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Author: Larisa Linetska
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It was repeatedly proven that implant design, bone quality and quantity significantly influence the functional load transfer. Posterior maxilla usually offers low available bone quality and quantity, so short implants are often used in edentulism treatment. Bone strains are major stimuli of bone turnover, but their high magnitudes result in implant failure. Numerical simulation is usually applied to correlate bone and implant parameters with bone strain spectrum and evaluate implant prognosis.The aim of the study was to evaluate the impact of short plateau implants and posterior maxilla bone quality on strain level in adjacent bone to predict implant success.Four Bicon short implants with 4.5 (N), 6.0 (W) mm diameter and 5.0 (S), 8.0 (L) mm length were selected for this numerical analysis. Their 3D models were inserted in 24 posterior maxilla segment models with types III and IV bone, 1.5 (A), 1.0 (B) and 0.5 (C) mm crestal cortical bone thickness. These models were designed in Solidworks 2016 software. Bone and implant materials were assumed as linearly elastic and isotropic. Young modulus of cortical bone was 13.7 GPa, cancellous bone u2013 1.37/0.69 GPa (type III/IV). Numerical analysis of bone-implant models was carried out in FE software Solidworks Simulation. A total number of 3D FEs was up to 3,590,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7 Series Low 0u00b0 abutment. First principal strain (FPS) distributions were analyzed according to the concept of u201cminimum effective strain pathologicalu201d (MESp) by Frost. Maximal FPSs were correlated with 3000 microstrain MESp to evaluate implant prognosis.350u20267500 microstrain maximal FPSs were found in the cortical-cancellous bone interface in the vicinity of the first fin. Critical FPSs (>3000 microstrain) were observed for N implants in IV,B/C,S/L, III,B/C,S, III,C,L scenarios. For W implants, critical FPSs were found only in IV,B/C,S scenarios. Favorable FPSs (350u20263000 microstrain) were calculated in vicinity of W implants for all scenarios excluding IV,B/C,S. For N implants, favorable FPSs were observed for III,A,S/L, III,B,L. Implant diameter increase (4.5 vs. 6.0 mm) have led to 64/54/52, 78/68/70, 32/36/39, 50/53/55% FPS reduction for 1.5/1.0/0.5 mm cortical bone and III,S, III,L, IV,S, IV,L scenarios. FPS magnitudes were found sensitive to bone quality: FPS reduction in type III bone relative to type IV was -14/22/36, -95/16/39, 40/44/50, 13/44/59% for 1.5/1.0/0.5 mm and N,S, N,L, W,S, W,L scenarios.Bone strains were influenced by implant dimensions, cortical bone thickness and bone quality. 4.5u00d75.0 mm implant was recommended only for types III/IV bone and 1.5 mm cortical bone thickness, while 4.5u00d78.0 mm implant - for types III/IV bone and 1.5/1.0 mm cortical bone thickness. 6.0 mm diameter implants caused positive bone turnover for all but one scenario (6.0u00d75.0 mm implant, type IV bone, 0.5 mm cortical bone). Clinicians should consider these findings in planning of short plateau implants.
