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Determining the Optimal Length of The

Tooth's Root Canal Obturation

Article in Research Journal of Pharmaceutical, Biological and Chemical Sciences · November 2016

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 ISSN: 0975-8585

Research Journal of Pharmaceutical, Biological and Chemical

Sciences

Determining the Optimal Length of The Tooth’s Root Canal Obturation.

Emini L1*, Apostoloska S2, Rendzova V2, Ajeti N3, and Kamberi B3.
1Department of Dental pathology and Endodontics, Faculty of Medical science, University of Tetova, Tetovo, FYROM
2Deparment of Restorative dentistry and Endodontics, Faculty of Dental medicine, Ss.Cyril and Methodius University in
Skopje, FYROM
3Department of Dental pathology and Endodontics, Faculty of Medicine-Dental school, University of Prishtina, Kosovo

ABSTRACT

The aim of this paper is to determine, which of the techniques and used materials reaches the ideal
level of obturation of the tooth's root canal, by using micro CT. 80 human extracted frontal teeth were
decrowned 1mm under the cement-dentin junction and were divided in four groups. Group 1,1 (n=20) were
obturated with GuttaFlow®2 system (Coltene/Whaledent GMBh+Co.KG, Langenau, Germany), group 1,2
(n=20) with Thermafill system (Densplay DeTrey GmbH, Konstanz, Germany), group 2,1 (n=20) with AН-Plus®
JETTM (Densplay DeTrey GmbH, Kostanz, Germany) and a single cone technique and group 2,2 with AН-Plus®
JETTM (Densplay DeTrey GmbH, Kostanz, Germany) and a technique of lateral condensation. The samples are
measured in a commercially available clinic for the cone beam micro CT (35, SCANCO Medical AG, Brüttisellen,
Switzerland). Results: Although the Single cone technique has the best final values of filling, the tested
difference between the four groups in relation to the average value of filling, for p>0,05 did not show a
statistically significant difference (Kruskal-Wallis ANOVA test: H=4,0383 p=0,2574). The data in this paper show
that with all four techniques of obturation an ideal length of obturation may be achieved. The material and the
techniques of obturation have no influence on the length of the obturation.
Keywords: root canal, obturation length, micro-CT, Gutta-Flow, Thermafill

*Corresponding author

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INTRODUCTION

The success of endodontic therapy depends on the complete chemical and mechanical treatment of
the canal system of the root of the tooth, followed by obturation of the root canal. The main aim of the
endodontic therapy is the tridimensional obturation of the endodontic space. The efforts for an ideally treated
and sterilized root canal are in question if the same is not completely obturated. The obturation of the root
canal is performed to the site where recovery process of the pulp and periodontal tissue is expected. The
determining of the optimal length of the biomechanical preparation and obturation of the root canal are the
best antimicrobial strategies for the removal of the biofilm (1).

One question still remaining controversial in endodoncy is the length of the canal obturation. The
apical constriction is often described as a referential point to where the canal obturation should be. (2) The
topography of the apical part of the root canal is not standard and often shows variations. (3).

Ponce & Fernandez histologically evaluated the setting of the cement-dentin border and the
diameter of the apical foramen. Their results showed that the cement-dentin border is the point where two
histologically different tissues merge in the interior of the root canal and this point is submissive to changes
depending on the different canal variations. (4) The length of the canal obturation may influence the success
of the endodontic treatment, the prognosis is bad if the root canal is obturated under or over a certain border.

The importance of determining the level of preparation and obturation of the root canal inspired the
usage of different methods for accuracy during work on this endodontic treatment (5,6)

Ricucci stated that for a more successful treatment, the preparation of the root canal should be
completed 0,5mm under the radiological apex, i.e. on the apical constriction where the cement-dentin border
is set. (7)

The per-apical RTG is most commonly used for setting diagnosis, planning and treatment, but its
benefits and limitations are well known. The RTG is a two dimensional picture of a 3 dimensional structure
(8,9), Other models have been used in dentistry as digital radiography, densitometry, CT, MRI and etc. (8,11,9,)
In the early 1990 the researchers Tachibana et al. and Nielasen et al. (1995) used micro CT system to research
the area of endodoncy.

The use of micro CT in endodoncy includes analyses of the inner anatomy of teeth (5,10),
instrumentation of the root canal (8), obturation (12), retreatment of the obturation (12), physical and
biological features of the obturation materials etc.

The aim of this paper is to determine, by using micro CT, which of the techniques and used materials
reaches the ideal level of obturation of the tooth's root canal.

MATERIAL AND WORKING METHOD

This paper includes 80 frontal human extracted teeth. The teeth included are teeth which have curves
of the root canal smaller than 10 (degrees) selected according the technique of Schnider. The experiment does
not include teeth with under developed roots, obturated root canals and caries on the root of the tooth.

