Clinical factors correlated with the success rate of miniscrews in orthodontic treatment. Int J Oral Sci. 2012;4:38-44. [PMID: 22241373 PMCID: PMC3412662 DOI: 10.1038/ijos.2012.1]

Patient's Perspective on Miniscrews During Orthodontic Treatment-A Systematic Review With Meta-Analysis

During orthodontic treatment, undesirable reciprocal forces are generated during tooth movement, which explains the use of anchorage strategies to minimise their harmful effects through intra and/or extraoral appliances. Miniscrews are intraoral devices used for temporary skeletal anchorage. Miniscrews are small-sized intraoral devices used for temporary skeletal anchorage and are easy to place and remove. However, some studies refer to adverse effects such as inflammation, pain, and discomfort. This systematic review aims to synthesise the available evidence on the use of miniscrews during orthodontic treatment from the patient's perspective. The literature search was conducted using various databases MedLine through PubMed, Cochrane Library, Web of Science Core Collection, and EMBASE. A search was also carried out in the grey literature. The search terms used were "Orthodontic Anchorage Procedures," "mini-implant," "Mini Dental Implant," "Miniscrew," and "microimplant." Cochrane risk of bias tools was used to assess the quality of included studies. Patients tend to overestimate the pain inherent in this procedure. The insertion of micro implants is more accepted than the tooth extraction procedure, with less postoperative pain reported. The location, surgical technique, and type of anaesthesia used in the placement of miniscrews influence levels of discomfort. Additionally, the execution of a good surgical technique and the clinician's communication skills are factors that influence patient satisfaction and positive perception. The most frequent outcome reported is pain and discomfort, which varies depending on its location (less with mini interradicular screws than with extra-alveolar screws). Most patients are satisfied or very satisfied with this application.

The current overview of the devices of temporary anchorage placed on the palatal bone: CBCT study

Temporary anchorage devices (TADs) are frequently applied to different anatomic areas with different protocols to increase skeletal effects and anchorage in orthodontic treatment planning. It has been reported in many literatures that primary stability for orthodontic TADs is significant for long-term survival rate. For this reason, different areas of the palatal region, which has many indications, have been widely used in the studies. In this evaluation where bone quality and thickness are important, density, bone thickness, and fractal dimension (FD) on cone beam computed tomography (CBCT) will provide more predictable clinical results. The aim of this study was to evaluate bone thickness, density, and FD in the palatal region of the first, and second premolars, and first molars. There was a remarkable difference (p < 0.05) between the parameters of FD, thickness and density of bone in the identified areas in the palatal region. In terms of thickness and FD, the 1st premolar region had significantly higher values than the other regions (p < 0.05). In terms of density, the values in the right 1st molar and right 1st premolar regions were significantly higher (p < 0.05). The 1st premolar region is an ideal site for placement of palatal TADs. CBCT-assisted preliminary evaluation of FD value, bone density, and thickness may increase clinical success when selecting the location of TADs to be applied to the palatal bone.

Accuracy of Orthodontic Anchor Screw Placement Using a 3D-Printed Surgical Guide

Background Although radiographs and computed tomography (CT) images are reviewed before temporary anchorage device (TAD) implantation, implantation of TADs exactly as planned is difficult. This study aimed to evaluate the accuracy of TAD implantation using an original surgical guide fabricated using cone-beam CT data and computer-aided design software. Methodology The study participants included six experienced orthodontists who had implanted ≥20 TADs, and six inexperienced orthodontists who had never implanted a TAD. Maxillary dental typodont models with radiopaque tooth crowns and roots were used. A total of four TADs were implanted on the buccal sides: between the second bicuspid and first molars and between the first and second molars bilaterally. The accuracy of TAD implantation was examined in two groups: in 12 dental typodont models, TAD implantation was performed using a surgical guide (guide group), and in 12 dental typodont models, TAD implantation was performed without a surgical guide (freehand group). All dental typodont models implanted a total of 96 TADs. The TAD position was evaluated using the CT coordinate system and 3D image measurement software. Using the long axis of the TAD as a reference, the distance between the coronal and apical ends of the implanted TAD and those of the planned TAD, i.e., the ideal implantation position, was measured in both groups along the x, y, and z axes. The medians of the values were compared between the groups. Additionally, the presence of root contact was compared between the experienced and inexperienced orthodontists. Results On the x-axis, the linear deviations (median) of the coronal and apical ends of the TAD in the freehand group were 1.06 mm and 1.36 mm, respectively. In contrast, in the guide group, the deviations were 0.65 mm and 0.90 mm, respectively, and the difference was statistically significant (p = 0.002 and p = 0.005, respectively). On the y-axis, the deviations in the freehand group were 1.13 mm and 1.08 mm, respectively. In contrast, the deviations in the guide group were 0.71 mm and 0.79 mm, respectively, and only the coronal deviations were significantly different between the groups (p = 0.006). On the z-axis, the deviations in the freehand group were 1.44 mm and 1.86 mm, respectively. In contrast, the deviations in the guide group were 0.75 mm and 1.16 mm, respectively, and the difference was statistically significant (p = 0.006 and p = 0.002, respectively). Conclusions The use of a surgical guide allowed for more accurate TAD implantation. Additionally, TAD implantation using a guide prevented root damage.

The success rate of mini-screws for incisors intrusion and patient age, gender, and insertion angle in the maxilla using CBCT and implant-guided surgery. A split-mouth, randomized control trail

BACKGROUND AND OBJECTIVES

The intrusion of anterior teeth is a routine procedure in orthodontics, which has been performed efficiently with the help of mini-screws in the anterior region, especially the upper maxilla. This study aimed to investigate the effect of insertion angle and sociodemographic features on the success rate of mini-screws at the anterior maxillary region.

