Titanium Dental Implant Surface Micromorphology Optimization
The purpose of this investigation was to create an acid-etched implant surface that is similar to that created by sandblasting combined with acid etching and to compare it with the surfaces of various commercially available screw-type implants. Titanium grade 5 disks were machined in preparation for acid etching. Tests were carried out using different acids and combinations of them with varying time exposures. All etched surfaces were scanned with an electron microscope, and digital images were created for visual evaluation and description of the surfaces. The etched surfaces were evaluated for surface morphology (combination of microroughness and waviness); the surface most like the sandblasted/acid-etched surface was best obtained with a combination of sulfuric and hydrochloric acids. The etched titanium disks were fixed in acrylic resin (2 were cut and polished and 2 were scored and fractured) and the surface profile was examined. In the second part of the investigation, 28 screw-shaped implants that were manufactured from commercially available titanium grade 5 were selected and divided into 2 groups: 3 implants were used as controls (machined surface), and 25 implants were processed using the preferred etching method determined in the first part of the investigation. Magnifications of 27, 200, and 2000 were used to analyze the first 2 consecutive crests of threads, flanks, and root of threads of each implant with the treated surface. A 3-dimensional optical interferometer was used to characterize the surface roughness of both control and test groups. Three screws were selected from each group and measured at 9 sites: 3 measurements each on the crest, root, and flank of the threads. To describe the surface roughness in numbers, the following parameters were used: the average height deviation (Sa), the developed interfacial area ratio (Sdr), the fastest decay autocorrelation length (Sal), and the density of summits (Sds). In addition, in a third experiment, the surfaces of 5 commercially available screw-type implants and the experimental ones were analyzed and compared. It was concluded that the new experimental acid-etched titanium surface had the features of a roughened titanium surface, with glossily microroughness and large waviness. In general, the experimental surface was significantly rougher than the selected commercially available implants and similar to a sandblasted/acid-etched surface (top Sa: 2.08 ± 0.36 μm, Sdr: 1.34 ± 0.3 μm, valleys: 1.16 ± 0.1 μm and 0.68 ± 0.1 μm, flanks: 2.24 ± 0.8 μm and 1.27 ± 0.1 μm, respectively).Abstract
Images of electron microscopic scans of titanium disks. (a) Disk with machined surface. Regular machining grooves are apparent on the surface (magnification ×2000). (b) Disk with hydrochloric acid–etched surface shows a poor microtexture without micropits. (c) Disk with hydrochloric/sulfuric acid–etched surface displays a poor microtexture with few micropits and smooth waviness. (d) Disk with surface etched by sulfuric/hydrochloric acids and phosphoric acid. Surface waviness is clearly expressed without microtexture. (e) Disk with surface etched by sulfuric and hydrochloric acid shows micropits of 1 to 10 μm, large valleys of 20 to 30 μm, and peaks of different size.
and 3. Figure 2. Electron microscopic images of titanium disk profiles. Significant roughness is seen in both profiles. (a) Cut and polished surface. (b) Cut and broken surface. Figure 3. Measurements from digital topographic images. (a) Machined surface with clear direction of the surface topography. (b) Sulfuric/hydrochloric acid–etched surface; significant peaks and valleys are distributed regularly.
and 5. Images of electron microscopic scans of experimental titanium implants. Figure 4. (a) Implant with machined surface (magnification ×27). A clear direction of grooves and ridges remains from the machining process. (b) Top of machined thread with irregular deep grooves and ridges (magnification ×2000). (c) Machined thread with less distinct ridges and grooves (magnification ×2000). (d) Valley and flank of machined thread with distinctive ridges and grooves (magnification ×2000). Figure 5. (a) Implant with acid-etched surface (magnification ×27). Regular distribution of surface texture. (b) Top of acid-etched thread with micropits of 1 to 10 μm, large elements of approximately 30 μm, and peaks of different size (magnification ×2000). (c) Acid-etched valley with micropits of 1 to 20 μm and small peaks (magnification ×2000). (d) Acid-etched flank with clearly expressed micropits of 1 to 10 μm, large elements of approximately 30 μm, and peaks of different size (magnification ×2000).
Contributor Notes
Gintaras Juodzbalys, DMS, PhD, is associate professor in the Department of Maxillofacial Surgery, and Marija Sapragoniene, DMS, PhD, is associate professor in the Department of Analytic and Toxicological Chemistry, Kaunas University of Medicine, Kaunas, Lithuania. Address correspondence to Dr Juodzbalys, Vainikų 12, LT-46383 Kaunas, Lithuania (gintaras@stilusoptimus.lt).
Ann Wennerberg, DDS, PhD, is professor in the Department of Biomaterials and Handicap Research and the Department of Prosthetic Dentistry, Dental Material Science, Göteborg University, Göteborg, Sweden.
Tomas Baltrukonis, DTS, is at the Dental Implant Centre “Stilus optimus” Kaunas, Lithuania.