Effectiveness of non-conventional methods for [618573]

Effectiveness of non-conventional methods for
accelerated orthodontic tooth movement:
A systematic review and meta-analysis
Nikolaos Gkantidisa,*, Ilias Mistakidisb, Thaleia Kouskouraa,
Nikolaos Pandisa
aDepartment of Orthodontics and Dentofacial Orthopedics, University of Bern, Freiburgstrasse 7, CH-3010 Bern,
Switzerland
bDepartment of Orthodontics, School of Health Sciences, Faculty of Dentistry, Aristotle University of Thessaloniki,
Thessaloniki, Greecej o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9
a r t i c l e i n f o
Article history:
Received 17 April 2014
Received in revised form
23 May 2014
Accepted 15 July 2014
Keywords:
Orthodontics
Accelerated tooth movement
Corticotomy
Low-level laser therapy
Systematic review
Meta-analysisa b s t r a c t
Objectives: To assess the available evidence on the effectiveness of accelerated orthodontic
tooth movement through surgical and non-surgical approaches in orthodontic patients.
Methods: Randomized controlled trials and controlled clinical trials were identified through
electronic and hand searches (last update: March 2014). Orthognathic surgery, distraction
osteogenesis, and pharmacological approaches were excluded. Risk of bias was assessed
using the Cochrane risk of bias tool.
Results: Eighteen trials involving 354 participants were included for qualitative and quantita-
tive synthesis. Eight trials reported on low-intensity laser, one on photobiomodulation, one on
pulsed electromagnetic fields, seven on corticotomy, and one on interseptal bone reduction.
Two studies on corticotomy and two on low-intensity laser, which had low or unclear risk of
bias, were mathematically combined using the random effects model. Higher canine retrac-
tion rate was evident with corticotomy during the first month of therapy (WMD = 0.73; 95% CI:
0.28, 1.19, p < 0.01) and with low-intensity laser (WMD = 0.42 mm/month; 95% CI: 0.26, 0.57,
p < 0.001) in a period longer than 3 months. The quality of evidence supporting the interven-
tions 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 photo-
biomodulation 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: [anonimizat] (N. Gkantidis).Available online at www.sciencedirect.com
ScienceDirect
journal homepage: www.intl.elsevierhealth.com/journals/jden
http://dx.doi.org/10.1016/j.jdent.2014.07.013
0300-5712/# 2014 Elsevier Ltd. All rights reserved.

1. Introduction
Reduced treatment duration is important for care providers
and orthodontic patients. It is also desirable that aesthetic
concerns1and time dependent adverse events such as
discomfort, pain, external apical root resorption, suboptimal
oral hygiene, white spot lesions and dental caries2are 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-extrac-
tion 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.5Under 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 osteoclas-
tic and osteoblastic activity is observed leading to bone
resorption and apposition that results in tooth movement
through modelling–remodelling of the alveolar bone.6Adjunct
to the proper selection of brackets, wires, embiomechanic
systems, force levels, and anchorage systems, an array of
novel techniques has been introduced to accelerate ortho-
dontic 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.7The idea of surgically
accelerated tooth movement although more than a century
old8has only gained momentum and interest during the last
10 years.9,10Theoretically, selective surgical alveolar bone
reduction induces a localized increase in turnover of alveolar
cancellous bone, suggesting a possible mechanism underly-
ing the observed acceleration of tooth movement.11Another
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 move-
ment.12
Non-surgical techniques include low-intensity laser irradi-
ation,7,13resonance vibration,14pulsed electromagnetic
fields,15electrical currents,16and pharmacological
approaches.17Low laser therapy is reported to stimulate
osteoblast and osteoclast cell proliferation, and enhance the
velocity of tooth movement due to accelerated bone remodel-
ling mediated by the RANK/RANKL/OPG system.18Resonance
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 2011.19Thus, a thorough
systematic evaluation of the most recent clinical evidence
related to accelerated orthodontic treatment is missing fromthe literature. The purpose of the present systematic review is
to critically assess and systematically summarize the avail-
able 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.20,21A 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 move-
ment 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 clarifica-
tions.
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.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1301

