The application of mini-implants for orthodontic anchorage

Antimicrobial behavior of nanocoated orthodontic micro-implants: An in vitro study

OBJECTIVE

The need to overcome the failure of orthodontic micro-implants which might reach to 30% has led to the development of different methods, one of which is nanoparticle deposition.

AIM OF STUDY

To evaluate the anti-microbial efficiency of TiO2 and ZnO nanoparticles (NP) when used as a coating for orthodontic micro-implants.

METHODS

Thirty titanium alloy micro-implants were used in the presented study. They were divided into three groups according to the coating method and the coating materials used: the control group without surface coating; the titanium dioxide (TiO2)-coated group, in which direct current (DC) spattering was used to coat the micro-implants with a TiO2 layer; and the TiO2 and zinc oxide (TiO2ZnO)-coated group, in which the micro-implants were coated with a TiO2 layer via direct current (DC) spattering and a zinc oxide (ZnO) layer via laser vacuum. The micro-implant surfaces were characterized using scanning electron microscopy (SEM) and an energy-dispersive spectrometer (EDS). The antibacterial susceptibility was assessed using gram-positive and gram-negative bacteria.

RESULTS

SEM and EDS tests confirmed the coating of the micro-implants in the TiO2- and TiO2ZnO-coated groups. The micro-implants in the TiO2- and TiO2ZnO-coated groups demonstrated higher antibacterial ability than the control group.

CONCLUSION

This study demonstrated the significance of improving the surface of orthodontic micro-implants by coating them with TiO2 and ZnO nanoparticles to improve osseointegration and prevent biofilm formation.

Evaluation of safe areas for miniscrew use according to various skeletal anomalies with CBCT

OBJECTIVES

We aimed to determine safe areas to apply miniscrews in the interradicular region of the maxilla and mandible in individuals with various sagittal skeletal malocclusions.

MATERIALS AND METHODS

Cone beam-computed tomography images of 159 individuals were used. Individuals were divided into three groups: Class I, Class II, and Class III. In the sagittal plane, 3-6-9-mm apical sections were determined from the alveolar crest apex. The buccal cortical bone thickness, interradicular distance, and buccolingual bone distances were measured.

RESULTS

In the buccal cortical bone thickness, we observed statistically significant differences between the classes except for the 1-1 region in the maxilla and all regions and sections in the mandible (p < 0.05). The differences in the buccolingual bone distance between classes were statistically significant, except for the 3-mm and 6-mm sections in the 3-4 and 4-5 regions of the maxilla, the 9-mm sections in the 1-2 and 2-3 regions, the 6-mm and 9-mm sections in the 3-4 region, and the 6-mm section in the 4-5 regions of the mandible (p < 0.05). The differences in the interradicular bone distance were statistically significant between the classes in all regions and sections of the mandible except the 6-mm sections in the 1-2 region and in all sections of the maxilla except the 6-mm sections in the 3-4 region (p < 0.05).

CONCLUSIONS

We observed significant differences in the buccal cortical bone thickness, interradicular bone distance, and buccolingual bone distance among individuals.

CLINICAL RELEVANCE

Understanding the anatomy of interradicular regions and preventing complications.

Ridge mini-implants, a versatile biomechanical anchorage device whose success is significantly enhanced by splinting: a clinical report

OBJECTIVES

This clinical report aims to highlight the factors affecting the clinical success of alveolar ridge mini-implants used for orthodontic anchorage and provide an overview of the biomechanical versatility of this miniscrew and steps involving the proper technique of its placement.

METHODS

For this clinical report, charts for 295 patients who had temporary anchorage devices (TADs) were screened. Twenty patients [15 females and 5 males: mean age = 38.15 ± 15.10 years] with 50 alveolar ridge mini-screws were assessed. A descriptive summary of the main factors affecting their clinical success and the technique employed for their placement was comprehensively discussed and illustrated, in addition to the presentation of some clinical cases illustrating their potential clinical uses.

RESULTS

The survival duration (7.32 ± 9.01 months) and clinical success of the alveolar ridge mini-implants that failed (19/50) seem to be affected primarily by 2 factors: splinting; none of the splinted mini-implants failed (0/10) compared to (19/40) of the single mini-implants that failed, and the length of the used mini-implant; the average length of the mini-implants that did not fail was 9.23 mm. Additionally, it appears that these mini-implants are biomechanically robust and durable, those that did not fail had an average survival duration of 35.97 ± 19.79 months.

CONCLUSION

Ridge mini-implants offer significant biomechanical versatility in patients with partially edentulous ridges needing complex pre-prosthetic orthodontic movements. The presence of splinting and the length of the used mini-implants are factors that might affect the clinical success of the alveolar ridge mini-implants.

Effect of Splinting on Orthodontic Mini-Implant Tipping and Bone Histomorphometric Parameters: An In Vivo Animal Model Study

This study aimed to address the stability of orthodontic mini-implants submitted to an immediate orthodontic functional load, in splinted or unsplinted conditions, further characterizing the histomorphometric parameters of the neighboring bone tissue, in an in vivo experimental model. Mini-implants (1.4 × 6.0 mm) were placed in the proximal tibia of New Zealand White rabbits and immediately loaded with a 150 g force. Tissue healing was characterized within 8 weeks. Microtomography was used to assess the mini-implants' tipping and bone histomorphometric indexes. Loaded implants were evaluated in splinted and unsplinted conditions, with data being compared to that of unloaded mini-implants with the Kruskal-Wallis nonparametric test, followed by Dunn's multiple comparison tests. The splinting of mini-implants submitted to immediate orthodontic loading significantly reduced the tipping to levels similar to those of unloaded mini-implants. Immediate loading further increased the histomorphometric indexes associated with bone formation at the peri-implant region, in both splinted and unsplinted conditions, with no significant differences between the tension and compression regions. Accordingly, within this experimental setting, splinting was found to lessen tipping and mini-implants' displacement, without affecting the increased bone formation at the peri-implant region, induced by a functional orthodontic load.

Quantitative assessment of ramal bone width and the proximity of the inferior canal for the predictable insertion of ramal implants: Cone-beam computed tomography study

Objectives:

The study aimed to investigate the optimum level for the placement of ramal implants as a source of anchorage for disimpacting mandibular molars. The criteria in relation to the maximum transverse width of the ramal bone and proximity of the implant to the inferior alveolar canal (IAC) were evaluated using a three-dimensional cone-beam computed tomography scan for predictable placement of ramal implants.

