PubMed · 5283147
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
M J Manhart. 1971. Simple bicuspid endodontics.. https://pubmed.ncbi.nlm.nih.gov/5283147/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
This study compared the correlation between the buccolingual inclination and the wear score of the mandibular teeth in Jomon (one of the ancestors of modern Japanese who lived from 5000 to 300 BC) and modern Japanese. Data were obtained from 40 modern male Japanese and 39 male Jomon skulls housed in the University Museum of the University of Tokyo and National Science Museum, Tokyo. For each specimen, three computed tomograms of coronal sections of the mandibular body were available. The second premolar, first molar and second molar of Jomon stood more vertically than those of modern Japanese. There were significant correlations between tooth wear and the buccolingual inclination of mandibular molars. When ancient and modern populations were compared, tooth wear was significantly greater and buccolingual tooth inclination was more vertical in the ancient people, who probably applied stronger masticatory forces than modern people. The results suggest that the mandibular molar orientation is more buccal and there is greater tooth wear in the first and second molars of people with strong masticatory function.
Tooth enamel has been shown to be an excellent dosimeter material for retrospective dosimetry. A complication is that it is sensitive to ultraviolet light (UV), creating a signal that interferes with the dosimetric signal. Irradiation of tooth enamel by UV-light induces a mixture of stable and unstable free radicals. The unstable radicals disappear in about three weeks. Stable radicals are created both at the dosimetric peak and at the same g-value as the native peak. The stable peak coinciding with the native peak shows saturation behavior both for UVA/B- and UVC-light. The signal intensity from the sun is roughly estimated to induce a signal comparable to 15 mGy/h from 60 kV X-rays. The blue lamps used by dentists when hardening plastic repairs contain a narrow tail in the UVA/B-region, and it is shown here that these lamps also contribute to the stable peak coincident with the native peak. The contribution to the dosimetry peak, though negligible, at least for the irradiation times is used in this work. Most of the problems with UVA/B-induced signal contributions can probably be avoided by not using front teeth and teeth close to plastic repairs.
BACKGROUND: In a 24-month clinical trial, the authors compared three brands of light-cured composite resins that were used to restore the posterior teeth of 38 patients. METHODS: A total of 88 Class I and 32 Class II restorations were made using Z100 (3M Dental Products Div.), Clearfil Ray-Posterior (Kuraray Co. Ltd.) and Prisma TPH (Caulk/Dentsply). Quadrant impressions were taken using a polyvinyl siloxane impression material, and stone casts were obtained every six months for indirect evaluations of anatomical form and marginal adaptation. The restorations were evaluated directly by three clinicians using the Ryge criteria. RESULTS: The authors statistically evaluated parameters at each recall period, using a chi 2 test; compared baseline scores with the recall scores, using a McNemar test; and evaluated changes in the parameters, using the Cochran Q test. Color match, cavosurface margin discoloration and secondary caries remained unchanged at the end of the 24-month recall period for all materials (P > or = .05). A total of 11.5 percent of the Z100 restorations and 16.7 percent of the Prisma TPH restorations showed a slight crevice along the margin (P < or = .05). The surface texture was scored as Bravo only for Clearfil Ray-Posterior restorations at the end of the study (P < or = .05). The authors found that the indirect evaluation results were different from the direct evaluations for Z100 and Prisma TPH. CONCLUSIONS: According to these findings, all the materials used are suitable for posterior restorations. The difference between the two evaluation methods can be attributed to the level of sensitivity. CLINICAL IMPLICATIONS: With the improvement in materials, careful case selection and application of the restorative techniques, posterior composites placed under appropriate conditions and monitored routinely can be expected to last 10 years or longer.