Comparative evaluation of the surface effect of two toothpastes with different fluorine concentration on primary teeth surface

BACKGROUND: The purpose of this study is to analyze the effect of two toothpaste, with different fluorine concentrations, on the enamel surface of deciduous teeth. The study was performed in vitro by means of SEM microscopy. METHODS: A selection of 20 deciduous molars was prepared. The teeth were extracted as a result of orthodontic treatments or physiological replacements. The procedures were performed at the UOC of Pediatric dentistry Sapienza University of Rome department of Oral and Maxillo-Facial Science. Each element, with no sign of cracks on the enamel, was preserved in normal saline and then sectioned at a cementum-enamel junction level. Successively the external and occlusal surfaces have been etched with 37% orthophosphoric acid for 1 minute in order to reproduce the demineralization that occurs in the oral environment. Each fragment of the same tooth was treated with two different toothpastes (with 500ppm and 1400ppm fluorine concentration respectively) for 15 days and manually brushed three times a day using pediatric toothbrushes for 2 min. Each section was rinsed and preserved in normal saline, renewed every brushing session. Finally a roughness analysis was carried out. RESULTS: In the samples treated with 500 ppm both surfaces present a cribrosus layer, uneven, with a worn out appearance and visible crater-like spaces. In the samples treated with toothpaste at 1400 ppm of fluorine, an improvement of the surface morphology of the enamel has been highlighted, which however maintains a superficial roughness not completely attenuated, due to a non-homogeneous distribution of the same material. The roughness analysis values highlight these differences between the two materials. CONCLUSIONS: The use of toothpaste with a high concentration of fluorine, compared to those with low concentration, shows a greater remineralizing power on surfaces of artificially demineralized deciduous teeth, ensuring a character of caries prevention. Toothpastes with 500 ppm, despite reducing the potential risk of systemic accumulation of fluorine (due to accidental ingestion of the material during daily oral hygiene), do not demonstrate significant effectiveness in the repair and protection of the enamel surface by acidic substances attack. These findings therefore translates into an increased risk of the onset of caries.