Cemal Ucer considers how the differences between men and women can impact oral health.
Sex is one of the most basic differentiating factors between patients, and has been shown to affect health outcomes and disease in myriad ways. Despite this, a great deal of medical research has not adequately accounted for even this basic distinction between patients, treating women as essentially interchangeable with men. Women experience adverse drug reactions nearly twice as often as men, and a major component of this is likely to be caused by historical and contemporary failures in adequately enrolling women in clinical trials, or even considering sex in analysis.
Physiological differences between the sexes can affect immune system function and disease susceptibility. Gender roles and expectations can also markedly affect behaviour and psychological wellbeing, which in turn can have health consequences. For example, smoking prevalence is notably higher among men (in the UK, 15.9 per cent of men smoke versus 12.5 per cent of women). Other sociological factors can intertwine or exist independently alongside gender. To use the smoking example again, among the British population cultural/ ethnic background plays a modifying role, with, for instance, comparatively few Asian women taking up smoking (on average 2.9 per cent women and 13.9 per cent men). Socioeconomic class is a major modifier of many aspects of life, not least health outcomes and morbidity, and gender has a very complex relationship with socio-economic status.
Policy oversights relating to sex have also put men’s health at risk. For example, the human papillomavirus (HPV) vaccine was historically only given to girls. The reasoning being that because heteronormativity was assumed, men would be indirectly protected, allowing for a cheaper, less comprehensive vaccination programme. It is now known that some strains of HPV are strongly linked to a range of cancers that men are susceptible to, including anal cancer, cancer of the penis and cancers of the head and neck. The NHS now also vaccinates boys born after September 1, 2006, during secondary education (those who missed vaccination during school can access it through the NHS until their 25th birthday). However, this has still left several generations of men at increased risk of eventually developing potentially fatal and lifechanging cancers. Many patients may benefit from being informed that men who have sex with men (MSM) and trans women, up to and including 45 years old, are now able to receive HPV vaccination on the NHS. This service is freely offered at sexual health and HIV clinics in England.
Statistically, women are at greater risk of developing caries, and this appears to occur from puberty (12 years old and onwards). The discrepancy is not found during the primary dentition stages, indicating that there is some factor or factors that come into play during this time, but it is contentious within the literature as to what these are. Behavioural explanations are often forwarded, however, female participants appear to consume fewer sweets and soft drinks, whilst also brushing their teeth more frequently than male counterparts. Given that sugar exposure and oral hygiene are classically regarded as the key factors in caries development, this would suggest that something else is occurring.
Contrastingly, men appear to be at greater risk of developing periodontitis (approximately 57 per cent men compared to 37 per cent women), with the disparity highest in cases of severe periodontitis. Unfortunately, key classical studies of periodontal disease were conducted with exclusively male samples, which raises questions on how much their results can be generalised. As periodontitis is driven by a complex interaction between infectious microbial activity and host immune response, it is possible, even likely, that sexual dimorphism in immune response plays a role in relative risk. Differences in microbiota between sexes may also be a factor.
On the macro level, some structural differences are readily apparent, with the mandible, for example, usually exhibiting significant dimorphism between sexes. A CBCT study has found that women typically have a notably thicker Schneiderian membrane, perforation of which is a relatively common complication in certain implant and bone augmentation procedures. Some differences extend down to the microscopic level, with recent research demonstrating that sexual dimorphism appears to affect cellular responses in ways that could impact the success of numerous treatments, including dental implants. Whilst osteointegration can broadly be reliably achieved, cells from male and female patients react differently in response to various hormones and growth factors. Further study in this area may improve osteointegration outcomes.
It is critical that we move away from inaccurate universalist models, that treat patients as fundamentally interchangeable, and towards more tailored treatments. We have a long way to go to redress historical research biases, but we can already see some of the diagnostic and treatment benefits to accomplishing this. The moral basis is self-evident, but doing so also brings a tangibly more accurate and actionable picture of dental realities into focus.