Recently, while reviewing the profile of the patients we see with persistent TMD problems, what we already suspected was confirmed: approximately 77% of patients in active care are women. Moreover, nearly 90% of the patients receiving BOTOX® injections for stubborn jaw muscle pain were women as well.
Although the discrepancy in the female/male ratio has long been recognized, it is worthwhile to examine the current theories explaining this gender gap.
What The Research Reveals
From a broad perspective, research exploring the influence of gender on persistent pain problems throughout the body has revealed that women are 30% more likely to experience more intense pain, more life-impacting pain, and less responsiveness to treatment than men. Within the narrow category of TMD pain problems, three areas have been most extensively studied and help explain the gender gap that we see.
- Hormonal Influences on Pain, Ligaments & Muscles
- Psychosocial Factors, including Catastrophizing
- Brain Interpretation of Pain
Let’s analyze each area individually, recognizing that a variety of factors often come into play.
Hormonal Influence on Pain
Understanding the influence of hormones on TMD-related pain starts with an appreciation that estrogen plays a vital role. Evidence suggests that estrogen is involved in regulating the inflammatory process within the temporomandibular joint and appears to influence the sensitivity of pain receptors and pain signaling. However, the fluctuation of estrogen levels is important to consider. Therefore, the age of the patient, whether they are pregnant and or using birth control pills and hormone replacement therapy, must be considered.
When estrogen levels are low, the body’s pain modulation system may be less effective. This can make pain more intense, especially during the second half of the menstrual cycle when estrogen levels are low and progesterone levels are high. Therefore, women with chronic pain may experience different pain levels during different phases of their menstrual cycle.
In addition, low levels of estrogen are present in postmenopausal women, potentially inducing pro-inflammatory effects within the TMJ, resulting in higher pain levels. And low levels of estrogen postmenopausal may potentiate temporomandibular joint degeneration.
When estrogen levels are high, however, the brain’s natural painkiller system releases endorphins and enkephalins to reduce pain signals. In addition, the inflammatory process is inhibited, and TMD-related pain decreases.
Studies have also found that all pain conditions throughout the body improve, and an individual’s pain sensitivity is lower when estrogen levels remain high. Estrogen levels are highest during pregnancy, with a resultant increase in natural pain relief.
Hormonal Influences on Ligaments
Regarding its influence on connective tissue, estrogen reduces the tensile strength of ligaments, predisposing them to increased joint mobility and injury risk. This makes TM joints and associated ligaments more susceptible to mechanical overload from behaviors such as awake and sleep bruxism, gum chewing, and nail and cuticle biting, leading to joint compromises and jaw dysfunction more commonly in women.
During pregnancy, increased levels of the hormone relaxin can exacerbate old TMJ joint clicking and locking problems, or prompt new symptoms. This inherent ligament laxity in women may, therefore, help explain gender disparities in TMJ problems.
As research continues on the impact of hormones on tissue biology and pain, I anticipate our knowledge will evolve and even possibly deviate from our current understanding.
Hormonal Influence on Muscles
Differences in muscle physiology between men and women may also contribute to variations in TMJ symptomatology and care-seeking behavior. Studies have shown that women’s jaw muscles fatigue more quickly when overworked, leading to rapid accumulation of lactic acid and resultant muscle pain and spasm. Women exhibit greater muscle flexibility and elasticity, potentially predisposing them to jaw hypermobility and associated joint problems. In contrast, men typically have more substantial muscle mass and thicker tendon attachments, which may protect against repetitive overuse forces.
Psychosocial Factors – Catastrophizing
Exploration of risk factors for persistent body pain has highlighted the significance of catastrophizing. Catastrophizing, or the cognitive process of magnifying the perceived threat of pain and its consequences, has been extensively studied. Women tend to catastrophize more about pain and, consequently, describe more intense and life-impacting pain. Long-term consequences of a pain problem are often feared by women, leading to emotional distress and anxiety.
The Brain’s Interpretation of Pain
Finally, gender differences in how the brain interprets pain impact prompts women to seek care for a TMJ problem. Brain imaging research has demonstrated that men and women have distinctly different patterns of brain activation in response to persistent pain. Furthermore, women tend to have lower pain thresholds and tolerance, prompting them to seek a diagnosis and initiate care more readily than men.
Conclusion
The higher prevalence of TMJ disorders among women is understandable from many perspectives. Therefore, it is often necessary to incorporate a broad array of multidisciplinary treatments to address both the physical and psychosocial elements that initiate and perpetuate temporomandibular problems.
I welcome your thoughts.
