Effectiveness of non-conventional methods for accelerated orthodontic tooth movement: a systematic review and meta-analysis.

JJOD-2331; No. of Pages 20 journal of dentistry xxx (2014) xxx–xxx

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Effectiveness of non-conventional methods for accelerated orthodontic tooth movement: A systematic review and meta-analysis Nikolaos Gkantidis a,*, Ilias Mistakidis b, Thaleia Kouskoura a, Nikolaos Pandis a a

Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Freiburgstrasse 7, CH-3010 Bern, Switzerland b Department of Orthodontics, School of Health Sciences, Faculty of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece

article info

abstract

Article history:

Objectives: To assess the available evidence on the effectiveness of accelerated orthodontic

Received 17 April 2014

tooth movement through surgical and non-surgical approaches in orthodontic patients.

Received in revised form

Methods: Randomized controlled trials and controlled clinical trials were identified through

23 May 2014

electronic and hand searches (last update: March 2014). Orthognathic surgery, distraction

Accepted 15 July 2014

osteogenesis, and pharmacological approaches were excluded. Risk of bias was assessed

Available online xxx

using the Cochrane risk of bias tool. Results: Eighteen trials involving 354 participants were included for qualitative and quantita-

Keywords:

tive synthesis. Eight trials reported on low-intensity laser, one on photobiomodulation, one on

Orthodontics

pulsed electromagnetic fields, seven on corticotomy, and one on interseptal bone reduction.

Accelerated tooth movement

Two studies on corticotomy and two on low-intensity laser, which had low or unclear risk of

Corticotomy

bias, were mathematically combined using the random effects model. Higher canine retrac-

Low-level laser therapy

tion rate was evident with corticotomy during the first month of therapy (WMD = 0.73; 95% CI:

Systematic review

0.28, 1.19, p < 0.01) and with low-intensity laser (WMD = 0.42 mm/month; 95% CI: 0.26, 0.57,

Meta-analysis

p < 0.001) in a period longer than 3 months. The quality of evidence supporting the interventions is moderate for laser therapy and low for corticotomy intervention. Conclusions: There is some evidence that low laser therapy and corticotomy are effective, whereas the evidence is weak for interseptal bone reduction and very weak for photobiomodulation and pulsed electromagnetic fields. Overall, the results should be interpreted with caution given the small number, quality, and heterogeneity of the included studies. Further research is required in this field with additional attention to application protocols, adverse effects, and cost-benefit analysis. Clinical significance: From the qualitative and quantitative synthesis of the studies, it could be concluded that there is some evidence that low laser therapy and corticotomy are associated with accelerated orthodontic tooth movement, while further investigation is required before routine application. # 2014 Elsevier Ltd. All rights reserved.

* Corresponding author. Tel.: +41 031 632 25 91; fax: +41 031 632 98 69. E-mail address: [email protected] (N. Gkantidis). http://dx.doi.org/10.1016/j.jdent.2014.07.013 0300-5712/# 2014 Elsevier Ltd. All rights reserved.

Please cite this article in press as: Gkantidis N, et al. Effectiveness of non-conventional methods for accelerated orthodontic tooth movement: A systematic review and meta-analysis. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.07.013

JJOD-2331; No. of Pages 20

2

journal of dentistry xxx (2014) xxx–xxx

1.

Introduction

Reduced treatment duration is important for care providers and orthodontic patients. It is also desirable that aesthetic concerns1 and time dependent adverse events such as discomfort, pain, external apical root resorption, suboptimal oral hygiene, white spot lesions and dental caries2 are held to the minimum. Empirical evidence has indicated that 2 years is a representative of average orthodontic treatment duration with a significant variation which can be influenced by several factors including case severity, extraction versus non-extraction therapy, need for orthognathic surgery, clinical expertise, and patient cooperation.3,4 Tooth movement induced by a physical stimulus/force consists of a series of phenomena involving biologic reactions of the alveolar bone, the periodontal ligament (PDL), the gingiva, and the vascular and neural networks.5 Under applied force the stress–strain distribution in the PDL is altered and tension and compression sites develop. A series of events resembling inflammation are initiated and regional osteoclastic and osteoblastic activity is observed leading to bone resorption and apposition that results in tooth movement through modelling–remodelling of the alveolar bone.6 Adjunct to the proper selection of brackets, wires, embiomechanic systems, force levels, and anchorage systems, an array of novel techniques has been introduced to accelerate orthodontic tooth movement. These techniques can be briefly categorized as surgical and non-surgical. The surgical category includes alveolar decortication, corticotomy, distraction of the periodontal ligament, and distraction of the dento-alveolus.7 The idea of surgically accelerated tooth movement although more than a century old8 has only gained momentum and interest during the last 10 years.9,10 Theoretically, selective surgical alveolar bone reduction induces a localized increase in turnover of alveolar cancellous bone, suggesting a possible mechanism underlying the observed acceleration of tooth movement.11 Another possible mechanism could be attributed to the removal of the hyaline zone formed soon after force application, which allows earlier bone resorption required for tooth movement.12 Non-surgical techniques include low-intensity laser irradiation,7,13 resonance vibration,14 pulsed electromagnetic electrical currents,16 and pharmacological fields,15 approaches.17 Low laser therapy is reported to stimulate osteoblast and osteoclast cell proliferation, and enhance the velocity of tooth movement due to accelerated bone remodelling mediated by the RANK/RANKL/OPG system.18 Resonance vibration is also advocated to act through enhanced RANKL expression in the periodontal ligament.14 Over the years, several case reports, narrative reviews, and clinical research papers have discussed various aspects of techniques used for accelerated orthodontic tooth movement. The only systematic evaluation of all methods used on this rapidly moving field included a limited number of studies that were published until August 2011.19 Thus, a thorough systematic evaluation of the most recent clinical evidence related to accelerated orthodontic treatment is missing from

the literature. The purpose of the present systematic review is to critically assess and systematically summarize the available evidence regarding clinical performance of surgical and non-surgical approaches for accelerated orthodontic tooth movement.

2.

Materials and methods

The PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) reporting guidelines are followed in the systematic review.20,21 A pilot Pubmed search followed by systematic evaluation of five potentially eligible randomly selected studies was performed in order to prepare the study protocol. Data extraction forms were constructed after the initial results of the pilot search. The interventions for accelerated orthodontic tooth movement are relatively unexplored. It was, therefore, decided to consider for inclusion eligibility also non-randomized studies.

2.1.

