Evaluation of the radiopacity of different root canal sealers Melahat Gorduysus, DDS,a and Nihal Avcu, DDS,b Ankara, Turkey HACETTEPE UNIVERSITY
Objective: The aims of this study were to compare the radiopacity of 8 root canal sealers relative to gutta-percha and dentin in standard discs and to evaluate the effect of these sealers on the radiopacity of root canal fillings in simulated canals. Study design: Radiographs were taken of 1-mm-thick specimens of 8 root canal sealers (Diaket, Endion, MTA, Endofil, Roeko Seal, Sealite, AH26, AH Plus) and gutta-percha, a 1-mm-thick human tooth slice, and aluminum stepwedge. Simulated canals were used to evaluate the effect of the sealer on radiopacity of the root fillings. After enlargement of the simulated canals with ProTaper instrument, root canals were filled with these 8 sealers alone and with single ProTaper gutta-percha cone. Radiographs of all filled simulated canals were taken with an aluminum stepwedge. Results: All the sealers demonstrated greater radiopacity than dentin (0.7940 mm Al) (P ⬍ .001). AH Plus showed the highest radiopacity in the standard disc group (Group 1) (8.9881 mm Al) (P ⬍ .001), and in the sealer group in simulated canals (Group 2) (9.2100 mm Al) (P ⬍ .001). In the sealer plus gutta-percha group in simulated canals (Group 3), Sealite plus gutta-percha showed greater radiopacity (8.4460 mm Al) (P ⬍ .001). Conclusion: Whether the opacity of the sealers alone is more or less than 3 mm Al, their radiopacity is increased when they are used in combination with gutta-percha, because of its higher radiopacity. However, when sealers are used in conjunction with gutta-percha, they can affect the radiopacity of the root canal filling according to their type and thickness. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:e135-e140)
Root canal sealers should have sufficient radiopacity to allow clinicians to make a clear distinction between the materials and the surrounding anatomic structures1,2 and to evaluate the quality of the root fillings.3 The International Organization for Standardization (ISO)4 687672001 established that the radiopacity of the root canal sealing materials should not be less than that equivalent to 3 mm of aluminum. Although it has been shown that gutta-percha cone brands all exceed the radiopacity requirement,5 some materials do not meet this requirement.2 The international standards for the radiodensity of root canal sealing materials have been determined using dental occlusal films.4 To test the radiopacity of root canal sealers, it is recommended that samples of the test material should be prepared in standard discs.4 As a result, the radiopacity of root canal sealers has been established in most studies using the standard disc.6,7 Higginbotham8 was the first researcher to assess the radiopacity of various endodontic sealers and cone materials used for canal obturation. Eliasson and Haasken9 a
Associate Professor, Department of Endodontics, Hacettepe University, Faculty of Dentistry, Ankara, Turkey. b Associate Professor, Department of Oral Diagnosis and Radiology, Hacettepe University, Faculty of Dentistry, Ankara, Turkey. Received for publication Jan 27, 2009; returned for revision Apr 4, 2009; accepted for publication Apr 7, 2009. 1079-2104/$ - see front matter © 2009 Published by Mosby, Inc. doi:10.1016/j.tripleo.2009.04.016
were the first to establish a standardized method of radiopacity measurements for dental materials with an aluminum stepwedge to allow the transformation of readings of light to an equivalent thickness of aluminum. The aluminum stepwedge is chosen as the standard for measuring radiopacity because it allows comparison of a specific sample thickness of aluminum stepwedge under typical radiographic conditions.6 However, clinical conditions differ from standard in vitro conditions. In in vivo conditions, soft tissue, bone, dentin, sealer, and gutta-percha cones constitute the overall density value of the root canal filling.10 In the latest study, it was reported that the type and the thickness of root canal sealers can influence the radiopacity of the root fillings in simulated canals.10 The highly radiopaque sealers may mask imperfections in the filling, especially when they are used in conjunction with gutta-percha.11 Therefore, the aim of this study was to compare the radiopacity of 8 root canal sealers in standard discs and in simulated canals to evaluate the effect of these sealers on the radiopacity of root canal fillings in simulated canals. MATERIALS AND METHODS Eight root canal sealers were evaluated in this study. Material types, commercial names, and manufacturers are listed in Table I. e135
OOOOE September 2009
Gorduysus and Ace
Table I. Root canal sealers and manufacturers used in this study Product
Diaket Endion ProRoot MTA Endofil Roeko Seal Sealite AH26 AH Plus Gutta-percha
A polyvinyl resin Glass ionomer-based sealer Portland cement Zinc oxide–eugenol-based A polydimethylsiloxane-based material Zinc oxide–based sealer Epoxy resin Epoxy resin-based Zinc oxide
