Measurement and Comparison of Volumetric Shrinkage of
Various Sealers Registered by a Video Imaging Technique Device
Shahab Rezai and Hossein Sobhani Tutor: Majid Ebrahimi
2 ABSTRACT
Obturation ability of root canal treatment materials are one of the factors that affect the prognosis of root canal treatment with essence of complete closure of the root canal. Cold lateral condensation is one of the most common techniques used for endodontic therapy which sealer acts as sealing and bonding agent between dentin and gutta-percha.
The aims of the study are to examine and compare the volumetric shrinkage of the three most common endodontic sealers in Sweden categorized by their chemical composition. Our hypothesis is that there is no difference between these sealers regarding shrinkage.
Epoxy-amine resin based sealer (AH Plus Jet), zinc oxide eugenol based sealer (Tubli-Seal EWT) and calcium hydroxide based (Apexit Plus) have been compared in this study, which are categorized into three major different chemical compositions. A video imaging technique device, AcuVol, has been used to register volumetric shrinkage of these sealers.
Registration of sealers volumetric shrinkage by AcuVol occurred two times for each sealer during a 48 hr period.
Mean volumetric shrinkage after 48 hr determined to 6.43 % for epoxy-amine resin based sealer (AH Plus Jet), 6.72 % for zinc oxide eugenol based sealer (Tubli-Seal EWT) and 1.63 % for calcium hydroxide based sealer (Apexit Plus).
Based on this study, it could not be possible to recommend a sealer in terms of volume shrinkage perspective and determine which sealer is best. There are other parameters of sealer than shrinkage that can affect adequately root canal obturation we should consider.
3 INTRODUCTION
The amount of endodontic treated teeth with periapical periodontitis has increased over the last three decades (Skudutyte-Rysstad and Eriksen, 2006) and according to reports from the Swedish Social Insurance Agency in 2015, about 4 % of Sweden's population has had root canal treatment (Försäkringskassan, 2015; Statistiska Centralbyrån, 2016).
The aim of root canal treatment is to eliminate bacterial infection and prevent bacterial penetration along the root filling into the apex region and eliminate any remaining organisms, by filling the void space and complete closure of the root canal, that could otherwise be filled with nutritious liquid and provide fertile ground for microorganism (Singh et al., 2015; Ørstavik and Pitt Ford, 1998).
The outcome of root canal therapy is dependent on operator and influence of various factors (Bergenholtz et al., 2010). In a study by Sjögren and co-workers in 1990, the overall success was assessed to be 91 %, however, these teeth were treated by undergraduate students under supervision of specialists (Sjögren et al., 1990). Information about the prognosis for endodontic treatment in general dentistry is very limited.
Factors that can lead to the failure of root canal treatment are remaining bacteria in the canal at the time of root canal sealing, poor obturation quality of root canal, over- under extended obturation, coronal leakage, untreated root canals, poor access preparation and fracture of instruments (Tabassum and Khan, 2016). Inadequate root canal obturation that causes leakage around the root canal filling material is the most common reason of not achieving optimal root canal therapy (Song et al., 2011).
Cold lateral condensation is one of the most common techniques used for root canal therapy where sealer acts as the sealing and bonding agent between dentin, core material gutta-percha and fill the accessory canals, thus obtain optimal obturation (KonjhodzicPrcic et al., 2015; Salz et al., 2009).
Some characteristics can affect sealers optimal function such as tissue compatibility, dimensional stability, radiopacity, antibacterial action, adhesion to dentin wall, working time, setting time, solubility and discolorations (ISO, 2001).
During polymerization of sealers some shrinkage appears due to rearrangement of the
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intermolecular bonds between molecules that takes less space, which in turn, results in lower density, micro-leakage, and clinical failure (Hammad et al., 2008).
Sealers are classified according to their chemical composition including epoxy amine resin based, zinc oxide eugenol based, calcium hydroxide based, silicon based and glass ionomer (Singh et al., 2015; Bergenholtz et al., 2010).
Among other factors, shrinkage of sealers may cause poor root canal obturation, which can lead to failure of root canal treatment. Thereupon, the aims of the study, are to examine and compare the volumetric shrinkage of the three most common endodontic sealers in Sweden categorized by their chemical composition, AH Plus Jet, Tubli-Seal EWT and Apexit Plus (SBU, 2010).
MATERIALS & METHODS
In this study, we used three common sealer types categorized by their chemical composition that was provided as base and activator in a tube together with a mixing tip.
AH Plus Jet ™ is a two-component root canal sealer based on epoxy-amine resin, kindly provided by DENTSPLY DeTrey GmbH, Germany. Its setting time is 24 hr at 37 °C. In solid condition, it gives less tissue irritation and has shown a low cytotoxicity (KonjhodzicPrcic et al., 2015). Epoxy-amine resin based sealer releases small amounts of formaldehyde which can cause reactions in sensitized individuals (Koch et al., 2001).
