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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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Configuration of the dental implant/bone system. In the D2 model, a core of dense cancellous bone was covered by a thick layer of compact bone with a width of 2 mm. The geometric configurations of D3 and D4 models were similar to those of the D2 model, but the width of the compact bone layers was reduced to 1 mm.
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fig2: Configuration of the dental implant/bone system. In the D2 model, a core of dense cancellous bone was covered by a thick layer of compact bone with a width of 2 mm. The geometric configurations of D3 and D4 models were similar to those of the D2 model, but the width of the compact bone layers was reduced to 1 mm.

Mentions: The five 3D solid V-threaded implants were modeled under similar conditions. The bone block had dimensions of 15 mm × 25 mm × 20 mm representing buccolingual × mesiodistal × inferosuperior surfaces. As per the classification of Lekholm and Zarb [33], there are four distinctly different bone qualities (D1, D2, D3, and D4). In this study, we simulated the latter three types (D2, D3, and D4). D1 bone quality was not simulated as it consists of compact bone only. In the D2 model, a core of dense cancellous bone was covered by a thick layer of compact bone with a width of 2 mm. The geometric configurations of D3 and D4 models were similar to those of the D2 model, but the width of the compact bone layers was reduced to 1 mm. In the D3 model, a thin layer (1 mm) of cortical bone surrounds a core of dense trabecular bone of favorable strength (Figure 2). In the D4 model, a thin layer (1 mm) of cortical bone surrounds a core of low-density trabecular bone. The thickness of the compact bone set in the 3D models was based on previous studies [34–36]. In the above models, the mesial and distal sides were not covered by compact bone.


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)

Configuration of the dental implant/bone system. In the D2 model, a core of dense cancellous bone was covered by a thick layer of compact bone with a width of 2 mm. The geometric configurations of D3 and D4 models were similar to those of the D2 model, but the width of the compact bone layers was reduced to 1 mm.
© Copyright Policy
Related In: Results  -  Collection

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

fig2: Configuration of the dental implant/bone system. In the D2 model, a core of dense cancellous bone was covered by a thick layer of compact bone with a width of 2 mm. The geometric configurations of D3 and D4 models were similar to those of the D2 model, but the width of the compact bone layers was reduced to 1 mm.
Mentions: The five 3D solid V-threaded implants were modeled under similar conditions. The bone block had dimensions of 15 mm × 25 mm × 20 mm representing buccolingual × mesiodistal × inferosuperior surfaces. As per the classification of Lekholm and Zarb [33], there are four distinctly different bone qualities (D1, D2, D3, and D4). In this study, we simulated the latter three types (D2, D3, and D4). D1 bone quality was not simulated as it consists of compact bone only. In the D2 model, a core of dense cancellous bone was covered by a thick layer of compact bone with a width of 2 mm. The geometric configurations of D3 and D4 models were similar to those of the D2 model, but the width of the compact bone layers was reduced to 1 mm. In the D3 model, a thin layer (1 mm) of cortical bone surrounds a core of dense trabecular bone of favorable strength (Figure 2). In the D4 model, a thin layer (1 mm) of cortical bone surrounds a core of low-density trabecular bone. The thickness of the compact bone set in the 3D models was based on previous studies [34–36]. In the above models, the mesial and distal sides were not covered by compact bone.

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