Author: Larisa Linetska
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Languages : en
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It was repeatedly proven that implant design, bone quality and quantity significantly influence the functional load transfer. Posterior maxilla usually offers low available bone quality and quantity, so short implants are often used in edentulism treatment. Bone strains are major stimuli of bone turnover, but their high magnitudes result in implant failure. Numerical simulation is usually applied to correlate bone and implant parameters with bone strain spectrum and evaluate implant prognosis.The aim of the study was to evaluate the impact of short plateau implants and posterior maxilla bone quality on strain level in adjacent bone to predict implant success.Four Bicon short implants with 4.5 (N), 6.0 (W) mm diameter and 5.0 (S), 8.0 (L) mm length were selected for this numerical analysis. Their 3D models were inserted in 24 posterior maxilla segment models with types III and IV bone, 1.5 (A), 1.0 (B) and 0.5 (C) mm crestal cortical bone thickness. These models were designed in Solidworks 2016 software. Bone and implant materials were assumed as linearly elastic and isotropic. Young modulus of cortical bone was 13.7 GPa, cancellous bone u2013 1.37/0.69 GPa (type III/IV). Numerical analysis of bone-implant models was carried out in FE software Solidworks Simulation. A total number of 3D FEs was up to 3,590,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7 Series Low 0u00b0 abutment. First principal strain (FPS) distributions were analyzed according to the concept of u201cminimum effective strain pathologicalu201d (MESp) by Frost. Maximal FPSs were correlated with 3000 microstrain MESp to evaluate implant prognosis.350u20267500 microstrain maximal FPSs were found in the cortical-cancellous bone interface in the vicinity of the first fin. Critical FPSs (>3000 microstrain) were observed for N implants in IV,B/C,S/L, III,B/C,S, III,C,L scenarios. For W implants, critical FPSs were found only in IV,B/C,S scenarios. Favorable FPSs (350u20263000 microstrain) were calculated in vicinity of W implants for all scenarios excluding IV,B/C,S. For N implants, favorable FPSs were observed for III,A,S/L, III,B,L. Implant diameter increase (4.5 vs. 6.0 mm) have led to 64/54/52, 78/68/70, 32/36/39, 50/53/55% FPS reduction for 1.5/1.0/0.5 mm cortical bone and III,S, III,L, IV,S, IV,L scenarios. FPS magnitudes were found sensitive to bone quality: FPS reduction in type III bone relative to type IV was -14/22/36, -95/16/39, 40/44/50, 13/44/59% for 1.5/1.0/0.5 mm and N,S, N,L, W,S, W,L scenarios.Bone strains were influenced by implant dimensions, cortical bone thickness and bone quality. 4.5u00d75.0 mm implant was recommended only for types III/IV bone and 1.5 mm cortical bone thickness, while 4.5u00d78.0 mm implant - for types III/IV bone and 1.5/1.0 mm cortical bone thickness. 6.0 mm diameter implants caused positive bone turnover for all but one scenario (6.0u00d75.0 mm implant, type IV bone, 0.5 mm cortical bone). Clinicians should consider these findings in planning of short plateau implants.
Author: Vitalij Nesvit
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Languages : en
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Poor bone quality and anatomic restrictions significantly influence implant success in posterior maxilla. Short implants were proposed as a reasonable choice. Implant prognosis is predetermined by stress magnitudes in bone-implant interface, which are sensitive to bone and implant parameters. Plateau implants are often preferred since they reduce bone stresses and improve implant prognosis. Precise analysis of complex biomechanical systems can only be performed by finite element (FE) method.The aim of the study was to evaluate and compare the prospect of different short plateau implants placed in atrophic posterior maxilla under 120.92 N mean maximal functional load (Mericske-Stern & Zarb, 1996).5.0 mm length and 4.0 (N), 5.0 (M), 6.0 (W) mm diameter Bicon SHORT u00ae implants were studied. Their 3D models were placed in eighteen posterior maxilla segment models with types III and IV bone. They were designed in Solidworks 2016 software and had three geometries: (A) 1.0/4.0 mm, (B) 0.75/4.25 mm and (C) 0.5/4.5 mm cortical/cancellous bone layer, their size was 30u00d79u00d711 mm (length u00d7 height u00d7 width). Implant and bone were assumed as linearly elastic and isotropic. Elasticity modulus of cortical bone was 13.7 GPa, cancellous bone u2013 1.37/0.69 (type III/IV). Bone-implant assemblies were simulated in FE software Solidworks Simulation. 