Nihon Kyosei Shika Gakkai zasshi = The journal of Japan Orthodontic Society最新文献

Basilar impression is one of bony deformities occurred in the region of the foramen magnum, in which deformity, rim of the foramen magnum or a part of the vertebra impresses into the posterior cranial fossa. Major symptoms of this deformity are short neck, low hair line, torticollis, webbing of neck, pain and limitation of neck movement and various nerve symptoms, when nervous tissue is impressed by rim of the foramen magnum or dens of the second vertebra. This deformity has a characteristic to be found later as a congenital deformity, because nerve symptoms usually do not occur in earlier than 10 years old. The patient was 7 years and 8 months old at his initial visit, whose chief complaint was rotation of upper central incisors which created chewing disorder. When he became 12 years old, because he was taken palsy, walking disturbance, and neck pain in movement, neurosurgery was planned immediately. Edgewise appliance was, then, removed, and orthodontic treatment had to be discontinued until he left hospital. A case was reported of the problems in orthodontic treatment and characteristic of this deformity through our experience for this cleft lip and palate patient with basilar impression in addition to other reports about this deformity.

To elucidate the histological and histochemical changes on the deep layer of masseter muscle at the site of their attachment to the mandible after masseteric denervation, 35-day old male rats were used in this experiment. The rats were sacrificed at 10 and 20 days after the left masseteric nerve was resected at the mandibular notch. The attachment of deep layer of masseter muscle to the mandible was examined using light microscopy, lead labelling technique (Okada and Mimura 1938), and histochemical analysis for ALPase activity. Electromyographic techniques were used for detecting masseter muscle function. 1. 10 days after denervation, the number, shape and ALPase activities of osteoblasts in the transitional zone and fibrocartilage cells in the tendinous attachment on the operated side were seen to decrease compared with those in control. Bone formation on the operated side was less than that in control. The electrophysical activity of masseter muscle was not detected on the operated side. 2. 20 days after surgery, ALPase activities of osteoblasts and fibrocartilage cells, and bone formation in the transitional zone and tendinous attachment on the operated side increased, compared with those observed in the same area on the operated side in the 10-day group, but still less than those in control. Low levels of electrophysical activity in masseter muscle were detected on the operated side. 3. In the periosteal attachment and inferior surface of the mandible on the operated side, bone formation was also seen to be less than that in control. These results suggested that the function of masseter muscle seems to exert the greatest influence on the proliferation and differentiation of both fibrocartilage cells and osteoblasts, and bone growth in the attachment of masseter muscle.

The present investigation has been attempted to clarify the remodeling mechanisms of transseptal fibers during mechanical retention periods. Orthodontic forces of 25 gm and 150 gm were respectively applied to upper molars of rats for 10 days and retained mechanically. Retention periods were 10, 30 and 60 days. The trend of transseptal fibers after these retention periods was observed by the methods of histology and histochemistry. Histological study was observed rearrangement of fibrous tissue by light and electron microscopy and histochemical one was observed acid phosphatase activity. The following results were obtained: 1. Very little was observed about the rearrangement of transseptal fibers by the orthodontic force applied for 10 days. 2. The mechanical retention was kept longer, stretched transseptal fibers were slowly restored to original shape. This means transseptal fibers were gradually rearranged. 3. The collagen containing fibroblast and fibroblast characterized by abundant rough endoplasmic reticulum and Golgi complex were ultrastructurally observed. 4. The reaction of ACPase activity in some fibroblasts can be observed. These results suggest that transseptal fibers were rearranged during mechanical retention periods and that fibroblasts were engaged in this remodeling by synthesizing and degrading collagen fibers.

The role of mechanical stress in determining bone structure by influencing its cellular processes during remodeling has been discussed. But previous studies have not provided an adequate background of knowledge to explain the effect of orthodontic force in internal remodeling of the bones. This study was performed to determine the relationship between stress distribution induced by orthodontic force and alteration of internal remodeling in mandibular bone. Seven young adult mongrel dogs of unknown age were used as experimental animals. The bilateral lower 4th premolars were extracted. After 106 days, the 3rd premolars on the right side were moved distally by coil springs for 106 days. Twice pulse labels of tetracycline and calcein were performed to obtain histomorphometric parameters of cortical bones prior and posterior to tooth movement. With the use of microscopic plotting tool and minicomputer, the direction of haversian systems was reconstructed three-dimensionally. To make a comparison with the alteration of histomorphometric parameters and direction of Haversian systems, the principal stress distribution of mandibular bone caused by orthodontic force was obtained by means of 3-D finite element method analysis. Experimental results indicate as follows. 1. The osteoid seams number per unit area (OsAf) and the labeled surface per unit area (TcAf) increased significantly at both alveolar and basal bone region compared with control side. 2. The resorption cavities number per unit area, (Ar) increased significantly at alveolar bone region. But no significant changes were noted at basal bone region. 3. No significant differentiations were noted in mineral appositional rate (Mo) between any bone regions nor label timings. 4. There is large variance between the direction of Haversian systems and the maximal principal stress vector. But a significant alteration of the direction of Haversian systems was found in highly stressed and younger bone areas. From these findings, it can be speculated that, as a primary reaction of bone against stress, the optimum microscopic structural change took place in areas of bone which bore tension or pressure due to excess stress, at the same time the internal remodeling of bone was accelerated by increase of activation frequency (mu), accompanied with no increase of remodeling periods (sigma).

