36 osteotomies performed between 1982 and 1988 involved opening the maxilla. Postoperative clinical, radiographic and endoscopic follow-up revealed that the majority of the patients had no or only minor pathological alterations of the maxillary sinuses. Sinuscopy showed only 2 maxillary sinuses to have more extensive mucosal alterations. Remarkably, it was particularly the osteosynthesis material protruding into the maxillary sinus that was surrounded by or overgrown with non-irritated mucosa.