0099-2399/90/1608-0365/$02.00/0 JOURNAL OF ENDODONTICS Copyright 9 1990 by The American Association of Endodontists

Printed in U.S.A. VOL. 16, NO. 8, AUGUST 1990

Evaluation of Diagnostic Radiopaque Contrast Materials Used with Calcium Hydroxide Tayfun Ala~;am, DDS, Guliz GorgiJI, DDS, and H,ima Omfirlu, DDS

An evaluation of three different radiopaque materials used in combination with calcium hydroxide powder for diagnostic contrast was made. Diatrizoate meglumine (65%) and iothalamate meglumine (60%) compared favorably with barium sulfate (35%). Since barium sulfate has demonstrated problems by altering the manipulative properties of calcium hydroxide as well as demonstrating a residual radiopacity, there may be advantages to the use of resorbable diatrizoate or iothalamate compounds as alternatives. These soluble iodine compounds also make possible an excellent aqueous medium in which to mix calcium hydroxide.

All of the calcium hydroxide pastes described above lack radiopacity and therefore cannot be visualized on radiographs. Radiopaque materials are added to the paste to provide radiopacity, thus aiding in determining the location of the calcium hydroxide paste in the root canal system. Lateral and accessory root canals, resorptive areas, fractures of the root, development of the apex, and other important diagnostic structures may become visible by inclusion of a radiopaquing agent in the paste. Certain salts of heavy metals, such as barium and bismuth, and compounds containing iodine or bromine are opaque to X-rays. It is possible to visualize their location in tissue by means of radiographs. Insoluble bismuth salts were used in roentgen examination of the gastrointestinal tract before barium sulfate was introduced in 1910. Bismuth subcarbonate was preferred over bismuth subnitrate because of its lower toxicity. Today, this compound is still used in the formulas of some root canal sealers such as AH26. In modem medical practice, barium sulfate is used instead of bismuth salts because it is inexpensive and it is not toxic even in high dosages. Soluble barium salts are extremely toxic materials so that in clinical practice the insoluble barium sulfate is preferred. Dental BaSO4 is found in various Ca(OH)2 preparations in the ratio of 1:7 by weight. When Ca(OH)2 is extruded beyond the apex, theBaSO4 can obscure the apex and is not readily resorbed over time. Webber et al. (6) suggest a reduction of the usual ratio of BaSOa:Ca(OH)2 to 1:8 in order to reduce the problem of residual radiopacity at the root apex. However, in a case reported by him, radiopaque remnants of the paste were still obscuring the apex of a treated tooth after 21 months. This made a radiographic interpretation of osseous healing more difficult. This residual radiopacity is due to the inability of the body to resorb relatively insoluble BaSO4. Only 0.02 g of BaSO4 can be dissolved in 100 ml of water. As an alternative to BaSO4, there are more soluble radiopaque agents available, the majority of which are iodine-containing compounds. One such radiopaque agent used in dentistry is an aqueous solution of 10% iodine and 20% potassium iodide. However, this solution if mixed with Ca(OH)2 would probably be extremely irritating if extruded beyond the apex. Peach (8) observed many soluble iodine compounds and suggested that the diatrizoate compounds were the least toxic of this type of radiopaquing media. The diatrizoates are organic iodine-containing molecules having solubilities ranging from 60 to 89 g per 100 ml of water. Most are stable solutions with high radiodensity. Diatrizoates have been in-

Calcium hydroxide is used in various clinical situations. Its role in endodontics has been expanded by its inclusion in the formulas of many dentin-lining materials, pulp capping agents, root canal filling materials, and root canal sealers (16). Calcium hydroxide provides the advantages of easy preparation by the clinician and a biological influence by raising the tissue pH in the local environment of resorptive defects (5). Resorption of the material occurs should it be extruded beyond the root canal system (3). The ability of calcium hydroxide to denature proteins, rendering them less toxic, may also assist in improving endodontic reparative processes (l). Calcium hydroxide is a formless, thin, granular powder with strong basic properties and a density of 2.1. It can dissolve only slightly in water and is insoluble in alcohol (7). Most clinicians prefer to use pure Ca(OHh as they believe that the ingredients of commercial preparations may retard or delay the reparative processes they seek. In addition, they can easily make a paste of any consistency desired by mixing the pure powder with a suitable liquid. Many liquids have been suggested for mixing with Ca(OH)2 to obtain a paste desirable for use in root canal treatment. Distilled water, isotonic water, isotonic saline, dental anesthetic (preferably without a vasoconstrictor), glycerin, camphorated monochlorophenol, camphorated parachlorophenol, and Ringer's solution are but some of these materials. A germicide is not needed as a vehicle, due to the antibacterial effect of calcium hydroxide. Therefore, a desirable vehicle for calcium hydroxide could be one that is tissue compatible and nonirritating to the periodontal tissues.