Tubli-Seal ™ EWT is a two-component root canal sealer based on zinc oxide eugenol, kindly provided by Kerr Corporation 28200 Wick Road Romulus, MI 48174 USA. Its setting time is less than 2 hr at 37 °C. Eugenol can cause allergic reactions (Syed et al., 2015).
Apexit Plus is a two-component root canal sealer based on calcium hydroxide, kindly provided by Ivoclar Vivadent AG FL-9494 schaan/Liechtenstein. Its setting time is between 3-5 hr at 37 °C but in very dry canals can take more than 10 hr. Outside the mouth, Apexit Plus may remain soft for several days, depending on the ambient humidity. It does not contain any pharmaceutical substance such as corticoids, antibiotics or formaldehyde according to the manufacture.
In order to measure and compare the volumetric shrinkage of the three most common endodontic sealers categorized by their chemical composition, we used the video imaging
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technique device, AcuVol manufactured by BISCO Inc. (Schaumburg, IL, USA). The AcuVol is designed to allow non-contact visual analysis of volume changes in small volume samples.
The maximum sample size is 4 mm in diameter, 6 mm horizontal x 5 mm vertical. Analysis was done in volume units and percent changes, in volume. The results of the analysis were provided in graphs and values that will automatically be saved in the computer (Fig. 3).
Maximum test duration in a single continuous test sample was 48 hr. AcuVol has a rotational mode to register volumetric shrinkage, which enables us to record shrinkage from different surfaces. In rotational mode, the pedestal and sample are stepped through one complete revolution and images are taken at each step position. Sealers were applied above the pedestal, which were rotated in front of a camera inside the AcuVol. Volumetric shrinkage of each sealer was measured and registered every 15 minutes during 48 hr. All registered data were presented both in graph and table form.
As control, a dimensionally stable specimen (round plastic ball) was used to ensure that the AcuVol machine is working correctly and eliminating measurement errors. Volumetric shrinkage of control subject during 48 hr was noticed.
The temperatures in the root canal is higher than the inside of AcuVol. Higher temperature reduces viscosity of sealers which affect their setting time (Lacey et al., 2006; Camilleri, 2014).
In order to compensate for temperature differences, we decided to measure volumetric shrinkage of each sealer for a longer time i.e. during 48 hr. In this experiment, each sealer was measured two times during a 48 hr period of time.
Ethical considerations
The Ethics Forum at the Department of Odontology at Umea University determine adequate ethical incorporated in this thesis. Ethical issues that may arise in connection with this study can be that the results may influence the choice of sealer used in dentistry. This study should avoid, as far as sponsorship from companies, to not let the result be affected by it. Potential benefits of the project might be to discover the most appropriate sealer from shrinking perspective and to increase the probability of successful root canal treatments in the future.
Collected data and results have been saved as computer files. As the project does not involve biological patient/animal data or patient data, there are no obstacles to the establishment of a data file.
6 Literature search
In this study some useful scientific articles were found in PubMed by searching key words like:
“root canal sealers”, “sealer shrinkage”, “sealing properties”, “dental materials”, “microleakage in endodontic”, “AH Plus”, “Tubli-Seal”, “Apexit Plus”, “AcuVol”. Most of the articles that were studied before starting the experiment had been published within the last 10 years.
RESULTS
This study showed and compared shrinkage of the three most common endodontic sealers categorized by their chemical composition.
As a control, we registered shrinkage of a dimensionally stable specimen by AcuVol during 48 hr before the measurement of the sealers volumetric shrinkage. The registered shrinkage was 0.3 % after both 24 hr and 48 hr. This may not affect results in broad terms however, but it should be taken into consideration in the interpretation of results.
Measurement of epoxy-amine resin based sealer (AH Plus Jet), represent shrinkage 5.76 % and 6.13 % after 24 hr, 6.29 % and 6.56 % after 48 hr. Zinc oxide eugenol based sealer (Tubli-Seal EWT), represent shrinkage 5.80 % and 6.29 % after 24 hr, 6.36 % and 7.07 % after 48 hr.
Calcium hydroxide based sealer (Apexit Plus), represent shrinkage 1.11 % and 1.93 % after 24 hr, 1.18 % and 2.07 % after 48 hr.
Volumetric shrinkage values of the three sealers are presented in table 1. The most amount of volumetric change occurred during the first 24 hr which is the time recommended according to the instructions for use, however, volumetric change shows up to 48 hr (Fig. 1).
