Purpose: To determine the range of vertical cantilever (VC), real cantilever (RC), and height of the imaginary triangle (h) formed by the bases of the three implant cylinders in full-arch mandibular prostheses supported by three implants. Materials and Methods: The sample comprised 203 patients (147 women, 56 men; mean age, 58 years, range, 37 to 79 years) with full-arch mandibular rehabilitations. Their prostheses were measured in relation to implant placement to characterize numerical values for VC, force arm of the lever system (represented by the distal cantilever or RC), and resistance arm of the system (represented by the height of the imaginary triangle formed by the bases of the three implants). Data were tabulated and means and standard deviations calculated for all measurements. The range of each of the three measurements was then divided into quintiles for characterizing data distribution. Results: The mean (standard deviation) values found were as follows: VC1 = 17.11 (3.39) mm; VC2 = 17.46 (2.89) mm; VC3 = 16.68 (3.16) mm; RC1 = 14.67 (3.90) mm; RC3 = 15.02 (4.15) mm; h = 8.27 (2.96) mm. Conclusion: VC ranged from 7.37 to 26.44 mm, RC ranged from 4.00 to 26.93 mm, and the height of the imaginary triangle formed by the bases of the three implant cylinders ranged from 0.37 to 15.33 mm. Keywords: biomechanics, Brånemark protocol, dental implants, dental prosthesis, implant-supported, mandibular prosthesis