Material and Methods:

The cone-beam computed tomographic scans of 53 untreated patients (aged between 18 and 48 years) were utilized in this study. The maximum transverse width of the ramus and the proximity to the IAC from the site of insertion were measured at six different levels above the central groove of the mandibular first molar. To measure the proximity to the IAC, the mid-point of the maximum transverse width of the ramus was selected as the site of insertion of the implant.

Results:

The maximum and minimum transverse ramal width was 12.48 ± 1.76 mm at 3 mm and 10.42 ± 2.08 mm at 8 mm above the central groove of the permanent mandibular first molar. An average clearance of 9.62 ± 2.59 mm was measured from the site of insertion to the IAC at the different levels evaluated.

Conclusion:

The ramus of the mandible can be a predictable site for implant placement provided the variations in the anatomical structures have been carefully analyzed. It can be concluded that the ramal implants can be safely placed at a level 3–8 mm above the permanent mandibular first molar in relation to the occlusal plane.

Failure rates and factors associated with infrazygomatic crestal orthodontic implants - A prospective study

Objective

Infrazygomatic crestal (IZC) implants have gained increased popularity over the past few years. Hardly any studies have been done to assess the rate and reasons for failure of IZCs. This prospective study was planned and designed with the primary objective of assessing the rate of failure of bone-screws (BS) placed in the infrazygomatic crest. In continuation, the secondary objective was to assess the factors that were associated with the failure.

Materials and methods

The study was carried out by taking a detailed case history, (age, gender, vertical skeletal pattern, medical history), photographic records, radiographs, and clinical examination of a total of 32 randomly selected. patients of south indian origin who required infrazygomatic implants bilaterally as the choice of anchorage conservation to retract their incisors. All selected subjects were required to take a PA Cephalogram after the implant placement. The age of the patients ranged from 18 to 33 with an average age of 25 years. The patient log was maintained which included the treatment mechanics, status of oral hygiene, stability of implants, time of loading of the implant, presence of inflammation and time of failure of implant. The angulation of implant was measured on a digital PA cephalogram using Nemoceph software. These parameters were examined to evaluate independent and dependent variables using the Chi-Square test and Fischer's exact test.

Result

A failure rate 28.1% for IZC placed in the infrazygomatic crest region was observed. Patients with a high mandibular plane angle, poor oral hygiene, immediately loaded implant, peri-implantitis, and severe clinical mobility showed higher failure rates. Variables such as age, gender, sagittal skeletal pattern, length of the implant, type of movement, occluso-gingival position, method of force application, and angle of placement were not significantly associated with implant failure.

Conclusion

Oral hygiene and peri-screw inflammation must be controlled to minimize the failure of bone screws placed in the infrazygomatic crest region. Loading of the implant should be done after a latent period of two weeks. A higher failure rate was observed in patients with vertical growth pattern.

Identification of Senescent Cells in Peri-Implantitis and Prevention of Mini-Implant Loss Using Senolytics

Peri-implantitis is a disease that causes the detachment of orthodontic mini-implants. Recently, stress-induced senescent cells have been reported to be involved in various inflammatory diseases. Senescent cell-eliminating drugs, termed "senolytics", can improve the symptoms of such diseases. However, the relationship between peri-implantitis and senescent cells remains unclear. In this study, we evaluated the presence of senescent cells in a rat peri-implantitis model developed with a gum ring. The effect on bone resorption and implant loss was also investigated with and without senolytics (Dasatinib and Quercetin). The number of senescence markers (p19, p21, and p16) was found to increase, and implant detachment occurred in 24 days. After the administration of senolytics, the number of senescence markers decreased and implant detachment was inhibited. This study suggests that senescent cells aggravate peri-implantitis and senolytic administration latently reduces implant loss by inhibiting senescence-related mechanisms.

Evidence-based selection of orthodontic miniscrews, increasing their success rate in the mandibular buccal shelf. A randomized, prospective clinical trial

Background

Skeletal anchorage has made it possible to perform complex orthodontic tooth movements that are difficult or even impossible to achieve with conventional orthodontic treatment. Mandibular buccal shelf miniscrews, used for distalization, play a particularly important role in treatment of Class III malocclusion. Unfortunately, stability of the miniscrews placed in the mandible is still considered at higher risk of failure compared to other intraoral locations. The aim of our study was to determine the influence of the miniscrew size on their long-term stability, occurrence of oral mucosa inflammation and pain lasting over 48 h after implantation.

Methods

184 Absoanchor^® miniscrews (Dentos, South Korea) in two sizes: SH2018-10 (length 10 mm, ø 1.8–2.0 mm) and SH1514-08 (length 8 mm, ø 1.4–1.5 mm) were inserted in the mandibular buccal shelf in 92 Caucasians aged 20–50 years, diagnosed with Class III malocclusion that required en-masse distalization of the mandibular dentition. Data was statistically analyzed with the level of significance set at p = .05.

Results

91.3% of the SH2018-10 and 75% of the SH1514-08 miniscrews were stable, and this difference was statistically significant (p < .05). Inflammation of the oral mucosa was noticed around both types of miniscrews and affected 50% of the SH2018-10 and 26.09% of the SH1514-08 group (p < .05). Pain lasting longer than 48 h after implantation was related to 60.87% and 20.65% of the SH2018-10 and the SH1514-08 miniscrews (p < .05), respectively. Inflammation associated with larger SH2018-10 miniscrews did not affect their stability (p > .05), contrary to the SH1514-08 ones (p < .05). When inflammation was present, the overall success rate declined to 64.29%, from 94.74% noted for TADs without inflammation. According to the log-rank test, smaller TADs failed significantly sooner than the larger ones (p = .002).

Conclusion

Larger SH2018-10 miniscrews are the anchorage of choice for the mandibular buccal shelf, despite triggering inflammation and long-lasting pain significantly more often than the smaller ones. Therefore, this issue should be discussed with every patient prior to miniscrew use. Trial registration ID: ClinicalTrials.gov Identifier: NCT05280678 Date of Registration: 15/03/2022. Retrospectively registered.

