Improved health owes less to advances in medical science than to changes in the external environment, and to a favorable trend in the standard of living. We are healthier than our ancestors not because of what happens when we are ill but because we do not become ill; and we do not become ill not because of specific protective therapy but because we live in a healthier environment. In its preoccupation with the minutiae of diagnosis and the pathogenesis of disease, medicine is in danger of neglecting what has hitherto proved its most powerful resource-the manipulation of the external environment.
A cross-sectional exploratory survey was conducted in six West Malaysian schools involving 762 fifteen-to eighteen-year-old secondary school students. Periodontal health status was assessed using the Community Periodontal Index of Treatment Needs (CPITN), utilizing six index teeth to represent the six sextants of the mouth. The results indicated that 66.8% of the students examined had healthy gingiva (Score 0), 2.6% had bleeding of the gingiva on gentle probing, while 30.6% had calculus on their teeth. In terms of treatment needs, 35.0% of those examined needed oral hygiene education, 34.4%, on the other hand, required scaling. No student was found to require complex treatment. Sex-specific comparison revealed a slightly higher prevalence of calculus formation in male students. In terms of race, the Malays had a higher prevalence of calculus formation than either Chinese or Indians.
Co-Cr alloy is used more frequently than Ni-Cr alloy as a nonprecious alloy for cast plates in Japan. Titanium with good biocompatibility has often been contained in the composition of this Co-Cr alloy. However, since the melting temperature of Co-Cr alloy is very high, about 1300°C, and it oxidizes easily, a vacuum-pressure casting machine capable of melting this alloy in a reduced atmosphere has recently been developed. In this study, using the vacuum-pressure casting machine, the possible effects of sectional area and the number of sprues attached to the cast plate wax pattern, as well as the alloy components, on the castability of three kinds of Co-Cr alloy containing titanium were examined. It was found that all of these parameters had significant effects on Co-Cr alloy castability.
The relationship between complaints about temporomandibular joint (TMJ) sounds and the prevalence of disc displacements was studied. The rate of incidence of TMJ sounds was 42% in the 50 subjects investigated. In the subjects with TMJ sounds, 19% were diagnosed as having articular disc displacements. In the 58% sound-free subjects, 14% were found to have disc displacements. Therefore, it seems that patients with TMJ sounds do not always have disc displacements, and that a sound-free state does not necessarily indicate a healthy TMJ.
Aqueous solutions of methacryloyl tyrosine amide (MTYA), glyceryl methacrylate (GM), glutaraldehyde and succinic acid were prepared and their effectiveness as pretreatment reagents was evaluated by measuring the tensile bond strengths between resin composite and polished enamel. Pretreatment of polished enamel with MTYA·GM·S3 (A : 6% MTYA + 70% GM aqueous solution, B : 3% succinic acid aqueous solution) gave bond strengths of about 7 MPa, whereas pretreatment with MTYA·G·GM?S3 (A : 6% MTYA + 70% GM aqueous solution, B : 3% succinic acid + 2% glutaraldehyde aqueous solution) gave values of about 5 MPa. The mean bond strengths of each after 60s of scrubbing with MTYA.GM.S3 or by MTYA·G·GM·S3 were raised to about 9.5 MPa, and the type of bond failure was fracture of the bonding agent. Although there were no resin tags, it was found that resin composite was able to adhere to polished enamel without acid etching.
The maximum protuberance and the cervical line of 48 upper first molars and 56 second molars were observed using a three-dimensional measuring device. On the basis of the results, the relationship between the maximum protuberance and the cervical line was investigated on the respective contour line and lateral aspect waveform. The contour of the cervical line was positioned at the center of the maximum protuberance in both first and second molars. The distance of the lateral aspect between the measurement points of the maximum protuberance and the cervical line were wider in the mesiodistal direction than in the buccolingual direction. In the second molar, the distance between the maximum protuberance and the cervical line was narrower, and the stricture from the tooth crown to the cervical line on the second molar was decreased. The lateral aspect waveform of the cervical line and maximum protuberance tended to be similar, but the top-to-bottom distance of undulation on the maximum protuberance was longer than that of the cervical line. The buccolingual direction of the lateral aspect waveform showed much more marked fluctuations than that of the mesiodistal direction.
Several lines of recent evidence have suggested that transferrin plays a significant role in tissue interaction or morphogenesis at early stages of embryo development. In the present study, an anti-chicken transferrin antibody was produced and its basic characteristics were clarified as a basis for use in further studies. An antiserum termed Toraji 3 was raised against chicken transferrin and purified into IgG and ligand-affinity-purified fractions. These three preparations of the antibody gave an intense immunohistochemical signal in visceral yolk sac and developing liver, both of which are known to be major producers of transferrin in early development. In immunoblot analysis, these three preparations detected 70-kDa transferrin, whereas the ligand-affinity-purified preparation showed higher specificity. It was also demonstrated by enzymelinked immunosorbent assay and immunoblotting that Toraji 3 antibody bound preferentially to chicken transferrin and showed a negligible binding to human transferrin.