The purpose of this study is to clarify the acoustical characteristics of the occlusal sound. An FFT analyzer was used to analyze the transfer functions of the oral cavities. The characteristics of the waveform of the occlusal sound were investigated by the time-frequency analysis. The results obtained were as follows: (1) There were three peaks in the low frequency area of the transfer functions of the oral cavities. The duration of the impulse responses of the oral cavities had a wide variation among the individuals. (2) The waveform of the occlusal sound by air-conduction was proved to consist of two components. One was the teeth collision sound produced by the collision of the teeth in the oral cavity and emitted directly out from the oral cavity. The other was the reverberation considered to be formed mainly by the resonance system in the oral cavity. (3) By the time-frequency analysis, the teeth collision sound could be distinguished clearly from the reverberation ; the former was recognized as the component where the energy existed up to the high frequency area, while the latter was recognized as the component where the energy existed only in the low frequency area. (4) It was suggested that the teeth collision sound, after separating from the reverberation, should be analyzed for the purpose of obtaining further information about the functional condition of the occlusion from the occlusal sound.
This is a report on the statistical classification of the prosthetic restorations placed in outpatients of the Tokyo Medical and Dental University Hospital. The data were collected from the laboratory records during the period of January to June of 1986. The results are summarized as follows: 1. The total number of the prosthetic restorations placed in the outpatients were 7355, and 56% of these were covered by the health insurance. 2. Of the total restorations, 29.6% were cast cores, 18.2% were inlays and 17.2% were crowns. Post crowns, jacket crowns and partial veneer crowns were very few, being only 0.3%, 0.4% and 0.5%, respectively. 3. Approximately 50% of the prosthetic restorations were single crowns. 4. Compared to the record from about 20 years ago, the number as well as the ratio of the crowns including the facing crowns was approximately doubled. On the contrary, the number of jacket and post crowns has remarkably decreased. 5. With regard to the single anterior prosthetic restorations, the majority were the porcelain fused to metal crowns which were not popular 20 years ago.
Ni-Ti alloy compression mini-plate was developed for rigid bone-fixation in oral surgery. The investigation of the mechanical properties of this plate was performed to obtain basic data for its clinical application. Ni-49.49 Ti (at%) alloy and Ni-49.26 Ti (at%) alloy were used for the specimens. First, transformation temperatures of the alloys were measured to evaluate the effect of heat-treatment temperatures. Secondly, tensile and shape recovery tests were performed on four types of mini-plates, i. e., four-hole regular and long types Ni-49.49 Ti (at%), five-hole regular type Ni-49.49 Ti (at%) and Ni-49.26 Ti (at%) . The following results were obtained. 1. Specimens with a heat-treatment at 500.., for 30 minutes in both compositions showed adequate As points (about 25..) and Af points (44. `50..) for clinical use. 2. In the tensile and shape recovery tests, the 500.. heat-treated four-hole regular type plate showed better mechanical properties than the 440.. heat-treated one. However in the four-hole regular type plate without heat-treatment, the shape memory effect was rarely found. 3. The five-hole regular type plate of Ni-49. 49 Ti (at%) alloy had the best mechanical properties for clinical application, judging from the amount and the temperature of shape recovery. It is concluded that Ni-Ti shape memory alloy mini-plates should be applied for rigid internal bone-fixation in oral surgery.
The purpose of this study is to investigate the viscoelastic properties of the oral mucosa. The handy apparatus which can easily show the rheological properties (i. e., G′, G′, tan . A) was made for the trial. The principle of this apparatus is to measure the stress and the phase difference produced when the constant sinusoidally oscillating shear deformation is loaded on the viscoelastic materials. This handy trial apparatus was found to be applicable in vivo, as evaluated by the dynamic spectrometers. The viscoelastic properties of the mucosa of the maxilla were investigated with this apparatus. The results were as follows: 1) Viscoelastic values varied in individual cases. 2) In the maxillary ridge area and the median portion, the values of modulus G and tan a were low. In other words, the stiffness of these areas was low and the recovery from deformation was fast. 3) The values of modulus G and tan δ were high in the side region of the palate. The result showed that in this area there was a high stiffness and the recovery from deformation was slow. 4) In the incisive papilla and the area of flabby gum, the values of modulus G were low and the values of tan δ were high. The low stiffness and the slow recovery from deformation were shown in these areas.
