Two-component system

Abstract

A two-component system for the preparation of a hydrogel for preventing and/or treating a periodontal disease, selected from the group consisting of periimplantitis, gingivitis, periodontitis and peri-implant mucositis. The two-component system comprises as a first component an aqueous suspension having a pH value of less than 7 comprising a pH-sensitive gelling agent, and as a second component a sodium hypochlorite (NaOCl) solution at a pH in the range of 10 to 13. The first component is physically separated from the second component.

Claims

1. A two-component system for the preparation of a hydrogel having a viscosity of more than 40,000 mPa*s at 20 C. for preventing and/or treating a periodontal disease, comprising: a) as a first component, an aqueous suspension having a pH value of less than 7 comprising at least one pH-sensitive gelling agent, b) as a second component, a sodium hypochlorite (NaOCl) solution at a pH in the range of 10 to 13, a concentration of the sodium hypochlorite solution in the second component being in a range of from 0.7 to 4.2% by weight, wherein the first component is physically separated from the second component.

2. The two-component system according to claim 1, wherein the suspension comprising the at least one pH-sensitive gelling agent has a viscosity of less than 4000 mPa*s at 20 C.

3. The two-component system according to claim 1, wherein the sodium hypochlorite solution of the second component has a pH in a range of from 11 to 13.

4. The two-component system according to claim 1, wherein the at least one pH-sensitive gelling agent is a crosslinked polyacrylic acid.

5. The two-component system according to claim 1, wherein the aqueous suspension comprising the at least one pH-sensitive gelling agent additionally comprises a non-toxic pH sensitive colorant.

6. The two-component system according to claim 1, wherein said system is a dual cartridge or a dual syringe.

7. A hydrogel obtainable by mixing the two components of the two-component system according to claim 1.

8. The hydrogel according to claim 7, wherein the hydrogel has a pH in a range of from 6.0 to 9.5.

9. The hydrogel according to claim 6, wherein the hydrogel has a sodium hypochlorite concentration in a range of from 0.1 to 0.7% by weight of the total weight of the gel.

10. A kit of parts for treating a periodontal disease, selected from the group consisting of periimplantitis, gingivitis, periodontitis, and peri-implant mucositis, comprising: (a) the two-component system according to claim 1, and (b) a composition comprising chlorhexidine (CHX).

11. The kit of parts according to claim 10, wherein the composition comprising chlorhexidine is an aqueous solution or a hydrogel.

12. The kit of parts according to claim 10, wherein the composition comprising chlorhexidine is a two-component system comprising: (a) as a first component, an aqueous suspension comprising a pH-sensitive gelling agent, and (b) as a second component, a chlorhexidine solution having a pH which is above the gelling pH of the at least one pH-sensitive gelling agent.

13. A method for treating a periodontal disease selected from the group consisting of periimplantitis, gingivitis, periodontitis, and peri-implant mucositis, the method comprising: administering the hydrogel according to claim 7 to a site of infection in a patient suffering from the periodontal disease.

14. The two-component system according to claim 2, wherein the viscosity of the suspension comprising the at least one pH-sensitive gelling agent is less than 1500 mPa*s at 20 C.

15. The two-component system according to claim 3, wherein the pH of the sodium hypochlorite solution of the second component is in a range of from 11 to 12.

16. The two-component system according to claim 5, wherein the non-toxic pH sensitive colorant is selected from the group consisting of methylene blue, indigocarmine, methyl green, bromocresol green, sodium alizarine sulphonate, chlorophenol red, bromthymol purple, bromthymol blue, azolitmin, neutral red, cyanine, phenol, phenol red, cresol red, thymol blue, -Na phenolphthaleine, phenolphthaleine, -Na phthalein, thymolphthaleine, nile blue, alizarine yellow, methyl violet, methyl yellow, bromphenol blue, paranitrophenol, bromphenol purple, and litmus.

17. The two-component system according to claim 16, wherein the non-toxic pH sensitive colorant is methylene blue or litmus.

Description

LEGEND OF THE FIGURES

(1) FIG. 1: A 1% NaOCl solution was stored at 4 C., room temperature and 44 C. Over the period of 1 month only the sample stored at 44 C. showed a decrease in concentration.

(2) FIG. 2: A 5% NaOCl solution was stored at 4 C., room temperature and 44 C. Over the period of 1 month no significant difference in concentration for the samples at 4 C. and room temperature was observed. The sample at 44 C. showed a loss of concentration of about 40%.

