Nestin and NG2 transgenes reveal two populations of perivascular cells stimulated by photobiomodulation.

Pericytes and glial cells are known to collaborate in dental pulp tissue repair. Cell-based therapies that stimulate these stromal components may be of therapeutic relevance for partially vital dental pulp conditions. This study aimed to examine the early effect of photobiomodulation (PBM) in pericytes from experimentally injured pulp tissue. To accomplish this, we used the Nestin-GFP/NG2-DsRed mice, which could allow the identification of distinct pericyte phenotypes. We discovered the presence of two pericytes subsets within the dental pulp, the Nestin + NG2+ (type-2) and Nestin- NG2+ (type-1). Upon injury, PBM treatment led to a significant increase in Nestin+ cells and pericytes. This boost was mainly conferred by the more committed pericyte subset (NestinNG2+ ). PBM also stimulated terminal blood vessels sprouting adjacent to the injury site while maintaining signs of pulp vitality. In vitro, PBM induced VEGF upregulation, improved dental pulp cells proliferation and migration, and favored their mineralization potential. Herein, different subsets of perivascular cells were unveiled in the pulp tissue. PBM enhanced not only NG2+ cells but nestin-expressing progenitors in the injured dental pulp.

Qualitative evaluation of scanning electron microscopy methods in a study of the resin cement/dentine adhesive interface.

Sample preparation and imaging techniques for scanning electron microscopy (SEM) of dehydrated dental samples can hinder the structural analyses. This study qualitatively evaluated images obtained with two different protocols of SEM preparation and analysis to assess the dentine adhesive interface. The crown and root dentine of 12 bovine incisors were subjected to cementation with the resin cement RelyX U100 or RelyX ARC/SBMP (n = 6). After storage for 7 days in a moist environment at 37 ± 1°C, the dentine samples were dehydrated in an ascending alcohol series, and three specimens from each group were coated with gold or carbon and examined in a high-vacuum (JEOL JSM-6360LV, 10 kV) or low-vacuum (FEI Quanta 200F, 15-30 kV) microscope. Images were obtained at magnifications between 50 and 2,000×, but with different working distances. The use of high vacuum for carbon and gold coating and SEM visualization led to cracks in the samples. A small number of cracks can be described in the specimens subjected to the low-vacuum technique. The protocol for SEM imaging in low vacuum was considered more appropriate for preservation of the integrity of the evaluated structures.