Anchorage Reinforcement Research Articles

Moderate quality evidence that surgical anchorage more effective than conventional anchorage during orthodontic treatment.

Cochrane Oral Health Groups Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, key international orthodontic and dental journals and the World Health Organization (WHO) International Clinical Trials Registry Platform. Randomised controlled trials comparing surgical anchorage with conventional anchorage in orthodontic patients. Trials comparing two types of surgical anchorage were also included. Data extraction was performed independently and in duplicate by three review authors and the Cochrane risk of bias tool was used to assess bias. Random-effects meta-analysis was used for more than three studies when pooling of the data was clinically and statistically appropriate. Fixed-effect analysis was undertaken with two or three studies. Fifteen studies, involving 543 analysed participants, were included. Five ongoing studies were identified. Eight studies were assessed to be at high overall risk of bias, six at unclear risk and one study at low risk of bias. Ten studies (407 randomised and 390 analysed patients) compared surgical anchorage with conventional anchorage for the primary outcome. A random-effects meta-analysis of seven studies for the primary outcome found strong evidence of an effect of surgical anchorage. Compared with conventional anchorage, surgical anchorage was more effective in the reinforcement of anchorage by 1.68 mm (95% CI -2.27 mm to -1.09 mm) (moderate quality evidence). This result should be interpreted with some caution, however, as there was a substantial degree of heterogeneity for this comparison. There was no evidence of a difference in overall duration of treatment between surgical and conventional anchorage (low quality of evidence).Information on patient-reported outcomes such as pain and acceptability was limited and inconclusive. When direct comparisons were made between two types of surgical anchorage, there was a lack of evidence to suggest that any one technique was better than another. There is moderate quality evidence that reinforcement of anchorage is more effective with surgical anchorage than conventional anchorage, and that results from mini-screw implants are particularly promising. While surgical anchorage is not associated with the inherent risks and compliance issues related to extra-oral headgear, none of the included studies reported on harms of surgical or conventional anchorage.

Application and anatomical considerations of skeletal temporary anchorage devices (TADs) in contemporary orthodontics

In contemporary orthodontic treatment skeletal temporary anchorage devices (TADs) are routinely used as an anchorage reinforcement to provide improved anchorage control with reduced requirement for patient's compliance. For past few decades, various types of TADs have been explored and their clinical application has been expanded. Therefore, the purpose of this article is to present three major types of orthodontic skeletal anchorage devices and discuss their rationale, clinical procedure, insertion site, and potential complications as well as their management.

Reinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods.

The term anchorage in orthodontic treatment refers to methods of controlling unwanted tooth movement. This is provided either by anchor sites within the mouth, such as the teeth and the palate, or from outside the mouth (headgear). Recently, new methods of providing anchorage have been developed using orthodontic implants which are surgically inserted into the bone in the mouth. This is termed surgical anchorage. This is an update of a Cochrane review first published in 2007. To assess the effects of surgical anchorage techniques compared to conventional anchorage in the prevention of unwanted tooth movement in patients undergoing orthodontic treatment by evaluating the mesiodistal movement of upper first molar teeth. A secondary objective was to compare the effects of one type of surgical anchorage with another. We searched the Cochrane Oral Health Group's Trials Register (to 28 October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 9), MEDLINE via OVID (1946 to 28 October 2013) and EMBASE via OVID (1980 to 28 October 2013). We handsearched key international orthodontic and dental journals, and searched the trial database ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing and unpublished studies. Randomised controlled trials comparing surgical anchorage with conventional anchorage in orthodontic patients. Trials comparing two types of surgical anchorage were also included. At least two review authors independently and in duplicate extracted data and carried out risk of bias assessments. We contacted study authors to clarify aspects of study design and conduct, and to obtain unreported data. Fourteen new studies were added in this update resulting in a total of 15 studies reporting data from 561 randomised patients. The studies were conducted in Europe, India, China, South Korea and the USA. The age range of patients was commonly restricted to adolescents or young adults, however the participants of two studies were from a much wider age range (12 to 54 years). The distribution of males and females was similar in eight of the studies, with a predominance of female patients in seven studies.Eight studies were assessed to be at high overall risk of bias; six studies at unclear risk of bias; one study at low risk of bias.Ten studies with 407 randomised and 390 analysed patients compared surgical anchorage with conventional anchorage for the primary outcome of mesiodistal movement of upper first molars. We carried out a random-effects model meta-analysis for the seven studies that fully reported this outcome. There was strong evidence of an effect of surgical anchorage on this outcome. Compared with conventional anchorage, surgical anchorage was more effective in the reinforcement of anchorage by 1.68 mm (95% confidence interval (CI) -2.27 mm to -1.09 mm; seven studies, 308 participants analysed) with moderate quality of evidence (one study at high overall risk of bias, five studies at unclear risk of bias, one study at low risk of bias). This result should be interpreted with some caution, however, as there was a substantial degree of heterogeneity for this comparison. There was no evidence of a difference in overall duration of treatment between surgical and conventional anchorage (-0.15 years; 95% CI -0.37 years to 0.07 years; three studies, 111 analysed patients) with low quality of evidence (one study at high overall risk of bias and two studies at unclear risk of bias). Information on patient-reported outcomes such as pain and acceptability was limited and inconclusive.When direct comparisons were made between two types of surgical anchorage, there was a lack of evidence to suggest that any one technique was better than another.No included studies reported adverse effects. There is moderate quality evidence that reinforcement of anchorage is more effective with surgical anchorage than conventional anchorage, and that results from mini-screw implants are particularly promising. While surgical anchorage is not associated with the inherent risks and compliance issues related to extraoral headgear, none of the included studies reported on harms of surgical or conventional anchorage.

