Question: Should I report 77334 for a head and neck cancer patient's mouth guard? South Dakota Subscriber Answer: Your payer will most likely consider 21089 (Unlisted maxillofacial prosthetic procedure) to be the correct code for this mouth guard fabrication. But generally an oral surgeon -- rather than a radiation practice -- will design, fabricate and bill for this device. Typically, oncologists order these mouth guards for patients with multiple metallic restorations, crowns or bridges to move the cheek and tongue away from the dental work to reduce backscatter burn. Payers take the "complex" part of complex treatment device code 77334 to heart. Reserve 77334 (Treatment devices, design and construction; complex [irregular blocks, special shields, compensators, wedges, molds or casts]) for devices requiring highly complex design to protect sensitive tissue, such as vital organs. And be sure the oncologist documents why this highly complex device is medically necessary.