What is the fine-grained topic of the following text: Custom-made oral appliances are recommended as a first line of treatment for mild to moderate obstructive sleep apnea, and are recommended as “better than no treatment at all” for severe sleep apnea in cases where the patient cannot or will not use the CPAP machine. Only return the topic.
Use of Custom-Made Oral Appliances in Treating Obstructive Sleep Apnea