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Salma El Ashry1, Ashraf Abu-Seida2, Amr
Bayoumi1 and Ahmed Hashem1
1Endodontic Department. Faculty of Dentistry. Ain Shams
University. 2Department of Surgery. Anesthesiology & Radiology.
Faculty of Veterinary Medicine. Cairo University
Pulp necrosis of an immature tooth as a result of caries or trauma could arrest further development of the root, leaving the tooth with thin and weak walls that are prone to fracture.
Endodontic treatment of such a tooth is
difficult because thin walls do not allow much instrumentation, and the obturation might not provide predictable apical seal due to the large opening of the apex.
Conventional treatment of such cases was
multiple-visit apexification using calcium
hydroxide. Although it was successful, it had
several disadvantages including;
unpredictability of apical closure, multiple
visits, probability of canal contamination
between visits, difficulty in follow-up and
subsequent treatment. In addition, long-term
root canal dressing by using calcium
hydroxide weakens the root structure and may
lead to future fracture of the root
Apical barrier technique was introduced as a replacement for apexification with calcium hydroxide. In the apical barrier technique a barrier material is placed at the apex to facilitate obturation procedure. Mineral trioxide aggregate (MTA) is the material of choice for this technique considering its sealing ability, biocompatibility, hard-tissue deposition potential, and the ability to set in the presence of moisture. However, the risk of future fracture may still exist
Recently, regenerative endodontic procedures have gained much attention as it allows root maturation to continue by the generated vital tissue. Presence of a smear layer inhibits the adherence of implanted pulp stem cells, potentially causing failure of the regenerative endodontic treatment. Its removal provides better sealing ability of the endodontic filling material to dentin, and prevents the leakage of microorganisms into oral tissues.
The most commonly used chemical chelating agent to remove the smear layer from root canal walls is 17% solution of EDTA that is used as a final flush. Therefore, the aim of the present study was to investigate the impact of surface modification of dentin using 17% EDTA irrigating solution on the regenerative potential following revascularization of immature permanent non-vital teeth.
This study was conducted according to
the ethical committee protocol at the
Faculty of Dentistry, Ain Shams University,
Egypt.
Sex mongrel dogs (4-6 months) were selected for
this study at Department of Surgery,
Anesthesiology, and Radiology, Faculty of
Veterinary Medicine, Cairo University-Egypt.
Sex dogs
Group I (2 dogs)
(2 weeks)
Blood Clot subgroup
(n=6 teeth)
Blood Clot+EDTA subgroup (n=6 teeth)
Group II (2 dogs)
(6 weeks)
Positive control
Subgroup (n=6 teeth).
Negative control subgroup (n=6
teeth)
Group III (2 dogs)
(12 weeks)
Induction of periapical pathosis: Under general anesthesia, an endodontic
access cavity was done in all experimental and positive control teeth.
The access cavity was left open for four
weeks. Dogs were monitored radiographically for the evidence of development of periapical pathosis. The operated dogs were given oral carprofen tablets daily for 15 days as a pain killer.
Root canal disinfection:
After the infection period, dogs were
anesthetized. The previously infected
experimental teeth were re-entered. The
canals were irrigated using 20 ml of 2.6%
sodium hypochlorite solution and filled
with 1-2 ml of the triple antibiotic paste.
The access cavity was then sealed using
temporary restoration for three weeks.
Treatment protocols:
The teeth were re-entered; the antibiotic
paste was removed by copious irrigation
using hypochlorite 2.6% solution. The
root canals were dried and treated
according to different treatment
protocols as follows:
Subgroup a (Blood Clot or
revascularization):
Hand file size no. 35 was inserted past to
the canal terminus until bleeding was
induced to fill the canal space just below
the cement-enamel junction. MTA orifice
plug was applied to seal the canal orifice.
The access cavity was then sealed using
glass ionomer filling.
Subgroup b (Blood clot and EDTA): Each canal was irrigated with 1ml of 17%
EDTA solution which was kept for 2 minutes inside the canal. The canal was rinsed with another 1ml of 17% EDTA, flushed with normal saline solution and dried by paper points. Similar blood clot induction, sealing of canal orifice and access cavity were carried out as in subgroup (a).
Subgroup c (Positive control):
This subgroup represented the pulp
exposed teeth. Cotton pellets were
inserted into the canal space and no
temporary filling was applied.
Subgroup d (Negative control):
This subgroup represented the
untouched normal teeth.
Radiographic evaluation:
Periapical radiographs were taken before and after induction of the periapical lesion and compared with follow up radiographs taken according to the group. These radiographs were digitized. TurboReg plug-in software was used to standardize these radiographs. Increase in the root length, root thickness and decrease in apical diameter was measured.
Histopathological evaluation:
Assessment of the periapical inflammatory cell scores, periapical inflammatory cell, tissues in-growth in the pulp space, new hard tissue formation, bone / root resorption and apical closure were assessed.
Statistical analysis was performed with
IBM®SPSS®.