Search strategy

Electronic search was conducted independently by two authors (T.K. and I.M.) in four major databases, Pubmed, EMBASE, Google scholar beta, and all Cochrane Databases, at the end of March 2014 with no time restrictions. A specific search was performed to identify any relevant study, based upon various combinations of key words. A detailed description of the electronic search strategy applied to all the electronic databases used for the study is provided in Appendix 1. The references of all retrieved full text papers were searched for relevant papers that might have been missed through the electronic search. Unpublished literature was not excluded from the present study, since it was searched through Cochrane Central Register of Controlled Trials and Google scholar beta. When additional or missing information on methods or results was needed, corresponding authors were contacted for clarifications. Eligibility assessment was performed in a standardized manner and independently by two reviewers (T.K. and I.M.) who were not blinded to the identity of the authors, their institution, or the results of the research. Any disagreement was resolved by consensus and through discussion with a third reviewer (N.G.). Titles and abstracts were screened first and afterwards full text review of any relevant and potential for inclusion article was conducted. A positive exclusion method was used, whereby only those publications that did not meet one or more of the inclusion criteria were excluded. An independent reviewer (N.P.) checked a random selection (20%) of filtered articles for consistency. Inter-rater agreement on study eligibility was assessed by Cohen’s kappa.

2.2.

Eligibility criteria

The following inclusion criteria were applied: 1. Randomized controlled trials (RCTs) and controlled clinical trials (CCTs) reporting on results or treatment parameters related to accelerated orthodontic tooth movement.



2. English, German, French, and Italian languages. The exclusion criteria were: 1. 2. 3. 4.

In vitro and animal studies. Case reports/case series. Studies with sample size less than six. Editorials, opinions, reviews, and technique description articles, without reported sample. 5. Studies referring to accelerated tooth movement occurring as a result of orthognathic surgery, distraction osteogenesis procedures, or pharmacological approaches.

2.3.

Types of interventions

Any intervention used to accelerate orthodontic tooth movement. Approaches that are considered refinements of conventional orthodontic treatment, such as selection of brackets, wires, biomechanical systems, force levels, and anchorage systems were not considered. Moreover, pharmacological approaches and distraction osteogenesis techniques were excluded from the study.

2.4.

Control

Comparable patients receiving an alternative accelerating intervention or conventional orthodontic treatment. Comparable patients receiving different accelerating regimens or application techniques (i.e. different laser irradiation regimens, different corticotomy techniques etc.) were also considered.

2.5.

Types of participants

Healthy subjects who require orthodontic treatment with fixed appliances with no age limit. Studies including patients receiving any kind of medication, which can affect orthodontic treatment or patients receiving orthognathic surgery, syndromic patients, patients with cleft lip and palate or any systemic disease were excluded.

2.6.

Types of outcome measures

Any measure of performance or effectiveness of methods intending to accelerate tooth movement. The primary collected outcome measures were rate of tooth movement or cumulative distance of movement, duration of orthodontic treatment or a predefined part of it, or time needed to complete a predefined tooth movement. The influence of interventions on patients’ quality of life was also considered. Potential adverse effects were evaluated as secondary outcomes.

the original studies were re-examined by the two reviewers and a 3rd author (N.G.) reconciled any disagreements. Author N.G. was responsible for checking the data extraction forms. Inter-rater agreement on data extraction was assessed by Cohen’s kappa. In brief, the following information was obtained from each included study: (a) general information, (b) study characteristics, (c) patient sample characteristics, (d) intervention and setting, (e) outcome data/results.

2.8.

Quality assessment of individual studies

The quality assessment of the eligible studies was performed by two investigators, independently (T.K. and N.G.). In areas of disagreements, a joint decision was obtained after thorough discussion by all authors and finally consensus was achieved. Quality assessment of randomized studies was performed using the Cochrane Risk of bias tool.22 The same tool was also used for non-randomized studies in the applicable domains.

2.9.

Data synthesis

Clinical heterogeneity of included studies was gauged by assessing the treatment protocol, including participants and setting, materials used, interventions applied, timing of data collection and measurement techniques. Statistical heterogeneity was to be assessed by inspecting a graphical display of the estimated treatment effects from the trials in conjunction with 95% confidence intervals. The Chi-square test was used to assess heterogeneity.23 A weighted treatment effect (WMD; weighted mean difference) was calculated with associated 95% confidence intervals using a random-effects model; a random-effects model was considered more appropriate in view of the variation in population and settings. One of the primary outcomes assessed was the amount of tooth movement in millimetres per month. This outcome was calculated in each primary study by dividing the amount of tooth movement by the number of days of follow-up, and then scaled to provide a monthly rate. The majority of the included trials were split-mouth and for those the mean difference was calculated between quadrants and the standard deviation of the difference was approximated with the following formula: qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi sd21 þ sd22 2 r sd1 sd2 where sd1 and sd2 are the standard deviations between quadrants, respectively, and r is the correlation coefficient between quadrants. The correlation coefficient was set at 0.5 for splitmouth designs and at 0 for parallel designs.24 If more than 10 studies were included in meta-analysis, standard funnel plots and contoured enhanced funnel plots were to be drawn in order to explore publication bias.

2.10. 2.7.

3

Sensitivity analysis

Data extraction process

Data extraction was performed by two authors (T.K. and I.M.), independently in the pre-determined data abstraction forms that were also used for quality assessment of the included studies. The data forms were constructed by one author, based on the findings of the pilot search. In cases of inconsistencies,

Sensitivity analyses were pre-specified to deal with publication bias and other potential sources of heterogeneity including dominant effects of one or more large studies and differences in outcome related to specific interventions to isolate their influence on the overall outcome. Meta-analyses and sensitivity analyses were undertaken in STATA version



4


13.1TM (STATA Corporation, College Station, USA) using the ‘metan’ command.

was implemented in order to assess the level of the existing evidence.25

2.11. Determination of available evidence supporting clinical recommendations

3.

Results

3.1.

Literature flow

Following the quality assessment of individual articles, each one was assigned to a group according to the studied subject. For each subject category, the overall strength of the body of evidence was assessed after considering the quality (assessment of individual studies), quantity (magnitude of treatment effect, number of studies, sample size across studies), and consistency (the extent of similarity between different studies in their findings) of the available studies and their findings on the subject. Clinical recommendations were formulated based on these considerations and by balancing the desirable and undesirable consequences of each intervention. For the meta-analysis findings the GRADE approach

The flow diagram of study selection is shown in Fig. 1. The literature search initially yielded 648 records. Following review of the titles and abstracts, it was decided that 52 studies should be examined in more detail. Thirty-four of the 52 studies were subsequently excluded following full-text reading of the article due to various reasons described in the chart. Finally, 18 papers were included in the review for qualitative and quantitative synthesis (Table 1). The kappa scores for the selection and data extraction procedures were 0.86, and 0.91, respectively.

