Pulp Revascularization or Apexification for the Treatment of Immature Necrotic Permanent Teeth: Systematic Review and Meta-Analysis

Abstract

This systematic review and meta-analysis assessed clinical, radiographic and functional retention outcomes in immature necrotic permanent teeth treated either with pulp revascularization or apexification after a minimum of three months to determine which one provides the best results. The literature was screened via PubMed/MEDLINE and Embase databases up to June 2017 to select observational studies that compared pulp revascularization and apexification treatments assessing clinical, radiographic and functional retention outcomes. Two reviewers independently performed screening and evaluation of articles. A total of 231 articles were retrieved from databases, wherein only four articles were selected for full-text analyses. After exclusion criteria, three studies remained in quantitative and qualitative analyses. Pooled-effect estimates were obtained comparing clinical and radiographic outcomes (‘overall outcome’) and functional retention rates between apexification and pulp revascularization treatment. The meta-analysis comparing apexification vs. revascularization for ‘overall outcome’ (Z=0.113, p=0.910, RR=1.009, 95%CI:0.869–1.171) and functional retention rates (Z=1.438, p=0.150, RR=1.069, 95%CI:0.976–1.172) showed no statistically significant differences between the treatments. All studies were classified as high quality. The current literature regarding the clinical, radiographic and functional retention outcomes in immature necrotic permanent teeth treated either with pulp revascularization or apexification is limited. Based on our meta-analysis, the results do not favor one treatment modality over the other.

Full text

Pulp Revascularization or Apexication for the Treatment of Immature Necrotic Permanent Teeth
The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019 doi 10.17796/1053-4625-43.5.1 1
Pulp Revascularization or Apexication for the Treatment of
Immature Necrotic Permanent Teeth: Systematic Review and Meta-
Analysis
Gabriel Ferreira Nicoloso*/ Gabriela Maltz Goldenfum**/Tatiane da Silva Dal Pizzol***/
Roberta Kochenborger Scarparo****/ Francisco Montagner*****/ Jonas de Almeida Rodrigues******/
Luciano Casagrande*******
This systematic review and meta-analysis assessed clinical, radiographic and functional retention outcomes
in immature necrotic permanent teeth treated either with pulp revascularization or apexication after a
minimum of three months to determine which one provides the best results. The literature was screened via
PubMed/MEDLINE and Embase databases up to June 2017 to select observational studies that compared
pulp revascularization and apexication treatments assessing clinical, radiographic and functional retention
outcomes. Two reviewers independently performed screening and evaluation of articles. A total of 231 articles
were retrieved from databases, wherein only four articles were selected for full-text analyses. After exclusion
criteria, three studies remained in quantitative and qualitative analyses. Pooled-eect estimates were
obtained comparing clinical and radiographic outcomes (‘overall outcome’) and functional retention rates
between apexication and pulp revascularization treatment. The meta-analysis comparing apexication vs.
revascularization for ‘overall outcome’ (Z=0.113, p=0.910, RR=1.009, 95%CI:0.869-1.171) and functional
retention rates (Z=1.438, p=0.150, RR=1.069, 95%CI:0.976-1.172) showed no statistically signicant
dierences between the treatments. All studies were classied as high quality. The current literature regarding
the clinical, radiographic and functional retention outcomes in immature necrotic permanent teeth treated
either with pulp revascularization or apexication is limited. Based on our meta-analysis, the results do not
favor one treatment modality over the other.
Keywords: Pulp revascularization, apexication, immature necrotic permanent teeth
From the Federal University of Rio Grande do Sul (UFRGS), Porto Alegre–
RS, Brazil.
Gabriel Ferreira Nicoloso, DDS, MS, PhD, School of Dentistry, Inedi
College - CESUCA, Cachoeirinha, RS, Brazil.
Gabriela Maltz Goldenfum, DDS, MS, School of Dentistry, Post-Graduate
Program in Pediatric Dentistry.
Tatiane da Silva Dal Pizzol, MS, PhD, Faculty of Medicine, Post-Graduate
Program in Epidemiology.
Roberta Kochenborger Scarparo, DDS, MS, PhD, Faculty of Dentistry,
Post-Graduate Program in Endodontics,
Francisco Montagner, DDS, MS, PhD, Faculty of Dentistry, Post-Graduate
Program in Endodontics.
Jonas de Almeida Rodrigues DDS, MS, PhD, School of Dentistry, Post-Grad-
uate Program in Pediatric Dentistry.
Luciano Casagrande, DDS, MS, PhD, School of Dentistry, Post-Graduate
Program in Pediatric Dentistry.
Send all correspondence to:
Luciano Casagrande
Ramiro Barcelos 2492, Bom Fim, Porto Alegre, RS 90.035-003, Brazil
Phone: 0XX(51) 3308 5493
E-mail: luciano.casagrande@ufrgs.br; luciano.casagrande@gmail.com
INTRODUCTION
Pulp necrosis in children and adolescents, mainly due to
trauma or caries, may arrest permanent tooth root devel-
opment, resulting in thin dentinal walls, wide-open apexes
and inadequate crown-root ratio1,2. These features may hamper the
endodontic treatment, and its protocol for cleaning, shaping and
lling root canals must be modied3,4.
Traditionally, apexication has been employed as a treatment
option for immature necrotic permanent teeth. Calcium hydroxide
(CH) apexication requires long-term intracanal medication aiming
to stimulate the formation of an apical calcied barrier, which may
be time-consuming and enhance the incidence of root fracture. On
the other hand, placement of mineral trioxide aggregate (MTA)
apical plugs reduces the number of treatment sessions because there
is a possibility to perform immediate obturation, and thus, may
provide some advantages and more successful outcomes over CH
apexication. However, neither CH nor MTA apexication promote
additional root development, leaving fragile dentinal walls3,5 that
may eventually lead to tooth fracture over time. Is such conditions,

Pulp Revascularization or Apexication for the Treatment of Immature Necrotic Permanent Teeth
2 doi 10.17796/1053-4625-43.5.1 The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019
tooth extraction5-7 is likely to be indicated aecting occlusal func-
tion, esthetic and self-esteem in young patients.
