Miniscrews in orthodontic treatment: Review and analysis of published clinical trials

The Orthodontic Mini-Implants Failures Based on Patient Outcomes: Systematic Review

Anchorage is a challenge and essential issue for an orthodontist in determining the success of orthodontic treatment. Orthodontic anchorage is defined as resistance to unwanted tooth movement. Mini-implant is one of the devices that can be used as an anchor in orthodontic treatment. Many cases have reported successful treatment using mini-implant, but there are cases where mini-implants may fail. Failure of mini-implants can affect orthodontic treatment, and it is known that several factors may lead to mini-implant loss in orthodontic treatment. This systematic review aimed to determine the factors influencing mini-implant failure in orthodontic treatment. Articles were selected from electronic databases (PubMed, Google Scholar, The Cochrane Library, ScienceDirect) from January 2015 until 2023 according to the PRISMA method (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) under the PEOS (Population-Exposure-Outcome-StudyType) framework questions for systematic review. The study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42022337684). All data collected were in English, and filtering was done by eliminating duplicate data, meta-analysis, case reports, case series, mini-reviews, and animal studies. The analysis was further divided into three groups, that is, patient-related, implant-related, and operator-related and operator-related (A graphical abstract provided as a Supplementary information [available in the online version]). Twenty-one articles were identified according to the inclusion criteria in the form of retrospective, prospective, in vivo, and randomized controlled trial studies. Mini-implant failures due to patient-related showed six etiological factors, failures due to implant-related had eight etiological factors, and only one factor was operator-related, which may lead to mini-implant failure. The data was extracted without a computerized system and only in English. Mini-implant failure can be caused by many factors; we could not accuse one major factor as a cause. However, the quality or condition of the bones and oral hygiene are factors that play a significant role in obtaining the stability of implants. Mini-implant failure is highly influenced by poor oral hygiene and peri-implant inflammation. Comprehensive diagnostic prior to mini-implant insertion should be appropriately considered. This systematic review describes several factors that can influence mini-implant failure, divided into three groups: patient-related, implant-related, and operator-related (A graphical abstract provided as a Supplementary information [available in the online version]).

Retrospective evaluation of the success rate and factors associated with the stability of alveolar ridge orthodontic miniscrews: Pilot study

BACKGROUND

An uncommon location for placing miniscrews, used to provide anchorage control in various tooth movements, is the alveolar ridge. This study aimed to provide an evaluation of the success rate of alveolar ridge miniscrews and examine variables that might impact their success.

METHODS

Charts for 295 patients who had miniscrews were screened. Twenty patients (5 male and 15 female: average age = 38.15 ± 15.10 years) with a total of 50 alveolar ridge miniscrews were analyzed. A customized data form was used to collect patients' and miniscrews' related variables. Kaplan-Meier estimator was used for the survival function, whereas Cox proportional hazards regression models were used to associate collected variables with alveolar ridge miniscrew survival.

RESULTS

In total, 31 (62.0%) miniscrews were stable and 19 (38.0%) failed. The survival time for those that failed was 6.03 ± 7.08 months. The follow-up period for those that survived was 35.84 ± 19.47 months. Male gender versus female (hazard ratio [HR] 2.46; 95% confidence interval [CI] 1.35-4.48; P = 0.003), and if the miniscrew was a replacement versus non-replacement (HR 0.27; 95% CI 0.07-0.99; P = 0.048) influenced the survival. Additionally, miniscrews that were used for both indirect and direct or indirect anchorage alone plus those with evidence of splinting showed a 100% survival rate, which led to an HR 0 (P < 0.001). When the previously mentioned variables were modeled, none seemed to have a significant effect on failure except for splinting and type of anchorage (P < 0.001), because none of the splinted miniscrews failed.

CONCLUSIONS

The failure rate of alveolar ridge miniscrews was (38.0%) over 6.03 ± 7.08 months. The survival rate was (62.0%) over 35.84 ± 19.47 months. The evidence of splinting and the type of anchorage had a significant effect on survival probability.

Functionality testing of an innovative biomechanically optimized and surface-modified orthodontic mini-screw-a comparative study

PURPOSE

The failure rate of orthodontic mini-screws depends strongly on primary stability and, thus, on insertion torque. Further improvement regarding the failure rate might be achieved by modifying the surface coating. Therefore, the aim of the study was to investigate the stability of a newly designed and surface-modified orthodontic mini-screw in beagle dogs.

METHODS

Newly designed mini-screws coated either with DOTIZE® or DOTIZE®-copper (DOT GmbH, Rostock, Germany; each: n = 24) were inserted in the mandibles of eight beagle dogs for a duration of 8 months. Insertion and removal torque were measured. These data were compared to values generated by using the artificial bone material Sawbones® (Sawbones Europe AB, Malmö, Sweden). Experiments with and without torque limitation (each: n = 5) were run. The bone-to-implant contact rate and the amount of bone between the threads were examined. Statistical significance was set at P < 0.05.

RESULTS

The success rates of the in vivo study reached high levels with 95.3% for the DOTIZE-coated and 90.5% for the DOTIZE-copper-coated screws, whereas the insertion and removal torque did not differ between the coatings. During insertion, a torque limitation of 20 Ncm was necessary to ensure that the recommended limit was not exceeded. The insertion in Sawbones without torque limitation revealed a significantly higher torque compared to torque-limited insertion (18.2 ± 1.3 Ncm, 23.6 ± 1.3 Ncm). Bending occurred (n = 5) in the thread-free part of the mini-screw.

CONCLUSIONS

Surface coating might be able to improve the performance of orthodontic mini-screws. The study showed high success rates and stable mini-screws until the end of observation. Further investigations are necessary.

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.

Vertical changes in the hard tissues after space closure by miniscrew sliding mechanics: a three-dimensional modality analysis

OBJECTIVES

This study aimed to investigate vertical changes in the maxillary central incisor and the maxillary first molar, along with alterations in the mandibular plane angle during space closure using miniscrew sliding mechanics.

METHODS

Twenty adult patients treated at Peking University Hospital of Stomatology between 2008 and 2013 were included. Digital dental models and craniofacial cone-beam computed tomography (CBCT) scans were obtained at the start of treatment (T0) and immediately after space closure (T1). Stable miniscrews were used for superimposing maxillary digital dental models (T0 and T1), and vertical changes in the maxillary first molar and the maxillary central incisor were measured. Three-dimensional changes in the mandibular plane were assessed through CBCT superimposition.

RESULTS

The maxillary central incisor exhibited an average extrusion of 2.56 ± 0.18 mm, while the maxillary first molar showed an average intrusion of 1.25 ± 1.11 mm with a distal movement of 0.97 ± 0.99 mm. Additionally, the mandibular plane angle decreased by an average of 0.83 ± 1.65°. All three indices exhibited statistically significant differences.

CONCLUSION

During space closure using the miniscrew sliding technique, significant changes occurred in both the sagittal and vertical dimensions of the upper dentition. This included extrusion of the maxillary central incisors, intrusion of the maxillary first molars, and a slight counterclockwise rotation of the mandibular plane.

