Immediate versus delayed loading: comparison of primary stability loss after miniscrew placement in orthodontic patients-a single-centre blinded randomized clinical trial

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

AIM

There is limited research on the clinical performance of double-thread orthodontic miniscrews. This study aimed to compare the stability of double-thread and single-thread orthodontic miniscrews and identify the potential associations between patient-related and location-related factors with miniscrew stability.

METHODS

This retrospective cohort study involved 90 orthodontic miniscrews (45 single-thread, 45 double-thread) with identical dimensions (8 mm length, 1.6 mm diameter). The screws were inserted in various locations within the upper jaw of 83 patients (54 females, 29 males; mean age = 15.1 ± 2.4 years). Failure was defined as excessive mobility or loss of miniscrew after placement. The data recorded were patient age, gender, insertion site, side of insertion (buccal or lingual), duration of force application, and failure occurrence.

RESULTS

The overall success rate within the sample was 92.2%. Double-thread miniscrews exhibited a significantly higher success rate than single-thread miniscrews (P = 0.049), with 97.8% and 86.7% success rates, respectively. Gender, age, insertion location, and side of insertion did not show significant associations with failure (P > 0.05). Log-rank analysis revealed a significant difference between the two groups (P = 0.046), indicating a higher probability of survival for the double-thread design.

CONCLUSIONS

The overall success rate of orthodontic miniscrews was high in the present sample. Double-thread miniscrews placed in various locations within the maxillary arch demonstrated superior stability and survival rates compared to their single-thread counterparts. Therefore, double-thread miniscrews may be preferred when bone quality is inadequate, such as in young patients.

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.

Aligner hybrid orthodontic approach to treat severe transverse divergence in an adolescent girl: A case report

OBJECTIVE

To resolve a complex Class II case with unilateral crossbite through an aesthetic approach, namely a hybrid orthodontic treatment combining aligners with miniscrews and auxiliaries.

MATERIALS AND METHODS

A 14-year-old hypodivergent female patient with dental Class II and posterior crossbite presented for orthodontic treatment. The patient refused conventional fixed multibracket treatment and was therefore prescribed aligners used in association with miniscrews and sectional lingual appliances. Pre- and post-treatment records and 2-year follow-up records are presented.

RESULTS

Treatment objectives, namely ideal occlusion and improved profile, were achieved in 12 months. Post-treatment panoramic radiography showed good root parallelism, and no sign of either crestal bone height reduction or apical root resorption. The patient was satisfied with the functional and aesthetic outcomes, which were stable at 2 years.

CONCLUSION

This case report illustrates that a hybrid aligner approach may be used to treat posterior crossbite and class II malocclusion with reduced treatment times, optimal oral hygiene and excellent aesthetics.

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.

Long-term evaluation of factors affecting removal torque of microimplants

Background

The current study aimed to evaluate factors affecting the long-term stability of microimplants using removal torque and the correlation between removal torque and clinical variables.

Materials and methods

This research evaluated 703 microimplants placed in 354 patients (mean age: 30.4 ± 12.1 years). The removal torque was evaluated according to various clinical variables including sex, age, placement site, microimplant size, and placement method (self-drilling versus pre-drilling). Pearson correlation and stepwise multiple linear regression analyses were performed to investigate different variables and their association with removal torque.

Results

The mean removal torque was significantly higher in the mandible (4.46 N cm) than in the maxilla (3.73 N cm). The values in the posterior teeth/retromolar areas were significantly higher than those in the anterior teeth area. There were no significant difference in terms of sex. Teenagers had a lower removal torque than older adults in the mandible, but not in the maxilla. Microimplants with a greater length and diameter, except for those with a greater diameter in the maxilla, was associated with a higher removal torque. Regardless of placement torque, the removal torque convergently reached approximately 4 N cm in both placement methods. The removal torque was significantly correlated with screw length in the self-drilling group and with diameter in the pre-drilling group.