Other endodontic treatments, named as “regenerative endodon-
tics”, “pulp revascularization” or “revitalization” have been
suggested. These techniques oer the possibility of additional
root development, which is aimed to reduce the incidence of root
fracture over time. The European Society of Endodontology (ESE)
statement indicates that “pulp revitalization” is an alternative to
apexication in properly selected cases, since a growing body of
evidence shows clinical feasibility of this approach8. According
to the American Association of Endodontics (AAE)9, “pulp revas-
cularization” is the rst treatment option for immature necrotic
permanent teeth that has incomplete root development (length) and
wide-open apex. Pulp revascularization treatment consists basically
of root canal chemical disinfection with irrigating solution and
intracanal medication followed by blood clot (BC) induction, MTA
coronal seal and placement of crown restoration10. BC induction is
the most frequently technique employed, however, there are other
pulp revascularization techniques, e.g., platelet rich-plasma (PRP)
and platelet rich-brin (PRF), despite the results of these techniques
showing similar outcomes to BC11.
Regardless of the treatment performed, the endodontic success
of these immature teeth should be assessed based on the remission
of clinical signs and symptoms and resolution of periapical radiolu-
cency11. Despite this formerly assessed outcomes, functional tooth
retention is an outcome important to be considered, specically in
young patients, because before the age of eighteen, they may not
choose to have dental implants if needed, as a proper maxillary and
mandibular bone development is mandatory.
Recently, a systematic review of randomized clinical trials11
reported that MTA apexication is likely to result in higher clinical
and radiographic success rates than other endodontic treatments in
immature necrotic permanent teeth. However, most of the included
articles were considered of moderate and high bias risk, and did
not evaluated the functional retention of treated teeth. In fact,
randomized clinical trials may provide strong evidence on decision
making regarding dierent treatments, but these controlled settings
are likely to hamper extrapolation of the studies’ results to daily
clinical practice12. Hence, a systematic review of well-constructed
observational studies is also important to be conduct because there
is a tendency that the studies’ results to be closer to practitioners’
clinics reality.
To date, there is no systematic review and meta-analysis that
screened observational studies regarding pulp revascularization
and apexication treatment. Therefore, the aim of this systematic
review and meta-analysis was to assess the clinical, radiographic
and functional retention outcomes in immature necrotic permanent
teeth treated either with pulp revascularization or apexication after
a minimum of three months to determine which one provides the
best results.
METHODS
This systematic review was reported according to the MOOSE
(Meta-Analysis of Observational Studies in Epidemiology) study
guideline13. It was registered at the International Prospective Register
of Systematic Review (PROSPERO) database (CRD42017070058).
PICO/PECO research question
The following research question was developed according to
the recognized Patient, Intervention/Exposition, Comparison and
Outcome (PICO/PECO) format: “Are pulp revascularization treat-
ments more eective than apexication ones regarding clinical,
radiographic and functional retention outcomes to manage immature
necrotic permanent teeth?”. Population were patients with immature
necrotic permanent teeth; Intervention/Exposition was pulp revas-
cularization treatment; Comparison was apexication treatment;
and Outcomes were clinical, radiographic and functional retention.
Search strategy
A comprehensive literature search was conducted on MEDLINE
via PubMed database up to June 16th, 2017. The following search
strategy were used to explore MEDLINE via PubMed database:
(((((((((((immature teeth) OR immature tooth) OR immature denti-
tion) OR immature permanent teeth) OR immature permanent
tooth) OR immature permanent dentition) OR young permanent
teeth) OR young permanent tooth) OR young permanent denti-
tion)) AND ((((((((((((pulp revascularization) OR pulpal regenera-
tion) OR pulp revitalization) OR root canal revascularization) OR
root maturation) OR regenerative endodontic*) OR regenerative
endodontic therapy) OR regenerative endodontic treatment*) OR
regenerative endodontic procedure*) OR blood clot) OR plate-
let-rich brin) OR platelet-rich plasma)) AND ((((((((((calcied
barrier) OR apical closure) OR root end formation) OR root apex
closure) OR apical plug) OR MTA plug) OR apexication[MeSH
Terms]) OR apexication*) OR mineral trioxide aggregate) OR
calcium hydroxide). Also, a search was conducted on Embase up
to June 16th, 2017. On this database the following search strategy
were used: ‘immature teeth’ OR ‘immature tooth’ OR ‘immature
dentition’ OR ‘immature permanent teeth’ OR ‘immature permanent
tooth’ OR ‘immature permanent dentition’ OR ‘young permanent
teeth’ OR ‘young permanent tooth’ OR ‘young permanent dentition’
AND (‘pulp revascularization’ OR ‘pulpal regeneration’ OR ‘pulp
revitalization’ OR ‘root canal revascularization’ OR ‘root matura-
tion’ OR ‘regenerative endodontic*’ OR ‘regenerative endodontic
therapy’ OR ‘regenerative endodontic treatment*’ OR ‘regenerative
endodontic procedure*’ OR ‘blood clot’/exp OR ‘blood clot’ OR
‘platelet-rich brin’ OR ‘platelet-rich plasma’) AND (‘calcied
barrier’ OR ‘apical closure’ OR ‘root end formation’ OR ‘root apex
closure’ OR ‘apical plug’ OR ‘mta plug’ OR ‘apexication’/de OR
apexication* OR ‘mineral trioxide aggregate’/exp OR ‘calcium
hydroxide’/exp OR ‘calasept’ OR ‘calcium hydroxide’ OR ‘calxyl’
OR ‘hypocal’ OR ‘limewater’ OR ‘pulpdent’. The results of these
two databases searches were cross-checked to locate and eliminate
duplicates.