Assessment of the efficacy of various maxillary molar intrusion therapies: a systematic review

AIMS

To systematically assess the efficacy of the various interventions used to intrude maxillary molars. Furthermore, to evaluate associated root resorption, stability of intrusion, subsequent vertical movement of mandibular molars, cost effectiveness, compliance, patient reported outcomes and adverse events.

METHODS

A pre-registered and comprehensive literature search of published and unpublished trials until March 22nd 2023 with no language restriction applied in PubMed/Medline, Embase, Scopus, DOSS, CENTRAL, CINAHL Plus with Full Text, Web of Science, Global Index Medicus, Dissertation and Theses Global, ClinicalTrials.gov, and Trip (PROSPERO: CRD42022310562). Randomized controlled trials involving a comparative assessment of treatment modalities used to intrude maxillary molars were included. Pre-piloted data extraction forms were used. The Cochrane Risk of Bias tool was used for risk of bias assessment, and The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used for certainty of evidence appraisal.

RESULTS

A total of 3986 records were identified through the electronic data search, of which 24 reports were sought for retrieval. Of these, 7 trials were included. One trial was judged at high risk of bias, while the others had some concerns. Based on individual small sample studies, maxillary molar intrusion was achieved using temporary anchorage devices (TADs) and rapid molar intruder appliance (RMI). It was also observed to a lesser extent with the use of open bite bionator (OBB) and posterior bite blocks. The molar intruder appliance and the posterior bite blocks (spring-loaded or magnetic) also intruded the lower molars. Root resorption was reported in two studies involving TADs. None of the identified studies involved a comparison of conventional and TAD-based treatments for intrusion of molars. No studies reported outcomes concerning stability, cost-effectiveness, compliance and patient-reported outcomes. Insufficient homogeneity between the included trials precluded quantitative synthesis. The level of evidence was very low.

CONCLUSIONS

Maxillary molar intrusion can be attained with different appliances (removable and fixed) and with the use of temporary anchorage devices. Posterior bite blocks (spring-loaded or magnetic) and the RMI offer the additional advantage of intruding the mandibular molars. However, stability of the achieved maxillary molar intrusion long term is unclear. Further high-quality randomized controlled trials are needed.

Feasibility of mini-implant insertion between mesial and distal buccal roots of a maxillary first molar: A cone-beam computed tomography imaging study

INTRODUCTION

Mini-implant insertion in the maxillary posterior region can be influenced by anatomic limitations, thus increasing the failure rate. We explored the feasibility of a new implantation site: the region between the mesial and distal buccal roots of the maxillary first molar.

METHODS

Cone-beam computed tomography data from 177 patients were collected from a database. The maxillary first molars were morphologically classified by analyzing the angle and morphology of the mesial and distal buccal roots. Next, 77 subjects were randomly selected from the 177 patients to measure and analyze the hard-tissue morphology in the maxillary posterior region.

RESULTS

We devised the Morphological Classification on the Mesial and Distal Buccal Roots of Maxillary First Molar (MCBRMM), divided into 3 types: MCBRMM-I, II, and III. In all subjects, MCBRMM-I, II, and III accounted for 43%, 25%, and 32%, respectively. At 8 mm from the mesial cementoenamel junction of maxillary first molars, the interradicular distance between the maxillary first molar's mesiodistal buccal roots of MCBRMM-I was 2.6 mm, showing an upward trend from the cementoenamel junction to the apex. The distance from the buccal bone cortex to the palatal root was >9 mm. The buccal cortical thickness was >1 mm.

CONCLUSIONS

This study provided a potential site for mini-implant insertion in the maxillary posterior region: the alveolar bone of maxillary first molars in MCBRMM-I.

Comparison of mechanical stability of mini-screws with resorbable blasting media and micro-arc oxidation surface treatments under orthodontic forces: An in vitro biomechanical study

INTRODUCTION

The aim of this study was to compare the primary stability of mini-screws with different surface treatments such as resorbable blasting media (RBM) and micro-arc oxidation (MAO) under in vitro orthodontic forces.

MATERIAL AND METHODS

Thirty-six self-drilling TiAl6V4-ELI grade 23 titanium alloy 1.6×8mm mini-screws were inserted into polyurethane foam blocks and divided into three groups according to surface properties: machine surface (MS), RBM-treated, and MAO-treated. An orthodontic force of 150g was applied to the mini-screws using NiTi coils. Maximum insertion torque (MIT) and maximum removal torque (MRT) were measured with a digital torque screwdriver during insertion and removal. For each mini-screw, stability measurements were made with the Periotest M device at day 0 and weeks 1, 2, 4, 8, and 12.

RESULTS

Significant differences in MIT were observed between all groups in pairwise comparisons (P<0.001) with the highest value in the MAO-treated group and the lowest in the MS group. The mean MRT values differed in all three groups (P=0.001). In pairwise comparisons of MRT, only the difference between MS group and RBM-treated group was significant. The highest value was observed in the RBM-treated group, while the lowest value was observed in the MS group. Periotest values were significantly higher in the MAO-treated group than the RBM-treated group at weeks 8 and 12. A positive significant correlation was found between MIT and MRT in all groups. No significant correlation was found between MIT, MRT and Periotest values in all groups.

CONCLUSION

RBM-treated group was significantly higher than the MS group in MIT and MRT values. According to Periotest values, RBM-treated group was found to be significantly more stable than the MAO-treated group at weeks 8 and 12. Therefore, RBM surface treatment was found to be more favourable than other surfaces to increase success rate in clinical applications.

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.

International investigation on temporary anchorage device use: A survey of orthodontists

BACKGROUND

This study investigates characteristics of temporary anchorage devices (TADs) use by surveying a sample of international orthodontists. Furthermore, the survey investigates the stability, insertion technique, and failure rate of TADs and professionals' experience in residency, and it also attempts to establish guidelines for its use in everyday practice.

METHODS

A 19-question survey was sent to orthodontists worldwide asking opinion-based, case-specific, and placement technique questions regarding TADs. Results were collected from 251 survey respondents. The country/regions of practice and length of time practicing orthodontics were the independent variables.

RESULTS

Survey respondents indicated that most orthodontists rarely or sporadically use TADs. Significant differences were also found for TAD utilization purposes, sizes, and placement techniques among different countries/regions and for failure rates (1 or more of the last 6 TADs placed failed-61.6%). A significant difference was found in how many TADs orthodontists placed in residency versus private practice (56% vs. 15%) in relation to how long they have been practicing, but it did not greatly affect the frequency of use, mechanics, or placement technique.

CONCLUSIONS

The frequency of TAD use is similar in many different countries and among different age groups. Although the collected responses suggested significant differences among respondents from different countries, the variability of results for TAD use worldwide prevent the establishment of clear guidelines.

Comparison of 3 different bone-borne type expansion appliances used in surgically-assisted rapid palatal expansion: A finite element analysis

INTRODUCTION

This study aimed to compare the effects of 3 different bone-borne type expansion appliances used in the surgically-assisted rapid palatal expansion (SARPE) by finite element analysis.

