Dpto. Odontología

Introduction. Breast cancer is the world’s most prevalent malignancy, with an increasing incidence and a predisposition for postpubertal females from all cultural and ethnic backgrounds. More recently, oral Fusobacterium nucleatum species have been observed in cancerous human breast tissue, drawing attention to the role of microbes in cancer pathogenesis. Objectives. Investigating oral Fusobacterium nucleatum species as potential biomarkers for female-speci2c breast cancer. Methods. A systematic search in )e Central Register of Controlled Trials, EMBASE, EBSCO, NCBI, and MEDLINE databases was undertaken from the 1st January, 1983–31st March, 2022. Articles included were in English and based on women between the ages of 18–96 years with con2rmed gingivitis/periodontal disease and breast cancer diagnoses from registered specialists. Authors extracted data independently, and a meta-analysis of risk estimations measuring associations between oral Fusobacterium nucleatum species and female-speci2c breast cancer was elucidated via calculated relative risks and 95% con2dence intervals. Results. AXIS tool analysis revealed 78.70% of articles with a positive correlation between oral Fusobacterium nucleatum and female-speci2c breast cancer. )e risk of breast cancer development increased with signi2cant levels of oral Fusobacterium nucleatum due to gingivitis/ periodontitis (relative risk � 1.78, 95% con2dence interval � 1.63–1.91). Low-moderate statistical heterogeneity was found (I2 � 41.39%; P � 0.02), and the importance of periodontal status on breast cancer pathogenesis was determined (relative risk � 1.24, 95% con2dence interval � 1.01–1.30). Conclusions. Oral Fusobacterium nucleatum species are a risk factor for breast cancer development, thus elevating their biomarker potentiality.

Extrinsic black dental staining is an external dental discoloration of bacterial origin, considered a special form of dental plaque. Currently, there is no definitive therapeutic option for eliminating black stain. This study employed 16S rRNA metagenomics to analyze black stain and white-plaque samples from 27 adult volunteers. Study objectives were to: describe the microbial diversity of adult black stain samples; characterize their taxonomic profile; compare the microbiomes of black stain versus white-plaque from adult volunteers and propose a functional map of the black stain microbiome using PICRUSt2. The black stain microbiome was poorer in species diversity as compared to white-plaque. The five most abundant genera in black stain were Capnocytophaga, Leptotrichia, Fusobacterium, Corynebacterium and Streptococcus. Functional analysis of microbial species revealed conserved and consistent clustering of functional pathways within and between black stain and white-plaque microbiomes. We describe enrichment of heme biosynthetic pathways in black stain. Our results suggest that the dysbiosis in black stain resembles “orally healthy” communities. The increased abundance of heme biosynthetic pathways suggests that heme-dependent iron sequestration and subsequent metabolism are key for black stain formation. Further research should decipher the regulation of heme biosynthetic genes and characterize the temporal sequence leading to colonization and dysbiosis.