Conclusions

Removal torque was related with placement site, age, placement method, and length and diameter of microimplants.

A Simplified Digital Approach to the Treatment of a Postpuberty Patient with a Class III Malocclusion and Bilateral Crossbite

Monolateral and bilateral crossbites are amongst the most frequent forms of malocclusion in the world population. The lack of early correction of this type of malocclusion leads to the partial or total ossification of the sutures which then require surgical treatment in adult patients. In recent years, devices on minipalatal screws have noticeably increased the time window in which it is possible to correct these types of alterations. In this case report, we show how it is possible to correct a third-class skeletal malocclusion associated with a posterior bilateral crossbite in a young woman using a rapid expander on miniscrews and fixed orthodontic device to finalise the process. The procedure for the insertion of the palatal screws was aided by the use of a digitally printed surgical guide, and the appliance was applied in the same sitting thanks to the use of a digital flow software and a systematic easy driver. The CBCT scans show how the orthopaedic expansion of the upper maxilla was obtained without any important alterations that damaged the permanent teeth. This case report wishes to demonstrate how easy and predictable it can be to resolve cases of this type with optimal aesthetic and functional results even when body growth has ended.

Rapid Palatal Expansion Should Not Be Trivialized: Two Case Reports of Unexpected Complications

Rapid maxillary expansion is one of the most common orthodontic procedures performed in the pediatric population, easy to accomplish and compliance free, therefore really effective. Nevertheless, a careful diagnosis and frequent clinical follow-up appointments are necessary during the first weeks of active treatment. The purpose of this article was to report two cases of unexpected complications during orthopaedic maxillary expansion, involving two 7-year-old female patients, one presenting a saddle nose with suborbital hematoma and the other one an asymmetric palatal expansion. In both cases, the clinical situation progressively relapsed during the months following expansion appliance removal.

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.

Class II subdivision with skeletal transverse maxillary deficit treated by single-sitting bone-borne appliance

This case report describes orthodontic treatment including both skeletal maxillary expansion and unilateral distalization by means of a single bone-borne appliance followed by clear aligner therapy in a young adult patient. A surgical guide was digitally designed and three-dimensionally printed to facilitate the placement of four miniscrews in the palatal vault. The miniscrews were fitted and the bone-borne appliance was delivered in a single clinical appointment. The postexpansion photographic records and models demonstrate the opening of the palatal median suture, the pure skeletal expansion, and the resolution of the left crossbite after 40 activations. Specifically, left molar Class I was obtained in about 5 months without any loss of anterior anchorage, and the subsequent aligner phase achieved all of the objectives established in the treatment plan. This case report shows clearly how careful digital planning of miniscrew insertion and the delivery of a pure bone-borne appliance in a single sitting enabled good clinical outcomes to be achieved in an acceptable timeframe, without side effects, even in a young adult patient.

Three dimensional movement analysis of maxillary impacted canine using TADs: a pilot study

BACKGROUND

The aim of the present study was to compare two different anchorage systems efficiency to disinclude impacted maxillary canines using as evaluation tool superimposed Cone Beam Computed Tomography (CBCTs).

METHODS

The study has been conducted with two parallel groups with an allocation ratio of 1:1. Group test received treatment using as anchorage a miniscrew, control group was treated using an anchorage unit a trans palatal arch (TPA). Both groups received a calibrated traction force of 50 g. CBCT before treatment and 3 months after traction were superimposed and canine tip and root movement were evaluated in mm/month ratio.

RESULTS

No differences were observed between groups for apex displacement, tip displacement and observation timespan. Twenty-two patients (12 female, 10 male, mean age:13.4 years) undergoing orthodontic treatment for impacted maxillary canines were recruited for this study. No differences were observed between groups for apex displacement, tip displacement and observation timespan.

CONCLUSIONS

The present pilot study provided no evidence that indirect anchorage on miniscrews could make canine disimpaction faster than anchorage on a TPA. An apex root movement of 0.4-0.8 mm per month was found, while average canine tip movement ranged between 1.08 mm and 1.96 mm per month. No miniscrews failures were observed.

