Biomedical subjects
P L Fan
Publications and source records attributed to P L Fan.
Irradiance of visible light-curing units and voltage variation effects.
The irradiance in the wavelength of 450 to 500 nm of nine visible light-curing units was measured at 120 V input voltage. The highest irradiance was more than 20 times that of the lowest. Irradiance was also measured at 90 to 130 V input. Irradiance and depth of cure at lower input voltages were also examined.
The use of mercury in dentistry: a critical review of the recent literature.
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Radiopacity of light-cured posterior composite resins.
Radiographic images of teeth and restorations were used to evaluate the radiopacity of 11 light-cured posterior composite resins. The radiopacity of these composite resins provided enough variation on radiographs so that clinicians distinguished the images of the restoration from adjacent tooth structure.
Ceramics: their place in dentistry.
A transfer molded ceramic coping material, Cerestore, and a castable ceramic, Dicor, are commercially available for fabrication of all-ceramic crowns. The manufacturers indicate their use should be in single unit anterior or posterior crowns. Tooth preparations are similar and should have rounded lines angles to avoid sharp points which may cause stress concentration. The amounts of tooth reduction are also similar and range from 1.0 to 2.0 mm depending on the location of surfaces. There are variations in fabricating procedures but both involve heat treatment and special equipment. Cerestore requires eventual veneer build-up and shading. Dicor requires surface shading. Both are evaluated and classified by the Council on Dental Materials, Instruments and Equipment of the American Dental Association. At least three other ceramic systems are being developed but are not yet commercially available.
Safety of amalgam.
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Assessment of noise-reducing devices for the dental office personnel.
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Evaluation of light transmission characteristics of protective eyeglasses for visible light-curing units.
Eyeglasses with protective filters are recommended for users of visible light-curing units to decrease the intensity of blue light reaching the eyes. The transmission curves of 20 commercially available filter glasses are obtained. The irradiance from eight curing units through these glasses is measured. The reduction in irradiance through the filter glasses is related to the transmission curves.
Polymerization of composites by sequential and continuous irradiation with visible light.
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Postirradiation comparison of photoactivated composite resins.
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Color comparisons of composite resins of various shade designations.
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A mathematical model for post-irradiation hardening of photoactivated composite resins.
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Alternative interpretations of water sorption values of composite resins.
Water sorption values for direct filling resins and an unfilled resin were much more similar at 30 days when expressed as mg/g organic matrix than as mg/cm2 or weight percent. This interpretation is indicative of the water sorption characteristics of resin matrices. The values are even more indicative when solubility or leaching is taken into consideration. With the specimen sizes used in this study, the effect of the kinetics of water sorption could be minimized by using values obtained after immersion in water for 30 days.
Effect of finishing on color and gloss of composites with different fillers.
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Effects of backing reflectance and mold size on polymerization of photo-activated composite resin.
The in vitro depth of cure of a visible-light-activated microfilled composite, as influenced by backing reflectance and mold size, was investigated using microhardness measurements. More extensive polymerization was obtained with higher values of backing reflectance. Mold size larger than the cross-sectional area of the photo-activating beam also increased the degree of polymerization. Backing reflectance and mold size are influential factors and need to be defined in depth-of-cure evaluations if in vitro measurements are to be valid predictors of clinical performance.
Evaluation of an alginate substitute using specification requirements.
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Resin dentin bonding systems. Council on Dental Materials, Instruments, and Equipment.
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Silver solders exposed to cleansers.
Substantiation of the adverse replies received by the Council regarding the increased corrosion of stainless steel-silver solder couples exposed to Efferdent's New Improved 36% stronger formulation is not made. Distinctions are, however, observed between the modes of corrosion occurring in the New Improved Efferdent and in the original Efferdent formulation. Corrosion in the New Improved Efferdent occurs via the formation of soluble zinc and copper chlorides that leave the selectively attacked microstructure visible, and in Efferdent nonprotective corrosion product deposition consisting of hydroxides and sulfides occurs that obscures the underlying substrate solder microstructure. The apparent increase in corrosion with New Improved Efferdent may be caused by the incorrect association between macroscopic surface appearance change and the amount of corrosion damage.