Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2017-03-17, 10:24:23 | version 1.38.0
Fig. 4a Fig. 4b Fig. 4c Fig. 4d Figs. 4a–g (a) The center of the implant corresponds to the cingulum of the adjacent teeth. (b) Occlusal view of the final zirconia abutment. The distance A–B would be filled by the cervical contour of the final crown. (c) Frontal view of the final zirconia abutment. (d) The provisional restoration in place. (e) The definitive lithium disilicate crown with a cervical contour beyond the physiological parame- ters determined by the implant position associated with a vertical finishing line geometry. (f) One-year follow-up of the final crown showing signs of tissue reaction. (g) Radiograph of the definitive crown. Fig. 4e Fig. 4f The amount of this convexity is given by the value of the emergence angle (EA), which is defined as “the angle formed by the junction of a line through the long axis of the tooth, and a tangent drawn to the coronal of the tooth as it emerges from the sulcus”18, 19 (Fig. 3). The EA was recently measured on natural maxillary extracted teeth19 and it was found to have a mean value of 15°. In implant rehabilitation, the value of the EA and the convexity of the cervical contour are influenced by the bucco palatal position of the implant. The more palatal the implant placement, the greater the EA and cervical contour. Since the main task of the restorative dentist is always to make artificial crowns appear to be and function like a natural tooth, the artificially recreated angles and contours should be reproduced as closely as possible to nature. Changing the implant position according to the abutment shape For the past decade, the present authors have been working mainly with shoulder- less abutments (both for implants and natural teeth). In doing so, it has become apparent that implant placement following the conventional guidelines often results in the fabrication of crowns with subcrit- ical contours that difer greatly from those of a natural tooth. Figures 4a–g show an implant placed according to the conven- tional guidelines (i.e., at the cingulum of the future restoration) and restored using a shoulderless abutment. This resulted in a final restoration with an excessively con- vex EA that in the short term (one year) was already causing the surrounding soft tissue to react adversely. Article Advanced Implant Esthetics issue 2017 — 59 Fig. 4g