Limits...
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.

Show MeSH
Increasing rates of comprehensive relative displacement between the Pitch Group and the Angle Group under vertical load (comparing the 0.8 mm pitch single-threaded implant). Decreasing rates of comprehensive relative displacement in the Compactness Group (double-threaded implant compared with the 1.6 mm pitch single-threaded implant, and the triple-threaded implant compared with the 2.4 mm-pitch single-threaded implant).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4109075&req=5

fig7: Increasing rates of comprehensive relative displacement between the Pitch Group and the Angle Group under vertical load (comparing the 0.8 mm pitch single-threaded implant). Decreasing rates of comprehensive relative displacement in the Compactness Group (double-threaded implant compared with the 1.6 mm pitch single-threaded implant, and the triple-threaded implant compared with the 2.4 mm-pitch single-threaded implant).

Mentions: We also noticed that, under vertical load and as compared with the 0.8 mm pitch single-threaded implant, the comprehensive relative displacement of the 1.6 mm pitch and 2.4 mm pitch single-threaded implants in the collar part increased by 50.75% and 53.19% in D2, 65.82% and 81.40% in D3, and 76.79% and 93.82% in D4, respectively (Figure 7). In contrast, under horizontal loading and as compared with 0.8 mm pitch single-threaded implants, the comprehensive relative displacement of 1.6 mm pitch and 2.4 mm pitch single-threaded implants in the collar part increased by 3.95% and 6.55% in D2, 26.41% and 36.00% in D3, and 27.66% and 37.97% in D4, respectively (Figure 8). Compared with the Pitch Group, a similar result in the Angle Group and the Compactness Group was observed. The findings indicate that the influence of thread pitch, helix angle, and compactness on implant stability under vertical load is more effective than under horizontal load. These results suggest that the influence of thread pitch, helix angle, and compactness on implant stability is limited in D2 but that, in D3, which had a reduction in the thickness of the cortical bone, the influence of thread pattern on implant stability was increased under horizontal load. It was originally hypothesized in this study that bone with a thicker cortical component (D2) would be more effective in providing implant stability than thread pattern. However, in D4, with a reduced trabecular bone density as compared with that in D3, there is little increase in implant micromotion under horizontal load between the two bone types. These results provide additional evidence that the density of trabecular bone has less effect on implant micromotion than the thickness of cortical bone under horizontal load. Corresponding with the results obtained in our study, some authors [54–56] also suggest that cortical bone thickness, rather than trabecular bone thickness, plays a more crucial role in implant primary stability.


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)

Increasing rates of comprehensive relative displacement between the Pitch Group and the Angle Group under vertical load (comparing the 0.8 mm pitch single-threaded implant). Decreasing rates of comprehensive relative displacement in the Compactness Group (double-threaded implant compared with the 1.6 mm pitch single-threaded implant, and the triple-threaded implant compared with the 2.4 mm-pitch single-threaded implant).
© Copyright Policy
Related In: Results  -  Collection

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

fig7: Increasing rates of comprehensive relative displacement between the Pitch Group and the Angle Group under vertical load (comparing the 0.8 mm pitch single-threaded implant). Decreasing rates of comprehensive relative displacement in the Compactness Group (double-threaded implant compared with the 1.6 mm pitch single-threaded implant, and the triple-threaded implant compared with the 2.4 mm-pitch single-threaded implant).
Mentions: We also noticed that, under vertical load and as compared with the 0.8 mm pitch single-threaded implant, the comprehensive relative displacement of the 1.6 mm pitch and 2.4 mm pitch single-threaded implants in the collar part increased by 50.75% and 53.19% in D2, 65.82% and 81.40% in D3, and 76.79% and 93.82% in D4, respectively (Figure 7). In contrast, under horizontal loading and as compared with 0.8 mm pitch single-threaded implants, the comprehensive relative displacement of 1.6 mm pitch and 2.4 mm pitch single-threaded implants in the collar part increased by 3.95% and 6.55% in D2, 26.41% and 36.00% in D3, and 27.66% and 37.97% in D4, respectively (Figure 8). Compared with the Pitch Group, a similar result in the Angle Group and the Compactness Group was observed. The findings indicate that the influence of thread pitch, helix angle, and compactness on implant stability under vertical load is more effective than under horizontal load. These results suggest that the influence of thread pitch, helix angle, and compactness on implant stability is limited in D2 but that, in D3, which had a reduction in the thickness of the cortical bone, the influence of thread pattern on implant stability was increased under horizontal load. It was originally hypothesized in this study that bone with a thicker cortical component (D2) would be more effective in providing implant stability than thread pattern. However, in D4, with a reduced trabecular bone density as compared with that in D3, there is little increase in implant micromotion under horizontal load between the two bone types. These results provide additional evidence that the density of trabecular bone has less effect on implant micromotion than the thickness of cortical bone under horizontal load. Corresponding with the results obtained in our study, some authors [54–56] also suggest that cortical bone thickness, rather than trabecular bone thickness, plays a more crucial role in implant primary stability.

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