Background The perception that there is a surplus of dentists may be an opportunity to explore attractive career options in dentistry in Japan. Methods A self-administered questionnaire was mailed to 2,114 graduates of a private dental school in Japan. We asked about the perception of oversupply, rated by a visual analogue scale, work environment factors, potential areas of dentistry and necessary medical subjects for their dental practice. The association of a strong perception of dentist oversupply with work environment factors, dental areas and medical subjects was examined by multivariate logistic regression analyses. Results The response rate was 66%, and data from 1,203 community dentists were analysed. Most respondents (76%) perceived either a strong or very strong surplus of dentists. A very strong perception was significantly associated with work environment factors, including practising in large cities and earning the second lowest of four levels of annual income, but no further associations were found with either the number of patients treated or with the other two ranges of income. This perception was negatively associated with the number of necessary medical subjects, specifically otorhinolaryngology, but no significant association was seen with the number of potential areas of dentistry. Conclusions The negative correlation between the aspiration to acquire medical knowledge and the perception of dentist oversupply under the circumstance of the possibly excessive perception among community dentists invites further research on the benefits of teaching oral medicine to graduate entry students to build future working satisfaction.