ESPE Seefeld/Oberbay Germany Voco Cuxhaven, Germany Dentsply Tulsa Dental, Tulsa, OK Dentsply-Latin America, Petropolis, Brazil Roeko, Langenau, Germany Pierre Rolland, Marignac, Cedex, France Dentsply De Trey GmbH, Konstaz, Germany Dentsply De Trey GmbH, Konstaz, Germany ProTaper, Dentsply Maillefer, Ballaigues, Switzerland
Preparation of materials in standard disc Seven acrylic plates containing 9 wells measuring 1 mm in thickness and 4 mm in diameter were prepared. Sealers were mixed according to the manufacturers’ recommendations, and each material was placed into the wells (Group 1). After covering with a cellophane sheet, a glass plate was used to ensure that the top surface was smooth. Each plate with the sealers was stored in a moist chamber (incubator) at 37°C until completely set. ProTaper gutta-percha cones (Dentsply, Maillefer, Switzerland) were warmed and adapted into the remaining wells as controls. A longitudinal section of dentin (1-mm thick) was cut from freshly extracted human molar teeth using an 1800-rpm speed saw (ISOMET 4000 linear precision saw; Witrz-Buehler GmbH, Dusseldorf, Germany). It was kept in tap water until use. The same tooth slice was used for each specimen. The acrylic plate with specimens, an aluminum stepwedge, and tooth slice were placed on the same occlusal film (Kodak Ultra-speed, Stuttgart, Germany). The radiographs were obtained using a dental x-ray machine (Gendex GX, Lake Zurich, IL, USA) at 70 kVp, 10 mA and 0.35 seconds with a focus-film distance of 30 cm.1,12 All films were processed in an automatic developing machine (XR 24 Pro, Dürr Dental, Bietigheim, Germany). The aluminum stepwedge was made of 99.5% pure aluminum from 1 mm to 12 mm, in uniform steps of 1 mm each. Images of each step on the aluminum stepwedge, the samples, and 1-mm-thick specimens of dentin were read with a transmission densitometer (DT 1105, RY Parry LTD, Newbury Berkshire, England). Three measurements were obtained for each specimen, aluminum stepwedge, and tooth slice, and the means of these readings were calculated. Preparation of materials in simulated root canals One hundred twenty-six simulated root canals (63 in sealer group; 63 in sealer plus gutta-percha group) were prepared in transparent acrylic blocks (Endo-TrainingBlock .02 Taper, Dentsply). The canals were instrumented
by ProTaper (Dentsply) rotary instruments. Each canal was prepared with size F3 finishing file. All test materials were mixed according to manufacturers’ instructions. In each group (n ⫽ 7), the sealer was placed into the simulated canals by using lentulo. Seven transparent acrylic blocks were filled with single F3 size ProTaper guttapercha cones (Dentsply) as controls. In the sealer plus gutta-percha group, all the sealers were placed in the canals with single F3 size ProTaper gutta-percha cones. The specimens with sealer alone (Group 2) and aluminum stepwedge with gutta-percha (control) were placed on the same occlusal film (Kodak Ultra-speed), and specimens with gutta-percha plus sealer (Group 3) and aluminum stepwedge with guttapercha (control) were placed together on another occlusal film. The radiographs were obtained using a dental x-ray machine (Gendex GX) at 70 kVp, 10 mA, and 0.35 second with a focus-film distance of 30 cm.1,12 All films were processed in an automatic developing machine (XR 24 Pro, Dürr Dental). The same conditions were applied for all films. The optical density (OD) of the radiographic image of each step on the aluminum stepwedge in the samples was read with a transmission densitometer (DT 1105, RY Parry LTD, Newbury Berkshire, England). Three measurements were obtained for each specimen, and the means of these readings were calculated. In simulated canals, the measurements were made at the 11.6-mm level of the canal, where the diameter is approximately 1 mm with digital calibration by a compass. To provide the same condition in Groups 2 and 3, measurements were made at that same level (11.6 mm) for each specimen for using grid paper (Figs. 1 and 2) and their radiopacities were evaluated by densitometer. The OD data for the aluminum steps were entered into a computer (Table II), and the best possible fit was used for curves of aluminum OD (Fig. 3). Statistical analysis Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) 11.5 software
OOOOE Volume 108, Number 3
Gorduysus and Ace e137
Table II. Aluminum thickness and density of stepwedge Thickness of aluminum, mm
Optical density, optical density units
0 (base ⫹ fog) 1 2 3 4 5 6 7 8 9 10 11 12
Aluminium thickness and density of stepwedge Thickness of aluminium (mm)
Fig. 1. Radiographic image of the aluminum stepwedge, molar slice, simulated canal filled with gutta-percha, and specimens of each tested material. Measurements were made at the same level (11.6 mm) as with the simulated canal specimen for using grid paper (grid paper is seen on the simulated canal).
