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The orthodontic miniscrew supported the counterclockwise rotational force in a patient with extruded upper left second molar: (a) The patient has an extruded upper left second molar (*), especially the palatal cusp. To intrude this tooth, two orthodontic miniscrews (1.8 mm in diameter, 8.5 mm in length SLA surface treated mini-implant, C-implant, CIMPLANT co., Seoul, Korea) were inserted on the buccal and palatal sides between upper left second premolar and upper left first molar. A spring was designed to apply an intruding force (black dotted arrow) on the palatal cusp of the second molar, with its wire was passing through the holes of the orthodontic miniscrews. The spring generates a counterclockwise rotational moment on the buccal orthodontic miniscrew (yellow dotted arrow); (b) Six months later, the upper left second molar was intruded successfully. Both orthodontic miniscrews stayed stable in spite of the rotational moments.
Source publication
High orthodontic forces and various directions of applied forces can be associated with loosening of the screw anchorage in the bone. Screw designs have been modified to increase the stability of the miniscrews. This research evaluates the influence of three-designs on the stability of orthodontic miniscrews. A conventionally cylinder-type miniscre...
Context in source publication
Context 1
... main result of this study that the rotational resistance of the orthodontic miniscrew with a novel design was increased would be applied to the clinical situation where the increased moment is required. Figures 9 and 10 shows an example of the counterclockwise rotational force applied to an orthodontic miniscrew. A patient with an extruded upper left second molar was treated by one of the authors (K.R.C). ...
Similar publications
This study aimed to quantify the microdamage to cortical bone of different thickness and the maximum insertion torque during orthodontic miniscrew implant (OMI) placement with and without a pilot hole. Forty-five porcine bone specimens were prepared with thicknesses of 1.5, 2 and 2.5 mm. Ten bone specimens per thickness had a pilot hole drilled pri...
Citations
... Previous studies have investigated the effect of various variables such as length, diameter, and thread features (shape, pitch, depth) on the primary stability of mini-implants in laboratory conditions [3,4,[15][16][17][18][19][20][21] or animal studies [22][23][24][25]. However, it is essential to note that the mechanical properties of artificial bone and the bone quality of animals differ from humans [10,14]. ...
Aim
There is limited research on the clinical performance of double-thread orthodontic miniscrews. This study aimed to compare the stability of double-thread and single-thread orthodontic miniscrews and identify the potential associations between patient-related and location-related factors with miniscrew stability.
Methods
This retrospective cohort study involved 90 orthodontic miniscrews (45 single-thread, 45 double-thread) with identical dimensions (8 mm length, 1.6 mm diameter). The screws were inserted in various locations within the upper jaw of 83 patients (54 females, 29 males; mean age = 15.1 ± 2.4 years). Failure was defined as excessive mobility or loss of miniscrew after placement. The data recorded were patient age, gender, insertion site, side of insertion (buccal or lingual), duration of force application, and failure occurrence.
Results
The overall success rate within the sample was 92.2%. Double-thread miniscrews exhibited a significantly higher success rate than single-thread miniscrews (P = 0.049), with 97.8% and 86.7% success rates, respectively. Gender, age, insertion location, and side of insertion did not show significant associations with failure (P > 0.05). Log-rank analysis revealed a significant difference between the two groups (P = 0.046), indicating a higher probability of survival for the double-thread design.
Conclusions
The overall success rate of orthodontic miniscrews was high in the present sample. Double-thread miniscrews placed in various locations within the maxillary arch demonstrated superior stability and survival rates compared to their single-thread counterparts. Therefore, double-thread miniscrews may be preferred when bone quality is inadequate, such as in young patients.
... Most orthodontic miniscrew stability studies have studied length, thread, diameter, and surface treatment. In the previous finite element study [54], the screw part was modified with a vertical notch at the middle of screw and a narrowed uppermost area of the screw, and the power of these screw modifications on the stability was confirmed. The new modifications of the miniscrew used in this study demonstrated the increase in stability. ...
The orthodontic miniscrew is driven into bone in a clockwise direction. Counter-clockwise rotational force applied to the implanted miniscrew can degrade the stability. The purpose of this three-dimensional finite element study was to figure out the effect of shifting the miniscrew head hole position from the long axis. Two miniscrew models were developed, one with the head hole at the long axis and the other with an eccentric hole position. One degree of counter-clockwise rotation was applied to both groups, and the maximum Von-Mises stress and moment was measured under various wire insertion angles from −60° to +60°. All Von-Mises stress and moments increased with an increase in rotational angle or wire insertion angle. The increasing slope of moment in the eccentric hole group was significantly higher than that in the centric hole group. Although the maximum Von-Mises stress was higher in the eccentric hole group, the distribution of stress was not very different from the centric hole group. As the positive wire insertion angles generated a higher moment under a counter-clockwise rotational force, it is recommended to place the head hole considering the implanting direction of the miniscrew. Clinically, multidirectional and higher forces can be applied to the miniscrew with an eccentric head hole position.
