Shika gakuho. Dental science reports最新文献

Measurement of the human substantia compacta and spongy bone. For the sake of a fuller understanding of the structure of the human mandible, a study was made to clarify objectively the thickness of the substantia compacta, the ratio of spongy bone to the total substantia spongiosa, and the width of the spongy bone. Subjects were 11 human mandibles from individuals ranging in age between 35 and 64. All teeth from the central incisor through the second molar remained in place. Measurement was performed with a personal-computer-based image-processing system. Results 1. Width of the substantia compacta Measurement of the width of the substantia compacta showed the thickest part (3.32-3.35 mm) to be roughly at the center of the lingual side of the incisors. The second thickest (2.85-2.90 mm) was located at the buccal-alveolar part of the molars. The thinnest (1.26-1.27 mm) part was located at the labial-alveolar part of the incisors. The next thinnest part (1.74-1.75 mm) was located at the central lingual portion of molars. In the mandible base, thicknesses at all locations fell in the range of 2.76-2.98 mm, with little location-related variation observed. In the labial(buccal)alveolar region, the substantia compacta grows thicker from the mental region toward the molars. In the central lingual region, it grows thinner from the mental region toward the molars. 2. Ratio of spongy bone to total substantia spongiosa Measurements showed the highest ratio (80.9-81.4%) of spongy bone to total substantia spongiosa to be in the lower lingual side of the incisors. This was followed by the central lingual portion of the mental region (80.36%) and the labial side and central regions of the incisors (69.71-78.36%). The ratio was lowest (29.79%) at the first and second premolars. In general, the ratio was high in the incisor region and low near the premolars. No difference was observed between the buccal and lingual sides of the incisor and premolar regions, although in the molar region, the ratio was relatively higher on the buccal than on the lingual side. 3. Width of the spongy bone within the substantia spongiosa.

In this study, peripheral circulatory responses during dental treatment under local anesthesia were observed. Changes in hemodynamics data, ECG, systolic blood pressure (SBP), diastolic blood pressure (DBP), digital and ear-lobe plethysmogram (PT), and radials and external carotid artery ultrasonic doppler blood flow (FW) were recorded by means of a multipurpose monitoring system. An improved fixed probe was devised for the purpose of stabilizing the external carotid artery FW record, and the ear-piece facebow system (Hanau, No. 153) was remodeled. Radial FW index D/S1 and external carotid FW index d/S1 were analyzed to determine systolic velocity S1 and diastolic velocity D or d. Pressure tests and cold stimulation tests were performed as fundamental research. Comparative investigations were made of changes in PT and FW in the light of SBP, DBP and heart rate (HR). A total of 71 instances of dental treatment was performed on 25 non-hypertensive patients (N-HT) and 25 patients with essential hypertension (HT). The patients were divided into 2 groups according to the local anesthetic employed: the E group, to whom 1:80,000 epinephrine with an addition of 2% lidocaine was administered, and the NE group, to whom 1:25,000 norepinephrine was administered. Results and conclusions 1. When peripheral blood flow was interrupted during the pressure test, digital PT and radial FW were disappeared. 2. Digital PT, radial diastolic FW D, and index D/S1 decreased greatly as a result of the cold stimulation test. It was suggested that changes in digital PT accord with the diastolic velocity D of radial FW. 3. At the stage of local anesthesia, SBP rose most in the HT-NE group. There was a tendency for digital PT and radial FW D either to decrease or to increase. It was assumed that cardio-stroke volume increased when PT and FW increased. Decreases in digital PT and radial FW apparently indicate increased capillary resistance. 4. Greatest increases in HR at the stage of local anesthesia occurred in the N-HT-E group. Digital PT and radial FW D tended to decrease. In cases of increased HR, PT and FW tended to decrease. In comparison with conditions immediately before treatment, digital PT and radial FW D decreased more in the N-HT group than in the HT group.

