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)

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.

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.

Screw-type mouth gag for prevention and treatment of postoperative jaw limitation by fibrous tissue.

Treatment of a severe tethering of the mandible by surgery and subsequent exercise of the jaw with a newly devised mouth gag, consisting of two blocks of acrylic resin with a screw expander between them, is described. The mandible was gradually forced to open and was retained in the opened position by rotating the screw against the resistance of scar contraction without much pain. Possible development of trismus after excision of a tumor in the lower retromolar area because of surgical injury to the medial pterygoid muscle and postoperative scarring was avoided by means of the appliance.

[A long-term study on dentofacial changes after sagittal splitting osteotomies in skeletal Class III malocclusions].

The purpose of this study is to clarify the long-term dentofacial changes after sagittal splitting ramus osteotomy in skeletal Class III patients, and to study the factors involved to find its countermeasures. For this purpose we used the radiographic cephalograms in 16 patients (13 females and 3 males) observed for more than five years after surgery. We measured the postoperative changes in the position of Pogonion and the inclination of maxillary and mandibular incisors. The results were as follows: 1. Pogonion was retruded 9.3 mm on the average by surgery. In the period from the removal of intermaxillary fixation to one year postoperatively Pogonion slipped forwardly and upwardly (average; anteriorly 1.0 mm, superiorly 0.8 mm). In the period from one year postoperatively to the time of the final observation Pogonion slipped to a downward direction. 2. No correlation was found between the amounts of vertical displacement by surgery and postoperative vertical changes of Pogonion. On the other hand, a high correlation was found between the amounts of mandibular setback and the forward displacement of Pogonion. 3. Mandibular incisors were tipped labially by preoperative orthodontic treatments, then maxillary and mandibular incisors moved lingually during intermaxillary fixation. After release of intermaxillary fixation, maxillary incisors moved labially in a small distance. After one year maxillary incisors were inclined slightly in the lingual direction. It is obvious that the position of the mandible and the incisor inclination tend to change even after one year. Because the postoperative changes were small in quantity, we supposed they were mostly caused by occlusal changes. Clinically, occlusal relationship in the incisor area, i.e., overjet and overbite, was maintained to be normal. It was considered that the changes of incisal inclination after release of intermaxillary fixation were of a compensatory or adaptational response to a positional change of the mandible.

A fluoroimmunoassay based on immunoliposomes containing genetically engineered lipid-tagged antibody.

Immunoliposomes were prepared by using biosynthetically lipid-tagged anti-2-phenyloxazolone single-chain antibody. Carboxyfluorescein as a fluorescent marker was encapsulated in the immunoliposomes. Some conditions for fluoroimmunoassay using the immunoliposomes were optimized by binding assays with hapten-coated microtiter wells. A competitive fluoroimmunoassay for the caproic acid conjugate of 2-phenyloxazolone as a model antigen was performed with the immunoliposomes. In the optimized assay conditions, antigen could be determined in the concentration range from 10(-7) to 10(-9) M.

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 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.