Mandibular Flexure and Peri-Implant Bone Stress Distribution on an Implant-Supported Fixed Full-Arch Mandibular Prosthesis: 3D Finite Element Analysis

Abstract

Purpose: The purpose of this study was to evaluate and compare the effect of three mandibular full-arch superstructures on the peri-implant bone stress distribution during mandibular flexure caused by mid-opening (27 mm) and protrusion mandibular movements.

Materials and methods: Three-dimensional finite element models were created simulating six osseointegrated implants in the jawbone. One model simulated a 1-piece framework and the other simulated 2-piece and 3-piece frameworks. Muscle forces with definite direction and magnitude were exerted over areas of attachment to simulate multiple force vectors of masticatory muscles during mandibular protrusion and opening.

Results: During the movement of 27.5 mm jaw opening, the 1-piece and 3-piece superstructures showed the lowest values of bone stress around the mesial implants, gradually increasing towards the distal position. During the protrusion movement, bone stress increased compared to opening for any implant situation and for a divided or undivided framework. The 3-piece framework showed the highest values of peri-implant bone stress, regardless of the implant situation.

Conclusions: The undivided framework provides the best biomechanical environment during mandibular protrusion and opening. Protrusion movement increases the peri-implant bone stress. The most mesial implants have the lowest biomechanical risk.

Figure 1

Distribution and location of stress in peri-implant bone in 1-piece framework during 27 mm opening and protrusion (B: buccal; M: mesial surfaces). 1-piece framework images: (a) right side: between first and second molar positions during 27 mm opening; (b) right side: between first and second molar positions during protrusion; (c) left side: between first and second molar positions during 27 mm opening; (d) left side: between first and second molar positions during protrusion; (e) right side: first premolar position during 27 mm opening; (f) right side: first premolar position during protrusion; (g) left side: first premolar position during 27 mm opening; (h) left side: first premolar position during protrusion; (i) right side: canine position during 27 mm opening; (j) right side: canine position during protrusion; (k) left side: canine position during 27 mm opening; (l) left side: canine position during protrusion.

Figure 2

Distribution and location of stress on peri-implant bone in 2-piece framework during 27 mm opening and protrusion (B: buccal surface; M: mesial surface). 2-piece framework images: (a) right side: between first and second molar positions during 27 mm opening; (b) right side: between first and second molar positions during protrusion; (c) left side: between first and second molar positions during 27 mm opening; (d) left side: between first and second molar positions during protrusion; (e) right side: first premolar position during 27 mm opening; (f) right side: first premolar position during protrusion; (g) left side: first premolar position during 27 mm opening; (h) left side: first premolar position during protrusion; (i) right side: canine position during 27 mm opening; (j) right side: canine position during protrusion; (k) left side: canine position during 27 mm opening; (l) left side: canine position during protrusion.

Figure 3

Distribution and location of stress on peri-implant bone in 3-piece framework during 27 mm opening and protrusion (B: buccal; M: mesial surfaces). 3-piece framework images: (a) right side: between first and second molar positions during 27 mm opening; (b) right side: between first and second molar positions during protrusion; (c) left side: between first and second molar positions during 27 mm opening; (d) left side: between first and second molar positions during protrusion; (e) right side: first premolar position during 27 mm opening; (f) right side: first premolar position during protrusion; (g) left side: first premolar position during 27 mm opening; (h) left side: first premolar position during protrusion; (i) right side: canine position during 27 mm opening; (j) right side: canine position during protrusion; (k) left side: canine position during 27 mm opening; (l) left side: canine position during protrusion.