METHODS

Three different miniscrew-supported palatal expansion appliances were modeled. Median and lateral osteotomies were performed without pterygomaxillary suture separation. Model I consisted of a palatal expander with 2 miniscrews placed 4 mm far from the midpalatal suture. In model II, 2 miniscrews were located at the alveolar ridge between the first molar and the second premolar. In model III, 4 miniscrews were placed as a combination of the first and second models. Stress distributions and amount of displacements were evaluated with Ansys software (version 19.2; Ansys, Canonsburg, Pa) for 5-mm expansion in a symmetrical finite element analysis model to reflect the clinical situation.

RESULTS

SARPE simulation using miniscrew-assisted maxillary expanders for all models showed a rotation and tipping of the maxilla. The largest displacement was found for the anterior part of the palate in model II and the posterior part in model III. Although a wedge-shaped expansion pattern was observed in all models, this form was more prominent in model II. The highest stress value (0.91 MPa) was measured in model I, and the lowest value (0.004 MPa) was measured in model II for the anterior nasal spine region. The highest stress value (0.51 MPa) was measured in model III, and the lowest value (0.12 MPa) was measured in model II for the posterior nasal spine region. The lowest stress values were measured in model II for all the craniofacial and maxillofacial structures.

CONCLUSIONS

Among the models, the lowest stress distribution conditions for craniofacial and maxillofacial structures were found in model II. The largest displacement was found at the incisors and anterior part of the maxilla for model II. The greatest displacement was found at the posterior region for model III.

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.

Microbiological Advances in Orthodontics: An Overview and Detailed Analysis of Temporary Anchorage Devices

Dental biofilm is the initiating factor of oral diseases, such as periodontitis and caries. Orthodontic treatment could alter the microbiome structure balance, and increase the risk of such diseases. Furthermore, fixed appliances can induce temporary changes in the microbiome community, and the changes that clear aligners bring are smaller by comparison. Temporary anchorage devices (TADs) are skeletal anchorages that are widely used in orthodontic treatment. Microorganisms affect the occurrence and development of inflammation surrounding TADs. At present, existing researches have verified the existence of plaque biofilm on the surface of TADs, but the formation of plaque biofilm and plaque composition under different stable conditions have not been fully understood. The development of high-throughput sequencing, molecular biology experiments, and metabonomics have provided new research ideas to solve this problem. They can become an effective means to explore the microbiome surrounding TADs.

Effects of Rigid and Nonrigid Connections between the Miniscrew and Anchorage Tooth on Dynamics, Efficacy, and Adverse Effects of Maxillary Second Molar Protraction: A Finite Element Analysis

Introduction

Direct, rigid indirect, and nonrigid indirect absolute anchorages using temporary anchorage devices (TADs, mini-implants/miniscrews) can provide promising opportunities for challenging, yet common, orthodontic tooth movements such as molar protraction. Rigid rectangular wire and ligature wire are the most common methods of attaching a tooth to a miniscrew in indirect anchorages. We aimed to provide a comparison of the rigidity of the connecting wire in terms of stress on the miniscrew, the anchorage loss, and the risk of root resorption using finite element analysis (FEA).

Methods

The maxillary right second molar was protracted into the proximal space at a 150 g load (1) using direct absolute anchorage with a tapered miniscrew implanted between the premolar roots and using indirect absolute anchorage with the second premolar reinforced by the miniscrew through (2) a rigid stainless steel (SS) wire or (3) a nonrigid SS ligature wire (4) at different elastic moduli. Stresses and displacements of 4 models' elements were measured. The risk of external root resorption was evaluated.

Results

Connecting the tooth to the miniscrew using rigid full-size wire (model 2) compared to ligature (model 3) can give better control of the anchorage (using the ligature wire, the anchorage loss is 1.5 times larger than the rectangular wire) and may reduce the risk of root resorption of the anchorage unit. However, the risk of miniscrew failure increases with a rigid connection, although it is still lower than with direct anchorage. The miniscrew stress when using a ligature is approximately 30% of the rigid model using the rectangular wire. The miniscrew stress using the rectangular wire is approximately 82.4% of the miniscrew stress in the direct model. Parametric analysis shows that the higher the elastic modulus of the miniscrew-tooth connecting wire in the indirect anchorage, the less the anchorage loss/palatal rotation of the premolars/and the risk of root resorption of the anchorage teeth and instead the stress on the miniscrew increases.

Conclusions

Direct anchorage (followed by rigid indirect anchorage but not nonrigid) might be recommended when the premolars should not be moved or premolar root resorption is a concern. Miniscrew loosening risk might be the highest in direct anchorage and lowest in nonrigid indirect anchorage (which might be recommended for poor bone densities).

Risk of root damage after using lateral cephalogram and intraoral scan for guided insertion of palatal miniscrews

Background

Guided insertion of palatal miniscrews using a lateral cephalogram instead of cone beam computed tomography (CBCT) significantly reduces the radiation level for the patient. Till now no data are available on the risk of hitting the incisors in this regard, which is one of the worst clinical complications when inserting a paramedian miniscrew. Hence, this study aims to investigate the distance between the mini-implant and the roots of the central and lateral incisors.

Methods

Lateral cephalogram, an intraoral scan, and CBCT of 20 patients were superimposed. After a miniscrew (1.7 × 8 mm) placement based on intraoral scan and lateral cephalogram, the CBCT was used as control for the distance between the miniscrews and the roots of the incisors.

Results

The mean value of the shortest distance between the miniscrew and roots of the incisors in the lateral cephalogram was 4.74 ± 1.67 mm. The distance between both miniscrews and the central incisors measured in the CBCT was 5.03 ± 2.22 mm and 5.26 ± 2.21 mm and between the two miniscrews and the lateral incisors was 4.93 ± 1.91 mm and 5.21 ± 2.64 mm. No significant differences between the distances in the CBCT and the lateral cephalogram could be observed. In one case, the CBCT control revealed the penetration of two palatally displaced canines after insertion based on intraoral scan and lateral cephalogram.

Conclusions

The use of an intraoral scan and a lateral cephalogram for guided paramedian insertion of palatal miniscrews can prevent incisor root damage. This may reduce the radiation since no CBCT seems necessary. The current investigation focuses on the anterior paramedian area of the palate. Outside that region and in complex cases with displaced teeth in the palatal area, a CBCT might be indicated.

Accuracy of the digital workflow for guided insertion of orthodontic palatal TADs: a step-by-step 3D analysis

Background

The introduction in the orthodontic field of the digital workflow for guided insertion of palatal TADs and the development of the 1-visit protocol led to the reduction of chair time and the possibility of complete customization of designs and materials. Conversely, the reduction of operative steps implicates a lower tolerance of deviations between the planned and the actual position of the miniscrews, particularly when the orthodontic device is fixed on 4 palatal TADs or has a rigid structure. This study aims to analyze the influence of each step of the digital workflow on the deviation of the miniscrews’ axis of insertion in a bicortical sample. The null hypothesis is that there are no significant differences in the deviations among the operative steps.

Methods

33 subjects were selected for insertion of bicortical palatal miniscrews with a 1-visit protocol. Digital files were collected at the three stages of the workflow (i.e., digital planning, laboratory prototype, post-insertion impression). A 3D software analysis was performed on a total of 64 miniscrews. After automatic shape recognition of the guiding holes of the digital plan and the scanbodies of the laboratory prototype and post-insertion impression as geometric cylinders, their three-dimensional longitudinal axis was traced and the deviation among them was calculated. Friedman test with Bonferroni correction was performed to assess the significance of the deviations among the three steps, with significance set at p < 0.05.

