Primary Stability of Orthodontic Titanium Miniscrews due to Cortical Bone Density and Re-Insertion

Current situation, trends, and challenges navigating temporary anchorage devices usage among orthodontists in China: a comprehensive multi-center survey

BACKGROUND

The temporary anchorage devices (TADs) are presently a viable and popular treatment option for orthodontics all over the world. However, there is a lack of investigation and research on its application among orthodontists in China. This study aims to explore factors influencing temporary anchorage devices usage and compare current perspectives and usage patterns between orthodontic specialists and general dentists, thereby establishing new consensus and guiding future improvements.

METHODS

A cross-sectional study using a multi-center structured questionnaire was designed. The Chi-square test, Mann-Whitney U test, and logistic regression were performed.

RESULTS

Respondents were from 30 provincial-level regions. Most doctors had relatively rich clinical experience in orthodontics, with 65.70% working for over 10 years. Respondents reported a relatively high usage rate (87.54%) and satisfaction with TADs (93.85%). The analysis result showed Chinese orthodontists who received more TADs training (P < 0.01), had higher educational attainment (P < 0.01), and used more clear aligners (P < 0.01) tended to use TADs more frequently. About 95.90% of respondents believed TADs helped achieve higher treatment goals, 68.23% agreed they could shorten treatment duration, and 51.82% believed they reduced the probability of orthodontic-orthognathic treatment. Differences in the understanding of indications for TADs, improvement method of TADs can be observed between orthodontic specialists and general dentists (P < 0.05).

CONCLUSIONS

Chinese orthodontists were relatively active in using TADs. The factors most closely associated with TAD usage included related training, the type of orthodontic appliances used and the highest educational attainment. Orthodontic specialists and general dentists might had differing perspectives regarding TADs, but they tended to follow similar management procedures.

Development and in vitro testing of an orthodontic miniscrew for use in the mandible

OBJECTIVE

Temporary anchorage devices (TADs) have been successfully used in the maxilla. However, in the mandible, lower success rates present a challenge in everyday clinical practice. A new TAD design will be presented that is intended to demonstrate optimization of the coupling structure as well as in the thread area for use in the mandible.

METHODS

Three TADs were examined: (A) Aarhus® system (68.99.33 A, Medicon, Tuttlingen, Germany), (B) BENEfit® orthodontic screw (ST-33-54209; PSM Medical, Gunningen, Germany) and (C) a new design with a two-part screw thread. The TADs were inserted into artificial bone blocks after predrilling to test primary stability. To test the fracture stability, the TADs were embedded in Technovit® 4004 (Heraeus Kulzer, Wehrheim, Germany) and torsional loaded at an angle of 90° until fracture. The threshold torque values occurring were recorded digitally. The statistical evaluation was carried out using the Kruskal-Wallis test with a post hoc test according to Bonferroni (p < 0.05).

RESULTS

The following values were measured for the insertion torque: A: 33.7 ± 3.3 Ncm; B: 57.1 ± 8.4 Ncm; C: 34.2 ± 1.4 Ncm. There were significant differences between A-B and B-C. The measured values for the fracture strength were as follows: A: 46.7 ± 3.5 Ncm; B: 64.2 ± 5.1 Ncm; C: 55.4 ± 5.1 Ncm. Significant differences were found between all groups.

CONCLUSION

The adapted screw design has no negative influence on primary and fracture stability. Whether the design has a positive effect on the success rates in the mandible must be clarified in further clinical studies.

The Interrelation between Cortical Bone Thickness and Primary and Secondary Dental Implant Stability: a Systematic Review

Objectives

Dental implants have emerged as a reliable and long-lasting solution for missing teeth, offering advantages over traditional prosthetic options. The aim of this systematic review was to thoroughly explore the correlation between cortical bone thickness of the jaws and bone-level dental implant primary and secondary stability.

Material and Methods

A comprehensive literature search was conducted in MEDLINE (PubMed), ClinicalKey and the Cochrane Library from 1 January, 2019 to 21 June, 2024. This review focused on patients undergoing dental implant placement with varying cortical bone thicknesses and implant stability levels. Quality and risk-of-bias assessment evaluated by Cochrane risk of bias tool.

Results

Out of 160 screened articles, 28 were reviewed in full, and 6 met the inclusion criteria, involving 209 patients and 418 implants. Implant stability quotient (ISQ) values showed no significant correlations during baseline and secondary assessments (P > 0.05). Correlations were noted between implant stability, bone density, alveolar ridge width, and implant size (P < 0.01). ISQ and insertion torque value (ITV) were strongly correlated at insertion (P < 0.001) but not at follow-ups (P = 0.059 at 2 months, P = 0.817 at 6 months, P = 0.029 at 12 months). ISQ values increased over time (P < 0.001). Implants in native bone showed higher ISQ values at baseline (P = 0.011), 8 weeks (P = 0.013), and 12 weeks (P < 0.001). Regions with thicker cortical bone demonstrated superior primary stability.

Conclusions

Thicker cortical bone enhances primary implant stability, as indicated by higher insertion torque and implant stability quotient values.

Stress distribution for mandibular extra-alveolar anchorage at different angles and force magnitudes: a finite element study

The aim of this study was to evaluate the stress distribution in cortical and cancellous bones and within the screw when a stainless steel extra-alveolar screw (EA-S) is inserted into the retromolar region of the mandible using the finite element method (FEM). The stress values in the EA-S were highest at 60° with horizontal (shear) force and lowest at 90° with axial force. In the bones (cortical and cancellous), the stress value was greatest at 90° with horizontal force. Greater stability of the screw may be achieved by tilting it to the force when horizontal loads are applied.

