Quantifying the Emergence Profile Contour for Immediate Provisionalization: A Proposed Mathematical Model

Figure 1. Established parameters in a healed ridge. Current implant guidelines suggest placement with a 3–4-mm vertical distance between the implant platform and future gingival margin, 2 mm of buccal bone thickness. In addition, there should be a 1.5-mm distance between an adjacent tooth and 3-mm distance between an adjacent implant. Figure 2. Established parameters in immediate placement. Implants placed in the extraction socket should provide for a gap of 2 mm between the implant platform and buccal plate, a vertical distance of 3–4 mm between the implant platform and existing free gingival margin, and 3–5 mm of apical bone for establishment of primary apical stability. Figure 3. Establishing a geometric model based on established parameters. The vertical depth is measured from a line corresponding to the height of the free gingival margin directly above the implant platform to the most buccal point on the implant platform (line a to b). The horizontal distance is measured from the buccal wall of the socket to the implant platform (line a to d). These lines make up the legs of a right triangle. Figure 4. Calculating the emergence line value. From the clinical situation, the established variables, vertical and horizontal distances, can be demonstrated as the legs of a right triangle. These can be used to calculate a value for the emergence line, as demonstrated from point B to point D. Figure 5. Quantifying degree of convexity. To better represent the actual shape of the emergence profile, it can be viewed geometrically as part of a circle. The degree of convexity over this distance can be changed by using circles of different sizes. A smaller circle represents a more contoured emergence profile with greater convexity. A larger circle represents a more gradual emergence profile with less convexity. Figure 6. Effect of prosthetic contour on emergence curve. To best correlate the clinical effect of altering the prosthetic contour on our model, we used circles with varying radiuses to reflect the process of over- and undercontouring. The smaller circle on the left represents the addition of prosthetic material to push soft tissue apically. The larger circle on the right represents removal of prosthetic material to encourage coronal migration of the soft tissue. Th indicates tissue height; PP, prosthetic platform.

Figure 7. Calculating the emergence curve value. Using the values obtained from the known clinical variables has given an established emergence line value. The degree of convexity of our prosthesis allows a value to be correlated to the radius of a circle. Using these variables, a value can be attributed to an emergence curve using known trigonometric relationships. Figure 8. Determining the emergence curve. Putting together each of our variables shows the relationship between the surgical location of our implant platform and the degree of convexity of our prosthesis and provides a value to our emergence curve. Figure 9. Tooth #8 extracted digitally using the free software meshmixer. Figure 10. Planning the implant placement using coDiagnostiX software following the criteria of vertical depth and the buccal gap. Figures 11 and 12. The design of the temporary after the software Straumann CARES Visual synergizes with coDiagnostiX, showing the submarginal contour and the buccal view. Figure 13. The digital design of the prosthetic model with the soft-tissue contour performed in the software Straumann CARES Visual.

Figure 14. The designed temporary printed and inserted with the appropriate implant abutment. Figure 15. Buccal view of the prosthetic printed model with the soft tissue. Figure 16. The fit of the printed temporary is verified on the model. Figure 17. The fit of the printed surgical guide is verified.