Results

The laboratory step has a significantly lower degree of deviations (2.12° ± 1.62) than both the clinical step (6.23° ± 3.75) and the total deviations (5.70° ± 3.42). No significant differences were found between miniscrews inserted on the left or the right side.

Conclusions

This study suggests that laboratory procedures such as surgical guide production or rapid prototyping don’t play a significant role in the degree of deviations between the planned and the positioned palatal TADs. Conversely, the clinical steps have a bigger influence and need to be carefully evaluated. Despite this difference, there is a cumulative effect of deviations that can lead to the failure of the 1-visit protocol.

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.

Success rate of infrazygomatic miniscrews considering their design and insertion techniques. A review

Miniscrews offer the possibility of performing dental movements, minimizing unwanted side effects and enhancing effectiveness. Extra-alveolar miniscrews are ideal as they provide excellent primary stability and avoid anatomical structures. However, in some cases the primary stability is lost before achieving the success of the mechanics used and thus, the most likely causes of failure should be determined. The purpose of this review was to analyze the success rate of infrazygomatic miniscrews, considering their design and the insertion techniques used. Data collection of this literature review was carried out by searching PubMed, Wiley, Google Scholar sites, SCIELO, Elsevier and Dialnet for publication made from 2003 to June 2022. The search was carried out on June 10th, 2022 and the following keywords were used; infrazygomatic crest, miniscrews, anchorage and stability. Different topics were analyzed and discussed highlighting their clinical relevance. After analyzing the 798 articles, 566 were excluded. The remaining articles were re-analyzed and 153 articles were excluded for the title or abstract and 33 articles were excluded for the methodology. Finally, 46 items remained. After thoroughly analyzing all the articles included, this study concluded that the alloy of the miniscrew (stainless steel or titanium), perforation of the maxillary sinus and the placement area (adhered mucosa or mobile mucosa) do not influence the survival of the miniscrew. The evidence also indicates that the percentage of failure is lower in infrazygomatic compared to intraradicular miniscrews. Orthodontists can confidently and safely include infrazygomatic miniscrew in different orthodontic procedures.

Failure Rate of Orthodontic Mini-screw after Insertion using 3D Printed Guide versus Conventional Free Hand Placement Technique: Split Mouth Randomized Clinical Trial

AIM: The aim of the study is to assess the failure rate after mini-screw insertion using digital three-dimensional printed guide versus free hand placement technique through a well-designed split-mouth randomized clinical trial. METHODS: Forty-two patients with mean age (22.56 ± 3.47 years) indicated for upper first premolars’ extraction (Bimaxillary protrusion and Class II division 1) were included in the study. Their maxillary quadrants were randomized to receive mini-screws as means of anchorage. Pre-operative maxillary cone-beam computed tomography scan with ultra-low-dose protocol was imaged and the maxillary arch was scanned using intra-oral scanner to obtain stereo-lithographic format file for the maxillary arch. Using in vivo and Rapidform Geomagic Studio® _Softwares the mini-screws were planned to be inserted in the buccal inter-radicular space between the upper second premolar and first molar in both right and left sides. For the intervention sides; digital three-dimensional guides were designed and printed for mini-screw insertion. Failure of the mini-screws was assessed till 3 months of loading. RESULTS: There was no statistical significant difference in failure rate of mini-screws in both intervention (7.14%) and control sides (16.6%), with weak and moderate correlation between the root proximity and the mini-screws failure in intervention and control groups respectively. CONCLUSIONS: Using a digital three-dimensional printed guide for mini-screw insertion had no effect on the failure rate of the inserted mini-screws. REGISTRATION: ClinicalTrials.gov Identifier: NCT03653078.

Construction of Customized Palatal Orthodontic Devices on Skeletal Anchorage Using Biomechanical Modeling

Orthodontic implants have been developed for the implementation of skeletal anchorage and are effectively used in the design of individual orthodontic devices. However, despite a significant amount of clinical research, the biomechanical aspects of the use of skeletal anchorage have not been adequately studied. The aim of this work was to numerically investigate the stress-strain state of the developed palatal orthodontic device supported by mini-implants. Four possible options for the placement of mini-implants in the bone were analyzed. The effect of a chewing load of 100 N on the bite plane was investigated. The study was carried out using biomechanical modeling based on the finite element method. The installation of the palatal orthodontic device fixed on mini-implants with an individual bite plane positioned on was simulated. The dependence of equivalent stresses and deformation changes on the number and location of the supporting mini-implants of the palatal orthodontic device was investigated. Two materials (titanium alloy and stainless steel) of the palatal orthodontic device were also investigated. The choice of a successful treatment option was based on the developed biomechanical criteria for assessing the surgical treatment success. Application of the criteria made it possible to estimate the stability and strength of fixation of each of the considered mini-implants installation options. As a result, options for the mini-implants optimal placement were identified (the first and the fourth which provide distributed front and side support of the device), as well as the preferred material (titanium alloy) for the manufacture of the palatal orthodontic device.

Analysis of biological and structural factors implicated in the clinical success of orthodontic miniscrews at posterior maxillary interradicular sites

OBJECTIVE

This study aims to evaluate success factors implicated in clinical orthodontic miniscrew stability after their interradicular placement in maxilla.

MATERIALS AND METHODS

Six hundred seventy-six miniscrews were inserted in maxillary interradicular sites in a sample of 276 patients (109 males and 167 females; mean age 19 ± 1.7 years) and immediately loaded. Percentage failure rate was recorded, and the influence of the following factors was investigated: structural (miniscrew length, diameter and body shape), operative (side of insertion site, pilot hole drilling or not) and biological (maximal insertion torque [MIT] and type of gingiva). A chi-square test with Monte Carlo correction was performed to detect the influence of these variables on the failure rate of orthodontic miniscrews. Then both multivariate logistic regression and post hoc analysis were performed, followed by classification and regression tree (CART) analysis.

RESULTS

The average success rate was 88%. The principal factors implicated in the failure rate were miniscrew length, MIT values and type of gingiva. Specifically, 8 mm miniscrew length, alveolar mucosa and 5-10 Ncm MIT values were linked to higher failure rates. According to CART, the main variable influencing failure is miniscrew length (≤ 8 mm for higher failure rates). For others, MIT values of 5-10 Ncm are linked to higher failure rates (p < 0.05).

CONCLUSION

Orthodontic miniscrews inserted in the maxilla display good success rates. However, clinicians should be discouraged from using miniscrews of length ≤ 8 mm and MIT values < 10 Ncm, even with longer miniscrews.

CLINICAL RELEVANCE

Information about factors related to failure rate of miniscrews placed at posterior maxillary interradicular sites is given.

3-D Evaluation of temporary skeletal anchorage sites in the maxilla

Background

The selection of temporary anchorage device (TAD) site can be a challenging task since one should not only consider the 2-D distances between roots, but also the entire 3-D space. Thus, the aim of this study was to evaluate the posterior maxillary region areas available for the insertion of temporary anchorage devices in reconstructed images from cone beam computed tomography (CBCT).