MATERIALS AND METHODS

Twenty-nine patients (18 Females and 11 Males) aged 18-40 years old were involved in the current study. A split-mouth design was carried out in which recruited patients needed bilateral anterior screws at the labial bone in the region of the incisor for the intrusion of upper anterior incisor teeth as part of their orthodontic treatment with a fixed appliance (upper right side received 90-degree insertion angle mini-screw and 45° for left side) using a surgical guide fabricated from patients CBCT and intraoral scans. The mini-screws were inserted at the attached gingiva bilaterally to achieve intrusion of upper anterior teeth with a power chain ligated from the main archwire to the anterior min-implants. The patient was recalled monthly for orthodontic appliance activation and screw assessment for 6 months. The intrusion force was 15 g on each side.

RESULTS

The results of the study showed that screw stability was higher in the male group than the female group at the 6th monthly follow-up visit with a statistically significant difference between both genders (P = .044). Concerning insertion angle, results showed a statistically significant difference between 45° and 90° as an insertion angle with a P-value <.01 in most of the follow-up months.

CONCLUSION

This study found that male patients with mini-screws inserted at 90° showed greater screw stability over time.

Insertion of orthodontic temporary anchorage devices with free gingival grafting for phenotype modification of the peri-implant mucosa

Background

Mini Implants are widely used in contemporary orthodontics, they provide skeletal anchorage even in non-compliant patients, facilitate orthodontic tooth movement, are easy to place and are relatively inexpensive. Their failure is multifactorial, and the quality of the soft tissue can present a risk limitation for the insertion of TADS. Orthodontic Mini Implants inserted in keratinized gingiva present fewer tissue-related complications and higher survival rate, than those inserted in non-keratinized mucosa. The purpose of this report is to present and describe this novel technique to modify and enhance the peri-implant mucosa of Orthodontic Mini Implants inserted in nonkeratinized gingiva.

Methods

A free gingival graft was harvested from the palate in combination with a buccal recipient site preparation in the alveolar mucosa and a TAD insertion procedure.

Results

After twenty-one days of healing, graft integration was observed. One hundred and eighty days after insertion and twelve weeks of loading, none to mild signs of clinical inflammation were documented, and the patient reported no pain or discomfort.

Conclusion

Within the limitations of this report, free gingival grafting for phenotype modification of the peri-implant mucosa, can benefit patients who need insertion of orthodontic mini-implants in non-keratinized mucosa for orthodontic tooth movement.

Three-dimensional evaluation of the cortical and cancellous bone density and thickness for miniscrew insertion: a CBCT study of interradicular area of adults with different facial growth pattern

AIM

The purpose of this study was to evaluate the effect of the density and the thickness of the cortical and the cancellous bone at selected inter-radicular areas in subjects with different facial growth patterns using cone beam computed tomography (CBCT) in order to choose the optimal area for miniscrew insertion.

MATERIALS AND METHODS

From 150 CBCT scans, 45 scans were included in the study. The subjects were categorized into three groups based on their skeletal growth pattern according to SN-GoMe angle and facial height index. Cortical and cancellous bone density and thickness were measured at the selected inter-radicular areas.

RESULTS

Compared to the other two groups, the hyperdivergent group had thinner cortical bone in the anterior region of the maxilla between the central and the lateral incisors on the buccal side at 4 mm from the alveolar crest (P-value: 0.012) and on the palatal side at 7 mm from the alveolar crest (P-value: 0.030). Cancellous bone density values in these areas were higher in subjects with hypodivergent and hyperdivergent growth pattern. Furthermore, in hyperdivergent group less dense cortical bone in the posterior region of the maxilla on the palatal side between the second premolar and the first molar (p-value: 0.020) and on the buccal side between the first molar and the second molar (p-value: 0.038 & 0.047) was observed. No significant differences were found in the mandible between the three groups. No significant differences were found between the male and the female subjects.

CONCLUSION

Hyperdivegents presented thinner cortical bone in the anterior of the maxilla between the central and the lateral incisors. Less dense cortical bone was found between maxillary second premolar and first molar on the palatal side and also between the maxillary first molar and the second molar on the buccal side in this group too. Normal showed higher density values in the posterior of the maxilla compared to the other two groups. No significant differences were found among three groups in mandible.

Effects of delayed appointments in fixed orthodontic patients due to lockdown during the COVID-19 pandemic

Objectives

To determine the frequency of orthodontic emergencies and their impact on the treatment progress caused by delayed appointments due to the lockdown during the COVID-19 pandemic.

Materials and methods

Two hundred thirty-eight patients undergoing fixed orthodontic treatment participated in this cross-sectional study. A pre-structured questionnaire was divided into six parts (Part A-C comprised of orthodontic emergencies and Part D-F comprised of various adverse effects and impacts on treatment progress). Two specialist orthodontists performed clinical examinations to complete the questionnaire. The final data were expressed as frequency and percentage.

Results

Maximum number of patients reported four months after lockdown. Nearly half of the patients reported debonding of at least one of the brackets. Loosening of molar bands and debonding of second molar tubes were observed in 12.6% and 18.9% of patients, respectively. Ligation method failures were reported in 41.2% of the patients. Patients fitted with transpalatal arch/lingual arch skeletal anchorage showed a failure rate of 26.1% and 10%, respectively. Almost 29% of the patient complained of discomfort due to distal wire impingement. Undesired tooth movements were seen in almost 25% of patients. Alignment, space closure, and settling of occlusion were affected in 47.6%, 17.4%, and 35.7% of patients, respectively.

Conclusions

This study helps to determine various types of adverse effects that can occur due to delayed appointments. The study's outcomes suggest that clinicians should be prepared to deal with future pandemics or other causes that might lead to delayed appointments.

Temporary anchorage devices in orthodontics: a bibliometric analysis of the 50 most-cited articles from 2012 to 2022

OBJECTIVES

To identify and analyze the 50 most cited articles on temporary anchorage devices (TADs) and investigate the achievement and development of scientific research about the topic through a bibliometric analysis.