The purpose of this study was to determine the genetic control of the primary antibody response of inbred strains of mice against sonicated extract from Actinobacillus actinomycetemcomitans, a representative periodontal pathogen. Three groups of inbred mice strains, six independent strains, six H-2 congenic strains (B10 (H-2b), B10. A (H-2a), B10. BR (H-2k), B10. D2 (H-2d), A/J (H-2a), A. BY (H-2b) ) and four intra-H-2 recombinant strains (B10 (Kb, I-Ak, I-E-, Db), B10. A (4R) (Kk, I-Ak, I-Eb, Db), B10. A (5R) (Kb, I-Ab, I-Ek, Dd), B10. MBR (Kb, I-Ak, I-Ek, Dq) ) were examined on the basis of serum antibody titers to A. actinomycetemcomitans by the ELISA and of the band appearance by Western blot analysis. The levels of antibody titers varied within the first group and between A/J (H-2a) and A. BY (H-2b) in the second group. Western blot analysis showed two kinds of bands: a) constant bands appearing in all strains and b) specific bands appearing only in the distinct groups of strains. One of the latter kind of band, at 65kDa, was unique to the H-2b strains (B10, B6, A. BY) in the first and second groups and the I-Ab strains (B10 and B10. A (5R) ) in the third group. These results indicated that the immune response to some antigens of A. actinomycetemcomitans was influenced by the genetic background, and the immune response to some of these, such as the 65kDa antigen, was controlled by the gene in the H-2 complex.
At the Hiraizumi Primary School in Iwate Prefecture, 84 children with incipient gingivitis were selected at the annual dental examination in May. And the teachers instructed these children individually how to remove the remaining dental plaque. Moreover, the children were checked for the cleanliness of the teeth and inflammation of the gingiva by the teacher or their parents three times a day during the one week just before the second examination. In July the second examination was held and it was revealed that in sixty-three of eightyfour selected children the incipient inflammation of gingiva had improved.
The influences of experimental balancing-side interference on the jaw function were investigated on 6 subjects. A specially designed onlay was fabricated for the lower second molar, which acted as an artificial balancing-side interference in the lateral mandibular position. The subjects were asked to do maximum clenching, lateral gliding and gum chewing with and without the device. Electromyographic activity of the masseter and the anterior and posterior temporal muscles were measured and the related mandibular movement was simultaneously recorded during these tasks. Introduction of the experimental interference caused alteration in the muscle activity as follows: 1. When the subjects exerted maximum clenching efforts in the lateral mandibular position, the ratio of the temporal muscle activity on the working-side to the balancing-side decreased, while that of the masseter muscle remained unchanged. 2. There was a tendency for the activity in the working-side posterior temporal muscle to increase during gliding from intercuspation. The ratio of the temporal muscle activity on the working-side to the balancing-side decreased during gliding into intercuspation. 3. Prolongation of the occlusal phase associated with the increase of the muscle activity was observed during gum chewing on the side opposite to the interference. It was suggested that the balancing-side interference might provoke a specific muscle activity in the temporal muscles during parafunctional clenching or grinding.
The characteristics of occlusal facets are important criteria used in the functional assessment of the stomatognathic system. A new system of optically quantifying the facets using a graphic image-processor has been developed, which makes it possible to measure the area and the inclination angles of each facet in the frontal and sagittal sections. In this study, the occlusal facets were investigated in 5 cases with normal dentition concerning the inclinations, areas, locations and occlusal contacts. The facets which made contact with their opposing ones in the intercuspal and lateral occlusal positions were selectively analyzed. The frontal inclination angles of the facets increased or decreased according to their mesio-distal locations in the working-facet or balancing-facet series, respectively. The sagittal ones indicated that most of the facets on the lateral excursion belonged to either the mesial or distal slopes of the cusps in each case. The angles made by the upper and lower facets which made contact were greater in the lateral occlusal positions than in the intercuspal position. Most of the areas of the upper facets were larger than those of the lower ones, which fact was remarkable on the facets related to the occlusal contacts between the intercuspal position and the cusp-to-cusp positions of the canines.
