Assessing the Oral Microbiome in Women of Reproductive Age: A Narrative Review

TL;DR

This review explores how the oral microbiome in women of reproductive age is studied and how it is influenced by hormonal changes and other factors.

Contribution

The paper highlights the importance of methodological considerations in studying the oral microbiome, especially in relation to hormonal fluctuations.

Findings

Oral microbiome assessment relies on genetic sequencing due to the difficulty of culturing many species.

Estrogen can influence immune responses and worsen gingival inflammation in women.

Hormonal contraceptives and lifestyle factors like diet and smoking affect the oral microbiome composition.

Abstract

The oral microbiome may be an indicator of oral pathologies and hormonal fluctuations. Consequently, the proper identification of methods for studying microbial factors is essential. Because more than half of the components of the oral microbiome belong to species that are very difficult or even impossible to cultivate in the laboratory, the assessment of the oral microbiome nowadays is based on genetic sequencing, using techniques such as DNA hybridization, 16S rRNA sequencing, and metagenomics, mainly analyzing saliva and subgingival plaque. Variations in results may be caused by differences in sample type, analysis methods, accuracy in determining cycle phases, and biases introduced by DNA extraction techniques and technical variations. Choosing the right primers for the 16S rRNA gene and reference databases (like HOMD, Greengenes2) is essential for accurately identifying microorganisms. Metagenomic sequencing offers greater taxonomic and functional detail, but it is costlier and presents bioinformatics challenges, including contamination with human DNA. When the patients under study are women, we have to take into consideration the cyclical changes in the menstrual cycle. Studies suggest that estrogen influences local immune and inflammatory responses and can worsen existing gingival inflammation. Certain oral bacteria can even utilize estradiol and progesterone as growth factors. The composition of the oral microbiome is also affected by hormonal contraceptives, carbohydrate intake, smoking, age, body mass index, genetics, and oral hygiene—all factors that need to be controlled for in future studies. Interpreting the biological significance of the reported cyclic changes requires careful examination of the specific methods used in each study.

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