Assessment of dental pulp response to carries via MR T2mapping and histological analysis

Abstract

Objectives
The aim of our study was to assess the correlation between T2 relaxation times and their variability with the histopathological results of the same teeth in relation to caries progression. Materials and methods: 52 extracted permanent premolars were included in the study. Prior to extractions, patients underwent magnetic resonance imaging (MRI) scanning and teeth were evaluated using ICDAS classification. Pulps of extracted teeth were histologically analysed. Results: MRI T2 relaxation times (ms) were 111,9 ± 11.2 for ICDAS 0, 132.3 ± 18.5* for ICDAS 1, 124.6 ± 14.8 for ICDAS 2 and 112. 6 ± 18.2 for ICDAS 3 group (p = 0,013). A positive correlation was observed between MRI T2 relaxation times and macrophage and T lymphocyte density in healthy teeth. There was a positive correlation between vascular density and T2 relaxation times of dental pulp in teeth with ICDAS score 1. A negative correlation was found between T2 relaxation times and macrophage density. There was a positive correlation between T2 relaxation time variability and macrophage and T lymphocyte density in teeth with ICDAS score 2. In teeth with ICDAS score 3, a positive correlation between T2 relaxation times and T2 relaxation time variability and lymphocyte B density was found. Conclusion: The results of our study confirm the applicability of MRI in evaluation of the true condition of the pulp tissue. Clinical relevance: With the high correlation to histological validation, MRI method serves as a promising imaging implement in the field of general dentistry and endodontics.

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Tenyi et al. BMC Oral Health (2024) 24:428
https://doi.org/10.1186/s12903-024-04165-1
Introduction
e degree of pulpal response caused by detrimental fac-
tors in the oral cavity environment is largely dependent
on its potential to resist cariogenic bacterial interactions
on one hand and defensive mechanisms resisting trauma
of the hard dental tissues on the other [1]. Dense vascu-
lar system of the pulp tissue represents a crucial role in
the maintenance of the pulpal homeostasis and oers a
dynamic response to any harmful events. Microvascular
reactions include modifying the local capillary ltration
rate, adjusting the immune and inammatory tissue pro-
cesses and stimulation of angiogenesis [2].
Next to the vascular changes, local injury of the pulp
tissue activates the inammatory cell migration as well.
Soon after the trauma of hard dental tissues or onset of
the infection due to caries progression, several mediators
BMC Oral Health
*Correspondence:
Ana Tenyi
ana.tenyi@mf.uni-lj.si
1Medical Faculty, Department of dental diseases and normal dental
morphology, Hrvatski trg 6, University of Ljubljana, Ljubljana, Slovenia
2Medical Faculty, Institute of histology and embryology, University of
Ljubljana, Ljubljana, Slovenia
3Institute of Radiology, University Medical Center Ljubljana, Ljubljana,
Slovenia
4Medical Faculty, Institute of Physiology, University of Ljubljana, Ljubljana,
Slovenia
5Jožef Stefan Institute, Ljubljana, Slovenia
Abstract
Objectives The aim of our study was to assess the correlation between T2 relaxation times and their variability
with the histopathological results of the same teeth in relation to caries progression. Materials and methods: 52
extracted permanent premolars were included in the study. Prior to extractions, patients underwent magnetic
resonance imaging (MRI) scanning and teeth were evaluated using ICDAS classication. Pulps of extracted teeth were
histologically analysed. Results: MRI T2 relaxation times (ms) were 111,9 ± 11.2 for ICDAS 0, 132.3 ± 18.5* for ICDAS 1,
124.6 ± 14.8 for ICDAS 2 and 112. 6 ± 18.2 for ICDAS 3 group (p = 0,013). A positive correlation was observed between
MRI T2 relaxation times and macrophage and T lymphocyte density in healthy teeth. There was a positive correlation
between vascular density and T2 relaxation times of dental pulp in teeth with ICDAS score 1. A negative correlation
was found between T2 relaxation times and macrophage density. There was a positive correlation between T2
relaxation time variability and macrophage and T lymphocyte density in teeth with ICDAS score 2. In teeth with ICDAS
score 3, a positive correlation between T2 relaxation times and T2 relaxation time variability and lymphocyte B density
was found. Conclusion: The results of our study conrm the applicability of MRI in evaluation of the true condition
of the pulp tissue. Clinical relevance: With the high correlation to histological validation, MRI method serves as a
promising imaging implement in the eld of general dentistry and endodontics.