Material and Methods

Sample consisted of 72 patients with indication for orthodontic treatment, grouped into three distinct age groups: 11 to 14 years (age group 1), 15 to 19 years (age group 2) and aged 20 years or older (age group 3), which were further subdivided as to the type of malocclusion (Angle Class I, II and III). Orthopantomographic reconstructions and cross sections were obtained with the Dolphin Imaging software. The distance between the roots of maxillary teeth (canines, premolars and first molars) was determined at 5 mm of the cementoenamel junction, as well as the depth of bone availability at different insertion angles (90°, 75°, 60°, 45°). The influence of different angulations, age, and malocclusion on bone availability was evaluated by ANOVA, followed by the Bonferroni post-test. For the evaluation of the interaction of these factors, 2-way ANOVA was used.

Results

Bone availability was found to be poor between roots in the molar region. There was a reduction in bone availability with increasing age. With regard to angulations, greater bone availability was found in depth for 45° angulation in the canine and first premolar regions and for angulation of 75° or 90° in the molar region. However, there was no difference between bone availability in the region of the second premolars.

Conclusions

According to applied methodology it can be concluded that the region between canines and premolars accepts better vertical angular variations for TADs insertion.

Key words:Cone-Beam Computed Tomography, Orthodontic Anchorage Procedures.

Survival estimates and risk factors for failure of palatal and buccal mini-implants

OBJECTIVES

The primary objective was to compare the success and survival rates of palatal and buccal mini-implants for different locations and treatment requirements. The secondary objective was to evaluate risk factors influencing the survival of mini-implants.

MATERIALS AND METHODS

In this retrospective cohort, records of 127 orthodontic patients with 257 mini-implants were included after imposing inclusion/exclusion criteria. Along with the implant failure data, factors such as age, sex, transverse location, anteroposterior location, and purpose of mini-implants were recorded. Kaplan-Meier survival analysis was used to draw the curves and a Nathan Mantel-David Cox test to compare variables.

RESULTS

The failure rate of palatal mini-implants was 8.5%, whereas the failure rate for buccal shelf mini-implants was 68.7% (P < .0001). A significant difference was that the survival rates of palatal mini-implants were dependent on the purpose of the mini-implants and, for the buccal mini-implants, they were dependent on the skeletal malocclusion and location type of mini-implants (P < .05).

CONCLUSIONS

The overall survival rate of palatal mini-implants was high, at 91.5%. Of the buccal mini-implants, inter-radicular mini-implants had the highest survival rate for 12 (75.5%) and 24 (71.9%) months, while buccal shelf mini-implants had the lowest success and survival rates for 12 (31.3%) and 24 (20.8%) months. Class III malocclusion had the lowest survival rate for the buccal mini-implants (65.3% and 54.2%) for 12 and 24 months.

Stability and success rate of dual-thread miniscrews

OBJECTIVES

To date, the clinical stability of dual-thread orthodontic miniscrews has not been studied. This study aimed to compare the primary stability and long-term clinical success rate of dual-thread and cylindrical orthodontic miniscrews and to examine the association between various clinical factors and the success rate of miniscrews.

MATERIALS AND METHODS

A total of 145 cylindrical and 135 dual-thread miniscrews were inserted in the maxillary and mandibular buccal alveolar areas of 142 patients. The torque and Periotest (Siemens, Bensheim, Germany) values were recorded during insertion and removal. The effect of clinical variables such as sex, age, screw design, jaw, side of placement, root proximity, and site of placement on the success rate was examined using logistic regression analysis.

RESULTS

There was no statistically significant difference (P = .595) in the overall clinical success rate between the two designs, with an overall success rate of 82.1% and 84.4% for the cylindrical and dual-thread miniscrews, respectively. Age and screw-root proximity were significantly associated with failure (P < .05).

CONCLUSIONS

The dual-thread miniscrews did not show superior long-term stability and clinical success rate as compared with the cylindrical miniscrews. The results of this study suggest that patient age and screw-root proximity influence the clinical success rate of miniscrews.

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

The orthodontic miniscrew is driven into bone in a clockwise direction. Counter-clockwise rotational force applied to the implanted miniscrew can degrade the stability. The purpose of this three-dimensional finite element study was to figure out the effect of shifting the miniscrew head hole position from the long axis. Two miniscrew models were developed, one with the head hole at the long axis and the other with an eccentric hole position. One degree of counter-clockwise rotation was applied to both groups, and the maximum Von-Mises stress and moment was measured under various wire insertion angles from −60° to +60°. All Von-Mises stress and moments increased with an increase in rotational angle or wire insertion angle. The increasing slope of moment in the eccentric hole group was significantly higher than that in the centric hole group. Although the maximum Von-Mises stress was higher in the eccentric hole group, the distribution of stress was not very different from the centric hole group. As the positive wire insertion angles generated a higher moment under a counter-clockwise rotational force, it is recommended to place the head hole considering the implanting direction of the miniscrew. Clinically, multidirectional and higher forces can be applied to the miniscrew with an eccentric head hole position.

Can maxilla and mandible bone quality explain differences in orthodontic mini-implant failures?

Purpose: This study aimed to compare the risk of orthodontic mini-implant (OMI) failure between maxilla and mandible. A critical analysis of finite-element studies was used to explain the contradiction of the greatest clinical success for OMIs placed in the maxilla, despite the higher quality bone of mandible. Materials and Methods: Four tridimensional FE models were built, simulating an OMI inserted in a low-dense maxilla, control maxilla, control mandible, and high-dense mandible. A horizontal force was applied to simulate an anterior retraction of 2 N (clinical scenario) and 10 N (overloading condition). The intra-bone OMI displacement and the major principal bone strains were used to evaluate the risk of failure due to insufficient primary stability or peri-implant bone resorption. Results: The OMI displacement was far below the 50–100 µm threshold, suggesting that the primary stability would be sufficient in all models. However, the maxilla was more prone to lose its stability due to overload conditions, especially in the low-dense condition, in which major principal bone strains surpassed the pathologic bone resorption threshold of 3000 µstrain. Conclusions: The differences in orthodontic mini-implant failures cannot be explained by maxilla and mandible bone quality in finite-element analysis that does not incorporate the residual stress due to OMI insertion.

Cortical bone thickness and bone density effects on miniscrew success rates: A systematic review and meta-analysis

OBJECTIVE

To systematically review the effects of cortical bone thickness (CBT) and bone mass density (BMD) on miniscrew success rates.

METHODS

MEDLINE, the Cochrane Library and Scopus were searched up to June 2020. Of a total of 5734 articles, seven studies were finally selected for the review.

RESULTS

The overall mean success rate weighted by the number of miniscrews was 87.21% (89.87% in the maxilla and 79.24% in the mandible). There was a significantly higher success rate for miniscrews placed in the maxilla compared with those in the mandible (P < .05). CBT showed small positive effect on the success rate of the miniscrews although it failed to reach a statistical significance. The cortical BMD had a minimal effect on the success of the miniscrews. The cancellous BMD demonstrated a very strong effect on the success of the miniscrews in the maxilla, whereas it showed a moderately negative effect in the mandible.

