A long-held belief by many patients and dentists is that jaw problems are caused by tooth-grinding (bruxism) during sleep. According to the 2020 NAM report (page 3-20), “sleep bruxism has also been linked with TMJ [disorders] in some studies; however, recent meta-analyses describe the evidence linking sleep bruxism and TMD pain as inconclusive (Jimenez-Silva et al., 2017; Baad-Hansen et al., 2019).” Other investigators (Lund, Raphael) have shown that the linkage between sleep bruxism and jaw pain problems is relatively minimal.
It has been shown that the oral activities of sleep bruxism are part of the normal sleep cycle. While almost everyone bruxes during sleep, if you do it excessively, it can be legitimately labelled as true sleep bruxism. This is measured in a sleep lab.
There are no preventive treatments for sleep bruxism, so the only treatment that may be helpful is wearing a plastic nightguard – mainly to protect the teeth from excessive wear.