(3) FIG. 3: A 10% NaOCl solution was stored at 4 C., room temperature and 44 C. Over the period of 1 month no significant difference in concentration for the samples at 4 C. and room temperature was observed. The sample at 44 C. showed a decrease in concentration of over 70%.

(4) FIG. 4: 0.6% NaOCl solution stored at r.t., pH=11.4 and exposed to sunlight (square), stored at 44 C., pH=11.5 (circle) and >12 (triangle) in the dark.

(5) FIG. 5: Viscosity measurement of the 4 promising combinations. All samples were prepared and measured twice and the mean value is displayed here. The higher the dilution and the lower the NaOCl concentration, the lower is the viscosity.

(6) FIG. 6: Comparison between 2% Carbopol with a final NaOCl concentration of 0.1% and 0.3% mixed with solution 2 (0.4 g). Both samples were mixed and measured twice to investigate the experiment's reproducibility.

(7) FIG. 7: Comparison between 2% Carbopol with a final NaOCl concentration of 0.1% and 0.3% mixed with solution 3 (0.8 g). Both samples were mixed and measured twice to investigate the experiments reproducibility.

(8) FIG. 8: Effect of NaOCl concentration on the viscosity of 1.5% Carbopol ETD 2020 N F. The higher the hypochlorite concentration, the more liquid is the sample.

(9) FIG. 9: Yield point measurements of 2% Carbopol 975P NF (1.0 g) mixed with solution 2 (0.4 g) or solution 3 (0.8 g) with a final NaOCl concentration of 0.1% or 0.3%. The higher the NaOCl content and the lower the final Carbopol concentration the lower is the yield point.

PREPARATION OF CARBOPOL GEL

Example: Carbopol 974P NF Polymer

(10) 1%, 2% and 3% Carbopol 974P NF suspensions have been prepared. Methylene blue (4 mg) was dissolved in reverse Osmosis H.sub.2O (300 mL, MilliQ) which resulted in a blue coloured solution. This solution (99 g) in a 250-mL-beaker was placed under the mechanical stirrer with a ringed propeller under a slight angle (ca. 10-20). Carbopol 974P NF polymer (1 g) was added while stirring at 400 rpm and stirring was continued for 90 min or until no lumps were visible anymore. The suspension was filled in two 50-mL-falcon tubes.

(11) TABLE-US-00001 TABLE 1 Preparation of the 1%, 2% and 3% Carbopol 974P NF suspensions used in the two component system. H.sub.2O Carbopol 1% Carbopol 974P NF 99 g 1.0 g 2% Carbopol 974P NF 98 g 2.0 g 3% Carbopol 974P NF 97 g 3.0 g

Preparation of Basic Solutions

Example: Solution 2 for 0.3% NaOCl Final Concentration

(12) NaOH.sub.aq (1 M, 10 mL), reverse osmosis H.sub.2O (10 mL) and NaOCl.sub.aq (10%, 2 mL) were mixed. pH and NaOCl concentration were measured. For each experiment 4 solutions were prepared (see Table 2).

(13) TABLE-US-00002 TABLE 2 Preparation of the 4 solutions for final NaOCl concentrations of 0.7%, 0.3% and 0.1%. [NaOH] [NaOCL] 1M 0.1M 10% in in NaOH.sub.aq NaOH.sub.aq H.sub.2O NaOCl.sub.aq solution.sup.a solution.sup.b final concentration: 0.7% NaOCl Solution 1 7.0 mL 5.0 mL 1 M 4.17% Solution 2 10.0 mL 10.0 mL 7.0 mL 0.5 M 2.59% Solution 3 3.8 mL 11.2 mL 3.0 mL 0.25 M 1.67% Solution 4 7.0 mL 0.8 mL 0.1 M 1.03% final concentration: 0.3% NaOCl Solution 1 8.0 mL 2.0 mL 1 M 2.00% Solution 2 10.0 mL 10.0 mL 2.5 mL 0.5 M 1.11% Solution 3 3.8 mL 11.2 mL 1.2 mL 0.25 M 0.74% Solution 4 8.0 mL 0.4 mL 0.1 M 0.48% final concentration: 0.1% NaOCl Solution 1 9.0 mL 0.7 mL 1 M 0.763% Solution 2 10.0 mL 10.0 mL 0.8 mL 0.5 M 0.428% Solution 3 3.8 mL 11.2 mL 0.4 mL 0.25 M 0.265% Solution 4 10.0 mL 0.2 mL 0.1 M 0.213% .sup.anot including the NaOH contained in the NaOCl solution .sup.bx mL 10% NaOCl.sub.aq/(y mL NaOH.sub.aq + z mL H.sub.2O + x mL 10% NaOCl.sub.aq)
Syringes and Mixing

