<s>[INST] Hi. Im very concerned about my boyfriend. Evidently he had a root canal done poorly over a decade ago when he was young, and now its caused a cyst on the roof of his mouth. Hes getting the root canal redone tomorrow as well as a biopsy, but the doctor says that there is significant bone degradation in the area. Im scared. Could this be life-threatening? [/INST] Thanks for your query, I have gone through your query. The cyst is not life-threatening, but it has to be treated properly. Get the root canal treatment done followed bye nucleation of the cyst. Then send the biopsy to histopathological examination to rule out from other lesions like benign tumors. If there is severe bone loss we can try placing bone like material(graft) after nucleation of the cyst and support the tooth. If there is no possibility of placing the graft and if tooth is mobile then it has to be removed. Consult a good oral maxillofacial surgeon and get it done hope my answer will help you, take care. </s>