A periodontitis vaccine could rank with one for cancer not for securing life expectancy but for promoting quality of life, because periodontal disease is the primary cause of the loss of facial esthetics and oral function in adults. Besides, we already know that nearly two-thirds of the world's population suffers from periodontal disease, which may affect the aggravation of systemic disease. Up to the present, attempts at periodontal vaccine development have turned out to be unsuccessful. This may be due to the polymicrobial nature of dental biofilm and the complexity of interaction among the host and various environmental factors. However, periodontal vaccine development is worthwhile for the eradication of the global burden of the morbidity of periodontitis. This should eventually enhance the situation of debilitating disease including atherosclerosis, diabetes, and preeclampsia. In this issue, we have a review on vaccination for periodontal disease which deserves to be read, in addition to four original articles and two clinical reports.

Mr. Shanteau encourages us with a quote from Booker T. Washington: "Success is not defined by the number of victories you achieve, but by the mountains you overcome." Considering this, we should be expecting a successful periodontal vaccination in the future and likewise be Waiting for Godot, which is the hope not from God but from mankind, no matter how hard it might be.