Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities.

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Dental Implant Systems

The machinability of cast titanium and Ti-6Al-4V.

Experimental Ti-Ag alloys (5, 10, and 20mass% Ag) and Ti-Cu alloys (2, 5, and 10mass% Cu) were cast into magnesia molds using a dental casting machine, and their grindability was investigated. At the lowest grinding speed (500m⋅min-1), there were no statistical differences among the grindability values of the titanium and titanium alloys. The grindability of the alloys increased as the grinding speed increased. At the highest grinding speed (1500m⋅min-1), the grindability of the 20% Ag, 5% Cu, and 10% Cu alloys was significantly higher than that of titanium. It was found that alloying with silver or copper improved the grindability of titanium, particularly at a high speed. It appeared that the decrease in elongation caused by the precipitation of small amounts of intermetallic compounds primarily contributed to the favorable grindability of the experimental alloys.

https://www.jstage.jst.go.jp/article/dmj1982/22/2/22_2_191/_pdf

Grindability of dental cast Ti-Ag and Ti-Cu alloys.

Abstract Metal and oxide surface reactions formed by heating in the spectrometer at 300–400° at a vacuum of ca. 10 −9 Torr (oil diffusion pumps) were studied. As a result of spectral observations before and after heating, the metals studied were classified into five groups. In the first group, oxide films on the metal surface are easily evaporated because of the high vapour pressure of oxide; in the second, the oxide films are easily reduced in the spectrometer; in the third, the oxide film formed on the metal is reduced but the bulk oxide is not easily reduced; in the fourth, very stable oxide films are formed and the bulk oxide is also stable; and finally in the fifth, the oxide film formed on the metal is apparently reduced, yet the bulk oxide is very stable.

On the Surface Chemical Reactions of Metal and Oxide XPS Samples at 300-400°at a High Vacuum Produced by Oil Diffusion Pumps(Chemistry)

Cutting efficiency of air-turbine burs on cast titanium and dental casting alloys

Indium oxide films formed on the surface of silica glass samples by selective oxidation have been shown to greatly improve the adherence of gold-indium alloy to the silica glass. In order to clarify the role that the oxide films play in the reaction, thin indium films have been evaporated onto silica glass and heated at temperatures of between 973 and 1473 K, both in air and in hydrogen gas. Electron spectroscopy for chemical analysis (ESCA) measurements have then been made to investigate the chemical environments around oxygen and indium atoms at the reacting interface between the oxide and glass. Measured 01s and In3d5/2 spectra reveal the formation of non-bridging oxygen atoms at the interface, in addition to the original bridging oxygen atoms in silica glass. Introduction of the non-bridging oxygen atoms and indium ions into the silica glass is concluded to be an essential factor in promoting good adherence between the gold alloy and silica glass.

ESCA study on the mechanism of adherence of metal to silica glass

Cast titanium was ground with commercial vitrified wheels made of alumina abrasives, and their grinding performance was investigated. For cutting, the appropriate circumferential speed of the alumina wheels was about 700 m/min. A speed lower or higher than this yielded unfavorable grinding results, which were attributed to wheel loading or chemical attrition of the abrasive, respectively. The hard wheel made of the A abrasive was suitable for grinding of titanium, and moreover, the wheel of the WA abrasive was more suitable than that made of the A abrasive. Generally, the cutting rate of the alumina wheels was inferior to that of the silicon carbide ones investigated previously. Depression of the wheel against the work yielded unfavorable grinding results; the manner in which the wheel was moved over the work during grinding was very important, compared with the silicon carbide wheels. Although the wheel was moved over the work, the high circumferential speed of the wheel resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn. The grinding burn layer mainly consisted of a few microns-thick titanium oxide.

Grinding of titanium. 2. Commercial vitrified wheels made of alumina abrasives

Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated.

Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives

The tracer element molten (TEM) method has been developed for flow visualization of molten Titanium in dental precision casting. The principle of this technique is as follows. When Titanium is cast, the tracer element wire inserted previously into the selective point of the sprue is molten little by little and distributed according to the molten Titanium flow in the mold cavity. After solidification, to observe the flow pattern, the tracer element needs to be analyzed on a section of the casting by EPMA equipped with the stage scan mapping system. This technique using Ag, Au, Pd or Pt as a tracer has been applied to some simple castings in shape and has been confirmed to be a very powerful technique for Titanium flow visualization in dental castings.

Determination of titanium flow by the tracer element molten method in the dental precision casting. 1. The principle of flow visualization and application to simple castings

Shiokawa N

Papers

ESCA study on the mechanism of adherence of metal to silica glass

Grinding of titanium. 2. Commercial vitrified wheels made of alumina abrasives

Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives

Determination of titanium flow by the tracer element molten method in the dental precision casting. 1. The principle of flow visualization and application to simple castings

Study on Grinding of Base Metals Alloys(2)