## 3 Results  
Boxplot diagrams of microstrains obtained from strain gauges bonded to vestibular and oral peri-implant sites of mini-implants in the mandibular models with one, two, three and four mini-implants, dependent on loading positions and loading forces, are presented in Figures 3-6. Figure 2: (**a–c**). Schematic drawing of loads applied to mandibular overdentures retained by one, two, three or four Ti–Zr mini-implants; (**a**). bilateral posterior OD loading in the model with four mini-implants; (**b**). unilateral posterior OD loading in the model with four mini-implants; (**c**). anterior (frontal) OD loading in the model with four mini-implants. Arithmetic means and standard deviations of microstrains obtained from strain gauges bonded to vestibular and oral peri-implant sites in the mandibular model with one MDI, dependent on the loading position and loading force, are presented in Figure 3 and Supplementary Table S1. Arithmetic means and standard deviations of microstrains obtained from peri-implant strain gauges bonded to vestibular and oral sites of MDIs in the mandibular model with two MDIs, dependent on the loading position and loading force, are presented in Figure 4 and Supplementary Table S2. Arithmetic means and standard deviations of microstrains obtained from peri-implant strain gauges bonded to vestibular and oral sites of MDIs in the mandibular model with three MDIs, dependent on the loading position and loading force, are presented in Figure 5 and Supplementary Table S3. Arithmetic means and standard deviations of microstrains obtained from peri-implant strain gauges bonded to vestibular and oral sites of MDIs in the mandibular model with four MDIs, dependent on the loading position and loading force, are presented in Figure 6 and Supplementary Table S4. When only one MDI was inserted in the midline, the highest peri-implant microstrains were recorded during anterior loading with 100 N forces from both vestibular and oral strain gauges. Posterior loadings with 150 N forces also elicited high peri-implant microstrains. The 2-factor MANOVA and Bonferroni post-hoc tests revealed that both loading forces and loading position had a significant effect on the amount of recorded peri-implant microstrains (\(p\) < 0.001, Supplementary Table S5a,..a.,a.b.). In the two-MDI model of the mandible, the highest microstrains were recorded from the vestibular and oral SGs of the MDI on the right side of the mandible under right-side unilateral OD loading with 150 N forces. Unilateral forces elicited the highest peri-implant microstrains in the right-side MDI, followed by the left-side MDI. The MANOVA and Bonferroni post-hoc tests revealed that both loading forces and loading positions elicited statistically significant effects on the amount of recorded peri-implant microstrains in the two-MDI model (\(p\) < 0.001, Supplementary Table S5b,..b.a.,b.b.). Figure 3: Boxplot diagrams of microstrains registered from strain gauges bonded to vestibular and oral peri-implant bones when only one mini-implant was inserted in the midline of the mandible. In the three-MDI model, the highest microstrains were recorded from the right posterior MDI under unilateral right side and bilateral loads, followed by the left MDI, while lower microstrains were recorded from the MDI inserted in the midline. The recorded microstrains were lower than in the one- and two-MDI models. The MANOVA showed significant effects of various loading forces and different loading positions on the amount of peri-implant microstrains in the three-MDI model (_p_ < 0.001, Supplementary Table S5c,c.a.,c.b.). In the four-MDI model, the highest microstrains were also recorded from the right-side posterior MDI during unilateral loading (on the right side) with the highest applied force (150 N). However, recorded microstrains were lower than in the one-, two- and even three-MDI models. Significant effects of loading positions and loading forces on peri-implant strains were shown by the MANOVA test (_p_ < 0.001, Supplementary Table S5d,d.a.,d.b.).