Keywords Magnetic resonance imaging, Dental pulp, Dental caries, Inammation, Histology
Assessment of dental pulp response to carries
via MR T2mapping and histological analysis
AnaTenyi1*, AleksandraMilutinović2, JernejVidmar3,4, IgorSerša5 and KsenijaCankar4
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Tenyi et al. BMC Oral Health (2024) 24:428
induce transition of the neutrophils, monocytes, T lym-
phocytes and B lymphocytes from the vascular system
into the tissue [3]. ey have multifactorial role which
includes bacterial destruction, cell residues disposal, anti-
gen – representing role, reparation and restoration of the
pulp tissue, promoting stimulation of angiogenesis and
proliferation of the broblasts [4]. In a healthy pulp, B
lymphocytes are uncommon compared to other inam-
matory cells and inltrate tissue in a later phase, after
inammation has already been evolved [5].
With the aim of the acquisition of the three – dimen-
sional images of dental tissues, most commonly used
imaging methods in dentistry include panoramic X –
rays and cone beam computed tomography (CBCT).
Both methods utilize ionizing radiation as a tool for con-
trast gaining, which carries the health risks as well as an
inability to visualize soft tissues, such as the dental pulp.
In contrast,magnetic resonance imaging (MRI) can also
serve as a noninvasive diagnostic tool for assessment
of dental tissues, especially of the pulp, since it enables
the optimization of contrast among various soft tissues
based on the values of T1 and T2 relaxation times of vari-
ous tissues and organs [6–8]. T2 mapping is an advanced
MRI technique used to calculate the T2 relaxation times
of the specic tissues and displaying them voxel-vice on
a parametric map. e T2 relaxation times reect water
content in the respective tissue and are nowadays mainly
used for the evaluation of cardiac edema, e.g., in myo-
cardial inammation or infarction, as well as to describe
the composition of tissues in other pathologies [9]. Over
the recent years, MRI technology has improved diagnos-
tic potential in the several elds of head, oral cavity and
teeth pathology treatment, inlucluding oral and maxil-
lofacial surgery [10, 11], periodontology [12] and general
dentistry [13]. Among other novel treatment modali-
ties in dentistry [14], MRI serves as an excellent tool to
maximize diagnostic certainty which improves treat-
ment outcomes. T2 mapping is proving to be useful for
non-invasive evaluation of caries progression assessed
with ICDAS classication standard [8]. Consequently,
it enables good dierentiation among dierent stages of
soft tissue inammation without the need of contrast
medium and would be an appropriate method for the
early detection of pulpal response to carious lesion [8,
15].
It is important to validate this new MRI method for the
evaluation of dental pulp response to caries progression
before its use in clinical practice. In medicine, the golden
standard is histopathology which is used to validate the
presence and type of a particular disease.
e aim of our clinical/histological study was to assess
the correlation between T2 relaxation times and their
variability with the histopathological results of the same
teeth in relation to progression of carious lesion using
ICDAS coding assessment.
Materials and methods
Ethical statement
e Slovenian national medical ethics committee
approved the study under the protocol number 0120–
415/2020/6. All invited participants received prior infor-
mation and signed the informed consent form.
Participants, MRI protocol, tooth extraction in preparation
for histological analysis
Patients
Fifty-two permanent upper and lower premolars of four-
teen patients, aged from 12 to 20 years, were included in
the study. e teeth were scheduled for extraction due to
orthodontic indication of teeth crowding. Prior to extrac-
tions, patients were scheduled for clinical examination
and assessment of carious lesions on all tooth surfaces
using ICDAS classication [16]. Carries assessments
were performed by a single investigator, as described in
previous studies [8]. According to their corresponding
ICDAS score, teeth were divided into four groups. Group
A: intact teeth with ICDAS score 0, group B: initial cari-
ous lesion with ICDAS score 1, group C: initial carious
lesion with ICDAS score 2, and group D: carious lesion
with visible and palpable enamel cavitation, ICDAS score
3.