4-node 3D FEs were generated with a total number of up to 5,064,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7.0 mm abutment. Von Mises equivalent stress (MES) distributions were studied to determine areas of bone overload with magnitude greater than 100 MPa in cortical and 5 MPa in cancellous bone adopted as bone tissues ultimate strength.MES maximal values were found in crestal bone. The spectrum of maximal MESs in cortical bone was between 17 MPa (III,A,W) and 55 MPa (IV,C,N). They were influenced by cortical bone thickness, bone quality and implant dimensions. MES reduction due to cortical bone thickness increase from 0.5 to 1.0 mm was 25, 35, 17% for N, M and W implants and type IV bone, while for type III it was 25, 34, 19%. Cancellous bone quality was found to have a substantial impact on biomechanical state of cortical bone: two-fold reduction of elasticity modulus (1.37 versus 0.69 GPa) corresponded to 24.2, 30.2 and 26.5% MES rise for N, M and W implants and 1.0 mm cortical bone, 26.6, 23.6 and 20.5% MES rise for N, M and W implants and 0.75 mm cortical bone, and 25.0, 23.1 and 23.8% MES rise for N, M and W implants and 0.5 mm cortical bone. MESs magnitudes in cancellous bone were found below its ultimate strength (5 MPa) only for M and W implants placed into 1.0 mm cortical bone.Stresses in posterior maxilla were influenced by cortical bone thickness, bone quality and especially implant diameter. Under 120.92 N load and 0.5u20261.0 mm cortical bone, failure of 4.0u00d75.0 mm, 5.0u00d75.0 mm, 6.0u00d75.0 mm Bicon SHORTu00ae implants was highly unlikely from the viewpoint of cortical bone overload. To avoid cancellous bone overstress, both 5.0u00d75.0 and 6.0u00d75.0 mm implants were found applicable, but only in case of 1.0 mm cortical bone.
Author: Oleg Yefremov
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Languages : en
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Insufficient bone remains challenging for implantologists, especially in posterior maxilla. Short implants are indispensable in such situations. Implant design, bone quality and quantity significantly influence the functional load transfer. Bone strains are major stimuli of bone turnover, but their high magnitudes result in implant failure. Numerical analysis is necessary to correlate bone and implant parameters with bone strain spectrum and to evaluate implant prospect.The aim of the study was to evaluate the impact of Bicon Integra-CPu2122 implants and bone quality on strain levels in adjacent bone to predict implant success/failure in atrophic posterior maxilla.Nine Bicon Integra-CPu2122 implants with 4.5 (N), 5.0 (M), 6.0 (W) mm diameter and 5.0 (S), 6.0 (I), 8.0 (L) mm length were selected for this comparative study. Their 3D models were placed in 36 posterior maxilla segment models with types III and IV bone, 1.0 (A) and 0.5 (B) mm crestal cortical bone thickness. These models were designed in Solidworks 2016 software. All materials were assumed as linearly elastic and isotropic. Elasticity modulus of cortical bone was 13.7 GPa, cancellous bone u2013 1.37/0.69 GPa (type III/IV). Bone-implant assemblies were analyzed in FE software Solidworks Simulation. A total number of 4-node 3D FEs was up to 3,580,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7.0 mm abutment. First principal strain (FPS) distributions were studied according to the concept of u201cminimum effective strain pathologicalu201d (MESp) by Frost. Maximal FPSs were correlated with 3000 ustrain MESp to evaluate the prognosis of each implant.Maximal FPSs spectrum 200u20267500 ustrain was found in the cortical-cancellous bone interface. Critical FPSs (>3000 ustrain) were observed for N implants for IV,A/B,S/I/L and III,A,S/I scenarios. For M and W implants, critical FPSs were found only for M,III/IV,A,S/I, M,IV,B,S/I and W,IV,A,S scenarios. Favorable FPSs (200u20263000 ustrain) were calculated in vicinity of W implants for all scenarios excluding IV,A,S. For M implants, favorable FPSs were observed for IV,A/B,L, III,A,L and III,B,S/I/L scenarios, and only III,A,L and III,B,S/I/L for N implants. Implant diameter increase (4.5 vs. 6.0 mm) have led to 71/87, 74/88, 66/88, 57/80, 60/81, 56/73% FPS reduction for 1.0/0.5 mm cortical bone and III,S, III,I, III,L, IV,S, IV,I, IV,L scenarios. FPS magnitudes were found sensitive to bone quality: FPS reduction in type III bone relative to type IV was 25/46, 26/48, 32/48, 17/41, 20/46, 33/50, 48/64, 52/67, 47/76% for 1.0/0.5 mm and N,S, N,I, N,L, M,S, M,I, M,L, W,S, W,I, W,L scenarios.Bone strains were influenced by implant dimensions, cortical bone thickness and bone quality. 4.5 mm diameter implants with the largest length were recommended only for type III bone. 5.0u00d78.0 mm implant was suitable for both bone types and cortical bone thickness, shorter implants u2013 only for type III and 0.5 mm cortical bone. 6.0 mm diameter implants caused positive bone turnover balance for all but one scenarios. Clinicians should consider these findings in planning of short plateau implants.
