A PREPARATION FOR INHIBITING THE RELEASE OF MERCURY AND FOR RENDERING MERCURY RELEASED FROM AMALGAN FILLINGS HARMLESS

Abstract: A preparation intended to inhibit the release of mercury or to render mercury that is released when treating amalgam dental fillings or when inserting new amalgam fillings, harmless. The preparation contains at least 0.01 percent by weight of a physiologically acceptable organic sulphur compound, which includes at least one group chosen from SH and R1-Sn-R2, where n = 1-6. The use of such a preparation in mouth washes, mouth sprays, toothpastes, dental prophylactic pastes or rinsing/cooling liquids intended for use when drilling, abrading, polishing or cleaning with the aid of dental instruments. The use of cysteine in the preparation of a therapeutic treatment preparation for rendering Hg harmless in solution form and/or gas form in the oral cavities of human beings and animals.

Description: A PREPARATION FOR INHIBITING THE RELEASE OF MERCURY AND FOR RENDERING MERCURY RELEASED FROM AMALGAM FILLINGS HARMLESS The present invention relates to a preparation for inhibiting the release of mercury (Hg) from amalgam and/or rendering mer¬ cury, that is released when treating existing dental amalgam fillings and/or when inserting new amalgam fillings, harmless. The preparation is intended for clinical use, i.e. by dental personnel such as dentists and dental nurses for instance, and also by people whose teeth include amalgam fillings. The prepa¬ ration can also be used on animals. The invention also relates to the use of such a preparation. Problems Mercury is a heavy metal whose toxic effect is well known. Amalgams are alloys which contain relatively large quantities of Hg. Amalgam used in dental fillings contains about 50 percent by weight metallic Hg. Hg is released more or less continuously from the fillings in both vapour form and in the form of solu¬ tion, as a result of the corrosion and the e ' ar that occurs naturally in the oral cavity because of the abrasion between fillings and tooth surfaces, and also as a result of the pH of the saliva. The amount of Hg released will increase when the fillings are subjected to pronounced strain, particularly when chewing, for instance in conjunction with consuming different foodstuffs, and also when brushing the teeth, and may be more than 6-fold in cases such as these. This elevated Hg release will often not diminish until 40-50 minutes have lapsed after termination of this pronounced strain on the fillings. Mercury that is released in vapour form and in the form of a solution is taken up via the lungs or swallowed with saliva. Investigations have shown that the average daily absorption of mercury per person is about 3-17 μg ("Inorganic mercury", Environmental Health Criteria Document 118, WHO 1991) . Although there is some controversy as to whether or not the ingestion of such quanti¬ ties would regularly result in Hg-poisoning, there is no doubt that comparatively highly sensitive persons can be afflicted by these mercury levels. Dental personnel handling amalgam are also exposed to the mer¬ cury that is released during treatment, particularly when in¬ serting new fillings and when polishing and drilling existing fillings. It has been found that on such occasions, the ambient air can have mercury concentration values as high as 50 μg/nr • x measured in the breathing zone (Langworth, S., et al. "Undersδk- ningar av kvicksilverexponering och halsorisker fδrknippade med amalgamhantering"; Slutrapport Arbetsmiljofonden, 1989) . These high levels can be compared with the professional hygienic level li .mi.t currently appli.ed i.n Sweden, whi.ch i.s only 30 μg/m . Description of the known prior art SE-B-463 189 describes a preparation for introduction into the oral cavity. The purpose of this preparation is to prevent the release of Hg and Hg vapour from dental amalgam fillings or to reduce reduce the extent of such release. The preparation con¬ tains sulphur in a free form, preferably in concentrations of 0.1-0.01 percent by weight and in particle sizes in the range of 0.05-0.01 mm. Although it is maintained in the patent specifica¬ tion that the preparation may be present in many different forms, the sole embodiments described with examples are tooth¬ paste and chewing gum, wherein the sulphur grains have an av¬ erage size of 0.025 