After the extraction, the teeth were washed in saline to remove the blood and were kept artificial
saliva.
The teeth were decrowned 1mm under the cement-dentin border and were divided in two groups i.e. four
subgroups.

Group 1(n=40) root canals root canals of teeth treated with a standard technique of treatment.

After determining the exact length of the root canals the teeth from this group were treated
according the technique described by Ingle 1961. A basic apical file was set in the root canal (К-file, Densplay,
Maillefer, Swiss). The file is set at a certain length of the canal. This procedure was performed in all canal walls.
The canals were irrigated with 2ml of NaOCL 5% (Produites Dentares SA, Vevey, Switzerland) and dried with

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paper points. (PRESIDENT DENTAL, Duisburg,Germany). This procedure is performed until the root canal gets a
certain form and has no smell and remains from the pulp tissue.

Group1.1(n=20): root canals of teeth treated with a standard technique of treatment of root canals
and obturated with GuttaFlow ®2.

After the treatment and the irrigation of the teeth's root canals the same were dried and prepared for
obturation. For obturation a GuttaFlow ®2 was used. (Coltene/Whaledent GMBh+Co.KG,Langenau, Germany),
according the instructions of the manufacturer.

Group1.2(n=20): teeth root canals treated according to standard technique of root canals treatment
and obturated with Termafill system.

After preparing the root canals for obturation, in the canal a verificator was set. According the
number on the verificator the size/number of the transporter is determined to use for the canal obturation.
The chosen transporter (Denplay Maillefer, Ballague, Swiss) is disinfected with NaOCL 5% for one minute and
rinsed with 70% alcohol. The root canal is laid with AH-Plus ®JET™ paste (Densplay De Trey GmbH, Kostanz,
Germany) by the help of a lentulus. The transporter is set in the heating system TermaprepPlus® (Densplay).

Group 2 (n=40): teeth root canal treated according an ultrasonic technique for root canal treatment.

The root canals from this group were treated by using an ultrasonic crown-down technique according
to Grecca et al (2007). The treatment was started by a hand widener size 40K-file adjusted to an ultrasound
appliance (Zhengzhou Smile Dental Equipment Co.Ltd.China ), in the period of 1 minute. From this point on,
smaller widener are used till a certain working length is achieved. Circle, slow and short movements are
applied during the work with the appliance. During the use of each instrument the root canals were rinsed
with 5% of NaOCl and dried with paper schtifts.

Group2.1(n=20): teeth root canals treated with ultrasound technique for root canal treatment and
obturated with AH-Plus® JETТМ and single cone technique. The root canal was obturated with the paste AH-
Plus® JETТМ(Densplay De Tray GmbH, Kostanz, Germany) with the help of the lentulus spiral and in the rott
canal only one gutta-percha was set (Coltene/ Whaledent GmbH+Co.KG Langenau, Germany) with a certain
size and length of the root canal.

Group2.2(n=20): teeth root canals treated with an ultrasonic technique for root canals treatment and
obturated with the technique for lateral condensation. The root canals from this group were treated by using
an ultrasound crown-down technique. The walls of the root canals were laid with AH-Plus® JETТМ paste.
(Densplay De Tray GmbH, Kostanz, Germany) with the help of the lentulus spiral. The gutta-percha spikes are
set according the technique of lateral condensation.

The entrance of the root canal after the canal filling in all teeth was obturated with a glass ion cement
(Ketac™Molar Easymix, 3M Deutchland Gmbh, Germany).

Micro-CT evaluation

The samples were measured in a commercial clinic for cone beam micro-CT (µCT 35, SCANCO Medical
AG, Brüttisellen, Switzerland). The samples are wrapped with a piece of sponge with dimensions 2x3cm and
set in special tubes with artificial saliva. The chosen size is 20µm in all three space dimensions. The Rtg voltage
is 70kVp intensity 114 µA. For each sample 700 layers were made. To evaluate the apical part the number of
layers was counted from the apex of the tooth till the layer where the canal obturation appears. The same are
multiplied with 0,02mm which was the width of one layer and the exact space was calculated from the end of
the obturation to the apex.

RESULTS

The descriptive analyses of the final values of each of the four techniques after filling is given in Table
1. Each technique analyzed 20 samples. The average of the final value of filling of the Gutta-Flow technique is

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0,56±0,99mm with a minimal value of -0,26mm and a maximal value of 2,84mm. In this group 50% of the
samples have a final value of filling of 0,17mm. The analyses of the final values of filling got by using the
technique Therma fill pointed out an average value of 0,58±1,2mm and a minimal i.e. maximal value of -
0,46mm v.s. 3,32mm. Fifty percent of the samples in this group have a final value of filling over 0,07mm. The
average of the final value of filling of the Single cone technique is -0,05±0,37mm with a minimal value from -
0,38mm and a maximal value from 0,58mm.

