Primary vs Secondary Sleep Related Bruxism
It has been postulated that SRB occurs only with obstructive sleep events and acts to wake the patient to restart normal breathing. This however does not explain the vast number of patients with SRB who do not demonstrate sleep disordered breathing. It is more productive to describe SRB as primary, or occurring independently, and secondary, occurring concurrently with other disorders.
Primary Sleep Related Bruxism
As discussed, this form occurs independently of sleep disordered breathing (OSA). It affects men and women equally. On a sleep tracing, it is distinguished by the lack of obstructive events.
In figure 1, a tracing of primary SRB, it is defined by erratic but undisturbed breathing. This is a classical presentation of primary SRB.
Secondary Sleep Related Bruxism
In figure 2, the SRB events occur just before and/or after a sleep disordered breathing event. This is classical secondary SRB. The obstructive apnea event is marked in green. The sleep-related bruxism is the upper tracing and occurs just before and/or after the breathing event.
Another secondary form of SRB is secondary to SSRI or SSNRI medications. This appears as classical primary SRB, with disturbed but consistent breathing occurring.