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jected in dental patients in order to aid in the diagnosis o f periapical lesions as well as to determine pathways of anesthetic injections (9). Smith and Woods (9) mixed Ca(OH)2 and a diatrizoate compound and used this solution in apexification procedures. They suggested that this solution prevents obscuring of the apical region on radiographs taken during and after apexification. Iothalamates are also radiopaque organic iodine compounds. They are soluble in water. Solutions of this agent are clear or colorless to pale yellow in hue and slightly viscous in mature. They have been used in diagnostic tests such a urography, angiography, venography, and some other radiological tests and computerized tomographs because of their high radiopacity. In systemic use, the iothalamate salts are less toxic than the diatrizoate salts (7). This study was undertaken to evaluate the radiopaque properties of these two different organic iodine diagnostic radiopaque contrast materials when mixed with calcium hydroxide powder by comparing them with the more commonly used barium sulfate and with pure calcium hydroxide. MATERIALS AND METHODS The radiopaque values of the pastes consisting of pure calcium hydroxide powder used in endodontic therapy were studied. Also studied were three different X-ray contrast materials: barium sulfate, diatrizoate meglumine, and iothalamate meglumine in different concentrations mixed with calcium hydroxide in paste preparations containing various concentrations of distilled water. In preliminary investigations it was found that the ideal mixture of the paste was made by mixing 4.8 g of Ca(OH)2 powder with 4 ml of distilled water. Preparations of calcium hydroxide with barium sulfate included concentrations of 5 to 35%, calcium hydroxide preparations with diatrizoate meglumine included concentrations of 15 to 65%, calcium hydroxide preparations with iothalamate meglumine included concentrations of 15 to 60%. These mixtures and concentrations are shown in Tables 1 to 3, respectively.

Six samples of each mixture and each concentration were used for study. The test object was made from commercially pure aluminum with base measurements of 5 x 30 mm. There was a total of six steps of 0.5-, 1.5-, 2.0-, 2.5-, and 3-mm thickness, and two dentin samples with base measurements of 7.5 x 6 mm, 5.5 x 5.5 mm, and 2.5 m m in thickness (Fig. 1). For the measurements of the materials, conditions for exposure were standardized at 70 kV, 7 mA, 0.5 s, and a filmto-focus distance of 40 cm. These conditions were based on the Australian Standard (no. 1278-1982). TABLE 2. Diatrizoate meglumine concentrations used with Ca(OH)= % (vol)

Diatrizoate Meglumine (ml)

Pure Water (ml)

15 20 30 40 45 50 65

O.92 1.232 1.84 2.464 2.768 3.08 4.00

3.08 2.768 2.16 1.536 1.232 0.92 0.00

TABLE 3. Iothalamate meglumine concentrations used with Ca(OH)= % (vol)

Iothalamate Meglumine (ml)

Pure Water (ml)

15 20 30 40 45 50 60

1.00 1.328 2.00 2.648 3.00 3.32 4.00

3.O0 2.672 2.00 1.352 1.00 0.68 0.00

Preparation of the Samples The prepared pastes were placed into Teflon ring molds of 10 m m in diameter and of a uniform thickness of 2.0 mm.

TABLE 1. Amount of Ca(OH)= and BaSO4 in the samples of Ca(OH)=-BaSO4 pastes Ratio of Ratio of Ratio of Amount of Amount of BaSO4:Ca(OH)2 BaSO4 Ca(OH)2 BaSO4 in Ca(OH)2in in the Powder the Paste the Paste (%) (g) (g) (%-wt/wt)* (%-wt/wt)* 5:95 10:90 15:85 20:80 25:75 30:70 35:65

0.24 0.50 0.75 1.00 1.25 1.50 1.75

4.46 4.30 4.05 3.80 3.55 3.30 3.05

2.73 5.68 8.62 11.4 14.2 17.1 19.9

51.8 48.9 46.0 43.2 40.3 37.5 34.7

* When we made a paste with 4.8 g of powder (BaSO4 + Ca(OH)2) and 4 ml of pure water, the percentage ratio of BaSO4 or Ca(OH)2 in this paste.

r

9

/ L 84

9

FIG 1. Top, Aluminum step wedge and dentin samples; lower right, iothalamate meglumine (60%) + Ca(OH)2; and lower left, pure Ca(OH)2.

