Restoring composite resins with the optimal shades for all primary teeth is a great challenge for pediatric dentists. A newly developed single-shade composite resin can exhibit a color similar to that of the surrounding tooth structure based on the structural color phenomenon. This study aims to evaluate the color adjustment potential (CAP) of a single-shade composite resin compared to conventional multi-shade composite resins in primary teeth. A single-shade composite resin and two conventional multi-shade composite resins were included in this study. Two types of specimens, a single specimen and a dual specimen, were evaluated. For single specimens, duplications of the primary second molar denture teeth were made using experimental composite resins. For dual specimens, cavities were prepared on the buccal surfaces of extracted primary second molars and restored with experimental composite resins. The L*, a*, and b* values were measured using a colorimeter for the extracted teeth and specimens. The mean ΔE_ab^* values for single and dual specimens and CAP were calculated. Bonferroni post-hoc analysis was performed to confirm the statistical significance between the ΔE_ab^* and CAP values of the experimental resins. Among the single specimens, the single-shade composite resin showed significantly higher ΔE_Single compared to other composite resins (<i>p</i> < 0.0167). There was no significant difference between ΔE_Dual for all experimental resins. The single-shade composite resin showed highest CAP compared to other multi-shade composite resins. A single-shade composite resin exhibited the most prominent color adaptability compared to other conventional multi-shade composite resins for primary second molars. A single-shade composite resin can simplify shade matching and provide esthetic outcomes for the restoration of primary second molars.

This study aimed to evaluate the effect of silver diamine fluoride (SDF) and potassium iodide (KI) on the formation of cariogenic biofilm and surface roughness in vitro. A total of 48 bovine dentin specimens with artificially induced caries were prepared and divided into 3 groups of 16: untreated control, SDF-treated, and SDF-treated followed by KI (SDFKI). Ten specimens from each group were used to observe microbial adhesion. Multispecies cariogenic biofilms including Streptococcus mutans , Lactobacillus casei , and Candida albicans were cultured on the specimens. Microbes were cultured for 24 hours, and the colony-forming unit was calculated. The remaining specimens were observed by atomic force microscope and scanning electron microscope (SEM). The number of bacteria was significantly lower in the SDF and SDFKI groups. KI did not inhibit the antibacterial activity of SDF significantly. SEM images showed particles generated after SDF and SDFKI application were deposited on the dentin, but there was no significant difference in surface roughness between the 3 groups. This study confirmed that SDF and SDFKI application did not have a significant effect on the surface roughness of dentin, but effectively inhibited the formation of the early cariogenic bacterial film after 24 hours compared to the control.

This study investigated the effects of silver diamine fluoride (SDF) and potassium iodide (KI) treatments on the acid resistance of dentin exposed to secondary caries. Sixteen bovine dentin specimens with artificially induced caries were assigned to the following four groups: untreated negative control, untreated positive control, SDF-treated (SDF), and SDF and KI-treated (SDFKI). Multispecies cariogenic biofilms containing <i>Streptococcus mutans</i>, <i>Lactobacillus casei</i>, and <i>Candida albicans</i> were cultured on the specimens for 28 days, except for the negative control group. Specimens from the negative control group were stored in phosphate-buffered saline for that period. After a cariogenic biofilm challenge, the degree of demineralization was evaluated using micro-computed tomography (micro-CT). As a result of data analysis using micro-CT, the demineralization depths of the negative control, positive control, SDF, and SDFKI groups were 149.0 ± 7 μm, 392.0 ± 11 μm, 206.0 ± 20 μm, and 230.0 ± 31 μm, respectively. The degree of demineralization was significantly reduced in the SDF and SDFKI groups compared with that in the untreated positive control group. There were no significant differences between the SDF and SDFKI groups. This study confirmed that SDF and SDFKI treatments increase the acid resistance of dentin to secondary caries. KI did not significantly affect the cariesarresting effect of the SDF.

The aim of this <i>in-vitro</i> study is to evaluate the effect of potassium iodide (KI) on erythrosine-mediated photodynamic therapy (PDT) against <i>Streptococcus mutans</i> biofilms. <i>S. mutans</i> ATCC 25175 was cultured to form a biofilm on a hydroxyapatite disk. After diluting erythrosine to 20 μM and KI to 10, 50, and 100 mM, respectively, PDT was performed. The number of surviving bacteria was calculated as colony forming units (CFU)/mL and the statistical significance of the difference between groups was confirmed by Bonferroni post-hoc analysis. Cell viability was visually evaluated using confocal laser scanning microscopy (CLSM). As a result of the experiment, a significant decrease (<i>p</i> < 0.05) in CFU was observed in the experimental groups in which PDT was performed after applying KI regardless of the concentration of KI. In addition, a significant reduction (<i>p</i> < 0.05) in CFU was observed in the experimental group to which 100 mM KI was applied compared to 10 mM KI. The same results were confirmed when observing CLSM. KI significantly improved the efficacy of erythrosine-mediated PDT on <i>S. mutans</i> biofilms at all concentrations. This may compensate for the low sensitivity of PDT to biofilm-state bacteria strains, but it is necessary to establish an optimal clinical protocol through further research.

This study evaluated the fluoride release of alkasite restorative material (ARM) and giomer penetrating the dentin adhesive layer. Twenty specimens were prepared for each restorative material, and dentin adhesive with uniform thickness was applied to half of them. The prepared specimens were placed in a polyethylene tube containing 2.0 mL of deionized water and deposited in a 37.0°C water bath for the study duration. The amount of fluoride release was measured on the 1st, 3rd, 7th, 14th, 21st, and 28th days after deposition. The dentin adhesive applied to the ARM and giomer could not completely block the fluoride release; however, it significantly reduced its amount. The cumulative amount of fluoride release of the ARM after 28 days was higher than that of the giomer regardless of the application of dentin adhesive.