Fig. 1 – The flow diagram of study selection. Please cite this article in press as: Gkantidis N, et al. Effectiveness of non-conventional methods for accelerated orthodontic tooth movement: A systematic review and meta-analysis. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.07.013


Study

Subject group

Main objective

Study design

Treatments tested

Sample description (size, sex, age)

Effect on duration of nonextraction orthodontic treatment Effect on rate of space closure

Prospective CCT

Low-intensity laser vs. conventional treatment

Exp.: 23 (12F, 11M; 25.3 2.8 years) control: 22 (14F, 8M; 25.6 2.5 years)

Skeletal and dental Class I, crowding 5 mm

Consecutive/ consecutive

RCT (split mouth)


Exp. and control: 11 (sex NA; 12– 18 years)

Crowding or bimaxillary protrusion

Random/unclear, based on specific criteria

Malocclusion characteristics

Method of allocation/recruitment procedure used

Camacho and Cujar (2010)26

Low-intensity laser (treatment duration)

Cruz et al. (2004)13

Low-intensity laser (maxillary canine retraction)

Limpanichkul et al. (2006)29


Effect on rate of canine retraction

RCT (split mouth)


Exp. and control: 12 (8F, 4M; 20.11 3.4 years)

Unclear


Youssef et al. (2008)31

Low-intensity laser (maxillary and mandibular canine retraction)

Effect on rate of space closure

Prospective CCT (split mouth)


Exp. and control: 15 (sex NA; 14– 23 years)


By side (left control, right exp.)/unclear, based on specific criteria

Sousa et al. (2011)30

Low-intensity laser (maxillary and/or mandibular canine retraction)


RCT (split mouth)


Exp. and control: 10 (6F, 4M; 10.5– 20.2 years)



Doshi-Mehta et al. (2012)27



RCT (split mouth)


Exp. and control: 20 (12F, 8M; 12– 23 years)

Unclear


Genc et al. (2013)28

Low-intensity laser (maxillary lateral incisor retraction)

Effect on rate of retraction




Convex profile or crowding

By side (left control, right experimental)/ unclear, based on specific criteria

Dominguez et al. (2013)32

Low-intensity laser (maxillary 1st premolar retraction)





Lack of space in the upper arch

By side (left control, right experimental)/ Consecutive, based on specific criteria

Details of the acceleration protocol Photon Lase III (830 nm, 80 J) for 22 s buccally and 22 s palatally at each single tooth. Applied 24 h after the 1st control and thereafter at every appointment Ga-Al-As laser (780 nm, 20 mW) for 10 s, 5 times buccal/5 times palatal, on the cervical 1/3 mesial and distal, on the apical 1/3 mesial and distal and on the middle, on days 0, 3, 7, 14, 30, 33, 37, 44 Ga-Al-As laser (860 nm, 100 mW) at three sites on buccal and on palatal sides, and at two sites distal to the canine (23 s/site) on the 1st, 2nd and 3rd day after initiation of retraction. Repetition of the 3-day protocol after 1, 2 and 3 months Ga-Al-As laser (809 nm, 100 mW) for 10, 20 and 10 s at cervical, middle and apical areas respectively on days 0, 3, 7, and 14 after every activation As-Ga-Al laser (780 nm, 20 mW) for 10 s, at 10 sites per tooth (5 bucally/5 lingually) on days 0, 3 and 7 after the first application (T1) and every reactivation (T2 and T3) using the same 3-day protocol Ga-Al-As laser (808 nm) for 10 s, 5 times buccal/5 times palatal on the cervical 1/3 mesial and distal, on the apical 1/3 mesial and distal, and on the middle, on days 3,7, 14 and thereafter every 15th day Ga-Al-As laser (808 nm, 20 mW) for 10 s, 5 times buccal/5 times palatal, on the cervical 1/3 mesial and distal, on the apical 1/3 mesial and distal and on the middle, on days 0, 3, 7, 14, 21, 28 Diode laser (PeriowaveTM; 670 nm, 200 mW) partially inserted into the periodontal pocket and moved all along the sulcus, applied distally, buccally, and lingually, 3 min on each surface (total 9 min) on days 0, 1, 2, 3, 4, and 7



Table 1 – Characteristics of included studies grouped according to the main technique applied for acceleration of orthodontic tooth movement: (a) low intensity laser, (b) photobiomodulation, (c) pulsed electromagnetic fields, (d) corticotomy, and (e) interseptal bone reduction.

5

Study

Subject group

Main objective

Study design

Treatments tested




Photobiomodulation (levelling and alignment in the maxilla and/or the mandible)

Effect on time needed for alignment

Prospective CCT

Photobiomodulation vs. conventional treatment

n: 90 (exp: 73, control:17) (62F, 28M; 18 7 years)

Class I with Little’s irregularity index > 2 mm

Unclear/consecutive

Showkatbakhsh et al. (2010)15

Pulsed electromagnetic fields (maxillary canine retraction)

Effect on amount of space closure

RCT (split mouth)

Pulsed electromagnetic fields vs. conventional treatment

Exp. and control: 10 (5F, 5M; 23 3.3 years)

5 Class I and 5 Class II div.1 patients with symmetrical crowding


Aboul-Ela et al. (2011)33

Corticotomy perforations (maxillary canine retraction)


RCT (split mouth)

Corticotomy vs. conventional treatment

Exp. and control: 13 (8F, 5M; mean 19 years)

Class II div. 1 with increased overjet


Alikhani et al. (2013)9



RCT (and split mouth in exp. group)


Exp.: 10 (5F, 5M; mean 26.8 years) control: 10 (7F, 3M; mean 24.7 years)

Class II div. 1 with overjet 10 mm


Abed and Al-Bustani (2013)36

Corticotomy perforations (maxillary canine retraction) Corticotomy (positioning of palatally impacted canines)




Exp. and control: 12 (8F, 4M; 17–28 years)

Unclear

By the size of space (experimental on the largest space)/unclear

Effect on time needed for positioning of palatally impacted canines on dental arch Effect on time needed for crowding correction, periodontal parameters, root length, and bone density

RCT (split mouth)


Exp. and control: 6 (4F, 2M; 11.1– 12.9 years)

Bilateral palatally impacted canines

Random/consecutive

RCT


Exp.: 10, control: 10 (17F, 3M; 18.4– 25.6 years)

Lower anterior crowding 3–5 mm, skeletal Class I


Fischer (2007)35

Shoreibah et al. (2012a)38

Corticotomy (lower anterior crowding correction)

Near-infrared light device (850 nm, 60 mW/cm2) worn by patients at home for 20 or 30 min/day or 60 min/week. Target area was the alveolus of both the maxilla and mandible An integrated circuit I.C. (Intersil, NE555) embedded in acrylic appliance and generated an electromagnetic field of 0.5 mT, 1 Hz that was applied to the canine only for 8 h daily, overnight Scattered corticotomy perforations (No 2 round bur, low-speed hand piece) that approximated the width of the buccal cortical bone and extended from the lateral incisor to the first premolar area Three corticotomy perforations (1.5 mm wide and 2–3 mm deep) performed along a vertical line at equal distances from the canine and the 2nd premolar before the retraction using a disposable device (PROPEL Orthodontics, Ossining, NY), without any flap 3–4 corticotomy perforations performed mesially and distally to the canine, with a 1.5 mm round bur, spaced 2 mm apart Corticotomy perforations (11/ 2 mm round bur) along the bone mesial and distal to the impacted tooth, approximately 2 mm apart and extended into the edentulous area into which the tooth was to be moved Vertical cuts through the labial cortical bone (small round bur) between all teeth from canine to canine, started 1–2 mm below the alveolar crest and extended 1–2 mm below the apices of the teeth