TRIAL REGISTRATION

The study reports the preliminary results of the randomized clinical trial registered at www.register.clinicaltrials.gov (registration number: NCT01717417 ).

Maximum insertion torque loss after miniscrew placement in orthodontic patients: A randomized controlled trial

OBJECTIVES

To compare torque recordings of immediately loaded orthodontic miniscrews between insertion time and different post-placement timepoints (2 weeks, 4 weeks and removal time, respectively).

SETTING AND SAMPLE POPULATION

Parallel trial with an allocation ratio of 1:1. Eligibility criteria were needs of fixed orthodontic treatment, no systemic disease and absence of using drugs altering bone metabolism.

MATERIAL AND METHODS

Patients received miniscrews, 2.0 mm diameter and 10 mm length. All miniscrews underwent inter-radicular placement, and they were placed in the maxilla or in the mandible, palatally or buccally. No pre-drilling was performed. Miniscrews were loaded immediately after the insertion and were used for distalization, intrusion, extrusion, mesialization or indirect anchorage. Patients were randomly divided into three groups. For each patient, Maximum Insertion Torque (MIT) was evaluated at baseline. MIT was measured again after 2 weeks and after 4 weeks by tightening the screw a quarter of turn in Groups 1 and 2, respectively. At the end of the treatment, maximal removal torque was evaluated in Group 3. Torque variation with respect to insertion time was considered as the primary outcome. Baseline and longitudinal differences were tested using the linear mixed-effects (LME) model.

RESULTS

Forty seven patients and 74 miniscrews were followed up. An association existed between maximum insertion torque and the observation time. A torque decrease of 26.9% and 30% after 2 weeks was observed for mandibular and maxillary miniscrews, respectively. After 1 month, torque values were similar to the baseline records. The overall success rate was 79.7%. No serious harm was observed.

CONCLUSIONS

Maximum insertion torque undergoes a loss during the first 2 weeks, and its values may depend on the insertion site and the anchorage purpose. Removal torque value is almost the same as the initial torque after 1 month.

Influence of orthodontic loading on biomarkers levels around miniscrews

OBJECTIVE

The aim of this study was to evaluate the levels of Interleukin-1α (IL-1α), Interleukin-1β (IL-1β), Interleukin-1 receptor antagonist (IL-1Ra), Interleukin-10 (IL-10), Interleukin-13 (IL-13), Vascular endothelial growth factor (VEGF), Granulocyte-colony stimulating factor (G-CSF), and Growth related oncogene (GRO) in the peri-miniscrew implant crevicular fluid (MICF) under orthodontic loading.

DESIGN

The study sample comprised 14 miniscrews immediately loaded and 17 unloaded ones. A load of 200gF was immediately applied to the miniscrews in the loaded group after the placement surgery. Peri-miniscrew implant crevicular fluid was collected at baseline, at day 7, and at day 21. The levels of the biomarkers were measured using a multiplexed bead immunoassay. Intergroup comparisons were made using Mann-Whitney test. Friedman and Dunn's multiple comparison tests were used to evaluate intragroup differences over time.

RESULTS

Although no statistical differences were observed between the groups at any time point for any of the 8 biomarkers evaluated, there was a statistically significant increase (p < 0.02) in the levels of all the biomarkers over time on both groups.

CONCLUSIONS

An immediate loading of 200gF does not alter the balance in the inflammatory response in peri-miniscrew tissues.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

On the stability efficiency of anchorage self-tapping screws: Ex vivo experiments on miniscrew implants used in orthodontics

BACKGROUND

The clinical success of orthodontic miniscrews is strictly related to primary stability, which depends on bone viscoelastic properties too. In this study, we evaluated the short time mechanical response of native bone to miniscrews, by a laboratory test based on dynamic loading.