MR Image Acquisition
MR imaging was performed on a 3-T whole-body MRI
system (TX Achieva, Philips, Netherlands) with a maxi-
mal gradient strength of 80 mT/m and with the use of a
32-channel receive head coil in all patients on the same
day as the clinical examination. All patients were able
to perform routine daily activities prior to each exami-
nation. e MR protocol consisted of a set of moderate
resolution images to localize the dental pulp anatomy
rst [8]. For T2 mapping, multi-echo-spin-echo (MESE)
T2-weighted sequence in sagittal slices and with a eld
of view that covered most of the pulp chamber was
employed [8]. e parameters of the multi-echo-spin-
echo (MESE) sequence were: TR/TE, 2000/15 ms as well
as 30, 45, 60, 75, 90 ms; eld of view 160 × 160 mm2; slice
thickness 2.5 mm; image acquisition/reconstruction
matrix 380 × 311/560 × 560; acquisition/reconstruction
voxel size 0.42 × 0.51 × 2.5/0.29 × 0.29 × 2.5 mm3; three
slices; gap 0.25; number of signal averages 1; no signal
acquisition acceleration; and acquisition time for all 6
echoes was equal to 10min 24s [8].
MR Data Analysis
e multi-echo-spin-echo (MESE) images were used to
calculate the corresponding maps of T2 relaxation time
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Tenyi et al. BMC Oral Health (2024) 24:428
by using the pixel-wise, mono-exponential, non-negative
least-squares t analysis that is implemented in the MRI
Analysis Calculator plugin (ImageJ, National Institutes of
Health, USA). Finally, from these a T2 map is calculated
[8]. In the next step, T2 values were averaged within each
box to reduce the noise. In this step, pixels with zero T2
values, which lay out of the pulp, were excluded from
averaging [8]. An example of T2 map of patient’s premo-
lar is presented in Fig.1.
Tissue samples and staining
e preparation process of the extracted teeth is shown
in the Fig.2 [17].
Immediately after the extraction, one-third of the api-
cal part of the root was cut o for better penetration of
the xating solution into the pulp tissue and xed in for-
malin for 24h [18].
After 24 h, the entire tooth’s vertical (longitudinal)
split was done. e halves of the tooth with pulp were
re-immersed in formalin for another 48h [17]. en, the
pulps were gently removed from the dental half, dehy-
drated in alcohol, immersed in xylene, embedded in par-
an, and cut into 4.5μm thick longitudinal step serial
sections (Fig.2). e step between the two sections was
20-µm thick [17]. Sections were stored at room tempera-
ture and stained with HE. Blood vessels were shown by
immunohistochemical labeling of endothelial cells with
anti-von Willebrand factor (vWf) (Dako Glostrup, Den-
mark, 1:800) [19].
For demonstration of inammatory inltrate immuno-
histochemical methods using anti – CD 3 (Dako Glos-
trup, Denmark, 1:50), anti – CD 68 (Dako Glostrup,
Denmark, 1:50) and anti – CD 79a (Dako Glostrup, Den-
mark, 1:20) were used, former to display T lymphocyte,
macrophage cells and latter B lymphocyte.
Image analysis and evaluation of the volume density of
blood vessels (Vvasc.)
Image analysis was performed under a light microscope
(Nikon Eclipse E 400), using a camera (Nikon digital sight
DS-M5) and NIS elements version 3 – documentation
computer program. e measurements were performed
on three sagittal slices of the central part of the dental
pulp at the objective magnication of 40x for blood ves-
sels in the whole section (crown and root part) of the
pulp tissue [17].
e volume density of the blood vessels lumen was ste-
reologically analyzed, respectively, using the Weibel’s test
system described previously [20].
