Comparison of effects of diode laser and CO2 laser on human teeth and their usefulness in topical fluoridation.

Various authors have reported more effective fluoridation from the use of lasers combined with topical fluoride than from conventional topical fluoridation. Besides the beneficial effect of lasers in reducing the acid solubility of an enamel surface, they can also increase the uptake of fluoride. The study objectives were to compare the action of CO(2) and GaAlAs diode lasers on dental enamel and their effects on pulp temperature and enamel fluoride uptake. Different groups of selected enamel surfaces were treated with amine fluoride and irradiated with CO(2) laser at an energy power of 1 or 2 W or with diode laser at 5 or 7 W for 15 s each and compared to enamel surfaces without treatment or topical fluoridated. Samples were examined by means of environmental scanning electron microscopy (ESEM). Surfaces of all enamel samples were then acid-etched, measuring the amount of fluoride deposited on the enamel by using a selective ion electrode. Other enamel surfaces selected under the same conditions were irradiated as described above, measuring the increase in pulp temperature with a thermocouple wire. Fluorination with CO(2) laser at 1 W and diode laser at 7 W produced a significantly greater fluoride uptake on enamel (89 ± 18 mg/l) and (77 ± 17 mg/l) versus topical fluoridation alone (58 ± 7 mg/l) and no treatment (20 ± 1 mg/l). Diode laser at 5 W produced a lesser alteration of the enamel surface compared to CO(2) laser at 1 W, but greater pulp safety was provided by CO(2) laser (ΔT° 1.60° ± 0.5) than by diode laser (ΔT° 3.16° ± 0.6). Diode laser at 7 W and CO(2) laser at 2 W both caused alterations on enamel surfaces, but great pulp safety was again obtained with CO(2) (ΔT° 4.44° ± 0.60) than with diode (ΔT° 5.25° ± 0.55). Our study demonstrates that CO(2) and diode laser irradiation of the enamel surface can both increase fluoride uptake; however, laser energy parameters must be carefully controlled in order to limit increases in pulpal temperature and alterations to the enamel surface.

Comparison of the likelihood ratios of two binary diagnostic tests in paired designs.

The performance of two binary diagnostic tests is traditionally compared by their respective sensitivities and specificities. Other measures to describe the performance of a binary diagnostic test are likelihood ratios, defined as the ratio between the likelihood of a diagnostic test result in a group of diseased patients and the likelihood of a diagnostic test result in a group of non-diseased patients. In this study, we propose a method, based on the log-transformation of the ratio of the likelihood ratios, to compare the likelihood ratios of two binary diagnostic tests in paired designs. We have deduced hypothesis tests to compare the likelihood ratios and we have carried out simulation experiments to study the power and the type I error of the hypothesis tests deduced. We have also deduced a joint hypothesis test to simultaneously compare the likelihood ratios. The procedure used has been extended to the situation in which more than two binary diagnostic tests are applied to the same sample, and the situation in which two diagnostic tests with multilevel results are compared.

In vitro activity of beta-lactam and non-beta-lactam antibiotics in extended-spectrum beta-lactamase-producing clinical isolates of Escherichia coli.

The activity of different beta-lactam and non-beta-lactam antibiotics was assessed against extended-spectrum beta-lactamase (ESBL)-producing and non-ESBL-producing clinical isolates of Escherichia coli. A phenotypic study to discover the presence of ESBLs in 399 clinical isolates of E. coli was made by the disk diffusion method following the Clinical and Laboratory Standards Institute (formely NCCLS, 2004) guidelines. The activity of different antibiotics was subsequently studied using the automated VITEK 2 system (bioMérieux, Marcy l'Etoile, France). One hundred fifteen isolates proved to be ESBL-producing and 284 non-ESBL-producing. Among the former, percentage susceptibilities to the antibiotics assayed were meropenem and amikacin, 100%; piperacillin/tazobactam, 97.4%; cefepime, 94.8%; amoxicillin/clavulanic acid, 84.3%; tobramycin, 84.3%; gentamicin, 83.5%; cefoxitin, 83.5%; nitrofurantoin, 71.3%; cotrimoxazole, 46.1%; norfloxacin, 29.6%; ciprofloxacin, 27%; and ofloxacin, 26.1%.