A novel way of correcting class II buccal segment occlusions

This paper presents five clinical cases demonstrating the use of the Upper Begg Lower Straight Wire (SWA) technique. It is a method for correcting Class II buccal segments but not involving the classic Begg technique. It frees the occlusion and tips the upper buccal segment teeth distally, and then a Nance button is used for anchorage reinforcement whilst the teeth are uprighted. Clinical Relevance: This article outlines an alternative method for correcting Class II buccal segments without the need for extractions.

Effectiveness of 3 methods of anchorage reinforcement for maximum anchorage in adolescents: A 3-arm multicenter randomized clinical trial

The objective of this 3-arm parallel randomized clinical trial was to compare the effectiveness of temporary anchorage devices (TADs), Nance button palatal arches, and headgear for anchorage supplementation in the treatment of patients with malocclusions that required maximum anchorage. This trial was conducted between August 2008 and February 2013 in 2 orthodontic departments in the United Kingdom. The study included 78 patients (ages, 12-18 years; mean age, 14.2 years) who needed maximum anchorage. Eligibility criteria included no active caries, exemplary oral hygiene, and maximum anchorage required. The primary outcome was mesial molar movement during the period in which anchorage supplementation was required. The secondary outcomes were duration of anchorage reinforcement, number of treatment visits, number of casual and failed appointments, total treatment time, dento-occlusal change, and patients' perceptions of the method of anchorage supplementation. Treatment allocation was implemented by contacting via the Internet the randomization center at the University of Nottingham, Clinical Trials Unit. The randomization was based on a computer-generated pseudo-random code with random permuted blocks of randomly varying size. A research assistant who was blinded to the group allocation recorded all data. The patients were randomly allocated to receive anchorage supplementation with TADs, a Nance button on a palatal arch, or headgear. They were all treated with maxillary and mandibular preadjusted edgewise fixed appliances with 0.022-in slot prescription brackets. They were followed until orthodontic treatment was complete. Seventy-eight patients were randomized in a 1:1:1 ratio among the 3 groups. The baseline characteristics were similar in the groups, and they were treated for an average of 27.4 months (SD, 7.1 months); 71 completed orthodontic treatment. The data were analyzed on a per-protocol basis and showed no differences in the effectiveness of anchorage supplementation between TADs, Nance button palatal arches, and headgear. Compared with headgear, the average mesial movements of the maxillary right molar were 0.62 mm (-0.32 to 1.55 mm) with the Nance and -0.58 mm (-1.53 to 0.36 mm) with TADs; the maxillary left molar was moved -0.09 mm (-1.00 to 0.83 mm) with the Nance and -0.96 mm (-1.89 to -0.04 mm) with the TADs. Peer assessment rating scores were significantly better with the TADs than in the headgear and Nance groups. The patient questionnaires showed that comfort levels on placement of the TADs and the Nance were similar. Headgear was more troublesome and less popular with the patients. There was no difference in the effectiveness between the 3 groups in terms of anchorage support. There were more problems with the headgear and Nance buttons than with the TADs. The quality of treatment was better with TADs. As a result, TADS might be the preferred method for reinforcing orthodontic anchorage in patients who need maximum anchorage. ClinicalTrials.gov Identifier: NCT00995436. The protocol was published on the above site before the trial commencement. The British Orthodontic Society Foundation funded the study and American Orthodontics provided all the TADs and associated equipment.