Fig. 2 The chart of histological preparation process of the extracted premolars:
Fig. 1 T2 map of a representative patient’s teeth (white arrow) in a sagittal
slice
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Tenyi et al. BMC Oral Health (2024) 24:428
Image analysis and quantication of inammatory
inltrate- density of T lymphocyte, macrophage and B
lymphocyte inltrate (N/mm2)
Image analysis was performed using the same optical
microscope and software as for the analysis of the volume
density of blood vessels. e sagittal slices of the central
part of the dental pulp were rstly outlined at the objec-
tive magnication of 10x, in order to acquire a measure-
ment of the area, which was expressed in mm2. Secondly,
at the objective magnication of 20x, all cells positive to
CD 3 and CD 68, separately, were counted, consequently
gaining the density of T lymphocyte and macrophage
inltrate.
All cell countings, including those of inammatory
cells as well as blood vessel cells and MRI T2 relaxation
times were performed separately, for the crown part and
root part of the tooth sample.
Statistics
Mean signal values and variability of T2 relaxation times
in distinct regions of interest (ROI) on T2-weighted
images were obtained. Statistical analysis was performed
using SigmaPlot 14.0 (Systat Software, Inc., USA). Shap-
iro-Wilk test and Brown-Forsythe were used to check for
normality and equal variance. One-way analysis of vari-
ance (ANOVA) was used to test for dierences between
parameters. In cases when Shapiro-Wilk or Brown-
Forsythe test failed, Friedman ANOVA on Ranks was
performed. If ANOVA showed statistically signicant
dierences between groups of data, Dunnett’s method for
multiple comparisons was used. e level was set at 𝑝 <
0.05 for all statistical signicances.
e sample size was determined, using the power of
the study at 0.8 and p - value signicance at < 0.01. e
result of appropriate sample size was N = 19. Our study
involved 52 specimens.
e correlation between the volume density of blood
vessels, T lymphocyte inltrate density, B lymphocyte
inltrate density, macrophage density and corresponding
T2 relaxation times acquired by MRI, were tested by the
Pearson coecient of correlation (p < 0.05).
Results
Fifty-two upper and lower permanent premolars of four-
teen patients (nine female and ve male) were included in
the study. Mean age was 14,2 ± 1,97 years.
Findings of caries progression assessment (ICDAS)
Each extracted premolar had at least one initiate cari-
ous lesion visible on its surface. When several carious
lesions were visible on the same tooth, code with a higher
ICDAS score was noted and included in statistic calcula-
tion. No grater carious decay than ICDAS 3 were present
on extracted teeth. All carious lesions were assessed as
inactive type with ceased progression.
MRI results; T2 relaxation times
Mean T2 relaxation times and variability of T2 relaxation
times in the groups of teeth from ICDAS 0 to ICDAS 3
are shown in Table1.
Qualitative and quantitative ndings of tissue samples
Pulp vascularity
Histological examination of the pulps stained immuno-
histochemically for von Willebrand factor showed endo-
thelial cells of blood vessels (Fig.3). In each specimen,
crown part of the pulp tissue contained arterioles with
very thin and in few voxels even absent muscular stra-
tum. Towards the odontoblastic layer arterioles presented
much more branched appearance, which later formed
into capillary nets. Capillary mesh was the densest in
the cell free zone (Weil layer). In the radicular part of the
pulp tissue, the vascular microstructure was dierent,
represented by only one or few vessels with wider diam-
eter compared to those seen in the crown. ese vessels
extended parallel to the root axis, but later lengthways
toward the crown, they ran perpendicular and became
smaller, presenting with lesser diameter. Vascular volume
densities are presented in Table1, grouped according to
the level of progression of the carious lesion from ICDAS
0 to ICDAS 3.
Inammatory inltrate
Out of 52 specimens, two separate samples of each stain-
ing with anti – CD 3 and anti – CD 68 for demonstration
of T lymphocyte and macrophage inltrate, respectively,
were rinsed o the slides due to technical diculties
associated with small amount of pulp tissue material.
Consequently, those samples were not available for inclu-
sion in the statistics, which was therefore performed on
the remained 50 samples.