Kau et al. (2013)40

Details of the acceleration protocol


6


Table 1 (Continued )


Study

Subject group

Main objective

Study design

Treatments tested




Details of the acceleration protocol Vertical cuts through the labial cortical bone (small round bur) between all teeth from canine to canine, started 1–2 mm below the alveolar crest and extended 1–2 mm below the apices of the teeth. In the bone graft group, bioactive glass mixed with blood from the surgical site was applied directly over the bleeding buccal bone prior to flap repositioning Piezoelectric group: vertical cuts (insert 511) mesial and distal along each tooth root from 7 to 7 and corticotomy perforations (insert 514) spread between them Conventional group: same protocol applied with a round multi-blade bur and a high speed handpiece The extraction socket of the maxillary first premolar was deepened to the canine apex, and the interseptal bone distal to the canine was reduced to 1 to 1.5 mm thickness using carbide burs, without flap surgery. If present, the interradicular septal bone of the socket was also removed. The extraction socket was surgically widened in the buccopalatal dimension, while the alveolar crest of interseptal bone was left untreated

Shoreibah et al. (2012b)37


Effect of bone grafting on time needed for crowding correction, periodontal parameters, root length, and bone density

RCT

Corticotomy with vs. without bone grafting

Exp.: 10, control: 10 (16F, 4M; mean age 24.5 years)

Lower anterior crowding 3–5 mm, skeletal Class I


Cassetta et al. (2012)34

Corticotomy using piezo vs. round burs (surgery duration and quality of life)

Duration of surgery and oral health-related quality of life (OHRQoL) in piezoelectric surgery and rotatory osteotomy

RCT

Piezoelectric surgery vs. conventional rotary osteotomy

Exp.: 12 (6 piezo, 6 rotatory) (8F, 4M; 13–17 years)

Bilateral Class I molar occlusion with a moderate-severe crowding or/and unilateral crossbite

Random/based on specific criteria

Leethanakul et al., 201439

Interseptal bone reduction (maxillary canine retraction)


RCT (split mouth)

Interseptal bone reduction vs. conventional treatment

Exp. and control: 18 (18F, 21.9 4.7 years)

Unclear





Exp.: experimental group.

7


8


3.2.

Description of studies

From the 18 included studies, eight tested the effect of application of low intensity laser on orthodontic tooth movement13,26–32 and seven studies evaluated corticotomyassisted orthodontic treatment.9,33–38 The effects of interseptal bone reduction,39 pulsed electromagnetic fields15 and photobiomodulation40 were investigated by a single trial each. An overview of the characteristics of the included trials is provided in Table 1.

3.3.

Publication bias

Statistical analysis of publication bias was not indicated, as less than 10 studies were included in all the quantitative syntheses undertaken.

3.4.

Risk of bias of included studies

For non-randomized studies, the items of random sequence generation and allocation concealment were not applicable and were set by default as unclear. This decision was based on the specific characteristics of the clinical question studied; primarily the inability of personnel to predict favourable versus unfavourable response to treatment. An overview of the results of individual studies, the overall risk of bias assessment, and a narrative report of the results can be found in Table 2. Initial inter-rater disagreement existed in 4 out of 18 cases (agreement > 75%) and these were all between unclear and high risk ratings. Disagreements were resolved through discussion by all authors until consensus was reached.

3.5.

RCTs

Fig. 2 shows the summary of risk of bias assessment for RCTs according to the Cochrane Risk of bias tool. From the 12 RCTs included, two were assessed as low,27,29 five as unclear,9,30,33,35,39 and five as high overall risk of bias13,15,34,37,38 (Table 2).

3.6.

Prospective CCTs

From the six CCTs included, three were assessed as unclear26,31,32 and three as high overall risk of bias.28,36,40 Fig. 3 shows the assessment of risk of bias for non-randomized CCTs.

3.7.

Quantitative synthesis of included studies

Overall 10 studies were deemed to be at low/unclear risk of bias and were initially considered appropriate for quantitative synthesis.9,26,27,29–33,35,39 From those, two studies evaluating corticotomy assisted canine retraction rate9,33 and four studies evaluating application of low-intensity laser on rate of canine retraction27,29–31 were considered appropriate for attempting meta-analysis. Calculation of predictive intervals was not possible since it requires larger number of low risk of bias studies.41 The results of Camacho and Cujar26 could not be pooled due to different outcome measures (overall duration of

non-extraction treatment). Likewise, the study of Fischer35 investigated the effect of corticotomy on positioning of palatally impacted canines, the study of Dominguez et al.32 the effect of low-intensity laser on 1st premolar retraction rate and the study of Leethanakul et al.39 an intervention based on interseptal bone reduction. Thus, their results could not be pooled.

3.7.1. Effects of interventions 3.7.1.1. Corticotomy. Two trials could be mathematically combined for this intervention for a one-month follow up period.9,33 In total 23 patients were included. Both trials measured actual canine retraction in a first premolar extraction space; no anchorage loss in terms of mesial movement of posterior segments was expected, since retraction was performed through direct traction from mini-screws. The random effects model assumes that there are different rates of tooth movement in different settings; the calculated estimate therefore indicates the average effect. Meta-analysis of these studies was suggestive of higher tooth movement rate by 0.73 mm/month with corticotomy versus the control technique for the first month of retraction (Fig. 4: WMD = 0.73; 95% CI: 0.28, 1.19, p < 0.01). The 95% CI indicates that the mean effect size may range from 0.28 mm/month to 1.19 mm/month in favour of corticotomy. Heterogeneity was moderate I2 = 46.9%, p = 0.17, t2 = 0.07). According to GRADE the overall quality of evidence supporting this intervention is low (Table 3).

3.7.1.2. Low-intensity laser. The effect of low-intensity laser was initially assessed in two studies eligible for quantitative synthesis.27,30 Both studies measured the rate of 1st premolar extraction space closure; both actual canine retraction and anchorage loss in terms of mesial movement of posterior segments. In total 30 patients were included for an overall follow up period of at least three months to the time until complete space closure was achieved at one site. Metaanalysis of these studies was suggestive of higher tooth movement rate with low-intensity laser versus the control technique (Fig. 5: WMD = 0.42; 95% CI: 0.26, 0.57, p < 0.001). Heterogeneity was high I2 = 75.2%, p = 0.05, t2 = 0.001). The overall quality of evidence supporting this intervention is moderate (Table 4). In the context of a sensitivity analysis two further metaanalyses were undertaken to gauge the inclusion of the studies by Limpanichkul et al.29 and Youssef et al.31 on the outcome. Limpanichkul et al. utilized a quite different laser application protocol compared to the other studies that measured actual canine retraction in the 1st premolar extraction space; also no anchorage loss was expected in this study (Table 1). The effect of the intervention changed to marginally non-significant (Fig. 6: WMD = 0.28; 95% CI: 0.02, 0.59, p = 0.07). Statistical heterogeneity increased to an unacceptable level (I2 = 97.5%, x2: p < 0.001, t2 = 0.07). The Youssef et al. trial which displayed the largest effect was examined in another sensitivity metaanalysis. The effect of low-intensity laser on tooth movement remained significant; however the imprecision of the effect measure increased (Fig. 6: WMD = 0.62; 95% CI: 0.16, 1.08, p = 0.01). Statistically, heterogeneity also in this case increased to an unacceptable level (I2 = 98.8%, Chi-square: p < 0.001, t2 = 0.16).



