Abstract:

The use of gutta-percha as a standard obturation material has made little changes in the obturation technique. Resilon has been developed as an alternative to gutta-percha (GP), but its advantages over gutta-percha remain controversial. The aim of this study was to prepare a new root canal filling material from thermoplastic polyurethane (TPU) based on polycarbonate (PCA), with inorganic filler particles (50% wt), calcium carbonate (CaCo 3), zinc oxide, calcium hydroxide and barium sulfate. The prepared material (CaCo3/ TPU) characterized by Differential Scanning Calorimeter (DSC) and Infra Red Spectroscopy (FTIR) and were subjected to some mechanical (Hardness and Tensile strength) and physical tests (Radiopacity and Water sorption and solubility). For biocompatibility test, the prepared material was implanted in rabbits subcutaneously. The root canal sealer was prepared from TPU with (10% wt) fillers and subjected to film thickness and flowability test according to ANSI/ADA No.57. Push out test and dye penetration test were also performed to evaluate bonding strength and apical microleakage. 

The results of DSC, FTIR showed that the prepared material is definitely PCA/TPU with homogenous incorporation of the fillers. The hardness and tensile strength were consistent with ADA specification no.12.and ISO 527–2:1993. The solubility was 0.0035 g/mm3, while the water sorption was 0.0047 g/mm3, and this conforms with the ISO standard (4049:1988). Regarding the radiopacity test, it showed that the prepared material exhibits radiopacity equivalent to 6 mm of aluminium step wedge, which complying with the ANSI/ADA No.78. The Biocompatibility test demonstrated a significantly lower mean number of inflammatory cells in the CaCo3/TPU composite in comparison to GP, particularly after 21 days. Comparing the flowability and film thickness of the prepared sealer with ZOE sealer as a control, it was noticed that the prepared sealer is within the desirable limits proposed by ANSI/ADA No.57. The Push out test revealed higher bond strength of CaCo3/ TPU (18.15Mpa) when compared with both GP - AH plus and TPU -TPU sealers. 

Finally, the microleakage of CaCo3/TPU without sealer showed significantly less microleakage when compared with GP-AH plus sealer and TPU-TPU sealer. In conclusion, the prepared material exhibits better mechanical, physical and bonding properties. It appears to have better compatibility than GP, particularly at 21 days, and has potential to be used safely as a durable root canal filling material.

Keywords:

Nano-Calcium Carbonate Polyurethane (CaCO3/TPU), Root Canal Obturation, Biocompatibility, Microleakage, Bond Strength

Reference List:

1. Agrawal CM and Ray RB (2001). Biodegradable polymeric scaffolds for musculoskeletal tissue engineering. Journal of Biomedical Materials Research; 55:141-150. 

2. Ahlberg KMF, Assavanop P and Tay WM (1995). A comparison of the apical dye penetration patterns shown by methylene blue and Indian ink in root filled teeth. Int Endod J; 28:30-34. 

3. Akihiro Y, Taizo W, Toshiki I, Maritaka K, Kazuhiko N, Tatsushi K and Hiroshi N (2005). Mechanical properties of newly developed soft type gutta-percha point. J Jap Endod Assoc; 26:190-195. 

4. Akman M, Akman S, Derinbaya O and Bellic S (2010). Evaluation of Gaps or Voids Occurring in Roots, Filled with Three Different Sealers, Eur J Dent.; 4:101-109. 

5. Al- Ani Y H and Al-Huwaizi HF (2011). Push out bond strength of different obturation systems (An in vitro study). J Bagh College of Dentistry; 23(3): 37-43. 

6. American national standers institute/American association specification, ANSI\ADA (1999). dental No. 12 for denture base polymer, Chicago: council on dental material and devices. 

7. American National Standard/American Dental Association, ANSI/ADA Specification No.78. (2006) Dental Obturating Cones Modified adoption of ISO 6877-1:1995; Dental Obturating Points. 

8. American National Standard/American Dental Association, ANSI/ADA Specification No.57 (2006). Endodontic sealing materials. Modified adoption of ISO 6876:2000 Dental root canal sealing materials.

9. American Society for Testing and Materials, ASTM E1269-95 (2000). Standard test method for determining specific heat capacity by differential scanning calorimetry.

10. Atkins P and De Paula J(2006). Physical Chemistry, 8th ed. Oxford University Press: Oxford, UK. 

11. Azadi N, Fallahdoost A, Mehrvarzfar P, Rakhshan H, and Rakhshan V (2012). A four-week solubility assessment of AH-26 and four new root canal sealers. Dent Res J 9(1): 31–35. 

12. Barbizam J V, Trope M, Tanomaru-Filho M Teixeira CN, and Teixeira FB (2011). Bond strength of different endodontic sealers to dentin: push-out test. J Appl Oral Sci; 19 :6. 

13. Barros V, Rosa A, Beloti A and Chierice G (2010).In vivo biocompatibility of three different chemical compositions of Ricinus communis polyurethane. Mater Res; 67A: 235–239. 

14. Behrend GD, Cutler CW, and Gutmann JL (1996). An in-vitro study of smear layer removal and microbial leakage along root canal fillings. Int Endod J;29:99. 

15. Bergenholtz G, Horsted-bindslev P and Reit C (2010). Text book of endodontology.2nd ed. Wiley-Blackwell publishing. Ch:12:194 

16. Beriat NC, Ertan A, Cehreli ZC, Gulsahi K (2009). Time-dependent conversion of a methacrylate- based sealer polymerized with different light-curing units. J Endod; 35: 110–2. 

17. Beyer-Olsen EM, Orstavik D (1981). Radiopacity of root canal sealers. Oral Surg Oral Med Oral Pathol; 51:320-8. 

18. Bodanez A, Munhoz EA, Bernardineli N, Capelozza AL, Moraesi and Bramante CM (2010). Radiographic Analysis of Root Canal Fillings: Influence of Two Sealers on the Perception of Voids. Braz Dent J; 21(2): 142-147. 

19. Bouillaguet S, Shaw L, Barthelemy J, Krejci I, Wataha JC (2008). Long-term sealing ability of pulp canal sealer, AH-Plus, GuttaFlow and epiphany. Int Endod J; 41:219–26.

To see the full list of References for this PhD Thesis, please click to view or download the PDF version,