X-Ray Contrast Medias with Ca(OH)=

Vol. 16, No. 8, August 1990

Agfa-Gevaert N.V. B-25 l0 (Mortsel Antwerpen, Belgium) periapical film size 1'/4 x 15/8 inches (3 x 4 cm) was used. All films were developed under standardized conditions using Agfa-Gevaert G 150 ( 1:3, 2 min) developer and Agfa-Gevaert G 334 (1:4, 3 min) fixative. The temperature was kept at 25~ The density values of the samples being examined, each step of the aluminum step wedge, and the dentin controls were measured by a transmission densitometer DT 1105 (R. Y. Parry Ltd., Newburry Berkshire, England). In order to be sure that the measurements were taken under the same conditions and to document the results of the overall study, the mean values and standard deviations of densities reported for the steps of the aluminum step wedge and dentin samples were calculated (10). The coefficient of variation was determined to be CV= s/x. 100. RESULTS The densities measured for each step across many films were similar (Table 4). The mean values and standard deviations of the densitometric values of the groups are documented in Table 5. Comparing the results, it was found that corresponding concentrations of diatrizoate meglumine and iothalamate meglumine compounds showed similar radiopaque values. Sixty-five percent diatrizoate meglumine + Ca(OH)2 and 60% iothalamate meglumine + Ca(OH)2 showed values comparable to 35% to 30% BaSO4 + Ca(OH)> Kalsin which is a commercial preparation showed a radiopaque value that was TABLE 4. Radiopacity value (radiodensity) of the steps of the aluminum step wedge and the two dentin samples Material

Aluminum (step no.)

Dentin (sample no.)

No.

X

% CV

1 2 3 4 5 6 1 2

815.611 847.1176 941.33 1043.667 1184.444 1362.22 1302.88 1218.77

12.07 11.48 10.49 11.17 11.44 12.12 12.31 12.72

367

similar to 30% diatrizoate meglumine + Ca(OH)2 or 30% iothalamate meglumine + Ca(OH)2.

DISCUSSION Several investigators compared the radiopacity of specimens with the steps of an aluminum wedge on radiographs of the specimens adjacent to the wedge. In some cases this was a visual comparison (11-13). In other investigations densitometry was used. Either radiopacity was expressed as an aluminum equivalent (13, 14) or linear attenuation coefficients were derived (15, 16). In our investigation, in order to standardize the densitometric results we used an aluminum step wedge. In order to achieve improved manipulation of the material as well as better residual radiopaque characteristics in tissue, this study compared different materials with mixed with Ca(OH)2 other than BaSO4. These were diagnostic agents used to make X-ray contrast medium in order to examine organ functions, to determine the blood volume and hemopoietic function, and to make diagnostic tests (7). Organic compounds have been used in addition to inorganic substances in X-ray contrast medium. The toxic and allergic potentials of inorganic iodine compounds has led to the use of organic iodine compounds in diagnostic procedures (7). Iodine containing diatrizoate and iothalamate salts are solutions of diatrizoic and iothalamic acid in water. The addition of meglumine hydroxide enhances their solubility. They are used in medical radiography by injection because they do not have any toxic or allergic effect. These media are highly advantageous in that they are sterile, have prolonged shelf lives, are inexpensive, and are readily available through hospital pharmacies (9). These advantages led to the choice of these agents for mixing with Ca(OH)2 and possible use in endodontics. It is found that both the diatrizoate and the iothalamate compounds become a more viscous mass when mixed with Ca(OH)2 compared with the manipulative properties of pastes made of pure water, Ca(OH)2, and BaSO4. For this reason, it is suggested that it may be necessary to evaluate the viscosity of these pastes and at the same time determine the flow, film

TABLE 5. Mean values and standard deviations of the radiodensities of the different concentrations of the diagnostic radiopaque contrast materials used with Ca(OH)= Diatrizoate Meglumine + Ca(OH)2 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 60% 65%

Iothalamate Meglumine + Ca(OH)2

1235 _+ 65.71 1211 ___38.22

1233 _+ 58.41 1178 _+ 45.94

1080 _-+20.66

1066 _+ 29.78

1013 --- 32.15 981 --- 21.39 971 _+ 21.39

1014 1000 986 969

BaSO4 + Ca(OH)2

Ca(OH)2

Kalsin

1481

1019

1473 _+ 54.17 1410__ 51.11 1349 -+ 71.24 1254 _+ 73.72 1099 __+46.34 988 -- 9.64 977 + 15.18

_+ 30.27 --- 60.63 -+ 14.58 -+ 6.33

968 ___11.50

368

Journal of Endodontics

A l a g a m et al.

