Martin Hashemi
2016/2017, group 15
EFFICACY OF MAXWIRE® ALLOY FILE IN REMOVING
THE REMAINS OF ROOT CANAL FILLING MATERIAL
IN VITRO
Master`s ThesisDR. Greta Lodiene
Masters in Odontology, Martin Hashemi
LITHUANIAN UNIVERSITY OF HEALTH SCIENCES MEDICAL ACADEMY
FACULTY OF ODONTOLOGY
DEPARTMENT OF DENTAL AND ORAL PATHOLOGY
EFFICACY OF MAXWIRE® ALLOY FILE IN REMOVING THE REMAINS OF ROOT CANAL FILLING MATERIAL IN VITRO
Master`s Thesis
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TABLE OF CONTENTS
SUMMARY……….9
INTRODUCTION………..10
REVIEW OF LITERATURE……….12
MATERIAL AND METHODS………..15
1. Preparation and filling of root canals………..15
2. Root canal retreatment………17
3. Radiographic evaluation……….18 4. Statistical analysis………...19 RESULTS………...20 DISCUSSION……….24 ACKNOWLEDGEMENT………..26 CONFLICT OF INTERESTS………26 CONCLUSION………..26 PRACTICAL RECOMMENDATIONS………....26 ETHICAL STATEMENT………..27 REFERENCES………...27
Page 9
Efficacy of MaxWire® alloy file in removing the remains of root canal filling material in vitro SUMMARY
Aim:
To evaluate the efficiency of MaxWire® alloy file in removing root canal filling material after retreatment with endodontic retreatment instruments.
Materials and methods:
Distal roots of twenty human mandibular molars with single and straight canals were selected for this study. All canals were instrumented up to #40/.04 with Bio-race system (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and apical preparation was finished with K-file #50/.02 (MANI INC., Utsunomiya, Tochigi, Japan). Obturation was performed using lateral condensation technique with ADSEAL sealer (META BIOMED CO., LTD., Cheongju-si, Chungbuk, Korea). Radiographs were performed in buccolingual and mesiodistal directions with periapical X-ray after obuturation. Teeth were randomly divided into two groups with ten teeth in each. Group 1: removal of root canal filling material was performed using D-race system (FKG Dentaire, La Chaux-de-Fonds,
Switzerland). Group 2: removal of root canal filling material was performed using D-race system (FKG Dentaire, La Chaux-de-Fonds, Switzerland) following XP endo Finisher R instrument (FKG Dentaire, La Chaux-de-Fonds, Switzerland). Radiographs were performed after retreatment. Residual material was calculated in percentage left in canals. Statistical significance between the two groups were analyzed with t-test.
Results:
Remnants of root canal filling material was observed in both groups: 38.90% in Group 1 and 13.71% in Group 2, respectively. There was a significant difference between the groups in term of the total root canal filling material (p<0.05).
Conclusion:
MaxWire® alloy file significantly increased the amount of removed root canal filling material after retreatment with endodontic retreatment instruments.
Keywords:
Page 10
INTRODUCTION
Today it is more and more preferred to preserve teeth with promising prognosis rather than to extract them. This leads to even more endodontic retreatment cases. Retreatment in endodontics includes complete removal of root canal filling materials, disinfect, re-establish working length and re-obuturate the root canal [1].
There are so called “usual suspects” (not enough cleaning and disinfecting of canal, not working to full working length, not having good apical seal etc.) that should be kept in mind while carrying out the endodontic treatment. Keeping this in mind will not only improve the endodontic quality, but also maximizes the rate of success. It is recommended to do regular follow ups to assess the
outcome, which should be done on a yearly basis to monitor any changes. However retreatments are in many cases needed despite doing a very precise treatment. According to studies about 86–98% treatments are successful overall [2].
Endodontic retreatment is a procedure that often arise, and when it does, is always a challenge in finding the best outcomes. One of the most important things in order to avoid failure is to remove root canal filling material as precise as possible, which makes choosing the system also important and hard because of the wide variety of choices.
This leads to a variety of proposed techniques of endodontic retreatment: endodontic hand files, Nickel Titanium rotary instruments, Gates Glidden burs, heated instruments, ultrasonic instruments, the use of laser, and the use of adjunctive solvents [1].
