Management of a Large Mucous Retention Cyst at the Time of Sinus Floor Augmentations – A Case Report

FIGURE 1. Endodontic failure as sown on a PA of tooth 27 with severe tipping and pneumatization of the maxillary sinus between teeth 25 and 27.

FIGURE 2. Large mucous retention cyst occupying the left antrum (Panoramic film).

FIGURE 3A. Post-extraction radiograph demonstrating inadequate bone height for a dental implant in the edentulous space.

FIGURE 3B. & 3C. CT scan of demonstrating the extent of the mucous retention cyst in the left antrum.

Mucous retention cysts are often incidental findings when Cone Beam CT scans are done in preparation of the sinus lifts. They appear as rounded or dome-shaped opacities on the floor of the maxillary sinus. Most retention cysts either regress or show no significant change in size with time, therefore require no treatment; however, in the context of sinus floor augmentation, consideration must be given to their management. Small retention cysts can be left alone, provided that their displacement superiorly during the sinus floor augmentation will not block the maxillary sinus ostium. The maxillary ostium is an opening, connecting between maxillary sinuses and the nasal cavity. It is part of the ostiomeatal complex, providing drainage from the maxillary, frontal and eithmoidal sinuses into the middle meatus. Obstruction of any of these interconnected passages results in stagnation of secretion that may then become infected or perpetuate infection of the maxillary sinus. Alternatively, small to medium size retention cysts can be removed, leaving an opening in the Schneiderian membrane. Provided the cyst is not too large, the opening left behind can be sealed using a collagen membrane.

FIGURE 4. Pre-operative view of the edentulous site demonstrating facourable buccal-palatal ridge width.

FIGURE 5. Full thickness flap reflection exposing the lateral wall of the left maxillary sinus.

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