Loading Pressure Induced by 4 mm Implants on the Inferior Alveolar Nerve: A 3D Finite Element Analysis Model

Area of Science:

• Biomaterials Science
• Biomechanics
• Oral and Maxillofacial Surgery

Background:

• Inferior alveolar nerve (IAN) injury is a significant risk during implant placement in atrophic posterior mandibles.
• Occlusal loading of implants can also lead to IAN complications.
• Severe posterior mandibular atrophy presents unique challenges for dental implant surgery.

Purpose of the Study:

• To investigate the stress transmission to the inferior alveolar nerve (IAN) from 4 mm implants during occlusal loading.
• To evaluate the safety of placing implants at reduced distances from the IAN in atrophic mandibles.
• To determine the pressure distribution on the IAN under varying implant-to-nerve proximities.

Main Methods:

• Creation of a 3D computer-aided design (CAD) model of the mandible with simplified cortical and trabecular bone structures.
• Utilization of Finite Element Analysis (FEA) to simulate pressure distribution and stress/strain deformations.
• Analysis of pressure on the IAN at implant-to-nerve distances of 1.5 mm, 0.5 mm, and 0.1 mm.

Main Results:

• Pressure distribution on the IAN remained below 0.026 MPa across all tested distances, including 0.1 mm.
• This pressure level is below the threshold known to block nerve impulses.
• Cortical bone stiffness was identified as a critical factor in mitigating stress transmission to the IAN.

Conclusions:

• Ultra-short implants (4 mm) can be placed as close as 0.1 mm to the IAN under FEA conditions without exceeding critical pressure thresholds.
• The inherent rigidity of the cortical bone effectively reduces pressure transmission to the nerve.
• These findings suggest expanded indications for ultra-short implants, even in mandibles with minimal residual bone height (4 mm).