Study

Subject group

Definition of pre-specified main outcome

Camacho and Cujar (2010)26

Low-intensity laser (treatment duration)

Time required to complete orthodontic treatment

Cruz et al. (2004)13


Amount of space closure obtained after 2 months

Limpanichkul et al. (2006)29


Amount of retraction obtained after 3 months

Youssef et al. (2008)31

Low-intensity laser (maxillary and mandibular canine retraction)

Rate of space closure to complete closure of the extraction space

Sousa et al. (2011)30

Low-intensity laser (maxillary and/or mandibular canine retraction) Low-intensity laser (maxillary canine retraction)

Amount of space closure obtained after 3 months

Genc et al. (2013)28

Low-intensity laser (maxillary lateral incisor retraction)

Amount of retraction obtained after 35 days

Dominguez et al. (2013)32

Low-intensity laser (maxillary 1st premolar retraction)

Amount of space closure obtained after 45 days

Doshi-Mehta et al. (2012)27

Space closure distance and rate upon the completion of retraction on experimental quadrant (4.5 months)

Summary outcome data Treatment duration exp.: 398 88 days, control: 565 130 days, p < 0.001 Space closure in 2 months exp.: 4.4 0.3 mm control: 3.3 0.2 mm, p < 0.001 Canine retraction at 3 months exp.: 1.3 0.2 mm control: 1.2 0.2 mm, p = 0.57 Space closure rate up to complete closure (mm/ month) exp.: 2.0 0.1, control: 1.0: 0.1, p < 0.001 Space closure at 3 months exp.: 3.09 1.06 mm, control: 1.60 0.63 mm, p < 0.001 Space closure at the end of retraction on exp. side exp.: 5.5 1.0 mm, control: 4.0 1.0 mm, p < 0.001 Rate of retraction (mm/ month) exp.: 1.1 0.2, control: 0.8 0.2, p < 0.01 Lateral incisor retraction after 35 days (approximation based on figure) exp.: 2.4 mm, control: 1.7 mm, p < 0.001 Space closure after 45 days exp.: 3.7 1.1 mm, control: 2.7 0.9 mm, p < 0.05

Additional outcomes

Quality assessmenta

NA

Unclear risk

NA

High risk

NA

Low risk

Pain intensity was significantly lower in the lased group than in the control group throughout the retraction period No statistically significant difference in root resorption or alveolar bone height

Unclear risk

The pain score on the experimental side was significantly lower compared with the control side on day 3 as well as on day 30 after start of canine retraction

Low risk

NA

High risk

No significant difference in plaque index and bleeding index. Slight pain reduction (though not significant) and slightly increased levels of RANKL and RANKL/OPG ratio in the gingival crevicular fluid of the laser group

Unclear risk

Unclear risk



Table 2 – Results of individual studies, overall quality assessment, and synthesis of results.

9

Study

Subject group


Summary outcome data

Additional outcomes

Quality assessmenta

Rate of alignment until irregularity was 1 mm

Rate of alignment (mm/ week) exp.: 1.1 1.0, control: 0.5 0.4, p < 0.001

NA

High risk

Amount of space closure until Class I canine relationship in either of the canines

NA

High risk

Aboul-Ela et al. (2011)33


Rate of retraction after 4 months

No statistically significant difference in plaque index, probing depth, attachment level, and gingival recession. Gingival index was slightly higher on the operated side

Unclear risk

Alikhani et al. (2013)9


Rate of retraction after 1 month

Space closure until canine Class I exp.: 5.0 1.3 mm, control: 3.5 1.6 mm, p < 0.001 Canine retraction rate (mm/ month) 1st month exp.: 1.9, control: 0.7 2nd month exp.: 1.8, control: 0.9 3rd month exp.: 1.1, control: 0.9 4th month exp.: 0.9, control: 0.8 p 0.01 for total observation time Canine retraction after 28 days: exp.: 1.1 0.2 mm control: 0.5 0.2 mm, p < 0.05

Unclear risk

Abed and Al-Bustani (2013)36


Rate of retraction after 1 month

Canine retraction after 1 month: exp.: 1.74 0.47 mm control: 1.22 0.40 mm, p < 0.005

Fischer (2007)35

Corticotomy (positioning of palatally impacted canines)

Canine movement rate until the tips of both canine crowns were properly positioned

Canine movement rate (mm/ week) exp.: 0.26 0.04 control: 0.19 0.01, p < 0.001

No difference between groups in pain and discomfort 1, 7, and 28 days after retraction. Inflammatory markers in gingival cervicular fluid were increased in the exp. group No difference in anchorage loss between surgical and non-surgical sides. No difference on gingival sulcus depth and tooth vitality preand post-surgery NA

Showkatbakhsh et al. (2010)15

High risk

Unclear risk


Photobiomodulation (levelling and alignment in the maxilla and/or the mandible) Pulsed electromagnetic fields (maxillary canine retraction)

Kau et al. (2013)40


10




Study

Subject group


Shoreibah et al. (2012a)38


Time needed for lower anterior crowding correction

Mean treatment duration exp.: 17.5 2.8 weeks control: 49 12.3 weeks, p < 0.05

Shoreibah et al. (2012b)37


Time needed for lower anterior crowding correction

Mean treatment duration exp. (+bone graft): 16.7 (14– 20) weeks control (bone graft): 17 (14– 20) weeks, ns

Cassetta et al. (2012)34

Corticotomy using piezo vs. round burs (surgery duration and quality of life)

Time required for intervention. Effect on the OHRQoL 3 and 7 days after surgery

Leethanakul et al. (2014)39

Interseptal bone reduction (maxillary canine retraction)

Rate of retraction after 3 months

Mean time Piezo: 34.3 (32.6–35.3) min, rotator: 28.2 (27.1–29.2) min, p > 0.05; OHRQoL baseline: 6.3 (0–14) 3 days; Piezo: 22.7 (7–45), rotator: 21.33 (16–26), p = 0.86 7 days; Piezo: 16.3 (2–25), rotator: 10.7 (5–22) p = 0.35 Canine retraction rate (mm/ month) 1st month exp.: 1.6 1.1, control: 0.9 0.3, p 0.005 2nd month exp.: 2.3 1.1, control: 1.2 0.5, p 0.005 3rd month exp.: 1.6 0.8, control: 1.3 0.7, p 0.01

Details on risk of bias assessment can be found in Fig. 2 for RCTs and Fig. 3 for CCTs.

