HIGHLY EFFECTIVE, SILICON-FREE, STORAGE-STABLE DENTAL CAUGHT GEL

Description

[0001] The present invention relates to a dental etching composition, the use of this dental etching composition for etching dental hard tissue, a dental etching composition for use in a therapeutic method for etching dental hard tissue in the context of filling therapy, and a kit containing a dental etching composition. Insofar as certain embodiments are designated as preferred for one aspect of the invention (composition; use; application in a therapeutic method or kit), the corresponding descriptions also apply to the other aspects of the present invention. mutatis mutandis.Preferred individual features of aspects of the invention (as defined in the claims and / or disclosed in the description) can be combined with one another and are preferably combined with one another, unless otherwise apparent to the person skilled in the art from the present text in the individual case; the subject matter of the invention is defined by the claims. Dentin and enamel as hard tooth substance

[0002] Tooth structure consists of enamel and dentin. While enamel is composed of 95% inorganic matter, 4% water, and 1% organic matrix components, dentin, also known as tooth liner, is less mineralized. It forms the main mass of the tooth, represents vital hard tissue, and gives the tooth its specific shape. Dentin surrounds the pulp and is covered coronally by enamel and in the root area by cementum. Dentin originates from the dental papilla and is comparable to bone in its chemical composition. It differs fundamentally from enamel. Dentin consists of 70% inorganic components, primarily hydroxyapatite, approximately 20% organic components, and about 10% water. Due to its high organic content, dentin is highly elastic and malleable.

[0003] The mineralized portion consists primarily of calcium and phosphorus, variable concentrations of fluoride, small amounts of carbonates and magnesium, as well as some trace elements. The organic matrix comprises over 90% type I collagen. The remaining organic substances consist of non-collagenous components such as proteins, lipids, citrates, and lactates.

[0004] In its morphological structure, dentin consists of the dentinal tubules with their periodontoblastic space, the odontoblasts with their processes, the peritubular dentin, the intertubular dentin, and the mantle dentin. Intertubular dentin is the network composed of type I collagen in which the plate-like hydroxyapatite crystals and dentin fluid are embedded. The tubules contain the peritubular dentin, a collagen fiber tube, odontoblast processes, and dentin fluid. The peritubular dentin, which lines the tubule walls, is homogeneous, dense, and the most highly mineralized of all dentin structures.

[0005] The number and diameter of dentinal tubules decrease from the pulp to the dentin-enamel junction. While there are an average of 45,000 tubules / mm² at the pulp-dentin junction, this number decreases to 20,000 / mm² at a distance of 3 mm from the pulp. The diameter decreases from 2 to 3 µm at the pulp to 0.5 to 0.9 µm at the dentin-enamel junction.

[0006] The odontoblasts, the dentin-producing cells of the tooth, are located on the inner surface of the dentin. After differentiation, they are no longer capable of division, but they remain capable of forming secondary and tertiary dentin throughout the tooth's life. The odontoblast processes run within the dentinal tubules. Each process is enveloped by tissue fluid, the dentin fluid, which fills the periodontoblastic space. The processes penetrate the entire dentin and can be up to 5,000 µm long. Lateral branches extending into the intertubular dentin are in contact with the lateral branches of neighboring processes. The periodontoblastic space between the odontoblasts consists primarily of tissue fluid. The intertubular dentin separates the individual dentinal tubules. It is less mineralized than the peritubular dentin.

[0007] During tooth preparation, the dentinal tubules are inevitably opened. This creates an open dentin wound, which, due to the internal pulp pressure, allows dentin fluid to flow outwards along the tubules. This phenomenon is also known as intrinsic moisture. For this reason, dentin cannot be completely dried in vivo.

[0008] When dentin is prepared (for example, with rotary instruments), a 1.5 µm thick smear layer forms, consisting of 0.5 to 1.5 µm particles of tooth structure, collagen, blood and saliva components, as well as bacteria and their metabolic products. This layer clogs the dentinal tubules and also coats the prepared dentin, reducing its permeability. This smear layer cannot be rinsed off or removed mechanically. It therefore hinders the adaptation of restorative materials to the tooth surface and impairs the adhesion of composite resins. However, the smear layer can be removed by chemical pretreatment of the dentin.

[0009] In contrast, the inorganic substance of the melt consists mainly of calcium phosphate in the form of hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ], which, however, cannot be considered stoichiometrically pure due to inclusions of carbonate, fluoride, sodium, magnesium, potassium, and other ions. Fluorapatite or fluoridated hydroxyapatite can be formed through internal substitution reactions. The crystal structures of these compounds are more acid-stable than those of pure hydroxyapatite.

[0010] The proportion of inorganic compounds varies between 93 and 98 wt%, depending on the analytical method and sampling site. Water, the second largest component, varies between 1.5 and 4 wt%. Due to the differing concentrations of the enamel composition at various locations within the tooth, the amounts of fluoride, iron, tin, chlorine, and calcium decrease from the surface to the depth of the tooth, with the fluoride concentration increasing again at the enamel-dentin junction. Conversely, the concentrations of water, carbonate, magnesium, and sodium increase from the enamel surface to the enamel-dentin junction.

[0011] The water exists both in crystalline form, bound as a hydration shell to the apatite crystals, and loosely, fixed to the organic melt matrix. The loosely bound water can evaporate upon heating and be reabsorbed upon the addition of moisture. In this fluid flow, the melt acts as a molecular sieve, allowing ions to pass both out of and into the melt.

[0012] The apatite crystals have a hexagonal cross-section and are on average 169 nm long, 40 to 70 nm wide, and 26 nm thick. Although chemically they are also apatite-type calcium phosphates, they are much larger than crystallites of the same type but of different biological origin. Approximately 100 enamel crystallites are clustered together in cross-section, forming enamel prisms or rods that extend from the enamel-dentin junction to the surface. The crystallites in the core of the prisms are aligned with their longitudinal axis parallel to the longitudinal axis of the respective prism.

[0013] The entirety of the crystallites is embedded in a gel-like, organic matrix. The organic substances of the enamel are predominantly proteins, lipids, and traces of carbohydrates and organic acids. All crystallites are also surrounded by a hydration shell.

[0014] The prisms themselves are embedded in an interprismatic substance, which is also formed from melt crystallites. There are no differences in inorganic content between the prisms and the interprismatic zones; both consist of densely packed crystallites. The microscopically verifiable structuring into prismatic and non-prismatic components is simply a consequence of the crystal arrangement. The crystallites of the interprismatic substance form an almost right angle with the longitudinal axis of the prisms.

[0015] The enamel is only partially permeable to ions, water, dyes, and alcohol. It possesses a high modulus of elasticity and low tensile strength.

[0016] Both enamel and dentin are therefore highly complex structures that require different approaches to dental adhesive therapy. Fusion adhesion

[0017] The adhesion of composite resins to tooth enamel relies primarily on micromechanical retention and to a lesser extent on chemical adhesion. The principle of predominantly mechanical enamel bonding was first described in 1955 and is now a standard procedure for adhesive restorations in dental practice, known as "acid etching" or "enamel etching." Due to the varying solubility of the individual enamel prism structures, a microretentive etch pattern can be achieved using 30 to 40% phosphoric acid. A low-viscosity composite resin can penetrate this etched enamel pattern as a bonding agent, thus ensuring a strong bond with the filling composite through good interlocking. In the case of fissure sealing, the pattern created by the enamel etching is sufficient to achieve adequate bonding between the enamel and the sealing material, even without a bonding agent.

[0018] For small fillings in the enamel area, the micromechanical adhesion is so good that polymerization shrinkage can be completely compensated for. To avoid overloading the adhesive bond, larger fillings are applied in layers and cured separately to compensate for material shrinkage. Generally, the bond strength at the enamel is sufficient to prevent the formation of marginal gaps due to polymerization.

[0019] During the application of phosphoric acid, the enamel apatite is transformed into brushite, resulting in the formation of a non-specific retentive etching pattern whose structures are described as villi, tags, clefts, protrusions, or micropores. The enormous increase in surface area leads to a rise in surface energy and thus an improvement in the wettability of the etched enamel.

