blood loss. After the operation, the patient should be transferred to the intensive care unit.

15.3  New Developments

15.3.1  Titanium Selective Laser Melting

(Ti-SLM)

Direction of movement

Melting bath

Titanium powder

Melted material

Since the mid 1990s allogenic implants were applied to restore skeletal defects in the cranio-maxillofacial region with varying success. Due to incorrect planning, manufacturing, or application, these implants found limited acceptance.

Today, the higher life expectancy and mobility of patients, as well as an increasing number of younger patientsinneedofsuchimplants,requirebettersolutions than in the past. The highly sophisticated data acquisition and better computer programs have improved the precision and acceptance of the implants.

An improved integration of titanium implants at the titanium-bone interface could be realized by inducing better bone ingrowths by producing a more porous surface structure. The positive effects of increasing the surface area are well known from dental implants (Hattar et al. 2005; Klein et al. 1994; Li et al. 2005). The manufacture of implants with graded mechanical properties concerning reduced weight, full freedom of form and stiffness is not possible with the current state-of-the-art technology.

15.3 1.1  The SLM process

By SLM it has become possible to produce complex, three-dimensional titanium implants directly out of serial materials. Titanium powder is brought onto a work platform in layers of 0.03-0.1 mm thickness. According to three-dimensional computer data sets, a layered implant construction is possible. A focused laser beam of high intensity delivers the energy to melt the powder particles to form a solid titanium implant (Hon and Gill 2003) (Figs. 15.7a, b and 15.8).

Implants manufactured according to the SLM process yield densities of approximately 100% without postprocessing steps. Postprocessing procedures, however, are necessary to stabilize titanium molecules of

b

Laser beams

Fig. 15.7  (a) Manufacture of SLM implants: melting titanium powder. (b) Manufacture of SLM implants: layered technique

Fig. 15.8  SLM manufacture of a cranial implant with hollow and grid structures

the outer layers to prevent them from dissolving after implantation.

Acidic dipping followed by heating stabilizes the molecular structure of the implant. The characteristic of titanium enables its design and manufacture in complex three-dimensional forms. The main advantages of the SLM process are:

•Manufacture of complex geometries

•Direct rapid production of customized geometries