MATERIALS AND METHODS

On August 22, 2022, a computerized database search was performed to detect papers published in the scientific literature about TADs from 2012 to 2022. Metrics data were identified using the Incites Journal Citation Reports (Clarivate Analytics) data set. The Scopus database was used to obtain information on the authors' affiliations, country of origin, and h-index. Key words were automatically harvested from the selected articles to implement the visualized analysis.

RESULTS

From a total of 1858 papers screened by searching the database, a list of the top 50 most cited articles was created. The total number of citations collected by the 50 most cited articles in TADs was 2380. Among the 50 most cited articles on TADs, 38 were original research papers (76.0%) and 12 were reviews (24.0%). As shown by the key word-network analysis, Orthodontic anchorage procedure was identified as the larger node.

CONCLUSIONS

Findings of this bibliometric study showed an increasing number of citations for papers on TADs, accompanied by a simultaneous rise in scientific interest in this topic in the past decade. The present work identifies the most influential articles, emphasizing the journals, the authors, and the topics addressed.

Comparative study of stress characteristics around the adjacent teeth tissues during insertion of mini-screws with different insertion angles: A three-dimensional finite element study

With a limited alveolar bone position, there is a high risk that mini-screws (MS) implants could cause damage to the adjacent teeth. To reduce this damage, the position and tilt angle of the MS must be optimized. The aim of this study was to assess the effect of MS implantation angle on the stress exerted on adjacent periodontal membrane and roots. A three-dimensional finite element model containing dentition, periodontal ligament, jaw and MS were established based on the CBCT images and MS scanning data. The MS was first inserted perpendicular to the surface of the bone at specific locations and then tilted at an angle of 10° and 20° to the mesial and distal teeth, respectively. The stress distribution in the periodontal tissue of the adjacent teeth was analyzed after MS implantation at different angles.The stress on the adjacent tooth root and periodontal ligament was most uniformly distributed when the MS was inserted vertically. It changed 9.4-97.7% when the axis of MS was tilted at 10-degree and 20-degree angles from the point of vertical insertion. The stresses experienced by the periodontal ligament and the root are similar. When the horizontal angle of the MS insertion was changed, the MS was closer to the adjacent tooth, resulting in greater stress near the PDL and root. It was recommended to insert the MS vertically into the alveolar bone surface to avoid root damage due to excessive stress.

Quantitative Evaluation of Pentraxin-3 in Peri-Miniscrew Implant Crevicular Fluid in Patients Undergoing Orthodontic Treatment: A Prospective Study

OBJECTIVE

To assess the levels of Pentraxin-3 (PTX3) in peri-miniscrew implant crevicular fluid (PMICF) before and after orthodontic force application Material and Methods: This study included 40 miniscrew implants (MSI) sites in 11 orthodontic patients with high arch discrepancy requiring first premolar extraction using maximum anchorage mechanics for the retraction of anterior teeth. After alignment, the en-masse anterior retraction was carried out using the MSI-supported direct anchorage method. PMICF was collected from the crevice of MSI using Periopaper strips 1.2µl (Oraflow Inc. USA) after one hour, 24 hours, and three weeks of MSI insertion and after one hour, 24 hours, seven days, three weeks, and six weeks of the force application. Samples were quantitatively analyzed for PTX3 levels through enzyme-linked immunosorbent assay (ELISA).

RESULTS

The trend in the change of PTX3 levels was evaluated using the Wilcoxon signed-rank test. The mean concentration of PTX3 immediately after MSI insertion was 1.19 ng/ml, significantly higher than after 3 weeks after MSI insertion (0.72 ng/ml), which may correspond to the baseline. After loading, the mean PTX3 concentration increased significantly with the peak at 24 hrs (1.28 ng/ml), followed by a gradual decline till the completion of the study (0.5 ng/ml).

CONCLUSION

After MSI insertion, a rise in PTX3 levels in PMICF suggests an underlying inflammatory process. The slow decline in PTX3 level and return to the baseline after loading suggests an adaptive bone response to the stimulus.

Investigation of periodontal status and bacterial composition aroundmini-implants

INTRODUCTION

Mini-implants are now widely used in orthodontic treatment. Soft-tissue inflammation around the mini-implant is an important factor affecting its stability. This study aimed to investigate the periodontal status and the bacterial composition around mini-implants.

METHODS

A total of 79 mini-implants in 40 patients (aged 18-45 years) were evaluated in this study. The mini-implant probing depth (mPD), mini-implant gingival sulcus bleeding index (mBI), mini-implant plaque index (mPLI), and the composition of the supragingival and subgingival plaque around the mini-implants were recorded. After Congo red staining, the bacteria were classified and counted under a light microscope.

RESULTS

The mPLI and mBI around mini-implants in the infrazygomatic crest were higher than those in the buccal shelf and interradicular area. The mPD was higher on the coronal site of the mini-implant than on the mesial, distal, and apical sites in the infrazygomatic crest. The mPLI around the mini-implant was positively correlated with the mBI, and the mBI was positively correlated with the mPD. The supragingival and subgingival bacterial composition around the mini-implants was similar to that of natural teeth. Compared with supragingival bacterial composition, the subgingival bacteria of mini-implants had a significantly lower proportion of cocci and a higher proportion of bacilli and spirochetes.

CONCLUSIONS

The bacteria composition of the plaque and the location are important factors in the inflammation around mini-implants. Similar to natural teeth, mini-implants require health maintenance to prevent inflammation of the surrounding soft tissue and maintain stability.

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.

Miniscrews for orthodontic anchorage: analysis of risk factors correlated with the progressive susceptibility to failure

INTRODUCTION

The phenomenon of orthodontic anchorage miniscrews loosening after being implanted several times happens in daily clinical practice, and the reasons need to be traced. This study aimed to investigate the underlying risk factors influencing the progressive susceptibility of orthodontic miniscrews to failure.