Author: Igor Linetskiy
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Languages : en
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Bicon short implants have successfully proven themselves in the maxillary molar region with insufficient bone height and poor bone quality. To improve crestal bone healing, autogenous bone is placed in the gap between implant neck and implant bed. But even for such approach, the quality of the augmented bone is not fully predictable, though cortical bone strength is the key criterion of implant success. Finite element (FE) method allows precise analysis of this complex biomechanical system. The aim of this study was to evaluate the prospect of different-sized short plateau implants placed in atrophic posterior maxilla depending on the degree of augmented bone quality under oblique functional loading. 5.0 mm length and 4.0 (N), 5.0 (M), 6.0 (W) mm diameter Bicon SHORT u00ae implants were selected for this comparative study. Their 3D models were placed crestally in twelve posterior maxilla segment models with type III bone. They were designed using CT images in Solidworks 2016 software with 1.0 mm crestal/sinus cortical and 4.0 mm cancellous bone layers. Each model geometry was 10u00d730u00d719 mm. Implant and bone were assumed as linearly elastic and isotropic. Elasticity moduli of cortical/cancellous bone were 13.7/1.37 GPa. Four degrees of augmented bone quality were simulated: 100% (E1=13.7 GPa), 75% (E2=10.3 GPa), 50% (E3=6.85 GPa) and 25% (E4=3.43 GPa). Bone-implant assemblies were analyzed in FE software Solidworks Simulation. 4-node 3D FEs were generated with a total number of up to 4,040,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7.0 mm abutment. Von Mises equivalent stress (MES) distributions were studied to determine the areas of bone overload. Analysis of MESs distributions in cortical bone has showed that their maximal magnitudes were found in crestal area. The spectrum of maximal MESs in augmented bone was between 9.5 MPa (W,E4) and 37 MPa (N,E1). They were influenced by implant diameter and augmented bone quality. MES reduction due to diameter increase from 4.0 to 6.0 mm was 52.7, 54.5, 55.4 and 54.8% for E1, E2, E3 and E4 bone quality. MES reduction due to two-fold augmented bone quality decrease (E1 versus E3) was 24.3, 30.2 and 28.6% for N, M and W implants. However, reduction of augmented bone quality caused significant overload of cancellous bone (5-17 MPa). Only for E1 bone, maximal MES in cancellous bone was approximately 5-7 MPa. In all other scenarios, maximal MES substantially exceeded 5 MPa strength of cancellous bone. N implants were found to be the most susceptible to the quality of augmented bone: E1 to E4 bone quality reduction has led to 126 and 82% MES rise for N and W implants. Under mean maximal functional loading, sufficient influence of augmented bone quality on crestal bone-implant interface was established. However, crestal bone overload is highly unlikely because MESs were found to be lesser than 100 MPa ultimate bone strength. Contrarily, E2-E4 bone quality scenarios are critical from the viewpoint of cancellous bone overload and implant failure. Placement of wider implant allows to decrease this risk.
