Effects of Various Irrigating Solutions on the Cleaning of the Root Canal with Ultrasonic Instrumentation
Luiz Pascoal VANSAN
Jesus Djalma PÉCORA
Wanderley Ferreira COSTA
Geraldo MAIA CAMPOS
Faculdade de Odontologia de Ribeirão Preto Universidade
de São Paula, Ribeirão Preto, SP Brasil
Braz Dent J (1990) 1(1): 37-44 ISSN 0103-6440
| Introduction | Material
and Methods | Results | Discussion
| Conclusion | References |
The authors studied, in vitro, by light microscopy and by morphometric
analysis, the cleaning capacity of Dakin's solution, water and Tergentol,
when used as auxiliary solutions to ultrasonic instrumentation of root
canals. After irrigation and instrumentation, 15 extracted human mandibular
incisors, with a single root and with only one canal, were submitted to
routine histological processing with serial 6-µm sections stained
with hematoxylin and eosin. The results showed that Dakin's solution energized
by ultrasound leaves root canals with less debris than Tergentol; water
falls into an intermediate position. The apical third showed more debris
than the middle third, and none of the irrigating solutions left the root
canals free of debris.
Key words: root canal, instrumentation, ultrasound, irrigating
solutions.
Introduction
For nearly a century, many investigators have been searching for irrigation
solutions capable of cleaning and disinfecting root canals (Callahan, 1894;
Walker, 1936; Grossman, 1943; Blechman and Cohen,1951; Varella and Paiva,
1969; Paiva and Antoniazzi, 1973), as well as for an instrumentation technique
able to provide an efficient chemical-mechanical preparation (Badan, 1949;
Richman, 1957; Clem, 1969; De Deus, 1982; Cunningham et al., 1982).
Recently, different devices from those already used in the treatment
of root canals, not only in characteristics but also in functioning such
as sonic and ultrasonic equipment for instrumentation, have been added
to the endodontic arsenal.
Numerous studies have shown the efficiency of ultrasonic instrumentation
in the cleaning of root canals, Richman (1957) being the first to recommend
its use for this purpose.
Cunningham et al. (1982) studied comparatively, in vitro, the effectiveness
of root canal cleaning by ultrasonic instrumentation and by manual instrumentation.
They concluded that root canals instrumented by ultrasound were significantly
cleaner, at all levels, than canals instrumented manually.
Costa et al. (1986) compared, with scanning electron microscopy, manual
and ultrasound instrumentation of root canals observing that ultrasonic
instrumentation was more effective than manual instrumentation in the removal
of dentinal debris.
Also, that same year, Costa et al. (1986) observed, by histological
sections and morphometric analysis, that ultrasonic instrumentation provided
better cleaning of the root canals than manual instrumentation.
The objective of the present study was to analyze, in vitro, the cleaning
ability of Dakin's solution, water and Tergentol, when associated with
ultrasonic instrumentation of root canals.
Material and Methods
Fifteen freshly extracted human mandibular central incisors with only one
canal were used. The teeth were radiographed in the proximal direction
to exclude those that had more than one root canal.
The irrigating solutions used during ultrasonic instrumentation were
Dakin's, Tergentol (lauryl diethyleneglycol ether sodium sulfate, Searle)
and deionized distilled water.
The teeth were placed in individual containers, numbered from 1 to 15,
containing a 0.1% aqueous solution of thymol, with the objective of maintaining
them hydrated and free from microbial proliferation. They were then stored
in the refrigerator at 9°C until use.
The 15 teeth were randomly separated into 3 groups of 5 teeth each,
identified by the irrigating solution used.
The ultrasonic unit Profiendo (Dabi-Atlante, Ribeirão Preto,
SP, Brazil), with a potency of 25 kHz, was used for root canal instrumentation
(Figure 1).
The files used for ultrasound were of the K-Flex type (21 mm; Sybron-Kerr,
São Paulo, Brazil). Kerr files (#15; Sybron-Kerr, São Paulo,
Brazil) were used for the initial manual preparation of the root canals.
Techniques of instrumentation and irrigation
At the time of use, the teeth were removed from the thymol solution
and washed in running water for 1 h. .
The surgery of access to the pulp chamber was performed by the method
recommended by Ingle et al. (1979), and the entrance into the root canal
prepared with a Batt burr, with the pulp chamber always filled with the
irrigating solution to avoid blocking the lumen of the root canal with
particles of dentin.
The full extension of the root canal was then explored by manual instrumentation
(Kerr file #15) establishing as the real working length the distance measured
up to 0.5 mm below the root apex.