Incre
ase
in
th
e
root
len
gth
Subgroups Group I Group II Group III
Subgroup (a) 4.9±1.2 a 13.9±1.8 a 16.3±1.3 a
Subgroup (b) 5.1±1 a 14±1.6 a 16.5±1.4 a
Subgroup (c) 0±0 b 0±0 b 0±0 b
Subgroup (d) 6.2±0.5 a 15.5±0.6 a 19.7±0.4 a
P-value <0.001* <0.001* <0.001*
Incre
ase
in
th
e
root
thic
kn
ess
Subgroup (a) 4±0.6 a 11.4±0.9 a 13.4±0.8 a
Subgroup (b) 4.7±1 a 11.6±0.9 a 13.6±1.3 a
Subgroup (c) 0±0 b 0±0 b 0±0 b
Subgroup (d) 6.1±0.7 a 12.4±1.3 a 15.8±.1 a
P-value <0.001* <0.001* <0.001*
Ap
ical
Clo
sure
Subgroup (a) 2.9±0.9 b 16.4±1.4 b 30.2±1.9 b
Subgroup (b) 3.1±0.9 b 16.5±1.1 b 30.8±1.7 b
Subgroup (c) 0±0 c 0± 0c 0±0 c
Subgroup (d) 6.2±0.6 a 20.5±1.2 a 47±1 a
P-value <0.001* <0.001* <0.001*
*: Significant at P ≤ 0.05, Different letters in the same column are statistically significantly different according to Tukey’s test
Figure 1: Upper radiographs of subgroup (a) (blood clot): preoperative (a) and 2 weeks (b), 6
weeks (c) and 3 weeks (d) following treatment. Lower radiographs of subgroup (c), pulp
exposed teeth (positive control): o days (a), 2 weeks (b), 6 weeks (c) and 3 weeks (d).
Infl
am
ma
tory
sco
res
Subgroups Group I Group II Group III
Subgroup (a) 2.1±0.9 a 1.3±0.5 b 0.4±0.5 b
Subgroup (b) 2.3±0.9 a 1.4±0.5 b 0.6±0.5 b
Subgroup (c) 2.7±0.5 a 2.9±0.4 a 3±0 a
Subgroup (d) 0±0 c 0 ±0c 0±0 c
P-value 0.001* <0.001* <0.001*
Infl
am
ma
tory
cel
l co
un
t
Subgroup (a) 25±1.6 a 16.4±2 b 10.2±1.4 b
Subgroup (b) 25.5±2 a 16.6±1.8 b 10.4±1.7 b
Subgroup (c) 28.4±1.3 a 36.7±1.9 a 38.9±2.9 a
Subgroup (d) 2.5±0.9 c 2.3±1.2 c 2.1±0.9 c
P-value <0.001* <0.001* <0.001*
*: Significant at P ≤ 0.05, Different letters in the same column are statistically significantly different.
Tis
sue
in-g
row
th
Subgroups Group I Group II Group III
Subgroup (a) 0.6±0.5 a 1.3±0.8 b 1.9±0.4 b
Subgroup (b) 0.9±0.4 a 1.9±0.7 a 2.6±0.5 a
Subgroup (c) 0.3±0.5 b 0.9±0.4 b 0.9±0.4 c
P-value 0.099 0.001* <0.001*
Min
era
liza
tion
sco
re
Subgroup (a) 0.4±0.5 a 0.7±0.5 a 1.3±0.5 a
Subgroup (b) 0.6±0.5 a 0.9±0.4 a 1.4±0.5 a
Subgroup (c) 0±0 b 0±0 b 0±0 b
P-value 0.166 0.003* <0.001*
*: Significant at P ≤ 0.05, Different letters in the same column are statistically significantly different according to Mann-Whitney U test
Bon
e re
sorp
tion
Subgroups Group I Group II Group III
No % No % No %
Subgroup (a) 9 75 5 41.6 2 16.6
Subgroup (b) 9 75 5 41.6 2 16.6
Subgroup (c) 10 83.3 12 100 12 100
Subgroup (d) 0 0 0 0 0 0
P-value 0.007* 0.038* 0.002*
Ap
ical
closu
re
Subgroup (a) 0 0 4 33.3 6 50
Subgroup (b) 0 0 4 33.3 6 50
Subgroup (c) 0 0 0 0 0 0
Subgroup (d) 0 0 6 50 7 58.3
P-value NC** 0.295 0.098
Figure 2: (a) Photomicrograph of subgroup II (a) showing dense fibrous connective
tissue in-growth up to apical third of the canal and numerous blood vessels (H & E X
100). (b) Photomicrograph of subgroup III (b) showing tissue in-growth up to middle
third of the canal (H & E X 40). (c) Photomicrograph of subgroup III (b) showing
hard tissue deposition (H & E X100).
Final rinse using 17% EDTA
solution before revascularization
has a positive impact on tissue
interaction along dentinal walls
without modification of the cell
type.