[0020] Optimal acid action is only achieved if the enamel area to be etched is completely free of plaque and tartar. A phosphoric acid solution of approximately 35% is typically used as the etching liquid, reducing the uppermost enamel layer by 5 to 10 µm and exposing the prismatic structure to a depth of 30 µm. Microscopically, three different types of etching patterns are observed: Priority demineralization of the central areas of the enamel prisms; demineralization of peripheral prism areas; simultaneous demineralization of the prism centers and the prism periphery.

[0021] The phosphoric acid should generally be left on for about 30 seconds and then thoroughly rinsed off. The tooth enamel is then dried.

[0022] For tooth restoration with highly viscous composite materials, a bonding agent is therefore necessary to ensure micromechanical anchorage to the enamel. This bonding agent is also referred to as a sealer, liner, primer, adhesive, or bonding agent. Dentin adhesion

[0023] The adhesive bonding of hydrophobic composite materials to dentin is considerably more difficult and complex compared to enamel due to its tubular microstructure, intrinsic moisture, and higher organic content. Nevertheless, numerous advancements have been made in this area, making it possible today to restore even dentin-bounded areas with composite.

[0024] The bonding mechanism of dentin adhesives is also primarily based on micromechanical anchorage with the dentin (so-called hybrid layer). The anchorage of the bonding agent is achieved through interlocking and cross-linking after the removal of organic and inorganic components from the dentin using acidic caustic preparations.

[0025] Several options are given for the mechanically retentive anchorage between the hydrophobic plastic and the moist dentin surface: Villi formation through polymerized resin in the tubules up to 50 µm in length; interlocking in microretentions of demineralized dentin; chaining with exposed collagen with inclusion of undissolved apatite, forming a hybrid layer.

[0026] The monomer mixtures, which penetrate the dentinal tubules, form plastic plugs after hardening; these are also known as "tags." The bonding of the "tags" to the demineralized peritubular dentin results in improved bond strength.

[0027] The penetration of the conditioned dentin surface with an adhesive results, after its hardening, in a so-called hybrid layer or "plastic-dentin interdiffusion zone".

[0028] This plastic-impregnated dentin layer is intended to contribute more strongly to dentin adhesion than the plastic tags in the dentinal tubules. Due to polymerization shrinkage, the plastic plugs do not line the tubule walls completely, and the presence of dentin fluid prevents incomplete polymerization of the plugs. The dentin fluid also prevents deep penetration of the plastic.

[0029] To a small extent, chemical components also appear to play a role in the adhesion mechanism. The reactive group on the bonding agent can interact with the inorganic components of dentin (especially Ca²⁺) as well as with the organic groups of collagen (amino and hydroxyl groups). Total Etch

[0030] Dentin etching, and thus the removal of the smear layer, is called conditioning. EDTA solutions, phosphoric acid (10 to 40%), maleic acid (10%), citric acid (10%), or nitric acid (2.5%) are used as etching agents. The conditioning agent should be rinsed off after a defined exposure time. Depending on the acid concentration, the smear layer is partially or completely dissolved. The additional demineralization of the dentin leads to the exposure of collagen fibers through the selective removal of calcium phosphates from the superficial dentin (1 to 7.5 µm). This network of collagen fibers has lost its mineralized support and, if the dentin dries too much, collapses like a dense bundle onto the underlying dentin. This is why nowadays only excess water is removed from the dentin surface, and the dentin is not completely dried with compressed air.This procedure, known as "moist bonding" or "wet bonding," uses the remaining water to keep the interfibrillar spaces in the collagen fiber network open. This allows subsequently applied hydrophilic monomers to penetrate the demineralized collagen network and, through subsequent polymerization, achieve micromechanical anchorage. Simultaneously, the tubular system is exposed and the peritubular dentin is etched.

[0031] A 35 to 40% phosphoric acid solution is typically used today, applied using the "total etch" technique. This involves simultaneous etching of both enamel and dentin. The acid should not remain on the dentin for longer than 15 to 20 seconds to avoid collagen denaturation and excessive dentin permeability. This would lead to reduced bond strength and could later have a detrimental effect on the pulp.

[0032] The current procedure involves applying the etching gel to the enamel. After a 15-second exposure time, the acid is then applied to the dentin, where it remains for another 15 seconds. The total 30-second exposure time on the enamel is necessary to achieve a sufficient etching pattern.

[0033] The first step in a clinically successful dental adhesive therapy is therefore the conditioning of enamel and dentin with an etching agent.

[0034] The acid was originally diluted with water to achieve the desired concentration. However, this creates a liquid solution that cannot be applied precisely. Furthermore, aqueous acid solutions have the disadvantage of running uncontrollably over the tooth surfaces and – if the dentist does not use a rubber dam for isolation – can easily damage the soft tissue of the mouth, potentially causing serious injury to patients.

[0035] To ensure that only the intended area is etched with pinpoint accuracy, the etchant should have a higher viscosity and ideally a thixotropic effect. Silica is often added to etchants to increase their viscosity, creating a gel. This allows for precise application of the etching gel and prevents it from running.

[0036] The term "gel" is sharply defined; the following applies to it: tan δ < 1 , where the loss factor tan δ = G" / G' (loss modulus / storage modulus) is.

[0037] In US patent 4,802,950 by TP Croll, entitled "Enamel bonding etching and procedure," a pasty etching gel is disclosed, comprising an aqueous solution with 35% to 50% phosphoric acid, pyrogenic silica, and abrasive silicon carbide particles. Here, the silica is used as a thickening agent to obtain a gel.

[0038] Silica is also used to produce an etching gel in US patents 6,753,001 B2 and 6,537,563 B2, respectively, by Pentron, entitled "Dental acid etching composition and method of use." These patents protect a composition consisting of an aqueous acid solution and a colloidal, nanoscale silica sol in an amount of 3 to 20% by weight, based on the total composition.

[0039] However, silica has the significant disadvantage of low water retention. This leads to water evaporation, which can increase the acid concentration and the viscosity and / or consistency of the etching agent over time. This inevitably causes problems in clinical practice. Therefore, it is advantageous to use an etching gel that does not contain silica.

[0040] Etching compositions without silica are already known from the prior art.

[0041] US Patent 5,954,996, "Dental etch and packaging therefore," by Centrix, claims a composition of an etching agent comprising an acid and anhydrous glycerin in an amount of 10 to 40 wt% based on the composition. Since this composition contains no excess water, the acid concentration and viscosity do not change over time. However, this etching agent is not a gel but a liquid. Furthermore, the question arises as to how this composition is supposed to produce an etching pattern in the absence of a protic solvent (water) when the dentist isolates the area with a rubber dam.

[0042] In US patent 2012 / 0161067 A1, issued by Far Eastern New Century Corporation and entitled "Dental etching gel composition and method of use thereof," carboxymethylcellulose is used to increase viscosity. The claimed composition consists of a 37% aqueous phosphoric acid solution and carboxymethylcellulose in amounts of 0.5 to 7% by weight. The viscosity of the carboxymethylcellulose is approximately 100 to 2000 cPs when dissolved in an aqueous solution at 1% by weight, and it exhibits an average degree of substitution of sodium salts in the molecular formula of approximately 21% to 33%. It would be expected that the acid would attack and degrade the cellulose over time.

[0043] US patent 6,312,667 B1, entitled "Methods of etching hard tissue in the oral environment," discloses an etching agent containing 17 to 40 wt% polyoxyalkylene polymer. The compositions exhibit an increase in viscosity at elevated temperatures.

[0044] US Patent 6,027,341, issued by Peridoc AB and entitled "Dental cavity conditioning," claims a composition in which dentin is etched with EDTA and enamel with phosphoric and / or citric acid. Preferably, the process is carried out with thickened compositions. For this purpose, cellulose and cellulose derivatives, proteins, or glycoproteins are used to increase viscosity. As above, it is expected that the thickening agents will be attacked and degraded by the acids over time.

[0045] In WO 2007 / 131725 A1 and EP 2 108 356 A1, hydrochloric acid-containing etching compositions for the treatment of enamel lesions are disclosed.