Manual instrumentation was performed with a #15 file to dilate the root
canal and allow the introduction of the file energized by ultrasound, so
that it could function freely in the interior of the canal. During this
phase, the canal was irrigated with 2 ml of the irrigating solution. The
ultrasonic unit Profiendo was regulated to allow an irrigating flow of
30 ml/min. The K-Flex file was selected for the ultrasonic system so that
it could freely reach the entire working length.
Each file was used in the interior of the root canal for I minute in
slow, short, back-and-forth movements. In all cases, 3 instruments of increasing
consecutive sizes from the first, which was started by ultrasound, (files
#15, #20, #25, and #30) were used; each canal required 5 min of instrumentation.
After instrumentation, the reservoir of the unit was washed and filled
with distilled water for the final irrigation of the canal with a flow
of 30 ml/min. For this final irrigation, a #15 file was placed in the ultrasonic
unit and introduced into the interior of the already prepared canal for
I min, with care taken not to touch the canal walls.
The same method was used with all of the teeth, only changing the irrigating
solutions tested.
After the chemical-mechanical preparation of the root canals, the teeth
were immersed in a solution of 10% formalin for 48 h, after which they
were submitted to routine histological processing using 6-mm thick transverse
sections stained with hematoxylin and eosin.
Morphometry
For the morphometric study, 10 semi-serial sections of the middle and
apical thirds of each tooth were selected, separating the first section
of every 50 serial sections in each one of the two regions and discarding
the rest.
One of the lenses (6X) of the photomicroscope (Photomax, Olympus) was
fitted with a 400-point grid, with the real space between 2 neighboring
points being 500 mm. The objective used (10X) provided a final magnification
of 60X which permitted an integral panoramic view of the section of dental
tissue.
The points which occurred in two regions of the section - the clean
area and the area with residues - were counted considering the sum of the
points of the two areas as the total area of the root canal, without calculating
the real value in terms of another measuring unit which was not the actual
number of points counted.
After counting the points in the clean area and the area with debris
in the canal, the percentage of the area of debris in the apical arid middle
thirds was counted for each element of the 3 experimental groups, using
the proportional relation between the number of points occurring in this
area and the total number of points included in the area of the canal.
Results
The experimental data used in this study consisted of 3o numerical percent
values resulting from the factorial product of 3 irrigating solutions used
X 2 regions (thirds) of the root canal X 5 replications (teeth): 3 X 2
X 5 = 30. Each numerical value corresponded to the mean of the percent
values (area with debris) calculated in 10 semi-serial histological sections
separated for the study (Table I).
Preliminary tests showed that the sample distribution was normal (with
a probability of 25% for the hypothesis of equality with a normal mathematical
curve) besides being homoscedastic and with an independent variation which
authorized the use of parametric tests (analysis of variance).
The analysis of variance (Table 2) showed statistical significance at
the level of 1% of probability for the 2 factors of variation studied (irrigation
solutions and root thirds), and non-significance for the interaction between
them.
To define which of the irrigation solutions was significantly different
from the others, the complementary Tukey test was used for this factor
of variation (Table 3).
The Tukey test showed a statistical difference between the means of
Tergentol and Dakin's solution with water being in an intermediate position,
without definition if it was statistically equal to Tergentol or to Dakin's
solution.
The statistical non-significance of the interaction of thirds X solutions
indicated by the analysis of variance showed that the increase in the percent
of debris always occurs in the same direction, i.e., from the middle region
to the apical, no matter which solution is utilized.
Discussion
The chemical preparation/mechanical preparation binomial forms the key
requisite for the success of root canal instrumentation. The objective
of these two interdependent factors consists of the cleaning of the canal
and its eventual ramifications removing the largest possible amount of
debris in order to establish ideal conditions which allow a functional
recuperation of the dental organ and a regeneration of tissues eventually
injured by infection.
There appears to be a general consensus that the chemical-mechanical
preparation always leaves debris, organic as well as inorganic, in the
interior of the root canal (Tucker et al., 1976; Moodnik et al., 1976;
Cunningham et al., 1982; Costa et al., 1986). The studies performed have
shown that not all walls of the canal receive the action of the instruments,
commonly leaving areas completely untouched.
The new methods of preparation of the root canal which use energization
by ultrasound allow continuous irrigation with a large volume of irrigating
solution. These methods have been studied extensively to verify their efficiency
in the dentin section as well as their real ability to remove resulting
debris (Martin et al., 1980; Cunningham et al., 1982; Costa et al., 1986).
The results obtained in the present work show that Dakin's solution
(mean = 1.08%) was -the solution which left the smallest amount of residue
in the interior of the canals, followed by water (mean = 2.16%), and finally,
Tergentol (mean = 3.09%), which left the greatest amount of debris (Figure
2).
