Dental restoration parts kit

Abstract

The present invention relates to a kit for dental restoration comprising an aqueous activator solution containing polyacrylic acid having a molecular weight of 100,000-1,000,000 g / mol, the concentration of polyacrylic acid in the solution being 1-30 mg / l, and a lining material comprising 20-80% by weight of a dental resin and 20-80% by weight of an ion-releasing material containing at least one of calcium, phosphate and zinc, based on the total weight of the lining material.

Description

Technical Field

[0001] The present invention relates to dental restorations and methods for producing dental restorations.

Background Art

[0002] Tooth decay, also known as dental caries or cavities, is the destruction of teeth by acids produced by bacteria. The treatment of tooth decay is performed by removing the carious lesion and replacing it with a restorative material. In dentin infected with tooth decay, the organic matrix is irreversibly damaged, but in deeper carious lesions affecting dentin, the calcification in the healthy organic matrix is reduced, and there is a possibility of repair and remineralization.

[0003] The preparation of minimally invasive cavities by manually removing carious lesions using a dentin excavator is currently one of the recommended approaches to avoid the generation of aerosols and droplets during restorative treatment. The minimally invasive approach ultimately aims to minimize the excavation of tooth tissue and instead promote the restoration and repair of tooth tissue. The slow progression of tooth decay actually enables restorative intervention and the restoration of the mineralized structure after excavating the infected layer.

[0004] Various approaches can be classified into classical and non-classical approaches and are applied to the remineralization process. In the classical approach, the remineralization of dentin is based on the epitaxial growth of residual microcrystals, and when dentin is stored in a solution rich in calcium ions and phosphate ions, it functions as a nucleation site for the precipitation of calcium phosphate minerals. However, recent studies have shown that such an approach may result in incomplete and non-functional remineralization of dentin. In classical remineralization approaches, remineralization of the outer fibers of the dentin collagen matrix occurs without mineralization of the inner fiber portion of the collagen. This is thought to be due to the size of the apatite crystals formed during this process without any control of size and orientation. As a result, non-classical approaches have been proposed as alternative remineralization techniques in vitro, aiming to achieve hierarchical biomimetic remineralization of the organic matrix of dentin.

[0005] To perform a biomimetic non-classical remineralization process, two things are required. First, the use of synthetic substitutes for specific dentin matrix proteins that play important roles during the biomimetic remineralization process (formation and stabilization of amorphous calcium phosphate). The second is a cavity liner used as a source of calcium and phosphate. The known solution is to treat the cleaned surface of the carious lesion with a cavity liner and then apply a restorative material. Summary of the Invention Problems to be Solved by the Invention

[0006] Therefore, an object of the present invention is to develop an easy-to-use dental restoration product that can promote remineralization of dentin. Advantageously, this product will result in a strong and complete restoration. A further advantage is that the product is antibacterial, i.e., it limits the growth of bacteria. Means for Solving the Problems

[0007] (Summary of the Invention) The present invention is defined by the features of the independent claims. Some specific embodiments are defined by the dependent claims. According to one aspect of the present invention, a dental restoration kit is provided as follows. - An aqueous activator solution containing polyacrylic acid having a molecular weight of 100,000 to 1,000,000 g / mol, wherein the concentration of polyacrylic acid in the solution is 1 to 30 mg / l, and - A lining material, based on the total weight of the lining material, comprising 20 to 80% by weight of a dental resin and 20 to 80% by weight of an ion-releasing material containing at least one of calcium, phosphate, and zinc, and a dental restoration kit comprising the lining material.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0013] In the specification, the term "antimicrobial" means that the substance kills microorganisms or inhibits their growth, with little or no damage to the host. The term "remineralisation of dentin" refers to the natural repair process of non-carious lesions where calcium, phosphate ions, and in some cases fluoride ions, deposit in the crystal voids of demineralised enamel. "Remineralisation" contributes to the restoration of strength and function within the tooth structure. The term "release rate" means the amount of ions released from a sample within a given time. In this context, a "surface modifier" is a component or compound whose main purpose is to activate the mineralisation of the tooth being restored. The term "dental resin" refers to a monomer mixture or polymer that is suitable for dental use, i.e., biocompatible and having sufficient strength, and capable of polymerization and / or crosslinking.

