Hear about hormones, and your thoughts probably go to things like puberty, reproductive health, menopause, and the like. It’s doubtful that you’d think about your teeth and gums. Dental health and endocrine health seem worlds apart.
Except, of course, the body doesn’t really organize itself into categories that way.
Hormones are chemical messengers that travel through the bloodstream to help regulate various processes throughout the body, from inflammation and circulation to bone maintenance and saliva production. Naturally, some of those effects show up in the mouth.
You can see it during puberty, when changing levels of sex hormones can make the gums more reactive to plaque. Boys and girls alike may suddenly experience more redness, swelling, or bleeding, even if their diet or hygiene hasn’t changed much.
For women, the hormonal shifts of pregnancy can have a similar effect, sometimes dramatically. Rising estrogen and progesterone levels can amplify the gums’ inflammatory response to plaque, leading to the swollen, tender, bleeding gums we call pregnancy gingivitis.
And hormones can affect more than the gums. Testosterone and estrogen both play roles in maintaining bone, including the bone that supports your teeth. Hormonal changes can affect the delicate tissues that line the mouth. Later in life, declining estrogen levels may contribute to dry mouth, burning sensations, changes in taste, and loss of bone.
Hormones may even affect your jaw joints and the muscles that move them.
Here, the difference between the sexes is hard to miss. Temporomandibular disorders, or TMD, affect women far more often than men. Population studies put TMD symptoms at about twice the rate in women, while roughly 80% of patients seeking treatment are female. Symptoms often begin around puberty and are most common during the reproductive years.
Those estimates come from a fascinating study that just dropped in the Journal of Oral Rehabilitation, looking at the possible relationship between oral contraceptive use, hormone levels, and tenderness in the jaw joints and chewing muscles.
The study involved 111 healthy girls between the ages of 14 and 18. Twenty-six regularly took birth control pills, while the rest had never used hormonal contraception. None had been diagnosed with TMD at the start of the study.
As part of the research, the girls had both medical and dental exams and gave blood samples so researchers could get a picture of their hormonal environment. Specifically, they measured
- Estradiol, the primary form of estrogen during the reproductive years, which plays important roles in reproductive function, bone health, inflammation, and pain processing.
- Testosterone, which helps support bone and muscle and may also influence pain sensitivity. (Yes, girls produce testosterone, too. It’s not just a guy thing.)
- Sex hormone-binding globulin, or SHBG, a protein that binds to sex hormones and helps determine how much is freely available for the body to use.
Participants were also asked about headaches during the previous month, and each was examined for signs of TMD, such as tenderness in the joints and chewing muscles.
The differences between the two groups were striking.
There were hormonal differences, as you would expect. Compared to the girls who weren’t taking the pill, those who were had only about one-fifth as much estradiol and about half the amount of testosterone. Their SHBG levels were about three times higher, while free estradiol was about 14 times lower.
The TMJ health differences, however, were less expected, with about 42% of the girls taking oral contraceptives experiencing tenderness when their jaw joints or chewing muscles were lightly touched. That was found in just 18% of the girls who weren’t taking them.
Headaches were considerably more common among the birth control users, too. A whopping 92% reported having had a headache during the previous month, compared with 65% of the other girls.
Even after accounting for age and body mass index (BMI), oral contraceptive use remained associated with about three times the odds of tenderness in the jaw joints and chewing muscles and around six times the odds of having reported a headache.
The study authors suggest that the dramatic differences in estradiol may help explain the greater tenderness they found among the girls taking oral contraceptives. They explain that estrogen receptors are found in the trigeminal ganglion — part of the nervous system that carries sensation from the face — as well as in the chewing muscles and tissues of the TMJ itself. There, estradiol helps modulate the sensitivity of pain-sensing nerves and the release of substances involved in inflammation.
The authors propose that by suppressing the body’s own production of estradiol, oral contraceptives may reduce some of estrogen’s pain-dampening effects, both in the brain and nervous system and out in the tissues themselves. The result could be a lower threshold for tenderness in the jaw joints and muscles.
Estradiol may not be the only hormone involved, either. The researchers also point to earlier work in adolescent boys that linked lower levels of free testosterone with greater tenderness in the jaw joints and chewing muscles. Since testosterone was substantially lower among the birth control users in the current study, the authors suggest that the two hormones may be affecting pain sensitivity through overlapping pathways.
All of which brings us back to where we started: The body doesn’t organize itself into the tidy categories we do.
Neither do medications always limit their effects to the condition they’re meant to address. They can alter hormones, saliva, inflammation, bone metabolism, muscle function, and any number of other processes throughout the body. That’s true whether the patient is male or female, 15 or 50.
So when jaw pain or tenderness develops without an obvious explanation, the joint itself may be only part of the story. Medications, hormonal changes, and other aspects of a patient’s health may provide clues that aren’t apparent from looking at the jaw alone.
Sometimes, understanding why a jaw hurts means looking well beyond the jaw.