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ndod Dent Traumatol 1994; 10: 91 93
rinted in Denmark Allrights reserved
Copyright Munksgaard 199
Endodontics
Dental Traumatology
ISSN 0109 2502
M o i s t u r e c o n t e n t o f v i t a l v s e n d o d o n t
i c a l l y
t r e a t e d t e e t h
Papa J, Cain
C,
Messer H H . Mo isture conten t of vital
vs
endo-
dontically treated teeth. Endod Dent Traumatol 1994;
:
91-93.
Munksgaard, 1994.
Abstract
-
T he mo isture content of vital and endo dontically
treated teeth was compared
in
matched pairs
of
contralateral
human teeth extracted
for
prosthod ontic reasons. Samples from
each tooth were weighed then placed in anoven toremovethe
unbound water from the dentin. Weighing was carried outdaily
until
a
constant weight w as achieved
for
three days. The moisture
content was then calculated
and
expressed
as a
percentage
of
the
initial sample weight. Itwas found that vital de ntinhad a
moisture contentof12.35 whilst dentin from end odon tically
treated teethhad a moisture contentof12.10 . These results
indicated that there was
no
significant difierence
in
the moisture
content between endodonticallv treated teeth and vital
teeth.
J .
P a p a C . C a i n H . H . M e s s e r
Department
o
Restorative Dentistry, University
o
Melbourne, Australia.
Key words: teetfi: dentin, dentln brittleness.
Joe Papa, Research Officer, Scfioo l
o
Dental
Science, University
o
Melbourne, 711 Elizabetfi
Street, Melbourne, Australia 3000.
Accepted September 14, 1993
Endodontically treated teeth are widely considered
to
be
more b rittle than vital teeth (1-3 ). This
in-
creased brittleness has been explained by
a
decrease
inthemoisture conten t ofde nti n following lossof
pulp vitality (4).Thestudy ofHeifer et al. 4) is
basedonteeth ob tained from one dog, with pulps
extirpated
at
intervals u p
to
26 weeks before extrac-
tion.
The
dentin
of
pulpless teeth
is
reported
to
have 9 lower mo isture conten t than the den tin of
contralateral vital teeth, with the difference attribu-
table
to
loss of free w ater. Th e find ings of that stud y
are open
to
que stion, since teeth w ere stored
in
saliva before analysis
of
wa ter c on tent. x\lso,
the
sttidydid notshow a progressive lossof moisture
with increasing time after pulp extirpation.
Several recent studies have questioned whether
pulpless teeth
are in
fact m ore brittle th an vital
teeth, based on
a
rang e of biom echan ical properties
and biological features such as the collagen crosslink
content ofdentin (5-7). In a previous studywe
have com pared the strength and toughness of den tin
of teeth obtained from patients und ergoing mu ltiple
extractions
fbr
prostho dontic reasons (7). Each
en-
dodontically treated tooth wascom pared withits
sons.In
view of the lack of difference in bio m ec ha
ical properties that we found
in
that study, we hav
now extended the study
to
re-exam ine the questio
of a difference inmoisture content .
M a t e r ia l a n d m e t h o d s
Twenty-three matched pairs
of
endodontical
treated and vital contra lateral teeth were examined
Prior to extraction, radiographs were examined and
teeth presenting with
a
periapical radiolucenc
were rejected, thus only sound teeth and those with
successful endodontic therapy were included
in th
study.Awide distribution of anter ior a nd posteri
teeth wasincluded. At thetime ofextractionthe
patients ' age andtime since endodon tic treatm en
were recorded. Immediately upon extract ion,
the
teeth were tightly wrapped
in
aluminium foil
and
placed intoa sealed plastic tubeto minimise mois
ure loss.
The teeth were then processed individually,
re-
maining wrapped
and
sealed until required .
Al
sampling procedures were completed asrapidlyas
possible after extra ction (generally within 10 m in)
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P a p a e t a l
clean and the attached periodontal ligament was
scraped ofT until the root surface ap pe are d clean.
The tooth was then placed in a clamping device and
the crown sheared ofT below the c em ento -ena m el
junction (CEJ) with a microtome blade (hit with a
hammer). With vital teeth the pulp was extirpated
using a barbed broach and the canal was super-
ficially filed with Hedstrom files. This was done to
avoid any contribution to the moisture content from
pu lpa l fragments. A section of root den tin (from the
coronal one third) approximately 5 mm long was
then sheared off in the same way. This section was
split into smaller fragments. Each fragment was
examined and any remaining pulp tissue, peri-
odontal tissue or gutta percha was removed. Three
samples from each tooth were then distributed to
three preweighed microfuge tubes at room tempera-
ture and the caps resealed to prevent any moisture
loss. These tubes had previously been desiccated to
constant weight in an oven at 105C. The samples
were then weighed on an analytical balance, accu-
rate to 10 |ig (Sartorius, model 1712, Santorius,
Gottingen, Germany) and returned to the 105C
oven with the tubes unc app ed. Th e vials were subse-
quently capped before removal from the oven and
weighed at room temperature each day until a stable
weight was achieved for at least three successive
days.
