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Influence of thread pitch, helix angle, and compactness on micromotion of immediately loaded implants in three types of bone quality: a three-dimensional finite element analysis.

Ma P, Xiong W, Tan B, Geng W, Liu J, Li W, Li D - Biomed Res Int (2014)

Bottom Line: We found that vertical relative displacement was affected by thread pitch, helix angle, and compactness.Under vertical loading, displacement was positively correlated with thread pitch and helix angle but negatively with compactness.Bone type amplifies the influence of thread pattern on displacement.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Implantology, Beijing Stomatological Hospital of Capital Medical University, Beijing 100050, China ; Department of Oral Implantology, School of Stomatology, State Key Laboratory of Military Stomatology, The Fourth Military Medical University, Xi'an, Shanxi 710032, China.

ABSTRACT
This study investigated the influence of thread pitch, helix angle, and compactness on micromotion in immediately loaded implants in bone of varying density (D2, D3, and D4). Five models of the three-dimensional finite element (0.8 mm pitch, 1.6 mm pitch, 2.4 mm pitch, double-threaded, and triple-threaded implants) in three types of bone were created using Pro/E, Hypermesh, and ABAQUS software. The study had three groups: Group 1, different pitches (Pitch Group); Group 2, same compactness but different helix angles (Angle Group); and Group 3, same helix angle but different compactness (Compact Group). Implant micromotion was assessed as the comprehensive relative displacement. We found that vertical relative displacement was affected by thread pitch, helix angle, and compactness. Under vertical loading, displacement was positively correlated with thread pitch and helix angle but negatively with compactness. Under horizontal loading in D2, the influence of pitch, helix angle, and compactness on implant stability was limited; however, in D3 and D4, the influence of pitch, helix angle, and compactness on implant stability is increased. The additional evidence was provided that trabecular bone density has less effect on implant micromotion than cortical bone thickness. Bone type amplifies the influence of thread pattern on displacement.

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Four coordinate points were defined to the collar, tip, and corresponding bone quality of each type of implant model. Four coordinate points were nodes in model meshing, with each point located in the same position in each model.
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fig3: Four coordinate points were defined to the collar, tip, and corresponding bone quality of each type of implant model. Four coordinate points were nodes in model meshing, with each point located in the same position in each model.

Mentions: The combined solid model was transferred to Hypermesh 7.0 (Hypermesh 7.0 Inc., Providence, RI, USA) to create a finite element meshed model for later analysis. To guarantee the comparability of the model, four coordinate points were defined to the collar, tip, and corresponding bone type (compact and cancellous) in each style of implant model, and the points in all of the implant models were the same for the collar and the tip, respectively. The four coordinate points are nodes in the model meshing, with each point located in the same position in each model (Figure 3). The tetra meshing was chosen to refine the implants and bone interfaces (Figure 3). Each mathematical model included approximately 147256–163298 nodes and 83710–92522 solid elements. These models were then input into the finite element package (ABAQUS Inc., Providence, RI, USA). The accuracy of a 3D finite element model is related to the element mesh density in relation to the element configuration chosen. This can be assessed objectively by repeated calculations for increased mesh refinement and checking the convergence of the micromotion results. The convergence criteria were set as the change of displacement variations of <3% for models with different element sizes.


Influence of thread pitch, helix angle, and compactness on micromotion of immediately loaded implants in three types of bone quality: a three-dimensional finite element analysis.

Ma P, Xiong W, Tan B, Geng W, Liu J, Li W, Li D - Biomed Res Int (2014)

Four coordinate points were defined to the collar, tip, and corresponding bone quality of each type of implant model. Four coordinate points were nodes in model meshing, with each point located in the same position in each model.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109075&req=5

fig3: Four coordinate points were defined to the collar, tip, and corresponding bone quality of each type of implant model. Four coordinate points were nodes in model meshing, with each point located in the same position in each model.
Mentions: The combined solid model was transferred to Hypermesh 7.0 (Hypermesh 7.0 Inc., Providence, RI, USA) to create a finite element meshed model for later analysis. To guarantee the comparability of the model, four coordinate points were defined to the collar, tip, and corresponding bone type (compact and cancellous) in each style of implant model, and the points in all of the implant models were the same for the collar and the tip, respectively. The four coordinate points are nodes in the model meshing, with each point located in the same position in each model (Figure 3). The tetra meshing was chosen to refine the implants and bone interfaces (Figure 3). Each mathematical model included approximately 147256–163298 nodes and 83710–92522 solid elements. These models were then input into the finite element package (ABAQUS Inc., Providence, RI, USA). The accuracy of a 3D finite element model is related to the element mesh density in relation to the element configuration chosen. This can be assessed objectively by repeated calculations for increased mesh refinement and checking the convergence of the micromotion results. The convergence criteria were set as the change of displacement variations of <3% for models with different element sizes.

Bottom Line: We found that vertical relative displacement was affected by thread pitch, helix angle, and compactness.Under vertical loading, displacement was positively correlated with thread pitch and helix angle but negatively with compactness.Bone type amplifies the influence of thread pattern on displacement.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Implantology, Beijing Stomatological Hospital of Capital Medical University, Beijing 100050, China ; Department of Oral Implantology, School of Stomatology, State Key Laboratory of Military Stomatology, The Fourth Military Medical University, Xi'an, Shanxi 710032, China.

ABSTRACT
This study investigated the influence of thread pitch, helix angle, and compactness on micromotion in immediately loaded implants in bone of varying density (D2, D3, and D4). Five models of the three-dimensional finite element (0.8 mm pitch, 1.6 mm pitch, 2.4 mm pitch, double-threaded, and triple-threaded implants) in three types of bone were created using Pro/E, Hypermesh, and ABAQUS software. The study had three groups: Group 1, different pitches (Pitch Group); Group 2, same compactness but different helix angles (Angle Group); and Group 3, same helix angle but different compactness (Compact Group). Implant micromotion was assessed as the comprehensive relative displacement. We found that vertical relative displacement was affected by thread pitch, helix angle, and compactness. Under vertical loading, displacement was positively correlated with thread pitch and helix angle but negatively with compactness. Under horizontal loading in D2, the influence of pitch, helix angle, and compactness on implant stability was limited; however, in D3 and D4, the influence of pitch, helix angle, and compactness on implant stability is increased. The additional evidence was provided that trabecular bone density has less effect on implant micromotion than cortical bone thickness. Bone type amplifies the influence of thread pattern on displacement.

Show MeSH