Stability of miniscrews with different continuous orthodontic forces as measured by cone-beam computed tomography

PurposeMiniscrew stability is a key for successful orthodontic anchorage reinforcement. Light force as 50g has been proposed to efficiently retract canine; however, for miniscrew stability, its efficiency is still questionable. This study aimed to evaluate and compare miniscrew displacements loaded with 50 and 150g to retract upper canines. Subjects and methodsTwenty four miniscrews (1.4mm diameter and 7mm length) were placed in twelve orthodontic patients (female, 22.55±4.8 years old) who required miniscrews for maximum anchorage. Cone-beam computed tomography (CBCT) was taken to assess the miniscrew displacement in three dimensions. The X, Y, Z coordination points at the miniscrew head and tail with anterior nasal spine as a reference point were recorded and analyzed the displacements during 3 months using one-sample t-test and pair t-test. ResultsMiniscrews were significantly displaced after loading 50 and 150g at 2 and 3 months compared to baseline (P<0.001). At 2 months, the displacement of the miniscrews at head and tail had no statistical significance between 50 and 150g (P>0.05). However, at 3 months, there were statistically significant displacements between 50 and 150g. This displacement was found to be greater in 150g and at head more than at tail (P<0.05). ConclusionThis study concluded that miniscrews could be significantly displaced with 50 and 150g during 3 months wherein the heavier loading force essentially caused more miniscrew mobility. Clinically, it is suggested to use proper magnitude of force to miniscrews with care in order to overcome orthodontic anchorage failure.

Study of the Anchorage Seismic Performance for Beam-Ends Strengthened by Bonded Rebars

This article firstly designed four specimens, including a contrastive specimen and three chemical anchorage reinforcement specimens which reinforcing the beam ends in different ways and then applied low-cycle reciprocating to the four specimens. This paper analyzed the anchor failure performance of the anchorage specimens by testing and data .The research concluded that the chemical anchorage can meet the component single drawing to components yield without failure. With the increasing of the loading series and the cycles improving, the parts of the anchor bars were pulled out.

Effectiveness ofen-masseretraction using midpalatal miniscrews and a modified transpalatal arch: Treatment duration and dentoskeletal changes

ObjectiveThe purpose of this study was to compare the treatment duration and dentoskeletal changes between two different anchorage systems used to treat maxillary dentoalveolar protrusion and to examine the effectiveness of en-masse retraction using two miniscrews placed in the midpalatal suture.MethodsFifty-seven patients (9 men, 48 women), who had undergone level anchorage system treatment at Aichi-Gakuin University Dental Hospital (Nagoya, Japan) were divided into two groups according to the method of maxillary posterior anchorage reinforcement: midpalatal miniscrews (25 patients, mean age 22 years) and conventional anchorage (32 patients, mean age 19 years). The en-masse retraction period, overall treatment duration, pre-treatment effective ANB angle, and change in the effective ANB angle were compared with an independent-samples t-test.ResultsCompared to the headgear group, the duration of en-masse retraction was longer by approximately 4 months in the miniscrew group (p < 0.001). However, we found no significant difference in the total treatment duration between the groups. Moreover, a greater change in the effective ANB angle was observed in patients treated with miniscrews than in those treated with the conventional method (p < 0.05).ConclusionsThe level anchorage system treatment using miniscrews placed in the midpalatal area will allow orthodontists more time to control the anterior teeth during en-masse retraction, without increasing the total treatment duration. Furthermore, it achieves better dentoskeletal control than does the conventional anchorage method, thereby improving the quality of the treatment results.