Author: Igor Linetskiy
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Languages : en
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Plateau short implants have become popular in critical cases of edentulous posterior maxilla. For insufficient bone height, the standard protocol of subcrestal placement is inapplicable, so crestal insertion becomes the only option. Unfortunately, it often leads to stresses increase in bone-implant interface, which causes implant failure. Finite element (FE) method provides biomechanical evaluation of bone-implant structures and influence of bone quality and implant parameters on bone stresses.The aim of the study was to evaluate the impact of crestal placement of particular short plateau implants on stress magnitudes in atrophic posterior maxilla under oblique functional loading to predict bone overload and implant failure.Nine Bicon Integra-CPu2122 implants with 5.0 (S), 6.0 (I), 8.0 (L) mm length and 4.5 (N), 5.0 (M), 6.0 (W) mm diameter were selected for this study. Their 3D models were placed in 36 posterior maxilla segment models with types III and IV bone, 1.0 (A) and 0.5 (B) mm crestal cortical bone thickness. These models were designed using CT images in Solidworks 2016 software. Implant and bone were assumed as linearly elastic and isotropic. Elasticity modulus of cortical bone was 13.7 GPa, cancellous bone u2013 1.37 GPa (type III) and 0.69 GPa (type IV). Bone-implant assemblies were analyzed in FE software Solidworks Simulation. 4-node 3D FEs were generated with a total number of up to 2,518,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7.0 mm abutment. Von Mises equivalent stress (MES) distributions in surrounding bone were studied to determine the areas of bone overload with magnitude >100 MPa in cortical and >5 MPa in cancellous bone.Maximal magnitudes of MESs were found in crestal cortical bone in the plane of critical bone-implant interface. The spectrum of maximal MESs was between 15.2 and 40.5 MPa. The highest MESs were found for all N,IV,B scenarios (34.4-40.5 MPa), while the smallest magnitudes were determined for all W,III,A scenarios (15.2-16.5 MPa). For all tested implants, maximal MES magnitudes were significantly influenced by cortical bone thickness and implant dimensions, yet they were not susceptible to bone quality: for type IV bone scenarios compared to type III, MES increase was within the range of 12-19%. Besides, for 0.5 mm cortical bone thickness scenarios, 18-19% increase was determined and it was not dependent on implant diameter. MESs around N implants were found to be prone to their length decrease, especially for 0.5 mm cortical bone.The outcomes of this study enhance understanding of the stress characteristics in the maxilla surrounding different-sized short plateau implants. Studied Bicon implants have not caused 100 MPa ultimate stresses in crestal bone under mean, and even 275 N maximum experimental load. This study supports clinical success of plateau implants in posterior maxilla due to their low susceptibility to poor bone quality. It provides a rationale for appropriate implant selection for posterior maxilla.