Additional outcomes

Quality assessmenta

No difference in probing depth on controls. The exp. group showed an increase of 0.58 mm, from pre- to 6 months post treatment. Bone density and root length decreased from pre- to 6months post-treatment in a similar way for both groups Probing depth decreased significantly from pre- to 6months post-treatment by approximately 0.5 mm in both groups. Bone density decreased in the control group by 17.6 5.8% from pre- to 6-months posttreatment, while it increased by 25.9 15.6% in the bone graft group. Root length decreased by approximately 0.5 mm from pre- to 6months post-treatment in both groups NA

High risk

No difference in tipping or rotation per mm of canine movement in the two groups. The surgical site (left or right) and the two surgeons had no significant correlation with the total extent of canine movement

Unclear risk

High risk

High risk

11

a

Summary outcome data





12


Fig. 2 – Risk of bias summary for included RCT studies. The plus sign indicates low risk of bias; the circle with question mark indicates unclear risk of bias; the minus sign indicates high risk of bias. Overall, studies with at least one minus are considered high risk of bias, studies with at least one question mark unclear risk of bias, while studies with plus signs only low risk of bias.



13

Fig. 3 – Risk of bias summary for included CCT studies. The plus sign indicates low risk of bias; the circle with question mark indicates unclear risk of bias; the minus sign indicates high risk of bias. Overall, studies with at least one minus are considered high risk of bias, studies with at least one question mark unclear risk of bias, while studies with plus signs only low risk of bias. The first two items are not applicable (default: unclear).

3.8.

Qualitative synthesis of included studies

In order to proceed to the qualitative analysis, the 18 studies were divided into five groups according to the intervention used for acceleration of orthodontic tooth movement. An overview of the set-up and the findings of the included studies is provided in Tables 1 and 2.

3.8.1. Effects of Interventions 3.8.1.1. Corticotomy. This intervention is assessed in seven studies.9,33–38 Three studies investigated the effect of corti-

cotomy perforations on the rate of canine retraction.9,33,36 Two of them are of unclear risk of bias and report a significant increase on the pooled rate of true canine movement by 0.73 mm/month during the first month (Fig. 3).9,33 Another high risk of bias study reported similar findings on the same outcome (mm/month: md = 0.52; 95% CI: 0.29, 0.75).36 However, for longer periods of follow-up, reported data indicate that the acceleration in tooth movement appears to be time dependent and the effect of the corticotomy wears off slowly to reach the control baseline level of tooth movement 4 months after the intervention.33



14


Fig. 4 – Meta-analysis for corticotomy. Random-effects meta-analysis of studies applying the corticotomy intervention. Values express millimetres of canine distal movement per month for an assessment period of one month following the intervention.

Two high risk of bias RCTs investigated the effect of corticotomy on the treatment time required for lower anterior crowding correction.37,38 One of them tested corticotomy versus conventional treatment and found significant reduction in treatment time in the experimental group (weeks: md = 31.5; 95% CI: 54.6, 8.4). No significant difference between groups was evident for bone density and root length, while periodontal probing depth increased by a mean of 0.58 mm from pre- to 6 months post-treatment in the experimental group ( p < 0.05).38 The other study tested the effect of corticotomy with versus without bone grafting and did not find any difference in treatment time (weeks: md = 0.3; 95% CI: 1.0, 0.4).37 In this study, periodontal probing depth decreased by a mean of 0.5 mm from pre- to 6 months post-treatment ( p < 0.05) in both groups. A single unclear risk of bias study investigated the effect of corticotomy on positioning of palatally impacted canines on the dental arch.35 A higher tooth movement rate by 0.30 mm/ month with corticotomy versus the control technique was reported for the period from the start of movement until positioning on the dental arch (md = 0.30; 95% CI: 0.20, 0.39). Finally, a single high risk of bias study tested the time required for surgery and the effect on oral health related quality of life, 3 and 7 days after surgery, between corticotomy using round burs and piezoelectric surgery performed mesially and distally along each tooth root from second molar to second molar.34 Oral health quality of life was negatively affected in the first 3 days by both methods and despite the improvement after one week, it did not reach baseline levels. Lower duration of surgery by 6.1 min with rotary versus piezoelectric surgical technique was reported (md = 6.1; 95% CI: 1.2, 11.0). However, the risk of bias of the study was high and the estimate was relatively imprecise as inferred by the associated 95% confidence interval.

No adverse effects on root integrity, oral hygiene, or clinical periodontal parameters were reported for corticotomy procedures, although they were assessed in a single unclear33 and two high risk of bias studies.37,38

3.8.1.2. Low-intensity laser. This intervention is assessed in eight studies.13,26–32 A single unclear risk of bias study evaluated the effect of low-intensity laser on the overall treatment duration of non-extraction Class I cases with mild to moderate crowding.26 The entire treatment duration was significantly reduced by 167 days with the application of lowintensity laser (md = 167; 95% CI: 236, 98). However, this study carries some risk of bias as pre-treatment comparability between tested groups was not addressed adequately. Most of the studies using low-intensity laser irradiation assessed the effect on the rate of canine retraction (or lateral incisor in one case), after 1st premolar extractions.13,27–31 A single unclear risk of bias study also tested the effect on 1st premolar retraction, after 2nd premolar extraction.32 The vast majority of studies reported a positive effect of laser irradiation on the rate of canine movement (33–99%), for an overall follow up period ranging from 35 days to the time needed for complete space closure. Anchorage loss was also included in these rates. These studies were characterized by varying degree of bias (one low, three unclear, and two high risk of bias). Interestingly, a single low risk of bias study did not find a significant difference between the laser and control groups.29 This contradictory finding can be attributed to the different laser application protocol implemented in the last trial. Specifically, they applied laser irradiation on the 1st, 2nd, and 3rd day after initiation of retraction and repeated the 3day application protocol after 1, 2, and 3 months. This frequency of laser exposure and time lapse between serial laser applications is quite low compared to all other studies.



15


Table 3 – Summary of findings table according to the GRADE guidelines for the two studies on corticotomy that were used for quantitative synthesis. Corticotomy compared to conventional retraction for canine retraction Patient or population: patients with canine retraction Settings: split mouth RCT Intervention: corticotomy Comparison: conventional retraction Outcomes

Space closure mm Follow-up: 1 month

Pain follow-up: 1 month

Other adverse effects Follow-up: 4 months

Weighted mean difference (95% CI) between corticotomy vs. conventional retraction

Relative effect (95% CI)

No of participants (studies)

Quality of the evidence (GRADE)

23 (2 split mouth studies)

lowa,b

The mean canine retraction in the intervention groups was 0.73 higher (0.28–1.19 higher) Not estimable

Not estimable

10 (1 split mouth study)

See comment

Not estimable

Not estimable

13 (1 split mouth study)

See comment

Comments

No significant difference in pain and discomfort 1, 7, and 28 days after retraction No significant difference in measurements of plaque index, probing depth, attachment loss, and gingival recession

CI: Confidence interval. GRADE Working Group grades of evidence Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. a Unclear randomization and blinding of participants and personnel. b Wide confidence interval.