The influence of properties of the diets on the retardation of growth of the jaw bones and masticatory muscles has been established. As the intake of liquid foodstuffs increases in the human diet, it is considered possible that these liquid diets may retard the growth of human salivary glands. 180 newborn C3H/He strain male mice were divided into solid and liquid diet groups and then the development and aging of the submandibular glands were observed both in function and morphologically until 60 weeks of age. The following results were obtained: 1. No differences could be detected in body length and body weight of the mice between solid and liquid diet groups. The wet weight of the liver in the liquid diet group was significantly larger than the solid diet group, which suggested that the liquid diet may have accelerated metabolic functions. Additionally, masticatory muscles of the liquid diet group were significantly smaller than the solid diet group which suggested growth retardation of the masticatory organ. 2. The submandibular gland wet weight and its DNA content in the liquid diet group were lower than in the solid diet group during the experimental period. This suggested that the number of cells and their ability to divide was diminished. The wet weight of glands per unit DNA content showed an increase in cell size during the adult period. 3. The alpha-amylase activity and total protein content of the submandibular glands in the liquid diet group were lower than in the solid diet group. This suggested that the saliva secretory function and protein synthesis were depressed, in agreement with the low number of cells detected. 4. The differentiation of the acinar cells and convoluted tubule cells of the liquid diet group was retarded and the 60 weeks subgroup showed hypertrophy of the convoluted tubule cells, disappearance of the secretory granules and a decrease in the number of acinar cells. 5. Slight stromal fibrosis was observed with increasing age (60 weeks) with no difference between the two groups. 6. This suggested that when mice were fed a liquid diet, the development of salivary glands was retarded and also aging changes occurred more rapidly.

The study was undertaken to investigate the individual growth timing of the mandible during late adolescent period. Materials used in this study were lateral cephalometric X-rays, hand bones X-rays, panorama X-rays and data of standing height of eighteen Skeletal Class I Japanese boys, all were longitudinally taken from 15 to 18 years old. Results were as follows: 1. Mandibular growth was continued to increase until 18 years old, but annual growth rate was decreased every year. 2. Growth increments of mandibular length was widely varied during 15 to 18 years old. 3. Ossification timing of MP3u and R-IJ stage were tended to delay in cases, represented large amount of growth. 4. Cases showing large amount of growth in the mandible tended to have large increments in body height. 5. There was less correlation between mandibular growth timing and maturation of lower third molars. In conclusion, the growth behavior of hand bones and body height could be used as indicators for predicting mandibular growth potentiality during late adolescent period.

Three orthodontically treated cases with sounds of the temporomandibular joint are presented. Case 1: Eight months after [formula: see text] extraction, bilateral TMJ sounds were noticed. The patient had a history of pre-orthodontic TMJ sounds and locking. A disc recapturing splint was therefore set on the upper arch, then changed into a stabilization splint for 5 months. The TMJ sounds faded away and the active treatment was completed. Case 2: The patient had [formula: see text] missing teeth, severe deep bite, upper and lower spaced arches. She also had mild facial deformity and bilateral TMJ sounds. TMJ arthroscopy showed right side "Anterior disk displacement without reduction" and left side "Anterior disk displacement with reduction". Maxillary spaces were closed following standard splint therapy. Right side TMJ sound diminished considerably while left side sound faded away completely. Finally, prosthodontic treatment was performed. Case 3: The patient had mandibular right side shifting, upper and lower crowding and a right side TMJ sound. Initially, maxillary lateral expansion was performed using a Quad-helix appliance. Simultaneously a positioner-type splint was used on the lower arch for avoiding any occlusal interference. TMJ sound faded away and a standard [formula: see text] extraction treatment was completed for crowding correction and better occlusion.