(14) The Carbopol 974P NF polymer suspension (1 g) and solutions 1 (0.2 g, Table 2), 2 (0.4 g), 3 (0.8 g) and 4 (2 g) were each weighed into 2-mL-syringes with Luer lock. The connector was fixed between two syringes (one containing polymer, the other one of the solutions) and the two components were mixed until the blue colour was not visible anymore. After mixing, the NaOCl concentration was determined by titration. The viscosity, yield point and pH were measured for a number of representative samples.

(15) Titrations

(16) The NaOCl concentration was determined by iodometric titration. The samples were measured one to three times (see Table 8).

(17) Rheological Measurements

(18) Ca. 300 L of the hydrogel were placed on the Peltier element (25 C.), the cone (diameter: 24.952 mm, angle: 2.009, truncation: 51 m) was lowered to d=0.105 mm and excess material was removed with a spatula. Water droplets were placed around the stamp and the temperature hub was lowered. Then, preshear of d()/dt=50 l/s was briefly applied, the sample was allowed to rest for 10 min, and a shear rate sweep from d()/dt=0.005 to 500 l/s was started.

(19) Subsequently, the yield point, i.e. the stress at which the sample begins to deform, was determined for a number of representative samples.

(20) Quality of the Starting Solution with Regard to Metals

(21) Despite the fact, that the shelf life of NaOCl is short and may be influenced by several factors (e.g. temperature, pH, light, concentration and presence of transition metals), it was found, that a high quality could be reached. As the quality of the NaOCl is important, the amount of transition metals was analysed by elemental analysis (Table 3).

(22) TABLE-US-00003 TABLE 3 Result of elemental analyses of two NaOCl samples (1% and 10% in reverse Osmosis H.sub.2O (MilliQ)). 1% NaOCl solution 10% NaOCl solution Element [ppb] [ppb] Ca 75.8 687 Co <8 <80 Cu <10 107 Hg <0.1 <1 Fe <2 <20 Mg <0.2 <2 Mn <0.6 <6 Ni <1 <10

(23) All values are in the acceptable range for high quality NaOCl solutions. As the 1% solution was diluted from the 10% solution the data corresponds well.

(24) Sterilisation

(25) Sterilisation may also affect the available chlorine concentration (Table 4). Possible methods are autoclaving (samples were heated to 121 C. for 15 minutes), -sterilisation (samples were -irradiated with a dose of 25 to 42 kGy or filtration (samples were filtered over a PVDF 0.2 m syringe filter).

(26) -Sterilisation showed the severest reduction in NaOcl concentration, followed by autoclaving. Filtration over a polyvinylidene fluoride (PVDF) filter did not affect the hypochlorite concentration (see Table 4).

(27) TABLE-US-00004 TABLE 4 Effect of sterilisation methods on the concentration of a 0.7% NaOCl solution. After autoclaving the sample and -sterilisation a reduction of the NaOCl content was detectable. This was not the case for the filtration. [NaOCl].sub.initial [NaOCl].sub.final 15 min/121 C. 0.7% 0.6% -sterilization 0.5% filtration (PVDF) 0.7%
Shelf Life

(28) Upon storage at 4 C., room temperature and 44 C. in the dark (FIGS. 1-3), 1%, 5% and 10% NaOCl solutions showed similar degradation as predicted by a literature model. High temperature and concentration accelerate the degradation process. In line with these observations are the commercially available NaOCl solutions from Hedinger. Their products are more stable the lower the concentration (1% NaOCl solution: 18 months, 3% NaOCl solution: 12 month). For the 1% NaOCl solution the sample stored at 44 C. showed degradation (FIG. 1). The concentration of the probes stored at 4 C. and room temperature did not change during the time of the experiment. Literature suggests that for a temperature increase of 10 C. degradation is 3.5 times faster. Thus, the sample stored at room temperature corresponds to 10 times the storage time at 4 c.

