I am not sure if this is what you're looking for, but as I understand you're looking for a stain to detect viable cells? - We use Alamar blue (resazurin-based assay) (life tech./invitrogen) for viability. This is good for larger changes, however, if you want to see smaller changes I recommend CellTiter-Glo from promega which is more sensitive. Both assays detect metabolically active cells.

Besides the usually used Trypan Blue also can be used: methylene blue (absorptive stain), indigo carmine (contrast stain), Cresyl violet; Erythrosine (Red No 3), Eosin (both are exclusion dyes), Propidium iodide; 7-aminoactinomycin D, Alizarin Red, fluorescent dimethyltin(iv)-alizarin red S complex....all depending on the exptl. necessity you have. Even injections of lead acetate as an intravital stain of calcification sites have been described. Perhaps interesting to you also would be reading: Time-Saving Benefits of Intravital Staining

@ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2901106/

Best wishes and regards,

Dear Antony, I thought about the initial question "check the vitality of PDL fibers for tooth and dental pulp cells". So this means that you are using Periodontal Ligament(s) = PDL fibers as a substratum for grwoing tooth and dental pulp cells? Right or wrong? Or would it be rather "multipotent postnatal stem cells from human periodontal ligament or Periodontal Ligament Stem Cells (PDLSCs) " what you would like to test for vitality? Fibers or cells? Thank you for your kind clarification....best regards, Wolfgang

Dear Wolfgang Muss, thank you for your answer......need simple method to check PDL cells vitality after cryopreservation of tooth before re-implantation of tooth into the alveolar bone socket..... to ensure PDL attachment occurs.... otherwise will result in ankylosis due to loss of cell vitality......the stains should not damage the cells. Thank you for your time.