2. English, German, French, and Italian languages.
The exclusion criteria were:
1. In vitro and animal studies.
2. Case reports/case series.
3. Studies with sample size less than six.
4. 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, pharma-
cological approaches and distraction osteogenesis techniques
were excluded from the study.
2.4. Control
Comparable patients receiving an alternative accelerating
intervention or conventional orthodontic treatment. Compa-
rable patients receiving different accelerating regimens or
application techniques (i.e. different laser irradiation regi-
mens, 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 orthodon-
tic 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 out-
comes.
2.7. 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,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 character-
istics, (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.22The 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 heteroge-
neity 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.23A 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:ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
sd2
1ț sd2
2/C0 2 /C2 r /C2 sd1/C2 sd2q
where sd1and sd2are the standard deviations between quad-
rants, respectively, and r is the correlation coefficient between
quadrants. The correlation coefficient was set at 0.5 for split-
mouth designs and at 0 for parallel designs.24If 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. Sensitivity analysis
Sensitivity analyses were pre-specified to deal with publica-
tion 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 versionj o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1302

13.1TM(STATA Corporation, College Station, USA) using the
‘metan’ command.
2.11. Determination of available evidence supporting
clinical recommendations
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 (assess-
ment 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 inter-
vention. For the meta-analysis findings the GRADE approachwas implemented in order to assess the level of the existing
evidence.25
3. Results
3.1. Literature flow
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.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1303

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.
Study Subject group Main
objectiveStudy
designTreatments tested Sample
description (size,
sex, age)Malocclusion
characteristicsMethod of
allocation/recruitment
procedure usedDetails of the acceleration
protocol
Camacho and
Cujar (2010)26Low-intensity laser
(treatment duration)Effect on
duration of non-
extraction
orthodontic
treatmentProspective
CCTLow-intensity laser
vs. conventional
treatmentExp.: 23 (12F, 11M;
25.3/C62.8 years)
control: 22 (14F, 8M;
25.6/C62.5 years)Skeletal and dental
Class I, crowding
/C205m mConsecutive/
consecutivePhoton 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
Cruz et al.
(2004)13Low-intensity laser
(maxillary canine
retraction)Effect on rate of
space closureRCT (split
mouth)Low-intensity laser
vs. conventional
treatmentExp. and control: 11
(sex NA; 12–
18 years)Crowding or
bimaxillary protrusionRandom/unclear, based
on specific criteriaGa-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
Limpanichkul
et al. (2006)29Low-intensity laser
(maxillary canine
retraction)Effect on rate of
canine
retractionRCT (split
mouth)Low-intensity laser
vs. conventional
treatmentExp. and control: 12
(8F, 4M;
20.11/C63.4 years)Unclear Random/unclear, based
on specific criteriaGa-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
Youssef et al.
(2008)31Low-intensity laser
(maxillary and
mandibular canine
retraction)Effect on rate of
space closureProspective
CCT (split
mouth)Low-intensity laser
vs. conventional
treatmentExp. and control: 15
(sex NA; 14–
23 years)Crowding or
bimaxillary protrusionBy side (left control,
right exp.)/unclear,
based on specific
criteriaGa-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
Sousa et al.
(2011)30Low-intensity laser
(maxillary and/or
mandibular canine
retraction)Effect on rate of
space closureRCT (split
mouth)Low-intensity laser
vs. conventional
treatmentExp. and control: 10
(6F, 4M; 10.5–
20.2 years)Crowding or
bimaxillary protrusionRandom/unclear, based
on specific criteriaAs-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
Doshi-Mehta
et al. (2012)27Low-intensity laser
(maxillary canine
retraction)Effect on rate of
space closureRCT (split
mouth)Low-intensity laser
vs. conventional
treatmentExp. and control: 20
(12F, 8M; 12–
23 years)Unclear Random/unclear, based
on specific criteriaGa-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
Genc et al. (2013)28Low-intensity laser
(maxillary lateral
incisor retraction)Effect on rate of
retractionProspective
CCT (split
mouth)Low-intensity laser
vs. conventional
treatmentExp. and control: 20
(14F, 6M;
17.8/C64.2 years)Convex profile or
crowdingBy side (left control,
right experimental)/
unclear, based on
specific criteriaGa-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
Dominguez
et al. (2013)32Low-intensity laser
(maxillary 1st
premolar retraction)Effect on rate of
space closureProspective
CCT (split
mouth)Low-intensity laser
vs. conventional
treatmentExp. and control: 10
(5F, 5M;
13.7/C61.3 years)Lack of space in the
upper archBy side (left control,
right experimental)/
Consecutive, based on
specific criteriaDiode 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 7j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1304

