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19 CASE STUDY An important difference between the metal-reinforced model cast Maryland bridge described and zirconium bridges is in the esthetic effect of the enhanced light transmission of zirconium oxide. Because no dark gray clasp shell has to be masked, the light and shade effect is more similar to the natural tooth, espe- cially in the frontal upper jaw. Very high esthetic requirements apply, especially in temporary replacement of a single, mid- dle, upper front tooth (Fig. 14) . In the use of zirconium oxide Maryland bridges, the clasp elements are designed as shells, as with model cast Maryland bridges (Fig. 15) . The strategy of con- tinued processing in the mouth is also similar to that for metal bridges. The only difference is in the adhesive preparation of the natural tooth surface or of ceramic crowns. Here the conventional condition- ing is combined with a compomer (Re- lyX Unicem) to establish adhesion [9,10]. The vestibular clasp shells also have to be coated with an opaque front tooth com- posite (Fig. 16 and 17) . The patient case presented is of a pa- tient four weeks pregnant with a very high laugh line. Following an acute front tooth trauma, tooth 21 had to be ex- tracted. Implantation can be performed in one year at the earliest. The fabricat- ed zirconium oxide temporary has the potential of surviving this period of use without damage. Composite bridges milled using the CAD/ CAM technique represent another special case with the fixed Maryland bridges. The indication for these temporary bridges lies in the combination with a therapeutic change in bite (Fig. 18) . The significantly lower tensile strength compared with met- al or zirconium oxide leads to the necessity of a larger material cross-section. We have had good experience with this material used for extension bridges. A patient can be offered a fixed temporary restoration of this kind as an alternative to interim implants. For splint patients, the splint position can be adopted in this form of treatment and also checked and possibly changed within the wearing period. These composite bridges are secured with phosphate cement (Fig. 19 and 20) . Removal and reattachment In order that construction of a temporary works out in the implantological day- to-day routine, it very much depends on whether the surgical site can be accessed without great effort and also frequently. Similarly, the uncomplicated, multiple re- use of the same temporary without techni- cal backup from the dental lab is imperative. Given extensive courses of implantological therapy, temporaries sometimes have to be removed and reattached several times for augmentation, implantation, exposure etc. But especially the most possible loss- free removal of bonded model cast Mary- land bridges often leads to deformation of the clasp parts, to chipping of veneers or even to damage of the tooth surface (Fig 21) . Fig. 10: As a vestibular clasp shell was not used for the front tooth bridge for esthetic reasons... Fig. 11: ... the oral clasp shells were extended distally. Fig. 17: The vestibular clasp shells are also coated with an opaque front tooth composite. Fig. 12: Teeth 12 and 22 were extracted ... Fig. 16: To bond, the conventional conditioning is combined with a compomer.