The mechanism of bone remodeling has been investigated by many researchers. However, little is known about the role of the local factors which exist in the bone matrix. In this study, the author attempted to purify the bone-resorbing factor from the bovine bone matrix and to find its role in bone remodeling. The demineralized bovine bone matrix was extracted with 4M Gdn-HC1 and the boneresorbing factor was purified by means of heparin affinity and gel filtration chromatography. The analysis of bone resorption was carried out by the measurement of the released 45Ca from the pre-labeled mouse calvariae. The results of this study were that the bone-resorbing factor in the bone matrix was suggested to be a heat-stable glycoprotein having a molecular size higher than 150, 000, which stimulated osteoclastic bone resorption via a prostaglandin-mediated mechanism.
The purpose of this study was to investigate the factors influencing the masticatory function and proper test foods for the evaluation of the masticatory ability of complete denture wearers. One hundred and forty-five edentulous patients participated in this study. The basal seat area, the present and new dentures and the maximal bite force of each patient were divided into several sections and scored. The masticatory ability of the patients was evaluated by the questionnaire on the masticatory aspects of 100 foods. The following conclusions were drawn from the data: 1. The score of the basal seat area, the quality of the dentures and the maximal bite force were associated with the masticatory ability. 2. The masticatory ability of the fifties were higher significantry than the other age groups. 3. The change of the masticatory ability when the patients wore new dentures was small in the fifties and the eighties. 4. The rate of change of the masticatory function between the present dentures and the new dentures was associated with the physical properties of foods.
In order to evaluate the possibility of dental implant applications of glass-ceramics (GC), an implant study using rat femurs was performed. This GC contains crystalline apatite, wollastonite and diopside in a CaO-P2O5-Mg0-Si02-CaF2 glassy matrix. The cylindrical GC were implanted in the drilled holes of the femurs and the histologic reactions to the GC and the crystallographic changes of the GC were investigated at the timed sequence for one year. The GC provoked the endosteal bone formation. The intervening fibrous tissue between the encapsulating bone and the GC was replaced by bone tissue which was outgrowing from the encapsulating bone surface. Finally, the interface between them was bonded. The surface layer of the GC was changed morphologically and crystallographically. During these bonding phenomena, the X-ray intensities of Ca, P, Si and Mg and the crystalline pattern of the apatite crystal in this reactive zone changed. These changes might be closely related to the bone-bonding between the encapsulating bone and the GC. These results indicate the excellent biocompatibility of the GC and suggest the effective clinical application of the GC as a dental implant.
The newly developed fluoride-releasing sealant (F+sealant) used in this experiment is expected to have the combined cariostatic effects of a sealant and fluoride. The purpose of this study was to investigate F+sealant's effects on the enamel in regard to the uptake of fluoride and resistance to acid. F +sealant's effect was compared to that of acid phosphate fluoride (APF) which has effect as topical fluoride applicant. Bovine teeth applied with F+sealant or APF were immersed for 4 weeks in a pH7.0 phosphate buffer at 37... After 4 weeks of immersion, each tooth was biopsied with pH1.0 sodium acetate-hydrochloric acid buffer. The fluoride and calcium in the biopsy samples were analyzed by means of fluoride ion electrode and atomic absorption spectroscopy, respectively. The following results were obtained: (1) The fluoride in the enamel was significantly increased by the incorporation of fluoride from the F+sealant. Almost all fluoride in the surface enamel was found to be fluorapatite by the method of alkaline extraction. (2) The amount of fluoride increased by APF application was about 50% of that of F+sealant application. (3) The calcium released from the enamel treated with F+sealant or APF decreased by 13% and 9%, respectively, compared to that without treatment.
The purpose of this study was to investigate the relationship between the amount of fluoride in the enamel, taken from a fluoride-releasing sealant (F+sealant) and acid resistance. The F+sealant was applied to the bovine enamel from 1 week to 6 months. After the removal of the F+sealant, the bovine teeth were immersed in phosphate buffer from 1 month to 6 months. At each time period, the enamel was biopsied with acid and its fluoride and calcium concentration were analyzed. Results were as follows: (1) It was suitable to immerse the teeth in 1M KOH solution for 2 days in order to remove the loosely bound fluoride produced by the fluoride application from the enamel. (2) The amount of fluoride in the surface enamel increased in proportion to the application time of F+sealant. (3) The amount of calcium dissolved from the enamel showed the significant decrease by the F+sealant application, while no difference was shown by the application time. (4) The amount of fluoride in the surface enamel acquired by the F+se alant was maintained for 6 months after the removal of the F+sealant. (5) The amount of calcium dissolved from the enamel showed no difference in the period of immersion time.