Eligibility criteria
The inclusion criteria of this systematic review were: (1) Study
design: observational studies (case-control and cohort design);
(2) Participants: patients with immature necrotic permanent teeth;
(3) Intervention: revascularization procedures; (4) Comparison:
apexication procedures; (5) Outcomes: have assessed success by
clinical, radiographic and functional retention outcomes; and (6)
articles published in English.

Pulp Revascularization or Apexication for the Treatment of Immature Necrotic Permanent Teeth
The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019 doi 10.17796/1053-4625-43.5.1 3
The exclusion criteria were: (1) teeth presenting pulpitis and
vital pulp therapy; (2) teeth with previous treatment to necrosis; (3)
follow-up less than three months; (4) did not compare pulp revascu-
larization with apexication; (5) clinical protocol for each proposed
treatment incomplete, e.g., in CH apexication, should have
performed root canal obturation with gutta-percha after the calcied
barrier induction; or, in pulp revascularization cases, should have
performed blood clot induction followed by MTA coronal seal and
placement of crown restoration.
Study selection and data collection
Two reviewers (G.F.N. and G.M.G.) independently screened all
titles and abstracts retrieved by the electronic search. Afterwards,
full-text articles of previous included studies were independently
assessed by the same authors in order to apply previous established
exclusion criteria. Those articles that fullled all criteria were
included in qualitative and quantitative syntheses.
Additionally, all references of included studies were manually
screened for potentially relevant articles. Any possible discrepan-
cies encountered during this process were discussed between the
reviewers, and if disagreement still persisted, the judgment of a third
reviewer (L.C.) was considered decisive.
Data regarding the included studies were independently
extracted by the reviewers (G.F.N. and G.M.G.) based on a previ-
ously dened protocol in a specic form in the Microsoft Oce
Excel 2007 software (Microsoft Corporation, Redmond, WA,
USA). The data extracted included: type of study, year of publica-
tion, country, type of teeth (anterior or posterior teeth), number of
patients and treated teeth, age of patients, etiology and diagnosis of
pulp necrosis, presence of periapical lesion at the beginning, type of
intervention, type of irrigating solution and intracanal medication,
number of successful cases (clinically, radiographically and func-
tional retention), increase in root length and width, calcied barrier
formation, crown discoloration, reasons for failures and follow-up
of observed cases.
Outcome measures
The primary outcomes of interest were clinical, radiographic
and functional retention outcomes of either pulp revascularization or
apexication treatment performed in immature necrotic permanent
teeth. In this case, only remission of periapical radiolucency (either
healing or healed cases) were considered as successful radiographic
outcome. Secondary outcome of interest was assessed based on root
maturation (increase in root length and width during the follow-up)
and formation of calcied barrier, observed in radiographic images.
Clinical and radiographic outcomes were pooled together as
single outcome, and consequently, reported as ‘overall outcome’
(because the authors of the included studies combined them together).
The success or failure of the ‘overall outcome’ was considered in
a dichotomous manner (yes or no), based on the author’s criteria
previously dened in each study. Functional retention outcome was
also assessed in a dichotomous manner, loss or remained.
Quality assessment of the included studies
Two blinded reviewers (G.F.N. and G.M.G.) independently
assessed the methodological quality of included studies according
to Newcastle-Ottawa Scale (NOS) for assessing the quality of
nonrandomized studies in meta-analyses14, adapted for the design of
included studies. It is based on a ‘star system’, ranging from zero to
nine stars, in which a study is judged on three broad perspectives:
selection of study groups (four stars); comparability of groups (two
stars); and ascertainment of either exposure or outcome of interest
(three stars) for case-control or cohort studies, respectively. We
considered the threshold ‘seven stars’ for “high” and “low” quality
studies, i.e., if a study received seven or more stars it was considered
of “high” quality.
Statistical methods for the meta-analysis and assess-
ment of heterogeneity
The meta-analysis was conducted using Comprehensive
Meta-Analysis Software version 3.3 (Biostat, Englewood, NJ) using
random-eect models presented as forest plot with 95% Condence
Interval (CI). Pooled-eect estimates were obtained comparing the
failure rate between groups, and it was reported as risk ratio (RR). A
p-value <0.05 was considered statistically signicant (Z test). Statis-
tical heterogeneity of the treatment eect (experimental endodontic
treatment vs control) among studies was assessed using Cochran’s
Q test, with a threshold p-value of 0.1, and the inconsistency I2 test,
in which values between 25-50% were considered indicative of low
heterogeneity, between 50-75% moderate and greater than 75% of
high heterogeneity.
RESULTS
Study selection
Study selection ow diagram is shown in Figure 1. The liter-
ature search conducted yield 231 articles. After duplicates were
removed (11 coincided from PubMed/MEDLINE and Embase), 220
studies remained. The inclusion criteria were applied upon titles and
abstracts yielding a number of four articles. Afterwards, references
of these articles were manually searched from potential relevant
articles, but none were identied. Then, full text articles were
assessed applying the exclusion criteria. One study15 was excluded
because clinical proposed treatment protocol was incomplete, i.e.,
most of revascularization cases remained with intracanal medication
for outcome evaluation. Therefore, a total of three studies1,2,6 were
included in quantitative and qualitative analyses. Perfect agreement
between reviewer’s study selection was obtained (kappa = 1.0)
Figure 1. Flowchart of study selection.