[0014] In the context of this application, the average length of the fibres is determined as follows. The fibres are photographed with a stereomicroscope (or scanning electron microscope) at a magnification of 6.5 times. The photograph is then processed with an Image-J processing program to determine the length of the fibres. The total number of fibres included in the calculation is 500. The fibres are then divided into a plurality of sections at 0.1 mm intervals according to their lengths. The fibre lengths at each 0.1 mm interval are summed. The average fibre length is taken as the value when the lengths of the short and long fibres are considered equal. This measurement method is described in "Mechanical properties of fiber reinforced restorative composite with two distinguished fiber length distribution, Journal of the mechanical behavior of biomedical materials 60 (2016) 331-338, Section 2.5, page 333". The same determination method can be used to determine the average size of the particles, and the measured dimension is the maximum dimension of the particles. The diameter of the fiber (i.e., the diameter of the cross-section) can also be determined by this method if not provided by the manufacturer. Typically the same results are obtained with different measurement methods, and one of the possible measurement methods for particle size is disclosed in ISO13320:2009. Most commonly, the average particle size is provided by the manufacturer, in particular.

[0015] According to an aspect of the present invention, a kit for dental restoration is provided as follows. - An aqueous activator solution containing polyacrylic acid having a molecular weight of 100,000 to 1,000,000 g / mol, wherein the concentration of polyacrylic acid in the solution is 1 to 30 mg / l, and - A lining material, comprising a dental restoration kit including a lining material containing 20 to 80% by weight of a dental resin and 20 to 80% by weight of an ion-releasing material containing at least one of calcium, phosphate, and zinc, based on the total weight of the lining material.

[0016] The kit thus provides a combination of a dentin activator solution and a lining material that functions as a strong cavity liner and contains additives having the ability to remineralize (e.g., by calcium and / or phosphate) and / or antibacterial (e.g., by zinc). The ion-releasing material of the lining material is in a form that can be released from the material, and some examples are shown below. In some cases, the lining material may be in the form of a flowable composite material, preferably bioactive. Without being bound by any theory, it is believed that the activator solution negatively charges the dentin surface containing collagen fibers, attracts ions from the ion-releasing material, and stabilizes the formation of hydroxyapatite crystals. The combination of materials and their properties was selected based on mechanical properties, chemical properties, and handling properties.

[0017] The aqueous activator solution (also called the activation solution) is usually composed mostly or solely of water and polyacrylic acid (PAA). It is also possible to use another polyelectrolyte other than polyacrylic acid or to use a small amount of additional components. For example, the activator solution can further contain 10-methacryloyloxydecyl dihydrogen phosphate (MDP). When used, it is usually used at a concentration of 0.8 to 7.5 mg / ml. According to experimental data, the concentrations of 0.4 and 8.3 mg / ml still have little effect, but in this context, the range of 0.8 to 7.5 mg / ml is considered optimal. The effect of MDP is to increase the initial bond and improve the durability of the bonded restoration. Optionally, known adhesion promoters such as 4-methacryloxyethyl trimellitic anhydride (4-META), N-(2-hydroxy-3-((2-methyl-1-oxo-2-propenyl)oxy)propyl)-N-tolyl glycine (NTG-GMA), bis-(-)-nor-mephedinol (BisMEP), pyromellitic acid bis(glyceryl dimethacrylate) (PMDGM), or 1,3-glycerol dimethacrylate / maleate (GDMA maleate), or any mixture thereof, can be used instead of or in addition to MDP.

[0018] According to one embodiment, the concentration of MDP is 1.0 to 6.5 mg / ml. According to another embodiment, the concentration of MDP is 2.0 to 5.5 mg / ml. The concentration of MDP may be, for example, from 0.8, 0.9, 1.0, 1.2, 1.5, 1.7, 2.0, 2.2, 2.5, 2.7, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 or 7.0 mg / ml up to a maximum of 1.2, 1.5, 1.7, 2.0, 2.2, 2.5, 2.7, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, or 7.5 mg / ml.