1.902 1.513 1.268 1.100 0.995 0.918 0.854 0.809 0.773 0.741 0.717 0.705 0.693
14 12 10 8 6 4 2 0 0.650
Fig. 3. Calibration curve for aluminum stepwedge.
possible multiple comparisons controlling for type I error.
Fig. 2. Radiographic image of the aluminum stepwedge, and simulated canal filled with the tested material. Measurements were made at the same level (11.6 mm) for each specimen for using grid paper (grid paper is seen on specimen 2).
(SPSS Inc., Chicago, IL). Shapiro Wilk test was used to test the distribution normality of the continuous data. Data were expressed as median (interquartile range [IQR]). The differences among materials or setup were evaluated by Kruskal-Wallis test. When the P value from the Kruskal-Wallis test statistics indicated statistical significance, Mann-Whitney U test was used to determine stepwise differences between groups. A P value less than .05 was considered as statistically significant. The Bonferroni correction was applied for all
RESULTS Table II shows aluminum thickness and density of the steps of the aluminum stepwedge. The millimeter equivalents of aluminum for each material are given in Table III. Standard disc group (Group 1) All sealers in Group 1 were found to demonstrate greater opacity than dentin (0.7940 mm Al) (P ⬍ .001). Diaket, mineral trioxide aggregate (MTA), and AH26 demonstrated a radiopacity lower than 3 mm Al (1.2969, 2.9081, and 2.2817, respectively). Statistical differences in radiopacity were determined between Endion and AH26 compared with gutta-percha (P ⬍ .001); between Diaket compared to Endion, MTA, Roeko Seal, and AH Plus (P ⬍ .001); between Endion and AH26 (P ⬍ .001); between Endofill and AH26 compared with AH Plus (P ⬍ .001); and between Roeko Seal and Sealite compared to AH26 (P ⬍ .001). AH Plus showed the highest radiopacity (8.9881 mm
OOOOE September 2009
Gorduysus and Ace
Table III. Equivalent aluminum thickness of filling materials Aluminum equivalent, mm Specimen 1 2 3 4 5 6 7 8 9 10
Gutta-percha Diaket Endion MTA Endofil Roeko Seal Sealite AH26 AH Plus Dentin
5.2370 ⫾ 0.00787 1.2969 ⫾ 0.00212 6.0979 ⫾ 0.00713 2.9081 ⫾ 0.00363 3.1114 ⫾ 0.00553 5.1576 ⫾ 0.00724 3.9680 ⫾ 0.01023 2.2817 ⫾ 0.00838 8.9881 ⫾ 0.00917 0.7940 0.00469
5.2370 ⫾ 0.00622 2.5520 ⫾ 0.00100 6.8310 ⫾ 0.00603 6.9412 ⫾ 0.00106 7.5398 ⫾ 0.00186 6.6088 ⫾ 0.00514 5.2340 ⫾ 0.00289 3.7954 ⫾ 0.00411 9.2100 ⫾ 0.00483 —
5.0448 ⫾ 0.00089 5.4140 ⫾ 0.00351 6.2470 ⫾ 0.00337 6.2910 ⫾ 0.00238 4.2070 ⫾ 0.00532 8.2860 ⫾ 0.00580 8.4460 ⫾ 0.00580 4.0940 ⫾ 0.00173 5.0972 ⫾ 0.00157 —
Al) followed by Endion, gutta-percha, Roeko Seal, Sealite, Endofill, MTA, AH26, and Diaket (6.0979, 5.2370, 5.1576, 3.9680, 3.1114, 2.9080, 2.2817, and 1.2969 mm Al, respectively) (P ⬍ .001). Simulated canals with sealer (Group 2) AH Plus showed the highest radiopacity (9.2100 mm Al) followed by Endofill, MTA, Endion, Roeko Seal, Sealite, AH26, and Diaket (7.5398, 6.9412, 6.8310, 6.6088, 5.2340, 3.7954 and 2.5520 mm Al, respectively). Except for Diaket, all materials showed a radiopacity of at least 3 mm Al. Although there was no statistically significant difference between gutta-percha and Sealite, a significant difference was determined between gutta-percha and the remainder of the materials (P ⬍ .001). Simulated canals with sealer plus gutta-percha (Group 3) Statistically significant differences were determined between all tested materials (P ⬍ .001). Radiopacity of gutta-percha was 5.0448 mm Al in simulated canals and 5.2370 mm Al in standard disc. AH26 and Endofill reduced the radiopacity of gutta-percha (4.0940, 4.2070 mm Al, respectively). Sealite plus gutta-percha showed greater radiopacity (8.4460) followed by Roeko Seal, MTA, Endion, Diaket, AH Plus, gutta-percha, Endofill, and AH26 (8.2860, 6.2910, 6.2470, 5.4140, 5.0972, 5.0448, 4.2070, and 4.0940 mm Al, respectively) (P ⬍ .001). DISCUSSION The sealer plays a vital role in root canal fillings. The sealer fills all the space the gutta-percha is unable to fill because of its physical limitations. Sealer serves as a filler for canal irregularities and minor discrepancies between the root canal wall and core filling material. Sealers are often expressed through lateral or accessory canals and can assist in microbial control should there
