RESUMEN
UNLABELLED: The aim of this in vitro study was to develop a replica technique aimed at reproducing an enamel surface exposed to erosive challenge. The replica technique was then used to compare the effect of treating enamel with different fluoride (F) solutions using an in vitro erosion model. Human molar teeth were split in two (total n=34 specimens), and half of each specimen was isolated with impression material. Part I: 10 specimens were exposed to either 0.18% or 1.8% citric acid, the impression material was removed and replicas were prepared. All specimens and replica models were analysed by profilometry and SEM. Part II: 24 specimens were treated with native 0.1 mol/L F-solutions (HF, SnF2, NaF and TiF4), the impression material was removed, and the specimens were then exposed to 1.8% citric acid. Replicas were prepared and analysed by profilometry and SEM. The median height difference between the F-treated areas and the non-treated areas for each F-solution was measured. SEM micrographs were analysed qualitatively blind bytwo of the authors. RESULTS: Part I--Replicas showed good topographical reproduction of the tooth specimens. Part II--HF had a significantly greater erosion-inhibiting effect than the other fluoride solutions at 0.1 mol/L F as shown by profilometry. SEM revealed a clearly defined border between F-treated and non-treated surfaces only for specimens treated with HF- and TiF solutions. In conclusion, the present replica technique was able to differentiate between the effect of treating enamel with different fluorides against dental erosion in vitro. The technique should be tested further for possible use in situ and in vivo.