Fig. 5 – Meta-analysis for low-intensity laser. Random effects meta-analysis of two split mouth RCT studies applying lowintensity laser therapy intervention. Values express millimetres of canine distal movement per month (molar anchorage loss also included), during an assessment period of 3–4.5 months. Please cite this article in press as: Gkantidis N, et al. Effectiveness of non-conventional methods for accelerated orthodontic tooth movement: A systematic review and meta-analysis. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.07.013


16


Table 4 – Summary of findings table according to the GRADE guidelines for the two studies on low-intensity laser that were used for quantitative synthesis. Low-intensity laser compared to conventional retraction for extraction space closure Patient or population: patients with extraction space closure Settings: split mouth RCT Intervention: low-intensity laser Comparison: conventional retraction Outcomes

Weighted mean Relative effect difference (95% CI) (95% CI) between low intensity laser vs. conventional retraction

Extraction space closure mm/month Follow-up: 3–4.5 months

The mean space closure in the intervention groups was 0.42 higher (0.26–0.57 higher) Not estimable

Not estimable

10 (1 split mouth See comment study)

Not estimable

Not estimable

20 (1 split mouth See comment studies)

Other adverse effects Pain

No. of participants (studies)

Quality of the evidence (GRADE)

Comments

30 (2 split mouth moderatea studies)

No significant difference in root resorption or alveolar bone height Pain intensity was significantly lower in the lased group on day 3 and day 30 after start of canine retraction

CI: confidence interval. GRADE Working Group grades of evidence. Moderate quality: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. a Unclear randomization, allocation concealment, and detection bias in one out of two studies.

Furthermore, the mean rate of canine movement reported in the study was the smallest compared to all other studies (0.41 mm/month), and excluded from measurement of retraction any anchorage loss. Adverse effects were tested in two unclear risk of bias studies.30,32 No significant adverse effects, such as root resorption or worsening of clinical and radiographic periodontal parameters, were evident for this intervention.

3.8.1.3. Photobiomodulation. The evidence on this method is very limited. A single high risk of bias study reported higher tooth movement rate during levelling and alignment of anterior teeth by 2.52 mm/month compared to conventional treatment (md = 2.52; 95% CI: 0.20, 4.84).40 However, the design of this study was poor, lacking appropriate and complete reporting. Potential adverse effects were not investigated in this study. 3.8.1.4. Pulsed electromagnetic fields. The evidence regarding the effect of pulsed electromagnetic fields on tooth movement is very limited. A single high risk of bias study investigated canine retraction until completion of space closure.15 This study suffers from poor reporting, and overall was rated as carrying a high risk of bias. A higher tooth movement rate by 0.3 mm/month with pulsed electromagnetic fields versus conventional retraction was reported (md = 0.30; 95% CI: 0.18, 0.42). Potential adverse effects were not investigated in this study. 3.8.1.5. Interseptal bone reduction. The evidence regarding this intervention is limited. A single unclear risk of bias RCT

tested the effect of interseptal bone reduction on the rate of true maxillary canine retraction in 1st premolar extraction space.39 This study reported an increased canine retraction rate by 0.7 mm/month with interseptal bone reduction versus conventional retraction, during a 3-month observation period (md = 0.70; 95% CI: 0.12, 1.28). Potential adverse effects were not investigated in this study.

4.

Discussion

Reduction of orthodontic treatment time by means of accelerated tooth movement has attracted the interest of the orthodontic community in the recent years. Almost 80% of the included studies investigating techniques for accelerated orthodontic tooth movement were published in the last 4 years, clearly showing an increased interest on the topic. In the past, attempts to accelerate the rate of tooth movement have involved the addition of specific molecules, such as PgE1, which had been found to be associated with inflammation and bone healing.42–44 However, local application of such molecules on humans did not gain much popularity.45 A possible explanation might be its association with increased risk of root resorption and increased pain levels.42,46 Pharmacological approaches to accelerate orthodontic tooth movement were excluded from our analysis since recent studies have shown that these approaches are currently far from clinical application in everyday practice due to applicability, effectiveness, general health, and safetyrelated issues.17,45



17

Fig. 6 – Sensitivity meta-analysis. Random effects sensitivity meta-analysis of studies applying low-intensity laser therapy intervention, adding the study by Limpanichkul et al. (upper) and the study by Youssef et al. (lower). Values express millimetres of canine distal movement per month (molar anchorage loss included in all studies except Limpanichkul et al.), during an assessment period of 3–4.5 months.

Our literature search also revealed eight studies that used distraction osteogenesis devices for canine retraction. This method could be effective in accelerating canine retraction, but it is quite invasive and requires additional procedures and custom-made devices to be applied during regular orthodontic treatment.47,48 Of the eight such studies identified by the search seven were uncontrolled or did not compare different methods, while one compared two surgical techniques applied prior to distraction.49 Those studies were excluded from this systematic review because they did not satisfy the inclusion criteria.

Regarding the investigated interventions, the effects of photobiomodulation or pulsed electromagnetic fields on the rate of tooth movement were examined on single high risk of bias studies. Photobiomodulation was reported to increase the rate of tooth alignment,40 while the application of pulsed electromagnetic fields was reported to increase the rate of canine retraction.15 The clinical importance of the latter relative to total treatment time is questionable. Interseptal bone reduction was also tested by one unclear risk of bias study, which reported increase in the rate of extraction space closure.39 This method seems promising since no flap is



18


required and thus the risks for periodontal adverse effects are minimized. However, other associated adverse effects, such as pain or swelling, should be investigated, as well as the influence of this intervention in the reduction of total treatment time. Corticotomy assisted acceleration of orthodontic tooth movement has been investigated in seven included studies, at varying level of risk of bias.9,33–38 Corticotomy was reported to accelerate the rate of canine tooth movement significantly during the first month after the application of the intervention. However, the effectiveness of this intervention is questionable over time, since a sharp decline of the tooth movement rate is apparent after the second month of observation.33 This transient nature of the intervention might be overcome if a second surgery was to be performed. No studies were found to assess this treatment strategy. However, this procedure would be associated with higher costs and further discomfort and morbidity for the patient. The intervention is reported to have a negative impact on the oral health quality of life, with partial recovery after 7 days.34 Flapless methods could possibly and partly overcome these limitations.9 A larger number of studies investigated the effectiveness of low intensity laser, though the risk of bias was also variable in this category. The majority of the studies report a favourable effect on orthodontic treatment by means of either reduced treatment duration (30% reduction of overall treatment duration)26 or increased rate of tooth movement.13,27,28,30–32 No consensus has been reached on the most effective laser application regimens and irradiation doses. Unfortunately, this cannot be investigated at this time due to the heterogeneity of the available studies.

