Ultrastructural observations of peri-implant mucosa morphology around different types of abutment in humans

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the morphological aspects of peri-implant mucosa around abutments of differing geometry (biconical and cylindrical) and of differing surface micromorphology. The samples were taken from seven patients who had undergone implant surgery at least one year prior to the study. In samples from biconical abutments, SEM of the sulcular epithelium showed that it consisted of flattened polygonal cells with a surface resembling a honeycomb. Superficial desquamation was rarely found. In contrast, in the samples from cylindrical abutments, the sulcular epithelium showed extensive desquamation and surface irregularity, but not the honeycomb structure in its superficial cells. TEM showed in both abutment types a morphologically normal epithelium, with a normal maturation cell pattern. Desquamation of the more superficial layers of the epithelium, associated with thinning in the superficial layer of flattened cells, was more evident around cylindrical abutments. In the transitional area between the sulcular and junctional epithelium, an intra-epithelial leukocyte infiltrate, and a larger amount of keratohyalin granules in the more superficial cells was observed. The morphological differences in peri-implant mucosa between the two abutment types may be related to differences in morphology of the metal surfaces of the abutments themselves.