LIMITATIONS

Because of the small number and clinical heterogeneity of the included studies, the results should be interpreted with caution. Further randomized clinical studies with a large sample size are recommended.

A Custom-Made Orthodontic Mini-Implant-Effect of Insertion Angle and Cortical Bone Thickness on Stress Distribution with a Complex In Vitro and In Vivo Biosafety Profile

BACKGROUND

Orthodontic mini-implant failure is a debatable subject in clinical practice. However, the most important parameter to evaluate the success rate of mini-implant is the primary stability, which is mainly influenced by cortical bone thickness (CBT) and insertion angle.

MATERIALS AND METHODS

Three-dimensional finite element models of the maxilla were created and a custom-made, self-drilling, tapered mini-implant was designed. For the pull-out test, 12 simulations were performed, sequentially increasing the thickness of the cortical bone (1, 1.5 and 2 mm) and the insertion angle (30°, 60°, 90°, 120°). For the force analysis, 24 simulations were performed using an experimental orthodontic traction force of 2 N both in the horizontal and vertical axis.

RESULTS

Insertion angle and CBT have significant impact on force reaction values (p < 0.05). Cortical bone stress had the lowest value when the mini-implant had a 30° insertion angle and the highest value when the implant had a 120° insertion angle, while the CBT was 1 mm. Cortical bone stress had the lowest value with an insertion angle of 90° and the highest value when the implant was inserted at an angle of 30°, while the CBT was 2 mm independent of the force direction. Regarding the biosafety profile of the mini-implant alloy, the present results reveal that the custom-made mini-implant presents good biocompatibility.

CONCLUSIONS

When the CBT is reduced, we recommend inclined insertion while, when the CBT is appropriate, perpendicular insertion is advised.

Orthodontic temporary anchorage devices: A qualitative evaluation of Internet information available to the general public

INTRODUCTION

The evaluation of online information regarding orthodontic temporary anchorage devices (TADs) is lacking despite the increase in their use by orthodontists. This cross-sectional study aimed to investigate the quality of information regarding TADs available on the Internet to the general public.

METHODS

Two search terms ("orthodontic temporary anchorage device" and "orthodontic miniscrew") were entered separately into a total of 5 search engines. The DISCERN instrument, Journal of the American Medical Association (JAMA) benchmarks, and Health on the Net Foundation Code of Conduct were used to evaluate the quality of information contained within Web sites that satisfied the inclusion and/or exclusion criteria. Web site readability was assessed via the Simple Measure of Gobbledygook and Flesch Reading Ease Score tools. Descriptive statistical analyses and Cohen's kappa intrarater reliability tests were performed.

RESULTS

Thirty-one Web sites were evaluated. Most were authored by orthodontists (77.4%) and originated from the U.S. (38.7%). The mean (standard deviation [SD]) DISCERN score was 41.87 (8.45) out of 80, with a range of 27-57. Intrarater reliability testing for DISCERN scores was excellent (0.84). Four Web sites achieved all 4 JAMA benchmarks, and 2 achieved none. Referencing of content sources throughout the Web sites scored least via DISCERN (mean 1.49 out of 5 per Web site [SD, 0.77]) and JAMA (19.35% of Web sites). One Web site contained the Health on the Net Foundation Code of Conduct seal. The mean (SD) Simple Measure of Gobbledygook score was 8.75 (1.25), with a range of 6.5-11.3. The mean (SD) Flesch Reading Ease Score was 59.81 (7.17), with a range of 47.6-73.8.

CONCLUSIONS

The quality of information related to TADs on the Internet is moderate. The usefulness of the information may be further reduced because it was beyond the readability of the average member of the general public. Web site authors should consider the use of additional expertise, quality of information tools, and readability formulas to ensure high-quality and easily readable content.

Optimal sites for mini-implant insertion in the lingual or palatal alveolar cortical bone as assessed by cone beam computed tomography in South Indian population

OBJECTIVES

To determine the optimal sites of mini-implant placement in the palatal alveolar cortical bone by using cone beam computed tomography (CBCT).

SUBJECTS AND METHODS

Cone beam computed tomography records of 60 patients were divided into two groups of equal sizes, based on age and sex. The images were analysed using Planmeca Romexis Software (Version 4.1.2). The measurements were made in axial sections of the maxilla and mandible, at 2, 4 and 6 mm from the CEJ. The optimal sites were defined in terms of (a) Palatal or lingual alveolar cortical bone thickness and (b) Mesiodistal palatal or lingual inter-radicular width.

RESULTS

The optimal site for mini-implant insertion, anteriorly, was the canine-lateral incisor embrasure in both the jaws. Posteriorly, the inter-molar embrasure in the mandible and the molar-premolar embrasure in the maxilla were optimal sites. Females demonstrated significantly lesser bone widths in all areas of the maxilla (P < .05) but greater bone thickness in the mandibular regions, as compared to males. The adolescent age group demonstrated a significantly lesser bone thickness but greater mesiodistal widths than the adult population in both the jaws (P < .05).

CONCLUSION

The optimal sites for mini-implant insertion were the anterior canine-lateral incisor and posterior buccal inter-radicular embrasures, in both the jaws. Significant differences existed between age and gender groups, which need to be kept in mind while choosing the locations for placing mini-implants.

Influence of Orthodontic Anchor Screw Anchorage Method on the Stability of Artificial Bone: An In Vitro Study

This study aims to compare the torque values for various lengths of the titanium-based orthodontic anchor screw (OAS), different anchorage methods and varying artificial bone densities after predrilling. Furthermore, the effects of these parameters on bone stability are evaluated. A total of 144 OASs were prepared with a diameter of 1.6 mm and heights of 6, 8 and 10 mm. Artificial bones were selected according to their density, corresponding to Grades 50, 40 and 30. Torque values for the automatic device and manual anchorage methods exhibited a statistically significant difference for the same-sized OAS, according to the bone density of the artificial bones (p < 0.05). However, when insertion torque was at the maximum rotations, there was no significant difference in the torque values for the Grade 30 artificial bone (p > 0.05). When the torque values of both anchorage methods were statistically compared with the mean difference for each group, the results of the manual anchorage method were significantly higher than those of the automatic device anchorage method (p < 0.05). A statistically significant difference was observed in the bone stability resulting from different OAS anchorage methods and artificial bone lengths. These findings suggest that the automatic anchorage method should be used when fixing the OAS.

[Progress on clinical application of orthodontic-implant combined therapy]

For complex implant cases, simple implantation could not achieve the desired therapeutic effect, and a multidisciplinary approach has become a general trend. Orthodontic treatment before implantation creates favorable conditions for subsequent implantation by increasing restoring three-dimensional space, improving occlusion of patients. It also stimulates the increase of autologous soft and hard tissue while biological potential of periodontal ligament is fully developed. The choice of operation time is vital to keep the level of soft and hard tissue at the implantation site, which improves the curative effect of implantation in terms of function and aesthetics. In this article, the orthodontic-implant combined therapy is briefly reviewed focusing on the three-dimensional space optimization, implant site enhancement by orthodontic extrusion and delayed orthodontic space opening.