METHODS

Overall, 889 miniscrews were successively inserted into 347 patients because some loosened or fell off once, twice, or more before achieving their purposes. The number of miniscrew failures (ie, once, twice, or more) was defined as progressive susceptibility to failure. The clinical indicators were assessed via univariate analysis, multicollinearity diagnosis, and Poisson log-linear regression model with stepwise calculation to screen out.

RESULTS

The progressive susceptibility of miniscrews to failure was proved to be affected by the age of patients, the onset of force application, site of placement, and appliance type. Age and onset of force application presented a negative relationship with susceptibility. Miniscrews inserted in the palatal region appeared to be more stable than the forepart of the arch. In contrast, the retromaxillary and retromandibular areas obtained the lowest stability. The patients with fixed appliances were more unlikely to suffer progressive failure than removable appliances. In addition, the larger number of screws inserted in each patient, the greater probability of failure.

CONCLUSIONS

Younger people with removable appliances that miniscrews inserted in the retromaxillary or retromandibular regions and earlier onsets of loading had a higher progressive susceptibility to loosening. Meanwhile, the failure rate was elevated with the increasing number of screws per patient received.

Revisiting the Complications of Orthodontic Miniscrew

Miniscrew has been used widely as an effective orthodontic anchorage with reliable stationary quality, ease of insertion and removal techniques, immediate or early loading, flexibility in site insertion, less trauma, minimal patient cooperation, and lower price. Nonetheless, it is not free of complications, and they could impact not only the miniscrew success rate but also patients’ oral health. In this article, literature was searched and reviewed electronically as well as manually to evaluate the complications of orthodontic miniscrew. The selected articles are analyzed and subcategorized into complications during and after insertion, under loading, and during and after removal along with treatment if needed according to the time. In addition, the noteworthy associated factors such as the insertion and removal procedures, characteristics of both regional and local anatomic structures, and features of the miniscrew itself that play a significant role in the performance of miniscrews are also discussed based on literature evidence. Clinicians should notice these complications and their related factors to make a proper treatment plan with better outcomes.

Effect of Chlorhexidine Mouthwash on Gingival Health around Orthodontic Miniscrew Implants: A Pilot Placebo-Controlled Randomized Trial

OBJECTIVE

This randomized controlled trial (RCT) aims to investigate the short-term effects of chlorhexidine mouthwash (MW) on gingival health surrounding orthodontic miniscrew implants (OMIs) and their overall survivability.

MATERIALS AND METHODS

Thirty-two participants (mean age, 22.8 years) undergoing fixed orthodontic appliance treatment after maxillary premolar extraction were randomly allocated in a parallel fashion to either receive (1) MW with an active component of chlorhexidine, or (2) a placebo. Each participant received two maxillary buccal OMIs for anchorage reinforcement purposes. Participants were assessed for their gingival oral health status around all inserted OMIs and had their OMI survivability recorded at three time points; T1=1 month, T2=3 months, and T3=6 months after OMI placement. A Kaplan Meier plot was used to estimate the survival function of OMIs.

RESULTS

All randomized participants completed the follow-up period. In terms of gingival oral health, there were no statistically significant differences at any time point between the chlorhexidine MW group and the placebo-controlled group (P > 0.05). One OMI was lost in the chlorhexidine MW group and another two OMIs in the control group. There was no significant difference between both groups in terms of survivability (P = 0.585).

CONCLUSION

The use of chlorhexidine MW does not seem to have a significant clinical impact on the gingival health around OMIs or their survivability in this pilot study.

A Scoping Review about the Characteristics and Success-Failure Rates of Temporary Anchorage Devices in Orthodontics

This study synthesized the scientific evidence concerning the main characteristics of the Temporary Anchorage Devices (TADs) used in orthodontics and reported the success-failure rates during treatment. For that means, this scoping review collected articles from previous research. A complementary search was carried out in the databases PubMed-MEDLINE, Scopus, LILACS, and EMBASE, focusing on original studies published from 2010 to 2020. We analyzed the main characteristics of the publications. As a result, 103 articles were included. Most of the research was conducted among different groups, who needed TADs principally in the maxilla and an interradicular location between the second premolar and first molar. AbsoAnchor, Dentos Inc., Daegu, Korea, was the most used brand of TADs. The most common characteristics of the devices and biomechanics were a diameter and length of 1.6 mm and 8 mm, a self-drilled system, a closed technique for placement, immediate loading, and forces that ranged between 40 and 800 g. Of the studies, 47.6% showed success rates ≥90%. In conclusion, high success rates were found for TADs, and differences were found according to sociodemographic and clinical variables. The studies showed variability in methodological design, and scientific publications were concentrated in certain countries. We recommend further scientific research on TADs using more standardized designs.

New and Recovered Temporary Anchorage Devices, In Vitro Assessment of Structural and Surface Properties

The orthodontic miniscrew (TADs) is a device that is fixed into bone in the short term for the purpose of enhancing orthodontic anchorage. The aim of our study was to investigate the structural and surface properties of recovered TADs after orthodontic treatment, and compare them to new TADs. TADs (n = 15) from the same manufacturer (Absoanchor; Dentos, Daegu, Korea) were assessed; n = 10 were recovered from patients after orthodontic treatment and n = 5 were new. We performed electrochemical investigations, scanning electron microscopy (SEM) and microbiological analysis. Qualitative analysis on general electrochemical polarization revealed that the TADs retrieved from the patients provided much lower current densities in the passivity zone, and the oxidative processes taking place on their surface were of lower intensity. The surface morphologies of the tips of the retrieved mini-implants showed less sharp tips and smooth surfaces. Defects in the form of pores or cracks could be identified in both evaluated TAD groups. All retrieved TADs showed signs of biological materials (SEM analysis) and contamination on their surfaces. In conclusion, these results can assist orthodontists in comprehending the complexities of TAD behavior with respect to their design and structure.