Mini-Implant Rejection Rate in Teenage Patients Depending on Insertion Site: A Retrospective Study

Mini-implants have undeniable advantages in Orthodontics. However, the use of mini-implants shows some limitations and disadvantages related to patient age, the quality of the bone tissue, the characteristics of the oral mucosa, implant site, the state of health of the organism and the quality of oral hygiene. The aim of this paper was to analyze the rejection rate of mini-implants in teenage patients, depending on their insertion site, and examine their stability up to three months after insertion. This retrospective study was conducted on dental charts belonging to patients aged between 12 and 17 years, from Oradea, Romania. The mini-implants were placed for various therapeutic reasons and were inserted in the following sites: buccal maxillary area, the infrazygomatic region, palatal area, buccal mandibular area and lingual area; they had a diameter of 1.6 mm (inter-radicular spaces) and of 2 mm (nonbearing tooth areas), and a length of 6–8 mm (mandible) or 8–10 mm (maxilla). The rejection rate was checked in the first month, second month, third month and after the third month from insertion. A total of 432 patients were included in the study, and they had a total of 573 mini-implants. Most implants were placed in the buccal region of the maxilla (27.7%), and most patients had one mini-implant placed (65.7%). The highest rejection rate was obtained in the first month (15.2%). The rejection rate between genders was similar. The mini-implants from the buccal mandibular region had a significantly higher rate of rejection in the first month (M1) in comparison to the mini-implants from the palatal region (24.4% vs. 8.3%). The mini-implants from the lingual region of the mandible had a significantly higher rate of rejection in the second month (M2) in comparison to the mini-implants from the infrazygomatic or the palatal region (10.5% vs. 0%/0%). Mini-implants are very useful for carrying out various orthodontic treatments, but their stability should be enhanced.

Intrusion of Maxillary Posterior Teeth by Skeletal Anchorage: A Systematic Review and Case Report with Thin Alveolar Biotype

This study aimed to review the literature related to the intrusion of maxillary posterior teeth in subjects needing pre-prosthetic restoration or orthodontic treatment due to anterior open bite, and to report a thin alveolar biotype case needing a pre-prosthetic intrusion of maxillary teeth by introducing a novel, personalized method of intrusion measurement. An electronic search was conducted between February 2022 and March 2022 in the following databases: PubMed, Scopus, Embase, Web of Science, and Lilacs; the terms “tooth movement techniques”, “orthodontic anchorage procedures”, “tooth intrusion”, “intrusion”, “molar”, “premolar”, and “human” were surveyed. Eighteen articles were included in this review; the mean amount of intrusion ranged from between 2.1 ± 0.9 mm and 4.57 ± 0.98 mm (being mostly 2–3 mm). The intrusion force varied between 100 and 500 g; 10 articles reported miniscrews (MS), 7 reported zygomatic plates (ZP), and 1 publication reported both anchorage types. The average treatment time was 6.9 months for MS and 7.9 months for ZP. Levelling the occlusal plane by intrusion of the upper posterior teeth can be achieved by skeletal anchorage. The stability of the obtained results, shortening treatment time, and controlling treatment outcome are the main goals for a complex surgical and orthodontic treatment approach.

Novel digital technique to analyze the accuracy and intraoperative complications of orthodontic self-tapping and self-drilling microscrews placement techniques: An in vitro study

INTRODUCTION

The objectives of this study were to analyze and compare the accuracy and intraoperative complications of orthodontic self-tapping and orthodontic self-drilling microscrew placement techniques.

METHODS

A total of 60 orthodontic microscrews were randomly distributed into 2 study groups: (1) group A, orthodontic self-drilling microscrew placement technique (n = 30); and (2) group B, orthodontic self-tapping microscrew placement technique (n = 30). Cone-beam computed tomography and intraoral scans were performed before and after the orthodontic microscrew placement techniques and uploaded in 3-dimensional implant planning software to analyze the deviation angle and the horizontal deviation measured at the coronal entry point and apical endpoint between orthodontic microscrews planned and performed, using the Student t test. In addition, intraoperative complications, such as root perforations after the orthodontic microscrews placement and the fracture of the orthodontic self-tapping microscrews during their placement, were also analyzed.

RESULTS

The paired t test revealed statistically significant differences at the apical endpoint (P <0.001) between planned and performed orthodontic self-tapping and self-drilling microscrew placement techniques. However, the paired t test revealed no statistically significant differences at the coronal entry point (P = 0.1047) and angular deviations (P = 0.3251) between planned and performed orthodontic self-tapping and self-drilling microscrews placement techniques. Furthermore, 4 root perforations were observed at the orthodontic self-tapping microscrews placement technique, and 1 orthodontic self-tapping microscrew was fractured during the placement procedure.

CONCLUSIONS

The results show that the orthodontic self-drilling microscrew technique increases the accuracy of orthodontic microscrews placement, resulting in fewer intraoperative complications.

Orthodontic mini-implants: clinical and peri-implant evaluation

The study evaluated the clinical changes of orthodontic mini-implants (MI) inserted for the purpose of anchoring during orthodontic treatment. The null hypotheses were: 1-that there is no correlation between proximity of the MI to the root and peri-implantitis or mobility; 2-that peri-implantitis does not interfere with mobility; 3-that the pain is not related to mobility or peri-implantitis. Forty (40) patients were selected and the MI were evaluated for each patient. MI in the upper and lower arch were evaluated for a period of approximately 6 months with relationship to the distance MI - root, peri-implantitis, mobility, biological damage and pain through the analysis of periapical radiography and clinical/periodontal evaluation. The evaluations were performed out by means of scores and a correlation was made between the variables. No statistically significant differences were found between the upper and lower arch in the variables evaluated, except for the mobility that was more present in the lower arch (p = 0.0336). There was a correlation between peri-implantitis and mobility (p = 0.0003) and between pain and mobility (p = 0.0443). However, there was no correlation between a greater degree of peri-implantitis and greater mobility (p = 0.7054). In addition, the MI placed too close to the root showed peri-implantitis (p = 0.0142). The null hypotheses were rejected because there was a positive correlation between the analyzes. The placement of MI close to the root led to greater peri-implantitis. Patients who reported pain had greater mobility of the MI and peri-implantitis led to greater mobility.

CBCT comparison of buccal shelf bone thickness in adult Dravidian population at various sites, depths and angulation - A retrospective study

INTRODUCTION

It is important to understand the variations in the bone thickness of the buccal shelf region among different ethnic groups, as these variations will influence the placement and success of the buccal shelf mini-screw.

OBJECTIVES

The primary objective was to analyse the total buccal bone and cortical bone thickness of the mandibular buccal shelf region (MBS) at various depths, mesiodistal positions and angulations in Dravidian population and to find the best site for insertion of buccal shelf mini-implant.

