Women and oral health: views from periodontology and gynaecology

There is an increasing realisation of the impact of the human biome on health and disease, and the oral cavity is one of the densest microbial environments in the body. Despite this, there remains a lack of understanding regarding oral health and disease and the possible contribution of female hormones.

Across a diverse range of cultures women appear to have a higher incidence of dental caries.¹ The underlying risk factors have been postulated to include the earlier eruption of permanent dentition in girls (and therefore longer exposure to cariogenic risk), the differing diets of women and men, and pregnancy.  Pregnancy has long been thought to be a major risk factor for gingivitis and caries, but there is uncertainty about the underlying causes. This raises the question of the impact of female hormones on oral health.

At puberty, girls start to experience the production of oestrogen and, later, progesterone from ovarian egg development. This continues throughout their reproductive life with the menstrual cycle and with the use of hormonal contraceptives. In vitro fertilisation protocols utilise high levels of gonadotrophins to allow the development of multiple eggs, each of which produces oestrogen. This results in super-ovulation and correspondingly elevated levels of oestrogen for the three to four weeks of treatment. But it is pregnancy that remains the time associated with the highest levels of both oestrogen and progesterone, and it has long been thought to be associated with an increased risk of both dental caries and gingivitis.

During pregnancy, progesterone is the dominant hormone required for implantation, maintenance of pregnancy, and the suppression of pre-term labour. Progesterone also acts to supress the maternal immunologic response, important in preventing maternal rejection of ‘foreign’ foetal antigens. This reduction in natural immunity during pregnancy means that pregnancy is a period of relative immunosuppression and there is greater morbidity and risk of death from infections including influenza A and SARS-CoV-2. This reduction in natural immunity may increase susceptibility to bacterial infection and there have been some studies showing an increase in cariogenic strains of bacteria during pregnancy.

There is a growing body of evidence that oestrogen is associated with a higher incidence of caries whereas androgens (male hormones) are not. Receptors for both oestrogen and progesterone have been shown in the salivary glands and gingival tissue,^{2, 3} indicating that these tissues respond to hormonal influence. Oestrogen has been demonstrated to affect both the composition – with a reduction in buffering capacity – and the flow rate of saliva, thus predisposing to increased bacterial growth and caries.

More recently, there is a growing understanding that poor oral health and active gingivitis in pregnant women is associated with an increased risk for pre-term and low-birth-weight babies, as well as the development of high blood pressure (pre-eclampsia) during pregnancy. Bacteria originating from the oral cavity have been found in the placenta and in the amniotic fluid surrounding the baby.

In summary, the hormonal milieu appears to affect a woman’s susceptibility to periodontal disease with a particular risk around the time of pregnancy. The higher incidence of caries in women implicates an impact of endogenous sex-steroid hormones on oral health at puberty, menstruation, pregnancy, menopause, and with the use of the contraceptive pills and hormone-replacement therapy.  These factors are important for understanding and manipulating oral health and disease in women.

However, there is evidence that maintaining good oral hygiene and plaque control can mitigate the impact and risks of hormonal fluctuation, and a greater understanding of this by both women and medical professionals will improve outcomes.

References

<sub>1. Lukacs JR, Largaespada LL. Explaining sex differences in dental caries prevalence: saliva, hormones, and "life-history" etiologies. Am J Hum Biol. 2006 Jul-Aug;18(4):540-55. doi: 10.1002/ajhb.20530. PMID: 16788889.
2. Vittek J, Munnangi PR, Gordon GG, Rappaport S, Southren AL. Progesterone “receptors” in human gingiva. IRCS Med Sci 1982:  10:  381–384.
3. Vittek J, Hernendez MR, Wennk EJ, Rappaport SC, Southren AL. Specific estrogen receptors in human gingiva. J Clin Endocrinol Metab 1982:  54:  608–612.</sub>

Ali Çekici: The role of sex hormones on periodontal tissues at the key stages of a woman’s life