Table 1: Descriptive analyses of the final values according the filling techniques

Technique Number (Means) (Std.Dev.) (Median) (Min) (Max)

Gutta-Flow 20 0,56 0,99 0,17 -0,26 2,84
Thermafill 20 0,58 1,20 0,07 -0,46 3,32
Single cone 20 -0,05 0,37 -0,19 -0,38 0,58
Lateral cond 20 0,03 0,45 -0,07 -0,44 1,08
Kruskal-Wallis ANOVA test: H=4,0383 p=0,2574 *significant for p<0,

In this group 50% of the samples have a final value of filling over -0,19mm. By applying the technique
of Lateral condensation, the average of the final values of filling is 0,03±0,45mm with a minimal value from -
0,44mm and a maximal value of 1,08mm. Although the Single cone technique has the best final value of filling,
the tested difference between the four groups in relation to the average value of filling, for p>0,05 did not
show a statistically significant difference (Kruskal-Wallis ANOVA test: H=4,0383 p=0,2574). The results are
presented in tab.1.

DISCUSSION

The canal obturation represents a stage in the endodontic treatment which is finished with a good
coronary restoration. The increasing failures of the endodontic treatment is connected with an unsuitable
canal preparation and obturation (9,13). The best strategy for reduction of microorganisms is a suitable
preparation, intra-canal medication and a 3d obturation (14).

The choice of a proper length of the canal preparation and obturation is controversial and
complicated as a result of a limited periapical radiography. The exact length of the canal preparation is hard to
be determined with a two dimensional radiography which can have an impact on the further course of the
condition of the periapical region. In the last years the number of laboratory studies in the area of endodontic
research is increasing.

The reason for this is the fact that they are easier and more objective for evaluation especially in
determining the capability for obturation, the length of the canal obturation, the adaptation of the gutta-
percha, the spaces and voids in the canal obturation compared to the root canals in the mouth. From the other
side the clinical studies ask for more time and energy, longer following period and marking of success is more
complicated (15).

The micro-CT is a system for in-vivo studies which can supply a high resolution picture in one quality
and quantity analyses of the tooth and obturation (17).

This technology is used to analyses the dental anatomy, endodontic instruments and methods of
irrigation. It enables an analyses of the volume changes pre and post operation changes of the volume of the
canal (17).

In our paper micro-CT is used to determine the exact length of the canal obturation. The obturation is
done with different techniques of obturation.

In this study the level of apical obturation 0,3-0,6mm under the apical foramen. Our results comply
with the results from previous studies.(18).

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The data from many studies show that when using Gutta-Flow system there is an expansion of the
material used, while at Thermafill system a tendency to contract. This data was not confirmed in our study.
According to the results the canal obturation in all groups is to the ideal level of obturation.

According to the large number of papers realized in vitro the usage of a warm gutta-percha gives
bigger possibilities for extrusion of the material for obturation over foramen apicale. Other authors determine
a smaller rate of overextension in the root canals obturated with the technique of cold lateral condensation
(1,5.20).

Frajlich (21) and Abarca (22) in their papers stated that there has not been a registered statistically
significant difference in the apical extrusion of the material between the treatm,ent with warm and cold gutta-
percha.

The results in this paper comply with the results of Frajlich and Abarca. In our paper the statistical
analyses showed that the material for obturation has no impact on the length of the canal obturation. No
significant difference has been detected between the researched groups. The analyzed values are under the
level of apical foramen. This data do not comply with Gutmann cop, which in there paper state that the
material for obturation has a tendency to extrude on the apical foramen in root canals obturated with
Thermafill system (13).

On the other side many authors state that the results from the simulation models and the extracted
teeth are completely different from the results in vivo.

The authors conclude that there is no doubt that the results from clinical trials are more relevant in
the clinical practice. When comparing the studies which were analyzed , many inconsistencies were observed.
Not only were the defined lengths different, but also location of the teeth. Different intracanal medicaments
were used, the type of obturation material was not the same.

In the analyses of ten clinical studies the results showed an overextension in the root canals
obturated with warm gutta-percha compared to the groups treatde with cold gutta-percha. Results which do
not comply with our results.

CONCLUSION

The data which came out from this paper showed that all four techniques of obturation may achieve
an obturation with an ideal length. The material and techniques of obturation have no influence on the length
of obturation. The same remains to be proven in clinical studies.

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