MATERIAL AND METHODS

This was a retrospective study done on 30 cone-beam computed tomography samples collected from 30 subjects, aged 16 to 25 years and of Dravidian origin, who reported for orthodontic treatment. The total bone and cortical bone thicknesses of the buccal shelf regions were evaluated in relation to the Disto-Buccal cusp of 1st Molar (DB1M), Mesio-Buccal cusp of 1st Molar (MB1M), and Disto-Buccal cusp of 2nd Molar (DB2M) at the depths of 4mm, 8mm and 12mm from cemento-enamel junction (CEJ). The total bone thickness and the clearance from the root and cortical bone thickness were assessed at angulations of 30, 45 and 60 degrees from 5mm below the root apex. ANOVA and Post Hoc tests were done to compare the bone thickness measurements. Kappa statistics was done to assess the intraobserver reliability. Pearson's correlation test was done to find the correlation between growth pattern and thickness of the bone.

RESULTS

The mean age group of the included sample was 20.5 years. Maximum total bone thickness was observed at a depth of 8mm in relation to the MB2M (6.41±0.29mm) and 12mm in relation to the DB2M 6.56±0.28mm and the P value was 0.000. Maximum bone thickness was present in the DB2M at 30° followed by DB2M 45° of 11.42±0.35mm and 10.89±0.3mm and the P value was 0.000. The maximum clearance from the root was observed at 30° and 45° in the DB2M with 5.35±0.2mm and 5.18±0.27mm, the P value was 0.014 when comparing angulation 30 and 45°. The DB2M had a cortical bone thickness of 2.97±0.15mm and 2.8±0.2mm at 45° and 60° and was statistically significant.

CONCLUSIONS

The insertion site with optimal bone quantity was observed in relation to the buccal aspect of distobuccal cusp of 2nd molar at depth of 8mm or greater with a preferred angulation of 30-45° to have adequate clearance from the molar tooth roots and to penetrate a region of cortical bone of minimum 2mm.

Treatment effects of Carriere Motion Appliance on patients with class II malocclusion: A systematic review and meta-analysis

OBJECTIVE

To investigate the treatment effects of Carriere Motion Appliance (CMA) on class II patients.

METHODS

A comprehensive electronic search was performed in PubMed, Scopus, Web of science, ScienceDirect, ProQuest (dissertation and thesis), Google Scholar and ClinicalTrials.gov. All types of clinical trials that contained at least pre- and post-treatment measures of patients treated by CMA were included in this systematic review and meta-analysis. The risk of bias was assessed for all included studies. The considered outcomes were the skeletal, dento-alveolar, soft tissues, temporomandibular joint and airway changes, electromyographic activity and stability.

RESULTS

Sixteen studies were included in this systematic review and meta-analysis. The absence of randomized controlled trials which could induce confounding and selection of participant bias is considered the main risk of bias affecting the available studies. Regarding the skeletal changes, no significant effects were appreciated (changes in SNB angle; SMD=-0.13; 95% CI (-0.57, 0.31); P=0.58. Changes in SN-MP; SMD=-0.11; 95% CI (-0.54, 0.33); P=0.64). With respect to the dento-alveolar changes, an increased lower incisor's proclination (L1-MP) was observed; SMD=-0.69; 95% CI (-1.14, -0.24); P=0.003. CMA caused an increase in the airway volume, an increase in the masseter and temporalis muscles activities and a minor relapse of malocclusion after 4-years of follow-up. The results should be taken with caution because only secondary level of evidence was found.

CONCLUSIONS

The CMA used for the treatment of class II malocclusion did not cause skeletal changes; however, largely dento-alveolar effects were noticed. Prospective randomized clinical trials are highly recommended.

The correlation among gripping volume, insertion torque, and pullout strength of micro-implant

Background/purpose

The fixation stability is the key factor for orthodontic micro-implant to succeed. This study evaluated the mechanical properties of three types of micro-implants by analyzing their structural configurations.

Materials and methods

Thirty micro-implants of three types (diameter 1.5 mm, Types A, B, C) were assessed. All micro-implants were manually driven into artificial bones at an 8-mm depth. The insertion torque (IT), pullout strength (PS), and gripping volume (GV) of each type were measured. The indexes of mechanical properties denoted as the PS/IT, GV/IT and PS/GV ratios. Intergroup comparisons and intragroup correlation were examined using statistical analysis.

Results

Type B had the greatest inner–outer diameter ratio (0.67), and Type A had the smallest (0.53). The IT of Type A (5.26 Ncm) was significantly (p = 0.038) lower than that of Type C (8.8 Ncm). There was no significant difference in the pullout strength. The GV of Type A (9.7 mm³) was significantly greater than Type C (8.4 mm³). Type C was significantly greater than Type B (7.2 mm³). The ratios of mechanical properties (PS/IT, PS/GV, and GV/IT) were found significant in intergroup comparison. The PS/GV ratio was in order: Type B (26.5) > Type A (23.0) > Type C (20.2). Spearman's rho rank correlation test showed that PS of Type B was correlated significantly with GV.

Conclusion

The design of thread and gripping volume were the important factors that contributes to the mechanical strengths of micro-implant.

Debonding Shear Strength of Orthodontic Tubes Bonded to Skeletal Anchorage Miniplates with Different Agents

Introduction:

Most miniplates used for skeletal anchorage lack built-in orthodontic devices. To address this issue, orthodontists must use creative solutions, such as bonding buttons, brackets, or tubes directly to the miniplates, thus making them more versatile devices that provide a wider range of tooth movement possibilities. The purpose of the present study was to ascertain the debonding strength in Megapascals (MPa) of orthodontic accessories bonded to skeletal anchorage miniplates with different bonding agents.

Methods:

Forty specimens were divided into two equal groups by bonding agent: Group 1, resin (Transbond XT®, 3M ESPE); Group 2, cyanoacrylate (Scotchbond®, 3M ESPE). Shear strength testing was performed in an EMIC DL-2000 universal testing machine.

Results:

The results obtained were 2.28 ± 0.44 MPa for Group 1 and 4.90 ± 0.76 MPa for Group 2. The Kolmogorov-Smirnov test was used to assess the normality of data distribution. Student's t-test was used to compare means in the response variable.

Conclusion:

A statistically significant difference was observed between groups. However, both bonding agents provided strength in excess of that needed for secure orthodontic tooth movement.

