Histologic Analysis of the Oral Mucosa Lining Osseointegrated Implant Cover Screws: A Study in Humans
Osseointegrated dental implants are inserted into the alveolar ridge, and for them to function as tooth replacements, the surrounding tissues need to adapt to them. Just as with teeth, dental implants traverse the oral mucosa and have access to the contaminated environment of the oral cavity. Therefore, periodontal and peri-implant tissues are important for establishing a protective barrier. The aim of the present study was to perform a histologic analysis of the mucosa surrounding osseointegrated implant cover screws. For this study, 17 mucosal specimens were obtained from 12 patients during the second surgical session for implant exposure to the oral environment. After histologic preparation, specimens were sectioned perpendicularly to the mucosal surface to a thickness of about 3 µm, stained with 1% toluidine blue, and examined under light microscopy. All specimens showed a keratinized, stratified, squamous epithelium with well-defined strata. In the lamina propria, unorganized dense connective tissue was noted in the reticular layer, and in 4 samples, a chronic inflammatory infiltrate was seen in this region. The papillary layer presented tall connective papillae consisting of loose connective tissue. The results of this study confirm the hypothesis that the mucosa that conceals osseointegrated implant cover screws has the same morphologic characteristics as the alveolar masticatory mucosa. Furthermore, clinical conditions of normality in peri-implant tissues may not coincide with situations of histologic normality.Abstract
Figure 1. Radiograph of Branemark-type implant with length of 15 mm and diameter of 3.75 mm. Figure 2. Oral mucosa covering Branemark-type implant before second surgical session, that had healed clinically isolated from the oral cavity. Figure 3. Circular scalpel in area with strip of remaining inserted gingiva approximately 4 mm wide. Figure 4. Sample of oral mucosa (epithelial surface). Figure 5. Sample of oral mucosa (connective surface).
Figure 6. Photomicrograph of epithelium-connective interface (ECI), showing the presence of mastocytes in the basal layer of the epithelium (arrow) (toluidine blue, original magnification ×32). In B, details of a mastocyte in the basal layer can be seen (arrow). Figure 7. Photomicrograph of the oral mucosa showing the stratified, squamous, keratinized epithelium (arrow) with well-defined strata. Basal layer (BL), spinous layer (SL), granulous layer (GL), and corneal layer (CL) (toluidine blue, original magnification ×40). Figure 8. Photomicrograph of the oral mucosa showing epithelial ridges (ER) of stratified, squamous, parakeratinized epithelium (arrows) and connective papillae (CP) made up of loose connective tissue (toluidine blue, original magnification ×32). Figure 9. Photomicrograph of the oral mucosa showing fibers and cells in the reticular layer. Fibroblasts (F), mastocytes (M), and collagen fibers (CF) (toluidine blue, original magnification ×50). Figure 10. Photomicrograph of the oral mucosa showing the presence of metachromatic material in the reticular layer (arrows) amid collagen fibers (CF) (toluidine blue, original magnification ×32). Figure 11. Photomicrograph of the oral mucosa showing the presence of chronic inflammatory infiltrate in the reticular layer (arrows) with increased microcirculation (m) (toluidine blue, original magnification ×32).
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