PubMed · 9540550
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W G Dickerson. 1994. Restoring endodontically treated teeth.. https://pubmed.ncbi.nlm.nih.gov/9540550/
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OBJECTIVES: The light intensity of curing lights used in private dental offices was measured using commercial curing and heat radiometers and related to uniformity of cure depth of standardized composite specimens. METHODS: The intensity of 130 curing light from 107 dental offices was measured with curing and heat radiometers. Due to analogue readings, results were recorded in steps of 25 mW cm-2 and assigned a category number. A total of 50 lights were randomly selected to polymerize standardized 3 mm thick composite cylinders. The composite was irradiated for 50 s according to the manufacturer's instructions. The Knoop hardness value was measured at the top and bottom surfaces and the uniformity of cure depth was calculated from the ratio of these two values. RESULTS: Light intensity measured by the curing and heat radiometers was in the range of 25-825 and 0-325 mW cm-2, respectively. Functions of maximum likelihood estimation of the top and bottom surface hardness were 57 N/N + 1.3 and 80 N/N + 17.7, respectively (N = light intensity category number). The relationship between the logarithmic transformation of the hardness ratio and light intensity was linear (R2 = 0.84 p < 0.001). CONCLUSION: According to the manufacturer, a curing light is considered as unsuitable for use with a reading of < 200 mW cm-2 by the curing radiometer and > 50 mW cm-2 by the heat radiometer. Applying these criteria to the present study, 46% of the lights (without repetitions) required repair or replacement. The strong correlation found between the hardness ratio and light intensity verifies the usefulness of the curing radiometer in predicting the polymerization ability of the light activation units.
OBJECTIVE: The purpose of this study was to determine whether the dental pulp and lesions of pulpal origin (eg, pulp polyps, periapical granulomas, and periapical cysts) exhibit receptors for the sex steroid hormones estrogen, progesterone, and androgen. STUDY DESIGN: Staining for the receptors of the hormones estrogen, progesterone, and androgen was accomplished through use of available immunohistochemical detection techniques. Pulpal tissues were obtained from freshly extracted human third molars; the other tissues were obtained from the Oral and Maxillofacial Pathology Laboratory archives. Ten samples of each tissue were processed and immunostained for these specific receptors. RESULTS: Staining for estrogen and androgen receptors was essentially negative for all cell populations examined. However, positive progesterone receptor staining of varying degrees was noted in 8 of 10 pulpal specimens. Primarily, pulpal fibroblasts and odontoblasts exhibited positive immunoreactivity. CONCLUSIONS: The results of this study suggest that although the dental pulp may be a potential target tissue for progesterone, evidence is lacking with respect to the other sex steroid hormones.
Two commercial visible-light (VL)-cured composite resins were examined for their optical properties by diffuse reflectance measurements in VL spectrum and Kubelka-Munk's theory. Cured Silux Plus displayed diffuse reflectance similar to that of cured Z100, although uncured Silux Plus showed diffuse reflectance less than that of uncured Z100. By Kubelka-Munk's analyses, two optical constants of the composites at eight wavelengths such as absorption and scattering coefficients were calculated using the difference in diffuse reflectance of the composites backed between white and black standards. Upon curing, the two optical constants of the composites significantly altered especially in the shorter wavelengths. By lowering the wavelength, two optical constants of the composites tended to increase, giving rise to less light reflection and transmission. The theoretical optical transmittance of the composites was expressed in terms of hyperbolic functions of thickness of the composites at eight wavelengths in VL, dependent upon the two optical constants. The actual optical transmittance of 1 mm composites were fairly comparative with the theoretical values at 1 mm. The depth of cure of the two composites matched well with the thickness of the uncured composites which yielded the minimum theoretical optical transmittance in the wavelength region of 400-500 nm.