mm. In the examples documented, the sulphur is present in concentrations of 0.005-5 percent by weight. How¬ ever, it is also anticipated that the preparation may be used in mouth washes, mouth sprays, abrading and polishing agents and as a coolant when using dental instruments. This would create con¬ siderable problems in practice, however. For instance, it is highly unlikely that a colloidal sulphur solution could be used in dental instrument washing liquids without the sulphur par¬ ticles settling to form a sediment, with the subsequent risk of clogging valves and like devices. A corresponding clogging risk would also be likely in the case of a mouth spray. The use of colloidal sulphur in a mouth-washing agent would also appear im¬ practical in view of the unavoidable sedimentation risk. US-A-5 178 541 also describes preparations and methods for preventing release of Hg and Hg vapour. This document also discloses the use of sulphur in such preparations and methods. A protective layer may be formed over hardened amalgam surfaces by brushing with a toothpaste composition containing sulfur. Alter- natively, surfaces of a tooth cavity can be coated with a lining composition containing sulfur before inserting the dental amal¬ gam. Also, sulphur may be incorporated into setting compositions comprising a dental amalgam alloy. Nothing is disclosed about preparations that can be used when polishing and drilling ex¬ isting fillings. WO 88/05295 describes a composition which is intended to prevent poisoning as a result of the dissolution of Hg from amalgam fillings, this composition containing selenium iodide. Selenium compounds, however, are known to be highly toxic, a problem which can hardly be ignored in the present context. Chemical Abstracts, Vol. 105, abstract number 185439c & Twardow- ska-Saucha: Br. J. Ind. Med. 1986, 43(9), 611-14, discloses treatment of mercury poisoning of animals with methicillin or penicillamine. Nothing is revealed about any dental applica¬ tions. Thus, there exists a need for means which are effective in inhibiting the release of Hg and in rendering released Hg harm- less and which are not encumbered with the aforesaid problems. Such means have now been produced in the form of preparations of the kind defined in the introduction, these preparations being characterized by including at least 0.01 percent by weight, calculated on the total on the total weight of the preparation, of at least one physiologically acceptable organic sulphur compound which includes at least one group chosen between SH and R j -S n -R2, wherein n = 1-6, and R j and R2 are organic groups. In addition to solving the aforesaid problems, tests carried on these preparations were found to provide surprisingly good results in comparison with the known technique. According to one embodiment of the present invention, the prepa¬ rations contain sulphur organic compounds, for instance thiols, thiocarboxylic acids or thioaldehydes. Specific examples of sulphur organic compounds are thiocarbamide, dithiodiethanol, 2, 3-dimercaptobutanedioic acid, 2-mercaptobutanedioic acid, 2,3- dimercapto-1-propanol and derivatives thereof. According to one preferred embodiment, the sulphur organic compound is an a ino acid, for instance cysteine, homocysteine, acetylcysteine, cystine, penicillamine, glutathione, methionine or a derivative thereof, an amino acid-hydrochloride or a pro¬ tein, for instance an albumin. According to one particularly preferred embodiment, the sulphur organic compound is cysteine. The compound is present in the inventive preparations in amounts corresponding to up to 10 percent by weight, preferably up to 5 percent by weight, and particularly up to 1 percent by weight, wherein the remainder of the preparation is comprised of up to 100 percent by weight of a physiologically acceptable extender, such as a solvent, for instance, in which the compound is dis¬ solvable at the concentration concerned, preferably water, and possibly other conventional additives for the use in question, such as abrasive agents, flavourants, thickeners, etc. In one particularly preferred embodiment, the preparation in¬ cludes 0.1-5 percent by weight cysteine. According to another embodiment of the present invention, the aforedescribed preparation is used in mouthwashes, toothpaste, tooth prophylactic paste or in rinsing