Fig 1
Source publication
Orthodontic miniscrews are widely used as temporary anchorage devices to facilitate orthodontic movements. Miniscrew loosening is a common problem, which usually occurs during the first two weeks of treatment. Macrodesign can affect the stability of a miniscrew by changing its diameter, length, thread pitch, thread shape, tapering angle and so on....
Contexts in source publication
Context 1
... to design a dual-thread mini- screw to gain more stability encouraged us to do another FEA for the screws by the pitches equivalent half of the previous state. Figure 10 shows the stress distribution pattern of the screw when the thread pitch became equal and less than 0.45 mm. It shows that the stress distribution pattern differed from the previous state, while in this state an indirect relation between the thread pitches and maximum von Mises stresses was seen. ...
Context 2
... shows that the stress distribution pattern differed from the previous state, while in this state an indirect relation between the thread pitches and maximum von Mises stresses was seen. Figure 11 Summarizes the results of the present study. We can appreciate from the figures presented above that we can choose 0.9 and 0.45 mm thread pitches to design a dual-thread miniscrew. ...
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Introduction
Previously, a finite element (FE) model of the proximal tibia was developed and validated against experimentally measured local subchondral stiffness. This model indicated modest predictions of stiffness (R²=0.77, normalized root mean squared error (RMSE%)=16.6%). Trabecular bone though was modeled with isotropic material properties de...
Citations
... Type of the thread has a significant effect on cortical bone distributed stress [53]. The design of the implant can be optimized by using a single [54] or multiple [55], [56] threads pitch to optimize the von Misses stress distribution on cortical bone. Increasing the diameter and length of the implant decreases the stress and displacement on the implant [36], [57]- [59]. ...
Dental implants are one of the restoration methods used to revitalize the function of a lost tooth. The natural tooth has a unique structure and composition that enable it to withstand mastication loads at different rates and angles of applying load in the wet and warm environment of the mouth. To simulate such behavior, the structure, material, and design parameters (implant diameter and length, abutment connection, etc.) in dental implants are under unremitting study. A favorable dental implant should have sufficient strength and ultimate fatigue life on behalf of minimum displacement. It should be wear-resistant to keep the crown profile on the occlusal surface and remain in touch with other teeth. In this review, the effect of the usage of additive manufacturing on the quality of the 3D printed dental implant parts and important design guidelines have been studied and analyzed. Collected results are, based on finite element studies and experimental, empirical, and statistical investigations.
... The results of the assessment are presented in Tables 2-4. From the quality analysis performed, it can be concluded that 1 animal study [25] and 2 finite element analyses are at high risk of bias [27,29], and most of the in-vitro studies are at medium bias risk. Two finite element analyses and two in-vitro studies should be considered at low risk [28,30,35,39]. ...
Background:
Clinical guidelines are lacking for the use of orthodontic mini-implants (OMIs) in terms of scientific evidence referring to the choice of proper mini-design. Thus, the present study aimed to investigate to what extent orthodontic mini-implant thread design influences its stability.
Methods:
Search was conducted in five search engines on 10 May. Quality assessment was performed using study type specific scales. Whenever possible, meta-analysis was performed.
Results:
The search strategy identified 118 potential articles. Twenty papers were subjected to qualitative analysis and data from 8 papers-to meta-analysis. Studies included were characterized by high or medium quality. Four studies were considered as low quality. No clinical studies considering the number of threads, threads depth, or TSF have been found in the literature.
Conclusions:
Minidesign of OMIs seems to influence their stability in the bone. Thread pitch seems to be of special importance for OMIs retention-the more dense thread-the better stability. Thread depth seems to be of low importance for OMIs stability. There is no clear scientific evidence for optimal thread shape factor. Studies present in the literature vary greatly in study design and results reporting. Research received no external funding. Study protocol number in PROSPERO database: CRD42022340970.
... 9,10 To solve this problem non-destructive mechanical methods such as FE analysis are used. Previous research on the effect of geometry-related parameters revealed that the performance and stability of mini-implant generally affected by length, [10][11][12][13][14] screw diameter, 10,11,13 screw shape (conical or cylindrical), 12,15,16 thread shape, 4,8,13,17 screw pitch, 18 and thread depth. 13,19 Theses parameters were studied individually or in combination with two or three parameters. ...
... Similar results of the effect of screw pitch on the mini-implant stability have been reported in previous works. 18 As the thread depth increases, the miniimplant-bone contact surface increases and positively affects engagement and stability. However, the excessive increase in the thread depth leads to a reduction in the screw's internal diameter and a reduction in its shear strength against the force it applies inside the bone. ...
One of the essential aspects of the mini-implant’s successful application is its stability after being installed in the bone. The stability of the mini-implant affected the most by its geometry. In the present research, the effect of the geometry-related parameters of the mini-implant on its lateral displacement is investigated by Finite Element (FE) modeling using ABAQUS software. The parameters studied include length, diameter, pitch, and depth of the screw threads; besides, length and angle of the conical section. The Taguchi method was used to prevent many experiments. The mesh convergence tests and experimental tests confirmed the FE model quantitatively and qualitatively. Mean of means and variance analysis determined the parameters significance and their contribution on the stability. The screw diameter and length have the most contribution to mini-implant’ displacement. The effect of screw pitch was less than that for length and diameter. The conical section improved the initial stability by creating compressive stress and additional friction in its surrounding bone. No significant effects on the stability of the mini-implant have been observed for the non-threaded part. By examining the effect of thread depth on its stability by defining the ratio of thread depth to the internal diameter and to maintain the strength of the screw the optimal value for internal to external ratio is set at about 0.7.