(29) Storage of a 0.6% NaOCl solution at room temperature exposed to light did not show an immediate effect on the concentration (FIG. 4, square). Storage of the same 0.6% NaOCl solution at 44 C. (pH=11.5) showed degradation after a month (circle). The pH also decreased to 8. Storage of a 0.6% NaOCl solution with excess NaOH (1 M NaOH.sub.aq was added until pH>12) did not degrade during the 41 days of the experiment (triangle). Therefore, as soon as the pH drops out of the preferred range (pH=11-13), degradation is dramatically accelerated and that the hypochlorite concentration is affected more by temperature than by natural daily light exposure.

(30) Carbopol Gels

(31) Carbopol is a high molecular weight polymer of acrylic acid, which is commercially available.

(32) Basic solutions 1-4 were prepared for each targeted final NaOCl concentration and directly used in the experiment (Table 5). Each solution has been mixed with 1.0 g carbopol solution.

(33) TABLE-US-00005 TABLE 5 % NaOCl % NaOCl amount used theoretical* measured pH final concentration in the hydrogel to be produced: 0.7% NaOCl Solution 1 (1M 0.2 g 4.17 4.03 14 NaOH) Solution 2 (0.5M 0.4 g 2.59 2.58 13.5 NaOH) Solution 3 (0.25M 0.8 g 1.67 1.65 13.2 NaOH) Solution 4 (0.1M 2.0 g 1.03 1.01 12.5 NaOH) final concentration in the hydrogel to be produced: 0.3% NaOCl Solution 1 (1M 0.2 g 2 2.08 14 NaOH) Solution 2 (0.5M 0.4 g 1.11 1.15 23.5 NaOH) Solution 3 (0.25M 0.8 g 0.74 0.707 13.1 NaOH) Solution 4 (0.1M 2.0 g 0.48 0.505 ca. 13 NaOH) final concentration in the hydrogel to be produced: 0.1% NaOCl Solution 1 (1M 0.2 g 0.72 0.763 13.5 NaOH) Solution 2 (0.5M 0.4 g 0.38 0.428 13.3 NaOH) Solution 3 (0.25M 0.8 g 0.26 0.265 13.1 NaOH) Solution 4 (0.1M 2.0 g 0.2 0.213 12.6 NaOH)

(34) The concentration of the solutions should not be too high, as degradation would be accelerated (Table 5, e.g. 4.17% for solution 1 with a final NaOCl concentration of 0.7%). However, a very low hypochlorite concentration is less preferred (e.g. 0.38-0.2% for solution 2-4 with a final NaOCl concentration of 0.1%) due to the fact that only slight changes (e.g. due to trace impurities) during storage may have bigger impact on the concentration in the hydrogel and therefore, on its effectiveness. Nevertheless, the experiment was carried out for all solutions and the desired NaOCl concentration was approximately reached after mixing (Table 6). Hydrogel formation was partially observed, which is indicated by a colour code in Table 6.

(35) TABLE-US-00006 TABLE 6 Results of the two-component system. [Carb.].sub.i stands for the concentration of the used carbopol solution, [NaOCl].sub.f stands for the target concentration of NaOCl. [NaOCl].sub.t indicates the titrated final NaOCl concentration (after mixing). [NaOCl].sub.t Sol. 1 Sol. 2 Sol. 3 Sol. 4 Sample [Carb.].sub.i 1M NaOH 0.5M NaOH 0.25M NaOH 0.1M NaOH [NaOCl].sub.f Experiment 1 1% 0.70%.sup.1) 0.66%.sup.1) 0.62%.sup.1) 0.65%.sup.1) 0.70% Experiment 2 2% 0.55%.sup.3) 0.55%.sup.3) 0.68%.sup.2) 0.81%.sup.1) Experiment 3 3% 0.64%.sup.3) 0.63%.sup.3) 0.61%.sup.3) 0.61%.sup.2) Experiment 1 1% 0.62%.sup.1) 0.68%.sup.1) 0.68%.sup.1) 0.64%.sup.1) 15 min/121 C. Experiment 2 2% 0.67%.sup.3) 0.73%.sup.3) 0.65%.sup.2) 0.65%.sup.1) 15 min/121 C. Experiment 3 3% 0.55%.sup.3) 0.64%.sup.3) 0.59%.sup.3) 0.60%.sup.2) 15 min/121 C. DA050 1% 0.33%.sup.2) 0.32%.sup.1) 0.31%.sup.1) 0.33%.sup.1) 0.30% 15 min/121 C. DA051 2% 0.32%.sup.3) 0.27%.sup.3) 0.29%.sup.3) 0.32%.sup.3) 15 min/121 C. DA052 3% 0.26%.sup.3) 0.26%.sup.3) 0.31%.sup.3) 0.30%.sup.3) 15 min/121 C. DA053 1% 0.13%.sup.3) 0.15%.sup.2) 0.12%.sup.1) 0.14%.sup.1) 0.10% 15 min/121 C. DA054 2% 0.09%.sup.3) 0.12%.sup.3) 0.11%.sup.3) 0.14%.sup.3) 15 min/121 C. .sup.1)no gel formation; .sup.2)gel-like; .sup.3)gel formation. 15 min/121 C.: autoclaved Carbopol solution