Table 1 ( Continued )
Study Subject group Main
objectiveStudy
designTreatments tested Sample
description (size,
sex, age)Malocclusion
characteristicsMethod of
allocation/recruitment
procedure usedDetails of the acceleration
protocol
Kau et al. (2013)40Photobiomodulation
(levelling and
alignment in the
maxilla and/or the
mandible)Effect on time
needed for
alignmentProspective
CCTPhotobiomodulation
vs. conventional
treatmentn: 90 (exp: 73,
control:17) (62F,
28M; 18 /C67 years)Class I with Little’s
irregularity
index>2m mUnclear/consecutive 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
Showkatbakhsh
et al. (2010)15Pulsed
electromagnetic fields
(maxillary canine
retraction)Effect on
amount of space
closureRCT (split
mouth)Pulsed
electromagnetic fields
vs. conventional
treatmentExp. and control: 10
(5F, 5M;
23/C63.3 years)5 Class I and 5 Class II
div.1 patients with
symmetrical crowdingRandom/unclear, based
on specific criteriaAn 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
Aboul-Ela et al.
(2011)33Corticotomy
perforations
(maxillary canine
retraction)Effect on rate of
canine
retractionRCT (split
mouth)Corticotomy vs.
conventional
treatmentExp. and control: 13
(8F, 5M; mean
19 years)Class II div. 1 with
increased overjetRandom/unclear, based
on specific criteriaScattered 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
Alikhani et al.
(2013)9Corticotomy
perforations
(maxillary canine
retraction)Effect on rate of
canine
retractionRCT (and
split mouth
in exp.
group)Corticotomy vs.
conventional
treatmentExp.: 10 (5F, 5M;
mean 26.8 years)
control: 10 (7F, 3M;
mean 24.7 years)Class II div. 1 with
overjet /C2010 mmRandom/unclear, based
on specific criteriaThree 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
Abed and
Al-Bustani (2013)36Corticotomy
perforations
(maxillary canine
retraction)Effect on rate of
canine
retractionProspective
CCT (split
mouth)Corticotomy vs.
conventional
treatmentExp. and control: 12
(8F, 4M; 17–28 years)Unclear By the size of space
(experimental on the
largest space)/unclear3–4 corticotomy perforations
performed mesially and distally
to the canine, with a 1.5 mm
round bur, spaced 2 mm apart
Fischer (2007)35Corticotomy
(positioning of
palatally impacted
canines)Effect on time
needed for
positioning of
palatally
impacted
canines on
dental archRCT (split
mouth)Corticotomy vs.
conventional
treatmentExp. and control: 6
(4F, 2M; 11.1–
12.9 years)Bilateral palatally
impacted caninesRandom/consecutive 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
Shoreibah et al.
(2012a)38Corticotomy (lower
anterior crowding
correction)Effect on time
needed for
crowding
correction,
periodontal
parameters, root
length, and bone
densityRCT Corticotomy vs.
conventional
treatmentExp.: 10, control: 10
(17F, 3M; 18.4–
25.6 years)Lower anterior
crowding 3–5 mm,
skeletal Class IRandom/unclear, based
on specific criteriaVertical 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
teethj o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1305

Table 1 ( Continued )
Study Subject group Main
objectiveStudy
designTreatments tested Sample
description (size,
sex, age)Malocclusion
characteristicsMethod of
allocation/recruitment
procedure usedDetails of the acceleration
protocol
Shoreibah et al.
(2012b)37Corticotomy (lower
anterior crowding
correction)Effect of bone
grafting on time
needed for
crowding
correction,
periodontal
parameters, root
length, and bone
densityRCT Corticotomy with vs.
without bone graftingExp.: 10, control: 10
(16F, 4M; mean age
24.5 years)Lower anterior
crowding 3–5 mm,
skeletal Class IRandom/unclear, based
on specific criteriaVertical 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
Cassetta et al.
(2012)34Corticotomy 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
osteotomyRCT Piezoelectric surgery
vs. conventional
rotary osteotomyExp.: 12 (6 piezo, 6
rotatory) (8F, 4M;
13–17 years)Bilateral Class I molar
occlusion with a
moderate-severe
crowding or/and
unilateral crossbiteRandom/based on
specific criteriaPiezoelectric 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
Leethanakul
et al., 201439Interseptal bone
reduction (maxillary
canine retraction)Effect on rate of
canine
retractionRCT
(split
mouth)Interseptal bone
reduction vs.
conventional
treatmentExp. and control: 18
(18F,
21.9/C64.7 years)Unclear Random/unclear, based
on specific criteriaThe 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
Exp.: experimental group.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1306