To investigate the effects on perioral muscles with mechanical stimulation to the mucosa electromyograms were recorded in nine subjects. Results were as follows: 1. Tonic excitatory reflex of m. orbicularis oris and m. mentalis was evoked by the non-painful pressure stimulation to lower lip mucosa. These responses were increased, as the stimulus strength was increased. 2. Reflex responses to stimulation of the corner of the mouth and lower lip mucosa were greater than that of buccal mucosa. The response in m. orbicularis oris superior (O.O.S.) to stimulation of upper lip mucosa was greater than in m. orbicularis oris inferior (O.O.I.). And the response in O.O.I. to stimulation of lower lip mucosa was greater than the response in O.O.S. 3. Tonic excitatory reflex was abolished after local anesthesia of the stimulation area. 4. Excitatory reflex was reversed to inhibitory reflex, when background activity of three muscles was changed by voluntary lip closure. When background activity was weak, excitatory reflex was induced by pressure stimulation. On the contrary, when background activity was strong, inhibitory reflex was induced by the same stimulation. When background activity was moderate, excitatory reflex in O.O.I. and inhibitory one in O.O.S. was easily induced by lower lip stimulation. On the other hand, by upper stimulation, excitatory reflex in O.O.S. and inhibitory one in O.O.I. was easily induced. These results suggest that the orthodontic appliance placed on the vestibular oris gives mechanical stimulation to oral mucosa, which induce reflex contraction in perioral muscles.

In an orthodontic point of view, it is said that necrotic tissues cause a standstill of tooth movement until they disappear and that term of the standstill is related to the size of the necrotic tissues. Although remodeling processes of a periodontal membrane in compressed area were reported as series of phenomena like degeneration, coagulative necrosis, calcification and histiolysis, there is no direct evidence that the necrotic tissue is really calcified. The purpose of this study is to clarify histologically whether the necrotic tissues in the periodontal membrane are calcified or not and to know when appearance and disappearance of the calcification occur during an experimental tooth movement. Twenty eight rats were used for this study. For the experimental tooth movement, the orthodontic elastics were inserted into the interproximal space between the maxillary right 1st and 2nd molars during 1, 2, 3, 5, 7 and 14 days respectively (Waldo's method). The periodontal tissues were observed on undecalcified sections by vital staining in which oxytetracycline (3 mg/kg), alizarin red (8 mg/kg) and calcein (0.8 mg/kg) were applied as well as by contact micro radiography (CMR). Findings were as follows: 1) After 2 days of tooth movement, a part of the periodontal membrane in compressed area showed fluorescence by vital staining and was radiopaque by CMR. This means that the necrotic tissues are really calcified at least after 2 days of experimental tooth movement. 2) After 7-14 days no calcified tissue could be found in the periodontal membrane. The calcified tissues may disappear under processes of resorption in this area.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of this study was to investigate the functional changes following the orthodontic treatment of anterior reversed occlusion in children. Samples consist of 94 children with anterior reversed occlusion as the experimental group and 34 children with normal incisor occlusion as the control group. Experimental samples were classified into 3 groups according to the erupting stages of incisors. Among them, a group of the permanent incisor dentition was divided into 2 groups, one was a "Shift group" showing functional mandibular movement from the centric relation to intercuspal position and the other was a "non-shift group" showing no such functional movement. In the experimental group, 28 patients showed the correction of anterior reversed occlusion orthodontically. Mandibular movements were recorded during gum chewing on all subjects by using Sirognatho Analysing System II. Mandibular movement was examined as to the cycle time and the chewing movement on the horizontal plane. The results were as follows: 1. The chewing cycle was irregular in samples of reversed occlusion. 2. Samples of reversed occlusion with deciduous incisors and of normal occlusion were equivalent in the cycle time. 3. The chewing cycle was more longer in samples of reversed occlusion with maxillary deciduous and mandibular permanent incisors than those of normal occlusion. 4. The chewing cycle was longer in the Shift group than in the normal group. But it was not longer in the Non-shift group than in the normal group. 5. The chewing movement of the Shift group showed type-1, 2, 3 rather than type 4. But the non-shift group showed type-4 more than type-1, 2, 3. 6. The chewing cycle became more regularized after the correction of anterior reversed occlusion. 7. The chewing cycle was shortened in the Shift group after the correction of anterior reversed occlusion. 8. The chewing movement of type-1 and type-4 were decreased after the correction of anterior reversed occlusion. In conclusion, the correction of anterior reversed occlusion by orthodontic method provides improvements of not only the morphological incisor occlusion but also the functional mandibular movements.