Purpose: A diagnostic wax try-in has been recommended to correctly design the future prosthesis for edentulous maxillae and to predict its effect on the supporting oral tissues. The objectives of this study were to analyze (1) the reliability of this diagnostic tool in planning fixed implant-supported prostheses and (2) the amount of prosthetic compensation required. Materials and Methods: Nine female patients participated in this prospective study (mean age, 53.6 years). After anamnesis, clinical examination, and preoperative analysis, the patients underwent preoperative prosthetic preparation, and the wax try-in was fabricated. To evaluate the efficiency of the diagnostic wax try-in, three profile cephalograms were taken of each patient: (1) with the initial conventional prosthesis, (2) with the wax try-in, and (3) with the implant-supported prosthesis. Two analyses were carried out for the assessment of lip support: the nasolabial angle and Steiner's S-line. To analyze the amount of prosthetic compensation, two measurements-vertical and horizontal distances- were obtained for each wax try-in and final prosthesis. Results: For the Steiner's S-line, the results of the statistical tests indicated no significant difference between the initial and final prosthesis for the upper (P = .237) and lower lips (P = .237), and between the wax try-in and final prosthesis for the upper (P = .463) and lower lips (P = .463). Regarding the nasolabial angle, the results of the statistical tests indicated no significant difference between the initial and final prosthesis (P = .594), and between the wax try-in and final prosthesis (P = .800). Regarding prosthetic compensation, the results of the statistical test indicated no significant difference between the vertical (P = .753) and horizontal evaluations (P = .855) carried out for the wax try-in and those for the final prosthesis. Conclusion: On the basis of the data collected, it was concluded that the methods of replacing muco-supported prostheses with implant-supported fixed prostheses were efficient at maintaining the original lip design. The wax try-in was capable of predicting the future lip design and the prosthetic compensation of the final prosthesis. More studies are required to consolidate these data. Schlagwörter: dental implants, fixed dental prosthesis, oral rehabilitation, prosthetic planning, total prosthesis