3.2. Description of studies
From the 18 included studies, eight tested the effect of
application of low intensity laser on orthodontic tooth
movement13,26–32and seven studies evaluated corticotomy-
assisted orthodontic treatment.9,33–38The effects of intersep-
tal bone reduction,39pulsed electromagnetic fields15and
photobiomodulation40were 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,27,29five as un-
clear,9,30,33,35,39and 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
unclear26,31,32and 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.9,26,27,29–33,35,39From those, two studies evaluating
corticotomy assisted canine retraction rate9,33and four
studies evaluating application of low-intensity laser on rate
of canine retraction27,29–31were considered appropriate for
attempting meta-analysis. Calculation of predictive intervals
was not possible since it requires larger number of low risk of
bias studies.41The results of Camacho and Cujar26could not be
pooled due to different outcome measures (overall duration ofnon-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.39an 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 com-
bined 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 sugges-
tive 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.27,30Both 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. Meta-
analysis 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 meta-
analyses were undertaken to gauge the inclusion of the studies
by Limpanichkul et al.29and Youssef et al.31on 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: /C00.02, 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 meta-
analysis. 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).j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1307

Table 2 – Results of individual studies, overall quality assessment, and synthesis of results.
Study Subject group Definition of pre-specified
main outcomeSummary outcome data Additional outcomes Quality
assessmenta
Camacho and
Cujar (2010)26Low-intensity laser
(treatment duration)Time required to complete
orthodontic treatmentTreatment duration
exp.: 398 /C688 days,
control: 565 /C6130 days,
p<0.001NA Unclear risk
Cruz et al.
(2004)13Low-intensity laser
(maxillary canine
retraction)Amount of space closure
obtained after 2 monthsSpace closure in 2 months
exp.: 4.4 /C60.3 mm
control: 3.3 /C60.2 mm,
p<0.001NA High risk
Limpanichkul
et al. (2006)29Low-intensity laser
(maxillary canine
retraction)Amount of retraction
obtained after 3 monthsCanine retraction at 3
months
exp.: 1.3 /C60.2 mm
control: 1.2 /C60.2 mm,
p= 0.57NA Low risk
Youssef et al.
(2008)31Low-intensity laser
(maxillary and
mandibular canine
retraction)Rate of space closure to
complete closure of the
extraction spaceSpace closure rate up to
complete closure (mm/
month)
exp.: 2.0 /C60.1,
control: 1.0: /C60.1,p<0.001Pain intensity was
significantly lower in the
lased group than in the
control group throughout the
retraction periodUnclear risk
Sousa et al.
(2011)30Low-intensity laser
(maxillary and/or
mandibular canine
retraction)Amount of space closure
obtained after 3 monthsSpace closure at 3 months
exp.: 3.09 /C61.06 mm,
control: 1.60 /C60.63 mm,
p<0.001No statistically significant
difference in root resorption
or alveolar bone heightUnclear risk
Doshi-Mehta
et al. (2012)27Low-intensity laser
(maxillary canine
retraction)Space closure distance and
rate upon the completion of
retraction on experimental
quadrant ( /C254.5 months)Space closure at the end of
retraction on exp. side
exp.: 5.5 /C61.0 mm,
control: 4.0 /C61.0 mm,
p<0.001
Rate of retraction (mm/
month)
exp.: 1.1 /C60.2,
control: 0.8 /C60.2,p<0.01The 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 retractionLow risk
Genc et al.
(2013)28Low-intensity laser
(maxillary lateral
incisor retraction)Amount of retraction
obtained after 35 daysLateral incisor retraction
after 35 days (approximation
based on figure)
exp.: 2.4 mm,
control: 1.7 mm, p<0.001NA High risk
Dominguez
et al. (2013)32Low-intensity laser
(maxillary 1st premolar
retraction)Amount of space closure
obtained after 45 daysSpace closure after 45 days
exp.: 3.7 /C61.1 mm,
control: 2.7 /C60.9 mm,
p<0.05No 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 groupUnclear riskj o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1308