Effect of miniscrew insertion angle in the maxillary buccal plate on its clinical survival: a randomized clinical trial

INTRODUCTION

This study sought to assess the effect of miniscrew insertion angle (vertical and oblique) on its clinical survival under shearing forces in orthodontic patients undergoing canine retraction.

MATERIALS AND METHODS

In this split-mouth randomized controlled clinical trial, 50 miniscrews were placed bilaterally in 25 patients with 45° and 90° insertion angles relative to a line perpendicular to the occlusal plane distal to the maxillary first premolar extraction site. Allocation of insertion angles to the right/left side was random using the Random Allocation Software. The patients, clinician, and statistician were blinded to the allocation of miniscrews to the side of jaw. The patients were followed-up monthly for 6 months. The primary outcome was the clinical survival of miniscrews, which was evaluated at each follow-up session. The secondary outcomes were the miniscrew stability based on the Periotest value (PTV) and the level of pain experienced by patients at 1, 12, and 24 h, and 7 days after miniscrew placement using a visual analog scale (VAS). Data were analyzed using paired t-test, repeated measures ANOVA, and McNemar's test.

RESULTS

The clinical survival rate of miniscrews placed at 90° and 45° angles was 76% and 88%, respectively. This difference was not statistically significant (P = 0.375). No significant difference was noted between the two groups regarding the PTV or the pain score either (P > 0.05).

CONCLUSION

Clinically, the insertion angle of miniscrews (90° versus 45° relative to a line perpendicular to the occlusal plane) has no significant effect on the miniscrew survival rate or stability during orthodontic treatment.

TRIAL REGISTRATION

This trial was registered at www.irct.ir ( IRCT20190901044659N1 ).

PROTOCOL

The protocol was published after trial commencement.

Stability of immediately loaded 3 mm long miniscrew implants: a feasibility study

Introduction:

Shorter miniscrew implants (MSIs) are needed to make orthodontics more effective and efficient.

Objective:

To evaluate the stability, insertion torque, removal torque and pain associated with 3 mm long MSIs placed in humans by a novice clinician.

Methods:

82 MSIs were placed in the buccal maxillae of 26 adults. Pairs of adjacent implants were immediately loaded with 100g. Subjects were recalled after 1, 3, 5, and 8 weeks to verify stability and complete questionnaires pertaining to MSI-related pain and discomfort.

Results:

The overall failure rate was 32.9%. The anterior and posterior MSIs failed 35.7% and 30.0% of the time, respectively. Excluding the 10 MSIs (12.2%) that were traumatically dislodged, the failure rates in the anterior and posterior sites were 30.1% and 15.2%, respectively; the overall primary failure rate was 23.6%. Failures were significantly (p= 0.010) greater (46.3% vs 19.5%) among the first 41 MSIs than the last 41 MSIs that were placed. Excluding the traumatically lost MSIs, the failures occurred on or before day 42. Subjects experienced very low pain (2.2% of maximum) and discomfort (5.5% of maximum) during the first week only.

Conclusions:

Shorter 3 mm MSIs placed by a novice operator are highly likely to fail. However, failure rates can be substantially decreased over time with the placement of more MSIs. Pain and discomfort experienced after placing 3 mm MSIs is minimal and temporary.

Effects of Ag-Rich Nano-Precipitates on the Antibacterial Properties of 2205 Duplex Stainless Steel

The effects of the addition of silver on the microstructural variation and antibacterial performance of 2205 duplex stainless steel after solution and aging treatment were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and antibacterial testing. The microstructure showed that 2205Ag is composed of a ferrite (α) + austenite (γ) duplex phase and Ag-rich nano-precipitates (Ag-NPs). The morphology of the Ag-NPs varied from spherical to polygonal after aging treatment at 450 °C for 4 h. These precipitates were identified as face-centered-cubic structures with a lattice parameter of a = 0.354 nm and a mismatch of δ = 0.84% relative to the austenite matrix. Notably, 2205Ag with polygonal Ag-NPs exhibited excellent antibacterial properties that were superior to those of 2205Ag with spherical Ag-NPs.

Risk factors for orthodontic mini-implants in skeletal anchorage biological stability: a systematic literature review and meta-analysis

The reason of the biological stability loss of mini-implants is still a matter of discussion between dentistry professionals. The main objective of this systematic literature review and meta-analysis was to analyze the risk factors that prejudice this loss. A search was made in the electronic databases Pubmed, Scopus, Embase and Cochrane, in addition a manual search was made too in Grey Literature (Opengrey). No limits were set on the year of publication or language. The inclusion criteria were: studies in humans treated with fixed appliances with mini-implants, where the risk factors for secondary stability were evaluated for a minimum of 8 weeks. After eliminating duplicate studies and assessing which ones achieve the inclusion criteria, a total of 26 studies were selected for the qualitative synthesis, 18 of them were included in the quantitative synthesis. Common risk variables were compared in all of them. Analyzing the forest and funnel plots, statistically significant differences were obtained only for location, the upper maxilla having lower risk than the mandible with an odds ratio of 0.56 and confidence interval of 0.39 to 0.80. Prospective studies under controlled conditions should be required in order to obtain a correct assessment of the variables analyzed.