[0019] The molecular weight of PAA used in the activator solution is 100,000 - 1,000,000 g / mol. The molecular weight is the weight-average molecular weight and is usually provided by the manufacturer of PAA. PAA with a weight-average molecular weight measured by gas chromatography within the above range is suitable for this application. According to one embodiment, the molecular weight of polyacrylic acid (PAA) is 250,000 - 600,000 g / mol. According to one embodiment, it has been found in this context that a molecular weight of 10,000 g / mol is too small and a molecular weight of 4,000,000 g / mol is too large. The molecular weight of PAA may be, for example, from 100000, 120000, 150000, 200000, 250000, 300000, 350000, 400000, 450000, 500000, 550000, 600000, 650000, 700000, 750000, 800000, 850000 or 900000 g / mol up to 150000, 200000, 250000, 300000, 350000, 400000, 450000, 500000, 550000, 600000, 650000, 700000, 750000, 800000, 850000, 900000, 950000 or 1000000 g / mol.

[0020] The concentration of polyacrylic acid in the solution is 1 - 30 mg / l. According to one embodiment, the concentration of PAA in the solution is 5 - 20 mg / l. The concentration may be, for example, from 1, 3, 5, 7, 10, 12, 15, 18, 20, 22, 25 or 28 mg / l to 3, 5, 7, 10, 12, 15, 18, 20, 22, 25, 28 or 30 mg / l.

[0021] As demonstrated in the following examples section, both the selected molecular weight and the selected concentration of PAA are relevant to the final result.

[0022] Typically, the activator solution is suitable for use as a drilling solution or as a surface modifier in tooth restoration. The drilling solution and the surface modifier, and their uses are known per se, and the kit contains an activator solution in a form suitable for any of these uses. Typically, the viscosity of the drilling solution is slightly lower than that of the surface modifier.

[0023] This kit contains a lining material comprising 20 - 80 wt% dental resin and 20 - 80 wt% ion - releasing material based on the total weight of the lining material. The amount of dental resin may be, for example, from 20, 25, 30, 35, 40, 45, 50, 55, 60, 65 or 70 wt% to 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80 wt%. The amount of ion - releasing material may be, for example, from 20, 25, 30, 35, 40, 45, 50, 55, 60, 65 or 70 wt% to 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80 wt%. Examples of various amounts are shown below.

[0024] According to one embodiment, the ion - releasing material contains calcium and phosphate. According to another embodiment, the ion - releasing material contains calcium and zinc. According to yet another embodiment, the ion - releasing material contains phosphate and zinc. According to a preferred embodiment, the ion - releasing material contains calcium, phosphate, and zinc. According to another preferred embodiment, the ion - releasing material contains calcium, phosphate, zinc and titanium. The ion-releasing material may include additional materials such as bioactive glass, aluminum, and / or titanium. The ion-releasing material can be selected from hydroxyapatite, carbonate apatite, calcium carbonate, bioactive glass, zinc oxide-containing glass, calcium aluminosilicate glass, titanium oxide-containing glass, and mixtures thereof.

[0025] According to one embodiment, the composition of the ion-releasing material, based on the total weight of the ion-releasing material, - 35 to 55 wt% of carbonate apatite, - 2 to 10 wt% of calcium carbonate, and - 40 to 60 wt% of ZnO-containing glass, is as follows.

[0026] According to another embodiment, the composition of the ion-releasing material, based on the total weight of the ion-releasing material, - 40 to 50 wt% of carbonate apatite, - 4 to 8 wt% of calcium carbonate, and - 45 to 55 wt% of ZnO-containing glass, is as follows.

[0027] The release rates of various ions from the ion-releasing material can be controlled in various ways. One way to control the release rate is the degree of crystallization. Typically, if the ion-releasing material is apatite, carbonate, and / or glass and is highly crystallized (such as having a crystallinity of 20% or more or 70% or more depending on the material), it may be rather inert, i.e., the ions are released slowly. The crystallinity suitable for the desired release rate depends on the selected material, which can vary widely. However, for most materials, the material needs to be amorphous to release ions quickly. The release rate also depends on the pH of the environment. Therefore, in the ion release material, it is possible and advantageous to combine at least two different materials having different release rates. In this case, the material with a high release rate releases ions quickly, while the material with a low release rate releases ions more slowly, thus releasing ions over a longer period.

[0028] The lining material is preferably suitable for use as a liner material or a base material during dental restoration. That is, the use of liner and base materials is itself known, as well as the necessary properties such as viscosity and wetness. The difference between the liner material and the base material is known to those skilled in the art and can be summarized as follows: the liner material is applied as a thin layer (typically 0.5 - 1 mm, or thinner than 0.5 mm) at the bottom of the cavity to be restored, while the base material is applied in a slightly thicker layer (usually 2 - 4 mm).

