Mucosal Adhesion Phenomenon After Maxillary Sinus Floor Elevation

Objectives: To describe the histological events that occur after maxillary sinus floor elevation when elevated and pristine sinus mucosa come in close proximity or in contact with each other.
Methods: A retrospective analysis of one-hundred and fifty-two elevated sinuses in seventy-six rabbits were histologically analyzed. Sites without adhesions were classified as having No Proximity, whereas the adhesion stage was subdivided into the Proximity, Fusion, and Synechia stages. The widths of the pseudostratified columnar epithelium and the distances between the two layers were measured and analyzed at various standardized positions.
Results: Thirty-one sites presenting adhesions were found. Twelve sites were Proximity stage, presenting cilia of the two epithelial layers that were shortened and interlinked within a mucous context. Hyperactivity of globet cells was also observed. In other cases, the hypermitotic epithelium attempted to reach the opposite mucosa. The 15 fusion stage sites presented regions with epithelial cells in the two mucosal layers that interpenetrated each other. Four sites presented synechiae, represented by bridges of connective tissue connecting the two lamina propria
Conclusions: A close proximity or tight contact between the elevated and pristine mucosa still adhered to the bone walls might occur after maxillary sinus floor elevation inducing hypermitosis of the epithelial cells, and adhesion of the two layers until their disappearance, resulting in synechiae.