Effect of citric acid erosion on enamel and dentin and possible protection by a novel bioactive borate adhesive system

Evaluation of Bioactive Glass and Low Viscosity Resin as Orthodontic Enamel Sealer: An In Vitro Study

The study aimed to evaluate the effect of applying fluoride bioactive glass (FBAG) and Alpha-Glaze® (resin sealer) on the shear bond strength of orthodontic brackets to enamel bonded by Transbond XT, brushing−abrasion durability, and their protective effect against simulated cariogenic acidic attack. Materials include 135 extracted premolars that were divided into three groups—FBAG, Alpha-Glaze, and control. The shear bond strength test was measured using an Instron Universal Testing Machine. The brushing abrasion challenge took place with a tooth-brushing simulator. Transmitted light microscopy examinations were performed after the specimens were demineralized for 4 days. The results show that the shear bond strength values of the three groups did not report any statistically significant differences: FBAG (28.1 ± 5.5 Mpa), Alpha-Glaze (32.5 ± 7.4 Mpa), and control (30.7 ± 6.5 Mpa) p < 0.05. The Adhesive Remenant Index (ARI) study showed chipping of enamel in 6.6% of Alpha-Glaze and control specimens and 40% of specimens had their enamel surface covered with resin. Furthermore, 30% of the FBAG and 100% of the Alpha-Glaze sealer specimens resisted the abrasion test. In conclusion, FBAG can serve as an orthodontic-sealer capable of protecting the enamel surface surrounding orthodontic brackets. However, the Alpha-Glaze sealer did not offer the capability of protecting the enamel.

Improved Enamel Acid Resistance Using Biocompatible Nano-Hydroxyapatite Coating Method

In this study, we attempted to develop a dental caries prevention method using a bioapatite (BioHap), an eggshell-derived apatite with nanoparticle size and biocompatibility, with a high-concentration fluoride tooth surface application method. The enamel acid resistance after the application of the proposed method was compared with that of a conventional topical application of fluoride using bovine tooth enamel as an example. The tooth samples were divided into three groups based on the preventive treatment applied, and an acid challenge was performed. The samples were evaluated for acid resistance using qualitative and quantitative analytical methods. The BioHap group demonstrated reduced enamel loss and improved micro-Vickers hardness, along with a thick coating layer, decreased reaction area depth, and decreased mineral loss value and lesion depth. The combination of BioHap with high-concentration fluoride led to the formation of a thick coating layer on the enamel surface and better suppression of demineralization than the conventional method, both qualitatively and quantitatively. The proposed biocompatible nano-hydroxyapatite coating method is expected to become a new standard for providing professional care to prevent dental caries.