[0046] US 5,722,833 describes the conditioning of dental ceramic surfaces with hydrofluoric acid-containing etching compositions.

[0047] In WO 2015 / 142392 A1 entitled "Dental etching compositions comprising one or more dentin collagen cross-linking agents", dental etching compositions are disclosed. These may contain phosphoric acid, maleic acid, or citric acid as the acid component.

[0048] The aim of the present invention was therefore to provide storage-stable, highly effective etching gels that exhibit a sufficiently high viscosity to allow for precise application. Furthermore, the thickening agents used are intended to overcome the disadvantages of the prior art. Specifically, they should be acid-stable and possess a sufficiently high water retention capacity.

[0049] According to the invention, it was surprisingly found that storage-stable, silica-free, highly effective etching gels can be obtained when they contain certain types of urethane-urea compounds as thickening agents.

[0050] In particular, the task is solved by a comprehensive dental etching composition. A) Phosphoric acid in an amount of 10 to 45 wt.%, B) Water in an amount of 30 to 60 wt.%, C) One or more urethane-urea compounds in an amount of 5 to 20 wt.%, D) One or more water-miscible solvents in an amount of 0 to 20 wt.%, and E) Colouring agents in an amount of 0 to 5 wt.%, each with reference to the overall composition, characterized in that the urethane-urea compounds (C) correspond to the formula R 1< -OC(=O)-NH-R 2< -NH-C(=O)[-NH-R 3< -NH-C(=O)-NH-R 2< -NH-C(=O)] x -OR 1<, wherein R 1< represents an n-alkyl group with 4 to 22 C atoms, a branched alkyl group with 4 to 22 C atoms, an alkenyl group with 3 to 18 C atoms, a cycloalkyl group with 3 to 20 C atoms, an aryl group with 6 to 12 C atoms, an arylalkyl group with 7 to 12 C atoms, a group of the formula C m H 2m+1 (OC n H 2n ) p -, C m H 2m+1 (OOC-C v H 2v ) p - or R 5< -C 6 H 4 (OC n H 2n ) p - with m = 1 to 22, n = 2 to 4, p = 1 to 15, v = 4 or 5 and R 5< stands for an alkyl group with 1 to 12 C atoms, where different groups R 1< can be the same or different, R 2< for a branched or unbranched alkylene group with 4 to 22 C atoms, alkenylene group with 3 to 18 C atoms, alkynylene group with 2 to 20 C atoms,Cycloalkylene residue with 3 to 20 carbon atoms, cycloalkenylene residue with 3 to 20 carbon atoms, arylene residue with 6 to 12 carbon atoms or arylalkylene residue with 7 to 14 carbon atoms, where different residues R 2< can be the same or different, R 3< for , with R 4< = CH 3 or H, where different residues R 3< can be the same or different, and x represents an integer from 1 to 100.

[0051] Suitable urethane-urea compounds (C) and their syntheses are described in patent specifications EP 0 006 252 B1, EP 1 048 681 B1, EP 1 188 779 B1, EP 1 396 510 B1, EP 2 370 489 B1, EP 2 475 699 B1 and EP 3 328 909 B1.

[0052] In a particularly preferred embodiment R 1< for an n-alkyl group with 4 to 10 carbon atoms, a branched alkyl group with 4 to 10 carbon atoms, an alkenyl group with 3 to 10 carbon atoms, a cycloalkyl group with 3 to 10 carbon atoms, an aryl group with 6 to 12 carbon atoms, an arylalkyl group with 7 to 12 carbon atoms, a group of the formula C m H 2m+1 (OC n H 2n ) p -, C m H 2m+1 (OOC-C v H 2v ) p - or R 5< -C 6 H 4 (OC n H 2n ) p - with m = 1 to 10, n = 2 to 4, p = 1 to 15, v = 4 or 5 and R 5< for an alkyl group with 1 to 12 C atoms, preferably for an n-alkyl group with 4 to 10 C atoms, a branched alkyl group with 4 to 10 C atoms, a group of the formula C m H 2m+1 (OC n H 2n ) p - or C m H 2m+1 (OOC-C v H 2v ) p - with m = 1 to 10, n = 2 to 4, p = 1 to 15 and v = 4 or 5, wherein different groups R 1< can be the same or different, R 2< for or -(CH 2 ) w - with w = 2 to 10, preferably for or where different residues R 2< can be the same or different, R 3< for where different residues R 3< can be the same or different, and x for an integer from 1 to 20, preferably 1 to 10.

[0053] In the synthesis of the urethane-urea compounds (C), an alcohol is advantageously first reacted with a diisocyanate to form a monoadduct. R₁ < -OH + OCN-R₂ < -NCO → R₁ < -OC(=O)-NH-R₂ < -NCO

[0054] The reaction is preferably carried out in the absence of solvents. To obtain the monoisocyanate adduct as completely as possible, it is advantageous to use a 1.5- to 5-fold excess of diisocyanate, which can be distilled off again after the reaction has taken place.

[0055] The monoadduct is then reacted with a diamine to form the urethane-urea compound (C). 2 R 1< -OC(=O)-NH-R 2< -NCO + H 2 NR 3< -NH 2 → R 1< -OC(=O)-NH-R 2< -NH-C(=O)-NH-R 3< -NH-C(=O)-NH-R 2< -NH-C(=O)-OR 1<

[0056] If excess diisocyanate is still present, higher molecular weight urethane-urea compounds are formed. 2 R 1< -OC(=O)-NH-R 2< -NCO + (x-1) OCN-R 2< -NCO + x H 2 NR 3< -NH 2 → R 1< -OC(=O)-NH-R 2< -NH-C(=O)[-NH-R 3< -NH-C(=O)-NH-R 2< -NH-C(=O)] x -OR 1<

[0057] This reaction is preferably carried out in aprotic solvents, preferably DMSO, and can advantageously be performed in the presence of lithium salts, preferably lithium chloride. The proportion of urethane-urea compounds in the solution is preferably 10 to 75 wt.%, more preferably 40 to 60 wt.%.

[0058] In a preferred embodiment, the dental etching composition additionally comprises one or more water-miscible solvents (D).

[0059] The water-miscible solvents (D) are preferably selected from the group consisting of ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, 2-methylpropan-2-ol, glycerin, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, 2-butoxyethan-1-ol, DMSO and acetone, preferably selected from the group consisting of ethanol, propan-1-ol, propan-2-ol, glycerin, polyethylene glycol, polypropylene glycol and DMSO.

[0060] In a preferred embodiment, the dental etching composition additionally comprises colorant (E).

[0061] The colorants (E) are preferably selected from the group consisting of dyes, organic color pigments and inorganic color pigments, preferably from dyes, particularly preferably from phenothiazine dyes, and / or the colorants (E) are blue, green or red, preferably blue, colorants.

[0062] In a preferred embodiment, the dental etching composition comprises A) in a quantity of 30 to 42 wt.%, B) in a quantity of 40 to 60 wt.%, C) in a quantity of 5 to 15 wt.%, D) in a quantity of 1 to 15 wt.%, and E) in a quantity of 0.0001 to 1 wt.%, each in relation to the overall composition.

[0063] Since the presence of inorganic solids, in particular silicic acid as in the prior art, has the disadvantages described above, in a particular embodiment the dental etching composition is essentially free of pyrogenic silicic acid, preferably essentially free of silica particles, and particularly preferably essentially free of inorganic solids.

[0064] Essentially free of means that, within the limits of technical production possibilities, the content of pyrogenic silica, silica particles, or inorganic solids is so low that the described adverse effects do not occur. Preferably, therefore, "essentially free of" means a content of pyrogenic silica, silica particles, or inorganic solids of less than 1 wt.%, preferably less than 0.5 wt.%, and particularly preferably less than 0.1 wt.%, in each case based on the total composition. Compositions containing no pyrogenic silica, silica particles, or inorganic solids at all are especially preferred. Dissolved inorganic substances, in particular the lithium salts used in the synthesis of urethane-urea compounds, are not considered inorganic solids.

[0065] In a preferred embodiment, the dental etching composition contains no other components besides components (A), (B), (C), (D) and (E).