The thickness of posterior buccal attached gingiva at common miniscrew insertion sites in subjects with different facial types

INTRODUCTION

The purpose of this study was to assess the thicknesses of maxillary and mandibular posterior buccal approximal attached gingiva at common miniscrew insertion sites, which has critical importance in determining miniscrew length, in subjects with different facial types.

METHODS

One hundred seventy-four subjects with no transversal skeletal discrepancy were included in this study. The facial types of these subjects were evaluated in the sagittal and vertical directions. In the sagittal direction, the subjects were assigned into 3 groups: skeletal Class I, II, and III. Also, each of these groups was divided into subgroups in the vertical direction: low angle, norm, and high angle. Transgingival probing was used to measure the thickness of the buccal attached gingiva.

RESULTS

The thickness of the buccal attached gingiva between the second premolar-first molar ranged from 1.18 ± 0.33 to 1.46 ± 0.28 mm and from 1.28 ± 0.30 to 1.58 ± 0.37 mm in the maxilla and mandible, respectively. The thickness of the buccal attached gingiva between the first-second molars ranged from 1.31 ± 0.41 to 1.60 ± 0.62 mm and from 1.36 ± 0.43 to 1.72 ± 0.52 mm in the maxilla and mandible, respectively. In terms of the thicknesses of the buccal attached gingiva of second premolar-first molar and first-second molars, no statistically significant difference was found between subjects with different facial types.

CONCLUSIONS

It was determined that the thicknesses of maxillary and mandibular posterior buccal approximal attached gingiva varied between 1.18-1.72. At this point, the insertion of miniscrews of 7-8 mm in length was recommended for maxillary and mandibular posterior buccal regions, in order to obtain adequate insertion depth.

Investigation of the optimal design of orthodontic mini-implants based on the primary stability: A finite element analysis

Background. The design of an orthodontic mini-implant is a significant factor in determining its primary stability and its clinical success. The aim of this study was to measure the relative effect of mini-implant design factors on primary stability of orthodontic mini-implants.

Methods. Thirty-two 3-dimensional assemblies of mini-implant models with their surrounding bone were generated using finite element analysis software. The maximum displacement of each mini-implant model was measured as they were loaded with a 2-N horizontal force. Employing Taguchi’s design of experiments as a statistical method, the contribution of each design factor to primary stability was calculated. As a result of the great effect of the upper diameter and length, to better detect the impact of the remaining design factors, another set of 25 models with a fixed amount of length and diameter was generated and evaluated.

Results. The diameter and length showed a great impact on the primary stability in the first set of experiments (P<0.05). According to the second set of experiments, increased taper angle in the threaded and non-threaded area decreased the primary stability. There was also an optimum amount of 2.5 mm for threaded taper length beyond which the primary stability decreased.

Conclusion. It is advisable to increase the diameter and length if primary stability is at risk. In the second place, a minimum amount of taper angle, both in the threaded and non-threaded area with an approximate proportion of 20% of threaded taper length to MI length, would be desirable for MIs with a moderate size.

Gripping and Anchoring Effects on the Mechanical Strengths of Orthodontic Microimplants

PURPOSE

The aim of this study was to evaluate the mechanical strengths in 5 different designs of orthodontic microimplants by analyzing their configuration of structure.

MATERIALS AND METHODS

Thirty microimplants of 5 types (diameter 1.5 mm: type A, B, and C; diameter 1.3 mm: type D and E) were assessed. All microimplants were manually driven into the artificial bones at a 7-mm depth. The anchor area (AA), gripping area (GA), insertion torque (IT), Periotest value (PTV), and pullout strength (PS) were measured. Intergroup and intragroup comparisons were used to detect their significant differences.

RESULTS

In the intergroup comparison, type D had a least IT (4.5 Ncm). In the PTV analysis, type B had the largest AA (7.76 mm) and its PTV (1.6) was significantly least than the others. In the PS test, type C had the largest GA (2.40 mm) and its PS was the largest. Intragroup comparisons (IT and PS), type A, and type E presented positively significant correlation. GA revealed positive with PS, and AA showed reverse tendency with PTV.

CONCLUSION

The more AA of microimplants, the more stable they are. The more GA of microimplants, the more PS they are. Therefore, type C was better than the others because it had the largest GA and second largest AA.

Influence of interradicular and palatal placement of orthodontic mini-implants on the success (survival) rate

BACKGROUND

The purpose of this retrospective cohort study was to investigate the success rates of orthodontic mini-implants (OMIs) placed in different insertion sites and to analyse patient and site- related factors that influence mini-implant survival.

METHODS

Three hundred eighty-seven OMIs were inserted in 239 patients for orthodontic anchorage and were loaded with a force greater than 2 N. Two different insertion sites were compared: 1. buccal inter-radicular and 2. palatal, at the level of the third palatal ruga. Survival was analysed for location and select patient parameters (age, gender and oral hygiene). The level of statistical significance was set at p < 0.05.

RESULTS

The overall success rate was 89.1%. There were statistically significant differences between insertion sites; success rate was 98.4% for OMIs placed in the anterior palate and 71% for OMIs inserted buccal between roots (p < 0.001).

CONCLUSIONS

Success rate of OMIs was primarily affected by the insertion site. The anterior palate was a more successful location compared to buccal alveolar bone.

Comparison of the success rate between self-drilling and self-tapping miniscrews: a systematic review and meta-analysis

Background

Both the self-drilling and self-tapping miniscrews have been commonly used as anchorage reinforcement devices in orthodontic treatment.

Objective

The aim of this study was to compare the success rates of self-drilling and self-tapping miniscrews in orthodontic practice.

Search methods

Literature searches were performed by electronic search in database including PubMed, Embase, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure and SIGLE, and manual search of relevant journals and reference lists of included studies.

Eligibility criteria

Randomized controlled trials, clinical controlled trials and cohort studies comparing the success rates of self-drilling and self-tapping miniscrews as orthodontic anchorage.

Data collection and analysis

The data of success rates and root contact rates were extracted by two investigators independently. After evaluating the risk of bias, the odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Subgroup analysis was performed on the basis of study design, follow-ups, participant ages and immediate/delayed loading. Sensitivity analysis was performed to test the stability of the results in meta-analysis.

Results

Six studies assessed as high quality were included in the meta-analysis. The meta-analysis results showed no difference between the two types of screws in the success rates. The root contact rates of the two screws were similar, while self-drilling miniscrews displayed higher risk of failure when contacting with a tooth root.