Mean volumetric shrinkage determined to 5.95 % after 24 hr, 6.43 % after 48 hr for epoxy- amine resin based sealer (AH Plus Jet), 6.05 % after 24 hr, 6.72 % after 48 hr for zinc oxide eugenol based sealer (Tubli-Seal EWT) and 1.52 % after 24 hr, 1.63 % after 48 hr for calcium hydroxide based sealer (Apexit Plus) (Table 1).
The results of the study show values that are almost similar between epoxy-amine resin based sealer (AH Plus Jet) and zinc oxide eugenol based sealer (Tubli-Seal EWT). Apexit Plus shows less shrinkage (Fig. 2).
7 DISCUSSION
The quality of the root canal filling is one of the factors that affect the prognosis (Singh et al., 2015). Inadequate root canal obturation is the most common cause of not achieving optimal root canal therapy, that leads to a negative prognosis by leakage around the root canal filling material which increases the risk of access of bacteria to the apex and the progress or maintenance of periapical injury (Song et al., 2011). The aim of root canal therapy is eliminating bacterial infection, preventing bacterial penetration along the root filling into the apex region, eliminating any remaining organisms by filling the void space, and complete closure of the root canal that could otherwise be filled with nutritious liquid and provide fertile ground for microorganism. (Singh et al., 2015; Ørstavik and Pitt Ford, 1998).
Shrinkage of sealer enable inadequate root canal obturation and leakage, which leads to failure in root canal therapy thus affecting the prognosis (Singh et al., 2015).
To find error measurement of AcuVol, the experiment started by measuring the dimensionally stable specimen during 48 hr.
All sealer volumetric shrinkage measurement was done in duplicate during 48 hr by the video imaging technique device, AcuVol. Mean volumetric shrinkage determined to 5.95 % after 24 hr, 6.43 % after 48 hr for epoxy-amine resin based sealer (AH Plus Jet), 6.05 % after 24 hr, 6.72 % after 48 hr for zinc oxide eugenol based sealer (Tubli-Seal EWT) and 1.52 % after 24 hr, 1.63 % after 48 hr for calcium hydroxide based sealer (Apexit Plus) (Fig. 2).
The hypothesis that there is no difference between these sealers regarding shrinkage is broadly correct due to the results of the study, that shows values that are almost similar between epoxy- amine resin based sealer (AH Plus Jet) and zinc oxide eugenol based sealer (Tubli-Seal EWT).
Apexit Plus shows less shrinkage. Apexit Plus was not completely solidified after 48 hr and this may probably have affected its results. According to the manufacture, the setting time of Apexit Plus in the root canal is dependent upon the availability of moisture, and decrease with high temperature and humidity. Outside the mouth, Apexit Plus may remain soft for several days, depending on the ambient humidity. Apexit Plus has two components calcium hydroxide and salicylate that need water to completely solidified.
By using AcuVol, it is not possible to create a moist milieu required for Apexit Plus to solidify
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and consequently, measurement of accurate volumetric shrinkage of sealer can be inaccurate.
Optimal root filling technique requires dehydration of the root canal before applying root filling material, so there is no humidity which Apexit Plus needs to completely solidify but according to the manufacture, the material begins to set at the apex, as dentin is thinnest in this region and the apical foramen admits additional moisture. Also, the setting reaction of Apexit Plus can progress very quickly in canals, which have been inadequately dried.
The temperature in a root canal is higher than inside of AcuVol. Higher temperature reduces viscosity of sealers which affect their setting time (Lacey et al., 2006; Camilleri, 2014). In order to compensate for temperature differences, we decided to measure volumetric shrinkage after 24 hr and 48 hr. Longer test time could not be performed as regards maximum possible test time with AcuVol is 48 hr.
In conclusion, we were able to measure shrinkage of above-mentioned sealer. Results show no difference in shrinkage between the tested sealers. Apexit Plus need a moist milieu in order to set completely, however the root canal usually is dehydrated before obturation. How this affect the prognosis of teeth treated with Apexit Plus is unknown and yet to be investigated. Based on this study, it couldn’t be possible to recommend a sealer in terms of volume shrinkage perspective and determine which sealer is best. There are other parameters of sealer than shrinkage that can affect adequately root canal obturation we should consider.
ACKNOWLEDGMENTS
We would like to wholeheartedly thank all individuals who have helped us to make this project in the best thinkable way. A special heartfelt thanks to our tutor Majid Ebrahimi who has dedicated both his time and knowledge to management of this study with his amazing experience. Anders Berglund for his valued advice during this project. We are appreciative to BISCO-, DENTSPLY-, KERR- and Ivoclar Vivadent Company for kindly providing us with material for our study.
9 REFERENCES
Bergenholtz G, Hörsted-Bindslev P, Reit C (2010). Textbook of endodontology. Chichester, West Sussex: Blackwell Pub, pp. 202, 302.