[0029] The lining material also includes dental resins, which are typically selected from the group consisting of methyl methacrylate, ethyl methacrylate, n - butyl methacrylate, isobutyl methacrylate, 2 - ethylhexyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, morpholinoethyl methacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diurethane dimethacrylate, 2,2 - bis(4-(2 - hydroxy - 3 - methacryloxy)phenyl)propane, acrylic acid, epoxy, bisphenol A - glycidyl methacrylate (BisGMA), urethane dimethacrylate (UDMA), semi - crystalline polyether (PEX), trimethylolpropane ethoxylate triacrylate, and mixtures thereof.

[0030] The kit may further include a dental restoration resin. Dental restoration resins are typically selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, morpholinoethyl methacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diurethane dimethacrylate, 2,2-bis(4-(2-hydroxy-3-methacryloxy)phenyl)propane, acrylic acid, epoxy, bisphenol A-glycidyl methacrylate (BisGMA), urethane dimethacrylate (UDMA), semi-crystalline polyether (PEX), trimethylolpropane ethoxylate triacrylate, and mixtures thereof. Thus, the dental restoration resin may be the same as or different from the resin of the lining material. The dental restoration resin may also include a filler such as any of those listed below.

[0031] The resin in the lining material and / or the dental restoration resin may be a compound disclosed in International Publication No. WO 2020 / 035321, the content of which is incorporated herein by reference, particularly with respect to the production of this compound. Thus, the compound can have the following general formula (I).

[0032] [Chemical formula] (I) Here, n = 1, R = NH, and R’ is (Ia) or (Ib)

[0033] [Chemical formula] (Ia) Here, k is 2 or 3,

[0034] [Chemical formula] (Ib) Here, n = 2, R = O, and R' is (Ic) or (Id).

[0035]

Chemical Structure

[0036]

Chemical Structure

[0037]

Chemical Structure

[0038]

Chemical Structure

[0039] The lining material may further contain a filler. Such fillers include, for example, components such as silicon (Si), calcium (Ca), phosphorus (P), barium (Ba), magnesium (Mg), potassium (K), titanium (Ti), fluorine (F), strontium (Sr), zinc (Zn), cerium (Ce), niobium (Nb), or other compounds of the above elements, bioactive or partially reactive glass ionomer fillers, coloring pigments, inert ceramics, inert silica, hydroxylapatite (HA) or other calcium phosphates, Al2O3, ZrO2, Ag, zerogel, bioactive glass or filler particles containing functional bioactive molecules or therapeutic active molecules, antigens, antibiotics, disinfectants, radiopaque materials, organic acids such as maleic acid, polyacrylic acid, etc. Any of these fillers may be incorporated into the dental restorative resin.

[0040] According to a preferred embodiment, the lining material further contains an inert filler. The fillers are typically selected from E-glass fibers, S-glass fibers, and mixtures thereof. Any of these fillers may be incorporated into the dental restorative resin.

[0041] According to one embodiment, the relative amounts of the ion-releasing material, dental resin, and inert filler in the lining material, based on the total weight of the lining material, - 30 to 50 wt% of the ion-releasing material, - 30 to 50 wt% of the dental resin, and - 10 to 30 wt% of the inert filler.

[0042] According to another embodiment, the relative amounts of the ion-releasing material, dental resin, and inert filler in the lining material, based on the total weight of the lining material, - 35 to 45 wt% of the ion-releasing material, - 35 to 45 wt% of the dental resin, and - 15 to 25 wt% of the inert filler.

[0043] The filler may be particulate or fibrous. Particles include, for example, spheres and very short fibers (where the fiber length is at most twice its diameter), as well as whiskers, i.e., those significantly shorter than short fibers having a length of less than 50 μm. In the case of fibrous fillers, the fiber length ranges from 80 μm to 300 μm (micrometers). Optionally, the average fiber length ranges from 100 to 300 μm. For example, the average length of the filler fibers may be from 100, 120, 150, 170, 200, 220, 230, or 250 μm to 120, 150, 180, 200, 210, 220, 230, 250, 280, or 300 μm. Optionally, in a preferred embodiment, the average length of the fibers in the material ranges from 150 to 250 μm. The average maximum dimension of the particulate filler may be, for example, from 0.3 to 25 μm. For irregular particles, the diameter of the particles in the filler is the maximum diameter of the particles. The diameter may be from 0.3, 0.5, 1, 5, 7, 10, 13, 15, 17, 20, or 22 μm to 1, 5, 7, 10, 13, 15, 17, 20, 22, or 25 μm. These suitable sizes also apply to the above ion-releasing materials.