be microorganisms left on the root canal walls or in the tubules.13 When the sealer extrudes from the root apex to the anatomic structures such as bone and tooth, gutta-percha and the sealer can be differentiated depending on the degree of their radiopacity. Additionally, radiopacity of root canal sealers has been of particular significance for the evaluation of the quality of endodontic treatment as well as being helpful in the assessment of possible voids in the obturation.10 However, a material advertised as radiopaque according to the ISO standards may not be sufficiently radiopaque under clinical conditions.10 Conventional periapical radiography is the most commonly used method for the evaluation of the technical quality of the obturated canal. Wenzel et al.14 evaluated the radiopacity of dental filling materials using conventional intraoral radiographic film and 2 digital systems with the purpose of investigating the possibility of discrimination solely on the basis of radiopacity of materials. The digital systems were determined to be less reliable than film in this discrimination. The highly radiopaque sealers may detract from the quality of the compaction of the solid core material and give a false sense of obturation radiodensity.13 Gambarini et al.11 also reported that sealing materials that are too radiopaque may mask imperfections in the filling, especially when used in conjunction with gutta-percha. Sealite, a zinc oxide– based sealer, contains zinc oxide, silver powder, and diiodothymol. In our study, whereas the radiopacity of Sealite was less than that of gutta-percha in Groups 1 and 2, Sealite showed high radiopacity when used in combination with gutta-percha (8.4460 mm Al). AH Plus, an epoxy resin, contains zirconium oxide and iron oxide, which contribute to its greater radiopacity. Tanomaru-Filbo et al.7 reported that the radiopacities of AH Plus and Roeko Seal specimen in 1 mm thickness of standard disc were 9.8 mm Al and 5.7 mm
OOOOE Volume 108, Number 3
Al, respectively. In our study, AH Plus demonstrated higher radiopacity in Group 1 (8.9881 mm Al) and Group 2 (9.2100 mm Al), but in Group 3 it showed the radiopacity level as that of gutta-percha (5.0972). AH Plus masked the present radiopacity when used in combination with gutta-percha. Roeko Seal, a polydimethylsiloxane-based material, contains zirconium dioxide, which accounts for its radiopacity. In standard discs, radiopacity was 5.1576 mm Al. This result is similar to that reported by Tanomaru-Filbo et al.7 In the present study, Roeko Seal demonstrated higher radiopacity than gutta-percha in Group 2 (6.6088 mm Al), and in Group 3, it highly increased the radiopacity of the root canal filling (8.2860 mm Al). Previous studies indicated that all gutta-percha cone brands exceeded the minimal radiopacity requirement.5 In our study, radiopacity of gutta-percha was determined as 5.2370 mm Al in standard disc and 5.0448 mm Al in simulated canals. Gutta-percha cones contain radiopacifier agents like barium sulphate and zinc oxide. Some root canal filling materials appeared to be insufficiently radiopaque in clinical use.2 Diaket, a polyvinyl resin– based sealer, contains zinc oxide and bismuth phosphate. In our study, Diaket showed less radiopacity in both Group 1 and Group 2 (1.2969, 2.5520 mm Al, respectively). This level is even less than the 3 mm Al cut-off according to ISO standardization. When used with gutta-percha, Diaket slightly increased the radiopacity level of the root canal filing over that of gutta-percha alone (5.4140 mm Al.). Baskı Akdeniz et al.10 studied simulated canals and emphasized that because all simulated canals