(36) 2% Carbopol 974P NF mixed with solution 2 or 3 for a final concentration of 0.1% or 0.3% NaOCl was considered to be a promising range and therefore, the viscosity of these four combinations was measured (FIG. 8) and the yield point was determined (Table 7 and FIG. 9). The higher the NaOCl content and the lower the final Carbopol concentration the lower is the yield point. The viscosity was measured and prepared twice for each sample in order to investigate reproducibility (FIGS. 6 and 7). The yield points and the viscosities show the trend that the more NaOCl is added and the more liquid is added (corresponds to lower base concentration) the less viscous the gel. This was also observed during a different experiment and is displayed in FIG. 8.

(37) TABLE-US-00007 TABLE 7 Yield point measurements: Yield point [Pa] 1.2% Carbopol 974P NF 219 1.2% Carbopol 974P NF 15 min/ 143 121 C. 1.5% Carbopol 974P NF 229 1.5% Carbopol 974P NF 15 min/ 103 121 C. 2% Carbopol 974P NF, 0.1% NaOCl, 80.8 solution 2 2% Carbopol 974P NF, 0.1% NaOCl, 47.1 solution 3 2% Carbopol 974P NF, 0.3% NaOCl, 43.2 solution 2 2% Carbopol 974P NF, 0.3% NaOCl, 19.0 solution 3

(38) Some samples did not form a hydrogel during the two-component experiment. As the amount of the added basic NaOCl solution was dependent on its base concentration and therefore, the Carbopol was diluted to a varied extend. Therefore, the ratio NaOCl/Carbopol may have been too high for some formulations (Table 8).

(39) TABLE-US-00008 TABLE 8 Final Carbopol concentrations after mixing with the different amounts of the basic hypochlorite solutions. 1% Carbopol 2% Carbopol 3% Carbopol (1 g) (1 g) (1 g) Solution 1 0.83% 1.67% 2.50% (0.2 g) Solution 2 0.71% 1.43% 2.14% (0.4 g) Solution 3 0.56% 1.11% 1.67% (0.8 g) Solution 4 0.33% 0.67% 1.00% (2.0 g)

(40) Carbopol polymers are sensitive to salts in general. In the case of a higher NaOCl concentration, this is a disadvantage, as it has to be compensated by a higher Carbopol concentration in order to induce hydrogel formation. However, to remove the hydrogel from the implant after application this feature may be very useful. Saline, which is used for rinsing, is expected to rapidly liquefy and dissolve the hydrogel and thus simplify its removal.

CONCLUSIONS

(41) Best results could be obtained by two-component system resulting in a hydrogel containing 0.1%-0.3% NaOCl. One syringe contains a suspended Carbopol polymer, preferably Carbopol 974, Carbopol 980 or Carbopol ETD 2020 or a mixture thereof, with a colorant (e.g. methylene blue) at low pH, preferably pH 1 to 3.5, most preferably pH 2 to 3.5, the other contains a NaOCl solution at high pH (e.g. 0.5 M NaOH, 1.11% NaOCl). At low pH, the Carbopol suspension is liquid and the high pH of the NaOCl solution warrants its stability. Prior to application, the two syringes are connected and their contents mixed. Decolouration indicates sufficient mixing and the resulting neutralization of the systems leads to formation of a colourless and transparent hydrogel. The hydrogel contains preferably 0.1%-0.3% NaOCl (depending on storage time) and it has a pH of 6.5-7.5.