[0044] When using this kit, the dentist first prepares the cavity to be restored. During drilling, the activating solution can be used as a drilling solution (also called a rinsing solution). Alternatively, it can be applied as a surface modifier, i.e., applied to the inner surface of the cavity (either the entire inner surface of the cavity or only the bottom of the cavity) as the first step after drilling and rinsing. Subsequently, the liner material is applied as a liner material or a base material, followed by curing of the liner or base material, usually by light curing. The third step is further to apply a dental restoration (usually a resin) and cure the resin. Thus, the dental restoration covers the lining material, thereby preventing the leaching of ions into the patient's mouth.

[0045] The embodiments of the present invention disclosed are not limited to the specific structures, process steps, or materials disclosed herein, and it should be understood that they extend to their equivalents, as would be recognized by those skilled in the relevant art. Also, it should be understood that the terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting.

[0046] Furthermore, the described features, structures, or characteristics can be combined in any suitable way in one or more embodiments. In the specification, many specific details such as examples of length, width, shape, etc. are provided to provide a complete understanding of the embodiments of the present invention.

[0047] In this document, the verbs "consisting of" and "comprising" are used as open limitations that do not exclude functions not mentioned or require their presence. The features described in the dependent claims can be freely combined with each other unless otherwise explicitly stated. Furthermore, it should be understood that the use of "a" or "an" throughout this document, i.e., the singular form, does not exclude the plural form.

[0048] (Detailed Description of the Drawings) FIG. 1 schematically shows the background theory of the present invention according to one embodiment. In the figure, the ion-emitting material is schematically shown as region 1, which is shown as containing various ions that can be emitted. Since the dentin (indicated by reference numeral 2) has been treated with an activating solution, its surface attracts Ca 2+ ions (as an example of ions). Due to this difference in charge, it is considered that the movement of ions from the ion-emitting material to the dentin is induced. FIGS. 2A and 2B show the preparation of samples, which will be described in more detail below. FIGS. 3A - 33 show the results of tests performed on the samples, which will be described in more detail in relation to the parts of the following examples.

Examples

[0049] According to this specification, several different samples were prepared and compared with samples prepared using commercially available products. Various measurements described below were performed.

[0050] Adjustment of Samples The activator solution was prepared by mixing distilled water (Grade III) and polyacrylic acid (PAA) from Sigma-Aldrich (St. Louis, Missouri, USA) having a predetermined molecular weight. Different molecular weights (5000 g / mol, 450000 g / mol, and 4000000 g / mol) and concentrations (10 mg / L, 20 mg / L, 2 g / L, and 500 g / L) of PAA in water were tested. 10-Methacryloyloxydecyl dihydrogen phosphate (MDP, manufactured by Fluorochem, Hadfield, UK) at the concentrations shown in Table 2 below was used.

[0051] The lining material was prepared by mixing the components together. The following components were used, and each size and molecular weight were provided by the manufacturer. - E-glass fibers with a diameter of 6 μm and a length distribution of 50 - 200 μm (90 wt% of the fibers are within this range), manufactured by GC Dental - Calcium phosphate particles with a diameter of approximately 10 μm, Cytrans® manufactured by GC Dental - Calcium carbonate particles with a primary particle size of 200 nm (the material forms clusters, and the primary particle size was provided by the manufacturer), manufactured by Shirai - A ZnO-containing reactive glass powder mixture with an average particle size of 0.7 μm, containing glass from Schott (85 wt% of the mixture) and GC Dental (15 wt% of the mixture, the glass powder used in Caradyne®) - Silica filler: BaAlSiO2 filler particles from Schott (diameter 0.7 μm) (UltraFine, GM27884, manufactured by Schott, Landshut, Germany) - Various resin mixtures containing the following components -BisGMA (Bisphenol A - Glycidyl Methacrylate), manufactured by Esstech Inc. (Essington, Pennsylvania, USA) -TEGDMA (Diethylene Glycol Dimethacrylate, Triethylene Glycol Dimethacrylate), manufactured by Esstech Inc. (Essington, Pennsylvania, USA) -UDMA (Urethane Dimethacrylate), manufactured by Sigma - Aldrich Co. (St. Louis, Missouri, USA)