[0066] The dental etching compositions according to the invention are characterized by their gel-like nature and their viscosity, which is optimal for application. In particular, the dental etching compositions have a loss factor tan δ of less than 1 and / or a viscosity in the range of 0.1 to 200 Pa*s, preferably from 0.5 to 150 Pa*s, particularly preferably from 1 to 100 Pa*s, and most preferably from 1 to 50 Pa*s.

[0067] The values ​​for tan δ and viscosity refer to the measurement method described below and apply to both the evaluation point at the end of phase I and the evaluation point at the end of phase IV.

[0068] Furthermore, the dental etching compositions according to the invention are characterized by their good storage stability. The gel-like properties and the viscosity optimal for application are largely retained even during storage. In particular, the dental etching compositions preferably exhibit a loss factor tan δ of less than 1 and / or a viscosity in the range of 0.1 to 200 Pa*s, preferably 0.5 to 150 Pa*s, particularly preferably 1 to 100 Pa*s, and most preferably 1 to 50 Pa*s, even after storage for more than 6 months at 23 °C.

[0069] Particularly preferably, the dental etching compositions exhibit a loss factor tan δ of less than 1 and / or a viscosity in the range of 0.1 to 200 Pa*s, preferably 0.5 to 150 Pa*s, particularly preferably 1 to 100 Pa*s, and most preferably 1 to 50 Pa*s, even after storage for more than 12 months at 23 °C, preferably 18 months at 23 °C, and particularly preferably 24 months at 23 °C. After storage for 6 months at 37 °C, preferably 12 months at 37 °C, a loss factor tan δ of less than 1 and / or a viscosity in the range of 0.1 to 200 Pa*s, preferably from 0.5 to 150 Pa*s, particularly preferably from 1 to 100 Pa*s, most preferably from 1 to 50 Pa*s, and / or after storage for 12 months at 23 °C, preferably 18 months at 23 °C, particularly preferably 24 months at 23 °C, a viscosity that deviates by a maximum of ±50%, preferably by a maximum of ±35%, particularly preferably by a maximum of ±20%, from the viscosity before storage.

[0070] Another aspect of the present invention is the use of a dental etching composition, as described above, for etching the hard tissue of the tooth.

[0071] In a preferred embodiment, this use includes the steps i) optionally, drying of the teeth to be treated, preferably with a rubber dam, ii) application of the dental etching composition to the tooth structure to be treated, iii) allowing the dental etching composition to act in order to achieve an etching effect on the tooth structure, iv) rinsing off the dental etching composition, v) application of a dental primer and / or adhesive composition to the etched tooth structure, vi) optionally, polymerization of the dental primer and / or adhesive composition, vii) application of a dental restorative composition, and viii) polymerization of the dental restorative composition.

[0072] The above explanations regarding the preferred dental etching compositions also apply to their use.

[0073] Another aspect of the present invention is a dental etching composition, as described above, for use in a therapeutic method for etching the hard tissue of the teeth in the context of filling therapy.

[0074] In a preferred embodiment, this is a dental etching composition, as described above, for use in a therapeutic procedure comprising the steps i) optionally, drying the teeth to be treated, preferably with a rubber dam, ii) applying a dental etching composition according to any one of claims 1 to 11 to the tooth structure to be treated, iii) allowing the dental etching composition to act on the tooth structure to achieve an etching effect, iv) rinsing off the dental etching composition, v) applying a dental primer and / or adhesive composition to the etched tooth structure, vi) optionally, polymerizing the dental primer and / or adhesive composition, vii) applying a dental restorative composition, and viii) polymerizing the dental restorative composition.

[0075] The above explanations regarding preferred dental etching compositions also apply to their use in a therapeutic procedure.

[0076] Another aspect of the present invention is a kit containing a dental etching composition as described above, a dental primer and / or adhesive composition and optionally a dental restorative composition.

[0077] The foregoing explanations regarding preferred dental etching compositions also apply to a kit containing such etching composition. Examples Example 1A:

[0078] 0.5 mol (37.1 g) of 1-butanol are slowly added dropwise to 1.5 mol (261.3 g) of 2,4-toluene diisocyanate over 2 hours. The temperature is maintained between 50 and 55 °C. After the addition is complete, the mixture is stirred for a further 3 hours at 50 to 55 °C until the theoretical NCO content of 35.2% is reached. The excess diisocyanate is distilled off under vacuum (0.1 mbar) at 150 to 170 °C. The NCO content is 16.9%, and the free TDI content is <0.5%. Example 1B:

[0079] 0.5 mol (103.1 g) of triethylene glycol mono-n-butyl ether are slowly added dropwise to 1.5 mol (261.3 g) of 2,4-toluene diisocyanate over 2 hours. The temperature is maintained between 50 and 55 °C. After the addition is complete, the mixture is stirred for a further 3 hours at 50 to 55 °C until the theoretical NCO content of 28.8% is reached. The excess diisocyanate is distilled off under vacuum (0.1 mbar) at 150 to 170 °C. The NCO content is 11.0%, and the free TDI content is <0.5%. Example 1C:

[0080] 0.5 mol (175.0 g) of methoxypolyethylene glycol (MW 350) is slowly added dropwise to 1.5 mol (261.3 g) of 2,4-toluene diisocyanate over 2 hours. The temperature is maintained between 50 and 55 °C. After the addition is complete, the mixture is stirred for a further 3 hours at 50 to 55 °C until the theoretical NCO content of 24.1% is reached. The excess diisocyanate is distilled off under vacuum (0.1 mbar) at 150 to 170 °C. The NCO content is 8.0%, and the free TDI content is <0.5%. Example 1D:

[0081] 0.5 mol (275.0 g) of methoxypolyethylene glycol (MW 550) is slowly added dropwise to 1.5 mol (261.3 g) of 2,4-toluene diisocyanate over 2 hours. The temperature is maintained between 50 and 55 °C. After the addition is complete, the mixture is stirred for a further 3 hours at 50 to 55 °C until the theoretical NCO content of 19.6% is reached. The excess diisocyanate is distilled off under vacuum (0.1 mbar) at 150 to 170 °C. The NCO content is 5.8%, and the free TDI content is <0.5%. Example 1E:

[0082] 0.5 mol (175.0 g) of methoxypolyethylene glycol (MW 350) is slowly added dropwise to 2.0 mol (348.1 g) of 2,4-toluene diisocyanate over 2 hours. The temperature is maintained between 50 and 55 °C. After the addition is complete, the mixture is stirred for a further 3 hours at 50 to 55 °C until the theoretical NCO content of 28.1% is reached. The excess diisocyanate is distilled off under vacuum (0.1 mbar) at 150 to 170 °C. The NCO content is 8.0%, and the free TDI content is <0.5%. Example 1F:

[0083] 0.5 mol (175.0 g) of methoxypolyethylene glycol (MW 350) is slowly added dropwise to 1.0 mol (174.2 g) of 2,4-toluene diisocyanate over 2 hours. The temperature is maintained between 50 and 55 °C. After the addition is complete, the mixture is stirred for a further 3 hours at 50 to 55 °C until the theoretical NCO content of 18.0% is reached. The excess diisocyanate is distilled off under vacuum (0.1 mbar) at 150 to 170 °C. The NCO content is 8.0%, and the free TDI content is <0.5%. Example 1G:

[0084] 0.5 mol (375.4 g) of 1-butanol are slowly added dropwise to 1.5 mol (375.4 g) of diphenylmethane-4,4'-diisocyanate over 2 hours. The temperature is maintained between 50 and 55 °C. After the addition is complete, the mixture is stirred for a further 3 hours at 50 to 55 °C until the theoretical NCO content of 25.5% is reached. The excess diisocyanate is distilled off under vacuum (0.1 mbar) at 150 to 170 °C. The NCO content is 13.0%, and the free MDI content is <0.5%. Example 1H:

[0085] 0.5 mol (37.1 g) of 1-butanol are slowly added dropwise to 1.5 mol (252.3 g) of 1,6-hexamethylene diisocyanate over 2 hours. The temperature is maintained between 50 and 55 °C. After the addition is complete, the mixture is stirred for a further 3 hours at 50 to 55 °C until the theoretical NCO content of 36.3% is reached. The excess diisocyanate is distilled off under vacuum (0.1 mbar) at 150 to 170 °C. The NCO content is 17.3%, and the free HMDI content is <0.5%. Table 1: Examples 1A to 1D Example 1A 1B 1C 1D Diisocyanat 2,4-Toluene diisocyanate 2,4-Toluene diisocyanate 2,4-Toluene diisocyanate 2,4-Toluene diisocyanate alcohol 1-Butanol Triethylene glycol monobutyl ether Methoxypolyethylene glycol 350 Methoxypolyethylene glycol 550 Diisocyanate / alcohol ratio 3 : 1 3 : 1 3 : 1 3 : 1 NCO content 16.9% 11.0% 8.0% 5.8% Table 1 (continued): Examples 1E to 1H Example 1E 1F 1G 1H Diisocyanat 2,4-Toluene diisocyanate 2,4-Toluene diisocyanate Diphenylmethane 4,4'-diisocyanate 1,6-Hexamethylene diisocyanate alcohol Methoxypolyethylene glycol 350 Methoxypolyethylene glycol 350 1-Butanol 1-Butanol Diisocyanate / alcohol ratio 4 : 1 2 : 1 3 : 1 3 : 1 NCO content 8.0% 8.0% 13.0% 17.3% Example 2A:

[0086] In 175 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Then, 124.2 g of Example 1A are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2B:

[0087] In 224 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Then, 190.2 g of Example 1B are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2C:

[0088] In 313 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Subsequently, 262.1 g of Example 1C are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2D:

[0089] In 413 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Subsequently, 362.1 g of Example 1D are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2E:

[0090] In 313 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Subsequently, 262.1 g of Example 1E are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2F:

[0091] In 313 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Subsequently, 262.1 g of Example 1F are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2G:

[0092] In 213 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Subsequently, 162.2 g of Example 1G are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2H:

[0093] In 172 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Subsequently, 121.2 g of Example 1H are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2I:

[0094] In 313 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,2-xylylenediamine are dissolved at 80 °C. Subsequently, 262.1 g of Example 1C are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2J:

[0095] In 313 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,4-xylylenediamine are dissolved at 80 °C. Subsequently, 262.1 g of Example 1C are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2K:

[0096] In 315 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 35.6 g (0.25 mol) of 1,3-bis(aminomethyl)cyclohexane are dissolved at 80 °C. Subsequently, 262.1 g of Example 1C are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2L:

[0097] 27.6 g (0.4 mol) of lithium nitrate and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved in 324 g of DMSO at 80 °C. Then, 262.1 g of Example 1C are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 50%. Example 2M:

[0098] In 209 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Subsequently, 262.1 g of Example 1C are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 40%. Example 2N:

[0099] In 470 g of DMSO, 17.0 g (0.4 mol) of lithium chloride and 34.1 g (0.25 mol) of 1,3-xylylenediamine are dissolved at 80 °C. Subsequently, 262.1 g of Example 1C are added over one hour. After the addition, the mixture is stirred for a further 30 minutes at 80 °C and then cooled to room temperature. The proportion of dissolved solids in the resulting urethane-urea solution is 60%. Table 2: Examples 2A to 2D Example 2A 2B 2C 2D Monoadduct 1A 1B 1C 1D Diamine 1,3-Xylylenediamine 1,3-Xylylenediamine 1,3-Xylylenediamine 1,3-Xylylenediamine Lithium salt LiCl LiCI LiCI LiCI solids content 50% 50% 50% 50% Table 2 (continued): Examples 2E to 2H Example 2E 2F 2G 2H Monoadduct 1E 1F 1G 1H Diamine 1,3-Xylylenediamine 1,3-Xylylenediamine 1,3-Xylylenediamine 1,3-Xylylenediamine Lithium salt LiCl LiCI LiCI LiCI solids content 50% 50% 50% 50% Table 2 (continued): Examples 2I to 2L Example 2I 2J 2K 2L Monoadduct 1C 1C 1C 1C Diamine 1,2-Xylylenediamine 1,4-Xylylenediamine 1,3-Bis(aminomethyl)cyclohexane 1,3-Xylylenediamine Lithium salt LiCl LiCl LiCl LiNO 3 solids content 50% 50% 50% 50% Table 2 (continued): Examples 2M to 2N Example 2M 2N Monoadduct 1C 1C Diamine 1,3-Xylylenediamine 1,3-Xylylenediamine Lithium salt LiCl LiCl solids content 40% 60% Example 3A:

[0100] In a beaker, 41.2 g of 85% phosphoric acid, 1.0 g of PEG-400, and 0.01 g of methylene blue were dissolved in 39.4 g of demineralized water while stirring. Then, 18.4 g of the DMSO solution from Example 2A were added portionwise while stirring and the mixture was stirred for a further 30 minutes at room temperature. Examples 3B to 3N:

[0101] Analogous to Example 3A, etching gels 3B to 3N were prepared, using the DMSO solutions from Examples 2B to 2N instead of the DMSO solution from Example 2A. Example 30:

[0102] In a beaker, 41.2 g of 85% phosphoric acid, 1.0 g of glycerol, and 0.01 g of methylene blue were dissolved in 39.4 g of demineralized water while stirring. Then, 18.4 g of the DMSO solution from Example 2A were added portionwise while stirring and the mixture was stirred for a further 30 minutes at room temperature. Example 3P:

[0103] In a beaker, 41.2 g of 85% phosphoric acid, 2.0 g of ethanol, and 0.01 g of methylene blue were dissolved in 38.4 g of demineralized water while stirring. Then, 18.4 g of the DMSO solution from Example 2A were added portionwise while stirring and the mixture was stirred for a further 30 minutes at room temperature. Example 3Q:

[0104] In a beaker, 41.2 g of 85% phosphoric acid and 0.01 g of methylene blue were dissolved in 40.4 g of demineralized water with stirring. Then, 18.4 g of the DMSO solution from Example 2A were added portionwise with stirring and the mixture was stirred for a further 30 minutes at room temperature. Example 3R:

[0105] In a beaker, 41.2 g of 85% phosphoric acid, 2.5 g of PEG-400, 4.5 g of glycerol, and 0.01 g of methylene blue were dissolved in 39.4 g of demineralized water while stirring. Then, 12.4 g of the DMSO solution from Example 2A were added portionwise while stirring and the mixture was stirred for a further 30 minutes at room temperature. Example 3S:

[0106] In a beaker, 41.2 g of 85% phosphoric acid, 1.0 g of PEG-400, 1.5 g of glycerol, and 0.01 g of methylene blue were dissolved in 41.3 g of demineralized water while stirring. Then, 15.0 g of the DMSO solution from Example 2A were added portionwise while stirring and the mixture was stirred for a further 30 minutes at room temperature. Example 3T:

[0107] In a beaker, 41.2 g of 85% phosphoric acid, 1.0 g of glycerol, and 0.01 g of methylene blue were dissolved in 36.8 g of demineralized water with stirring. Then, 22.0 g of the DMSO solution from Example 2A were added portionwise with stirring and the mixture was stirred for a further 30 minutes at room temperature. Example 3U:

[0108] In a beaker, 41.2 g of 85% phosphoric acid, 0.5 g of glycerol, and 0.01 g of methylene blue were dissolved in 33.9 g of demineralized water with stirring. Then, 24.4 g of the DMSO solution from Example 2A were added portionwise with stirring and the mixture was stirred for a further 30 minutes at room temperature. Table 3: Examples 3A to 3Q 3A to 3N 3O 3P 3Q (A)* 1< H3PO4 * 1< 35.02 35.02 35.02 35.02 (B)* 2< Water* 2< 45.57 45.57 44.57 46.57 (C)* 3< Urethane-urea compound* 3< 9.20 9.20 9.20 9.20 (D)* 4< PEG-400 1.00 Glycerin 1.00 Ethanol 2.00 DMSO* 4< 9.20 9.20 9.20 9.20 (E) Methylene blue 0.01 0.01 0.01 0.01 In total 100.00 100.00 100.00 100.00 * 1< Since 85% phosphoric acid was used in the examples, only the actual proportion of phosphoric acid is given here under (A). * 2< In addition to the water used, the proportion of water from the phosphoric acid is also given under (B). * 3< Since examples 2 involve a solution of the urethane-urea compound, only the actual proportion of the urethane-urea compound is given under (C). * 4< In addition to any other water-miscible solvents, the proportion of the solvent in the urethane-urea solution is also given under (D). Table 3 (continued): Examples 3R to 3U 3R 3S 3T 3U (A)* 1< H3PO4 * 1< 35.02 35.02 35.02 35.02 (B)* 2< Water* 2< 45.57 47.47 41.97 40.07 (C)* 3< Urethane-urea compound* 3< 6.20 7.50 11.00 12.20 (D)* 4< PEG-400 2.50 1.00 Glycerin 4.50 1.50 1.00 0.50 DMSO* 4< 6.20 7.50 11.00 12.20 (E) Methylene blue 0.01 0.01 0.01 0.01 In total 100.00 100.00 100.00 100.00 Comparison example 4A:

[0109] In a beaker, 10.0 g of gum arabic and 0.01 g of methylene blue were dissolved in 48.8 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. No thickening effect occurred. The solution remained thin. Comparison example 4B:

[0110] In a beaker, 20.0 g of gum arabic and 0.01 g of methylene blue were dissolved in 38.8 g of demineralized water while stirring. Then, 41.2 g of 85% phosphoric acid were added while stirring, and the mixture was stirred for a further 30 minutes at room temperature. No thickening effect occurred. The solution remained thin. Comparison example 4C:

[0111] In a beaker, 2.0 g of xanthan gum and 0.01 g of methylene blue were dissolved in 56.8 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. The viscosity is 3.0 Pa*s. During storage at 23 °C, the viscosity slowly increases to 4.2 Pa*s within 6 months. Significant gas evolution occurs after storage of just one month at 23 °C. 4D comparison example:

[0112] In a beaker, 5.0 g of xanthan gum and 0.01 g of methylene blue were dissolved in 53.8 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. The viscosity is 6.0 Pa*s. During storage at 23 °C, the viscosity slowly increases to 8.3 Pa*s within 6 months. Significant gas evolution occurs after storage of just one month at 23 °C. Comparison example 4E:

[0113] In a beaker, 10.0 g of polyvinyl alcohol and 0.01 g of methylene blue were dissolved in 48.8 g of demineralized water while stirring. Then, 41.2 g of 85% phosphoric acid were added while stirring, and the mixture was stirred for a further 30 minutes at room temperature. There was hardly any thickening effect; the solution remained thin. Comparison example 4F:

[0114] In a beaker, 20.0 g of polyvinyl alcohol and 0.01 g of methylene blue were dissolved in 38.8 g of demineralized water while stirring. Then, 41.2 g of 85% phosphoric acid were added while stirring, and the mixture was stirred for a further 30 minutes at room temperature. There was hardly any thickening effect; the solution remained thin. 4G comparison example:

[0115] In a beaker, 30.0 g of polyvinyl alcohol and 0.01 g of methylene blue were dissolved in 28.8 g of demineralized water while stirring. Then, 41.2 g of 85% phosphoric acid were added while stirring, and the mixture was stirred for a further 30 minutes at room temperature. The viscosity is 10.0 Pa*s. The material cannot be applied well to the prepared tooth surface. The movement during application causes it to become liquid and "flow" off the tooth. Comparison example 4H:

[0116] In a beaker, 2.5 g of hydroxyethylcellulose and 0.01 g of methylene blue were dissolved in 56.3 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. Only a slight thickening effect occurred. The solution is relatively thin. Comparison example 4I:

[0117] In a beaker, 5.0 g of hydroxyethylcellulose and 0.01 g of methylene blue were dissolved in 53.8 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. The viscosity is 6.5 Pa*s. During storage at 23 °C, the viscosity decreases to 2.5 Pa*s within one month. Comparison example 4J:

[0118] In a beaker, 20.0 g of glycerol and 0.01 g of methylene blue were dissolved in 38.8 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. No thickening effect occurred. The solution remained thin. 4K comparison example:

[0119] In a beaker, 40.0 g of glycerol and 0.01 g of methylene blue were dissolved in 18.8 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. No thickening effect occurred. The solution remained thin. Comparison example 4L:

[0120] In a beaker, 0.01 g of methylene blue was dissolved in 58.8 g of glycerol with stirring. Then, 41.2 g of 85% phosphoric acid was added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. No thickening effect occurred. The solution remained thin. Comparison example 4M:

[0121] In a beaker, 2.5 g of carboxymethylcellulose and 0.01 g of methylene blue were dissolved in 56.3 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. The viscosity is 2.5 Pa*s, but it decreases noticeably during storage, and the gel becomes more liquid. Comparison example 4N:

[0122] In a beaker, 5.0 g of carboxymethylcellulose and 0.01 g of methylene blue were dissolved in 53.8 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring, and the mixture was stirred for a further 30 minutes at room temperature. The viscosity is 8.2 Pa*s, but it decreases noticeably during storage, and the gel becomes more liquid. Comparative example 40:

[0123] In a beaker, 0.01 g of methylene blue was dissolved in 58.8 g of demineralized water with stirring. Then, 41.2 g of 85% phosphoric acid were added with stirring. Next, 5.0 g of Aerosil A200 was added and dispersed with an Ultra Turrax for 5 minutes. The viscosity is 10.4 Pa*s, but increases noticeably during storage and the gel thickens. Comparison example 4P:

[0124] In a beaker, 0.01 g of methylene blue was dissolved in 8.8 g of demineralized water with stirring. Then, 50.0 g of Snowtex ST-O (20% colloidal silica in water; particle size 10–20 nm) and subsequently 41.2 g of 85% phosphoric acid were added with stirring and the mixture was stirred for a further 30 minutes at room temperature. The viscosity is 8.8 Pa*s, but increases noticeably during storage and the gel thickens. Table 4: Comparison examples 4A to 4D 4A 4B 4C 4D (A)* 1< H3PO4 * 1< 35.02 35.02 35.02 35.02 (B)* 2< Water* 2< 54.97 44.97 62.97 59.97 (X) Gum arabic 10.00 20.00 Xanthan gum 2.00 5.00 (E) Methylene blue 0.01 0.01 0.01 0.01 In total 100.00 100.00 100.00 100.00 Table 4 (continued): Comparison examples 4E to 4H 4E 4F 4G 4H (A)* 1< H3PO4 * 1< 35.02 35.02 35.02 35.02 (B)* 2< Water* 2< 54.97 44.97 34.97 62.47 (X) Polyvinyl alcohol 10.00 20.00 30.00 Hydroxyethylcellulose 2.50 (E) Methylene blue 0.01 0.01 0.01 0.01 In total 100.00 100.00 100.00 100.00 Table 4 (continued): Comparison examples 4I to 4L 4I 4J 4K 4L (A)* 1< H3PO4 * 1< 35.02 35.02 35.02 35.02 (B)* 2< Water* 2< 59.97 44.97 24.97 6.18 (X) Hydroxyethylcellulose 5.00 (D) Glycerin 20.00 40.00 58.79 (E) Methylene blue 0.01 0.01 0.01 0.01 In total 100.00 100.00 100.00 100.00 Table 4 (continued): Comparison examples 4M to 4P 4M 4N 4O 4P (A)* 1< H3PO4 * 1< 35.02 35.02 35.02 35.02 (B)* 2,5< Water* 2.5< 62.47 59.97 59.97 54.97 (X) Carboxymethylcellulose 2.50 5.00 pyrogenic silica 5.00 colloidal silica* 6< 10.00 (E) Methylene blue 0.01 0.01 0.01 0.01 In total 100.00 100.00 100.00 100.00 * 1< Since 85% phosphoric acid was used in the examples, only the actual proportion of phosphoric acid is given here under (A). * 2< In addition to the water used, the water content from the phosphoric acid is also given under (B). * 5< When using the aqueous dispersion of colloidal silica, the water content from the dispersion is also given under (B). * 6< Under (X), only the SiO₂ content is given for the colloidal silica. Shear bond strength:

[0125] Shear bond strength tests were performed according to ISO 29022:2013. Bovine incisors were embedded in an epoxy matrix in the form of a cylinder with a diameter d = 2.5 cm. Subsequently, the enamel and dentin surfaces were exposed. The tooth surfaces were standardized by coarse grinding with P120 grit sandpaper (125 ± 1 µm) followed by fine grinding with P400 grit sandpaper (35 ± 1 µm). The prepared tooth surface was cleaned of contaminants under running deionized water and then dewatered by a short burst of oil- and water-free compressed air immediately before the application of the etching agent. The teeth must not be over-dried to prevent morphological changes to the tooth structure. The etching agent is applied directly from the syringe over a wide area onto the hard tooth structure and left for 30 seconds (enamel) or 30 seconds (ceramic).Leave the dentin undisturbed for 15 seconds. Then rinse under running water for several seconds. The resulting etched tooth is then cleaned of excess water with a gentle / brief jet of oil- and water-free compressed air and used while still moist. The adhesive (Futurabond U, VOCO GmbH) is applied to the prepared tooth surface and massaged into it for 20 seconds. Solvents contained in the adhesive are removed by blowing with a jet of oil- and water-free compressed air for 5 seconds. Light curing is then performed for 10 seconds (Celalux 2, VOCO GmbH, 420–490 nm, 1000 W / cm²). After curing, the embedded tooth specimen is placed in a composite screw clamp including a mold (according to ISO 29022:2013 - FA. Ultradent Products, South Jordan). The mold is placed on the tooth surface, checked for a sufficient fit, and fixed with the appliance screws.The composite (GrandioSO A1, VOCO GmbH) is applied to the bonding surface in the recess of the insert mold using a packing instrument and then light-cured for 10 seconds (Celalux 2, VOCO GmbH, 420 - 490 nm, 1000 W / cm 2< ).

[0126] The composite specimen is removed from the composite clamp and stored in water at 37 °C for 24 ± 2 h. The shear strength is determined immediately after removal from the water. For this purpose, the composite specimens are subjected to a shear test on a universal testing machine (ZwickRoell GmbH & Co. KG, Ulm) at a transverse main velocity of 1.0 ± 0.1 mm / min and a preload of 1 N until failure. The shear strength in MPa is calculated as the quotient of the failure force in N and the bond area in mm². Viscosity:

[0127] The viscosity was determined using a Physica MCR 301 rheometer (Anton Paar) in an oscillation test (plate / plate) at 23 °C. The plate diameter was 50 mm and the gap spacing was 1 mm. The viscosity measurement method comprises four consecutive steps.

[0128] In Phase I of the measurement, measurements are taken for five minutes (measurement point duration 5 s) at a deformation of 0.1% and an oscillation frequency of 10 Hz. The last point of Phase I is used for evaluation.

[0129] In phase II of the measurement, measurements are taken for 60 s (measurement point duration 1 s) at an oscillation frequency of 10 Hz, whereby the deformation is increased by 5 percentage points per second from 0.1% to 300%.

[0130] In phase III of the measurement, measurements are taken again for 60 s (measurement point duration 1 s) at a deformation of 0.1% and an oscillation frequency of 10 Hz.

[0131] In phase IV of the measurement, measurements continue for 4 minutes (measurement point duration 4 s) at a deformation of 0.1% and an oscillation frequency of 10 Hz, but with a longer measurement point duration. The last point of phase IV is used for evaluation.

[0132] The evaluation point of phase I describes the viscosity in the resting state, and the evaluation point of phase IV describes the viscosity after shear stress (i.e., after application to the tooth surface). Table 5: Example 3A 3B 3C 3D 3E 3F 3G Liability (Dentin) [MPa] 33.2 31.8 32.2 31.7 32.5 32.3 33.3 Liability (melt) [MPa] 35.2 34.5 34.7 34.7 35.0 35.1 35.1 Viscosity (I) [Pa*s] 2.5 2.5 2.6 2.4 2.7 2.3 2.3 Viscosity (IV) [Pa*s] 2.5 2.5 2.6 2.4 2.7 2.2 2.3 tan δ (I) 0.89 0.83 0.85 0.82 0.90 0.90 0.83 tan δ (IV) 0.89 0.84 0.85 0.83 0.91 0.91 0.84 Viscosity (I) (6 months, 23 °C) [Pa*s] 2.5 2.5 2.5 2.4 2.7 2.2 2.2 Viscosity (IV) (6 months, 23 °C) [Pa*s] 2.4 2.5 2.5 2.3 2.6 2.1 2.2 tan δ (I) (6 months, 23 °C) 0.90 0.89 0.86 0.87 0.85 0.93 0.90 tan δ (IV) (6 months, 23 °C) 0.90 0.90 0.88 0.90 0.87 0.96 0.90 Table 5 (continued): Example 3H 3I 3J 3K 3L 3M 3N Liability (Dentin) [MPa] 32.3 31.1 30.7 33.6 31.2 33.1 32.1 Liability (melt) [MPa] 35.2 35.5 34.6 34.8 35.5 34.5 34.9 Viscosity (I) [Pa*s] 2.4 2.1 2.4 2.3 2.6 2.8 2.9 Viscosity (IV) [Pa*s] 2.4 2.0 2.3 2.3 2.5 2.7 2.8 tan δ (I) 0.88 0.89 0.87 0.87 0.81 0.79 0.88 tan δ (IV) 0.90 0.90 0.89 0.88 0.83 0.81 0.90 Viscosity (I) (6 months, 23 °C) [Pa*s] 2.4 2.0 2.3 2.3 2.6 2.7 2.8 Viscosity (IV) (6 months, 23 °C) [Pa*s] 2.3 2.0 2.3 2.2 2.5 2.6 2.7 tan δ (I) (6 months, 23 °C) 0.88 0.90 0.89 0.88 0.82 0.80 0.88 tan δ (IV) (6 months, 23 °C) 0.89 0.91 0.91 0.89 0.85 0.81 0.89 Table 5 (continued): Example 3O 3P 3Q 3R 3S 3T 3U Liability (Dentin) [MPa] 31.3 31.6 32.7 30.1 32.4 32.1 30.0 Liability (melt) [MPa] 34.9 35.3 35.4 33.9 33.8 34.1 33.1 Viscosity (I) [Pa*s] 1.8 1.3 1.1 1.9 2.1 3.5 4.6 Viscosity (IV) [Pa*s] 1.7 1.3 1.1 1.8 2.0 3.2 4.3 tan δ (I) 0.91 0.97 0.99 0.90 0.87 0.75 0.91 tan δ (IV) 0.92 0.98 0.99 0.92 0.89 0.78 0.92 Viscosity (I) (6 months, 23 °C) [Pa*s] 1.7 1.4 1.2 1.8 2.0 3.4 4.4 Viscosity (IV) (6 months, 23 °C) [Pa*s] 1.7 1.4 1.2 1.1 1.9 3.2 4.1 tan δ (I) (6 months, 23 °C) 0.91 0.95 0.96 0.90 0.86 0.79 0.91 tan δ (IV) (6 months, 23 °C) 0.92 0.96 0.98 0.91 0.88 0.83 0.92 Table 6: Comparative example 4A 4B 4C 4D 4E 4F 4G Liability (Dentin) [MPa] 14.2 15.1 17.3 16.8 15.3 12.8 11.5 Liability (melt) [MPa] 16.3 18.4 20.4 19.1 17.7 14.3 12.3 Viscosity (I) [Pa*s] 0.2 0.3 3.0 6.0 0.6 0.8 10.0 Viscosity (IV) [Pa*s] 0.2 0.3 2.9 5.8 0.6 0.8 1.1 tan δ (I) 1.50 1.39 0.88 0.82 1.28 1.22 1.50 tan δ (IV) 1.50 1.39 0.90 0.85 1.29 1.23 1.50 Viscosity (I) (6 months, 23 °C) [Pa*s] nb nb 4.2 8.3 nb nb nb Viscosity (IV) (6 months, 23 °C) [Pa*s] nb nb 4.1 8.0 nb nb nb tan δ (I) (6 months, 23 °C) nb nb 0.81 0.75 nb nb nb tan δ (IV) (6 months, 23 °C) nb nb 0.84 0.79 nb nb nb Table 6 (continued): Comparative example 4H 4I 4J 4K 4L 4M 4N Liability (Dentin) [MPa] 20.4 20.8 nb nb nb 18.4 19.7 Liability (melt) [MPa] 22.3 22.5 nb nb nb 19.8 20.5 Viscosity (I) [Pa*s] 1.2 6.5 0.2 0.2 0.3 2.5 8.2 Viscosity (IV) [Pa*s] 1.1 6.2 0.2 0.2 0.3 2.3 7.9 tan δ (I) 1.12 0.91 1.51 1.48 1.41 0.97 1.12 tan δ (IV) 1.14 0.94 1.51 1.48 1.41 0.99 1.14 Viscosity (I) (6 months, 23 °C) [Pa*s] 0.9 1.8 nb nb nb 1.1 1.8 Viscosity (IV) (6 months, 23 °C) [Pa*s] 0.9 1.4 nb nb nb 1.0 1.6 tan δ (I) (6 months, 23 °C) 1.18 1.02 nb nb nb 1.13 1.03 tan δ (IV) (6 months, 23 °C) 1.19 1.05 nb nb nb 1.14 1.05 Table 6 (continued): Comparative example 4O 4P Liability (Dentin) [MPa] 28.9 25.3 Liability (melt) [MPa] 30.7 28.4 Viscosity (I) [Pa*s] 60.4 58.8 Viscosity (IV) [Pa*s] 58.9 58.4 tan δ (I) 0.65 0.78 tan δ (IV) 0.88 0.83 Viscosity (I) (6 months, 23 °C) [Pa*s] 22.4 15.7 Viscosity (IV) (6 months, 23 °C) [Pa*s] 20.1 15.3 tan δ (I) (6 months, 23 °C) 0.54 0.69 tan δ (IV) (6 months, 23 °C) 0.68 0.75

