## 3 Results  
To showcase the use of a teeth-supported type of sleeveless guide during the surgical procedures for implant bed preparation and dental implant insertion, a simulation of the procedure is displayed in Figure 6. For example, for the insertion of a \(\O4\) mm diameter and 10 mm length AnyRidge(tm) (MegaGen, Daegu, Republic of Korea) dental implant, the following guide stop drill sequence is recommended: 2 mm \(\times\) 7 mm, 2 mm \(\times\) 8.5 mm, 2 mm \(\times\) 10 mm; 2.5 mm \(\times\) 10 mm; 2.8 mm \(\times\) 10 mm; 3.3 mm \(\times\) 10 mm; and 3.8 mm \(\times\) 10 mm. The drilling protocol is adjusted according to the crestal bone density to increase the implant's primary stability [8]. Figure 6: Representative digital images suggestive of flapless implant bed preparation and insertion with the aid of the surgical guide, without metallic sleeves: (**a**) the guide is placed over the remaining natural teeth (tooth-supported guide type); (**b**) an initial drill is needed to initial the path in the cortical bone; (**c**) the implant osteotomy has to be prepared using the guide stop drills in a successive order based on drill diameter and length; (**d**) guided dental implant insertion. The.stl file of a tooth-supported mandibular surgical guide, designed in R2 Ware software and reduced, optimized, and cleaned in the open-source software MeshLab, was used for FEA in CATIA v5 software. The quality of the finite elements and the overall analyzed guide was very good (99.98%), meaning that the solid 3D model obtained from the designed guide was correct and consistent. This value was obtained by using a CATIA v5 program tool called Quality Analysis. The Quality Analysis dialog box appears with a default list of criteria that are taken into account for the mesh quality check and for the mesh optimization. Figure 7 presents the discretization of the guide's model, revealing that its mesh is very complex. The FEA was also a complex one: the program identified and took over 435,711 degrees of freedom (DOF). In the present study, the use of the first drill (O2 mm diameter) \(\times\) 10 mm length was simulated for implant bed preparation in the mandibular bone. Von Mises stresses, determining whether the material and the design of the surgical guide will lead to guide fracture, were determined. As is obvious, the most stressed area is on the cylindrical surface of the main hole of the guide, through which the drill passes. Since the moment due to the friction between the drill shank and the guide is very small (10% of Mw), its influence is not so important. The axial force is the one that, at a given moment, loads the tapered area present at the entrance to the main hole of the guide and produces a maximum stress of 6.92 MPa (Figure 7a). This stress value is not low but normal, considering that the flexural strength of the guide's material is approximately 80-86 MPa. As a consequence, the first remark is that there is no danger of the guide failing/breaking, provided that it has no manufacturing defects and is correctly fixed on the teeth so that it does not vibrate in the drilling process. Figure 7: Results of the finite element analysis: (**a**) location and values of the maximum stress; (**b**) displacements of the guide and their maximum value; (**c,d**) propagation of the displacements show–ing the most critical areas. The areas with maximum stresses appear on the guide in the special built-in window meant to allow cooling during the drilling process and good visualization for correct implant positioning. This happens because the tapered and cylindrical surfaces are partially interrupted, and there are also sharp edges, which are concentrators of forces and stresses. The area of maximum stress is red (Figure 7a), then, as the stress decreases, the areas are orange, yellow, green, up to dark blue, which are the least stressed. Figure 7b shows the displacements of the guide as red, orange, and yellow areas, but their maximum value is 0.002 mm.