Levels of TGF-β1 in peri-miniscrew implant crevicular fluid

The peri-miniscrew implant crevicular fluid is analogous to gingival crevicular fluid, and its contents reflect the state of inflammation and health during the life of the miniscrews in the mouth. The stability of MSI is fundamental to its role as an anchorage. This study aimed to evaluate transforming growth factor-beta one (TGF-β1) of the peri-miniscrew implant crevicular fluid (PMICF), on implant insertion, pre- and post-loading of MSIs to find a clue to their role in the stability of MSI. Fifty-two MSIs sites were placed in the mouths of 13 patients aged 12-26 years undergoing orthodontic treatment. PMICF was collected using micro-pipettes at T1 (day 0, 1 h after MSI implantation), T2 (day 1), T3/baseline (day 21, preloading of MSI), T4 (day 21, 1 h post loading), T5 (day 22, 1 day post loading), T6 (day 43, 3 weeks post loading). The levels of TGF-β1 were estimated by enzyme-linked immunosorbent assay (ELISA). The data were subjected to statistical analysis. Of the 52 MSIs, 20 MSIs failed at T3. In the case of successful MSIs, the TGF-β1 levels were found to monotonously decrease from T1 (~1400 pg/mL) until T3 (~700 pg/mL) and saturate thereafter. In the case of failed MSIs, the levels of TGF-β1 at various time periods were approximately constant and of much lower value than corresponding time periods of successful MSIs. This study highlights the role of TGF- β1 in bone metabolism around miniscrew reflecting the state of inflammation from 1 h post-implantation.

Long-term stability behavior of paramedian palatal mini-implants: A repeated cross-sectional study

INTRODUCTION

The initial stability of orthodontic mini-implants is well investigated over a period of 6 weeks. There is no clinical data available dealing with the long-term stability. The aim of this study was the assessment of long-term stability of paramedian palatal mini-implants in humans.

METHODS

Stability of 20 implants was measured after removal of the orthodontic appliance (sliding mechanics for sagittal molar movement 200 cN each side) before explantation (T4) using resonance frequency analysis (RFA). Data were compared with a matched group of 21 mini-implants assessing the stability immediately after insertion, and after 2, 4, and 6 weeks (T0-T3). The mini-implants used in this study were machined self-drilling titanium implants (2.0 × 9.0 mm). Gingival thickness at the insertion site was 1-2 mm.

RESULTS

The implant stability quotient (ISQ) values before removal of the implant at T4 were 25.2 ± 2.9 after 1.7 ± 0.2 years and did not show a statistically significant change over time compared with the initial healing group (T0-T3).

CONCLUSIONS

Comparing the stability of mini-implants just after completion of the healing period and at the end of their respective usage period revealed no significant difference. An increase of secondary stability could not be detected. The level of stability seemed to be appropriate for orthodontic anchorage.

Safe regions of miniscrew implantation for distalization of mandibular dentition with CBCT

Background

To assess the anatomy of the mandibular buccal shelf (MBS) with cone-beam computed tomography (CBCT) and to identify the region of miniscrew implantation for the distalization of mandibular dentition.

Materials and methods

The MBS was assessed in 80 patients at four regions as follows: (i) between the buccal root of the mandibular second premolar and the mesiobuccal root of the first molar (L5_b–L6_mb), (ii) between the mesiodistal root of the first molar (L6_mb–L6_db), (iii) between the distobuccal root of the first molar and the mesiobuccal root of the second molar (L6_db–L7_mb), and (iv) between the mesiodistal roots of the second molar (L7_mb–L7_db). The buccal alveolar bone thickness, the narrowest inter-radicular space at the buccal side of the roots, and the distance between the implantation site and the mandibular neural tube were measured at horizontal planes of 3, 5, 7, and 9 mm from the alveolar crest.

Results

The buccal alveolar bone thickness increased from the premolar to the molar and from the crest edge to the mandibular roots. The L7_mb–L7_db region had the thickest buccal alveolar bone of 7.61 mm at a plane of 9 mm. The buccal inter-radicular spaces were smallest in the L7_mb–L7_db region and greatest in the L6_db–L7_mb region. The distances from the implantation site to the mandibular neural tube at planes of 3, 5, 7, and 9 mm were all > 13 mm from the L6 region to the L7 region.

Conclusions

The L6_db–L7_mb region should be the first choice for miniscrew implantation in the MBS for the distalization of mandibular dentition.

Effects of low-intensity laser therapy on the stability of orthodontic mini-implants: a randomised controlled clinical trial

OBJECTIVE

To investigate the effect of low-intensity laser therapy on mini-implant stability using resonance frequency analysis during canine retraction with fixed appliances.

DESIGN

A split-mouth randomised clinical trial.

SETTING

Subjects were recruited and treated in the outpatient clinic, Department of Orthodontics, Faculty of Dentistry, Cairo University.

PARTICIPANTS

Fifteen subjects with mean age 20.9 (±3.4) years who required extraction of maxillary first premolar teeth and mini-implant-supported canine retraction.

METHODS

Thirty orthodontic mini-implants were inserted bilaterally in the maxillary arches of recruited subjects following alignment and levelling. Mini-implants were immediately loaded with a force of 150 g using nickel titanium coil springs with split-mouth randomisation to a low-intensity laser-treated side and control side. The experimental sides were exposed to low-intensity laser therapy from a diode laser with a wavelength of 940 nm at (0, 7, 14, 21 days) after mini-implant placement. Mini-implant stability was measured using resonance frequency analysis at (0, 1, 2, 3, 4, 6, 8, 10 weeks) after implant placement.

RESULTS

A total sample of 28 mini-implants were investigated with 14 in each group. Clinically, both mini-implant groups had the same overall success rate of 78.5%. There were no significant differences in resonance frequency scores between low-intensity laser and control sides from baseline to week 2. However, from week 3 to 10, the low-intensity laser sides showed significantly increased mean resonance frequency values compared to control (P > 0.05).

CONCLUSIONS

Despite evidence of some significant differences in resonance frequency between mini-implants exposed to low-intensity laser light over a 10 weeks period there were no differences in mini-implant stability. Low-intensity laser light cannot be recommended as a clinically useful adjunct to promoting mini-implant stability during canine retraction.

Success rates and factors associated with failure of temporary anchorage devices: A prospective clinical trial

AIM

The objective of the present study was to investigate success rates and associated factors affecting temporary anchorage device (TAD) failure in different biomechanical applications.