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4 doi 10.17796/1053-4625-43.5.1 The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019
Study characteristics
Characteristics of each included study are summarized in Table
1. The included studies were retrospective cohorts. Publication
year ranged from 2012 to 2017. Two studies1,2 were carried out in
Thailand and one6 in the United States. Either anterior or posterior
teeth were assessed for outcomes of interest, with or without peri-
apical lesions at the beginning of the study. Trauma was main cause
of endodontic treatment in immature necrotic permanent teeth,
followed by dens invaginatus and caries. Diagnosis of pulp necrosis
and outcome assessment were made by clinical and radiographic
evaluation (combined together) in the included studies. A total of
135 teeth were evaluated with a follow-up (mean) ranging from one
to four years.
All revascularization cases were performed with a rubber dam
isolation. Authors did not state clearly whether CH or MTA apexi-
cation were performed under rubber dam isolation, with the excep-
tion of one study2 that reported all endodontic treatments being
performed under rubber dam isolation. The usual irrigating solu-
tion for revascularization cases was sodium hypochlorite (various
concentrations), followed by EDTA in some cases6, or in all cases2.
Only one study2 stated clearly that 2.5% sodium hypochlorite was
used for MTA apexication. One study1 used triple antibiotic paste
in all revascularization cases; another one6 used triple antibiotic
paste, double antibiotic paste or calcium hydroxide as intracanal
medicament; and Silujjai and Linsuwanont2 used either triple antibi-
otic paste or calcium hydroxide.
Considering ‘overall outcomes’ (clinical and radiographic
outcomes combined), there was no signicant dierence between
pulp revascularization with BC induction and MTA apexication
among the included studies. There was no dierence between CH
apexication and MTA or BC according to Alobaid et al 6, however,
authors included only few cases, which may lead to some bias, and
consequently, should be interpreted with caution. A statistically
signicant dierence was observed according to Jeeruphan et al (1)
favoring BC or MTA when compared to CH apexication. On the
other hand, when functional retention was assessed, only one study
(1) reported inferior rates for CH apexication in comparison to BC
or MTA apexication.
None of the included studies assessed the formation of calcied
barrier as an outcome of interest. Alobaid et al6 was the only study
that reported crown discoloration (crown staining) as an adverse
event of revascularization procedures. They observed that two out
of 19 teeth (10.5%) treated with BC induction presented crown
discoloration. There were no cases of crown discoloration for apexi-
cation techniques6. There was a statistically signicant increase in
root length and width favoring BC cases according to Jeeruphan et
al1 Alobaid et al 6 did not found a statistically signicant dierence
among the treatments, and Silujjai and Linsuwanont2 observed only
a statistically signicant increase in root width favoring BC cases
when compared to MTA apexication.
Regarding the reasons for failure, two studies1,2 reported root or
tooth fracture as the main cause in apexication cases. Two studies2,6
stated that in BC cases, the most common reasons for failure was
reinfection or persistent infection.
Quality assessment of included studies
The results of the quality assessment using the Newcastle-Ot-
tawa Scale (NOS) for verifying the quality of nonrandomized
studies are presented in Table 2. The scores were ‘seven stars’ in
one study6 and ‘eight stars’ in two studies1,2, and therefore, were
considered of high quality. In all studies the patients were reviewed
retrospectively, which may account for some risk of bias in case
selection. Alobaid et al 6 reported that the stage of root development
was dierent between revascularization and apexication cases.
This may have contributed for dierences in quantitative analyses,
such as increase in root width and length. Hence, this study6 was
judged of potentially biased in the ‘comparability domain’, and
thus, received only ‘one star’. Perfect agreement between review-
er’s quality assessment was obtained (kappa = 1.0)
Meta-analysis
The comparisons were performed between apexication (CH
and MTA) and revascularization treatments (BC induction). Two
independent meta-analyses were performed to evaluate whether
apexication or pulp revascularization present better ‘overall
outcomes’ (clinical and radiographic) or functional retention
outcomes. Although Alobaid et al 6 presented CH and MTA as a
‘single’ treatment, the authors stated that the success were 100% for
apexication. Therefore, as the authors reported 12 cases of success,
we preferred to separate the results and present ‘overall outcomes’
and functional retention outcomes as 7 cases of success for CH and
5 cases of success for MTA apexication.
There was no statistically signicant dierence concerning
‘overall outcomes’ (Z=0.113, p=0.910, RR=1.009, 95%CI:0.869-
1.171, I2 = 43%) (Figure 2) and functional retention outcomes
(Z=1.438, p=0.150, RR=1.069, 95%CI:0.976-1.172, I = 0%) (Figure
3) when apexication (CH or MTA) was compared to revasculariza-
tion (BC) treatments.
DISCUSSION
The treatment eectiveness of pulp revascularization and
apexication in immature necrotic permanent teeth may be similar.
According to our meta-analyses there is no statistically signicant
dierence concerning ‘overall outcomes’ (clinical and radiographic)
and functional retention outcomes between BC revascularization
and MTA or CH apexication.
Comparison of results with previous studies
In our previous systematic review (2017) of randomized clinical
trials, we observed that MTA is likely to result in higher clinical
and radiographic success rates than other endodontic treatments11.
However, despite randomized clinical trials may provide strong
evidence on decision making regarding dierent treatments, these
controlled settings are likely to hamper extrapolation of the studies’
results to daily clinical practice12. Moreover, none of the random-
ized clinical trials assessed functional retention outcomes, which is
deemed as an important outcome in young patients. Thus, well-con-
structed observational studies are also important to be assessed
because there is a tendency that the studies’ results to be closer
to practitioners’ clinics reality. To our knowledge, this is the rst
systematic review and meta-analysis that screened observational
studies to assess clinical, radiographic and functional retention
outcomes in immature necrotic permanent teeth.

