HEALTH MEDIA WATCH GLASS IONOMER CEMENTS BOTH RELEASE AND TAKE UP FLUORIDE Glass ionomer cements can release fluoride, as well as take up significan...

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Glass ionomer cements can

release fluoride, as well as take up significant amounts of fluoride from external fluoride sources, according to a report in the September issue of Journal of Dentistry, which is an international journal published in England. British researchers conducted a study to test the ability of four glass ionomer cements to act as fluoride reservoirs, taking fluoride up from an external source—such as toothpaste or mouthwash—and then releasing it over time. Researchers suspended samples of four new glass ionomer cements in deionized water in individual sealable plastic containers and stored them at 37 C for the duration of the experiment. They then divided the samples into two test groups, each composed of five specimens of each cement. At day 28, researchers exposed one group to a toothpaste containing 0.32 percent sodium fluoride. They exposed these samples to the fluoride toothpaste again at day 58. Researchers exposed the second group of samples to the fluoride toothpaste only at day 58. Before and after each exposure, researchers monitored the release of fluoride from the cement into the deionized storage water before and after exposure, using a differential electrode cell. They found that all four cements released more fluoride on

the day after exposure to the fluoride toothpaste than they did the day before the exposure. They also discovered that fluoride-release rates returned to baseline within three days after exposure in all cases. In addition, they found that all of the cements in the first test group showed enhanced uptake and release of fluoride when they were re-exposed to the fluoride toothpaste at day 58. (J Dent 1998;26:591-7) DISINFECTANT DOES NOT AFFECT MICROLEAKAGE PREVENTION

Alcohol-based cavity disinfectants used as a cavity wash before the use of one-step dentin bonding systems do not affect the bonding agents’ ability to prevent microleakage, says a report in the Summer issue of The Journal of Clinical Pediatric Dentistry. Turkish researchers selected 80 children between the ages of 10 and 12 years who had a Class V cavity in a primary second molar that was about to exfoliate. Cavity preparations were treated with a bonding system alone; with combinations of either an alcohol-based disinfectant or a 2 percent chlorhexidine-based disinfectant with the bonding system; or with either of the disinfectants alone. The cavities then were restored with composite resin. The researchers extracted and stained all the test teeth one month later. They then sectioned the teeth to evaluate the stain depth. The researches found that when the alcohol-based disinfectant was applied as a cavity wash before the bonding system was used, it did not affect the

ability of dentin bonding agents to prevent microleakage. The 2 percent chlorhexidinebased disinfectant, however, had an adverse effect. Significantly higher levels of microleakage occurred when the disinfectant was used with the bonding system. (J Clin Pediatr Dent 1998;22[4]:299-305) SENSORY OVERLOAD

Two recently published studies investigated the effects created by certain odors and noise levels in the dental practice. dThe odor of eugenol evokes different emotional responses among patients, depending on the unpleasantness of their dental experiences, say researchers in an article in the August issue of The Journal of Dental Research. French researchers evaluated the emotional impact of the odors of three dental products— eugenol (found in cements that often are used in restorative procedures on vital teeth), menthol and methylmethacrylate— on volunteer subjects. To assess each odor’s impact, researchers used autonomic nervous system analysis and an 11-point scale that rated the pleasantness or unpleasantness of each odor. When researchers divided the subjects into two groups according to their own dental experiences—fearful or nonfearful— they found that subjects in both groups rated menthol as pleasant and methylmethacrylate as very unpleasant. In the case of eugenol, however, they found that it was considered pleasant by the subjects in the nonfearful group and unpleasant by subjects in the fearful group. Continued on page 1394

JADA, Vol. 129, September 1998 Copyright ©1998-2001 American Dental Association. All rights reserved.