There were two purposes of this study. The first purpose was to introduce the “X-ray TV M-mode waveform” which is reconstructed from sequential X-ray TV images and the “reconstructed ultrasound M-mode waveform” which is delivered from ultrasound B-mode images. The second purpose was to evaluate the usefulness of these two types of waveforms in the investigation of tongue movement during swallowing. The instrument system employed in this study consisted of ultrasound and X-ray TV synchronized by a time marker. After the X-ray images and ultrasound B-mode images were recorded on an optical disk, X-ray TV M-mode waveform and ultrasound M-mode waveform were reconstructed using an MC 68030/OS-9 computer. No significant differences in quality of images were observed between the X-ray TV M-mode waveform and the reconstructed ultrasound M-mode waveform. Therefore, both waveforms of the X-ray TV M-mode and the reconstructed ultrasound M-mode are equally useful in measuring tongue movement. (J. Oral Sci. 41, 1-4, 1999)

View full abstract

This study was undertaken to develop a three-dimensional reconstruction system using magnetic resonance (MR) images in order to visualize three-dimensional images of the temporomandibular joint (TMJ) including the disk. The computerized reconstruction program (written using Visual Basic for Windows, Microsoft Corp.) could reliably generate three-dimensional images of the TMJ. Image processing techniques made the tracing of images unnecessary, reduced complex human manipulation and associated measurement errors. This system, capable of treating fifty thousand pixels or more, generates smooth three-dimensional images of the TMJ. (J. Oral Sci. 41, 5-8, 1999)

View full abstract

The polymerization and copolymerization activity of dental monomers was investigated using the dynamic differential scanning calorimetry (DSC) method. As aliphatic dimethacrylate monomers, ethyleneglycol dimethacrylates with different lengths of ethyleneglycol and urethane dimethacrylates were used. As aromatic dimethacrylates, Bis-GMA (2, 2-bis [4- (3-methacryloxy-2-hydroxypropoxy) pheny1] propane), BMPEPP (2, 2-bis (4-methacryloxy poly-ethoxyphenyl) propane), and DMB (1, 2-dimethacryloyloxy benzene) were used. Ethyleneglycol dimethacrylates showed sharp exothermic peaks, and the maximum temperatures (Tp) at the exothermic peaks of the DSC curves decreased according to the lengths of ethyleneglycols. Among urethane dimethacrylates, UDMA (dimethacryloxyethyl 2, 2, 4-trimethylhexamethylene diurethane) and DMPHU (di- (2-methacryloxypropyl) hexamethylene diurethane) showed sharp exothermic peaks, but DMEHU (di- (2-methacryloxyethyl) hexamethylene diurethane) showed an endothermic peak as well as exothermic peaks. This suggests that reactions other than polymerization occurred in the case of DMEHU. The polymerization activity of aromatic dimethacrylates was lower than that of ethyleneglycol dimethacrylates and urethane dimethacrylates. The copolymerization activity of TEGDMA (triethyleneglycol dimethacrylate) and DMB was also investigated using the dynamic DSC method. The DSC curves of the copolymerization between DMB and UDMA or BMPEPP showed broad peaks, but the DSC curves of the copolymerization between TEGDMA and UDMA or BMPEPP showed sharp peaks. The copolymerization activity of TEGDMA was better than that of DMB. (J. Oral Sci. 41, 9-13, 1999)

View full abstract

In dentistry, acrylates have been used for preparing denture bases for 50 years. Although polymethylmethacrylates (PMMA) are known to be an ideal base material, they possess some undesirable mechanical properties, especially their impact strength and tensile strength, which appear to be unsatisfactory for some applications. Additives and fibers have therefore been used to enhance and improve these properties over the last two decades. The present article describes the mechanical properties, impact and tensile strength of PMMA reinforced with chopped ultra-high molecular weight polyethylene fiber (6 mm long). It was found that, although the processing involved for high loading of fibers into the PMMA was difficult, the resulting improvement of impact strength was substantial. (J. Oral Sci. 41, 15-18, 1999)