This study was designed to investigate the effects of CO2 laser irradiation on the dentin microstructure, dentin adhesion of resin composites and dental pulp. An artificial caries lesion was produced on the bovine dentin, immersing in 0.4mol/l acetic acid. Three kinds of dentin (sound dentin, outer or inner caries dentin) surfaces were pretreated by the laser irradiation, acid etching or no-treatment. The tensile adhesion-test of these pretreated dentin surfaces was performed. The changes in these dentin surfaces by the various treatments including the laser irradiation and the resin-dentin interfaces were examined by the SEM. Furthermore, histopathological study using monkey teethwas conducted to examine the effect of the laser irradiation on the dental pulp. Histopathological changes in the pulp were found at 3 and 90 days after the operation. The findings were as follows: 1. The outer highly and inner partially decalcified layers produced in the bovine dentin were each approximately 200μm in thickness. 2. The bond strength of the resin composites to the laser pretreated sound dentin was approximately 40kgf/cm2. Those of the laser pretreated outer and inner decalcified dentins were about 60kgf/cm2. 3. At the initial stage, the laser irradiation (output power 3W: irradiation period 0.5 second) exibited a slight pulpal response, producingirritation dentin formation in the latter stage without any severe histopathological change.
The regulation of collagenase gene expression in the human osteosarcoma-derived osteoblastic cell lines MG-63, U2-OS and human fibloblast cell line IMR-90 was investigated by Northern blot analysis. Exposure of quiescent MG-63, U2-OS and IMR-90 cells to 12-0-tetradecanoyl-phorbol-13-acetate (TPA) and 10-0 fetal calf serum (FCS) resulted in the induction of mRNA encoding collagenase. Epidermal growth factor (EGF) induced collagenase mRNA in the IMR-90 cell but not in the MG-63 and U2-OS cells. In the IMR-90 and MG-63 cells, EGF stimulated the transcription of the c-fos and c-jun genes encoding the transcriptional factors which interact directly with the promoter region of the human collagenase gene. Parathyroid hormone and 1, 25-dihydroxyvitamin D3 did not increase the collagenase mRNA level in both osteosarcoma cells. Recombinant interleukin-1β (rIL-1β) induced collagenase and c-jun but no t c-fos mRNA in the MG-63 cell. The induction by rIL-1β was blocked by cycloheximide and dexamethasone. Transforming growth factorβ 1 blocked the FCS-induced collagenase gene expression but partially inhibited the rIL-1β-induced gene expression in the MG-63 cell. These results suggest that the collagenase activity is regulated not only by post-translational modification but also at the transcriptional level by the various factors in bone.
Inactivation of two tumor suppressor genes, RB and p53, is associated with tumor formation. To elucidate the molecular basis of the tumorigenesis of human osteosarcoma, structural and expressional alterations of these two genes were examined in five human osteosarcoma cell lines, two of which were from Japanese patients. In addition, I analyzed two adenovirus E1A. binding proteins, p107 and p300, putative “tumor suppressor gene products”, which share similar properties with the RB protein in binding to the E1A oncoprotein. Detailed analyses of the DNA, mRNA, and protein showed that (1) 3 lines including both Japanese lines lost the expression of the RB protein due to either the absence or the alteration of mRNA caused by DNA rearrangement, (2) abnormality of p53 gene was detected in all cell lines : 4 lines lost p53 expression due to either gene loss or the absence of mRNA, and one line expressed an abnormal form of the protein without detectable DNA and mRNA alterations and (3) no significant alteration of p107 or p300 was detected in all cell lines. These results further confirm that inactivating mutations of p53 and RB genes are deeply involved in the carcinogenesis of human osteosarcoma and suggest that p107 and p300 may not play a role in the tumorigenesis.