The efficiency and the precision of retreatment files to remove filling material are important factors of successful treatment. The biggest challenge for these retreatment instruments is to follow the canal anatomy precisely enough in order to remove all root canal filling material. Improvements of the retreatment files suggest that the new XP‐endo® Finisher R files remove more precisely and effectively than older ones [3].
The main problem with endodontic retreatment is that the instruments do not provide a 100% efficiency in removal of root canal filling materials which leads to a continuous development of these systems.
New retreatment instrument made from NiTi MaxWire® material, XP‐endo Finisher R (FKG Dentaire, La Chaux-de-Fonds, Switzerland), offers higher flexibility and
Page 11 access and cleaning properties due to very good resistance to instrument fatigue due to its zero taper #30/.0 and the ability of the file to work in mixed phases which are exclusive for FKG MaxWire® alloys (martensitic-phase of 20 oC and austentic-phase of 35 oC). Adaptation to canal morphology and preservation of the dentine. XP-endo Finisher R (FKG Dentaire, La Chaux-de-Fonds,
Switzerland) is only one file and has according manufacturer unique characteristics as: mechanical cleaning of the canal in areas previously impossible to reach due to its incredible flexibility. Thorough removal of residual obturation material during retreatment. This promises better and more reliable results in retreatment procedures [4].
Because of new XP-endo Finisher R‘s (FKG Dentaire, La Chaux-de-Fonds, Switzerland) promising functions it was chosen for the study. The comparing system in removing root canal filling material was chosen by evaluating studies of previously used retreatment files, preferably from same
manufacturer (evaluation is done in “Review of Literature” part on page 12).
The aim of this research was to evaluate the efficiency of MaxWire® alloy file in removing root canal filling material after retreatment with endodontic retreatment instruments.
Tasks:
1. To evaluate the efficacy of removing root canal filling material using D-race retreatment instruments.
2. To evaluate the efficacy of removing root canal filling material using D-race retreatment instruments following MaxWire® alloy file XP-endo Finisher R.
The hypothesis is that MaxWire® alloy file is effective in removing root canal filling material after retreatment with endodontic retreatment instruments.
Page 12
REVIEW OF LITERATURE
There has been many researches performed previously to evaluate the efficiency of removing root canal filling materials [5, 6, 7, 8, 9, 10, 11].
T.Rödig et al. (2012) compared D-race system with ProTaper Universal Retreatment instruments and Hedström files in efficiency of removing root canal filling material and the time it took to perform. This study showed that D-race were the most effective of three. Hedström files, which are hand files, were the least effective of them all. This concludes that rotary files are more efficient then hand files even if there is an increased risk of separating instrument, causing ledges or perforations [5].
Opposite results were observed by JS. Dhillion et al. (2014) were Hedström files, Protaper files and Protaper retreatment files were evaluated and compared. It was concluded that all the instruments had the same effect and that there was no significant difference [6]. All teeth were instrumented (maxillary incisors) to #50 which is correct according to “morphometric and anatomical studies of the root canal system” [12] (Fig. 1). Here are described all the recommended apical sizes for endodontic preparations in order to minimize the risk for retreatments. However in retreatments there may always be a necessity to increase the apical size additionally in order to remove sufficient amount of root canal filling material. Preparing canals to correct apical sizes may have had an effect to the results of the research that are more reliable.
Page 13 In Bahareh et al. (2011) research Mtwo R, Mtwo R with solvent, ProTaper, ProTaper with solvent were evaluated. It was observed that Mtwo R in apical region was more effective with solvent and less in the rest of the canal. ProTaper system was less effective in apical region with solvent but more efficient in rest of canal [7]. Within this study it was shown the difference a solvent can make, both in a positive and negative way. These systems should have had an additional system added, i.e. a hand file in bigger apical size to remove apical remnants more efficiently.
Silva EJNL et al. (2015) performed a study were ProTaper Retreatment System and WaveOne System were evaluated. No solvents were used, which would provoke different results than if the operators would have used solvent. In clinical case, if there is a necessity then a solvent can be used, which will change the final result [7]. It was concluded that there were no statistical difference between the systems [8].
