CDEN0210

16 I I special _ implants _In the clinic The chairside process is simplified by the use of this acrylic resin guiding device that provides a visual aid for the appropriate position for drilling the access holes. Ideally, porcelain should be removed using a diamond high-speed bur with copious irrigation. I prefer to use a round diamond bur for this purpose, as it is less likely to cause porcelain chipping. If the prosthesis is metal ceramic, the metal substructure is first penetrated with a small round carbide bur. Sub- sequently, a metal-cutting tungsten carbide bur is used to widen the access as required. Figure 10 shows a screwdriver passing through the guide into the abutment screw. Figures 11a and b show the precision of the preparation without over- preparation. Once the access hole has been debrided of obturating materials, an appropriate screwdriver is inserted. In order to prevent ceramic delami- nation, it is important to ensure the driver is not contacting any porcelain before significant torque is applied. I initially insert the driver and inspect for lack of contact with the porcelain. Following, I apply light hand torque to the driver in order to determine that it is fully seated before asecondinspectiontoensurenoporcelaincontact. Finally, the screw and the prosthesis are removed. cosmeticdentistry 2_2010 Fig. 10Fig. 9 Fig. 8bFig. 8a Fig. 11bFig. 11a