RESUMEN
The aim of this study was to test the possibility of the concomitant formation of calculus deposits and caries from in situ dentin caries model for short time periods. Six volunteers wore palatal removal appliances with four polished dentin specimens protected from intra-oral mechanical forces for up to 14 days. Each volunteer applied a 50% sucrose solution (four times a day) on the specimens and performed a daily mouthwash with 0.05% NaF. Samples were removed after 2, 5, 9 and 14 days in situ. Demineralization was analyzed by stereomicroscopy and SEM (secondary electrons and backscattered electrons modes) and calculus was analyzed by energy dispersive spectroscopy and fluorescence spectroscopy. Seventeen samples, at least one sample from each volunteer, presented dental calculus on both carious and non-carious ones, detected in all time intervals. Ca/P ratios of dental calculus ranged from 1.1 to 1.7. Some large calculus deposits on carious surfaces were confirmed by fluorescence. In conclusion, concomitant caries and calculus formation can be found in dentin caries formed in situ. This has important repercussions on the study of surface phenomena on the interface between hard dental tissues and dental plaque.
RESUMEN
We report on the combined action of a cw diode laser and a train of ultrashort pulses when each of them drives one step of the 5S-5P-5D two-photon transition in rubidium vapor. The fluorescence from the 6P(3/2) state is detected for a fixed repetition rate of the femtosecond laser while the cw-laser frequency is scanned over the rubidium D(2) lines. This scheme allows for a velocity selective spectroscopy in a large spectral range including the 5D(3/2) and 5D(5/2) states. The results are well described in a simplified frequency domain picture, considering the interaction of each velocity group with the cw laser and a single mode of the frequency comb.