Table 2 ( Continued )
Study Subject group Definition of pre-specified
main outcomeSummary outcome data Additional outcomes Quality
assessmenta
Kau et al.
(2013)40Photobiomodulation
(levelling and
alignment in the
maxilla and/or the
mandible)Rate of alignment until
irregularity was /C201m mRate of alignment (mm/
week)
exp.: 1.1 /C61.0,
control: 0.5 /C60.4,p<0.001NA High risk
Showkatbakhsh
et al. (2010)15Pulsed electromagnetic
fields (maxillary canine
retraction)Amount of space closure
until Class I canine
relationship in either of the
caninesSpace closure until canine
Class I
exp.: 5.0 /C61.3 mm,
control: 3.5 /C61.6 mm,
p<0.001NA High risk
Aboul-Ela
et al. (2011)33Corticotomy
perforations (maxillary
canine retraction)Rate of retraction after 4
monthsCanine 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/C200.01 for total observation
timeNo statistically significant
difference in plaque index,
probing depth, attachment
level, and gingival recession.
Gingival index was slightly
higher on the operated sideUnclear risk
Alikhani
et al. (2013)9Corticotomy
perforations (maxillary
canine retraction)Rate of retraction after 1
monthCanine retraction after 28
days:
exp.: 1.1 /C60.2 mm
control: 0.5 /C60.2 mm,
p<0.05No 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. groupUnclear risk
Abed and
Al-Bustani
(2013)36Corticotomy
perforations (maxillary
canine retraction)Rate of retraction after 1
monthCanine retraction after 1
month:
exp.: 1.74 /C60.47 mm
control: 1.22 /C60.40 mm,
p<0.005No difference in anchorage
loss between surgical and
non-surgical sides. No
difference on gingival sulcus
depth and tooth vitality pre-
and post-surgeryHigh risk
Fischer (2007)35Corticotomy
(positioning of
palatally impacted
canines)Canine movement rate until
the tips of both canine
crowns were properly
positionedCanine movement rate (mm/
week)
exp.: 0.26 /C60.04
control: 0.19 /C60.01, p<0.001NA Unclear riskj o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1309

Table 2 ( Continued )
Study Subject group Definition of pre-specified
main outcomeSummary outcome data Additional outcomes Quality
assessmenta
Shoreibah
et al. (2012a)38Corticotomy (lower
anterior crowding
correction)Time needed for lower
anterior crowding correctionMean treatment duration
exp.: 17.5 /C62.8 weeks
control: 49 /C612.3 weeks,
p<0.05No 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 6-
months post-treatment in a
similar way for both groupsHigh risk
Shoreibah
et al. (2012b)37Corticotomy (lower
anterior crowding
correction)Time needed for lower
anterior crowding correctionMean treatment duration
exp. (+bone graft): 16.7 (14–
20) weeks
control ( /C0bone graft): 17 (14–
20) weeks, nsProbing depth decreased
significantly from pre- to 6-
months post-treatment by
approximately 0.5 mm in
both groups. Bone density
decreased in the control
group by 17.6 /C65.8% from
pre- to 6-months post-
treatment, while it increased
by 25.9 /C615.6% in the bone
graft group. Root length
decreased by approximately
0.5 mm from pre- to 6-
months post-treatment in
both groupsHigh risk
Cassetta
et al. (2012)34Corticotomy using
piezo vs. round burs
(surgery duration and
quality of life)Time required for
intervention. Effect on the
OHRQoL 3 and 7 days after
surgeryMean 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= 0.35NA High risk
Leethanakul
et al. (2014)39Interseptal bone
reduction (maxillary
canine retraction)Rate of retraction after 3
monthsCanine retraction rate (mm/
month)
1st month
exp.: 1.6 /C61.1, control:
0.9/C60.3,p/C200.005
2nd month
exp.: 2.3 /C61.1, control:
1.2/C60.5,p/C200.005
3rd month
exp.: 1.6 /C60.8, control:
1.3/C60.7,p/C200.01No 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 movementUnclear risk
aDetails on risk of bias assessment can be found in Fig. 2 for RCTs and Fig. 3 for CCTs.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1310

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.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1311

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.9,33–38Three studies investigated the effect of corti-cotomy perforations on the rate of canine retraction.9,33,36Two
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).9,33Another
high risk of bias study reported similar findings on the same
outcome (mm/month: md = 0.52; 95% CI: 0.29, 0.75).36Howev-
er, 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
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).j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1312

