Michele Calì1, Elisabetta Maria Zanetti2, Salvatore Massimo Oliveri3, Riccardo Asero4, Stefano Ciaramella5, Massimo Martorelli6, Cristina Bignardi7. 1. Electric, Electronics and Computer Engineering Department, University of Catania, V.le A. Doria, 6, 95125 Catania, Italy. Electronic address: mcali@dii.unict.it. 2. Department of Engineering - University of Perugia, Via Duranti 67, 06125 Perugia, Italy. Electronic address: elisabetta.zanetti@unipg.it. 3. Electric, Electronics and Computer Engineering Department, University of Catania, V.le A. Doria, 6, 95125 Catania, Italy. 4. Studio Odontoiatrico Asero, Via Generale Cantore 23, 95123 Catania, Italy. Electronic address: riccardoasero@me.com. 5. Department of Industrial Engineering, Fraunhofer JL IDEAS - University of Naples Federico II, P.le Tecchio, 80, 80125 Napoli, Italy. Electronic address: stefano.ciaramella@unina.it. 6. Department of Industrial Engineering, Fraunhofer JL IDEAS - University of Naples Federico II, P.le Tecchio, 80, 80125 Napoli, Italy. 7. DIMEAS, Politecnico di Torino, Cso Duca degli Abruzzi, 24, 10129 Torino, Italy. Electronic address: cristina.bignardi@polito.it.
Abstract
OBJECTIVE: To assess the influence of implant thread shape and inclination on the mechanical behaviour of bone-implant systems. The study assesses which factors influence the initial and full osseointegration stages. METHODS: Point clouds of the original implant were created using a non-contact reverse engineering technique. A 3D tessellated surface was created using Geomagic Studio® software. From cross-section curves, generated by intersecting the tessellated model and cutting-planes, a 3D parametric CAD model was created using SolidWorks® 2017. By the permutation of three thread shapes (rectangular, 30° trapezoidal, 45° trapezoidal) and three thread inclinations (0°, 3° or 6°), nine geometric configurations were obtained. Two different osseointegration stages were analysed: the initial osseointegration and a full osseointegration. In total, 18 different FE models were analysed and two load conditions were applied to each model. The mechanical behaviour of the models was analysed by Finite Element (FE) Analysis using ANSYS® v. 17.0. Static linear analyses were also carried out. RESULTS: ANOVA was used to assess the influence of each factor. Models with a rectangular thread and 6° inclination provided the best results and reduced displacement in the initial osseointegration stages up to 4.58%. This configuration also reduced equivalent VM stress peaks up to 54%. The same effect was confirmed for the full osseointegration stage, where 6° inclination reduced stress peaks by up to 62%. SIGNIFICANCE: The FE analysis confirmed the beneficial effect of thread inclination, reducing the displacement in immediate post-operative conditions and equivalent VM stress peaks. Thread shape does not significantly influence the mechanical behaviour of bone-implant systems but contributes to reducing stress peaks in the trabecular bone in both the initial and full osseointegration stages.
OBJECTIVE: To assess the influence of implant thread shape and inclination on the mechanical behaviour of bone-implant systems. The study assesses which factors influence the initial and full osseointegration stages. METHODS: Point clouds of the original implant were created using a non-contact reverse engineering technique. A 3D tessellated surface was created using Geomagic Studio® software. From cross-section curves, generated by intersecting the tessellated model and cutting-planes, a 3D parametric CAD model was created using SolidWorks® 2017. By the permutation of three thread shapes (rectangular, 30° trapezoidal, 45° trapezoidal) and three thread inclinations (0°, 3° or 6°), nine geometric configurations were obtained. Two different osseointegration stages were analysed: the initial osseointegration and a full osseointegration. In total, 18 different FE models were analysed and two load conditions were applied to each model. The mechanical behaviour of the models was analysed by Finite Element (FE) Analysis using ANSYS® v. 17.0. Static linear analyses were also carried out. RESULTS: ANOVA was used to assess the influence of each factor. Models with a rectangular thread and 6° inclination provided the best results and reduced displacement in the initial osseointegration stages up to 4.58%. This configuration also reduced equivalent VM stress peaks up to 54%. The same effect was confirmed for the full osseointegration stage, where 6° inclination reduced stress peaks by up to 62%. SIGNIFICANCE: The FE analysis confirmed the beneficial effect of thread inclination, reducing the displacement in immediate post-operative conditions and equivalent VM stress peaks. Thread shape does not significantly influence the mechanical behaviour of bone-implant systems but contributes to reducing stress peaks in the trabecular bone in both the initial and full osseointegration stages.