Dysbiosis in the oral environment may play a role in the etiopathogenesis of oral squamous cell carcinoma (OSCC). This review aims to summarize the current knowledge about the association of oral microbiota with OSCC and to describe possible etiopathogenetic mechanisms involved in processes of OSCC development and progression. Association studies included in this review were designed as case–control/case studies, analyzing the bacteriome, mycobiome, and virome from saliva, oral rinses, oral mucosal swabs, or oral mucosal tissue samples (deep and superficial) and comparing the results in healthy individuals to those with OSCC and/or with premalignant lesions. Changes in relative abundances of specific bacteria (e.g., Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus sp.) and fungi (especially Candida sp.) were associated with OSCC. Viruses can also play a role; while the results of studies investigating the role of human papillomavirus in OSCC development are controversial, Epstein–Barr virus was positively correlated with OSCC. The oral microbiota has been linked to tumorigenesis through a variety of mechanisms, including the stimulation of cell proliferation, tumor invasiveness, angiogenesis, inhibition of cell apoptosis, induction of chronic inflammation, or production of oncometabolites. We also advocate for the necessity of performing a complex analysis of the microbiome in further studies and of standardizing the sampling procedures by establishing guidelines to support future meta-analyses.

Severe Early Childhood Caries (sECC) is a multifactorial disease associated with the occurrence of specific oral microorganisms and other environmental, behavioral, and genetic factors. This study aimed to construct a multivariable model including the occurrence of Candida spp. and selected behavioral factors (length of breastfeeding, serving sweet beverages and beginning of brushing child’s teeth) to determine their relationships to the occurrence of sECC.In this case-control study 164 children with sECC and 147 children without dental caries were included. MALDI-TOF MS and multiplex qPCR were used to identify Candida spp. and selected bacteria in dental plaque samples, respectively. A questionnaire on oral hygiene, diet, and children’s health was filled in by the parents.The constructed multivariable logistic regression model showed an independent influence of the microbial and behavioral factors in sECC etiopathogenesis. The occurrence of C. albicans and C. dubliniensis was associated with higher odds of sECC development (odds ratio, OR: 9.62 and 16.93, respectively), together with breastfeeding of 6 months or less (OR: 2.71), exposure to sweet beverages (OR: 3.77), and starting to brush child’s teeth after the 12th month of age (OR: 4.10), all statistically significant (p < 0.01).Considering the high occurrence of C. albicans and C. dubliniensis in dental plaque in children with sECC, we propose them as “keystone pathogens” and risk factors for sECC. The models showed that presence of specific species of Candida in dental plaque may be a better descriptor of sECC than the mentioned behavioral factors.

Objectives Dental caries is a widespread multifactorial disease, caused by the demineralization of hard dental tissues. Susceptibility to dental caries is partially genetically conditioned; this study was aimed at finding an association of selected single nucleotide polymorphisms (SNPs) in genes encoding proteins involved in amelogenesis with this disease in children. Materials and methods In this case–control study, 15 SNPs in ALOX15, AMBN, AMELX, KLK4, TFIP11, and TUFT1 genes were analyzed in 150 children with primary dentition and 611 children with permanent teeth with/without dental caries from the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) cohort. Results Dental caries in primary dentition was associated with SNPs in AMELX (rs17878486) and KLK4 (rs198968, rs2242670), and dental caries in permanent dentition with SNPs in AMELX (rs17878486) and KLK4 (rs2235091, rs2242670, rs2978642), (p ≤ 0.05). No significant differences between cases and controls were observed in the allele or genotype frequencies of any of the selected SNPs in ALOX15, AMBN, TFIP11, and TUFT1 genes (p > 0.05). Some KLK4 haplotypes were associated with dental caries in permanent dentition (p ≤ 0.05). Conclusions Based on this study, we found that although the SNPs in AMELX and KLK4 are localized in intronic regions and their functional significance has not yet been determined, they are associated with susceptibility to dental caries in children. Clinical relevance AMELX and KLK4 variants could be considered in the risk assessment of dental caries, especially in permanent dentition, in the European Caucasian population.

Background This pilot study aimed to investigate how fixed orthodontic appliances simultaneously applied on the upper and lower arches affect the oral environment in the medium term. Methods The oral status of 30 orthodontic patients was evaluated using the number of decay-missing-filled teeth (DMFT), plaque (PI), and gingival indices (GI) before bonding of fixed orthodontic appliances (T0) and during the therapy (T1). Besides, the gingival crevicular fluid (GCF) and a dental plaque were collected. Samples were analyzed for selected Candida sp. and for 10 selected oral bacteria using mass spectroscopy and multiplex polymerase chain reaction, respectively. Results In 60% of patients, deterioration of the oral status (demonstrated by the increase in PI) was recorded (p < 0.05). Moreover, the changes in PI correlated with those of GI (p < 0.001). At the T1 time point, the mean representation of Actinomyces sp. in the total prokaryotic DNA in GCF and dental plaque of individual patients increased compared to T0 (p < 0.05). The probability of finding any of the 7 selected periodontal bacteria combined with Candida sp. was 10 times higher in patients in whom PI deteriorated between T0 and T1 (p < 0.01). Conclusions Changes in the oral microbial diversity and an increase in PI were observed in the medium term after bonding of orthodontic appliance. Our study highlights the importance of a complex approach in this type of research as the association between clinical characteristics and combined microbial parameters is higher than when evaluated separately.

Toxic epidermal necrolysis (TEN) represents a rare drug‐induced autoimmune reaction with delayed‐type hypersensitivity that initiates the process of developing massive keratinocyte apoptosis, dominantly in the dermoepidermal junction. Although the etiopathophysiology has not yet been fully elucidated, the binding of Fas ligand (FasL, CD95L) to the Fas receptor (CD95) was shown to play a key role in the induction of apoptosis in this syndrome. The knowledge of the role of immunoglobulin G (IgG) in inhibition of Fas‐mediated apoptosis contributed to the introduction of i.v. Ig (IVIg) in the therapy of TEN patients. Despite great enthusiasm for this therapy at the end of the 1990s, subsequent studies in various populations and meta‐analyses could not unequivocally confirm the efficacy of the IVIg‐based treatment concept. Today, therefore, we are faced with the dilemmas of how to adjust therapy of TEN patients most effectively, which patients could benefit from IVIg therapy and what dose of the preparation should be administrated. The ground‐breaking question is: do the host genetic profiles influence the responsiveness and side‐effects of IVIg therapy in TEN patients? Based on recent pharmacological, immunological and genetic findings, we suggest that the variability of IVIg therapy outcomes in TEN patients may be related to functional variants in Fas, FasL and Fc‐γ receptor genes. This novel concept could lead to improved quality of care for patients with TEN, facilitating personalized therapy to reduce mortality.