Author: Larisa Linetska
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Languages : en
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Among other reasons, dental implants often fail due to bone loss. Because of reduced length, short implants should be more susceptible to bone loss, especially if placed crestally. As a result of osseointegration loss, bone overload may take place under physiological functional loading, which, in turn, leads to bone loss progression. So, implant long-term prognosis would be heavily compromised.The aim of this study was to evaluate the role of implant diameter on long-term prognosis of short plateau implants in posterior maxilla considering bone loss.In order to compare load-carrying capacities of fully and partially osseointegrated (0.2 mm annual bone loss) 4.5 (N), 5.0 (M) and 6.0 mm (W) diameter and 5.0 mm length Bicon Shortu00ae implants, the concept of ultimate functional load (UFL) was proposed (Demenko, 2011). The implants 3D models were placed crestally and bicortically in posterior maxilla models with type III bone and 1.0 mm cortical crestal and sinus bone, which were generated in Solidworks 2016 software with a total number of up to 2,840,000 4-node 3D finite elements (FEs). Materials were assumed as linearly elastic and isotropic. Young moduli of cortical/cancellous bone were 13.7/1.37 GPa and cortical bone compression strength was 100 MPa. The models were analyzed in FE software Solidworks Simulation. 120.92 N oblique load was applied to the center of 7.0 mm abutment. Maximal von Mises stresses (MESs) were evaluated in bone-implant interface to determine UFL magnitudes for fully and partially osseointegrated implants.Maximal MESs for osseointegrated implants (14u202628 MPa) were found on the surface of crestal cortical bone. For implants with 0.2, 0.4, 0.6, 0.8, 1.0 mm bone loss, they were observed in migrating critical points inside crestal cortical bone: 23u202635, 32u202641, 38u202645, 41u202648, 43u202650 MPa. For osseointegrated implants, UFL magnitudes were 432u2026864 N. For the ones with 0.2, 0.4, 0.6, 0.8, 1.0 mm bone loss, UFL magnitudes were 345u2026526, 295u2026378, 269u2026318, 252u2026295, 242u2026278 N. So, after 5 years in function (1.0 mm bone loss), the following reduction of implant load-bearing capacity was determined: 44, 58 and 69% for N, M and W implants. Comparing to osseointegrated state, UFL drop with 0.2, 0.4, 0.6, 0.8 and 1.0 mm bone loss was found: 20, 32, 38, 42, 44% for N; 33, 46, 52, 56, 58% for M; 39, 56, 63, 66, 68% for W implants. It was determined that W implant had 53, 28, 18, 17, 15% UFL magnitude increase for 0.2, 0.4, 0.6, 0.8, 1.0 mm bone loss relative to N implant.All UFL magnitudes were found much higher than mean maximal functional loading (120.92 N). Furthermore, for all scenarios, UFL magnitudes were above 275 N maximal functional loading for molar area. By evaluating implant load-bearing capacity reduction, dental professionals may consider the factor of implant longevity in selection of a proper implant diameter.
Author: Larisa Linetska
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Languages : en
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Short finned implants are often applied in critical cases of edentulous posterior maxilla with no available bone for subcrestal implant placement. Resulting higher stresses in crestal cortical bone lead to its overload and subsequent implant failure. Finite element (FE) method provides biomechanical evaluation of bone-implant structures and influence of bone quality and implant parameters on bone stresses.The aim of the study was to evaluate the impact of crestal placement of short finned implants on stress magnitudes in atrophic posterior maxilla under oblique functional loading to predict bone overload and implant failure.Four Bicon Integra-CPu2122 implants with 4.5, 6.0 mm diameter and 5.0, 8.0 mm length were selected for this evaluation. Their 3D models were placed in 12 posterior maxilla segment models with type IV bone, 1.5, 1.0 and 0.5 mm crestal cortical bone thickness. These models were designed using CT images in Solidworks 2016 software. Implant and bone were assumed as linearly elastic and isotropic. Elasticity modulus of cortical bone was 13.7 GPa, cancellous bone u2013 0.69 GPa. Bone-implant assemblies were analyzed in FE software Solidworks Simulation. 4-node 3D FEs were generated with a total number of up to 2,820,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7 Series Low 0u00b0 abutment. Von Mises equivalent stress (MES) distributions in surrounding bone were studied to determine the areas of bone overload with magnitude >100 MPa in cortical bone.Maximal magnitudes of MESs were found in crestal cortical bone. The spectrum of maximal MESs was between 14.0 and 47.0 MPa. The highest MESs were found for 4.5u00d75.0 mm implant, while the smallest magnitudes were determined for 6.0u00d78.0 mm implant. For tested implants, maximal MES magnitudes were significantly influenced by cortical bone thickness and implant dimensions: for 0.5, 1.0 and 1.5 mm cortical bone thickness and diameter increase from 4.5 to 6.0 mm, MES drop was 48, 47, 43% for 5.0 mm length implants, while for 8.0 mm length implants it was 48, 48, 46%. In 0.5 mm cortical bone thickness, maximal MESs varied within 15-17% range. For 4.5/6.0 mm diameter implants, bone thickness increase from 0.5 to 1.5 mm corresponded to 43/35% MES drop for 5.0 mm length implants and 33/30% - for 8.0 mm length implants, while two-fold bone thickness increase from 0.5 to 1.0 mm corresponded to 21/19% MES drop for 5.0 mm length implants and 15/15% - for 8.0 mm length implants.The study enhances perception of bone stress issues in the posterior maxilla relative to cortical bone thickness. Evaluated finned implants have not exceeded 100 MPa ultimate cortical bone strength. For 1.5 mm cortical bone thickness, no sensitivity to implant length was found. This FE study approves the finned implants clinical success in posterior maxilla due to their low susceptibility to poor bone quality. It provides a rationale for appropriate implant selection.
