Implant Surfaces and their Biological and Clinical Impact by Ann Wennerberg Tomas Albrektsson & Ryo Jimbo

Author:Ann Wennerberg, Tomas Albrektsson & Ryo Jimbo
Language: eng
Format: epub
Publisher: Springer Berlin Heidelberg, Berlin, Heidelberg

Many researchers studied the SLA surface commercially produced by Institut Straumann AG, Basel, Switzerland, and found that the Sa value (the arithmetic mean of deviations in the roughness profile from mean line in 3 dimensions) is 1.79 ± 0.2 μm (evaluated at the top of the thread) [18] and the Ra value (the mean height of the roughness based on only 2 dimensions) is 2.93 ± 0.46 μm [19]. Additionally, the difference between the Sa and Ra value with regard to these 2 studies can be related to the fact that the Sa value was measured by optical profilometry [18] while the Ra value was determined by evaluating scanning electron micrographs from implants using image analysis software [19]. Such a titanium oxide surface exhibits low surface energy because of adsorbed hydrocarbons and carbonates from ambient air [2]. Taborelli et al. confirmed the water contact angle of the SLA surface about 117° ± 2.7 [20], while Buser et al. measured the dynamic contact angle (DCA) of the SLA surface and the results indicated that the SLA surface was hydrophobic (DCA = 138.3° ± 4.2) [11]. During acid-etching, the titanium oxide layer is dissolved, and small native hydrogen ions diffuse into the unprotected implant surface, which enrich the implant surface with hydrogen and precipitate into titanium hydride (TiH) [21]. X-ray diffraction (XRD) analysis of SLA-treated titanium samples showed the presence of 20–40 % of titanium hydride (d-TiH2-x) in addition to titanium [22, 23].

It has been reported that the etching process modifies the titanium surface composition of SLA-treated implants. Observation has shown that the dull SLA surface is soft [24], particularly when compared with a titanium plasma–sprayed (TPS) surface. The SLA surface consists mainly of TiO2 with some carbon containing contamination (like hydrocarbons) due to the exposure to air. X-ray photoelectron spectroscopy (XPS) analysis indicated that the SLA surface had a 44.2 ± 1.9 at% (atomic concentration) oxygen (O) concentration, an 18.4 ± 1.6 at% titanium (Ti) concentrations [11], and a 37.3 ± 3.4 at% carbon (C) concentration, which is comparable to the result of Kang et al. with 47.1 at% O, 20.1 at% Ti, and 32.0 % C [25].

Besides pure titanium, SLA surfaces can also be produced on other materials, such as titanium-zirconium alloys [13] and zirconium dioxide ceramics (Fig. 9.2). Due to the similar crystal structure of titanium and zirconium, the TiZr alloy can be sandblasted and acid-etched, exactly like commercially pure titanium (compare 3.1 in this chapter), to create a micro-rough SLA surface (Fig. 9.3). In contrast to that, with regard to zirconia ceramics, it has been shown that surface treatment procedures that create micro-rough surface topographies, like conventional sandblasting or uncontrolled machining processes, might reduce the fracture strength of zirconia dental implants and lead to implant fractures [26, 27]. Thus, the manufacturing processes of creating micro-rough surfaces on commercially pure titanium or titanium alloy implants cannot simply be transferred to zirconia but must accurately be attuned to the material properties of the zirconia ceramics. The first manufacturing process that created a micro-rough surface topography on zirconia implants that was similar to the SLA surface on

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