Preetam C S et al. (2016) conducted a study were operators compared ProTaper Retreatment System, D-race and Hedström files. They were removing the crown of the tooth in order to get a good access to the canal. This might increase the efficiency of the retreatment and would not have been done in clinical case. Operators did not mention how they divided the parts of the tooth for examination (cervical, middle, apical). The results showed that cervical and middle parts of the teeth the rotary files were best, but in the apical part the Hedström files was better in removing root canal filling material [9]. Even though the apical preparation was better with Hedström files, the overall preparation was significantly better with rotary files.
Zahra Sadat Madani et al. (2015) compared the efficacy of D-RaCe, ProTaper retreatment kit and hand H-files in removal of obturating materials. The results showed that D-race had the least amount of residual filling material in total, but that H-files were the best ones in apical part [10]. This shows that rotary retreatment files are limited in apical region in retreatments.
I. Abramovitzl et al. (2012) compared the efficiency of removing root canal filling by using ProTaper Universal retreatment files with/without Self-Adjusting File (SAF). One of the mesial canals of mandibular molars was shaped with Protapers until F2 and was continued with hand files until #30- #45, according to “morphometric and anatomical studies of the root canal system” [15]. This study shows a good increase in removing residual root canal filling material with an additional retreatment file. The second system increased the cleaning efficiency up to 60% [11].
Page 14 AlShwaimi E(2017) compared the cyclic fatigue properties of files made using controlled memory Ni-Ti technology with those of files made from M-wire. ProFile Vortex were compared to
Proflexendo files. The study showed Manufacturing technique had a significant impact on the resistance to cyclic fatigue. Files made from controlled memory Ni-Ti technology had the highest number of cycles to failure compared to files made from M-wire files with similar taper and tip size. [16].
For evaluation of root canal filling remnants previously CBCT has been used [10] as well as Micro-CT [5,17] with perfect results. There were also several researches that found sufficient enough to make a good estimation of how much residual filling material is in each part of the canal (cervical, medial and apical) by performing periapical rays in different angles and after dividing these X-rays in the three previously mentioned parts (cervical, medial and apical). Periapical X-X-rays were chosen for this study after several studies proving their efficiency and because of its simplicity in executing [6, 8, 9, 11].
With these studies being made, one can now conclude that D-race system had a good retreatment ability and ProTaper was almost as good, but is the best when used in combination with an
additional file [5, 9, 11]. In this research D-race system will be combined with XP-endo Finisher R to compare with only using D-race as a retreatment system.
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MATERIALS AND METHODS
Distal roots of twenty human mandibular molars with single and straight canals were selected for this research. Only teeth with minimal restorations or caries lesions and non-fused, well-developed roots were chosen for the presented research (Fig. 2).
Fig. 2: Representative radiograph with an acceptable tooth for this research.
Preparation and filling of root canals
The research was carried out using 20 extracted human mandibular molars. Standard access cavities were prepared and the canal orifices were located. Teeth with single and straight distal canals were selected for this research. Bucco-lingual X-rays were performed using (EasyDent V4 Viewer, software Version 4.1.3.2, by VATECH, New York, USA). A silicone mold was made in order to hold the teeth in a correct and repeatable position (Fig. 3).
Page 16
Fig. 3: A silicone mold for holding teeth during X-rays.
Apical patency was confirmed and working length was established 1mm shorter than the length at which a K-file #10/.02 (MANI INC., Utsunomiya, Tochigi, Japan) was visualized at the apical foramen.
The initial root canal preparation was performed using BioRace system (FKG Dentaire, La Chaux-de-Fonds, Switzerland) according to manufacturers recomendations. Speed of 600rpm and 1 Ncm torque was used with X-smart motor (Dentsply Maillefer, Ballaigues, Switzerland).
Apical preparation was performed with K-file #50/.02 according to “morphometric and anatomical studies of the root canal system” [15]. During instrumentation canals were irrigated with 2ml of 5,25% sodium hypochlorite (NaOCl) solution after each instrument and recapitulated with #15/02. Following instrumentation, the smear layer of each canal was removed by applying 5ml of 17% ethylenediaminetetraacetic acid (EDTA) for 3minutes, followed by rinsing with 10ml distilled water and then dried with paper points. The canals were obturated with gutta-percha and resin-based root canal sealer (ADSEAL, META BIOMED CO., LTD., Cheongju-si, Chungbuk, Korea) using lateral condensation technique. Zinc oxide eugenol was placed as a temporary filling.
