Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Aug 9;24(1):924.
doi: 10.1186/s12903-024-04626-7.

Effects of exposure length, cortical and trabecular bone contact areas on primary stability of infrazygomatic crest mini-screws at different insertion angles

Bingran Du  1 , Yuan Lin  1 , Mohan Ji  2 , Qiaohua Yang  3 , Jiang Jiang  4 , Fei Wang  4   5 , Xiaoyi Wang  6 , Jinchuan Tan  4 , Rui Jia  4   7 , Jianyi Li  8
Affiliations

Effects of exposure length, cortical and trabecular bone contact areas on primary stability of infrazygomatic crest mini-screws at different insertion angles

Bingran Du et al. BMC Oral Health. .

Abstract

Background: The infrazygomatic crest mini-screw has been widely used, but the biomechanical performance of mini-screws at different insertion angles is still uncertain. The aim of this study was to analyse the primary stability of infrazygomatic crest mini-screws at different angles and to explore the effects of the exposure length (EL), screw-cortical bone contact area (SCA), and screw-trabecular bone contact area (STA) on this primary stability.

Methods: Ninety synthetic bones were assigned to nine groups to insert mini-screws at the cross-combined angles in the occlusogingival and mesiodistal directions. SCA, STA, EL, and lateral pull-out strength (LPS) were measured, and their relationships were analysed. Twelve mini-screws were then inserted at the optimal and poor angulations into the maxillae from six fresh cadaver heads, and the same biomechanical metrics were measured for validation.

Results: In the synthetic-bone test, the LPS, SCA, STA, and EL had significant correlations with the angle in the occlusogingival direction (rLPS = 0.886, rSCA = -0.946, rSTA = 0.911, and rEL= -0.731; all P < 0.001). In the cadaver-validation test, significant differences were noted in the LPS (P = 0.011), SCA (P = 0.020), STA (P = 0.004), and EL (P = 0.001) between the poor and optimal angulations in the occlusogingival direction. The STA had positive correlations with LPS (rs = 0.245 [synthetic-bone test] and r = 0.720 [cadaver-validation test]; both P < 0.05).

Conclusions: The primary stability of the infrazygomatic crest mini-screw was correlated with occlusogingival angulations. The STA significantly affected the primary stability of the infrazygomatic crest mini-screw, but the SCA and EL did not.

Keywords: Bone; Insertion angles; Mini-screws; Stability.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
The insertion of the infrazygomatic crest mini-screw. (a) Customised guide plate for mini-screw insertion. (b) Nine groups with different combinations of the occlusogingival and mesiodistal angles. (c) The mini-screw was inserted until the beginning of the non-threaded part contacted the bone surface. MD mesial direction; DD distal direction; GD gingival direction; OD occlusal direction
Fig. 2
Fig. 2
Measurement of the actual insertion angle of the mini-screw. (a) The 3D models obtained using SmartScan. (b) Measurement of the actual insertion angle of the mini-screw. Angle MD actual insertion angle of the mini-screw in the mesiodistal direction; Angle OG actual insertion angle of the mini-screw in the occlusogingival direction; Line MD the projection of the insertion path on the mesiodistal plane (MDP); Line OG the projection of the insertion path on the occlusogingival plane (OGP)
Fig. 3
Fig. 3
Measurement of the SCA, STA, and EL of the mini-screw. (a) The rendering of the two models after registration. blue model, the 3D model of screw-bone block; grey model, the 3D model of the mini-screw. (b) Measurement of the SCA and STA; blue area, STA; red area, SCA. (c) Measurement of EL; black point, the insertion site; green point, the apex of the mini-screw cap. SCA screw-cortical bone contact area; STA screw-trabecular bone contact area; EL exposure length
Fig. 4
Fig. 4
Lateral pull-out testing for the infrazygomatic crest mini-screw. (a) The mechanical testing machine for testing. (b) The pull-out grip and bone fixing device. (c) The procedure of lateral pull-out testing. MD mesial direction; DD distal direction; GD gingival direction; OD occlusal direction
Fig. 5
Fig. 5
The digital model of screw-maxilla specimen. (a) Reconstruction of the maxilla specimen based on µCT images. (b) The insertion of mini-screws with the help of a guide plate (white model). (c) The scanning model of screw-maxilla specimen
Fig. 6
Fig. 6
An image of lateral pull-out testing. MD mesial direction; DD distal direction; GD gingival direction; OD occlusal direction
Fig. 7
Fig. 7
The differences between the optimal and poor angulations in cadaver-validation testing. (a) The difference in the LPS. (b) The difference in the SCA. (c) The difference in the STA. (d) The difference in the EL. LPS lateral pull-out strength; SCA screw-cortical bone contact area; STA screw-trabecular bone contact area; EL exposure length
See this image and copyright information in PMC

References

    1. Liou EJW, Chen P, Wang Y, Lin JC. A computed Tomographic Image Study on the thickness of the Infrazygomatic Crest of the Maxilla and its clinical implications for Miniscrew insertion. Am J Orthod Dentofac Orthop. 2007;131:352–6. 10.1016/j.ajodo.2005.04.044.10.1016/j.ajodo.2005.04.044 - DOI - PubMed
    1. Chen Y, Kao C, Huang T. Evaluation of ten Extra-alveolar Temporary Anchorage device insertion sites by Cone Beam Volumetric Computer Tomography: a pilot study. J Dent Sci. 2010;5:21–9. 10.1016/S1991-7902(10)60004-9.10.1016/S1991-7902(10)60004-9 - DOI
    1. Jia X, Chen X, Huang X. Influence of Orthodontic Mini-implant Penetration of the Maxillary Sinus in the Infrazygomatic Crest Region. Am J Orthod Dentofac Orthop. 2018;153:656–61. 10.1016/j.ajodo.2017.08.021.10.1016/j.ajodo.2017.08.021 - DOI - PubMed
    1. Nienkemper M, Handschel J, Drescher D. Systematic review of Mini-implant Displacement under Orthodontic Loading. Int J Oral Sci. 2014;6:1–6. 10.1038/ijos.2013.92. 10.1038/ijos.2013.92 - DOI - PMC - PubMed
    1. Miyawaki S, Koyama I, Inoue M, Mishima K, Sugahara T, Takano-Yamamoto T. Factors Associated with the Stability of Titanium screws placed in the posterior region for Orthodontic Anchorage. Am J Orthod Dentofac Orthop. 2003;124:373–8. 10.1016/s0889-5406(03)00565-1.10.1016/s0889-5406(03)00565-1 - DOI - PubMed

MeSH terms

LinkOut - more resources