The Influence of the Diameter of Orthodontic Mini-Implants on Primary Stability: Bending Tests-An In Vitro Study

Orthodontic Mini-Implants have a high success rate, but it is crucial to assess the load that they bear in order to maintain their primary stability. Increasing the diameter can improve this stability, but there are limitations due to the proximity of the tooth roots. To avoid damage, smaller diameters are used, which can decrease resistance and cause permanent deformations.

OBJECTIVE

The objective of this study is to evaluate the influence of the diameter of Mini-Implants through bending force tests, taking into account primary stability after one and two insertions.

METHODS

Here, 40 Ti6AI4V alloy Mini-Implants of two different brands and diameters were divided into eight groups, half of which received one insertion in the artificial bone, and the rest received two. All were subjected to a constant bending force using an INSTRON-Electropuls E10000LT (Norwood, MA, USA) until fracture.

RESULTS

The smaller-diameter Mini-Implants were less resistant to fracture, but both were able to withstand the necessary loads produced by orthodontic movements. As for the inserts, there were no statistically significant differences.

CONCLUSIONS

There is an advantage to using 1.6 mm Mini-Implants over 2.0 mm ones, as a smaller diameter does not lead to fracture due to the forces used in orthodontic treatment. Having one or two inserts did not have a statistically significant effect.

Evaluation of Effect of Different Insertion Speeds and Torques on Implant Placement Condition and Removal Torque in Polyurethane Dense D1 Bone Model

The aim of this study was to evaluate the effect of two different insertion speeds at eight different insertion torque values ranging from 25 to 60 during implantation in a dense polyurethane (PU) D1 bone model on the placement condition and removal torque of dental implants. In this study, 50 pcf single-layer PU plates were used. In the study, a total of 320 implant sockets were divided into two groups, Group 1 (30 rpm) and Group 2 (50 rpm), in terms of insertion speed. Group 1 and Group 2 were divided into eight subgroups with 25, 30, 35, 40, 45, 50, 55 and 60 torques. There were 20 implant sockets in each subgroup. During the implantations, the implant placement condition and removal torque values were assessed. There was a statistically significant difference between the 30 and 50 rpm groups in terms of overall implant placement condition (p < 0.01). It was found that the removal torque values at 50 rpm were statistically significantly higher than those at 30 rpm (p < 0.01). This study showed that in dense D1 bone, the minimum parameters at which all implants could be placed at the bone level were 50 torque at 30 rpm and 40 torque at 50 rpm.

The effect of different orthodontic mini-implant brands and geometry on primary stability (an in vitro study)

Background

In orthodontic procedures, mini-implants are routinely used as temporary anchorage devices. Early failure is primarily attributed to a variety of issues, which are mostly connected to the quality and geometry of the screw that lead to insufficient primary stability.

Objectives

To evaluate the primary stability of different sizes and brands of orthodontic mini-implants by optimizing the insertion torque value (ITV) and to clear out which one has the greatest primary stability among the most widely used mini-implants by orthodontists.

Methods

Eighty-two self-drilling mini-implants from three different brands with different sizes were used (Optimus Ortho System (Osteonic made in Korea), Smart anchor (GNI made in Korea) (1.4 × 6, 1.6 × 8 and 1.8 × 10mm) and Morelli (made in Brazil) (1.5 × 6, 1.5 × 8 and 1.5 × 10mm), made from (Ti 6Al 4V). All were drilled at a 60° angle on Sixty artificial bone blocks made from polyurethane foam with a digital torque meter device (Orthonia, Jeil made in Korea), pullout strength (tensile force) was measured with a universal testing machine to find out the best brand and size in the mean of primary stability. Data were analyzed using SPSS Version 25 and JMP Pro Version 16 software using the One-way ANOVA test, the Post hoc and Tukey HCD tests.

Results

There were significant differences between the pullout strength of different sizes for the GNI and OSTEONIC brands, while for the MORELLI brand there were no significant differences between the three different sizes considering ITV (10Ncm) whereas for ITV (20Ncm) there was a significant difference between the different sizes for the pullout of all three brands. GNI was the best brand for all the selected sizes with ITV (10Ncm) and size 1.4 × 6 for ITV (20Ncm), whereas OSTEONIC sizes 1.6 × 8 and 1.8 × 10 were the best for ITV (20Ncm) in term of primary stability.

Conclusion

GNI screws were demonstrated higher primary among the three widely used brands followed by OSTEONIC for size 1.6 × 8 and 1.8 × 10 while MORELLI was the least resistant to dislodgement for the two torque insertion values 10 N/cm and 20 N/cm.

Effects of Intrabony Length and Cortical Bone Density on the Primary Stability of Orthodontic Miniscrews

Miniscrews have gained recent popularity as temporary anchorage devices in orthodontic treatments, where failure due to sinus perforations or damage to the neighboring roots have increased. Issues regarding miniscrews in insufficient interradicular space must also be resolved. This study aimed to evaluate the primary stability of miniscrews shorter than 6 mm and their feasibility in artificial bone with densities of 30, 40, and 50 pounds per cubic foot (pcf). The primary stability was evaluated by adjusting the intrabony miniscrew length, based on several physical properties: maximum insertion torque (MIT), maximum removal torque (MRT), removal angular momentum (RAM), horizontal resistance, and micromotion. The MIT and micromotion results demonstrated that the intrabony length of a miniscrew significantly affected its stability in low-density cortical bone, unlike cases with a higher cortical bone density (p < 0.05). The horizontal resistance, MRT, and RAM were affected by the intrabony length, regardless of the bone density (p < 0.05). Thus, the primary stability of miniscrews was affected by both the cortical bone density and intrabony length. The effect of the intrabony length was more significant in low-density cortical bone, where the implantation depth increased as more energy was required to remove the miniscrew. This facilitated higher resistance and a lower risk of falling out.