Teeth were radiographed after obturation from two directions (mesiodistal and buccolingual) to check the quality of obturation at a fixed distance of 5cm (Fig.4). Teeth were stored in 100% humidity at 37 oC for 14 days to allow the sealer to set. After incubation period the teeth were randomly divided into two groups, 10 teeth in each.
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Fig. 4: Post-obturation X-rays in buccolingual and mesiodistal directions.
Root canal retreatment Group 1
D-race (FKG Dentaire, La Chaux-de-Fonds, Switzerland) was used as follows:
a drop of solvent was applied, Eucalyptus oil (PPH CERKAMED, Stalowa Wola, Poland) for 1min followed by initial penetration with DR1 #30/.1 with 1000rpm speed and 1.5Ncm torque to about 1-2mm.
DR2 was inserted into the canal with 600rpm speed and 1Ncm torque. The instrument was not forced inside, but rather was let to work inside the canal with slight pressure. The blade was regularly retracted and cleaned until full working length was reached. Retreatment was considered finished when there was no root canal filling material exiting the canal anymore after
instrumentation [18].
Each instrument was discarded after one use to avoid instrument separations. Root canals were irrigated with 2ml of 5,25% sodium hypochlorite (NaOCl) solution each time the instrument was retracted and the orifice was cleaned from all root canal filling material with gauze.
Page 18
Group 2
The procedure described previously (Group 1) was performed. Then XP-endo Finisher R (FKG Dentaire, La Chaux-de-Fonds, Switzerland) was used as follows: the instrument was cooled and working length was measured. Access cavity was filled with solvent. Instrument was inserted into the canal to full forking length and was let to work for 30 seconds, then retracted and cleaned (also the orifice was cleaned with gauze). Second time access cavity was irrigated 2ml with 5,25% sodium hypochlorite (NaOCl) solution and access cavity was filled with irrigant, instrument was again inserted to full working length and let to work for 30 seconds. Procedure was again repeated, instrument was retracted and cleaned and so was the orifice. Last step was done by filling access cavity with 17% ethylenediaminetetraacetic acid (EDTA), instrument was inserted again to full working length and let to work for 15 seconds. Retreatment was finished by rinsing with 10ml distilled water and then dried with paper points [19].
Each instrument was discarded after single use to avoid instrument separations.
Radiographic evaluation
After removal of the root canal filling material, each tooth was radiographed from mesiodistal and buccolingual direction at a fixed distance of 5cm using the same silicone mold as mentioned earlier. Each radiograph was very closely evaluated with the obturated version and retreated version of same tooth to find common anatomical landmarks. Each radiograph was then divided into three parts (cervical, middle and apical), based on the common anatomical landmarks, with software Paint (Version 1607 (OSBuild 14393.693), Microsoft Windows). The procedure was repeated on all radiographs.
In order to calculate the percentage of remaining root canal filling material inside root canals all pictures were measured in square pixels with software Paint (to confirm identical size of pictures). The area of root canal filling material was calculated using Sketchandcalc software [20].
The areas of each third were identified through the difference in radiopacity, outlined and measured with the software. Then the areas of remaining root canal filling material in each third were
identified, outlined and measured. Total canal areas and corresponding remaining filling material areas were calculated by adding the values obtained from the three thirds.
Page 19 The area percentages of remaining filling material were calculated by dividing the filling material covered areas to the designated canal areas and multiplying by 100 [Fig. 5].
Fig. 5: Calculation of remnants of root canal filling material.
Statistical analysis
For the statistical analysis t-tests were performed with a significance level set at 5%, by same operator as the experimental part using Social Science Statistics software [21]. The mean and standard deviation was calculated with Advanced Scientific Calculator software [22] [Table 6-a,b].