An Umbrella Review of the Effectiveness of Temporary Anchorage Devices and the Factors That Contribute to Their Success or Failure

OBJECTIVES

New methodological approaches, such as the umbrella review, constitute an important pathway for synthesizing the scientific evidence provided from studies with a high level of evidence. This study aims to summarize the results on the effectiveness of temporary anchorage devices (TADs) and the factors that contribute to their success or failure during orthodontic treatment in patients of different age groups and to identify the gaps in knowledge based on analysis of the scientific literature.

METHODS

An umbrella review of systematic reviews and meta-analyses was performed. A quality evaluation and a descriptive analysis of the included studies were conducted. The study protocol was registered at the International Prospective Register of Systematic Reviews (PROSPERO: CRD42018094463).

RESULTS

Seventeen systematic reviews and meta-analyses were considered (10 descriptive and 7 with meta-analysis; 12 of high quality and 5 of moderate quality). Variability was observed in the type of intervention and the type of system (TADs). Most of the studies reported high success rates (≥90%), and just one systematic review indicated a low rate of success (≤56%) for the mini-screws. All the studies discussed several factors related to the success of the TADs. These factors were classified as device-related factors, patient-related factors, procedure-related factors, and orthodontic treatment-related factors. Conceptual and methodological gaps were observed when considering the data analysis, the terminology used, and the orthodontic protocols.

CONCLUSIONS

The results should be analysed cautiously because of several research gaps related to the methodological quality and the high heterogeneity of the original studies and because of the necessity to add several clinical and sociodemographic variables to enrich the data analysis.

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.

Temporary Skeletal Anchorage Techniques

As orthodontic treatment has advanced in complexity and in frequency, more recent techniques, using temporary skeletal anchorage, were developed to help correct more severe occlusal and dentofacial discrepancies that were treated with orthognathic surgery alone previously. These techniques have allowed the orthodontist to move teeth against a rigid fixation, allowing for more focused movements of teeth and for orthopedic growth modification. These types of treatments using rigid fixation have allowed for greater interaction between the orthodontist and the oral and maxillofacial surgeon, and have vastly enhanced the treatment planning for the orthodontist in today's society.

Systematic reviews in orthodontics: Impact of the PRISMA for Abstracts checklist on completeness of reporting

INTRODUCTION

This study evaluated and compared the completeness of reporting of abstracts of orthodontics systematic reviews before and after the publication of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for Abstracts Checklist (PRISMA-A).

METHODS

Abstracts of systematic reviews and meta-analyses in orthodontics published in PubMed, Latin American and Caribbean Health Sciences Literature, and the Cochrane Database of Systematic Reviews databases before March 23, 2018, that met the predefined inclusion and exclusion criteria, were evaluated using the 12 items of PRISMA-A, scoring each item from 0 to 2. Abstracts were classified into 2 groups: before and after publication of the PRISMA-A checklist. Three calibrated evaluators (intraclass correlation coefficient and kappa > 0.8) assessed the scores for compliance with the checklist. The number of authors, country of affiliation of the first author, performance of meta-analysis, and topic of the article were recorded. A regression analysis was performed to assess the associations between abstract characteristics and the PRISMA-A scores.

RESULTS

Of 1034 abstracts evaluated, 389 were included in the analysis. The mean PRISMA-A score was 53.39 (95% CI, 51.83-54.96). The overall score for studies published after the publication of the checklist was significantly higher than for studies published before (P ≤ 0.0001). The components returning significantly higher scores after publication of PRISMA-A were title (P = 0.024), information from databases (P = 0.026), risk of bias (P ≤ 0.0001), included studies (P ≤ 0.0001), synthesis of results (P ≤ 0.0001), interpretation of results (P = 0.035), financing and conflict of interest (P ≤ 0.0001), and registration (P ≤ 0.0001). These results showed the positive effect of PRISMA-A had on the quality of reporting of orthodontics systematic reviews. Nevertheless, the poor adherence revealed that there is still need for improvement in the quality of abstract reporting.

CONCLUSIONS

The quality of reporting of abstracts of orthodontic systematic reviews and meta-analyses increased after the introduction of PRISMA-A.

Evaluation of the long-term stability of micro-screws under different loading protocols: a systematic review

The aim of this systematic review was to investigate the association between the different factors of loading protocols and the long-term stability of micro-screws from biomechanical and histological viewpoints. Searches were performed on PubMed, Embase, Cochrane Library, Wanfang and CNKI databases for animal experiments comparing loading protocols and the long-term stability of micro-screws. Among 1011 detected papers, 16 studies met the eligibility criteria and were selected for analysis. Most studies showed medium methodological quality for evaluation of micro-screws' long-term stability. Five studies reported that loading would not destroy the long-term stability of micro-screws. Three studies indicated that low-intensity immediate loading or a 3-week minimal healing time was acceptable. Two studies reported that the loading magnitude was a controversial issue with regard to the micro-screws' long-term stability. Two studies suggested that counterclockwise loading could decrease the long-term stability of micro-screws. In conclusion, immediate loading below 100g force, healing time greater than 3 weeks, regular loading below 200g force and a clockwise direction of force supported the long-term stability of micro-screws. Further studies relating to the combination of varying loading conditions will be needed.

Effect of photobiomodulation on the stability and displacement of orthodontic mini-implants submitted to immediate and delayed loading: a clinical study

The aim of this study was to evaluate the effect of photobiomodulation (PBM) on the stability and displacement of orthodontic mini-implants (MIs) submitted to loading. Forty-eight and 35 mini-implants (1.5 × 8 × 1 mm) were assessed for stability and displacement, respectively (19 patients). MIs were allocated according to the intervention in 1-PBM + immediate loading (IL), 2-PBM + delayed loading (DL) (four weeks after implantation), 3-IL only, and 4-DL only. PBM (Therapy XT, DCM) was implemented using a red emission (660 nm, 4 J/cm², 0.1 W, 20 s) immediately after implantation (day 0) and infrared emissions (808 nm; 8 J/cm², 0.1 W, 40 s) in the following appointments every 48-72 h during two weeks (days 2, 4, 7, 9, 11, and 14). Loading of 150 gF was applied during three months for all MIs. The stability was assessed by resonance frequency analysis (Osstell ISQ), and images from Cone beam computed tomography were evaluated to determine the amount of the displacement of the MI's head. MIs from the PBM groups presented lower loss of stability (P = 0.0372). When the analysis considered the loading protocol as an additional variable, group two showed the lowest loss of stability, being significantly different from groups that did not receive PBM (P = 0.0161). There was no difference between groups two and four during the period without loading (P > 0.05). DL groups presented lower loss when the effective period of loading was assessed, independently of the application of PBM (P < 0.0001). All groups showed displacement of the MIs head without significant differences (P > 0.05). DL potentiated the effect of PBM, decreasing the loss of stability.

Distance to alveolar crestal bone: a critical factor in the success of orthodontic mini-implants

Background

To evaluate the success rate of orthodontic mini-implant (MI) in relation to implant characteristics, mainly implant distance to alveolar crestal bone (AC) and root proximity (RP) to adjacent teeth.