[0052] The dental disks used in the tests were prepared as follows. First, the occlusal surfaces of extracted healthy third molars were wet - ground under water cooling using an automatic grinding machine with 500 grit, 300 rpm (Struers Rotopol - 11) (obtained from the Dental Education Clinic, University of Turku, Finland, USA). After that, as shown in Figure 2A, disks (2 mm thick) were cut from the teeth in the transverse direction of the longest dimension of the teeth, and five similar samples were created for each experiment. In Figure 2A, tooth 3 and two cutting lines 4 are shown. Demineralization of the dentin disks was simulated by acid - etching (with 37% phosphoric acid for 20 seconds).

[0053] For the remineralization test, the disks (shown by reference number 5 in Figure 2B) were surface - treated (i.e., rinsed) with an activator solution (see Table 3) or not (i.e., rinsed with ordinary water; as control sample C0) before being immersed in a simulated body fluid (SBF) prepared according to ISO 23317 (2014) for 7 days.

[0054] To evaluate the interface between dentin and the current lining material, dentin disks (prepared as above) were first treated with PAA (450000 g / mol, 10 mg / l in distilled water), and then interface samples were prepared by treating them with the lining material according to Example 30 (Ex30) (see Table 1 below). Since the lining material is fluid, it was applied to the dentin disk using a handheld dental plastic instrument and then photocured for 20 seconds (emission wavelength range: 430 - 480 nm, irradiance: approximately 1600 mW / cm 2 ). Thereafter, the samples were immersed in SBF for 2 weeks.

[0055] To observe the interface between a given commercial material and dentin, comparative interface samples were also prepared. The dentin disks were prepared as described above using phosphoric acid etching without using an activator solution. The commercial material was applied to the dentin disks according to the manufacturer's instructions, and the cured (depending on the material) comparative samples were stored in SBF for 2 weeks. For Comparative Example C1, Fuji II LC from GC Dental was used; for Comparative Example C2, Fuji IX from GC Dental was used; for Comparative Example C3, Activa-Liner from Pulpdent Corp. in the United States was used; and for Comparative Example C4, Caredyne from GC Dental was used.

[0056] In accordance with ISO 4049:2019, samples with a diameter of 10 mm and a thickness of 1 mm were prepared to test the ion release (or dissolution) from this material and the control samples. This material was placed in a mold and cured for 20 seconds.

[0057] The ion release samples according to this specification had different component contents as listed in Table 1. The amounts of the components of the lining material are weight percentages relative to the total weight of the lining material. The resins used were BisGMA / TEGDMA (50 / 50) for Exp24, 25, 26, 27, 28, and 30, and UDMA / TEGDMA (70 / 30) for Exp31. To test the dissolution of calcium into water from the disk samples in 24 hours, a control ion release sample C5 consisting of BisGMA / TEGDMA (50 / 50) and a silica filler was used.

[0058]

Table 1

[0059] For the flexural strength test, the same samples as the above samples Exp24, 25, 26, 27, 28 and 30 were used (i.e., prepared according to ISO 4049:2019). Furthermore, comparative samples for flexural strength (five similar samples each) were also used. The comparative samples for flexural strength were prepared using Fuji Lining LC as C6, manufactured by GC Dental, TheraCal LC as C7, manufactured by Bisco Dental, USA, Activa-Liner as C8, manufactured by Pulpdent Corp., USA, and Ultra-Blend plus as C9, manufactured by Ultra Dent, USA. Furthermore, flexural strength comparative samples were prepared using the same materials as comparative samples C1 - C4. That is, Fuji II LC, manufactured by GC Dental, was used for comparative example C10, Fuji IX, manufactured by GC Dental, was used for comparative example C11, and Caredyne, manufactured by GC Dental, was used for comparative example C12.

