There are known relationships between sleep disordered breathing, TMJ damage/dysfunction and clenching or grinding. In the dental industry, clenching and grinding is known as bruxing or bruxism.
Because there are varying predispositions to bruxism and inconsistencies in the characteristics of subjects studied, the topic has been controversial in medical and dental journals in the past.
What we do know for sure from studying sleep apnea is when you clench or brux, the jaw muscles contract and therefore open the airway. Your body’s way of getting the air it needs. Just like pulling your hand away from something hot or your eyes blinking to protect them, the body instinctively knows what to do to survive. So, when suffering from sleep breathing disorders (sleep apnea), your body will clench or brux to open the airway.
When sleep apnea is successfully treated with an orthopedic orthotic (oral appliance), the clenching or bruxing subsides and has even been known to reach complete resolution. Likewise, a damaged or misaligned TMJ can contribute to clenching or grinding.
A dental nightguard is not the same as an orthopedic TMJ appliance. It has a different design and mechanical force on the TMJ. Dental nightguards sometimes lessen clenching or grinding, but more often exacerbate it. Although you may be protecting your teeth from each other, you may be causing further TMJ damage.
If you find you are clenching or grinding harder with your dental nightguard that would strongly suggest an underlying sleep breathing problem or TMJ damage that is being exacerbated.
If your current appliance is causing more problems or simply not working, consider having a TMJ specialist evaluate the jaw joints, airway, and the design of your dental appliance to assess if it might be contributing to increased joint pressure or airway constriction.