View full abstract

Today, Japan as a society is aging. The average life expectancy of Japanese people is approximately 80 years. One result of this is that preservation of masticatory functions in elderly people has become increasingly important from the viewpoint of quality of life. In the furture, the use of dentures in facilitating masticatory functions as a substitute for teeth that are lost during the aging process will assume greater significance. Accordingly, appropriate evaluation and judgment of complete dentures for edentate jaws is crucial. This study was designed to elucidate the effects of the craniofacial form in complete denture wearers on the mode of activity of gnathic functions. First, subjects wearing complete dentures in both the upper and lower jaws were instructed to carry out vertical clenching, and bite force direction was determined. These data were then related to the subject's craniofacial morphology. These results suggest that the bite force direction in complete denture wearers is not affected by gender differences, but is closely associated with lateral craniofacial morphology, and that appropriate setting of occlusal plane and the occluded vertical dimension is extremely important in the preparation of complete dentures. (J. Oral Sci. 41, 19-27, 1999)

View full abstract

Experimental studies have demonstrated a structural and functional correlation between the pancreas and salivary glands. Therefore, one may suppose that caerulein plus secretin, used in functional exploration of the exocrine pancreas, could exert an influence on acid phosphatase activity (AcP) and its isoenzymes (tartrate sensitive-TsAcP, tartrate resistant-TRAP acid phosphatases) in whole saliva in humans. The current study was conducted in 14 asymptomatic volunteers (six woman and eight men, mean age 34, range 27-45). Salivary secretions were collected under basal conditions (intravenous infusion of 0.15 mol l^-1 NaCl) and during intravenous infusion of secretin plus caerulein at different doses. Stimulation with secretin (50 mKE kg^-1 min^-1) and caerulein (2.5 ng kg^-1 min^-1) resulted in a marked and rapid decrease of salivary flow rate. TRAP activity decreased during the first 20 min of hormonal infusion (1.09 ± 0.19 mU ml^-1 vs.1.93 ± 0.18 mU m^-1, 1.16 ± 0.12 mU m1^-1 vs.1.86±0.17mU mr^-1, p<0.05). AcP and TsAcP activity during intravenous infusion of secretin plus caerulein remained unchanged. These results point to a wider than expected participation of the digestive system in hormonal control of biochemical processes taking place inside the oral cavity. (J. Oral Sci. 41, 29-34, 1999)

View full abstract

The aim of this cross-sectional study was to determine, using PocketWatch^TM, the relationship between the level of aspartate aminotransferase (AST) in gingival crevicular fluid (GCF) and conventional measures of periodontal status, such as probing depth, attachment level, bleeding on probing and gingival index, in patients with untreated chronic periodontitis. A total of 15 patients with chronic periodontitis were enrolled. Their periodontal status and AST levels in their GCF were measured (n=93) and statistically analyzed. There was a statistically significant difference in AST levels between diseased periodontal sites and healthy sites (p<0.0001). The coefficients of correlation between AST levels and probing depth, attachment level and gingival index at all sites were 0.436, 0.266 and 0.468 (Spearman rank correlation). The correlation coefficients were too small to show a definite relationship between AST levels and individual measures of clinical periodontal status. However, AST levels may help to confirm clinical observations in patients with chronic periodontitis before therapy, since AST levels differentiate active and inactive periodontal diseased sites. (J. Oral Sci. 41, 35-40, 1999).

View full abstract

The use of fine needle aspiration biopsy (FNAB) in the diagnosis of many lesions in different parts of the body is quite widespread, while it has been used for oral lesions only very recently. This technique has many advantages including ease of use, cost effectiveness, convenience and accuracy. The present study, investigated the diagnostic value of FNAB in solid oral lesions using, specimens from 90 patients (56 females, 34 males), with ages ranging from 7-70 years which were examined in comparison with their histopathological sections. Cytological specimens were evaluated based on the presence of diagnostic cells. Ninety cases were divided into two major groups those with fibrous and nonfibrous lesions, for the the purposes of histopathological diagnosis. Among all fibrous lesions, cytological diagnosis was possible in 20 cases, whereas 45 out of 49 non-fibrous oral lesions yielded diagnostic cells. In conclusion it was shown that FNAB was not very diagnostic in fibrous lesions. However, in lesions with loose stroma, rich in vessels or inflammatory cells, and in malignant tumors, FNAB was a very successful method which yielded a correct diagnosis. (J. Oral Sci. 41, 41-45, 1999)

View full abstract