Conclusions

Currently available clinical evidence suggests that the success rates of self-tapping and self-drilling miniscrews are similar. Determination of the position and direction of placement should be more precise when self-drilling miniscrews are used in sites with narrow root proximity.

Registration

None.

Conflict of interest

None.

Insertion torque, resonance frequency, and removal torque analysis of microimplants

This study aimed to compare the insertion torque (IT), resonance frequency (RF), and removal torque (RT) among three microimplant brands. Thirty microimplants of the three brands were used as follows: Type A (titanium alloy, 1.5-mm × 8-mm), Type B (stainless steel, 1.5-mm × 8-mm), and Type C (titanium alloy, 1.5-mm × 9-mm). A synthetic bone with a 2-mm cortical bone and bone marrow was used. Each microimplant was inserted into the synthetic bone, without predrilling, to a 7 mm depth. The IT, RF, and RT were measured in both vertical and horizontal directions. One-way analysis of variance and Spearman's rank correlation coefficient tests were used for intergroup and intragroup comparisons, respectively. In the vertical test, the ITs of Type C (7.8 Ncm) and Type B (7.5 Ncm) were significantly higher than that of Type A (4.4 Ncm). The RFs of Type C (11.5 kHz) and Type A (10.2 kHz) were significantly higher than that of Type B (7.5 kHz). Type C (7.4 Ncm) and Type B (7.3 Ncm) had significantly higher RTs than did Type A (4.1 Ncm). In the horizontal test, both the ITs and RTs were significantly higher for Type C, compared with Type A. No significant differences were found among the groups, and the study hypothesis was accepted. Type A had the lowest inner/outer diameter ratio and widest apical facing angle, engendering the lowest IT and highest RF values. However, no significant correlations in the IT, RF, and RT were observed among the three groups.

Implants for orthodontic anchorage: success rates and reasons of failures

INTRODUCTION

The aims of this study were to analyze the success rate of mini-implants and miniscrews and to report the reasons behind them.

MATERIALS AND METHODS

An electronic literature search from PubMed databases and a hand search in implant- and orthodontic-related journals were performed until December 31, 2011. Human clinical studies in English that reported temporary anchorage devices used for orthodontic purpose with at least 6 months follow-up were included. In addition, the minimal number of implants had to be at least 10. Implants placed in maxilla, mandible, and hard palate were included.

RESULTS

The initial search resulted in 847 articles, of which 46 were further evaluated. Finally, 29 studies were qualified and classified into 2 groups: implants placed in maxilla and mandible (group 1) and implants placed in hard palate (group 2). A meta-analysis performed for groups 1 and 2 showed 87.8% and 93.8% survival rate, respectively. In addition, the most common cause for implants failure was surgery-related factors.

CONCLUSION

Mini-implant survival rate is location dependent, with those placed in the palate showing higher success rates. In addition, failures most commonly occur because of surgery-related factors.

Prognostic factors associated with the success rates of posterior orthodontic miniscrew implants: A subgroup meta-analysis

OBJECTIVE

To systematically review previous studies and to assess, via a subgroup meta-analysis, the combined odds ratio (OR) of prognostic factors affecting the success of miniscrew implants (MIs) inserted into the buccal posterior region.

METHODS

Three electronic searches that were limited to articles on clinical human studies using MIs that were published in English prior to March 2015 were conducted. The outcome measure was the success of MIs. Patient factors included age, sex, and jaw of insertion (maxilla vs. mandible), while the MI factors included length and diameter. A meta-analysis was performed on 17 individual studies. The quality of each study was assessed for non-randomized studies and quantified using the Newcastle-Ottawa Scale. The meta-analysis outcome was a combined OR. Subgroup and sensitivity analyses based on the study design, study quality, and sample size of miniscrews implanted were performed.

RESULTS

Significantly higher success rates were revealed for MIs inserted in the maxilla, for patients ≥ 20 years of age, and for long MIs (≥ 8 mm) and MIs with a large diameter (> 1.4 mm). All subgroups acquired homogeneity, and the combined OR of the prospective studies (OR, 3.67; 95% confidence interval [CI], 2.10-6.44) was significantly higher in the maxilla than that in the retrospective studies (OR, 2.10; 95% CI, 1.60-2.74).

CONCLUSIONS

When a treatment plan is made, these risk factors, i.e. jaw of insertion, age, MI length, and MI diameter, should be taken into account, while sex is not critical to the success of MIs.

Comparison of pain perception during miniscrew placement in orthodontic patients with a visual analog scale survey between compound topical and needle-injected anesthetics: A crossover, prospective, randomized clinical trial

INTRODUCTION

The use of a compound topical anesthetic (CTA) instead of an injection of a local anesthetic for placing miniscrew implants offers advantages to both the clinician and the patient. The purpose of this crossover, prospective, randomized clinical trial was to compare the clinical effectiveness of a CTA with that of a needle injection of local anesthetic for miniscrew placement.

METHODS

Twenty-four orthodontic patients in a university clinic were recruited; they required bilateral buccal miniscrews for orthodontic anchorage. Eligibility criteria included healthy patients with no special needs; over 8 years of age and 25 pounds; not taking sulfonamides, monoamine oxidase inhibitors, tricyclic antidepressants, or phenothiazines; and not allergic to ester-type local anesthetics or any of the other materials used in the study. A computer generated a randomization list. The allocation was randomized by anesthetic protocol and side of the mouth, and was restricted to achieve balance by treatment and side of the mouth. No allocation concealment was applied. Associated with each randomized number was the subjects' assignment into 1 of 4 groups divided by the side of first miniscrew placement and the type of anesthetic. Blinding was done only for data analysis because of clinical limitations. Each patient received a CTA on one side and an injection of anesthetic on the other before miniscrew placement in a crossover study design. The outcome was assessed by measuring pain levels with a 100-mm visual analog scale at 5 time points. Anesthetic failures occurred when the miniscrew could not be fully comfortably placed with a given anesthetic. Data were organized by visual analog scale time points, and descriptive statistics were calculated. A factorial repeated-measures analysis of variance was used to determine any differences.

RESULTS

Twenty-seven patients were assessed for eligibility, and 24 agreed to participate in the study. Patients did not distinguish any differences in pain between the application of the CTA and the injection before or during anesthetic placement, but they experienced more pain with the CTA during miniscrew placement. The mean difference for the entire procedure between the 2 anesthesia types was 24.6 units, and the 95% confidence interval was 18.8 to 30.4, a statistically significant finding (P = 0.0002). The CTA was still viewed as more painful 1 month after the procedures. Significantly more anesthetic failures occurred with the CTA (41.6%) than with the injection (0%). No serious harm was observed in any patient; when significant pain was observed with the CTA, a needle injection of local anesthetic was administered.