and/or cooling liquid intended for use when drilling, abrading, polishing or cleaning teeth with the aid of dental instruments. In another embodiment of the present invention, cysteine is used in the production of a preparation for therapeutical treatment in the oral cavity of human beings or animals with the intention of rendering harmless Hg in a dissolved and/or gaseous state. One feasible explanation for the effectiveness of the prepara¬ tions is that from a steric aspect, the S n groups and SH groups of the compounds present in the preparations are able to react with Hg atoms and Hg ions relatively unhindered. It is also feasible that the groups in question are caused to react with the amalgam fillings through the medium of a sorption process, wherein not-readily dissolved compounds are formed, and steric hinderance against the release of unreacted Hg atoms is ob¬ tained. The present invention will now be illustrated with the aid of examples and with reference to the accompanying drawings, in which Fig. 1 is a diagram which illustrates intraoral Hg concentration (plotted on the y-axis with the unit μg/nr -x) after brushing the teeth and partly without and partly with subsequent rinsing with water (curve A) and aqueous solutions of colloidal sulphur (5%) (curve B) and cysteine (2%) (curve D) respectively as a function of time (measured in minutes) ; Fig. 2 is a diagram which illustrates air-borne Hg concentra- tions (the y-axis, μg/m , logarithmic scale) at 10 cm above an amalgam filling when drilling the filling, partly without (curve N) and partly with rinsing/cooling with water (curve O) and with aqueous solutions of sulphur (about 1%) (curve P) , colloidal sulphur (1%) (curve Rl) and cysteine (1%) (curve SI) respec¬ tively as a function of time (measured in seconds) ; and Fig. 3 is a diagram which illustrates an Hg concentration (μg/irr It) under the same conditions as those for Fig. 2 (although the scale for the Hg concentration is linear in this case) , in which only comparisons were made, however, between the effect of aqueous solutions of colloidal sulphur (1 (curve R2) and 5% (curve Q) respectively) and cysteine (1%) (curve S2) . Intraoral Hg concentration after brushing the teeth, with and without subsequent treatment Comparison Example I In one test, the concentration of mercury in the air in the oral cavity of a test person having about 15 amalgam dental fillings was measured with the aid of a single-beam atom absorption spectrophotometer manufactured by Centrum for Dental Bioteknik (CDB) , Novum, Huddinge, Sweden, which had been calibrated against a newly calibrated gold film instrument designated "JEROME 411" (marketed by Jerome Corporation, U.S.A.) , which is intended for measuring the concentration of air-borne Hg vapour. The first measuring process was carried out after the amalgam fillings had been at rest for two hours, which in the present context implies that the fillings had not been subjected to any particular form of strain, such as brushing, chewing or the like over this period. Upon completion of this measuring process, the fillings were subjected to wear, or abrasion) by brushing the teeth with a conventional toothpaste that contained an abrasive (fluorine-containing toothpaste bearing the trademark COLGATE®) , whereafter the mouth was rinsed with water. After having rinsed the mouth, the Hg concentration was measured for a second time. A pronounced increase in Hg concentration was established, as evident from Table 1 below and from Fig. 1. Prevailing Hg con¬ centrations in the oral cavity air were then measured after 1, 3, 5, 10, 25 and 40 minutes respectively, at which latter time the Hg concentration had returned essentially to its original value. The results of these measurements are noted in column A of Table 1 below, and also with the aid of curve A in Fig. 1. Comparison Example II The test of Comparison Example I was repeated, with the excep- tion that the mouth was washed out immediately after brushing the teeth, followed by rinsing with a colloidal aqueous solution containing 5 percent by weight of sulphur, calculated on the total weight of the solution, having a particle size of up to about 12 μm (marketed by Fluka Chemie AG, Buchs, Switzerland) . The Hg concentration in the oral cavity air was measured partly when the fillings ha-d been at rest for two hours (according to the definition in Comparison Example I) , and partly in conjunc¬ tion with brushing the teeth and the subsequent rinsing of the mouth, and 1, 3, 5, 10, 25 and 40 minutes respectively after rinsing the mouth. The results obtained with these measuring processes are noted in column B in Table 1 below and also with the aid of curve B in Fig. 1. Comparison Example III The test of Comparison Example II was repeated, but with the exception that the mouth was rinsed with a colloidal aqueous solution containing 2 percent by weight sulphur, calculated on the total weight of the solution. The Hg concentration of the oral cavity air was measured in the same way as in Comparison Example II. The results obtained from these measuring processes are noted in column C in Table 1 below. EXAMPLE 1 The -test of Comparison Example II was repeated, but with the exception that the mouth was rinsed with an aqueous solution that contained 2 percent by weight cysteine, calculated on the total weight of the solution. The Hg concentration in the oral cavity air was measured in the same way as that in Comparison Example II. The results of these measuring processes are noted in column D in Table 1 below and also with the aid of curve D in Fig. 1. EXAMPLE 2 The test carried out in Comparison Example II was repeated, but with the exception that the mouth was rinsed with an aqueous solution that contained 2 percent by weight homocysteine, cal¬ culated on the total weight of the solution. The Hg concentra¬ tion in the oral cavity air was measured in the same way as in Comparison Example II. The results of these measuring processes are noted in column E in Table 1 below. EXAMPLE 3 The test carried out in Comparison Example II was repeated, but with the exception that the mouth was washed with an aqueous solution containing 2 percent by weight of acetylcystein, cal¬ culated on the total weight of the solution. The Hg concentra¬ tion in the oral cavity air was measured in the same way as in Comparison Example II. The results of these measuring processes are noted in column F in Table 1 below. EXAMPLE 4 The test carried out in Comparison Example II was repeated, but with the exception that the mouth was rinsed with an aqueous solution that contained 2 percent by weight of 2, 3-dimercaptobu- tanedioic acid, calculated on the total weight of the solution. The Hg concentration in the oral cavity air was measured in the same way as in Comparison Example II. The results of these measuring processes are noted in column G in Table 1 below. EXAMPLE 5 The test carried out in Comparison Example II was repeated, but with the exception that the mouth was rinsed with an aqueous solution that contained 2 percent by weight of 2-mercaptobutane- dioic acid, calculated on the total weight of the solution. The Hg concentration in the oral cavity air was measured in the same way as in Comparison Example II. The results of these measuring processes are noted in column H in Table 1 below. EXAMPLE 6 The test carried out in Comparison Example II was repeated, but with the exception that the mouth was rinsed with an aqueous solution that contained 2 percent by weight penicillamine, cal¬ culated on the total weight of the solution. The Hg concentra¬ tion in the oral cavity air was measured in the same way as in Comparison Example II. The results of these measuring processes are noted in column I in Table 1 below. EXAMPLE 7 The test carried out in Comparison Example II was repeated, but with the exception that the mouth was washed with an aqueous solution containing 2 percent by weight human standard albumin, calculated in the total weight of the solution (marketed in a 0.85% NaCl solution by Sigma, St. Louis, Missouri, U.S.A.) . The Hg concentration in the oral cavity air was measured in the same way as in Comparison Example II. The results of these measuring processes are noted in column K in Table 1 below. EXAMPLE 8 The test carried out in Comparison Example II was repeated, but with the exception that the mouth was washed with an aqueous solution containing 2 percent by weight of glutathione, cal¬ culated on the total weight of the solution. The Hg concentra¬ tion in the oral cavity air was measured in the same way as in Comparison Example II. The results of these measuring processes are noted in column L in Table 1 below. EXAMPLE 9 The test