Stability Of Orthodontic Miniscrews Research Articles

Low-Level Light Therapy in Orthodontic Treatment: A Systematic Review

This current review aims to provide an overview of the most recent research from the last 10 years on the potential of low-level light therapy (LLLT) in the orthodontic field, particularly focusing on studies about tooth movement, root resorption, pain perception during treatment, and the stability of orthodontic miniscrews. “Low-level laser,” “orthodontic,” and “LLLT” were the search terms utilized on the databases Scopus, Web of Science, and PubMed, and the Boolean operator “AND” was utilized. Of the 974 studies found, 41 publications related to our topic were included in this review. Many authors agree that LLLT could trigger an enhanced biological reaction next to the tooth in the periodontium, promoting osteoblast proliferation and differentiation, while it could also have a positive impact on bone regeneration and on increasing the rate of tooth movement, enhancing the stability of miniscrews and minimizing the occurrence of root resorption. Regarding pain management during treatment studies, the results have been controversial. Conclusions: even though further studies are still needed, the use of LLLT can improve both clinical results and patient comfort during treatment by reducing treatment duration, improving clinical aspects, such as miniscrew stability, and minimizing root resorption. Further investigations are needed to assess whether LLLT offers any real benefits regarding pain relief.

STABILITY OF ORTHODONTIC MINI-SCREWS AND DIFFERENT EXPERIENCE LEVELS OF RESIDENCY TRAINING OF STUDENTS

Objectives: To determine the association between the stability of orthodontic mini-screws with different experience levels of residency training of students. Materials and methods: A total of 240 mini-screws with a diameter of 1.3 mm, and a length of 7 mm were inserted by orthodontic residents in the first, second, third, and fourth years. Stability was assessed after one month of application of orthodontic load. Chi-square tests were used to analyze data. P value ?.05 was considered significant. Results: Out of 240 implants, 172 were found to be stable and 68 were unstable after one month among different resident levels. There was a significant association between the stability of mini-screws and different experience levels of postgraduate residents. For first-year residents, stability was 53.8%, for second-year residents 27.3%, for the third year 93.3%, and the fourth year 90.5%. The association between the placement site of mini-screws and different levels of postgraduate residents was also significant and the highest number of stable mini-screws were found in maxilla and posterior mandible placed by fourth-year residents, and the least stable for second-year residents. Conclusion: The experience level of residents is a significant factor in the stability of mini-screws and site-specific stability is higher in the maxilla and posterior mandible for fourth-year residents. Key Words: Anchorage, Insertion site, Maxilla, Mandible, Orthodontists, Stability, Temporary Anchorage Devices (TADs).

Bone quality affects stability of orthodontic miniscrews

The objective of this study was to evaluate the effect of bone–miniscrew contact percentage (BMC%) and bone quality and quantity on orthodontic miniscrew stability and the maximum insertion torque value (ITV). Orthodontic miniscrews of five different dimensions and several bovine iliac bone specimens were used in the evaluation. Miniscrews of each dimension group were inserted into 20 positions in bovine iliac bone specimens. The experiment was divided into three parts: (1) Bone quality and quantity were evaluated using cone-beam computed tomography (CBCT) and microcomputed tomography. (2) The 3D BMC% was calculated. (3) The ITVs during miniscrew insertion were recorded to evaluate the stability of the orthodontic miniscrews. The results indicated that longer and thicker miniscrews enabled higher ITVs. CBCT was used to accurately measure cortical bone thickness (r = 0.939, P < 0.05) and to predict the bone volume fraction of cancellous bone (r = 0.752, P < 0.05). BMC% was significantly influenced by miniscrew length. The contribution of cortical bone thickness to the ITV is greater than that of cancellous bone structure, and the contribution of cortical bone thickness to BMC% is greater than that of cancellous bone structure. Finally, the higher is BMC%, the greater is the ITV. This study concludes that use of CBCT may predict the mechanical stability of orthodontic miniscrews.

Effectiveness of Photobiomodulation on Orthodontic Mini Screw Stability: A Systematic Review.