CONCLUSIONS

CTAs provided less predictable, often inadequate, and less comfortable anesthesia than an injection of a local anesthetic for managing patient discomfort during miniscrew placement in buccal sites.

REGISTRATION

This trial was not registered.

PROTOCOL

The protocol was determined and approved by the research committee and institutional review board before the trial.

FUNDING

No external funding was used other than the donation of the miniscrews from Rocky Mountain Orthodontics, and no conflict of interest was declared.

Ultraviolet photofunctionalization increases removal torque values and horizontal stability of orthodontic miniscrews

INTRODUCTION

The objective of this study was to examine the effects of ultraviolet-mediated photofunctionalization of miniscrews and the in-vivo potential of bone-miniscrew integration.

METHODS

Self-drilling orthodontic miniscrews made from a titanium alloy were placed in rat femurs. Photofunctionalization was performed by treating the miniscrews with ultraviolet light for 12 minutes with a photo device immediately before implantation. Maximum insertion torque (week 0), removal torque (weeks 0 and 3), and resistance to lateral tipping force (week 3) were examined.

RESULTS

The removal torque at 3 weeks of healing was higher for the photofunctionalized screws than for the untreated screws. The regenerated bone tissue was more intact and contiguous around the photofunctionalized miniscrews than around the untreated ones. The miniscrew-bone complex seemed to produce interface failure, not cohesive fracture, in both groups. The displacement of untreated screws under a lateral tipping force was greater than that of photofunctionalized miniscrews.

CONCLUSIONS

These results suggest that photofunctionalization increases the bioactivity of titanium-alloy miniscrews and improves the anchoring capability of orthodontic miniscrews, even without modification of the surface topography.

A study of success rate of miniscrew implants as temporary anchorage devices in singapore

Objective. To find out the success rate of miniscrew implants in the National Dental Centre of Singapore (NDCS) and the impact of patient-related, location-related, and miniscrew implant-related factors. Materials and Methods. Two hundred and eighty-five orthodontic miniscrew implants were examined from NDCS patient records. Eleven variables were analysed to see if there is any association with success. Outcome was measured twice, immediately after surgery prior to orthodontic loading (T1) and 12 months after surgery (T2). The outcome at T2 was assessed 12 months after the miniscrew's insertion date or after its use as a temporary anchorage device has ceased. Results. Overall success rate was 94.7% at T1 and 83.3% at T2. Multivariate analysis revealed only the length of miniscrew implant to be significantly associated with success at both T1 (P = 0.002) and T2 (P = 0.030). Miniscrew implants with lengths of 10–12 mm had the highest success rate (98.0%) compared to other lengths, and this is statistically significant (P = 0.035). At T2, lengths of 10–12 mm had significantly (P = 0.013) higher success rates (93.5%) compared to 6-7 mm (76.7%) and 8 mm (82.1%) miniscrew implants. Conclusion. Multivariate statistical analyses of 11 variables demonstrate that length of miniscrew implant is significant in determining success.

Primary failure rate for 1680 extra-alveolar mandibular buccal shelf mini-screws placed in movable mucosa or attached gingiva

OBJECTIVE

To compare the initial failure rate (≤4 months) for extra-alveolar mandibular buccal shelf (MBS) miniscrews placed in movable mucosa (MM) or attached gingiva (AG).

MATERIALS AND METHODS

A total of 1680 consecutive stainless steel (SS) 2 × 12-mm MBS miniscrews were placed in 840 patients (405 males and 435 females; mean age, 16 ± 5 years). All screws were placed lateral to the alveolar process and buccal to the lower first and second molar roots. The screw heads were at least 5 mm superior to the soft tissue. Loads from 8 oz-14 oz (227 g-397 g, 231-405 cN) were used to retract the mandibular buccal segments for at least 4 months.

RESULTS

Overall, 121 miniscrews out of 1680 (7.2%) failed: 7.31% were in MM and 6.85% were in AG (statistically insignificant difference). Failures were unilateral in 89 patients and bilateral in 16. Left side (9.29%) failures was significantly greater (P < .001) compared with those on the right (5.12%). Average age for failure patients was 14 ± 3 years.

CONCLUSION

MBS miniscrews were highly successful (approximately 93%), but there was no significant difference between placement in MM or AG. Failures were more common on the patient's left side and in younger adolescent patients. Having 16 patients with bilateral failures suggests that a small fraction of patients (1.9%) are predisposed to failure with this method.

Mini-implants: new possibilities in interdisciplinary treatment approaches

The introduction of mini-implants has broadened the range of tooth movements possible by fixed appliance therapy alone. The limits of fixed orthodontic treatment have become more a matter of facial appearance than anchorage. Many complex cases which would previously have required surgery or functional appliances can now be treated with fixed appliance therapy using mini-implants. A mutilated dentition case where mini-implants were used to provide anchorage for intrusion of molars and retraction of anterior teeth is reported here to illustrate this point.

Evaluation of orthodontic mini-implant placement: a CBCT study

Background

Optimal positioning of orthodontic mini-implants is essential for a successful treatment with skeletal anchorage. This study aims to compare the accuracy of two-dimensional radiographs with a cone beam computed tomography (CBCT) for mini-implant placement.

Methods

An ideal site for mini-implant placement at the buccal interradicular space between the second premolar and the first molar was determined for 40 sites (in 13 patients aged 14 to 28 years) by using CBCT data. The mini-implant placement procedure was then divided into two groups. In CBCT group, mini-implants were placed at the sites determined from CBCT data. In RVG group, mini-implants were placed with the help of two-dimensional digital radiographs and a custom made guide. Postplacement CBCT scans were obtained to determine the accuracy of the mini-implant placement. The results were statistically analyzed with a Mann-Whitney test.

Results

A statistically significant difference (p value = 0.02) was observed between the two groups for deviation from an ideal height of placement of the mini-implants. Deviations in mesiodistal positioning and angular deviation showed a statistically non-significant difference. Three out of twenty mini-implants in the RVG group showed root contact in the mandibular arch that may be attributed to the narrower interradicular space and reduced accessibility in the mandibular posterior region.

