Hi abauer!
Yes, Medicare's LCD for oral appliances for OSA specifies a 5 year replacement period. Here is the language from the LCD below:
"Oral appliances are eligible for replacement at the end of their 5-year reasonable useful lifetime (RUL). These items may be replaced prior to the end of the 5-year RUL in cases of loss, theft, or irreparable damage. Irreparable damage refers to a specific accident or to a natural disaster (e.g., fire, flood). Replacement due to wear-and-tear as the result of everyday use will be denied as statutorily non-covered prior to the expiration ofthe 5-year RUL."
Here is a link to the LCD:
https://med.noridianmedicare.com/documents/2230703/7218263/Oral+Appliances+for+Obstructive+Sleep+Apnea+LCD+and+PA/dc994aa8-c706-438b-9e31-db18a6be1358Other insurers generally do also specify their replacement period in their medical policies. Many have followed suit with Medicare at 5 years (i.e. Aetna). I have seen a few over the years that state 3 years instead.
Hope this helps!