Cell inltrate in dierent extent and dispersion was
seen in slides of each and every extracted tooth, regard-
less of the presence or absence of caries lesion at its
surface (Fig. 2). Inammatory inltrates were mostly
localized in the sub - odontoblastic zone, near cell rich
zone (Höhl’s layer).
e average density of macrophage, T lymphocyte and
B lymphocyte inltrate, separately, are listed in Table1.
Correlations between measured parameters
A positive correlation was observed between T2 relax-
ation times and macrophage and T lymphocyte density in
healthy teeth (Table2).
ere was a positive correlation between vascular
volume density and T2 relaxation times of dental pulp
in teeth with ICDAS score 1. In contrast, there was a
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Tenyi et al. BMC Oral Health (2024) 24:428
negative correlation between T2 relaxation times and
macrophage density.
ere was also a positive correlation between T2 relax-
ation time variability and macrophage and T lymphocyte
density in teeth with ICDAS score 2.
In teeth with ICDAS score 3, a positive correlation
between T2 relaxation times and T2 relaxation time vari-
ability and lymphocyte B density was observed.
Discussion
Our results show an increase in vascular density and T2
relaxation times in teeth with ICDAS score 1. e inam-
matory cells, such as T lymphocyte and macrophages, are
present in healthy as well as in the teeth with caries. In
latter, the values were signicantly higher [3, 5]. In con-
trast, B lymphocytes appear only in carious teeth [5].
A positive correlation was observed between T2 relax-
ation times and macrophage and T lymphocyte density
in healthy teeth. In teeth with ICDAS score 1, there was
a positive correlation between T2 relaxation times and
Fig. 3 Dental pulp of a lower premolar assessed with ICDAS 2 score, stained with anti- vonWilendbrand factor (vWf), anti – CD68, anti – CD3 and anti –
CD79a (objective magnication from left to right: × 2, bar = 1000μm; × 10, bar = 200μm; × 20, bar = 100μm). Note that the target cells are revealed in
brown colouration
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Tenyi et al. BMC Oral Health (2024) 24:428
vascular volume density and a negative with macrophage
density. ere was also a positive correlation between T2
relaxation times and B lymphocyte density in teeth with
ICDAS score 3.
We observed the inammatory cells, such as T lympho-
cyte and macrophages in healthy as well as in the teeth
with caries. ese results are in agreement with study of
Opasawatchi et al. (2022), where T lymphocyte and mac-
rophages were presented in healthy as well as in the cari-
ous teeth, whereas macrophage inltration was seen in
greater extent in carious infected pulps [21]. In addition,
with the higher ICDAS score, we observed more pro-
nounced macrophage inltration along with moderate
increase of lymphocyte inltration. e possible explana-
tion is that the intensity of pulp tissue response to mac-
rophage inltration increases with the degree of carious
lesion and greater permeability of hard dental tissues, as
shown in previous studies [21, 22].
Similar as in our study, Tomaszewska et al. performed
analysis on non – carious orthodontically extracted
upper premolars using immunohistochemical staining of
inammatory cells with anti – CD 68 and blood vessels
with anti – CD 31 [23]. eir results showed the presence
of inammatory inltrate and cell atrophy even in pulps
of intact teeth, without any caries or trauma visible on
their surface. e mentioned authors suggested inam-
mation might be caused by the fact that all patients had
tooth crowding and malocclusion. According to men-
tioned study, it is possible the inammatory inltrate
seen in our histologic slides might as well be due to orth-
odontic factor and not only due to carious lesion, since
our study was also performed on the patient’s teeth with
orthodontic diagnosis.
