By Svante Twetman, DDS, Professor Emeritus, PhD, Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen Denmark T he oral cavity harbors a complex microbial ecosystem where symbiotic interactions and the host’s immune system supports oral health. The microbiome is however vulnerable for ecological perturbations and the balanced proportion of various bacteria is affected by lifestyle factors such as sugar consumption, tobacco smoking, oral hygiene and use of antibiotics. 1 The composition can shift to dysbiotic conditions with a reduced diversity and abundance of disease-related saccharo-or proteolytic pathogens (Fig. 1). Likewise, the onset of fixed orthodontic appli-ances can challenge the healthy balance of the oral ecosystem and induce an unfavorable shift of the dental microbiota. 2 It is therefore important to prevent such dysbiosis in order to avoid subsequent adverse effects. The decisive role of the oral micro-biome in health and disease has paved the way for probiotic bacteria in the management of oral diseases. 3 To date, systematic reviews have covered the efficacy for early childhood caries prevention, 4 management of periodontal diseases, 5 oral candidia-sis 6 and halitosis. 7 This article summarizes the concept of probiotics in general dentistry and reviews the beneficial effects in general dental and orthodontic practices based on randomized placebo-controlled trials in humans with fixed appliances. What Are Probiotics? The definition of probiotics (Greek, meaning “for life”) is “live microorganisms which when adminis-trated in adequate amounts confer a health benefit on the host.” The most common strains derive from the Lactobacillus and Bifidobacterium genera and Lacticas-Fig. 1: Principal drawing of a stress-related shift in the oral ecosystem from a health-associ-ated symbiotic biofilm (A) to a dysbiotic condition with reduced diversity and abundance of pathogens (B). The shift can be induced by the onset of fixed orthodontic appliances, amending the structure and function of the oral microflora. Daily intake of probiotic bacteria can aid to restore the balance. 14 Summer 2021 JAOS
Journal of the American Orthodontic Society Summer 2021: Page 14