1. A statistical survey of oral-cancer (tongue, maxilla, and mandible) patients on which autopsies were performed by the 2nd. Department of Pathology of Tokyo Dental College from 1964 to 1987 was carried out. Of a total of 18 autopsies in cases in which death resulted from tongue carcinoma, 11 subjects were male and 7 female. Average age was 63.4 years. This cancer occurred most frequently in individuals in the age group of 60 to 69 years. The lung was the most common (50%) site of distant organic metastasis; the next most common sites were the liver, the thyroid gland, and the diaphragm (11.1% each). Submandibular and cervical lymph nodes were the most common sites of lymphatic metastasis in cases of tongue cancer. These data were similar to those in previous reports. 2. An autopsy on a 57-year-old man who died of tongue cancer revealed a number of distant metastases in both organs and lymph nodes were reported. 3. The report includes a review of literature on distant metastasis in cases of tongue cancer.

Zonogram investigations were made of 86 temporomandibular joints in 81 patients who were diagnosed by video-fluoroarthrogram as having anterior disc displacement without reduction. Comparisons between of condylar shape and movement, clinical phenomena, and disc perforation were made. Results 1. Condylar deformity on zonograms was classified into 3 types: flattening, osteophyte, and concavity. Condylar deformity was much higher in patients than in normal volunteer controls. 2. Condylar movement patterns were classified into 3 types: coordinated, uncoordinated, and limited. Coordinated movement was frequently observed in normal volunteers, and limited movement was common in the patients group. 3. In the patients group, condylar deformity was observed in both the displaced and the non-displaced sides, although it occurred with extremely high frequency in the displaced side. Condylar deformation was more common when the disc was perforated than when it was unperforated. A correlation between condyle deformity and pain on the non-displaced side was suggested; but no correlation existed between condylar deformity and such elements as age, joint sounds, mouth opening range, and locking term. 4. Limited condylar movement occurred more frequency in the displaced than in the non-displaced side. Consequently values for limited movement without joint sounds were high for the displaced side; and coordinated movement without joint sounds was frequent in the non-displaced side. There was no correlation between condylar movement and such elements as mouth opening range, locking term, and disc perforation. 5. Comparisons of condylar deformity and movement with clinical phenomena and disc perforation showed no instances of high (greater than or equal to 0.5) correlation. These results suggest that, in the temporomandibular joint, changes occur in both hard and soft tissues and that these changes take place on both the displaced and non-displaced sides.

Tail-vein injections of streptozotocin (STZ) in various doses (20-60 mg/kg body weight) were used to induce diabetes mellitus in male rats of the Sprague-Dawley strain. Resulting pathosis was observed on the basis of various parameters (body weight, blood glucose, plasma insulin, glucose-tolerance tests, uroscopy, hemodiagnosis, and skin strength) Results 1. Diabetes mellitus was induced in all rats of the group in which the dosage was STZ 40 mg/kg body weight (S-40 group). Blood-glucose level in this group was about 340 mg (3 times the quantity in controls). Plasma-insulin level was about 8.9 microU/ml (about 1/3 the quantity in controls). Glucose-tolerance tests and observation of urino-glucose showed reductions in glucose tolerance and plasma-insulin response. 2. In the S-40 group, pathosis of induced diabetes mellitus had stabilized 30 days after and persisted for 90 days after STZ injection. 3. Skin strength decreased for 20 days after STZ injection. The level remained stable at half the strength of control skin from 30 to 90 days after the injection. 4. In groups in which doses were STZ 20 mg/kg body weight or STZ 30 mg/kg body weight, diabetes mellitus was induced in some of the rats. The animals tended to recover from the induced pathosis. 5. Diabetes mellitus was induced in all rats to which doses of STZ 50 mg/kg or STZ60 mg/kg body weight were induced. shortly after injection, the induced-diabetes pathosis changed for the worse; and grave complications (hypo-albuminosis, diabetic ketocacidosis, and diabetic proteinuria) were observed. A large number of the rats in these groups died. 6. The results of this study confirm the opinion that STZ 40 mg/kg body weight is the optimum dose for STZ induction of diabetes mellitus in rats for experimental studies. The suitable term for such studies is from 30 to 90 days after STZ injection.

