I don't think buying expensive electric tooth brush makes any difference compared to buying less expensive ones. I would be careful to take any advise that points me directly to a specific PRODUCT, from specific COMPANY. Fortunately there are more one brands, in the market, to choose from. I am not sure about yellow coating on your tongue; I used to have, but have been on many diet, and consulted many therapies. I forgot whether from spleen or from candida? Perhaps some one else more knowledable address that. Good luck.