METHODS

Thirty-six segments of porcine ribs were first scanned by cone-beam computerized tomography to obtain insertion-site cortical thickness, cortical and marrow bone density. Twelve different types of miniscrews were implanted in the bone samples to evaluate the elastic compliance of the implants in response to a point force applied at the screw head normally to the screw axis. The compliance was measured dynamically in a Dynamic Mechanical Analysis apparatus as the Fourier Response Function between the signals of displacement and force. The measurements were repeated in five days successive to the insertion of the miniscrew.

FINDINGS

The elastic compliance was positively related to observation timepoints, but it was not related neither to the screw type nor to the value of the insertion torque.

INTERPRETATION

Stability behavior is significantly related to the short time response of native bone rather than to the screw design or the insertion torque values.

A review of biomarkers in peri-miniscrew implant crevicular fluid (PMICF)

Background

The temporary anchorage devices (TADs) which include miniscrew implants (MSIs) have evolved as useful armamentarium in the management of severe malocclusions and assist in complex tooth movements. Although a multitude of factors is responsible for the primary and secondary stability of miniscrew implants, contemporary research highlights the importance of biological interface of MSI with bone and soft tissue in augmenting the success of implants.

The inflammation and remodeling associated with MSI insertion or loading are reflected through biomarkers in peri-miniscrew implant crevicular fluid (PMICF) which is analogous to the gingival crevicular fluid. Analysis of biomarkers in PMICF provides indicators of inflammation at the implant site, osteoclast differentiation and activation, bone resorption activity and bone turnover. The PMICF for assessment of these biomarkers can be collected non-invasively via paper strips, periopaper or micro capillary pipettes and analysed by enzyme-linked immunosorbent assay (ELISA) or immunoassays. The markers and mediators of inflammation have been previously studied in relation to orthodontic tooth movement include interleukins (IL-1β, IL-2, IL-6 and IL-8), growth factors and other proteins like tumour necrosis factor (TNF-α), receptor activator of nuclear factor kappa-B ligand (RANKL), chondroitin sulphate (CS) and osteoprotegerin (OPG).

Studies have indicated that successful and failed MSIs have different concentrations of biomarkers in PMICF. However, there is a lack of comprehensive information on this aspect of MSIs. Therefore, a detailed review was conducted on the subject.

Results

A literature search revealed six relevant studies: two on IL-1β; one on IL-2, IL-6 and IL-8; one on TNF-α; one on CS; and one on RANKL/OPG ratio. One study showed an increase in IL-1β levels upon MSI loading, peak in 24 hours (h), followed by a decrease in 21 days to reach baseline in 300 days. A 6.87% decrease in IL-2 levels was seen before loading and a 5.97% increase post-loading. IL-8 showed a 6.31% increase after loading and IL-6 increased by 3.08% before MSI loading and 15.06% after loading. RANKL/OPG ratio increased in loaded compared to unloaded MSIs.

Conclusions

Cytokines (mainly ILs and TNF-α) and RANKL/OPG ratio showed alteration in PMICF levels upon loading of MSIs as direct or indirect anchorage.

[Orthodontic correction of malpositioned teeth before restorative treatment: efficiency improvement using Temporary Anchorage Devices (TADs)]

INTRODUCTION

Orthodontic treatment is a fundamental tool when approaching in a multidisciplinary manner a prosthetic rehabilitation, thanks to the possibility to place in an ideal position the involved teeth and to improve or even correct any periodontal defects. Several orthodontic tricks and version have been developed to limit as much as possible orthodontic appliances extension and treatment duration. However, it is not always easy to control teeth movements and manage anchorage when only few teeth are involved. Furthermore, treatment duration can increase due to the need to apply light forces and to correct adverse dental movements that eventually could appear.

MATERIAL AND METHODS

Different clinical cases are presented.

RESULTS

These exemples illustrate how, with the addition of the TADs in clinical practice, the biomechanics of the multidisciplinary treatment can be simplified, the result becomes highly predictable and the treatment time can often be reduced.