Evaluation of the effects of different surface configurations on stability of miniscrews

Success rates of single-thread and double-thread orthodontic miniscrews in the maxillary arch

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.

Effect of thread depth and thread pitch on the primary stability of miniscrews receiving a torque load : A finite element analysis

PURPOSE

We have been developing a new type of miniscrew to specifically withstand orthodontic torque load. This study aimed to investigate the effect of thread depth and thread pitch on the primary stability of these miniscrews if stressed with torque load.

METHODS

Finite element analysis (FEA) was used to evaluate the primary stability of the miniscrews. For thread depth analysis, the thread depth was set to 0.1-0.4 mm to construct 7 models. For thread pitch analysis, the thread pitch was set to 0.4-1.0 mm to construct another 7 models. A torque load of 6 Nmm was applied to the miniscrew, and the other parameters were kept constant for the analyses. Maximum equivalent stress (Max EQV) of cortical bone and maximum displacement of the miniscrews (Max DM) were the indicators for primary stability of the miniscrew in the 14 models.

RESULTS

In the thread depth analysis, Max DM increased as the miniscrew thread depth increased, while Max EQV was smallest in model 3 (thread depth = 0.2, Max EQV = 8.91 MPa). In the pitch analysis, with an increase of the thread pitch, Max DM generally exhibited a trend to increase, while Max EQV of cortical bone showed a general trend to decrease.

CONCLUSION

Considering the data of Max DM and Max EQV, the most appropriate thread depth and thread pitch of the miniscrews in our model was 0.2 and 0.7 mm, respectively. This knowledge may effectively improve the primary stability of newly developed miniscrews.

A novel auxiliary device enhances miniscrew stability under immediate heavy loading simulating orthopedic treatment

OBJECTIVES

To evaluate miniscrew stability and perform a histomorphometric analysis of the bone around the miniscrew under a load corresponding to orthopedic force.

MATERIALS AND METHODS

Thirty-two miniscrews were implanted into eight rabbit tibias. Auxiliary group rabbits received auxiliary devices with miniscrews (n = 8, 28 days; n = 8, 56 days), and those in the nonauxiliary control group received miniscrews without auxiliary devices (n = 8, 28 days; n = 8, 56 days). Elastics were placed between miniscrews to apply a load of 5 N. Miniscrew stability was evaluated using a Periotest. Bone-to-implant contact (BIC) and spike implantation depth were measured histomorphologically.

RESULTS

Periotest values in the auxiliary group were significantly lower than those in the nonauxiliary group at all time periods. There was no significant difference in BIC between the auxiliary and nonauxiliary groups at 28 or 56 days postimplantation. The implantation spike depth in the auxiliary group was significantly greater at 56 days compared to that at 28 days. Newly formed bone was observed around the spike of the auxiliary device at 56 days.

CONCLUSIONS

The results suggest that the use of miniscrews in conjunction with auxiliary devices provides stable skeletal anchorage, which may be useful in orthopedic treatments.

How Does Orthodontic Mini-Implant Thread Minidesign Influence the Stability?-Systematic Review with Meta-Analysis

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.

The antimicrobial effect of doxycycline and doped ZnO in TiO2 nanotubes synthesized on the surface of orthodontic mini-implants

Objectives:

Anchorage preservation is crucial in orthodontic treatment success. Mini-implants make a revolution in this domain. The failure of orthodontic mini-implants due to inflammation and infection is one of the reasons for anchorage loss. The purpose of this study was to evaluate the effect of a novel mini-implant surface modification to improve resistance against microbial contamination and surrounding tissue inflammation.

Material and Methods:

Twenty-four orthodontic mini-implants (Jeil Medical Corporation, Korea) with 1.6 mm diameter and 8 mm length were randomly divided into three groups: Group 1: Control group, Group 2: Nanotubes were made on the surface with anodisation, and Group 3: Zinc Oxide (ZnO) doped into nanotubes, and then doxycycline is added to them. The anti-bacterial efficacy against Porphyromonas gingivalis was evaluated using the disk diffusion method. To analyze data, Kruskal–Wallis, Friedman, and Wilcoxon tests were done. The significance level was set at 0.05.