Objective: Photobiomodulation therapy (PBMT) enhances bone regeneration and bone healing and has been suggested to improve the stability of orthodontic mini screws. This study aimed to systematically review the clinical influence of PBMT on orthodontic mini screw stability. Methods: A comprehensive search was run in the following electronic databases: PubMed, EMBASE, Web of Science, Scopus, and Cochrane. The clinical trials reporting the effects of PBMT on mini screw stability in human subjects were included. Two reviewers independently screened and extracted data. The Cochrane Risk of Bias Assessment Tool was used to investigate the quality of the included studies. The overall quality of evidence was evaluated through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. The primary outcome was the stability of mini screws, and the secondary outcomes were pain, inflammation [the interleukin (IL)-1ß, IL6, and IL8], and overall success rate. Quantitative synthesis could not be performed due to heterogeneities among studies. Results: Seven articles were finally included in the present review. Moderate-quality evidence suggests that if the PBMT continues until the third or fourth week, the stability of min screws would be promoted from the third to the eighth week after insertion. Although the evidence for secondary outcomes was limited, PBMT could positively affect the inflammation. Conclusions: PBMT exerted varying effects on the stability of mini screws at different time intervals. However, despite the limitations of studies, it seems to enhance the secondary stability of orthodontic mini screws primarily. Registration: The study protocol was registered on PROSPERO (https://www.crd.york.ac.uk/PROSPERO/) with the ID#CRD42020194058.

Effect of Different Head Hole Position on the Rotational Resistance and Stability of Orthodontic Miniscrews: A Three-Dimensional Finite Element Study.

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.

Effect of Different Surface Designs on the Rotational Resistance and Stability of Orthodontic Miniscrews: A Three-Dimensional Finite Element Study.

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 miniscrew design (Bio-Action screw, Jin-Biomed co., Bucheon, Korea) was set as a control, and three conditions were studied based on modifications of this control design. Condition-1 has narrowed threads in the upper part of the screw; Condition-2 has a notch at the middle part; and Condition-3 has the combination of Condition-1 and Condition-2. The moment required to unwind the miniscrew to five degrees is tested, and the moment generated at the cortical bone and the trabecular bone were calculated with finite element analysis. Compared to the control, all three conditions showed a higher moment required to unwind the miniscrew and a higher moment generated at the cortical bone. At the trabecular bone, condition-2 and -3 showed higher moment than the control, and condition-1 showed similar moment to the control. Condition-3 required a higher overall moment to unwind the miniscrew. These findings validate the design modifications used to increase the rotational resistance.

Factors affecting primary stability of orthodontic miniscrews: a literature review

Factors affecting primary stability of orthodontic miniscrews: a literature review

Histomorphometric evaluation of the effects of various diode lasers and force levels on orthodontic mini screw stability.

The purpose of this study was to evaluate the effects of different laser dose and force levels on the stability of orthodontic mini screws used for anchorage, by histomorphometric analyses. Low-level laser therapy speeds up blood flow, improves the mechanism of the revitalization processes, reduces the risk of infection, boosts metabolic activities, and accelerates the healing of the damaged tissue. Although there are many research studies about low-level laser therapy applications in a variety of areas, no investigations were found concerning mini screw stability using various laser dose levels with different force level applications. Seventeen New Zealand white rabbits were used. A total of 68 cylindrical, self-drilling orthodontic mini screws were threaded at the fibula. Experimental subjects were divided into six groups; force application was not performed in the first three groups, whereas 150 g of force was applied via nickel-titanium closed-coil springs placed between two mini screws in the other three groups. Measurements of the initial torque values (10 Ncm) were manipulated by a digital portable torque gauge. Various low-level laser doses were applied to the groups during the postoperative 10 days. After 4 weeks, bone-to-implant contact and cortical bone thickness were histomorphometrically analyzed. In the 150 g force plus 20 J/cm(2) dosage group, the highest bone-to-implant contact values were observed. (p<0.05) There were no statistically significant correlations between cortical bone thickness and bone-to-implant contact values; on the other hand, no significant difference was found among the same groups in terms of cortical bone thickness values (p>0.05). Low-level laser therapy was noticed to induce the mini screw-bone contact area. Low-level laser therapy may be a supplementary treatment method to increase the stability of the orthodontic mini screw.

A preliminary study of the effects of low-intensity pulsed ultrasound exposure on the stability of orthodontic miniscrews in growing rats