METHODS

A total of 180 TADs were used as a part of 82 patients' treatment plan (24 males and 58 females); their mean age was 21.41 years. Three types of TADs were used: 50 (3M ESPE, Neuss, Germany), 56 (Bone screw; Jeil Medical, Seoul, Korea), and 74 (Morelli, Sorocaba, Brazil). Eight maxillary and four mandibular sites were selected for insertion. Three different lengths (6, 8, and 10 mm) and three different diameters (1.5, 1.6, and 1.8 mm) were used. The force levels were set at 50, 100, 150, 200, and 250 g. Patient-, implant-, and operator-dependent factors were evaluated throughout the 266 days of function. Qualitative variables were described by proportions and percentages and analyzed using χ² test.

RESULTS

The overall success rate was 82.2%. The higher age group showed a significantly higher success rate. Oral hygiene showed a statistically-significant (P ˂ .05) difference between both success and failure groups. All other patient-related factors showed no significant differences. Regarding force levels used, the highest success rate was in 250 g and the lowest was in 100 g. There were no significant differences between both groups regarding other implant- and operator-related factors.

CONCLUSIONS

Temporary anchorage devices have a good success rate and are beneficial to be integrated in orthodontic treatment planning. Patient age, oral hygiene, and force level are the most significant factors affecting TAD success.

Primary stability and viscoelastic displacement of mini-implant system under loading

BACKGROUND

The objectives of the current study were to examine the effects of mini-implant diameters on 1) primary stability before bone properties are changed by active peri-implant bone remodeling and 2) the time-dependent displacement of mini-implant systems in bone under a functional radial loading and their associations with bone mineral density.

METHODS

Twenty one, 8mm length mini-implants (7 each for 1.4mm, 1.6mm, and 2mm diameters) were placed in mandibular sections of human cadavers (4 males and 3 females, average 69.7 (SD 13.1) years of age). Displacement of the mini-implant in wet bone was assessed during initial and subsequent continuous radial loading of 2N in the mediolateral direction for 2h. Mean, standard deviation and coefficient of variation of peri-implant bone mineral density were obtained using histograms of cone-beam computed tomography attenuation values. The cortical thickness along with the miniscrew site was also measured.

FINDINGS

The primary stability and displacement of mini-implants in bone were not significantly different between the 3 diameter groups (p>0.147, n=21). Moderate positive correlations of time-dependent viscoelastic displacement (creep) were found with bone mineral density variability independent of the mini-implant diameters (p>0.11).

INTERPRETATION

The post-implantation displacements of mini-implant suggested that the orthodontic treatment loading can develop micromotion between the mini-implant and surrounding bone leading to reduction of its primary stability. Current findings also provide an insight that peri-implant bone mineral density variability plays an important role in controlling displacement of the mini-implant, which determine its stability during early and prolonged orthodontic treatment loading periods.

Machine-driven versus manual insertion mode: influence on primary stability of orthodontic mini-implants

PURPOSE

The study aimed to explore the effect of the insertion method on maximal insertion torque as a measure of primary stability while controlling for the effect of cortical bone thickness, mini-implant length and diameter, and vertical insertion force on insertion torque.

METHODS

Six types of mini-implants (Dual Top; Jeil Medical, Corp.) with diameters of 1.4, 1.6, and 2.0 mm and lengths of 6 and 8 mm were inserted manually and in a machine-driven mode into pig rib bone samples, and experiments were repeated 10 times, which totaled 120 tested implants in 120 pig rib samples. Cortical bone thickness was measured with a sliding caliper, whereas insertion torque and vertical insertion forces were recorded with a specially designed device.

RESULTS

Significant predictors of better primary stability are thicker cortical bone (explaining 24.2% of variability), wider diameter (20.6%), manual insertion (9.9%), greater length (3.7%), higher maximal vertical insertion force (2.2%), and lower vertical force at maximal insertion torque (1.4%).

CONCLUSIONS

Manual insertion is associated with higher primary stability of orthodontic mini-implants than mechanical insertion, but thicker cortical bone and larger implant diameter seem to be stronger predictors of primary stability.

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.

Revisiting the stability of mini-implants used for orthodontic anchorage

BACKGROUND/PURPOSE

The aim of this study is to comprehensively analyze the potential factors affecting the failure rates of three types of mini-implants used for orthodontic anchorage.

METHODS

Data were collected on 727 mini-implants (miniplates, predrilled titanium miniscrews, and self-drilling stainless steel miniscrews) in 220 patients. The factors related to mini-implant failure were investigated using a Chi-square test for univariate analysis and a generalized estimating equation model for multivariate analysis.

RESULTS

The failure rate for miniplates was significantly lower than for miniscrews. All types of mini-implants, especially the self-drilling stainless steel miniscrews, showed decreased stability if the previous implantation had failed. The stability of predrilled titanium miniscrews and self-drilling stainless steel miniscrews were comparable at the first implantation. However, the failure rate of stainless steel miniscrews increased at the second implantation. The univariate analysis showed that the following variables had a significant influence on the failure rates of mini-implants: age of patient, type of mini-implant, site of implantation, and characteristics of the soft tissue around the mini-implants. The generalized estimating equation analysis revealed that mini-implants with miniscrews used in patients younger than 35 years, subjected to orthodontic loading after 30 days and implanted on the alveolar bone ridge, have a significantly higher risk of failure.

CONCLUSION

This study revealed that once the dental surgeon becomes familiar with the procedure, the stability of orthodontic mini-implants depends on the type of mini-implant, age of the patient, implantation site, and the healing time of the mini-implant. Miniplates are a more feasible anchorage system when miniscrews fail repeatedly.