Claims

1. Dental etching composition comprising A) phosphoric acid, in an amount of 10% to 45% by weight, B) water, in an amount of 30% to 60% by weight, C) one or more urethane-urea compounds, in an amount of 5% to 20% by weight, D) one or more solvents miscible with water, in an amount of 0% to 20% by weight, E) colourant, in an amount of 0% to 5% by weight, based in each case on the overall composition, characterized in that the urethane-urea compounds (C) conform to the formula         R1-O-C(=O)-NH-R2-NH-C(=O)[-NH-R3-NH-C(=O)-NH-R2-NH-C(=O)]x-OR1 in which R1 is an n-alkyl radical having 4 to 22 carbon atoms, a branched alkyl radical having 4 to 22 carbon atoms, an alkenyl radical having 3 to 18 carbon atoms, a cycloalkyl radical having 3 to 20 carbon atoms, an aryl radical having 6 to 12 carbon atoms, an arylalkyl radical having 7 to 12 carbon atoms, a radical of the formula CmH2m+1(O-CnH2n)p-, CmH2m+1(OOC-CvH2v)p- or R5-C6H4(O-CnH2n)p- with m = 1 to 22, n = 2 to 4, p = 1 to 15, v = 4 or 5, and R5 is an alkyl radical having 1 to 12 carbon atoms, where different R1 radicals may be the same or different, R2 is a branched or unbranched alkylene radical having 4 to 22 carbon atoms, alkenylene radical having 3 to 18 carbon atoms, alkynylene radical having 2 to 20 carbon atoms, cycloalkylene radical having 3 to 20 carbon atoms, cycloalkenylene radical having 3 to 20 carbon atoms, arylene radical having 6 to 12 carbon atoms or arylalkylene radical having 7 to 14 carbon atoms, where different R2 radicals may be the same or different, R3 is or with R4 = CH3 or H, where different R3 radicals may be the same or different, and x is an integer from 1 to 100.

2. Dental etching composition according to Claim 1, wherein the urethane-urea compounds (C) conform to the formula         R1-O-C(=O)-NH-R2-NH-C(=O)[-NH-R3-NH-C(=O)-NH-R2-NH-C(=O)]x-OR1 in which R1 is an n-alkyl radical having 4 to 10 carbon atoms, a branched alkyl radical having 4 to 10 carbon atoms, an alkenyl radical having 3 to 10 carbon atoms, a cycloalkyl radical having 3 to 10 carbon atoms, an aryl radical having 6 to 12 carbon atoms, an arylalkyl radical having 7 to 12 carbon atoms, a radical of the formula CmH2m+1(O-CnH2n)p-, CmH2m+1(OOC-CvH2v)p- or R5-C6H4(O-CnH2n)p- with m = 1 to 10, n = 2 to 4, p = 1 to 15, v = 4 or 5, and R5 is an alkyl radical having 1 to 12 carbon atoms, preferably an n-alkyl radical having 4 to 10 carbon atoms, a branched alkyl radical having 4 to 10 carbon atoms, a radical of the formula CmH2m+1(O-CnH2n)p- or CmH2m+1(OOC-CvH2v)p- with m = 1 to 10, n = 2 to 4, p = 1 to 15 and v = 4 or 5, where different R1 radicals may be the same or different, R2 is or -(CH2)w- with w = 2 to 10, preferably where different R2 radicals may be the same or different, R3 is where different R3 radicals may be the same or different, and x is an integer from 1 to 20, preferably 1 to 10.

3. Dental etching composition according to any of the preceding claims, wherein the water-miscible solvents (D) are selected from the group consisting of ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, 2-methylpropan-2-ol, glycerol, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, 2-butoxyethan-1-ol, DMSO and acetone, preferably selected from the group consisting of ethanol, propan-1-ol, propan-2-ol, glycerol, polyethylene glycol, polypropylene glycol and DMSO.

4. Dental etching composition according to any of the preceding claims, wherein the colourants (E) are selected from the group consisting of dyes, organic colour pigments and inorganic colour pigments, preferably from dyes, more preferably from phenothiazine dyes, and / or wherein the colourants (E) are blue, green or red, preferably blue, colourants.

5. Dental etching composition according to any of the preceding claims, comprising A) in an amount of 30% to 42% by weight, B) in an amount of 40% to 60% by weight, C) in an amount of 5% to 15% by weight, D) in an amount of 1% to 15% by weight and E) in an amount of 0.0001% to 1% by weight, based in each case on the overall composition.

6. Dental etching composition according to any of the preceding claims which is essentially free of fumed silica, preferably essentially free of silica particles, more preferably essentially free of inorganic solids, and / or which does not contain any further constituents apart from A), B), C), D) and E).

7. Dental etching composition according to any of the preceding claims which has a loss factor tan δ of less than 1 and / or a viscosity in the range from 0.1 to 200 Pa*s, preferably from 0.5 to 150 Pa*s, more preferably from 1 to 100 Pa*s, most preferably from 1 to 50 Pa*s, and which preferably even after storage at 23°C for 6 months has a loss factor tan δ of less than 1 and / or a viscosity in the range from 0.1 to 200 Pa*s, preferably from 0.5 to 150 Pa*s, more preferably from 1 to 100 Pa*s, most preferably from 1 to 50 Pa*s, wherein loss factor tan δ and viscosity are measured as described in the description.

8. Dental etching composition according to any of Claims 1 to 7 for use in a therapeutic method for etching the hard substance of the tooth in the course of filling treatment, preferably in a therapeutic method comprising the steps of i) optionally desiccating the teeth to be treated, preferably with a dental dam, ii) applying a dental etching composition according to any of Claims 1 to 7 to the hard substance of the tooth to be treated, iii) allowing a contact time of the dental etching composition to achieve an etching effect on the hard substance of the tooth, iv) rinsing off the dental etching composition, v) applying a dental primer composition and / or adhesive composition to the etched hard substance of the tooth, vi) optionally polymerizing the dental primer composition and / or adhesive composition, vii) applying a dental restoration composition and viii) polymerizing the dental restoration composition.

9. Kit comprising - a dental etching composition according to any of Claims 1 to 7, - a dental primer composition and / or adhesive composition and - optionally a dental restoration composition.