Probing the Influence of Hybrid Thread Design on Biomechanical Response of Dental Implants: Finite Element Study and Experimental Validation

Abstract

Objective: To perform quantitative biomechanical analysis, probing the effect of varying thread shapes in an implant for improved primary stability in prosthodontics surgery. Methods: Dental implants with square (SQR), buttress (BUT) and triangular (TRI) thread shapes or their combinations. Cone-beam computed tomography images of mandible molar zones in human subjects belonging to three age groups were used for virtual implantation of designed implants, to quantify patient-specific peri-implant bone micro-strain, using finite element analyses. The in silico analyses were carried out considering frictional contact to simulate immediate loading with a static masticatory force of 200 N. In order to validate computational biomechanics results, compression tests were performed on 3D printed implants having investigated thread architectures. Bone/implant contact areas were also quantitatively assessed. Results: Bone/implant contact was maximum for SQR implants followed by BUT and TRI implants. For all the cases, peak micro-strain was recorded in the cervical cortical bone. The combination of different thread shapes in the middle or apical part (or both) was demonstrated to improve peri-implant micro-strain particularly for BUT and TRI. Conclusions: Considering 1500-2000 micro-strain generates in peri-implant bone during regular physiological functioning, BUT-SQR, BUT-TRI-SQR, TRI-SQR-BUT, SQR, SQR-BUT-TRI design concepts were suitable for younger; BUT-TRI-SQR, BUT-SQR-TRI, TRI-SQR-BUT, SQR-BUT, SQR-TRI for middle-aged, and BUT-TRI-SQR, BUT-SQR-TRI, TRI-BUT-SQR, SQR, SQR-TRI for older group of human patients.

3D Printing of Ti-6Al-4V-Based Porous-Channel Dental Implants: Computational, Biomechanical, and Cytocompatibility Analyses

“…The contact between the bone and the implant was assumed to be frictional with a coefficient of friction of 0.30. 34 2.6.3. Assignment of Material Properties.…”

“…Assignment of Material Properties. The mandibles were assumed as isotropic, linearly elastic, and inhomogeneous in this work, 21,34 in contrast to most other investigations that assumed cortical and cancellous bones as isotropic, linearly elastic, and homogeneous. 24 By calculation of the X-ray attenuation data for every voxel (measured in Hounsfield unit, HU) from the CT scans, each of the finite elements of the bone was assigned a distinct material property (density (ρ) and Young's modulus (E) for both cortical and cancellous bones).…”

“…The discretized virtually implanted mandible was taken as input into MIMICS where each element was assigned a distinctive material property (ρ and E), corresponding to the mean of HU of all of the pixels contained inside that element and determined using the following empirical relations (Figure 1e) (1) As this material assignment protocol generated a distinct ρ and E for each finite element, the considered mandible segment had an inhomogeneous distribution of material, which was advantageous for better simulating the inherent patient-specific material distribution of bone (ν = 0.30). 21,34 Similar to the fabricated prototypes, Ti-6Al-4V was considered as the implant material (E = 110 GPa, ν = 0.33). 34 2.6.4.…”

“…As this material assignment protocol generated a distinct ρ and E for each finite element, the considered mandible segment had an inhomogeneous distribution of material, which was advantageous for better simulating the inherent patient-specific material distribution of bone (ν = 0.30). 21,34 Similar to the fabricated prototypes, Ti-6Al-4V was considered as the implant material (E = 110 GPa, ν = 0.33). 34 2.6.4.…”

“…21,34 Similar to the fabricated prototypes, Ti-6Al-4V was considered as the implant material (E = 110 GPa, ν = 0.33). 34 2.6.4. Loading and Boundary Conditions.…”