Two high risk of bias RCTs investigated the effect of
corticotomy on the treatment time required for lower anterior
crowding correction.37,38One of them tested corticotomy
versus conventional treatment and found significant reduc-
tion in treatment time in the experimental group (weeks:
md = /C031.5; 95% CI: /C054.6, /C08.4). 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).38The other study tested the
effect of corticotomy with versus without bone grafting and
did not find any difference in treatment time (weeks:
md = /C00.3; 95% CI: /C01.0, 0.4).37In 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.35A 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 mesi-
ally and distally along each tooth root from second molar to
second molar.34Oral 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 proce-
dures, although they were assessed in a single unclear33and
two high risk of bias studies.37,38
3.8.1.2. Low-intensity laser. This intervention is assessed in
eight studies.13,26–32A 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.26The entire treatment duration was
significantly reduced by 167 days with the application of low-
intensity laser (md = /C0167; 95% CI: /C0236, /C098). 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.13,27–31A
single unclear risk of bias study also tested the effect on 1st
premolar retraction, after 2nd premolar extraction.32The 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.29This 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 3-
day 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.
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.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1313

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 Weighted
mean
difference (95%
CI) between
corticotomy vs.
conventional
retractionRelative effect
(95% CI)No of participants
(studies)Quality of the
evidence (GRADE)Comments
Space closure mm
Follow-up: 1 monthThe mean canine
retraction in the
intervention groups
was 0.73 higher
(0.28–1.19 higher)23 (2 split mouth
studies)/C8/C8/C9/C9 lowa,b
Pain follow-up:
1 monthNot estimable Not estimable 10 (1 split mouth
study)See comment No significant difference
in pain and discomfort
1, 7, and 28 days after
retraction
Other adverse effects
Follow-up: 4 monthsNot estimable Not estimable 13 (1 split mouth
study)See comment 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.
aUnclear randomization and blinding of participants and personnel.
bWide confidence interval.
Fig. 5 – Meta-analysis for low-intensity laser. Random effects meta-analysis of two split mouth RCT studies applying low-
intensity 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.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1314

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 retrac-
tion any anchorage loss.
Adverse effects were tested in two unclear risk of bias
studies.30,32No significant adverse effects, such as root
resorption or worsening of clinical and radiographic peri-
odontal 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).40However, 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.15This
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 RCTtested the effect of interseptal bone reduction on the rate of
true maxillary canine retraction in 1st premolar extraction
space.39This 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 accel-
erated 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.42–44However, local applica-
tion of such molecules on humans did not gain much
popularity.45A possible explanation might be its association
with increased risk of root resorption and increased pain
levels.42,46Pharmacological approaches to accelerate ortho-
dontic 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 safety-
related issues.17,45Table 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
difference (95% CI)
between low intensity
laser vs. conventional
retractionRelative effect
(95% CI)No. of
participants
(studies)Quality of
the evidence
(GRADE)Comments
Extraction space
closure mm/month
Follow-up: 3–4.5
monthsThe mean space
closure in the
intervention groups
was 0.42 higher
(0.26–0.57 higher)30 (2 split mouth
studies)/C8/C8/C8/C9 moderatea
Other adverse
effectsNot estimable Not estimable 10 (1 split mouth
study)See comment No significant difference
in root resorption or
alveolar bone height
Pain Not estimable Not estimable 20 (1 split mouth
studies)See comment 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.
aUnclear randomization, allocation concealment, and detection bias in one out of two studies.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1315

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.47,48Of 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.49Those 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,40while the application of pulsed
electromagnetic fields was reported to increase the rate of
canine retraction.15The 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.39This method seems promising since no flap is
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.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1316

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.9,33–38Corticotomy 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.33This
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.34Flapless 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)26or 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 heteroge-
neity 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.
4.1.1. 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 acceler-
ating 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 recommendedat present as a routine procedure, though it could be helpful in
certain cases.
4.1.2. 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 ortho-
dontic pain achieved by the use of low-intensity laser, though
further research is required in this field.50,51For 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.
4.1.3. 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. 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 post-
surgical 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.j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 1 3 0 0 – 1 3 1 9 1317

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, inter-
ventions and outcomes which makes comparisons challeng-
ing. 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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