The mechanism of sodium fluoride (NaF) induced hypothermia was investigated on relations between the monoamine synthesis and metabolism in the rabbit brain. Five male rabbits per a group, weighing about 2.5kg and having rectal temperatures of 38.4 to 39.3 degrees C, were used in this experiment. The rectal temperature measurements were made by means of an electric thermometer for 5 hours at intervals of 15 or 30 minutes. Through this experiment, animals were housed in a room kept at 22 to 23 degrees C. The following drugs were used in this experiment: NaF (40 mg/kg i.v.), barbital sodium (0.1 g/kg s.c.), hexamethonium bromide (C6, 10 mg/kg i.v.), ergotamine tartrate (30 mg/kg s.c.), phenoxybenzamine hydrochloride (15 mg/kg i.v.), propranolol hydrochloride (5 mg/kg s.c.), pindolol (0.3 mg/kg s.c.), atropine sulfate (30 mg/kg s.c.), 2, 4-dinitrophenol (DNP, 20 mg/kg i.v.), l-DOPA (20 mg/kg i.v.), 5-HTP (20 mg/kg i.v.) Results 1. Intravenous injection of 30 mg/kg of NaF induced a drop of 0.66 degrees C in rectal temperature. 2. Pretreatment with 0.1 mg/kg of barbital sodium or 10 mg/kg of C6 prominently inhibited the NaF-induced hypothermia. 3. The alpha-blockade caused by ergotamine tartrate and phenoxybenzamine or the beta blockade by propranolol hydrochloride and pindolol resulted in an approximate 50% inhibition of maximum drop in body temperature induced by NaF administration. Both alpha- and beta-blockades caused by ergotamine tartrate and propranolol or by phenoxybenzamine and pindolol, however, made a remarkable inhibition of the NaF effect. Cholinergic blockade brought on by atropine sulfate, on the other hand, had no effect against NaF-induced hypothermia. 4. Bilateral splanchnicotomy completely inhibited drops in rectal temperature. 5. Intravenous injection of NaF 40 mg/kg failed to counteract the rise of rectal temperature caused by DNP 20 mg/kg. 6. Pretreatment with l-DOPA made a prominent inhibition of NaF-induced hypothermia. The inhibiting effects of 5-HTP, however, were slight. 7. Administration of NaF made a significant decrease in norepinephrine levels in the rabbit hypothalamus, but had no effect on 5-HT levels.

Recent developments in medical engineering has made it easy to record biological phenomena. Furthermore, the widespread popularity of the personal computer has made data processing system remarkably efficient. In this study, an efficient personal computer system for mandibular movement analysis is investigated, and a data analyzing system for that movement developed. Applying this system to chewing movements in a small number of cases made possible efficient, easy and accurate analysis. The following is an outline of the system and its applicability. 1. Standard measuring coordinate system for mandibular position and designation of mandibular position measuring point An orthogonal coordinate system is used to the standard measuring coordinate system for mandibular position measurement coordinates. The X axis of this orthogonal coordinate system is determined as a straight line connecting two LEDs. The origin point is designated as the center between two LEDs. This connects with the upper dentition or the maxilla. The mandibular position measuring point is designated on the orthogonal coordinate system. The X axis of this orthogonal coordinate system is determined as a straight line connecting two LEDs. The origin point is designated as the center between two LEDs. This connects with the lower dentition or the mandible. The analysis of mandibular position of designated measuring point on the lower dentition or the mandible is performed corresponding to the orthogonal coordinate system on the upper dentition or the maxilla. 2. Calculation of coordinates value [mm] for mandibular position measuring point In the analysis, value [V] for the distance between two LEDs established on the upper jaw is substituted for the already input real distance [mm] between two LEDs. The coordinates value of the mandibular position measuring point is calculated from these substitution value. 3. Data recording Data concerning mandibular movement and myoelectric discharges are recorded by means of a data recorder. Digital data are converted to analogue data from the data recorder by means of a 12-bit A/D converter and they are accumulated in the memory of the personal computer system. Digital data in the memory of the personal computer system can be stored in about 97 seconds for the storage capacity of a floppy disk (2HD) memory area.