Conclusions

Although CBCT provides an accurate three-dimensional visualization of the interradicular space, the two-dimensional intraoral radiograph of the interradicular area provides sufficient information for mini-implant placement. Considering the amount of radiation exposure and cost with the two techniques, it is recommended to use two-dimensional radiographs with a surgical guide for a routine mini-implant placement.

Bivariate optimization of orthodontic mini-implant thread height and pitch

PURPOSE

Mini-implants have been used as anchorage for years, but failure is common in clinical practice. Mini-implant design is a critical factor affecting its stability. The aim of this study was to evaluate the effect of continuous and simultaneous variations of thread height and pitch on the biomechanical properties of an orthodontic mini-implant.

METHOD

A 3D finite element model, composed of a posterior maxilla section and an orthodontic mini-implant, was created. Mini-implant thread height ranged from 0.10 to 0.40 mm, and thread pitch ranged from 0.50 to 2.00 mm. Effects of the implant thread height and pitch on the maximum Von Mises stresses in maxilla and mini-implant, as well as maximum displacements in the mini-implant, were evaluated by a finite element method. Bivariate analysis was used to determine the optimal range of thread height and pitch.

RESULTS

Variation of thread height and pitch decreased the maximum Von Mises stresses in cortical bone, cancellous bone and mini-implant by 54.9, 78.4 and 23.6 %, respectively. The maximum displacement in the mini-implant decreased by 21.8 %.

CONCLUSION

Maxillary stress and mini-implant stability were influenced by mini-implant thread height and pitch. Increased thread height with a thread pitch of 1.20 mm was better for orthodontic mini-implant in the maxillary posterior region. Thread height played a more significant role than the thread pitch in reducing maxillary stress and enhancing orthodontic mini-implant stability.

Geometrical design characteristics of orthodontic mini-implants predicting maximum insertion torque

OBJECTIVE

To determine the unique contribution of geometrical design characteristics of orthodontic mini-implants on maximum insertion torque while controlling for the influence of cortical bone thickness.

METHODS

Total number of 100 cylindrical orthodontic mini-implants was used. Geometrical design characteristics of ten specimens of ten types of cylindrical self-drilling orthodontic mini-implants (Ortho Easy®, Aarhus, and Dual Top™) with diameters ranging from 1.4 to 2.0 mm and lengths of 6 and 8 mm were measured. Maximum insertion torque was recorded during manual insertion of mini-implants into bone samples. Cortical bone thickness was measured. Retrieved data were analyzed in a multiple regression model.

RESULTS

Significant predictors for higher maximum insertion torque included larger outer diameter of implant, higher lead angle of thread, and thicker cortical bone, and their unique contribution to maximum insertion torque was 12.3%, 10.7%, and 24.7%, respectively.

CONCLUSIONS

The maximum insertion torque values are best controlled by choosing an implant diameter and lead angle according to the assessed thickness of cortical bone.

Can cone beam CT predict the hardness of interradicular cortical bone?

Objectives

Orthodontic mini implants can be inserted at the interradicular site. The bone quality at this site may affect the stability and anchorage of the implant. Bone density is clinically evaluated by Hounsfield units (HU) obtained from cone beam CT (CBCT). The objective of this study was to determine the correlations between HU, microhardness and cortical bone thickness of interradicular site at various segments (anterior/posterior) and aspects (buccal/lingual) of both jaws in a swine model.

Materials and methods

Eight mandible and maxilla swine bones were scanned by CBCT. The HU and thickness of the above-mentioned sites were determined. Then, a Knoop microhardness test was applied and the Knoop Hardness Number was obtained (KHN).

Results

The mandible parameters spread over a wider range than the maxilla. The buccal aspect of the maxilla had higher HU and KHN values than the mandible. The lingual aspect of the mandible had higher KHN values than the maxilla. Posterior segments had higher HU and KHN values. The thickness of the alveolar cortical bone was greater in the maxilla than in the mandible. Correlations were found between HU and KHN for 3 of the 4 sites (anterior or posterior, buccal or lingual) of the mandible only. No correlations were found for the maxilla. Upon pooling the HU and KHN data for the whole jaw, correlation was found for the maxilla as well.

Conclusions

Relying on HU values as a predictor of cortical bone hardness should be considered with caution.

A comparison of tapered and cylindrical miniscrew stability

OBJECTIVES

This study compared the stability of tapered miniscrews with cylindrical miniscrews.

MATERIALS/METHODS

One hundred and five tapered and 122 cylindrical self-drilling miniscrews were placed into the maxillary and mandibular buccal alveolar areas of 132 patients (43 males and 89 females). The insertion torque and removal torque were measured and Periotest values (PTVs) were recorded at implantation.

RESULTS

The success rates of the tapered and cylindrical miniscrews examined were similar. In the maxilla, the insertion torque of the tapered miniscrews (8.3 Ncm) was significantly higher than that of the cylindrical miniscrews (6.3 Ncm) (P < 0.05). The PTVs of the tapered miniscrews were statistically significantly lower in the maxilla (P < 0.05). The removal torque values showed no significant difference between the tapered and cylindrical miniscrews in the upper and lower buccal areas (P > 0.05).

CONCLUSIONS

Tapered miniscrews had higher initial stability when compared to cylindrical miniscrews, whereas the clinical success rates and removal torques were similar between the two designs. The long-term stability is not directly affected by the miniscrew design.

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

Introduction. The aim of this study was to analyze the effects of screw design and force application on the stability of miniscrews, using RTT, SEM, and histomorphometric analyses. Materials and Methods. Eighty cylindrical, self-drilling, and Ti6Al4V alloy miniscrews (1,6 × 6 mm) were used. Four mini-screws were inserted in fibulas of each rabbit, and 115 G of force was immediately applied. Four miniscrews were inserted in the other fibula, on which no force was applied. Eight weeks after insertion, osseointegration between miniscrew and the surrounding bone was evaluated by the histomorphometric analyses, SEM, and RTT. Kruskal-Wallis and the paired t-tests were used for statistical analysis. Results. Values obtained from Group I were significantly higher than those of the other loaded groups (P < .05). There were no differences in RTT scores among Groups II, III, and IV. Similar findings were also observed for unloaded mini-screws. There was no significant difference between Groups I and I_C, while the differences between loaded and unloaded controls for each miniscrew were statistically significant. Conclusions. Immediate loading of miniscrews does not impair screw stability. Also, the diameter of miniscrew and more frequent thread pitches have a positive effect on stability; however, length of miniscrews does not have a significant effect on the stability.