Urban legends: facts and myths in oral diseases

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In the last 20 years we have observed incredible devel-opments in Medicine and Dentistry owing to theproliferation of journals and a huge increase in theinformation available for any single topic. In particular,Internet access dramatically changed the availability ofmedical information, and the patients use this as one oftheir primary sources of healthcare information. Thesetwo developments have culminated in the increasingimportance of so-called Evidence-based Medicine⁄Den-tistry (EBM⁄D) (Sackett et al, 1996). The essence of theevidence-based approach is to use the evidence from allsources to provide the best outcome for the patient.Nevertheless, some evidence is better, stronger, or morevalid than the rest (Richards, 2003), and yet, only aminority of decisions made in health services are basedon good evidence. Conversely, consistent amounts ofknowledge that we generally assume to be trustworthyor robust are not supported by strong scientific data.These common beliefs are almost always plausible, ofteneven attractive, and repetitions in articles and textbooksincrease their importance and credibility, just like urbanlegends.Urban Legends or Myths are indeed not uncommon inrigorous disciplines such as both science at large andmedicine and dentistry in particular (Galler, 2006;Conn, 2008; Koretz, 2008; Sansone and Sansone,2008; Francl, 2010). Medical⁄dental urban legends aretypically triggered by an article or meeting report, orsometimes, they arise from apparently common clinicalexperiences (Galler, 2006). These legends may be relatedto old information trusted by default and never reviewedin depth. They may have some kernel of truth to them,but the ability to rapidly disseminate information to vastnumbers of people via Internet has drastically shortenedthe time it takes for unproven observations to becomeurban legends (Conn, 2008).Although patients may bemore keen than health care workers to entrust medicalurban legends, these can also spread among specialists’.An example of medical urban legend was the belief thatmeasles, mumps, and rubella (MMR) vaccination orexcessive thimerosal (which is an ethyl mercury–containing preservative used in selected vaccines in the1990s) exposure may be causally linked to the occur-rence of autism (Shevell and Fombonne, 2006; Fitzpa-trick, 2007; Scahill and Bearss, 2009). A similar mercurypoisoning’ hypothesis has linked amalgam restorationsto disorders such as Alzheimer’s disease or multiplesclerosis (Wahl,2001; Aminzadeh and Etminan, 2007).However, medical⁄dental urban legends are sometimesmore subtle and difficult to be recognized but whenidentified, they can ultimately inspire us to improve(Francl, 2010).Indeed, one of the fundamental steps in the EBM⁄Dprocess is the identification of clinical problems. Unfor-tunately, the vast majority of published reviews arepoorly focused on addressing specific queries or aremainly devoted to therapeutic issues. With this in mind,Oral Diseases will present a series of critical reviews inoral medicine aimed at distinguishing between Facts(based on the best available evidence) and Myths (basedon personal opinion, outdated⁄distorted information orno data at all). The first step of this process was to findgeneral topics routinely encountered by oral medicineand oral pathology specialists. The chosen topics are thefollowing:1 recurrent aphthous stomatitis2 Sjogren’s syndrome3 pemphigus vulgaris4 candidosis5 oral leukoplakia6 lichen planus7 mucous membrane pemphigoid8 orofacial granulomatosis9 HIV infectionAfterward, specific questions regarding each topicwere identified. While specific to oral medicine and oralpathology, some of the topics are clinically common fordermatologists, otolaryngologists, general physicians,gastroenterologists, rheumatologists, and infectious dis-eases specialists. The reviews are especially focused oncontroversial topics or established knowledge that has a