible models reconstructed from CT, were grafted to improve the remaining deformity. Various problems associated with the procedures are discussed.

Effects of orthodontic and periodontic therapy on periodontal health in children with the malposed anteriors.

前歯部歯列不正を有する若年者10名の矯正-歯周治療効果を3+3, あるいは3+3の18部位の歯肉溝滲出液 (以下GCF) をマーカーとしてその中のcollagen破壊酵素のcollagenase活性, 炎症のマーカーとしてのacid, alkaline phosphatase活性を測定し判定した。歯列不正歯の歯肉溝中の炎症細胞数と歯周組織の炎症との関連についても検討し以下の結果を得た。歯周治療前の総GCFはPeriotron値で1, 147±412であったが, 初期治療後は328±97となり, メインテナンスを続けた結果, 256±133となり有意に減少した。GCF中のcollagenase活性は, 歯周治療前43, 457±22, 934 (cpm, Mean±S.D.) であったものが初期治療後13, 302±6, 125と有意に減少しメインテナンス期にも低い活性を維持していた。collagenaseには活性型と潜在型があり, 初期治療前には活性型と潜在型のタンパクあたりの活性には差は見られなかった。メインテナンス期には活性型collagenaseのタンパクあたりの活性は初診時と有意差はなく, 潜在型collagenaseの活性は有意に上昇した。acid phosphataseの活性は歯周初期治療後およびメインテナンス期には初診時の18%, 10%にそれぞれ下がりalkaline phosphataseの活性はメインテナンス期には初診時の18%のレベルまで低下した。白血球数は初期治療後, メインテナンス期で初診時の30%以下になった。臨床的パラメーターに関しては, Gingival Index, Plaque Index, Gingival Bleeding Index, pocket depthともに有意な改善が認められた。

Xerox copy of the dental cast for analysis of the stability of mandibular osteotomy

Stability of the mandible was analysed with a Xerox copy of the dental cast in 35 cases of mandibular prognathism corrected by ramus osteotomies. The occlusal relationship in the Xerox copy was illustrated by superimposing two contact points on the upper and lower dental arches and the change in the position of the lower dental arch in relation to the upper dental arch was obtained by superimposing the latter on preoperative, predicted postoperative, and six months postoperative occlusions. The stability of the mandible was analysed by measuring the movement of five landmarks (two posterior, two molar and one incisor points) set around the lower dental arch to represent the movement of the mandible. The relapse was estimated by the movements of the landmarks from the predicted postoperative occlusion to the six months postoperative occlusion. The mean estimated anterior relapses at the posterior and molar points with the larger predicted movement and the incisor point were between 0.9 mm. and 2.0 mm. at six months postoperatively, whereas on the side with the smaller predicted movement, the points moved posteriorly by 0.6 mm. and 0.5 mm. Despite the fact that the amount of the predicted lateral movement was much smaller than that of the predicted posterior movement at operation, the posterior points were estimated to relapse laterally by 2.0 mm. and 1.7 mm.(ABSTRACT TRUNCATED AT 250 WORDS)