[0060] The bonding performance (i.e., shear bond strength) between the material according to this specification and dentin was also evaluated after different dentin surface treatments. The bonding performance was also evaluated by adding different weight percentages of 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate) to the PAA solution.

[0061] First, dentin disks were prepared as described above, except that etching was used only for one bonding sample and one comparative bonding sample (samples S2a and S2b in Table 2 below).

[0062] For each treatment, bonding samples (samples S1a - S8a) were prepared by applying the lining material according to Example Exp30 above, and comparative bonding samples (samples S1b - S8b) were prepared using a commercially available flowable composite material (manufactured by GC, G-aenial Injectable) as described below. Each sample and comparative sample were stored in water overnight, and the adhesive strength was measured the next day.

[0063] For the measurement of the bonding performance, the occlusal surface of the extracted tooth was wet-polished (using an automatic grinding machine, 500 grit, 300 rpm under water cooling, Struers Rotopol-11) to create a flat dentin surface. Subsequently, the tooth was individually attached to an acrylic block (2.5 cm in diameter) using a low-temperature-curing auto-polymerizing acrylic resin, Palapress (Palapress; manufactured by Heraus Kulzer, Wehrheim, Germany).

[0064] Using a transparent polyethylene mold with an inner diameter of 3.6 mm, a lining material (by Exp30 above) or a comparative material (G-aenial Injectable, manufactured by GC Dental) was applied to the dentin substrate while incrementing by 2 mm each time to form a protrusion with a diameter of 3.6 mm. The lining material and the comparative material were photo-polymerized twice for 20 seconds each from the side and the top surfaces at full thickness using a manual photo-curing unit (Elipar S10). The test specimens were stored in water (37 °C) for 1 day before the test.

[0065] The adhesion performance test was carried out on samples prepared using different dentin surface treatments according to Table 2.

[0066]

Table 2

[0067] The fracture toughness was also tested using a single-edge notched beam test specimen (2.5×5×25 mm 3 ) in accordance with the ISO20795-2:2013 standard method (the adaptation was only for the sample size, and the other tests were in accordance with the standard). By using a specially ordered split mold made of stainless steel, the test piece could be taken out without applying force. The accurately designed slots were created to extend to the middle of the height at the center of the mold, and the center position of the notch and the crack length (x) could be optimized to half of the height of the test piece. The materials tested were Example Exp30 and the above comparative tests C1, C2, C3, and C4. This material was inserted once into the mold placed on a glass slide covered with a Mylar strip. Before polymerization or curing, a sharp crack located at the center was generated by inserting a steel blade with a straight edge into the existing slot of the mold. The polymerization of the resin composite material of Exp30 was carried out for 20 seconds in five separate overlapping parts. Before exposure to the polymerization light, the upper side of the mold was covered with Mylar strips and glass slides from both sides of the blade. When taken out of the mold, each test piece was polymerized on the opposite side as well. The application and polymerization of the commercially available materials (C1 - C4) were carried out according to the manufacturer's instructions. The test pieces (n = 6) of each material were stored in a dry state at 37°C for 24 hours before the test.

[0068] One of the additional samples, C14, was prepared to test the effect of cellulose nanocrystals (NCC) on the reduction of aerosol emission during the use of the activator solution. In this example, the activator solution was prepared by mixing distilled water (Grade III) and polyacrylic acid (PAA) manufactured by Sigma - Aldrich (St. Louis, MO, USA) with a molecular weight of 450000 g / mol until the PAA concentration in water reached 10 mg / L. Furthermore, 10 - Methacryloyloxydecyl dihydrogen phosphate (MDP) manufactured by Fluorochem Ltd, Hadfield, UK was added to the activation solution in an amount of 5 mg / ml. The activating solution was thickened with 1 wt% of cellulose nanocrystals (NCC), NovaWire-CNC-T, manufactured by Novarials, based on the total weight of the solution. This sample was further used in the shear bond test described below using a light-curing G-aenial Injectable (stub diameter 3.6 mm) manufactured by GC. Thus, sample C14 is equivalent to sample C13b except for the use of NCC.

[0069] Test methods The chemical properties were estimated by measuring the degree of monomer conversion (DC%) by FT-IR spectroscopy using the method described in "Ferracane et al., Academy of Dental Materials guidance-Resin composites: Part II-Technique sensitivity (handling, polymerization, dimensional changes), Dental Materials 33 (2017) 1171-1191".