carried out in Comparison Example II was repeated, but with the exception that the mouth was washed with an aqueous solution containing 2 percent by weight 2 , 3-dimercapto-l-pro- panol, calculated on the total weight of the solution. The Hg concentration in the oral cavity air was measured in the same way as in Comparison Example II. The results of these measuring processes are noted in column M in Table 1 below. As will be seen from Table 1, all of the solutions used in the Examples had a positive effect with regard to the Hg concen¬ tration in the oral cavity air during the first five minutes after treatment. Surprisingly, cysteine, homocysteine, 2-3- TABLE 1: Intraoral Hg concentration in oral cavity air after brushing the teeth and subsequen rinsing, measured in μg/πr Time B E H K M Rest 10 10 10 10 10 10 10 10 10 10 10 10 ("V" in Fig 1) After brushing/ 50 50 50 50 50 50 50 50 50 50 50 50 washing ("X" in Fig 1) After mouth 50 20 22 3 4 12 6 10 30 40 15 3 washing ("p" in Fig 1) 1 min 50 24 26 4 6 14 8 12 33 35 14 2 3 min 45 23 24 6 10 17 8 11 35 35 16 2 5 min 45 20 22 8 12 16 10 11 35 35 20 3 10 min 30 18 20 10 12 18 12 12 34 30 20 5 25 min 25 15 16 12 11 16 10 15 30 25 16 8 40 min 10 10 10 10 10 12 10 12 12 12 10 12 -dimercapto-1-propanol and 2,3-dimercaptobutandioic acid in 2% aqueous solution gave much better results than a colloidal aqueous sulphur solution, even a 5% solution. A separate compa- rison between the measuring results obtained in Comparison Ex¬ amples I and II and Example 1 is shown in the diagram in Fig. 1, in which the Hg concentration is plotted on the y-axis in μg/m J , and the time is plotted on the x-axis in minutes. This compari¬ son clearly shows that a cysteine solution is much more effec- tive than a colloidal sulphur solution for the purpose in ques¬ tion. Intraoral Hg concentration when drilling amalgam fillings and with and without simultaneous rinsing/cooling with different aqueous solutions Comparison Example IV In one test, the Hg concentration of the air was measured 10 cm above an amalgam filling in a plaster model of a toothed jaw, on which drilling work was performed. The drilling and measuring processes had a duration of 20 seconds. The Hg concentration was measured with the same equipment and in accordance with the same calibration as in Comparison Example I. The measuring results obtained immediately prior to drilling (i.e. at 0 seconds) and at 5, 10, 15 and 20 seconds respectively after commencing dril¬ ling are noted in column N in Table 2 below, and with the aid of curve N in Fig. 2. Comparison Example V The test carried out in Comparison Example IV was repeated, but with the exception that drilling was carried out while cooling with the aid of a cooling water spray and an air spray (i.e. comparable with conventional water cooling in conjunction with dental work) . The Hg concentration in the air was measured in the same way as in Comparison Example IV. The results of these measuring processes are noted in column 0 in Table 2 below, and with the aid of curve 0 in Fig. 2. Comparison Example VI The test carried out in Comparison Example IV was repeated, but with the exception that drilling was carried out while cooling with the aid of a sprayed-on cooling water solution containing a sulphur slurry in an amount corresponding to about 1 percent by weight calculated on the total weight of the solution. The Hg concentration in the air was measured in the same way as in Comparison Example IV. The results of these measuring processes are noted in column P in Table 2 below, and with the aid of curve P in Fig. 2. Comparison Example VII The test carried out in Comparison Example IV was repeated, but with the exception that drilling was performed while cooling with the aid of a sprayed-on cooling water solution containing colloidal sulphur in an amount corresponding to 5 percent by weight calculated on the total weight of the solution. The Hg concentration in the air was measured in the same way as in Comparison Example IV. The results of these measuring processes are noted in column Q in Table 2 below, and with the aid of curve Q in Fig. 3. Comparison Example VIII The test carried out in Comparison Example IV was repeated, but with the exception that drilling was performed while cooling with the aid of a sprayed-on cooling water solution containing colloidal