Pulp Revascularization or Apexication for the Treatment of Immature Necrotic Permanent Teeth
The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019 doi 10.17796/1053-4625-43.5.1 5
The included studies in this systematic review reported clinical
successes for MTA apexication of 80.77%2, 94.70%1 and 100%6. In
controlled scenarios (randomized clinical trials), clinical successes
were 100% according to Bonte et al.7 and several others4,16-19. On
the other hand, clinical successes of BC revascularization were
76.47%2, 79%6 and 100%1. In randomized clinical trials, clinical
successes were 90% according to Nagy et al.4 and Benzin et al.20 and
100% according to Narang et al.19. Unfortunately, there are several
dierences in the studies’ design that cannot allow a meta-analysis to
be performed between randomized clinical trials and observational
studies. However, according to the individual data aforementioned,
one must expect that MTA apexication is likely to result in higher
success rates, which is in accordance with our previous systematic
review11. Consequently, whenever there is adequate crown-root ratio
in immature necrotic permanent teeth that are not prone to fracture
over time, MTA apexication may be a suitable treatment option.
Despite its advantages, MTA apexication has some inherent
limitations, such as the diculty of placement and cost. Addition-
ally, it is not likely that this technique provides further root matu-
ration4,19. On the other hand, pulp revascularization provides the
possibility of additional root maturation, especially dentinal wall
thickening21 that might strengthen these thin and fragile dentinal
walls, diminishing the incidence of root fracture observed either
with calcium hydroxide7 or MTA apexication2. One point to be
discussed is the proper disinfection of the root canal, as the most
cases of failure in revascularization procedures are due to persistent
infection or reinfection2,6.
Recently, Diogenes et al 22 evaluated concentrations of disin-
fection solutions and intracanal medicaments. Authors reported that
irrigation with 1.5% NaOCl followed by 17% EDTA and intracanal
medicaments with either TAP in concentrations of 0.1-1mg/ml or
Ca(OH)2 with 1mg/ml provide a higher survival of SCAP (stems
cells of apical papilla) that may play an important role in root matu-
ration. Interestingly, the treatment protocols adopted in the included
studies1,2,6 did not use this proposed concentration. Therefore, it is
likely that these higher concentrations of irrigating solutions used
by the authors may be harming the SCAP precluding a potential
benet of root maturation. There is still a necessity of further inves-
tigation on this topic, because most of the failures observed in these
studies were due to persistent infection or reinfection1,2,6.
Jeeruphan et al 1 found a statistically signicant dierence in
root width and length favoring BC revascularization in compar-
ison to CH and MTA apexication. Silujjai and Linsuwanont2
found a statistically dierence increase in root width favoring BC
revascularization when compared to MTA apexication. Alobaid
et al 6 did not observed a statistically dierence among BC revas-
cularization and CH or MTA apexication. In controlled settings,
Narang et al.19 observed an increase of root length and width for
Figure 2. Forest plots of ‘overall outcomes’ (clinical and radiographic) comparing BC
revascularization to MTA and CH apexication.
Figure 3. Forest plots of functional retention outcomes comparing BC revascularization
to MTA and CH apexication.

Pulp Revascularization or Apexication for the Treatment of Immature Necrotic Permanent Teeth
6 doi 10.17796/1053-4625-43.5.1 The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019
BC revascularization when compared to MTA apexication. Nagy
et al.4 observed a statistically signicant increase from baseline of
1.2 ± 0.5 (11.8 ± 4.9) and 0.32 ± 0.12 (12.7 ± 4.7) of root length
and width favoring BC in comparison to MTA. Thus, it seems that
there is an additional increase, mainly in root width in revasculariza-
tion treatments, however, whether this increase is truly from dentin
deposition or cementum-like and bone-like tissue23,24 needs further
investigation.
There are some drawbacks regarding pulp revascularization
treatments, such as root canal obliteration20, crown staining20,25,26,
impossibility of post cementation and diculty of blood clot induc-
tion. Canal obliteration may hamper the future endodontic treatment
if the revascularization technique fail over time. However, it is not
recommended to perform any re-intervention unless treated teeth
become symptomatic27.
Crown discoloration (crown staining) may be an undesirable
event, especially in young patients (teenagers) where esthetic is
considered of utmost importance. This adverse event may be related
to the placement of minocycline or MTA (coronal seal). Alobaid
et al 6 reported that two out of 19 teeth (10.5%) treated with BC
revascularization presented crown staining; however, as the authors
used various types of intracanal medication (including TAP with
minocycline) the main cause of crown discoloration remains uncer-
tain. Bezgin et al 20 reported that 12 of 20 teeth (60%) treated with
pulp revascularization presented crown discoloration. The authors
reported that this adverse event was caused by MTA placement,
despite the use of white MTA instead of grey MTA as coronal
plug20. The fact that the white MTA may induce crown discoloration
is likely to be related to the interaction of its bismuth oxide with the
dentin collagen28.
Apexication treatments may present more favorable results
regarding crown discoloration. On the other hand, patients treated
with pulp revascularization may be beneted with further root
strengthening. Hence, clinicians should balance the importance of
outcomes in each procedure, once inadequate crown-root ratio may
increase the risk of crown or root fractures diminishing functional
retention over time. Moreover, there are some alternatives that
attempt to diminish crown discoloration, such as, sealing the pulp
chamber with dentin bonding agent before placement of TAP or
MTA 20, replacement of the bismuth oxide present in the white MTA
for other components28 or use of biocompatible MTA-like cements29.