In our study, every lesion was inactive and all partici-
pants reported no symptoms, nor pain or discomfort
regarding having a carious lesion. Considering this, all
Table 1 Mean T2 relaxation times and variability of T2 relaxation times (as means ± SD), vascular density, macrophage, T lymphocyte
and B lymphocyte density (as median (25% percentile, 75% percentile)) in groups of teeth with distinct ICDAS scores
Group (ICDAS) A (ICDAS 0) B (ICDAS 1) C (ICDAS 2) D (ICDAS 3) p value
N = 15 N = 7 N = 13 N = 17
T2relaxation times (ms) 111.9 ± 11.2 132.3 ± 18.5* 124.6 ± 14.8 112. 6 ± 18.2 0.013
T2relaxation time variability (ms) 44.6 ± 4.9 46.6 ± 9.3 39.0 ± 5.5 38.6 ± 6.2† 0.007
Vascular volume density (mm3/mm3) 0.219
(0.09; 0.29)
0.301
(0.29; 0.32) *
0.279
(0.19; 0.31)
0.221
(0.16; 0.28) ‡
0.023
Macrophage density (N/mm2)5.847
(2.30; 7.18)
19.894
(11.89; 25.92) *
27.500
(7.17; 41.07) ⁑
23.288
(16.15; 61.15) †
< 0.001
T lymphocyte density (N/mm2)1.734
(0.71; 3.03)
7.778
(3.99; 12.11)
10.000
(5.52; 13.13) ⁑
5.000
(1.81; 13.40) †
0.001
B lymphocyte density (N/mm2)0.000
(0.00; 0.13)
0.160
(0.13; 0.78)
2.240
(0.59; 4.007) ⁑
1.989
(0.81; 9.57) †
< 0.001
*- statisti cally signicant die rence between group A (I CDAS 0) and B (ICDAS 1)
⁑- statistic ally signicant dier ence between group A (I CDAS 0) and C (ICDAS 2)
†- statisti cally signicant dier ence between group A (I CDAS 0) and D (ICDAS 3)
‡- statist ically signicant di erence between grou p B (ICDAS 1) and D (ICDAS 3)
Table 2 Correlations between measured parameters in the teeth with distinct ICDAS scores
Vascular volume den-
sity (mm3/mm3)
Macrophage density
(N/mm2)
T lymphocyte den-
sity (N/mm2)
B lym-
phocyte
density
(N/mm2)
Group A
(ICDAS 0)
T2 relaxation times (ms) NS R = 0.599
p = 0.0397
R = 0.741
p = 0.00901
NS
T2 relaxation times variability
(ms)
NS NS NS NS
Group B
(ICDAS 1)
T2relaxation times (ms) R = 0.812
p = 0.0251
R = − 0.821
p = 0.0253
NS NS
T2relaxation times variability (ms) NS NS NS NS
Group C
(ICDAS 2)
T2relaxation times (ms) NS NS NS NS
T2relaxation times variability (ms) NS R = 0.598
p = 0.04
R = 0.620
p = 0.0316
NS
Group D
(ICDAS 3)
T2relaxation times (ms) NS NS NS R = 0.747
p = 0.000875
T2relaxation times variability (ms) NS NS NS R = 0.634
p = 0.00831
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Tenyi et al. BMC Oral Health (2024) 24:428
pulps were clinically considered to be healthy. In daily
clinical practice, dentists are confronted with much more
challenging situations, where pulp might be mild, mod-
erately orseverely inamed, even partially necrotic [24].
e correlation between the clinical status of the pulp
and its histological state was assessed in many studies, in
which no strong connection of histological pictures and
clinical signs were conrmed [24–26].
In the present study, an increase of both, T2 relaxation
times and vascular density, in teeth with ICDAS score 1
and their positive correlation was observed. An increase
in T2 relaxation times is in agreement with the physi-
ological response of the vascular pulp tissue to infec-
tious carious disease at its early stage [8]. is could be
explained with the observed increase in vascularity due
to hyperaemia and angiogenesis [27]. In teeth with higher
ICDAS scores, the decrease of T2 relaxation times is
observed, suggesting that more inammatory cells inl-
tration prevails over vascularity in the pulpal tissue. In
our study, this was conrmed with the progression of
macrophage inltration in ICDAS scores 2 and 3. Addi-
tionally in these, ICDAS scores along with the progres-
sion of inammatory cells inltration, moderate positive
correlations were observed with T2 relaxation time vari-
ability. is could be explained by greater tissue inhomo-
geneity, due to vascular density decease and increase in
inammatory cells inltration, that progressed from the
crown to the root part of the pulpal tissue.
