Characterization of a Toothpaste Containing Bioactive Hydroxyapatites and In Vitro Evaluation of Its Efficacy to Remineralize Enamel and to Occlude Dentinal Tubules

Abstract

Demineralization of dental hard tissues is a well-known health issue and the primary mechanism responsible for caries and dentinal hypersensitivity. Remineralizing toothpastes are nowadays available to improve conventional oral care formulations regarding the prevention and repair of demineralization. In this paper, we analyzed the chemical-physical features of a commercial toothpaste (Biosmalto Caries Abrasion and Erosion, Curasept S.p.A., Saronno, Italy), with particular attention paid to the water-insoluble fraction which contains the remineralizing bioactive ingredients. Moreover, the efficacy of the toothpaste to induce enamel remineralization and to occlude dentinal tubules has been qualitatively and semiquantitatively tested in vitro on human dental tissues using scanning electron microscopy and X-ray microanalysis. Our results demonstrated that the water-insoluble fraction contained silica as well as chitosan and poorly crystalline biomimetic hydroxyapatite doped with carbonate, magnesium, strontium, and fluoride ions. The formulation showed excellent ability to restore demineralized enamel into its native structure by epitaxial deposition of a new crystalline phase in continuity with the native one. It was also able to occlude the dentinal tubules exposed completely by acid-etching. Overall, this study demonstrated that the tested toothpaste contained a biomimetic ionic-substituted hydroxyapatite-based active principle and that, within the in vitro conditions analyzed in this study, it was effective in dental hard tissue remineralization.

Enamel Remineralization and Dentine Tubules Occlusion by Bioactive Formulations Based on Ion-Doped Nanohydroxyapatite and Precursor Nanoparticles.

“…Then, an aliquot was dissolved in a 6 wt% HNO 3 solution to collect the acidinsoluble fraction. The latter fraction was collected by centrifugation (10,000 rpm for 5 min), freeze-dried overnight, and then weighted [17].…”

“…Then, on both dentine and enamel sections,two perpendicular 0.5 mm-deep notches were made on the top surface of each specimen to mark four areas using a low-speed diamond disc (Horico, Berlin, Germany, Figure 7B). All surfaces were polished using silicon carbide paper (600 and 1200 grit), and the surfaces were etched with a 37 wt% H 3 PO 4 solution for 30 s, followed by extensive rinsing with water [17].…”

The use of hydroxyapatite toothpaste to prevent dental caries

“…Following acidic insults, demineralized enamel appears porous with irregularities or divots present at the surface [6] . Brushing extracted teeth with HAP-containing toothpaste has been found to result in HAP crystals binding and restoring the tooth surface and essentially filling in the pitted areas, as visualized by SEM [6,[20][21][22][23] and light microscopy [24], while the use of fluoride containing toothpaste (1040 ppm F − ), however, produced very little surface remineralization and failed to repair any of the enamel surface irregularities. Semi quantitative analysis of mineral content showing that samples treated HAP-containing toothpaste had significantly higher levels of calcium content compared to controls [25].…”

“…In deeper lesions such as those extending into dentin, it is unknown whether HAP particles can diffuse to deeper lesion surfaces. which bind to enamel surfaces to fill in demineralized surface defects and micropores [14] Improvement of the natural tooth surface remineralization process [65] Remineralization of enamel/dentin Reports of increased surface remineralization by SEM and light microscopy, surface hardness, and mineralization as measured by TMR of HAP toothpaste compared to fluoride toothpaste in vitro and in situ [66] Similar results were found in terms of surface hardness between HAP toothpaste and 1450 ppm fluoride toothpaste [3] The effects on dentin remineralization In situ studies demonstrate equivalency of HAP toothpaste to 500 ppm fluoride toothpaste as measured by TMR Fluoride toothpaste can lead to a limited increase in remineralization at the outer tooth surface [19,67] Caries Prevention Non-inferiority of 10% microcrystalline HAP toothpastes compared with fluoride toothpastes in caries progression as measured by ICDAS score progression in both primary and permanent dentition [4,5] The caries prevention of fluorides is well-established [68] Source of calcium and phosphate Does not rely on calcium and phosphate in saliva [6] Relies on salivary flow for calcium and phosphate ions [67] Adverse effects No adverse health events have been reported [63] Dental fluorosis, systemic toxicity leading to bone fracture [69], developmental neurotoxicity [70,71] and gastric irritation when used in excess [72] Whitening HAP gel found to produce increased brightening effects in vitro and in vivo [53,58,59] No significant difference in tooth shade score from baseline [73] Sensitivity Decreased dentinal hypersensitivity compared to fluoridated toothpaste and tubule occlusion [20,56,57] No significant difference between fluoride toothpaste and placebo [62] Tschoppe et al [3] compared the remineralizing effects of different HAP toothpaste formulations using bovine incisors dentin and enamel lesions. Samples were brushed twice daily for five seconds for a total of two weeks using either the HAP or fluoride toothpaste and then analyzed using transverse microradiography (TMR).…”

Carbon Nanotubes (CNTs)-Reinforced Magnesium-Based Matrix Composites: A Comprehensive Review

“…The advantageous properties could be attained only if the reinforcements are distributed homogeneously and not clustered in the matrix. According to the literature available [ 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 , 171 , 172 , 173 , 174 , 175 , 176 , 177 , 178 , 179 , 180 , 181 , 182 , 183 , 184 , 185 , 186 , 187 ], limited research has been performed on CNT-reinforced MMCs due to difficulties in fabricating and dispersion of CNTs in the matrix. Most studies investigated the fabrication methods such as the casting process and powder metallurgy for developing Mg-based alloy [ 188 , 189 , 190 , 191 , 192 , 193 , 194 , 195 , 196 , 197 , 198 , 199 , 200 , 201 ,…”