Another point of discussion is related to the choice of CH or
MTA for apexication treatments. Jeeruphan et al 1 observed a
success of 77.3% for CH and 94.7% for MTA being the failures
related to catastrophic fractures. It is well known that longer periods
of calcium hydroxide exposure may increase dentin brittleness over
time30,31. This increase in dentin brittleness might be related to the
increased risk of root fracture7. Therefore, as more teeth have been
extracted when treated with CH apexication, it seems that MTA
apexication should be preferred1,7.
In young patients, functional retention in immature necrotic
permanent teeth may be of utmost importance. Thus, asymptom-
atic teeth retained to the age of eighteen might not be considered as
failure, even with presence of periapical lesions, because at this age
patients could choose to have dental implants if necessary. Functional
retention was assessed in all studies1,2,6 included in this systematic
review. Comparing the ‘overall outcomes’ (86%, 116/135 teeth) to
the retention outcomes (90%, 124/138 teeth), the success of treated
teeth raised 4% regarding the treatments performed. More studies
are desirable to evaluate what additional root maturation represents
in terms of root strengthen, and consequently, functional retention
over time. However, one must expect that over longer periods of
follow-up, young patients with immature necrotic permanent teeth
presenting inadequate crown-root ratio may be beneted. Moreover,
pulp revascularization treatments oer the possibility of a second
non-invasive treatment (MTA apexication) if it presents failure
over time.
Strengths of study
This current systematic review included only studies of “high”
quality. The included studies assessed their outcomes over longer
periods of follow-up. We observed low heterogeneity among
included studies.
Limitations of study
Some limitations have to be considered. We included only
three studies in this systematic review with a total of 135 imma-
ture necrotic permanent teeth. The three studies were heterogenic
in some important characteristics, such as the patients age-ranges
and follow-up periods. There is still a need of greater sample size.
Moreover, as we observed few apexication cases in the included
studies, either CH or MTA, we decided to pool them together on
our meta-analysis, however, this should be interpreted with caution,
because the literature clearly point out some advantages of MTA
over CH apexication. There are inherent limitations of observa-
tional studies, such as risk of bias due to case selection and or study
executors’ prejudice. Another limitation may be related to inclusion
of articles published only in English language. However, according
to Moher et al 32 the exclusion of non-English language articles
might not be a limitation on the results of meta-analyses. Therefore,
it is crucial to understand that, at this point, the current evidence
based in observational studies is limited, and that the results may be
consequently biased.
Implications for future researches
Although pulp revascularization procedures may increase root
length and width, some attempts should be made to use standards
methods to quantify the ‘real gain’ in root development, because
some X-ray distortions may overestimate its increase. There is still a
need of establishment of proper concentrations for root canal disin-
fectants that might enhance the survival of SCAP, but also reduce
the microbial load and risk of reinfection.
CONCLUSIONS
Data concerning the current literature in regard to the clin-
ical, radiographic and functional retention outcomes in immature
necrotic permanent teeth treated either with pulp revascularization
or apexication is limited. Based on our meta-analysis, the results
do not favor one treatment modality over the other. More clinical
studies are necessary to further investigate some topics of revascu-
larization and apexication treatments.

Pulp Revascularization or Apexication for the Treatment of Immature Necrotic Permanent Teeth
The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019 doi 10.17796/1053-4625-43.5.1 7
REFERENCES
1. Jeeruphan T, Jantarat J, Yanpiset K, Suwannapan L, Khewsawai P, Hargreaves
KM. Mahidol study 1: comparison of radiographic and survival outcomes
of immature teeth treated with either regenerative endodontic or apexi-
cation methods: a retrospective study. J Endod; 38 (10): 1330-1336. 2012.
2. Silujjai J, Linsuwanont P. Treatment outcomes of apexication or revascu-
larization in nonvital immature permanent teeth: a retrospective study. J
Endod; 43 (2): 238-245. 2017.
3. Simon S, Rilliard F, Berdal A, Machtou P. The use of mineral trioxide aggre-
gate in one-visit apexication treatment: a prospective study. Int Endod J;
40 (3): 186-197. 2007.
4. Nagy MM, Tawk HE, Hashem AA, Abu-Seida AM. Regenerative potential
of immature permanent teeth with necrotic pulps after dierent regenera-
tive protocols. J Endod; 40 (2): 192-198. 2014.
5. Cvek M. Prognosis of luxated non-vital maxillary incisors treated with
calcium hydroxide and lled with gutta-percha. A retrospective clinical
study. Endod Dent Traumatol; 8 (2): 45-55. 1992.
6. Alobaid AS, Cortes LM, Lo J et al. Radiographic and clinical outcomes of
the treatment of immature permanent teeth by revascularization or apexi-
cation: a pilot retrospective cohort study. J Endod; 40 (8): 1063-1070. 2014.
7. Bonte E, Beslot A, Boukpessi T, Lasfargues JJ. MTA versus Ca(OH)2 in
apexication of non-vital immature permanent teeth: a randomized clinical
trial comparison. Clin Oral Investig; 19 (6): 1381-1388. 2015.
8. Galler KM, Krastl G, Simon S et al. European Society of Endodontology
position statement: Revitalization procedures. Int Endod J; 49 (8): 717-723.
2016.
9. American Association of Endodontics. AAE Guide to Clinical Endodontics.
Available at: http://www.aae.org/clinical-resources/aae-guide-to-clini-
cal-endodontics.aspx. Accessed: 2017-06-27.
10. Conde MC, Chisini LA, Sarkis-Onofre R, Schuch HS, Nör JE, Demarco
FF. A scoping review or root canal revascularization: relevant aspects for
clinical success and tissue formation. Int Endod J; 50 (9): 860-874. 2017.