Results:

No zone of the inhibition was formed in Groups 1 and 2. In Group 3, the mean (SD) diameter of the inhibition zone in the first 5-day to sixth 5-day were 38.7(8.2), 25(4.8), 17.8(5.6), 7.63(5.37), 1.5(2.83), and 0 millimeters, respectively.

Conclusion:

Nanotubes containing doped ZnO and Doxycycline are capable of preventing bacterial growth around the mini implant surfaces for at least up to 30 days. To manage inflammation of surrounding tissues of mini-implants, nanotubes are not effective alone. Therefore, the presence of diffusible materials in addition to nanotubes on the surface of mini-implants is necessary.

Optimization Analysis of Two-Factor Continuous Variable between Thread Depth and Pitch of Microimplant under Toque Force

Microimplant, an anchorage device, is widely applied in clinical orthodontic treatment. Since tooth torque is required to be controlled during orthodontic tooth movement, a novel microimplant needs to be developed to apply better torque force during orthodontic. In this study, the optimal value ranges of thread depth and pitch under toque force were studied for choosing microimplant with relevant value ranges in clinical design from biomechanical perspective. Finite element analysis (FEA) and optimization design technology were used for accessing the optimal value ranges of thread depth and pitch under toque force. Thread depth (D) (0.1 mm to 0.4 mm) and pitch (P) (0.4 mm to 1 mm) were used as continuous variables, with the other parameters as constant, and the optimal value ranges were obtained by analyzing the tangent slope and sensitivity of the response curve. When a torque force of 6 Nmm was applied on the microimplant, the maximum equivalent stress (Max EQV) of cortical bone and maximum displacements (Max DM) of microimplant were analysis indexes. When 0.55 mm ≤ P ≤ 1 mm, the Max EQV of cortical bone was relatively smaller with less variation range. When 0.1 mm ≤ D ≤ 0.35 mm, the Max DM of microimplant was relatively smaller with less variation range. So in conclusion, the initial stability of microimplants with pitch 0.55 mm ≤ P ≤ 1 mm and thread depth 0.1 mm ≤ D ≤ 0.35 mm was better with the torque force applied.

Clinical and Radiological Outcomes for Guided Implant Placement in Sites Preserved with Bioactive Glass Bone Graft after Tooth Extraction: A Controlled Clinical Trial

The goal of the study was to evaluate marginal bone loss (MBL) after 1-year implant placement using a guided implant surgical (GIS) protocol in grafted sockets compared to non-grafted sites. We followed a parallel study design with patients divided into two groups: grafted group (Test group, n = 10) and non-grafted group (Control, n = 10). A bioactive glass bone graft was used for grafting. A single edentulous site with a minimum bone height ≥11 mm and bone width ≥6 mm confirmed by cone-beam computerized tomography (CBCT) was chosen for implant placement. Tapered hybrid implants that were sandblasted and acid-etched (HSA) were placed using the GIS protocol and immediately loaded with a provisional prosthesis. MBL and implant survival rates (ISR) were assessed based on standardized radiographs and clinical exams. Patients were followed up for 1-year post-loading. MBL after one year, in the control group, was −0.31 ± 0.11 mm (mesial) and −0.28 ± 0.09 mm (distal); and in the test group was −0.35 ± 0.11 mm (mesial) and −0.33 ± 0.13 mm (distal), with no statistical significance (p > 0.05). ISR was 100% in both groups after one year. ISR was similar between groups and the marginal bone changes were comparable one year after functional loading, without statistical significance, suggesting that bioactive glass permitted adequate bone formation. The GIS protocol avoided raising flaps and provided a better position to place implants, preserving the marginal bone around implants.

Mini implants osseointegration, molar intrusion and root resorption in Sinclair minipigs

AIM

The use of mini implants to create a passive intraoral anchorage point has been mainly tested in clinical trials. In this study, an experimental integrated approach evaluated mini implant loading protocols (immediate vs. delayed loading) on bone remodelling and mini implant stability and the consequent degree of dental intrusion and apical root resorption.