Author: Igor Linetskiy
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Languages : en
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Implant prognosis is predetermined by stresses in the bone-implant interface. Plateau implants are considered to be highly successful since they reduce bone stress concentrations. For cases with lack of bone height, crestal placement remains a reasonable alternative. Otherwise, subcrestal placement of short implants is advised since it is considered as a crucial factor in preservation of crestal bone. For such scenario, bone biomechanical state is directly dependent on implant insertion depth. The aim of the study was to compare the impact of crestal or subcrestal short plateau implant placement in different bone quality conditions on peri-implant bone stresses and to assess implant prognosis under 120.92 N mean maximal oblique functional loading.5.0u00d75.0 mm Bicon Integra-CPu2122 implant was selected for this comparative study. Its 3D models were placed in four posterior maxilla models with types III and IV bone with 1.0 mm cortical bone thickness. Different insertion depths were simulated: the implant neck was in crestal (C) and -1, -2 and -3 mm subcrestal (S1, S2, S3) positions. All materials were assumed to be linear elastic and isotropic. Elastic moduli of cortical, type III/IV cancellous bone and implants were set to 13.7, 1.37/0.69 and 114 GPa, and Poissonu2019s ratio was 0.3 for all materials. Finite element (FE) models were analyzed in Solidworks Simulation software. 4-node 3D FEs were generated with a total number of up to 3,570,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7.0 mm abutment. Von Mises equivalent stress (MES) distributions in surrounding bone were studied to determine the areas of bone overload with magnitude >100 MPa in cortical and >5 MPa in cancellous bone.Maximal MES magnitudes for all scenarios were found at the implant neck. For C scenario, maximal MES magnitudes were found in crestal cortical bone: 21/28 MPa (type III/IV bone). Maximal MES magnitudes in cancellous bone were approximately 5 MPa for both bone types. For S1, S2 and S3 scenarios, since there was no contact between implant and cortical bone, maximal MES magnitudes were located in cancellous bone at the implant neck. For S1 scenarios they were 18u202620 MPa, for S2 and S3 scenarios they were 13u202614 MPa, for both bone quality types. Another critical MES area was located at the implant root: for C scenario, maximal MES magnitudes were 2 MPa for both bone quality types, for S1 scenario they were 2.5/3.5 MPa, for S2 u2013 3.5/4.0 MPa and for S3 u2013 7/10 MPa (for type III/IV bone).It was found that 5.0u00d75.0 mm Bicon Integra-CPu2122 implant in crestal placement generated safe bone MESs and offered favorable clinical prospect. For all subcrestal scenarios, the implant caused exceeding MESs in cancellous bone due to absence of interface between the implant and cortical bone. However, the tested Bicon implant showed low susceptibility to bone quality worsening at studied levels of subcrestal placement. This finding confirms positive clinical experience of Bicon plateau implants.