11. Nicoloso GF, Pötter IG, Rocha RO, Montagner F, Casagrande L. A compar-
ative evaluation of endodontic treatments for immature necrotic permanent
teeth based on clinical and radiographic outcomes: a systematic review and
meta-analysis. Int J Paediatr Dent; 27 (3): 217-227. 2017.
12. Van de Sande FH, Collares K, Correa MB, Cenci MS, Demarco FF, Opdam
N. Restoration survival: revisiting patients’ risk factors through a system-
atic literature review. Oper Dent; 41 (S7): S7–S26. 2016.
13. Stroup DF, Berlin JA, Morton SC et al. Meta-analysis of observational
studies in epidemiology: a proposal for reporting. Meta-analysis of obser-
vational studies in epidemiology (MOOSE) group. JAMA; 283 (15): 2008-
2012. 2000.
14. Wells GA, Shea B, O’Connell D et al. The Newcastle-Ottawa Scale (NOS)
for assessing the quality of nonrandomised studies in meta-analyses. Avail-
able at: http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp.
Accessed: 2017-06-27.
15. Chen SJ, Chen LP. Radiographic outcome of necrotic immature teeth treated
with two endodontic techniques: a retrospective analysis. Biomed J; 39 (5):
366-371. 2016.
16. Damle SG, Bhattal H, Loomba A. Apexication of anterior teeth: a compar-
ative evaluation of mineral trioxide aggregate and calcium hydroxide paste.
J Clin Pediatr Dent; 36 (3): 263-268. 2012.
17. El-Meligy OA, Avery DR. Comparison of apexication with mineral
trioxide aggregate and calcium hydroxide. Pediatr Dent; 28 (3): 248-253.
2006.
18. Pradhan DP, Chawla HS, Gauba K, Goyal A. Comparative evaluation of
endodontic management of teeth with unformed apices with mineral
trioxide aggregate and calcium hydroxide. J Dent Child (Chic); 73 (2):
79-85. 2006.
19. Narang I, Mittal N, Mishra N. A comparative evaluation of the blood clot,
platelet-rich plasma, and platelet-rich brin in regeneration of necrotic
immature permanent teeth: a clinical study. Contemp Clin Dent; 6 (1):
63-68. 2015.
20. Bezgin T, Yilmaz A D, Celik BN, Kolsuz ME, Sonmez H. Ecacy of plate-
let-rich plasma as a scaold in regenerative endodontic treatment. J Endod;
41 (1): 36-44. 2015.
21. Jadhav G, Shah N, Logani A. Revascularization with and without plate-
let-rich plasma in nonvital, immature anterior teeth: a pilot clinical study. J
Endod; 38 (12): 1581-1587. 2012.
22. Diogenes AR, Ruparel NB, Teixeira FB, Hargreaves KM. Translational
science in disinfection for regenerative endodontics. J Endod; 40 (4 Suppl):
S52–S57. 2014.
23. Martin G, Ricucci D, Gibbs JL, Lin LM. Histological ndings of revascular-
ized/revitalized immature permanent molar with apical periodontitis using
platelet-rich plasma. J Endod; 39 (1): 138-144. 2013.
24. Becerra P, Ricucci D, Loghin S, Gibbs JL, Lin LM. Histologic study of
a human immature permanent premolar with chronic apical abscess after
revascularization/revitalization. J Endod; 40 (1): 133-139. 2014.
25. Kim JH, Kim Y, Shin SJ, Park JW, Jung IY. Tooth discoloration of immature
permanent incisor associated with triple antibiotic therapy: a case report. J
Endod; 36 (6): 1086-1091. 2010.
26. Gelman R, Park H. Pulp revascularization in an immature necrotic tooth: a
case report. Pediatr Dent; 34 (7): 496-499. 2012.
27. Geisler TM. Clinical considerations for regenerative endodontic procedures.
Dent Clin North Am; 56 (3): 603-626. 2012.
28. Marciano MA, Costa RM, Camilleri J, Mondelli RF, Guimarães BM, Duarte
MA. Assessment of color stability of white mineral trioxide aggregate
angelus and bismuth oxide in contact with tooth structure. J Endod; 40 (8):
1235-1240. 2014.
29. Nosrat A, Sei A, Asgary S. Regenerative endodontic treatment (revascu-
larization) for necrotic immature permanent molars: a review and report of
two cases with a new biomaterial. J Endod; 37 (4): 562-567. 2011.
30. Andreasen JO, Farik B, Munskgaard EC. Long-term calcium hydroxide as
root canal dressing may increase risk of root fracture. Dent Traumatol; 18
(3): 134-137. 2002.
31. Batur YB, Erdemir U, Sancakli HS. The long-term calcium hydroxide
application on dentin fracture strength of endodontically treated teeth. Dent
Traumatol; 29 (6): 461-464. 2013.
32. Moher D, Pham B, Klassen TP et al. What contributions do languages other
than English make on the results of meta-analyses? J Clin Epidemiol; 53
(9): 964-972. 2000.