were instrumented and filled using standard procedures, the thickness of the sealers should be homogeneous around the gutta-percha cones. They also showed that the thickness of the root canal sealer around the core filling material also has an effect on the radiopacity of the sealer, and consequently on the overall radiopacity of the filling. The international standards for the radiodensity of root canal sealing materials have been determined using dental occlusal films.4 There have been numerous investigations about the radiopacity of different root canal sealing materials.6,7,10 Variations in aluminum equivalence values for dentin and sealers in other studies could be explained by differences in the aluminum alloy of the stepwedge, exposure time, kVp, mAs, focal film distance, film speed, imaging technique, and developing process.15,16 In our study, the differences in aluminum equivalence values of the materials may be explained by these conditions. Furthermore, in our study, the radiopacity
Gorduysus and Ace e139
level of all sealers in Group 2 were greater than in Group 1, which can be due to the radiographic images of the simulated canals. The technique used to evaluate the radiopacity of dental materials compared specific thickness of materials to aluminum stepwedges under controlled radiographic conditions. The radiopacity of a dental material specimen is usually expressed in terms of equivalent aluminum thickness (in millimeters) using a reference calibration curve. The methodology applied in this study is similar to that used in most studies investigating the radiopacity of dental materials.6,7,17 Expression of radiopacity in the equivalent aluminum thickness allows comparison between the radiopacity of the tested materials and that of the surrounding dental structures (dentin and bone). Moreover, it allows comparison between the results found in several studies, with some limitations due to the pureness of the aluminum used in the stepwedge and the different radiopacity values found for the dentin and bone. The molecular structure and the thickness of a material have a major effect on the radiopacity.18 The results obtained in the present study demonstrate that AH Plus and Endion demonstrated greater radiopacity than the other materials evaluated in Group 1 and Group 2. It is reported that a sealing material that is too opaque may mask imperfections in the filling, especially when used in combination with gutta-percha.11 Endion is essentially a glass ionomer sealer that contains Ca-Al-F-silicate-glass and polyacrylic acid. Endion showed higher radiopacity than gutta-percha in Group 1 and Group 2 (6.0979 and 6.8310, respectively). In Group 3, its radiopacity level was 6.2470 mm Al. Although Endofil showed high radiopacity (7.5398) in Group 2, when used with gutta- percha, radiopacity of the root canal filling decreased (4.2070 mm Al). Endofil, a zinc oxide– eugenol-based sealer, contains barium sulphate, zinc oxide, and bismuth subcarbonate. In our study, the difference in opacity levels may be because of the existence/absence of a hydrogen bond between zinc oxide and eugenol. This issue will require further research. AH26, an epoxy resin, contains bismuth oxide, silver, and titanium dioxide, which contributes to its radiopacity. In our study, radiopacity of AH26 was 2.2817 mm Al in standard disc. Our finding is inconsistent with those of Bodrumlu et al.6 AH26 depressed the radiopacity of gutta-percha. Radiopacity of the root canal filling decreased below the radiopacity of guttapercha (4.0940 mm Al). MTA is an endodontic material that was first used as a root end filling material, but it has also been used as an alternative in several clinical procedures, such as
OOOOE September 2009
Gorduysus and Ace