METHODS

A total of 40 Absoanchor® mini implants with 1.2mm diameter and 8mm length were placed in a total of 5 minipigs, 8 per animal, 2 in each hemiarch. Each implant was attached through a lingual button to the vestibular side of the second and fourth premolars with a nitinol coil spring of 150g force. The analysis of morphological aspects included the degree of dental movement, mini implant stability, and new bone formation over the mini implant heads. Bone mini-implant interface and modifications of dental root in response to intrusion were studied by light and electron microscopy.

RESULTS

The rate of mini implant success was>98%, mainly in those subjected to immediate loading. This loading protocol promoted a high degree of osseointegration along with a high degree of intrusive dental movement, particularly of the second premolars. However, the radiological and histological studies showed a low degree of root resorption. Associated with the high intrusive movement, the penetration of the root apexes produced an inner cortical surface deformation of the maxillary sinus floor by remodeling and bone growth.

CONCLUSION

In minipigs immediate loading of smooth mini implants promoted a high degree of intrusive movement particularly of the second premolars, stimulated bone growth and osseointegration, but extensive root resorption was not observed.

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

OBJECTIVE

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.

BACKGROUND DATA

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

In vitro study of human osteoblast proliferation and morphology on orthodontic mini-implants

OBJECTIVE

To evaluate the proliferation and morphology of human osteoblasts cultured on two brands of mini-implants after 24, 48, and 72 hours, in addition to the chemical composition found on their surface.

MATERIALS AND METHODS

Two brands of mini-implant (Morelli and Neodent) were evaluated; polystyrene was used as a control group (n  =  3). Osteoblasts were cultured on the surface of sterilized mini-implants in a CO2 incubator at different time periods (24, 48, and 72 hours). Osteoblast proliferation was quantified by scanning electron microscopy using up to 5000× magnification, and cell morphology was analyzed by a single observer. For the chemical analysis, spectroscopy X-ray fluorescence was used to identify and quantify chemical components on the surface of the mini-implants.

RESULTS

Two-way ANOVA showed no significant interaction between the factors studied (P  =  0.686). A Tukey test revealed no significant difference in osteoblast proliferation between the mini-implants at all studied periods; however, a difference in cell proliferation was detected between the Neodent and the control group (P  =  .025). For all groups, time had a direct and positive effect on osteoblast proliferation (P < .001). The significant elements present in both brands of mini-implants were titanium, aluminum, vanadium, and iron.

CONCLUSIONS

Osteoblast proliferation was present on the mini-implants studied, which increased over time; however, no significant difference between brands was observed. No difference was seen between the mini-implants evaluated in terms of chemical composition. Cell adhesion after 72 hours suggests that areas of bone remodeling can be achieved, thus initiating the process of mini-implant anchorage.

Effect of Platelet-Rich-Plasma (PRP) and Implant Surface Topography on Implant Stability and Bone

PURPOSE

To evaluate the effect of Platelet-Rich-Plasma (PRP) and different implant surface topography on implant stability and bone levels around immediately loaded dental implants.

MATERIALS AND METHODS

Dental implants were placed in subjects divided into two groups and four subgroups on basis of implant treatment with PRP and implant surface topography used. A total of 30 implants were placed, 15 in each group. For PRP group, implants were placed after surface treatment with PRP. Temporization was done within two weeks and final prosthesis was given after three months. Implant stability was measured with Periotest at baseline, one month and three months. Bone height was measured on mesial & distal side on standardized IOPA x-rays.

RESULTS

A statistically significant difference was noticed in implant stability with PRP at baseline. The effect of PRP on bone height changes was not statistically significant. A synergistic effect of PRP and square thread-form was observed on improved implant stability and bone levels; however, no such effect is seen with PRP and reverse buttress thread-form.

CONCLUSION

Within the limitation of this study, enhancement on implant stability and bone healing was observed with PRP treated implant surfaces, and with use of implant with square thread-form.