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RESULTS
All teeth had significant amount of root canal filling material remnants, better results were observed in Group 2, significant difference. The differences were checked for each part (cervical, middle and apical) and for each X-ray in percentage and in statistical significance [Table 1, 2]. In Table 1 there is shown how much remnants were observed between these two systems. The use of XP-endo Finisher R showed a significant difference in cleaning ability in every part (cervical, middle and apical) and increased cleaning ability (25.19%) [Table 1].
D-race D-race + XP-endo
Finisher R.
Bucco-lingual Mesio-distal Bucco-lingual Mesio-distal
Cervical 47.95% 35.48% 24.77% 16.79%
Medial 37.90% 32.34% 13.01% 10.81%
Apical 36.73% 43.02% 11.13% 5.75%
Total 38.90% 13.71%
Table 1: Shown from each X-ray direction and each part how much root canal filling material
remnants were left in canals.
Also the statistical significance between the two groups in each part of the canals were also recorded, as well as in total [Table 2]. In the second group with XP-endo Finisher R there is a noticeable decrease of the standard deviation, showing its efficiency as a finishing file.
Page 21
Cervical Medial Apical Total
D-race 41.7%(19.9)A 35.1% (22.6)A 39.9% (29.6)A 38.9% (24.1)A
D-race + XP-endo Finisher R
20.8% (17.8)A 11.9% (18.1)A 8.4% (16.2)A 13.7% (17.9)A
Table 5: Area of residual filling material (means +/- standard deviations (SD)) of each third of
canal after instrumentation. In each column values followed by the same capital letters represent statistically significant (p<0.05) differences between the two groups.
The percentage of the canal area containing radiopaque residue. Calculated for each third of the canal from buccolingual and mesiodistal projections, also presented the median, minimum and maximum values of the different parts [Fig. 6- a, b].
Fig. 6-a: Group 1, median, minimum and maximum values of each third and total of canal, after
instrumentation.
Page 22
Fig. 6-b: Group 2, median, minimum and maximum values of each third and total of canal, after
instrumentation.
Representative radiographs for “good” cases with group 1 [Fig. 7-a] and “poor” cases with group 1
[Fig. 7-b], also a representative radiograph for a common case for group 2 [Fig. 7-c].
Fig. 7-a: Post-retreatment by group 1. “Good”.
Page 23
Figure 7-b: Post-retreatment by group 1. “Poor”.
Page 24
DISCUSSION
The aim of this research was to evaluate the efficiency of MaxWire® alloy file in removing root canal filling material after retreatment with endodontic retreatment instruments, which is essential for good retreatment prognosis even though it has not been proven that it is a necessity to remove completely all old root canal filling material. It seems, however, essential to remove as much as possible in order to get to the infected parts that are hidden inside the canal [8].
This research was carried out with straight root canals and with minimal defects, therefore
conclusions cannot be related to teeth with curved root canals or teeth with big defects, but can give a better understanding in general regarding endodontic retreatment.
An important aspect needs to be addressed regarding the shape of the root canals: 30% of
mandibular distal canals are “oval-shaped” 5mm from apex [23], which may have had a big impact on our results - up 38.90% material remnants. It was observed that D-race had not the same ability to follow the canal morphology, making a straight path towards the apex and not “scout” for remnants as XP-endo Finisher R. This instrument follow the morphology more precisely, due to its ability to work in mixed phases (martensitic-phase/austentic-phase), allows it to scout for remnants and become very flexible inside root canal. The results comparing to another study may vary depending on the canal morphology of the teeth used. Study conducted by Silva EJNL et al. (2015) used only oval-shape root canals and no statistical difference between WaveOne system and
ProTaper Retreatment System [8]. Their results may have been different if the canals were only “non-oval” or mixed pool of canal types. In this research there were not paid any attention to the shape of the canals and the total pool was mixed.
There is a general trend showing apical preparations to be similar in different systems but better in middle and cervical parts if compared to D-race system in this research which may be because of many reasons [10, 11, 24]. Some of them may have been: use of solvent as eucalyptol-oil in all retreatment procedures which may dissolve gutta-percha inside the canal and cause it to stick to the canal walls and increments [24]. Also D-race system did not “scout” the morphology in search of root canal filling remnants but relies on an additional system/file to finish preparation.