sulphur in an amount corresponding to 1 percent by weight of the total weight of the solution. The Hg concentration in the air was measured in the same way as in Comparison Example IV. The results of these measuring processes are noted in column R in Table 2 below, and with the aid of curve Rl in Fig. 2 and with the aid of curve R2 in Fig. 3. EXAMPLE 10 The test in Comparison Example IV was repeated, but with the exception that drilling was performed while cooling with the aid of a sprayed-on cooling water solution containing cysteine in amount corresponding to 1 percent by weight calculated on the total weight of the solution. The Hg concentration in the air was measured in the same way as in Comparison Example IV. The results of these measuring processes are noted in column S in Table 2 below, and with the aid of curve SI in Fig. 2 and with the aid of curve S2 in Fig. 3. TABLE 2: Intraoral Hg concentration in oral cavity air when drilling amalgam fillings with and without rinsing/- cooling with the aid of different aqueous solutions, measured in μg/πr Time M 0 P Q R S 0 s 2 2 2 4 2 2 5 s 140 25 20 5 8 2 10 s 150 40 30 7 10 4 15 s 250 50 45 8 12 2 20 s 200 45 40 7 12 3 It is clearly apparent from Table 2 and from Figs. 2 and 3 that a 2% aqueous solution of cysteine is much more effective than a colloidal sulphur solution or a sulphur slurry, even a 5% solu¬ tion or slurry, with regard to rendering Hg harmless in the oral cavity. It will be understood that the invention is not restricted to the application described by way of demonstration in the above Examples and that there are many more ways of administering the inventive preparation that will be found natural by one skilled in this art.

Claims: CLAIMS 1. A preparation for inhibiting the release of mercury from amalgam and/or rendering the mercury, that is released in the air or in the mouth of a patient when treating amalgam fil¬ lings in teeth and/or when inserting new amalgam fillings, harm¬ less, characterized in that the preparation contains at least 0.01 percent by weight of at least one physiologically accep¬ table organic sulfur compound which includes at least one group chosen from -SH and R j -S n -R2, wherein n = 1-6, and R j and R2 are organic groups. 2. A preparation according to Claim 1, characterized in that the compound is 2, 3-dimercaptobutanedioic acid or a deri- vative thereof, such as mercaptobutanedioic acid. 3. A preparation according to Claim 1, characterized in that the sulphur organic compound is an amino acid, an amino acid hydrochloride, or a protein. 4. A preparation according to Claim 3, in which the com¬ pound is a protein, characterized in that the protein is an albumin. 5. A preparation according to Claim 3, in which the com¬ pound is an amino acid, characterized in that the amino acid is chosen from a group that includes cysteine, homocysteine,acetyl- cysteine, cystine, penicillamine, glutathione, methionine and derivatives thereof. 6. A preparation according to Claim 5, characterized in that the amino acid is cysteine. 7. A preparation according to Claim 1, characterized in that the compound is 2,3-dimercapto-l-propanol. 8. A preparation according to any one of the preceding Claims, characterized in that the preparation includes up to 10 percent by weight of the compound. 9. A preparation according to any one of Claims 1-7, characterized in that the preparation includes up to 5 percent by weight of the compound. 10. A preparation according to any one of Claims 1-7, charac¬ terized in that the preparation includes up to 1 percent by weight of the compound. 11. A preparation according to Claim 6, characterized in that the preparation includes 0.1-5 percent by weight cysteine. 12. The use of cysteine for preparing a preparation for the therapeutical treatment of the oral cavities of human beings or animals with the purpose of rendering Hg in solution and/or gas form harmless. 13. The use of a preparation according to any one of Claims 1- 11 in mouth-washing liquid, mouth spray, toothpaste, tooth prophylactic paste or in rinsing and/or cooling liquid intended for use when drilling, abrading, polishing, or cleaning with the aid of dental instruments.

Inventors: LANGWORTH SVEN, LANGWORTH, SVEN
Applicants: LANGWORTH SVEN, LANGWORTH, SVEN
Application year: 1995
Main classification: A61K7
IPC codes: A61K6, A61K8, A61Q11