Camilleri J (2014). Sealers and Warm Gutta-percha Obturation Techniques. J Endod 41(1):72–
80.
Forsakringskassan. 2016. Tandvård. https://www.forsakringskassan.se/statistik/statistik_och_
analys2/ovrigaersatt/tandvard (Retrieved 2016-05-15).
Hammad, M., Qualtrough, A. and Silikas, N. (2008). Extended Setting Shrinkage Behavior of Endodontic Sealers. J Endod 34(1):90-93.
ISO 6876:2001. Dental root canal sealing materials. International Organisation for Standardisation, Geneva, Switzerland 2001.
Koch, M., Wunstel, E. and Stein, G. (2001). Formaldehyde Release from Ground Root Canal Sealer In Vitro. J Endod 27(6):396-97.
KonjhodzicPrcic, A., Jakupovic, S., Brankovic, L. and Vukovic, A. (2015). Evaluation of Biocompatibility of Root Canal Sealers on L929 Fibroblasts with Multiscan EX Spectrophotometer. Acta Inform Med23(3):135-37.
Lacey, S., Pitt Ford, T., Yuan, X., Sherriff, M. and Watson, T. (2006). The effect of temperature on viscosity of root canal sealers. Int Endod J 39(11):860-66.
Salz, U., Poppe, D., Sbicego, S. and Roulet, J. (2009). Sealing properties of a new root canal sealer. Int Endod J 42(12):1084–89.
SBU. 2010. Endodontisk diagnostik och behandling. http://www.tandlakartidningen.se/media /3104368/sbu%20rotfyllning. pdf (Retrieved 2016-05-15).
Singh, H., Markan, S., Kaur, M. and Gupta, G. (2015). “Endodontic Sealers”: Current Concepts and Comparative Analysis. Dent Open J 2(1):32-37.
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Sjögren U, Hagglund B, Sundqvist G, Wing K. (1990). Factors affecting the long-term results of endodontic treatment. J Endod 16(10):498-504.
Skudutyte-Rysstad, R. and Eriksen, H. (2006). Endodontic status amongst 35-year-old Oslo citizens and changes over a 30-year period. Int Endod J 39(8):637-42.
Song, M., Kim, H., Lee, W. and Kim, E. (2011). Analysis of the Cause of Failure in Nonsurgical Endodontic Treatment by Microscopic Inspection during Endodontic Microsurgery. J Endod 37(11):1516–19.
Statistiska Centralbyrån 2016. Befolkningsstatistik. http://www.scb.se/sv_/Hitta-statistik/
Statistik-efter-amne/Befolkning/Befolkningens-sammansattning/Befolkningsstatistik (Retrieved 2016-05-15).
Syed, M., Chopra, R. and Sachdev, V. (2015). Allergic Reactions to Dental Materials- A Systematic Review. J Clin Diagn Res 9(10): ZE04-09.
Tabassum, S. and Khan, F. (2016). Failure of endodontic treatment: The usual suspects. Eur J Dent 10(1):144-47.
Ørstavik D, Pitt Ford TR. (1998). Essential Endodontology: Prevention and Treatment of Apical Periodontitis. Blackwell Scientific; 1998. pp. 242-277.
11 Table 1.
Volumetric shrinkage measurement of sealers after 24 hr and 48 hr respectively mean value for each.
* Shows the lowest shrinkage value, however complete setting could not be achieved after 48 hr.
Volumetric shrinkage (%)
24 hr 48 hr
AH Plus Jet
5.76 6.29
6.13 6.56
Tubli-Seal EWT
5.80 6.36
6.29 7.07
Apexit Plus *
1.11 1.18
1.93 2.07
12 Figure 1.
Volumetric shrinkage of three sealers in percent during 48 hr.
AH Plus Jet,Tubli-Seal EWT,Apexit Plus.
0 1 2 3 4 5 6 7 8
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
VO LU M ET RI C SH RI N KA G E IN P ER CE N T (% )
TIME IN HOURS
SHRINKAGE
13 Figure 2.
Mean volumetric shrinkage of sealers in percent.
AH Plus Jet,Tubli-Seal EWT,Apexit Plus.
24 hours 48 hours
AH Plus Jet 5,95 6,43
Tubli-Seal EWT 6,05 6,72
Apexit Plus 1,52 1,63
5,95
6,43 6,05
6,72
1,52 1,63
0 1 2 3 4 5 6 7
MEAN VOLUMETRIC SHRINKAGE IN PERCENT (%)
MEAN SHRINKAGE
14 Figure 3.
Sealer placed on pedestal inside of AcuVol showing shrinkage during 48 hr.
The blue line shows the sealers baseline, the green line shows sealers state after 48 hr.
