REVIEW Oral microbial biofilms: an update Seyed Ali Mosaddad 1 & Elahe Tahmasebi 1 & Alireza Yazdanian 2 & Mohammad Bagher Rezvani 3 & Alexander Seifalian 4 & Mohsen Yazdanian 1 & Hamid Tebyanian 1 Received: 11 June 2019 /Accepted: 14 July 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Human oral cavity (mouth) hosts a complex microbiome consisting of bacteria, archaea, protozoa, fungi and viruses. These bacteria are responsible for two common diseases of the human mouth including periodontal (gum) and dental caries (tooth decay). Dental caries is caused by plaques, which are a community of microorganisms in biofilm format. Genetic and peripheral factors lead to variations in the oral microbiome. It has known that, in commensalism and coexistence between microorganisms and the host, homeostasis in the oral microbiome is preserved. Nonetheless, under some conditions, a parasitic relationship dominates the existing situation and the rise of cariogenic microorganisms results in dental caries. Utilizing advanced molecular biology techniques, new cariogenic microorganisms species have been discovered. The oral microbiome of each person is quite distinct. Consequently, commonly taken measures for disease prevention cannot be exactly the same for other individuals. The chance for developing tooth decay in individuals is dependent on factors such as immune system and oral microbiome which itself is affected by the environmental and genetic determinants. Early detection of dental caries, assessment of risk factors and designing personalized measure let dentists control the disease and obtain desired results. It is necessary for a dentist to consider dental caries as a result of a biological process to be targeted than treating the consequences of decay cavities. In this research, we critically review the literature and discuss the role of microbial biofilms in dental caries. Keywords Human oral microbial . Biofilms . Dental caries . Periodontal Introduction Like other complicated multicellular eukaryotes, the human being is not an independent organism. Various microbial sym- bionts and their genomes are in association with the biological functioning of the human body. The microbial population heavily colonizes in the inner and outer surfaces of our bodies and develop an operative organ, which is crucial to our health and physiology. The bacterial populations of the mouth are extremely complex with approximately 1000 species. They have been estimated to be the second most complicated in the body, after the colon [1]. The treatment of dental caries in clinical practice is usually referred to as the restoration of the hard tissues of the teeth according to the functional and aesthetic needs. However, this cannot be considered as disease treatment, but a cure its consequences. Contemporary Dental Clinical (CDC) practice is entirely focused on restorative treatment. In clinical practice, a commonly used method of caries treatment includes removing the infected tissues in or- der to stop the further progression of the disease. It is well- known that there is no permanent filling, but gradually, the repaired sections develop little spaces for microbial activities. As a result, the small filling should be replaced with the larger one and tissues of the teeth should be removed more and more. Restoration practice is mainly followed by endodontic treatment, which leads to dental prosthetic dentistry. However, this is not the final stage in the pathology of the tooth. If the tooth is extracted by surgery due to some complications, the Seyed Ali Mosaddad and Elahe Tahmasebi contributed equally to this work. * Mohsen Yazdanian drmyazdanian@yahoo.com * Hamid Tebyanian tebyan.hamid@yahoo.com 1 Research Center for Prevention of Oral and Dental Diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran 2 Department of Veterinary, Science and Research Branch, Islamic Azad University, Tehran, Iran 3 Department of Operative Dentistry, Shahed University, Tehran, Iran 4 Nanotechnology and Regenerative Medicine Commercialization Centre (Ltd), The London Bioscience Innovation Center, London, UK European Journal of Clinical Microbiology & Infectious Diseases https://doi.org/10.1007/s10096-019-03641-9