Perforación radicular asociada al uso de microtornillos en el anclaje ortodóncico: Reporte de un caso

The aim of this publication is to present one of the possible complications associated with the placement of interradicular miniscrews for the reinforcement of anchorage in orthodontics. This case report describes the surgical treatment of a maxillary first molar as a solution for the iatrogenic perforation of its mesiobuccal root after the placement of a microscrew for the reinforcement of the orthodontic anchorage in an adult patient.

Effects of retraction force and anchorage reinforcement on occlusal force: a model study

The aim of this study was to investigate the effects of retraction force and anchorage reinforcement with orthodontic mini implants on occlusal force. A strain gauge was attached to the palatal surface of the maxillary right first molar on an en masse retraction model. Occlusal forces were measured from this model, according to different retraction forces that were generated by elastic chain, under varied compressive forces (simulating masticatory forces). This retraction experiment was then performed again, after using anchorage reinforcement with an orthodontic mini implant. Occlusal force decreased as retraction force increased. The decrease showed a significant difference above 150g of retraction force (P < 0.05) and was more definite under compressive force higher than 150 N (P < 0.001). After anchorage reinforcement with the orthodontic mini implant, however, occlusal force did not significantly decrease with increasing retraction force. Significant differences in occlusal force were noted between the conditions with and without anchorage reinforcement when the applied retraction force was greater than 200g. Occlusal force tends to decrease during retraction, and this decrease can be prevented by anchorage reinforcement with orthodontic mini implants. Further investigation on the actual masticatory process in humans is required for more clear clinical implication.

Current evidence on clinical performance of miniscrew implants in orthodontic treatment

Miniscrew implants (MIs) have been widely used for anchorage reinforcement in orthodontics and have been extensively studied, especially during the last few years. However, evidence regarding their survival and clinical effectiveness is modest at the time. This article presents data from systematic reviews of prospective studies on the use of MIs. Limited but strong evidence supports the superior effectiveness of MIs compared to conventional anchorage. The average failure rate of MIs is relatively low, but the factors affecting it have not been adequately studied until recently. MI prognosis is independent of patient's gender, patient's age, and insertion side. In contrast, MIs inserted in the mandible are at a higher risk of failure than in the maxilla. However, although there are many issues based only on weak scientific evidence, some trends are already evident and are presented in this paper. Further high-quality large-scale studies are needed to clarify the association of the various factors with MI failures.

Midpalatal miniscrews and high-pull headgear for anteroposterior and vertical anchorage control: Cephalometric comparisons of treatment changes

Our aim was to evaluate which anchorage system is better suited for both anteroposterior and vertical anchorage control of maxillary posterior teeth. Fifty-one subjects requiring maximum anchorage were divided into 2 groups according to maxillary posterior anchorage reinforcement: high-pull headgear, conventional transpalatal arch, and interarch elastics (n= 28); or modified transpalatal arch supported by 2 midpalatal miniscrews (n= 23). Bilateral maxillary first premolars were extracted in all patients. Pretreatment and posttreatment lateral cephalometric radiographs were superimposed to compare skeletal and dental changes between the groups. (1) The miniscrew group had less mesial movement of the maxillary first molars (0.85 vs 3.63 mm) and greater maxillary incisor retraction (6.87 vs 4.50 mm) than did the headgear group with the same treatment duration. (2) The maxillary molars were significantly intruded in the miniscrew group (1.30 mm), whereas they were extruded in the headgear group (0.71 mm). In the miniscrew group, intrusion of the maxillary molars resulted in a statistically significant decrease in the mandibular plane angle (0.80°). Patients using high-pull headgear showed no significant decrease in these measurements. In both the anteroposterior and vertical directions, a modified transpalatal arch supported by 2 midpalatal miniscrews provided more stable anchorage.

Correction of bilateral impacted mandibular canines with a lip bumper for anchorage reinforcement

Multiple treatment options are available to patients with impacted manibular canines in addition to a retained deciduous canine. This article describes the treatment of a prepubertal girl, aged 10 years 6 months, with a skeletal Class I, dental Class II Division 1 malocclusion, retrognathic mandible, deep overbite, proclined maxillary incisors, midline diastema, and bilateral mandibular canine impaction. The orthodontic treatment plan included extraction of the deciduous canine and forced eruption of the impacted canines. A modified lip bumper appliance was used both for forced eruption and to reinforce anchorage. Through the collaborative efforts of an orthodontist and an oral surgeon, an excellent esthetic and functional outcome was achieved.

