The objective of the study was to evaluate the color stability of 8 recently developed resin composites when exposed to various staining agents. Six disc-shaped specimens made out of 8 resin composite materials were immersed in artificial saliva, coffee, coke, tea, orange juice and red wine. The initial color (T0) of the 288 specimens was assessed by a calibrated reflectance spectrophotometer (SpectroShade, MHT) over a black as well as a white background. All specimens were kept in an incubator (INP-500, Memmert GmbH) at 37 °C for 4 weeks. Colorant solutions were changed every 7 days to avoid bacteria or yeast contamination. After 4 weeks of storage in the colorants (T1), spectrophotometric measurements were repeated and ΔE00 was calculated. When analyzed over a white background, the mean ΔE00 values varied from 1.5 (Venus Diamond) to 52.4 (Miris 2). When analyzed over a black background, the mean ΔE00 values varied from 0.8 (Venus Diamond) to 40.0 (ELS). Significant differences were detected when comparing values at T0 and T1 (ΔE00) for both backgrounds (Anova and Fisher’s LSD post hoc test). Resin composite materials do behave in a significantly different way (p value < 0.01) when exposed to various staining solutions.

Stem cells (SCs) receive inductive cues from the surrounding microenvironment and cells. Limited molecular evidence has connected tissue-specific mesenchymal stem cells (MSCs) with mesenchymal transit amplifying cells (MTACs). Using mouse incisor as the model, we discover a population of MSCs neibouring to the MTACs and epithelial SCs. WithNotchsignaling as the key regulator, we disclose molecular proof and lineage tracing evidence showing the distinct MSCs contribute to incisor MTACs and the other mesenchymal cell lineages. MTACs can feedback and regulate the homeostasis and activation of CL-MSCs through Delta-like 1 homolog (Dlk1), which balances MSCs-MTACs number and the lineage differentiation.Dlk1’s function on SCs priming and self-renewal depends on its biological forms and its gene expression is under dynamic epigenetic control. Our findings can be validated in clinical samples and applied to accelerate tooth wound healing, providing an intriguing insight of how to direct SCs towards tissue regeneration.