Th e initial ( fresh ) a nd final or dr y specimen
Table 1. Moisture content of each matched pair and patient
details.
Patient
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
7
18
19
20
21
22
Age
64
50
74
53
30
30
71
45
45
50
50
50
73
32
61
61
67
67
67
68
68
57
Time since
endo ^
(years)
10
6
16
10
8
8
2
15
15
7
7
7
2
17
5
5
20
20
20
4
4
3
Moisture
vital
11.68
12.14
11.79
12.30
13.18
13.16
11.76
12.31
12.35
12.84
12.01
12.81
12.01
12.10
11.86
11.80
13.57
12.27
12.30
12.04
12.65
12.53
Moisture
vital
10.50
10.86
12.03
12.33
12.42
13.57
12.36
12.43
11.91
11.43
11.03
10.95
11.70
13.53
12.34
11.96
11.82
12.18
12.27
11.76
12.08
13.46
Difference
1.18
1.28
- 0 . 2 4
- 0 . 0 3
0.76
- 0 . 4 1
- 0 . 6 0
- 0 . 1 2
0.44
1.41
0.98
1.86
0.31
-1 .43
-0 .48
-0 .16
1.75
0.09
0.03
0.28
0.57
-0 .93
weights were calculated. The difference betwe
these two measurements would be the amount
unbound water as indicated by the thermogravim
tric studies of Holanger (8), Lim & Liboff (9) a
Heifer et al. (4). The change in weight was e
pressed as a percentage by the following:
Percentage water =
ini t ial weight
final weight
ini t ial weight
X 1
The calculated percentage weight was averaged f
the three vials per tooth.
Random samples containing both the root surfa
and the root canal were taken from the fragments
both endodontically treated and vital teeth duri
processing. These samples were collected into fo
malin and processed for histological examinatio
Transverse sections stained with haematoxylin a
eosin were scrutinised for the presence of any
maining periodontal or pulpal cells which may ha
contributed to the recorded moisture content.
R e s u l t s
The average patient age was 55.9 years and t
time since endodontic treatment was 10.5 yea
The values of the percentage moisture content f
each too th are prese nted in Ta ble 1. Vita l tee
had a moisture content of 12.35% 0 .2 6% wh
endodontically treated teeth had a moisture co
tent of 12.10%
0 . 7 1 % .
The average difference
moisture content between vital and endodontic
ly treated teeth was found to be 0.25% of t
fresh weight. Expressed as a percentage of t
total moisture content, endodontically treat
teeth had 2.05% less water than vital teeth. Th
difference was not significant (P>0.05, paired s
dent /-test).
Histological examination of the samples of den
revealed only occasional small tags of pulpal
periodontal tissue. These were too small to contr
ute significantly to the overall water content of t
samples. Hence it was assumed that the water
moved from the dentin samples was unbound wa
of the dentin and not from extraneous sources.
D i s c u s s i o n
This study was undertaken to determine whether
difference in the moisture content of endodontica
treated and vital teeth could be detected. By taki
pairs of teeth from the same patient, all variab
other than loss of pulp vitality were effectively co
trolled (age, tooth type, degree of dentinal scleros
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should have been more than adequate for any
changes to have occurred.
The vafidity of our findings is dependent on the
reliability of the measurement of moisture content.
Only free water, lost by moderate heating (at 105C)
was measured, since this was the only component
reported earher to be afiected by loss ofpulp vitality
4 .
Precautions were undertaken to avoid both the
loss of moisture before initial weighing and the gain
of moisture durin g the we ighing proc edure after
dehydration. The teeth were wrapped in aluminium
foil immediately following extraction, and samples
were processed within app roxim ately 10 min a nd
sealed in preweighed vials before the initial weigh-
ing. The vials were also sealed before removal from
the oven, to prevent regaining of mo isture. V ariation
among triplicate samples from the same tooth, and
among teeth from different subjects, was small.
The values we have obtained for moisture content
of dentin are co m para ble w ith those reported by
other workers (4, 8, 10). Our sample preparation
techniques included complete removal of peri-
odontal ligament (and also at least some cementum)
and pulp plus predentin, as demonstrated histolog-
ically. The soft tissues have approximately 75
water content (11), and even small tags of soft tissue
could result in a measurable increase in apparent
moisture content. Any small tags of tissue remaining
were equally present in vital and nonvital teeth.
We have not been able to confirm the findings of
Heifer et al. (4) ofa difference in moisture content.
The lack of difference in moisture content and the
previously show n lack of different in biom ec hnic al
properties (7) suggested that the concept of endo-
dontically treated teeth becoming brittle, should be
reconsidered.
o i s tu r e i n v i ta i vs t re a t e d t e e
cknowledgements The authors would like
thank J. Mc Com be, B. Wilson, G. Z ehtab-Ja did
and the staff of the casualty department of the
Royal Dental Hospital of Melbourne for their as
sistance in collecting specimens and Mr. Denni
Rowler for his assistance in preparing histologiea
samples. This study was supported by a gran
from the National Health and Medical Research
Council of Australia.
R e f e r e n c e s
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terior teeth. J Endodf976; 2: 374-5 .
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mo isture con tent of vitaf and pufpfess teeth. Oral Surg Or
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