Three-dimensional analysis by means of the finite element method was made of displacement and principal stress at various parts of plates and bone fragments. The plates were 4 Champy, AO, Luhr, Steinhäuser 4-hole, short miniplates (Plates 1,2,3, and 4) and Plate 5, which was the same as the others except that it was made of titanium. To all of these plates loads were applied in the directions of the Y and Z axes on the free(right)ends. The plates were fixed in place by means of screw holes 1 and 2 in the left ends. In addition, various kind of osteosynthesis were performed on 2 bone fragments with Plate 1. The left ends of these fragments were fixed in place, and loads were applied to the free(right)ends in the Y and Z axes. 1) When load was applied in the direction of the Y axis, displacements along the Y and X axes were greatest in the case of Plate 5 and next greatest in Plate 1. Displacement along the Z axis was greatest in Plate 3 and next greatest in Plate 5. Displacement along the X axis was least in Plate 3 and displacement along Y and Z axes were least in Plate 4. 2) When load was applied in the direction of the Z axis, displacements along the all axes were greatest in Plate 5, next greatest in Plate 1, and least in Plate 4. 3) In all plates, when load was applied in the direction of the Y axis, maximum principal stresses occured above the region between screw holes 2 and 3. Minimum principal stress, however, concentrated below the area between screw holes 2 and 3 in all models. 4) In all plate models, when loads was applied in the direction of the Z axis, maximum principal stresses concentrated in the outer central part of each plate in the region between the vicinity of the right edge of screw hole 2 and the vicinity of the left edge of screw hole 3. Minimum principal stress, on the outer hand, concentrated in the inner middle region of the plate in a zone corresponding to that in which maximum principal stress concentrated.(ABSTRACT TRUNCATED AT 400 WORDS)

Bone substitutes consisting in 2 mold-poured compound blocks of HAP:TCP (mixing ratio 1:1) and HAP:TCP (mixing ratio 3:1) and one compound block (mixing ratio 1:1) prepared in a rubber press were implanted in defective areas in rabbit mandibles. The conditions under which the implants were made were identical in all cases. Histological studies and contact microradiography performed on ossification of the surfaces and surroundings of each block, ossification maturation, and the absorptive process of TCP and the extent to which it was replaced by new bone produced the following results. 1. At one week after surgery, new bone had grown along the surfaces of the blocks. It remained in tight contact with the block surfaces as it matured. These findings make it clear that the blocks are superior in terms of biocompatibility and osteoconduction. 2. In the course of time, in the 2 mold-poured compound blocks, the hydrated parts of alpha-TCP, which was a binder, were absorbed and replaced by new bone. At forty eight weeks after surgery, new bone had grown into the pores of the HAP particles to form a bone-HAP composite. 3. Even as late as forty eight weeks after surgery, some of the hydrated parts of alpha-TCP remained unabsorbed; and mold-poured compound blocks (mixing ratio 1:1) retained their shapes. On the other hand, in the mold-poured compound blocks (mixing ratio 3:1), the hydrated parts of alpha-TCP were almost absorbed and replaced by new bone in forty eight weeks after surgery. Amounts of the binder alpha-TCP present appeared to cause differences in biological reactions. 4. In the case of compound blocks of HAP:TCP (mixing ratio 1:1) formed in a rubber press, the binder was beta-TCP. Because of its high sintering properties and great density, absorption and ossification were gradual; and the blocks retained their complete original forms even in forty eight weeks after surgery. 5. Past reports have claimed that beta-TCP is absorbed in the initial stage. But, as is clear from experiments with compound blocks formed by means of a rubber press, even when the binder is beta-TCP in all cases, absorption speed differs depending on the mold used. 6. These results indicate that compound blocks of HAP and TCP used as artificial substitute bone materials have excellent properties of biocompatibility, osteoconduction, and plasticity. In addition, however, they make it clear that, owing to differences in absorption of the binder, ossification speed, and dynamic properties from block to block, it is essential to use the mold that properly suits conditions prevailing in the defective area.