Orthodontic miniscrews placed in growing subjects often loosen during orthodontic treatment. The ability to place miniscrews, regardless of age, would be clinically beneficial. To assess the effects of low-intensity pulsed ultrasound (LIPUS) on the stability of orthodontic miniscrews in growing rats. The mobility of miniscrews after placement was recorded and the miniscrew-bone interface was examined histomorphometrically using tibiae of seven male Sprague-Dawley rats (aged 6 weeks). Field-emission scanning electron microscopic images were used to evaluate the bone-miniscrew interface, and a mobility test device was used to assess the stiffness of miniscrew placement. Fourteen custom-made miniscrews with 1.4mm diameters and 4.0mm lengths were placed in the right and left tibiae. LIPUS was used to stimulate right tibiae at the sites of miniscrew placement, and left tibiae were left untreated as controls. Significantly lower mobility was observed in the LIPUS-treated group compared with the control group (P < 0.05). Histomorphometric evaluation indicated that bone-miniscrew adhesion was significantly better in the LIPUS-treated group than in the control group (P < 0.05). This in vivo study used tibiae rather than jaw bones because the jaw bones of 6-week-old rats were too small to allow miniscrew placement. LIPUS was able to increase the bone-miniscrew contact and reduce the mobility of miniscrews in growing subjects. LIPUS may accelerate the bone healing process after miniscrew placement in growing subjects and can reduce the latent period.

Influence of the thickness of cortical bone on the stability of orthodontic miniscrews

Three 10-mm-long miniscrews commonly employed in orthodontic treatment were compared in four different situations involving diverse thicknesses of cortical bone. The finite element method (FEM) was used in the study, in which a force of 250 g was applied in two directions: perpendicular and parallel to the bone surface. As the parameter under study was the thickness of cortical bone, simulations were performed in four different bone loss situations: 2.5, 2, 1.5 and 1 mm. Our aim was also to quantify the stresses and displacements generated when applying a force of 250 g perpendicular and parallel to the bone surface under the same skeletal conditions. The results reveal similar performance in the three analysed samples, with increased stresses and displacements in the surrounding bone in relation to similar variations in the thickness of cortical bone.

Effects of repeated sterilization cycles on primary stability of orthodontic mini-screws

To determine if repeated sterilization has deleterious effects on the clinical stability of mini-screws. Thirty each of the following mini-screws were tested: Aarhus (American Orthodontics, Sheboygan, Wisc), VectorTAS (Ormco Corporation, Orange, Calif), Dual-Top (RMO, Denver, Colo), and Ortho Anchor (KLS Martin, Jacksonville, Fla). Controls were sterilized once using a steam autoclave (Statim 5000, SciCan USA, Canonsburg, Pa). Each group of mini-screws was divided into three groups: the control (n = 10) and two test groups (n =10, each). Test groups were cycled five and 10 times respectively. All screws were inserted into custom-designed synthetic blocks that simulated mandibular bone. Maximum insertion torque and lateral displacement force data were recorded and subjected to statistical testing. Two-way analysis of variance (ANOVA) and three-way mixed ANOVA were used for statistical analyses for maximum insertion torque data and lateral displacement force data, respectively. Level of significance was established at P < .05. Insertion torque values displayed significant differences between both of the groups and sterilization cycles (P < .05). Significant differences were observed between American Aarhus mini-screws and both RMO and KLS Martin mini-screws. Ormco Vector mini-screws also differed significantly from the KLS Martin mini-screws in this comparison (P < .05). For lateral displacement, there was a significant main effect of groups, F(1,36) = 14.5 (P < .05). Significant differences were observed between American Aarhus mini-screws and all three of the other groups (P < .05). The examined groups displayed statistical differences of variable quality that may not affect their clinical stability.

Effects of placement angle and direction of orthopedic force application on the stability of orthodontic miniscrews

To evaluate the influence of placement angle and direction of orthopedic force application on the stability of miniscrews. Finite element analysis was performed using miniscrews inserted into supporting bone at angles of 90°, 60°, and 30° (P90°, P60°, and P30°). An orthopedic heavy force of 800 gf was applied to the heads of the miniscrews in four upward (U0°, U30°, U60°, U90°) or lateral (L0°, L30°, L60°, L90°) directions. In addition, pull-out strength of the miniscrews was measured with various force directions and cortical bone thicknesses. Miniscrews with a placement angle of 30° (P30°) and 60° (P60°) showed a significant increase in maximum von Mises stress following the increase in lateral force vectors (U30°, U60°, U90°) compared to those with a placement angle of 90° (P90°). In accordance, the pull-out strength was higher with the axial upward force when compared to the upward force with lateral vectors. Maximum von Mises stress and displacement of the miniscrew increased as the angle of lateral force increased (L30°, L60°, L90°). However, a more dramatic increase in maximum von Mises stress was noted in P30° than in P60° and P90°. Placement of the miniscrew perpendicular to the cortical bone is advantageous in terms of biomechanical stability. Placement angles of less than 60° can reduce the stability of miniscrews when orthopedic forces are applied in various directions.