In our study, the B lymphocytes appear only in carious
teeth. is is in agreement with the ndings of previous
studies, which concluded, that there is usually a lack of
B lymphocytes in a healthy pulp [5]. In contrast, they
inltrate tissue in a later phase, after inammation has
already been evolved [5]. is could be conrmed by our
results. Namely, we observed strong positive the corre-
lation between B lymphocytes density and the T2 relax-
ation time and its variability in teeth with ICDAS score 3.
Our study has several limitations. Firstly, it must be
noted that teeth included in the study were not all from
dierent patients and were therefore in principle not
entirely independent. At least 2 and mostly 4 teeth from
the same patient were included in the study and observed
in one examination in the same eld of view. is was due
to our eorts to maximize the number of studied samples
and due to limited availability of MRI for the study. In
addition, average values of T2 relaxation times were lower
than those seen in the study of Cankar et al. [8], espe-
cially in the group of healthy teeth (ICDAS 0). is could
be explained by the age dierence. e patients included
in the present study are younger and the dierence might
occur due to the inuence of age on the pulpal tissue.
Lastly, comparison of T2 relaxation times among dierent
ICDAS scores in the present study is limited due to the
fact that our study did not include teeth with deeper and
more extensive carious lesion (ICDAS 4, 5 and 6).
Conclusion
e results of the present study conrm that the dier-
ence in the dental pulp tissue between teeth with ICDAS
score 0 and teeth with ICDAS score 1 is well presented
in T2 relaxation times. In contrast, in teeth with ICDAS
score 2 and 3, the progression of inammation favours
positive correlation between T2 relaxation time variabil-
ity and inammatory cells inltration, possibly due to
greater tissue inhomogeneity. In teeth with ICDAS score
3, the T2 relaxation time and its variability, correlate with
B lymphocytes inltration.
Acknowledgements
This manuscript retains overlapping passages in the Methods section, which
is due to the fact that identical protocol was used in the two previous studies
- MRI study by Cankar K, Vidmar J, Nemeth L, Serša I (2020) T 2 Mapping as
a Tool for Assessment of Dental Pulp Response to Caries Progression: An in
vivo MRI Study. Caries Res 54:24–35., https://doi.org/10.1159/000501901 and
histological study by Tenyi A, Nemeth L, Golež A, et al. (2022) Comparison of
the vitality tests used in the dental clinical practice and histological analysis of
the dental pulp. Bosn J Basic Med Sci 22:374–381. https://doi.org/10.17305/
bjbms.2021.6841. This are the original source of method descriptions, which
are as well cited in the manuscript.
Author contributions
All individuals listed as authors agree that they have met the criteria of
authorship, agree to the conclusions of the study and that no individual
meeting the criteria of authorship has been omitted.T. A.: Contributed to
conception, design, data acquisition and interpretation, drafted and critically
revised the manuscript.M. A.: Contributed to conception, design, data
acquisition and interpretation, drafted and critically revised the manuscript.V.
J.: Contributed to conception, design, data acquisition and interpretation,
drafted and critically revised the manuscript.S. I.: Contributed to conception,
design, data acquisition and interpretation, drafted and critically revised the
manuscript.C. K.: Contributed to conception, design, data acquisition and
interpretation, performed all statistical analyses, drafted, and critically revised
the manuscript.
Funding
This work was supported by the program grants of the Slovenian Research
Agency, ARIS P3-0019.
Data availability
The datasets used and analysed during the current study are available from
the corresponding author on reasonable request.
Declarations
Ethical approval and consent to participate
The Slovenian national medical ethics committee approved the study under
protocol number 0120–415/2020/6. All invited participants received prior
information and signed the informed consent form.
Consent for publication
Not applicable.
Conict of interest
The authors declare no conict of interest.
Received: 3 January 2024 / Accepted: 19 March 2024
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

Page 8 of 8
Tenyi et al. BMC Oral Health (2024) 24:428
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