Noncariogenic Sweeteners: Sugar Substitutes for Caries Control

The evidence is clear that the incidence of dental caries is related to the frequency of eating sugar. The use of sugar substitutes is a suggested way of reducing sugar intake. A variety of noncariogenic sweeteners exists, but most have no practical value for caries control because of their technical or safety problems, taste, or cost. Urinary bladder tumorigenic effects have been reported in experimental animals treated with saccharin and cyclamates. Because of concerns for human safety, cyclamates were banned in the U.S., and saccharin use was permitted only by special legislation. The polyalcohols sorbitol and xylitol are important sugar substitutes since they are not efficient substrates for plaque bacteria and therefore produce only minimal plaque pH drop. Aspartame, with its sugar-like taste, is an excellent low-calorie sweetener now used in over 100 products under the name NutraSweet. Consumption of aspartame by normal humans is safe and does not promote tooth decay. Individuals with a need to control their phenylalanine intake should handle aspartame like any other source of phenylalanine

Characteristics of sealed-off waveguide CO_2 lasers

Gain and output power of sealed-off waveguide CO_2 lasers are presented as a function of gas mixtures and total gas pressure. Experimental data on circular-bore and square-channel waveguide lasers are presented. Output power per unit length of 0.2 W/cm is achieved for both types of lasers in agreement with gas-discharge scaling laws which are presented. Saturation intensities as high as 24 kW/cm^2 are inferred from the data. The effects of the optical properties of the waveguide wall material on the waveguide losses are discussed and theoretical waveguide loss versus wavelength is presented for BeO, Al_2O_3, and fused silica