Methods

Two hundred sixty MIs (209 in maxilla, 51 in mandible) were categorized into success (n = 229) and failure (n = 31) groups. Distances from MI to the most adjacent tooth (DT) and to AC level (DC) were measured on periapical radiographs taken with the orthoradial projection technique. Appropriate statistical tests (chi-square, t test, logistic regression) were applied.

Results

DC measurements were statistically significantly greater in the success group (7.46 ± 1.7 mm) compared to 3.43 ± 0.81 mm in the failure group. Root proximity was not associated with miniscrew failure. Patient age, mini-implant site, and DC were significant predictors of mini-implant failure (p < 0.001), which decreased significantly with increasing age (Coef = − 0.345; p = 0.013) and when the mini-implant was placed between premolars (p = 0.028) or between premolar and first molar (p = 0.045). The probability of failure also decreased with increasing DC distance (Coef = − 3.595; p < 0.001).

Conclusion

The distance to alveolar crest was strongly associated with long-term stability. More apical placement of the MI from the crest would be compatible with a denser and thicker bucco-lingual/palatal bone level.

Treatment of a severe Class II Division 1 malocclusion combined with surgical miniscrew anchorage

This article reports the camouflage treatment of a female patient, aged 15 years 2 months, who had a Class II Division 1 malocclusion with severe anterior protrusion and deep incisor overbite. The camouflage treatment plan included bilateral extraction of the maxillary first premolars combined with the use of temporary anchorage devices (TADs) and tension coil springs to retract canines into the extraction spaces and then the 4 incisors. The treatment included use of a mandibular fixed labial arch with minimal use of Class II elastics to correct mild mandibular spacing and level the curve of Spee. Ideal overjet and overbite relationships were established, and the final result was well balanced and esthetically pleasing. The molars were finished in a Class II relationship. Total treatment time was 2 years 6 months. Cephalometric superimpositions revealed that mandibular molars were not disturbed by the limited use of Class II elastics. Surgical miniscrews in canine and incisor retraction in Class II Division 1 malocclusion are an alternate type of temporary anchorage that reduce or remove reliance on conventional intermaxillary anchorage.

Surface Characterization and Copper Release of a-C:H:Cu Coatings for Medical Applications

This paper focuses on the surface properties of a-C:H:Cu composite coatings for medical devices and how the release of Cu2+ ions from such coatings can be controlled. The released Cu ions have the potential to act as a bactericidal agent and inhibit bacterial colonization. A PVD–PECVD hybrid process was used to deposit a-C:H:Cu composite coatings onto Ti6Al4V substrates. We examine the layer surface properties using atomic force microscopy and static contact angle measurements. An increasing surface roughness and increasing contact angle of Ringer’s solution was measured with increasing copper mole fraction (XCu) in the coatings. The contact angle decreased when a supplementary bias voltage of −50 V was used during the a-C:H:Cu deposition. These findings are in line with earlier published results regarding these types of coatings. The release of Cu2+ ions from a-C:H:Cu coatings in Ringer’s solution was measured by anodic stripping voltammetry. Different layer structures were examined to control the time-resolved Cu release. It was found that the Cu release depends on the overall XCu in the a-C:H:Cu coatings and that an additional a-C:H barrier layer on top of the a-C:H:Cu layer effectively delays the release of Cu ions.

Perception of mini-screw anchorage devices by patients

OBJECTIVE

To evaluate how mini-screw anchorage are perceived by patients as well as their degree of satisfaction regarding their orthodontic treatment.

MATERIAL AND METHODS

A questionnaire was handed out to the study population which comprising 137 patients all undergoing orthodontic treatment, without exclusion criteria.

RESULTS

Out of the total number of 230 questionnaires distributed to patients, only 137 (60%) questionnaires were returned (sample 1) bearing in mind that 29 patients (21.2%) were fitted with a mini-screw (sample 2). In sample 2, 86.20% of patients showed no sign of mini-screw instability during treatment. The majority of patients (62.10%) reported no pain when the mini-screws were inserted (62.1%) and among the 37.9% who did feel pain, 60% were boys and 26.3% were girls, without significant difference, P<0.11. Post-op pain decreased steadily between day 1 and day 7 regardless of the orthodontic technique used (P>0.5). When pain was felt during the 7-day period, it was significantly greater for initial tooth alignment than for micro-implant surgery (P<0.05). Most patients declared themselves satisfied with the orthodontic treatment using anchorage devices, with a 72.4% satisfaction rate.

CONCLUSION

Overall, the use of mini-screw anchorage devices during orthodontic treatment is well accepted by patients. The stability rate is high with predictable results. Post-op pain is significantly lower than orthodontic alignment pain.

A novel technique for measurement of orthodontic mini-implant stability using the Osstell ISQ device

OBJECTIVES

To develop and validate a method for application of the Osstell ISQ device in the assessment of mini-implant stability.

MATERIALS AND METHODS

An adaptor was developed for attachment of Osstell's SmartPeg onto a variety of orthodontic mini-implants. For validation of the adaptor, Benefit mini-implants were inserted into bone blocks that mimicked different stability conditions. The Osstell device was used to assess mini-implant stability with the adaptor (test measurement) and conventional SmartPeg attachment (gold-standard measurement). Implant stability quotient (ISQ) values were assessed for agreement, repeatability, and reproducibility.

RESULTS

Strong positive correlations were found between ISQ values obtained using the novel adaptor and the conventional attachment. Repeatability and reproducibility of ISQ values with the adaptor were similar to those obtained with the conventional attachment.

CONCLUSIONS

A method was developed and validated to assess the stability of orthodontic mini-implants using the Osstell system. The novel mini-implant adaptor provided repeatable and reproducible measurements of mini-implant stability, which agreed with those obtained using a conventional SmartPeg attachment. This adaptor permits noninvasive stability assessment of various designs of mini-implants, most of which are incompatible with the conventional SmartPeg attachment.

A comparative histomorphological and micro computed tomography study of the primary stability and the osseointegration of The Sydney Mini Screw; a qualitative pilot animal study in New Zealand rabbits

Objective

The aim of this study was to assess the potential of improving orthodontic miniscrews’ (MSs) primary stability in vivo by evaluating the dispersion capacity of an injectable bone graft substitute (iBGS) through a newly designed hollow MS [The Sydney Mini Screw (SMS)] and its integration with the cortical and trabecular bone by using the femur and tibia in a New Zealand rabbit animal model.

Methods

In total, 24 MSs were randomly placed in each proximal tibia and femur of 6 New Zealand rabbits with an open surgery process. Aarhus MSs were used as controls and the effect of injection of iBGS was studied by implanting SMSs with and without iBGS injection. The dispersion of iBGS and the integration of the SMS were studied by using micro Computed Tomography (μCT) and histochemical analysis at two time points, 0 day and 8 weeks post-implantation.

Results

iBGS was successfully injected through the SMS and hardened in situ. After 8 weeks, μCT results revealed that the iBGS particles were resorbed and bone tissue was formed around the SMS and within its lateral exit holes.

Conclusions

This pilot animal study showed the high potential of the combined use of iBGS and SMS as a newly developed technique to promote the primary stability of MSs.