Are mucous retention cysts and pseudocysts in the maxillary sinus a risk factor for dental implants? A systematic review

BACKGROUND: Mucous retention cysts and pseudocysts of the maxillary sinus are benign lesions present in up to 13% of adult patients. Different surgical approaches for sinus lift and dental implant placement in the presence of these lesions have been proposed. MATERIAL AND METHODS: A systematic review was performed following the PRISMA statement recommendations to answer the PICO question: Does the aspiration or removal of mucous retention cysts/pseudocysts before or during sinus lifting and dental implant placing, affect the survival of the implants? The study was pre-registered in PROSPERO (CRD42020185528). Included articles quality was assessed using the “NIH quality assessment tool” and “The Newcastle-Ottawa scale”. RESULTS: Previous literature in this field is scarce and with a low level of evidence. There are no randomized prospective studies. Only 19 studies were identified, being composed of 2 cohort studies and 17 case series/reports. These studies involved 182 patients with a previous history of mucous retention cyst or pseudocyst in 195 maxillary sinuses where 233 implants were placed. The mean age of the patients was 45.5 (range: 12-80 years); 122 (67%) were male patients and 60 (33%) were female patients. The mean follow-up of the patients was 17.6 (range: 4-90 months). Only two fail was reported. No differences were identified in relation to the surgical approach or in relation to the removal/aspiration of the sinus lesion (prior to or simultaneous to sinus grafting) or not. CONCLUSIONS: The level of evidence was grade 4 according to the CEBM and further studies are needed to confirm this observations, but with the available data, dental implants placement after sinus lift procedure in patients with mucous retention cysts and pseudocysts seems to be safe and present high survival regardless on the removal of the lesion or not. Key words:Dental implants, maxillary sinus, sinus lift, mucous retention cyst, pseudocyst.