Effect of healing time on bone-implant contact of orthodontic micro-implants: a histologic study

Objectives. This study aimed to evaluate the effect of immediate and delayed loading of orthodontic micro-implants on bone-implant contact. Materials and Methods. Sixty four micro-implants were implanted in dog's jaw bone. The micro-implants were divided into loaded and unloaded (control) groups. The control group had two subgroups: four and eight weeks being implanted. The loaded group had two subgroups of immediate loading and delayed (after four weeks healing) loading. Loaded samples were subjected to 200g load for four weeks. After sacrificing the animals micro-implants and surrounding tissues were observed histologically. Bone-implant contact ratios (BIC) were calculated and different groups' results were compared by three-way ANOVA. Results. Mean survival rate was 96.7% in general. Survival rates were 96.7%, 94.4% and 100% for control, immediate and delayed loaded groups, respectively. BIC values were not significantly different in loaded and control groups, immediate and delayed loading groups, and pressure and tension sides. Mandibular micro-implants had significantly higher BIC than maxillary ones in immediate loading, 4-weeks control, and 8-weeks control groups (P = 0.021, P = 0.009, P = 0.003, resp.). Conclusion Immediate or delayed loading of micro-implants in dog did not cause significant difference in Bone-implant contact which could be concluded that healing time had not significant effect on micro-implant stability.

Microbial colonization in orthodontic mini-implants

Peri-implant inflammation contributes for loss of secondary stability of orthodontic mini-implants. The investigation of microbial colonization in this area would benefit its control, and consequently favor the long-term success of mini-implants. Therefore, the aim of this study was to determine the establishment and the evolution of microbial colonization process in orthodontic mini-implants for 3 months, since the time of their installation. One-hundred and fifty samples collected from 15 mini-implants were investigated from baseline up to 3 months. The biological material was obtained from peri-implant area using paper points. Nonspecific, Streptococcus spp, Lactobacillus casei and Candida spp colonizations were analyzed by cell growth methods. Porphyromonas gingivalis colonization was observed by 16S rDNA-directed polymerase chain reaction. Data from cell growth were submitted to the Wilcoxon sign rank test and results from molecular analysis were presented in a descriptive way. There was no significant difference in the microbial colonization among the examined time intervals, except for Streptococcus spp, between baseline and 24 h, which characterized the initial colonization in this time interval. Lactobacillus casei and Candida spp colonizations were insignificant. No Porphyromonas gingivalis was detected among the analyzed samples. The microbial colonization of mini-implants did not significantly change during the study. However, it should be monitored by orthodontists, since it is an important factor for mini-implants success.

Evaluation of factors affecting the success rate of orthodontic mini-implants by survival analysis

AIM: To investigate the success rate of mini-implants and its characteristics and risk factors by survival analyses.

METHODS: Three hundred and ninety-four mini-implants of the same type were placed by a single clinician. Age, gender, treatment duration, time of failure, side and jaw of implantation and the soft tissue at placement site were recorded. Odds ratio, survival curves, and Cox proportional hazard model were applied to evaluate the factors influencing the mini-implants’ success rate.

RESULTS: The cumulative success rate was 88.1%. The maxilla had a significantly higher success rate than that of the mandible (91.7% vs 83.7%, respectively, P = 0.019). Placement of mini-implants in the attached gingiva (AG) showed a higher success rate than that of the mucogingival junction (MGJ) and mucous membrane (MM) (AG, 94.3%; MGJ, 85.8%; MM, 79.4%; P < 0.001). Significant association was found between the jaw and the gingival tissue type (P < 0.001). There were no significant differences between maxilla and mandible when compared within each placement site.

CONCLUSION: The gingival tissue type had the most significant effect on the success rate of the mini-implant with higher success rate in the attached gingiva.

Accuracy of miniscrew surgical guides assessed from cone-beam computed tomography and digital models

INTRODUCTION

Several methods are available to enhance the precision of miniscrew placement. The use of surgical guides based on cone-beam computed tomography is indicated especially in patients with risky or difficult anatomic situations. The purpose of this study was to evaluate the accuracy of miniscrew placement by using surgical guides developed with computer-aided design and manufacturing techniques.

METHODS

Miniscrews were placed in cadaver maxillae using stereolithographic computer-aided design and manufacturing techniques with assistance from surgical guides (surgical guide group, n = 25) or periapical x-rays (control group, n = 20). Insertion sites were selected using a 3-dimensional surgical planning program by fusing maxillary digital model images and cone-beam computed tomography images. Deviations between actual and planned placements were measured as 3-dimensional angular deviations and distance (coronal and apical) deviations.

RESULTS

In the surgical guide group, the angular deviation was a median of 3.14° (range, 1.02°-10.9°), and the mesiodistal deviations in the coronal and apical areas were medians of 0.29 mm (range, 0.03-0.73 mm) and 0.21 mm (range, 0.03-0.97 mm), respectively. The deviations differed significantly between operators in the control group, but not in the surgical guide group. In the surgical guide group, there was no root damage from miniscrew placement, and 84% of the miniscrews were placed without contacting adjacent anatomic structures. In the control group, 50% of the miniscrews were placed between the roots (P <0.05).

CONCLUSIONS

Surgical guide accuracy was improved when digital model imaging was used. Miniscrews were placed more accurately when using surgical guides than when using a direct method.

Orthodontic implants: concepts for the orthodontic practitioner

Orthodontic implants have become a reliable method in orthodontic practice for providing temporary additional anchorage. These devices are useful to control skeletal anchorage in less compliant patients or in cases where absolute anchorage is necessary. There are a great number of advantages in this new approach which include easy insertion, decreased patient discomfort, low price, immediate loading, reduced diameter, versatility in the forces to be used, ease of cleaning, and ease of removal. However, a proper management of the screws by the practitioner is necessary in order to increase the success rate of the technique. The purpose of this paper is to update practitioners on the current concepts of orthodontic implants and orthodontic mechanics.