capping of pulp tissue, root end closure, repair of furcal perforations, and for orthograde filling of the entire root canal.19,20 In the current study, MTA was used as a root canal sealer. MTA (ProRoot, Dentsply, Tulsa Dental, Tulsa, OK) contains Portland cement, dehydrated calcium sulfate (gypsum), and bismuth oxide as the radiopacifier.21 In the present study, MTA showed less radiopacity, even less than 3 mm Al, in Group 1 (2.9081), whereas in Group 2 its level was 6.9412 mm Al. In Group 3, radiopacity level of the root canal filling was slightly decreased (6.2910 mm Al). In conclusion, radiopacity of all the sealers was greater than that of dentin. Whether the opacity of sealers is more or less than 3 mm Al, their radiopacity is increased when used in combination with guttapercha, because of its higher radiopacity. Use of sealers in combination with gutta-percha can affect the radiopacity of root canal fillings. REFERENCES 1. Beyer-Olsen EM, Ørstavik D. Radiopacity of root canal sealers. Oral Surg Oral Med Oral Pathol 1981;51:320-8. 2. Katz A, Kaffe I, Littner M, Tagger M, Tamse A. Densitometric measurement of radiopacity of gutta-percha cones and root dentin. J Endod 1990;16:211-3. 3. Goldman M, Simmonds S, Rush R. The usefulness of dyepenetration studies reexamined. Oral Surg Oral Med Oral Pathol 1989;67:327-32. 4. International Organization for Standardization (ISO) 6876:2001, Geneva, Switzerland. Dental Root Canal Sealing Materials 2001. 5. Kaffe I, Littner MM, Tagger M, Tamse A. Is the radiopacity standard for gutta-percha sufficient for clinical use? J Endod 1983;99:58-9. 6. Bodrumlu E, Sumer P, Gungor K. Radiopacity of a new root canal sealer, epiphany. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:e59-e61. 7. Tanomaru-Filbo M, Gouveia Jorge E, GuerreiroTanomaru M, Gonçalves M. Radiopacity evaluation of new root canal filling materials by digitalization of images. J Endod 2007;33:249-51. 8. Higginbotham TL. A comparative study of the physical properties of five commonly used root canal sealers. Oral Surg Oral Med Oral Pathol 1967;24:89-101.
9. Eliasson ST, Haasken B. Radiopacity of impression materials. Oral Surg Oral Med Oral Pathol 1979;47:485-91. 10. Baskı Akdeniz BG, Eyübog˘lu TF, S¸en BH, Erdilek N. The effect of three different sealers on the radiopacity of root filling in simulated canals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:138-41. 11. Gambarini G, Testarelli L, Pongione G, Gerosa R, Gagliani M. Radiographic and rheological properties of a new endodontic sealer. Aust Endod J 2006;32:31-4. 12. Van Aken J. Optimum conditions for intraoral roentgenograms. Oral Surg Oral Med Oral Pathol 1969;21:475-91. 13. Gutmann JL, Witherspoon DE. Obturation of the cleaned and shaped root canal system. In: Cohen S, Burns RC, editors. Pathways of the pulp. St. Louis: Mosby; 1998. p. 258-361. 14. Wenzel A, Hintze H, Horsted-Bindslev P. Discrimination between restorative dental materials by their radiopacity measured in film radiograph and digital images. J Forensic Odontostomatol 1998;16:8-13. 15. Laghios CD, Benson BW, Gutmann JL, Cutler CW. Comparative radiopacity of tetracalcium phosphate and other root-end filling materials. Int Endod J 2000;33:311-5. 16. el-Mowafy OM, Benmergui C. Radiopacity of resin-based inlay luting cements. Oper Dent 1994;19:11-5. 17. Devito KL, Ortega AI, Haiter-Neto F. Radiopacity of calcium hydroxide cement compared with human tooth structure. J Appl Oral Sci 2004;12(4):290-3. 18. Prevost AP, Forest D, Tanguay R, DeGrandmont P. Radiopacity of glass ionomer dental materials. Oral Surg Oral Med Oral Pathol 1990;70:231-5. 19. Torabinejad M, Chivan N. Clinical applications of mineral trioxide aggregate. J Endod 1999;25:197-205. 20. Schmitt D, Lee J, Bogen G. Multifaceted use of ProRootTM MTA root canal repair material. Am Acad Pediatr Dent 2001;23: 326-30. 21. Funteas UR, Wallace JA, Fochtman EW. A comparative analysis of mineral trioxide aggregate and Portland cement. Aust Endod J 2003;29:43-4.
Reprint requests: Melahat Gorduysus, DDS Hacettepe University, Faculty of Dentistry Department of Endodontics 06600 Sıhhiye-Ankara/Turkey [email protected]