thickness, setting time, dimensional stability, and shelf lives of these pastes in further studies. In a report by Smith and Woods (9), a diatrizoate-Ca(OH)2 paste was shown to be more radiopaque than a BaSO4:Ca(OH)2 paste (1:4) when placed into the root canal of an extracted maxillary central incisor (9). In the results reported here, 65% diatrizoate meglumine-Ca(OH)2 and 60% iothalamate meglumine-Ca(OH)2 showed a radiopacity similar to a paste containing 35% BaSO4. However, the dissolving ability of BaSO, in water is very low and in order to reach a radiopacity similar to that of iothalamate meglumine and diatrizoate meglumine using 35% or more BaSO4 creates problems of residual opacity when placed in tissue. Iothalamate meglumine was used as an alternative material to diatrizoate compounds that have been previously reported in the literature. Both compounds have been widely used in medicine as contrast medium materials. The difference in their systemic toxicities is very small. Clinical reports indicate iothalamates are preferable to diatrizoates (17, 18). As should be recognized, there is no X-ray contrast material that does not have risk factors associated with its use. Because of this, iothalamate meglumine which has better properties was included in this study. Research suggests that homogenous distribution of radiopaque agents in pastes is an important problem. During the preparation of the pastes, BaSO4 was added to the pure water and then Ca(OH)2 was added to this mixture to assure homogenity. A question arises concerning the compatibility of these organic iodine-containing substances with Ca(OH)> Literature dealing with this problem reveals that Ca(OH)2 could only take iodine molecules from the compound if the temperature was high enough. The conditions and temperature in which these materials were used or are likely to be used was considered to be suitable from the point of their compatibility. In this study, some deviations in the paste consistency were observed when powders of Ca(OH)2 and BaSO4 were mixed with pure water. It was thought that as the water affinity of BaSO4 and Ca(OH)2 powders in different concentrations of these powders differed, the amount of water which was sufficient to make the ideal paste would also be different. In order to make an ideal paste consistency, a further study must be done after which the water affinity of each powder should be determined and the concentrations prepared.

It is suggested that diatrizoate and iothalamate compounds can be used as alternatives to BaSO4. The advantages are being able to be stocked in the refrigerator of the dentist for long periods of time, easier manipulation with a medium with which to mix Ca(OH)2 powder, and a medium having radiopaquing features more suitable for purposes of endodontic practice. We thank Mrs. Jan McSherry and O~juzhan Sungur for their assistance in translation of this article to English. Drs. Ala(;am, GOrg01, and s are affiliated with the Department of Endodontics, Faculty of Dentistry, Gazi University, Ankara, Turkey.

References 1. Dylewski JJ. Apical closure of non-vital teeth. Oral Surg 1971 ;32:82-9. 2. Fisher FS. The effect of a calcium hydroxide-water paste on microorganisms in carious dentine. Br Dent J 1972;133:19-21. 3. Nicholls E. Endodontics. 3rd ed. Bristol: Wright, 1984:271-283. 4. Steward GG. Calcium hydroxide induced root healing. J Am Dent Assoc 1975;90:793-800. 5. Tronstad L, Andreasen JO, Hasselgren G, et al. pH changes in dental tissues after root canal filling with calcium hydroxide. J Endodon 1981 ;7:1-17. 6. Webber RT, Schwiebert KA, Cathey GM. A technique for placement of calcium hydroxide in the root canal system. J Am Dent Assoc 1981 ;103:41721. 7. Swinyard EA. Diagnostic drugs. In: Oson A, Chose GD, Gennaro AR, et al, eds. Remington's pharmaceutical sciences. 16th ed. Easton, PA:Mack Publishing Co., 1980:1212-24. 8. Peach MJ. The pharmacological basis of therapeutics. New York: MacMillian Publishing Co., Inc., 1975. 9. Smith NG, Woods S. Organic iodine: a substitute for BaSO4 in apexification procedures. J Endodon 1983;9:153-5. 10. Walpale RE. Introduction to statistics. 3rd ed. New York: The Macmillan Co., 1969:225. 11. American Society for Testing and Materials: standard test methods for radiopacity of plastics for medical use ASTM standard 640-79, 1074-1078. 12. McCabe JF, Wilson HJ. A radio-opaque denture materials. J Dent 1976;4:211-7. 13. Beyer-Olsen EM, Orstavik D. Radiopacity of root canal sealers. Oral Surg Oral Med Oral Patho11981 ;51:320-8. 14. Abou-Tabl ZM, Tidy DC, Combe EC. Radiopacity of composite restorative materials. Br Dent J 1979;147:187-8. 15. Combe EC. Studies on radio-opaque dental materials. Dent Pract 1971 ;22:51-4. 16. Price C, Whitehead FIH. Impression materials as foreign bodies. Br Dent J 1972;133:9-14. 17. Melartin E, Tuohimaa P, Dapp R. Neurotoxicity of iothalamates and diatrizoates. I. Significance of concentration and cation. Invest Radiol 1970;5:13-21. 18. Kedama JK, Butler WM, Tusing TW, Hallet FP. Iothalamate: a new intravascular radiopaque medium with unusual pharmacotoxic inertness. Exp Mol Patho11963;2(suppl 2):65-80.

Evaluation of diagnostic radiopaque contrast materials used with calcium hydroxide.

An evaluation of three different radiopaque materials used in combination with calcium hydroxide powder for diagnostic contrast was made. Diatrizoate ...
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