The master apical file in the teeth used for this study was #50 according to “morphometric and anatomical studies of the root canal system” [15]. This means that finishing with anything less than #50 will mean almost 100% failure in removing 100% of root canal filling material in the apical part therefore the use of hand files (also any treatment files) are of still great use today for
Page 25 not have as good efficiency as one might hope, even after discussing about solvents and not being enough flexible to follow anatomy to the apical part, it comes down mostly to the overall size of the file itself. It is impossible for a type of instrument as D-race to clean properly by itself because of its small size, however, the XP-endo Finisher R is made from a completely different technology which allows it to adapt and “scout” as previously mentioned the canal in search for root canal filling remnants, all thanks to its mixed phase technology which are exclusive for FKG MaxWire® alloys (martensitic-phase of 20 oC and austentic-phase of 35 oC).
The best is clearly to combine retreatment files in order to get the best possible retreatment. The XP-endo Finisher R was in a sufficient manner adding the effect of a second file, by removing a great part of the remaining root canal filling material by mechanical movement. Even in here a drop of solvent was used, but in this case because the file “explores the canal” and becomes extra
flexible during treatment (initiated by heat) it most likely was helping with having softened gutta-percha.
The way of evaluation for success of retreatment, in this study, was by performing X-rays which were performed from 2 angles 90o from each other. This should obtain a good overall picture of how much is left in canal and how much is removed in theory, but it would only work 100% in cases on a quadrat root with four corners in 90o. In this case, root canal anatomy in general is more rounded. It takes many different shapes which are not related to 90 degrees corners, this will cause a lot of clean areas to “hide behind” the gutta-percha filled wall. Ideally would be to use a three-dimensional visualization of the root to see all these “hidden” corners.
Another effect on the results regarding radiography may be due to different ways of dividing the canal thirds (cervical, middle and apical). Some researchers did not specify how they divided the root canal thirds [9, 11] while one divided strictly by thirds by the length (equal thirds) [8]. Comparing researchers with different methodology regarding radiography might also give some changes and different results not necessarily mean that any on them were wrong. In this study the canals were divided into thirds (cervical, middle and apical) according to identical anatomical landmarks (as close to equal thirds as possible). This will minimize any errors in X-ray angulation at the picture taking moment (because of the common anatomical landmarks, the area was kept the same).
Because of these “failures” we can see big deviations from the norm where the results randomly have very big difference from each other in the same group. In the figure, there are presented the strong deviations due to some errors or anatomical obstacles [Fig. 6-a,b].
Page 26 It is easy to visualize the differences in success rate of removing root canal filling material with only D-race without additional help. This might be because of all the previous mentioned reasons but also a factor could be that the D-race system is not as reliable in hands of diverse skilled operators as XP-endo Finisher R which will guarantee a better result. It is possible to see in the pictures examples of how a final retreatment would look in a “good” with D-race and a “poor” with D-race, also a “normal” case with XP-endo Finisher R (all according the results that were found in this research) [Fig. 7a,b,c].
Unfortunately, one last limitation to this research was that it was carried out in-vitro which can come very close to in-vivo researchers, but will never simulate 100% a clinical situation. This might have affected the results in all stages of this research (all necessary preventive measures were taken) even though they will be minimal they have to be acknowledged. Further study is definitely
required, especially in-vivo.
ACKNOWLEDGEMENT
The material support by FKG Dentaire (La Chaux-de-Fonds, Switzerland) for this study and Linas Vaitkus in helping with X-rays for the research are gratefully acknowledged.
CONFLICT OF INTERESTS
The author denies any conflict of interest related to this research.
CONCLUSION
1. Removing root canal filling material using D-race retreatment instruments were not efficient on its own, gross amount of radiopaque residue was evident in canals.
2. Supplementary use of MaxWire® alloy file XP-endo Finisher R significantly reduced the amount of radiopaque residue.
PRACTICAL RECOMMENDATIONS
If D-race system is being used, the additional use of XP-endo Finisher R could effectively improve the root canal filling material elimination.
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ETHICAL STATEMENT
There is no ethical issue regarding this study due to randomly selected teeth with no possibility in identifying to whom they belong.
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