Age‐related changes in maxillary and mandibular cortical bone thickness in relation to temporary anchorage device placement

The aim of this study was to investigate the correlation between alveolar bone cortical thickness (ABCT) and age in the maxillae and mandible in humans. This information could then be translated into clinical application with temporary anchorage devices (TADs) in orthdontics. Samples comprised 82 post-mortem CT datasets (41 males and 41 females) aged between 11 to 50 years, and were divided into five different age groups and gender. Alveolar ABCT was measured in the labial/buccal and palatal/lingual sides of the incisor, canine, premolar, molar and tuberosity/retromolar regions of the maxillae and mandible. Correlations between ABCT and age and gender were analysed with linear regression analysis. Strong correlation between ABCT and age was found for the maxilla on the labial side of the maxillary incisor region (p < 0.001). On the palatal aspect, significant correlations between ABCT and age were found in the maxillary incisor and maxillary premolar regions (p = 0.01 and p = 0.047 respectively). Significant correlation between ABCT and gender was found only at the buccal aspect of the maxillary molar region (p = 0.022). In the mandible, a statistically significant correlation between ABCT and age was found in the cortical bone of the labial side of the mandibular incisor region (p = 0.017). However, statistically significant negative correlation between ABCT and age was found in the mandibular canine region (p = 0.033). The only site to demonstrate a significant difference in change in ABCT with age between males and females was the lingual side of the retromolar region, in which female ABCT increased more than in males (slope = 0.015). There is minimal clinically significant correlation between ABCT and age at the alveolar bone level. Although investigations show statistically significant correlations, these may not be clinically significant as those regions are not ideal for anchorage reinforcement with TADs in orthodontic practice.

Three-dimensional retraction of anterior teeth with orthodontic miniplates in patients with temporomandibular disorder

Vertical dimension control is critical for adults with Class II high-angle malocclusions. If the patient has a temporomandibular disorder, this requirement is exacerbated. When extraction is planned, the treatment challenge is further increased. This article reports on a new biomechanical design (C-therapy) appropriate for anterior segment retraction with excellent control of the vertical dimension, even in a Class II high-angle patient with a temporomandibular disorder. Maximum retraction of the maxillary anterior segment can be achieved with a lingual retractor and a palatal miniplate without appliances on the maxillary posterior segments. Mandibular anterior vertical height was well controlled by a second miniplate in the mental region. This device also contributed to mandibular anchorage reinforcement. A patient with temporomandibular disorder symptoms treated with this approach is shown.

DETERMINING PULL – OUT DEFORMATIONS OF BONDED METAL ANCHORS EMBEDDED IN CONCRETE BY MEANS OF PHOTOGRAMMETRY

Abstract. Chemical anchorages are applied in many engineering implementations, particularly strengthening of reinforced concrete structures. During strengthening procedure; chemical anchorages should be tested, since they supply to transfer the load between existing construction elements and newly added elements. Therefore; the study of the quality of chemical anchorages is an important issue in construction materials science. In this context; the most important experiment is to determine the pull-out loads of embedded anchorage reinforcement by applying axial loads. In this study; it is aimed to determine the displacements of steel reinforcements, embedded into concrete by using chemical anchorages, while applying axial pulling loads. In order to determine the displacements and load – deformation graphs; starting conditions and every 10 bar pressure applied conditions of the steel reinforcements were captured by the cameras. The obtained images were evaluated by using photogrammetric software. Based on the photogrammetric post-processing results, the load – deformation graphs were plotted and the loads at loss of adhesion were determined.

Mini-screw implant or transpalatal arch-mediated anchorage reinforcement during canine retraction: A randomized clinical trial