The fact that Dakin's solution was the best cleaner of the root canal
confirms the findings of Cunningham et al. (1982). This may be due to the
potentiation of the solvent action of the sodium hypochlorite solutions
when energized by ultrasound.
Tergentol, however, when energized by ultrasound allowed the greatest
amount of debris to be left in the interior of the root canals, probably
because of the large quantity of foam formed during the ultrasound energization,
making an efficient contact of the irrigating liquid with the canal walls
more difficult. In fact, it is known that the foam from a detergent can
be eliminated by the addition of an anti-foam agent, and this could explain
the results presented by Tergentol.
In this study, water occupied a position equidistant and statistically
undefined between Dakin's solution and Tergentol. This position is due
only to the mean values compared. In fact, this signifies only that the
test used can consider a difference between the means 3.09 (Tergentol)
and 1.08 (Dakin's solution) as statistically relevant, but cannot confirm
the same in relation to the differences between these 2 and the intermediate
value of 2.16 (water).
None of the irrigating solutions energized with ultrasound studied in
the present work was capable of eliminating all of the debris in the root
canals, since none of them left the root canals completely free of debris.
Conclusion
1. None of the solutions used for irrigation of the root canals, energized
with ultrasound, allowed full removal of the debris from the interior of
the canal.
2. The apical third showed a greater amount of debris than the middle
third, regardless of the solution used.
3. Dakin's solution, as an irrigating solution energized by ultrasound,
left the root canals with less debris than Tergentol.
4. Water, as an irrigating solution energized by ultrasound, occupies
a middle position, undefined between the effective action of Dakin's solution
and the less efficient action of Tergentol.
References
Badan M: Oxigenoargentoterapia. Magi-Mirim, Pacini & Piccolomini, 1949
Blechman H, Cohen M: Use of aqueous urea solution in the field of endodontics:
preliminary report. J Dent Res 30: 503-504, 1951
Callahan JR: Sulfuric acid for opening root canals. Dent Cosmos 36:
957-959, 1894
Clem WH: Endodontics - the adolescent patient. Dent Clin N Amer 13:
483-493, 1969
Costa WF, Antoniazzi JH, Campos MNM, Pécora JD, Robazza CRC:
Avaliação comparativa, sob microscopia ótica, da capacidade
de limpeza da irrigação manual convencional versus ultra-sônica
dos canais radiculares. Rev Paul Odont 8(5): 50-60, 1986
Costa WF, Watanabe I, Antoniazzi JH, Pécora JD, Nuti Sobrinho
A, Lima SNM: Estudo comparative, através do MEV, da limpeza de canais
radiculares quando da instrumentação manual e ultra-sônica.
Rev Paul Odont 9: 10-23, 1986
Cunningham &VT, Martin H, Forrest WR Evaluation of root canal debridement
by the endosonic sinergistic system. Oral Surg 53: 401-404, 1982
De Deus QD: Tempos operatórios do tratamento de canais radiculares.
Endodontia. 4th ed. Medsi, Rio de Janeiro 1986
Grossman LI: Irrigation of root canals. J Amer Dent Ass 30: 1915-1917,
1943
Ingle JI, Beveridge EE: Endodontia. 2nd ed. Pan Americana, Rio de Janeiro
1979
Martin H, Cunningham WT, Norris JP: A quantitative comparison of the
ability of diamond and k-type files to remove dentin. Oral Surg 10: 566-568,
1980
Moodnik RM, Dorn SO, Feldman MJ, Levey M, Borden BG: Efficacy of biomechanical
instrumentation: a scanning electron microscopic study. J Endodont 2(9):
261-266, 1976
Paiva JG, Antoniazzi JH: O use de uma associação de peróxido
de uréia e detergente (Tween 80) no prepare quimico-mecânico
dos canais radiculares. Rev Assoc Paul Cirurg Dent 27: 416-422, 1973
Richman MJ: Use of ultrasonic in root canal therapy and root resection.
J Dent Med 12: 12-18, 1957
Tucker SW, Mizrani S, Seltzer S: Scanning electron microscopic study
of efficacy of various irrigating solutions: urea, tubulicid red and tubulicid
blue. J Endodont 2: 71-77, 1976
Varella JAF, Paiva JG: Manual de endodontia. 2nd ed. Atheneu, São
Paulo 1969
Walker A: A definite and dependable therapy for pulpless teeth. J Amer
Dent Assoc 23: 1418-1425, 1936
Correspondence: Professor Luiz Pascoal Vansan, Faculdade de Odontologia
de Ribeirão Preto, Universidade de Sfio Paulo, 14050 Ribeirão
Preto, SP, Brasil.
|