4.1.

Clinical recommendations

On the basis of the qualitative and quantitative analysis of the available evidence the following recommendations could be made.

at present as a routine procedure, though it could be helpful in certain cases.

4.1.2.

4.1.3.

Corticotomy

There is some consistency of results regarding canine retraction and treatment effect seems significant, at least in the first few months after the intervention. The overall quality of evidence supporting this intervention is low. The number of studies is moderate and clinically heterogeneous. This surgical method is more invasive in comparison to the non-surgical interventions, and thus the patients need to be informed about the post-surgical condition and potential risks from surgery. Flapless methods seem quite promising in these terms, but they need further investigation. No important adverse side effects are expected, though the evidence on this cannot be considered adequate. The duration of the accelerating effect is also questionable, as well as the effect in total treatment time. There is generally no need for costly additional equipment, though there is a possibility of additional cost for the patient, depending on the intervention. A particularly suitable case would be that of a patient requiring another necessary surgical procedure, such as periodontal surgery or exposure of an impacted canine. The cost/benefit ratio for the patient and the doctor remains unclear, thus, this method cannot be recommended

Photobiomodulation

The overall quality of evidence supporting this intervention is very low. Small degree of compliance and additional cost for equipment are required. The cost/benefit ratio for the patient and the doctor remains unclear. Thus, the application of this intervention in everyday clinical practice cannot be recommended at present.

4.1.4. 4.1.1.

Low-intensity laser therapy

The treatment effect seems important and the reported results are consistent in general; the overall quality of evidence supporting this intervention is moderate. This type of intervention appears to be less prone to adverse effects. Although adverse effects were tested only in two studies, significant unfavourable outcomes were not reported and are not expected. On the contrary, there is one favourable parallel effect regarding the reduction of orthodontic pain achieved by the use of low-intensity laser, though further research is required in this field.50,51 For the clinician the need for additional equipment should be considered. As frequent application of the low-intensity laser irradiation is probably needed to achieve significant acceleration, more appointments would be required. The ideal laser settings, timing, frequency, and time lapse between serial laser applications remain to be determined. Portable devices have already been developed and if made widely available and affordable they may expand the applicability of this method in orthodontics.52 Thus, the application of this intervention in everyday practice could be suggested in patients that are willing to attend the practice multiple times and at short intervals. At present, the cost/benefit ratio for the patient and the doctor needs further clarification, although current results are promising.

Pulsed electromagnetic fields

The overall quality of evidence supporting this intervention is very low. Compliance and additional cost for equipment are required. The cost/benefit ratio for the patient and the doctor remains unclear. Thus, the application of this intervention on everyday clinical practice cannot be recommended at present.

4.1.5.

Interseptal bone reduction

The overall quality of evidence supporting this intervention is low. This surgical method is more invasive in comparison to the non-surgical interventions, though it does not require any flap. Thus, the patients need to be informed about the postsurgical condition and potential risks. Adverse effects were not tested so far. The effect in total treatment time is also questionable. There is generally no need for costly additional equipment, though there might be an additional cost for the patient. The cost/benefit ratio for the patient and the doctor remains unclear. Although it holds some promise for the future, based on current evidence, the application of this intervention on everyday clinical practice cannot be recommended at present.



4.2.

Limitations

A shortage of large, high quality studies investigating techniques of accelerated orthodontic tooth movement is evident. In most cases, the included studies have a degree of methodological heterogeneity related to participants, interventions and outcomes which makes comparisons challenging. The majority of included studies have a split-mouth design, where the possibility of carry-across effect or contamination or spilling of the effects of one intervention to another cannot be excluded. Most studies evaluate part of the treatment and not the effect on the entire treatment duration and technique-specific aspects of interventions are not investigated. Adverse effects are investigated in a limited number of studies and no attempt to assess interventions in terms of cost–benefit analysis is reported. Moreover, the overall quality of reporting is suboptimal making data extraction processes problematic. Though grey literature was included in the present systematic review, language restrictions might be an additional limitation.

5.

Conclusion

There is moderate evidence on low laser therapy and low evidence on corticotomy regarding their effectiveness in acceleration of orthodontic tooth movement. The evidence on interseptal bone reduction is limited. The evidence on photobiomodulation or pulsed electromagnetic fields is also limited and of very low quality. Overall, the results should be interpreted with caution given the small number, quality, and heterogeneity of the included studies. There is a need for larger, high quality RCTs. Further research is required on the field of accelerated orthodontics with additional attention paid to application protocols, overall treatment duration, adverse effects and cost–benefit analysis, based on the specific characteristics of each method.

Conflict of interest and sources of funding statement The authors declare that they have no conflict of interests. No funding was received by any source.

Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.jdent.2014.07.013.

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Corticotomies and Orthodontic Tooth Movement: A Systematic Review.

Efficacy of piezocision on accelerating orthodontic tooth movement: A systematic review.

Minimally Invasive Techniques to Accelerate the Orthodontic Tooth Movement: A Systematic Review of Animal Studies.

Tooth eruption and orthodontic movement.

Prediction of orthodontic tooth movement.

Mechanical and thermal hypersensitivities associated with orthodontic tooth movement: a behavioral rat model for orthodontic tooth movement-induced pain.

Efficacy of low-level laser therapy for accelerating tooth movement during orthodontic treatment: a systematic review and meta-analysis.

Osteoimmunology in orthodontic tooth movement.

Tooth movement in orthodontic treatment with low-level laser therapy: systematic review imprecisions.

Accelerated orthodontic tooth movement following le fort I osteotomy in a rodent model.

A periodontal ligament driven remodeling algorithm for orthodontic tooth movement.

Three-dimensional analysis of orthodontic tooth movement.

Tooth movement in orthodontic treatment with low-level laser therapy: a systematic review of human and animal studies.

Force-induced increased osteogenesis enables accelerated orthodontic tooth movement in ovariectomized rats.

Adiponectin prevents orthodontic tooth movement in rats.

Influence of uncontrolled diabetes mellitus on periodontal tissues during orthodontic tooth movement: a systematic review of animal studies.

Clinical tooth preparations and associated measuring methods: a systematic review.

Diagnostic markers for hyperemesis gravidarum: a systematic review and metaanalysis.

Are interventions for accelerating orthodontic tooth movement effective?

Effect of low level laser therapy on orthodontic tooth movement: a review article.

Initial orthodontic tooth movement of a multirooted tooth: a 3D study of a rat molar.

Accelerating orthodontic tooth movement using surgical and non-surgical approaches.

Nrf2 activation attenuates both orthodontic tooth movement and relapse.

Accelerated Tooth Movement and Temporary Skeletal Anchorage Devices (TSADs).