To compare mesial movement of upper first molars during maxillary canine retraction using a pre-adjusted edgewise appliance provided by anchorage reinforcement and a transpalatal arch or mini-screw implant. Randomized clinical trial. Department of Orthodontics and Dentofacial Orthopedics, Armed Forces Medical College, Pune, India. From a cohort of subjects requiring the extraction of both upper first premolars and pre-adjusted edgewise appliances to correct their malocclusion, a total of 30 were randomly allocated to receive two different forms of anchorage reinforcement: group A--receiving mini-screw implant and group B--receiving a transpalatal arch Group A subjects received titanium mini-screw implants placed at the start of treatment between the maxillary second premolar and maxillary first molar. Maxillary second premolars were secured to the mini-screw implants using of 0.010-inch stainless steel ligature wire. Group B subjects received a custom-made transpalatal arch which was soldered to maxillary first molar bands. Active canine retraction was initiated in both groups on placement of a 0.019×0.025-inch stainless steel archwire using nickel titanium closed coil springs. Mesial movement of the upper first molars as measured on pre- (T1) and post-treatment (T2) lateral skull radiographs. The results showed that in group A the mean mesial movement of the first molars between T1 and T2 was 0.0 mm (SD 0.02; P = 0.90), whereas in Group B there was a mean forward movement of the first maolars of 2.48 mm (SD 0.71; P<0.001). In this trial, mini-screw implants placed prior to levelling and aligning were able to provide absolute anchorage during maxillary canine retraction, in contrast to a transpalatal arch.

Patient with nonsyndromic bilateral and multiple impacted teeth and dentigerous cysts

This article reports the successful treatment of a patient with the unusual occurrence of bilateral and multiple dentigerous cysts of the premolars. One impacted mandibular premolar was moved by traction orthodontically. On the opposite side, the impacted premolar was autotransplanted after space was created through mesial movement and hemi-sectioning of the neighboring molars. The impacted maxillary premolar was extracted. Miniscrews were additionally used for anchorage reinforcement to prevent unintended counteractions and solve the problem of space management after autotransplantation. We also reviewed the clinical implications of the diagnosis, planning, and treatment of cyst-associated impacted teeth in young adult patients.

Concrete Roadside Barrier Anchorage Details for 5-in., Cast-in-Place Decks on Prestressed Beams

The Texas Department of Transportation commonly builds bridge spans with adjacently framed, prestressed box beams and slab beams and makes them composite with a 5-in.-thick, concrete, cast-in-place deck (CIPD). The presence of a cast-in-place, concrete overlay allows use of more favorable empirical, live-load distribution equations, which results in more efficient bridge spans. This 5-in.-thick CIPD offers limited depth for anchorage of rail reinforcement. AASHTO Load and Resistance Factor Design Bridge Design Specifications has a limiting hook development length of 6 in. for a No. 4 rail anchorage. With a 5-in. deck thickness and a 6-in. minimum required development length, the rail anchorage reinforcement must be cast in the pretensioned beams to meet specification requirements for rail anchorage strength. This need has made it difficult to ensure adequate development of the rail anchorage reinforcement. The objective of the study reported here, therefore, was to develop barrier anchorage details that would meet the AASHTO Manual for Assessing Safety Hardware (MASH) evaluation criteria, minimize damage to the concrete barrier profile and CIPD, and prevent delamination of the CIPD from the precast beams, which was witnessed in a research project performed at Texas Transportation Institute. The anchorage modifications were evaluated successfully under the Manual for Assessing Safety Hardware Test 3–11 and were considered suitable for roadways with traffic conditions appropriate for Testing Level 3 safety hardware.

Clinical Effectiveness of Orthodontic Miniscrew Implants: a Meta-analysis

The aim of this meta-analysis was to examine the clinical effectiveness of miniscrew implants (MI) used for anchorage reinforcement compared with that of conventional orthodontic means, as well as to assess the success rates of MIs and the possible risk factors affecting their clinical effectiveness. Literature searches were conducted, and, using specific inclusion and exclusion criteria, two independent investigators performed data extraction and analysis. Overall pooled estimates with 95% confidence intervals (CI) were obtained with the random-effects model. Eight out of 3183 original papers met the inclusion criteria. The mean difference of anchorage loss between the MI and conventional anchorage group was −2.4 mm (95% CI = −2.9 mm to −1.8 mm, p = 0). MIs significantly decreased or negated loss of anchorage. Anchorage loss seemed to be less in the mandible, when the MIs were inserted between the second premolar and the first molar, when 2 MIs were inserted per patient jaw, when they were directly connected, as well as when treatment lasted more than 12 months. MIs presented a success rate of 87.7%, with no significant differences between the various subgroups. However, the results of this meta-analysis should be interpreted with some caution because of the number, quality, and heterogeneity of the included studies.