Pulp Revascularization or Apexication for the Treatment of Immature Necrotic Permanent Teeth
8 doi 10.17796/1053-4625-43.5.1 The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019
Table 1. Detailed characteristics of included studies in the systematic review
Study Jeeruphan et al. Alobaid et al. Silujjai & Linsuwanont
Type of study Retrospective Cohort Retrospective Cohort Retrospective Cohort
Year 2012 2014 2017
Country Thailand United States (US) Thailand
Type of teeth*Anterior and Posterior Anterior and Posterior Anterior and Posterior
Patients (number) BC: 20
CH: 19
MTA: 22
* BC: 17
MTA: 26 (28****)
Teeth (number) BC: 20
CH: 19
MTA: 22
BC: 19
CH: 7
MTA: 5
BC: 17
MTA: 26 (29***)
Age of patients BC: 12.9 ± 5.07 years
CH: 10.5 ± 3.85 years
MTA: 14.6 ± 6.17 years
BC: 8.8 ± 1.6 years
CH: 9.8 ± 2.0 years
MTA: 9.8 ± 2.0 years
8-46 years
Etiology of pulp
necrosis
Trauma (59%), Dens evaginatus
(32,8) and Caries (8.2%)
Trauma (77.4%), Caries (12.9%),
Anatomic anomalies (9.7%)
Trauma (46.51%), Dens evaginatus
(41.86) and Caries (11.63%)
Diagnosis of pulp
necrosis
Clinically and Radiographically Clinically and Radiographically Clinically and Radiographically
Periapical lesion
at the beginning
Either present and absent Either present and absent *
Type of
Intervention
BC, CH and MTA BC, CH and MTA BC and MTA
Type of Irrigating
Solution
BC: 2.5% NaOCl
CH and MTA*
BC: various concentrations of NaOCl,
Chlorhexidine, and/or EDTA
CH and MTA*
BC: 1.5-2.5% NaOCl and 17% EDTA
MTA: 2.5% NaOCl
Type of Intracanal
Medication
BC: TAP (ciprooxacin, metroni-
dazole and minocycline)
CH and MTA*
BC: TAP (ciprooxacin, metronidazole
and minocycline), double antibiotic
(ciprooxacin, metronidazole), and/or
calcium hydroxide
CH and MTA: calcium hydroxide
BC: either ciprooxacin, metroni-
dazole and minocycline or calcium
hydroxide
MTA: calcium hydroxide
Number of clinical
successful cases
BC: 100% (20/20)
CH: 77.3% (17/22)
MTA: 94.7% (18/19)
(BC = MTA > CH (p<0.05))**
BC: 79% (15/19)
CH: 100% (7/7)
MTA: 100% (5/5)
(BC = MTA = CH (p=0.09))**
BC: 76.47% (13/17)
MTA: 80.77% (21/26)
BC = MTA (p>0.05)
Number of
radiographic
successful cases
BC: 100% (20/20)
CH: 77.3% (17/22)
MTA: 94.7% (18/19)
(BC = MTA > CH (p<0.05))**
* BC: 76.47% (13/17)
MTA: 80.77% (21/26)
BC = MTA (p>0.05)
Retention rate BC: 100% (20/20)
CH: 77.3% (17/22)
MTA: 94.7% (18/19)
(BC = MTA > CH (p<0.05))**
BC: 95% (18/19)
CH: 100% (7/7)
MTA: 100% (5/5)
(BC = MTA = CH (p=0.4))**
BC: 88.24% (15/17)
MTA: 82.76% (24/29***)
BC = MTA (p>0.05)
Increase in
root length
(percentage)
BC: 14.9%
CH: 0.4%
MTA: 6.1%
(p<0.001)**
* BC: 9.51% ± 18.14%
MTA: 8.55% ±8.97%
BC = MTA (p>0.05)
Increase in
root width
(percentage)
BC: 28.2%
CH: 1.52%
MTA: 0%
(p<0.0001)**
BC: 10.2% ± 4.0%
CH and MTA*
BC: 13.75% ± 19.91%
MTA: -3.30% ± 14.14%
BC > MTA (p<0.05)
Calcied barrier
formation
* * *
Crown
discoloration
* BC: 2/19 (10.5%)
CH and MTA: 0/12 (0%)
*
Reasons for
failures
CH and MTA: catastrophic
fracture deemed nonrestorable
BC: 3 teeth became reinfected and 1
tooth was retraumatized and extracted
BC: 3 teeth showed persistent infection
and 1 tooth was reinfectioned
MTA: 2 teeth had vertical root fracture,
1 teeth had horizontal root fracture and
2 teeth had unrestorable tooth fracture

Pulp Revascularization or Apexication for the Treatment of Immature Necrotic Permanent Teeth
The Journal of Clinical Pediatric Dentistry Volume 43, Number 5/2019 doi 10.17796/1053-4625-43.5.1 9
Study Jeeruphan et al. Alobaid et al. Silujjai & Linsuwanont
Follow-up
(mean and SD)
BC: 21.15 ± 11.70 months
CH: 27.32 ± 30.47 months
MTA: 14.21 ± 7.84 months
BC: 14 ± 8.5 months
CH: 21.8 ± 12.0 months
MTA: 21.8 ± 12.0 months
BC: 35 ± 21.76 months
MTA: 49 ± 31.09 months
*Authors did not state clearly
** According to authors (p value)
*** Authors stated that 3 patients were unable to attend the recall visits but provided information that teeth were functional with no symptoms
**** Two patients (which did not attend the recall visits) had 3 MTA apexied teeth
Abbreviations: CH: Calcium Hydroxide apexication; MTA: Mineral Trioxide Aggregate apexication; BC: Blood Clot revascularization; TAP: Triple
Antibiotic Paste
Table 2. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomized studies
Study Jeeruphan et al. Alobaid et al. Silujjai & Linsuwanont
1. Selection
1.1. Representativeness of cohorts * * *
1.2. Selection of cohorts
1.3. Ascertainment of treatment regimen * * *
1.4. Demonstration that the outcome of interest was not
present at start of study * * *
2. Comparability
1. Comparability of cohorts on the basis of the design or
analysis
(Age *; other controlled factors *)
** * **
3. Outcome
3.1. Assessment of outcome * * *
3.2. Was follow-up long enough * * *
3.3. Adequacy of follow-up * * *