Author: Igor Linetskiy
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Languages : en
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Book Description
Short implants are indispensable in posterior maxilla with insufficient bone height. Implant design, bone quality and degree of bone loss predetermine safe functional load transfer to adjacent bone. Adequate bone strains are key stimuli of bone turnover, but their extreme magnitudes lead to implant failure. Computer simulation allows to correlate bone and implant parameters with bone strain spectrum and to evaluate implant perspective.The aim of the study was to evaluate the impact of plateau implants and bone quality on strain levels in adjacent bone at several levels of bone loss to assess implant prognosis.Cortical and cancellous bone first principal strains (FPSs) were selected to evaluate bone turnover around fully and partially osseointegrated 4.5 (N), 5.0 (M) and 6.0 mm (W) diameter and 5.0 mm length Bicon SHORTu00ae implants at five levels of bone loss from 0.2 to 1.0 mm. Implant 3D models were placed crestally in corresponding posterior maxilla segment models with type III bone and 1.0 mm cortical crestal and sinus bone layers. The models were designed in Solidworks 2016 software. All materials were assumed as linearly elastic and isotropic. Elasticity modulus of cortical bone was 13.7 GPa, cancellous bone u2013 1.37 GPa. Bone-implant assemblies were analyzed in FE software Solidworks Simulation. A total number of 4-node 3D FEs was up to 3,450,000. 120.92 N mean maximal oblique load (molar area) was applied to the center of 7 Series Low 0u00b0 abutment. Maximal FPSs were correlated with 3000 microstrain minimum effective strain pathological (MESp) to evaluate bone turnover around the implants.Maximal FPSs for osseointegrated implants (1800u20263270 microstrain) were found in the cancellous bone at the first fin edge. For implants with bone loss, they were observed at the same location and were significantly dependent on bone loss level (2140u20263600, 2300u20264100, 2800u20264900, 3500u20265900 and 4200u20267000 microstrain for 0.2, 0.4, 0.6, 0.8 and 1.0 mm bone loss). Maximal FPSs were also substantially dependent on implant diameter: diameter increase from 4.5 to 6.0 mm have led to 41, 44, 43, 41, 40% FPS decrease for 0.2, 0.4, 0.6, 0.8 and 1.0 mm bone loss. Comparing to the osseointegrated implants, the following FPS increase on five bone loss levels was determined: for N implants it was 10, 25, 50, 80 and 114%, for M implants u2013 12, 32, 62, 92, 131%, for W implants u2013 19, 28, 56, 94 and 133%.Bone turnover was found to be significantly influenced by implant diameter and bone loss level. 4.5 mm diameter implant is not recommended for type III bone because bone strains exceed 3000 microstrain threshold even for the osseointegrated implant. 6.0 mm diameter implant caused positive bone turnover balance for up to 0.6 mm bone loss, while 5.0 mm u2013 only for up to 0.3 mm bone loss. Clinicians should consider these findings in treatment with short plateau implants.
Author: Boyd J. Tomasetti
Publisher: Springer Nature
ISBN: 3030441997
Category : Medical
Languages : en
Pages : 334
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Book Description
This comprehensive guide to short implants will take the reader through their research and development, explain the clinical indications, evaluate the outcomes achieved with various implants, and explore restorative and laboratory considerations. Short implants have steadily gained greater market share in the last decade as practitioners sought alternatives to traditional length implants in order to avoid grafting procedures. Current manufacturers offer a variety of implant lengths and widths, allowing surgeons and restorative dentists the ability to select the best implant for each clinical circumstance. Cutting edge information is provided on the research and clinical results achieved utilizing a range of implants, specifically those developed by Nobel Biocare, Straumann, Jack Hahn, and Bicon. Readers will also find an extensive description of the role of ultra-short implants involving reconstruction in both cleft patients and cancer patients who have lost portions of their mandible and/or maxilla. This book is a must-have for those interested in learning how the use of short and ultra-short implants offers both surgeons and restorative dentists an opportunity to stand out from those that use only the traditional length implants.