[0070] Furthermore, ion release due to pH changes was measured by atomic absorption spectrometry (AAS) using an ion-selective electrode (ISE) and ISO 9917-1:2007.

[0071] Scanning electron microscopy (SEM / EDS) was used to evaluate the properties of the dentin surface (both the mineralized control sample C0 and the mineralized sample rinsed with the activator solution) after immersion in SBF for 1, 2, 3, and 7 days.

[0072] The interface between the material according to the present specification and dentin was tested by horizontally bisecting the disk after storing the interface sample in SBF for 2 weeks and using SEM / EDS and chemical mapping. The same was done for the comparative interface samples C1-C5.

[0073] The following tools and reagents were used to measure the solubility of calcium and zinc from the samples. The AAS (Atomic Absorption Spectrometry) values were measured using an A Analyst 400 atomic absorption spectrometer, serial number 201S8090503, manufactured by PerkinElmer Life and Analytical Sciences, Shelton, Connecticut, USA. The ISE (Ion Selective Electrode) values were measured using an Orion ionplus Sure-Flow Electrode Body 9700BNWP, VV1-11811, Thermo Scientific, USA, while the liquid for the electrode was Orion ionplus Filling Solution, A optimum Results, Orion 900061, 60 ml, LOT UV1, P / N 223228-A01, Thermo Fisher Scientific, Chelmsford, USA. The calcium standard used was calcium standard 0.1M Ca 2+ , 475 ml of Orion ionplus Application solution, Orion 922006, (deionized water H2O CAS 7732-18-5, calcium chloride CaCl2 CAS 10043-52-4), Exp 11 / 2018, LOT: UP1, P / N: 02480-A03, CML: 922006, manufactured by Thermo Fisher Scientific, USA, was used. The ISA used was Calcium ISA Ionic Strength Adjuster, Orion ionplus Application Solution, 475 ml, Orion 932011, LOT: UP1, P / N: 702555-A03, CML: 932011, manufactured by Thermo Fisher Scientific, USA. The pH meter used was the PHM 220 LAB pH METER, 657R005N035, Radiometer Copenhagen, MeterLab TM, Radiometer Analytical S.A., France. As the buffer solution, AVS with a pH of 4 (Titrinorm, VWR Chemicals, 00168, 100 ml, 32095.184, LOT 19B194007, VWR International S.A.S. Fontenay-sous-Bois, France) was used. As other buffer solutions (phosphate buffers), those with a pH of 7 (+ / -0.02 (20°C): AVS Titrinorm, VWR Chemicals, 00152, 100 ml, 32096.187, LOT 19G124120, VWR International bvba Leuven, Belgium) and those with a pH of 10 (AVS Titrinorm, VWR Chemicals, 00093, 100 ml, 32040.185, LOT 19G104115, VWR International bvba Leuven, Belgium) were used together.

[0074] The mechanical properties were estimated by measuring the flexural strength before and after aging in water at 100°C for 16 hours using the LRX model, manufactured by Lloyd Instruments Ltd and ISO standard 4049:2019.

[0075] The measurement of the adhesion performance (shear adhesion strength) was carried out as follows. The samples and comparative samples prepared as described above were first attached and fixed to the mounting jig and then placed on the shear adhesion strength test assembly. The test was performed at room temperature (23 ± 1°C) using a universal testing machine (LRX, Lloyd Instruments), and the data was recorded using PC software (Nexygen, Lloyd Instruments). The shear rod was placed parallel to the prepared flat bonding site. A circular perforation with a diameter of 4.1 mm was formed in the metal blade, and the composite material was passed through until the metal blade was positioned at the interface between the lining material or commercial material and dentin. Thereafter, a load was applied at a crosshead speed of 1.0 mm / min and a span length of 10 mm until the test piece broke. The bond strength was calculated by dividing the maximum load (N) at failure by the bond area (mm 2 ) and recorded in megapascals (MPa). The test setup is shown in Figures 28A and 28B.

[0076] Additional tests were also conducted. The dentin surface disks were prepared without etching the surface, i.e., simply bur cut with a high-speed handpiece and prepared under ordinary water coolant solution or the above-mentioned activator solution (PAA molecular weight 450,000 g / mol, concentration 10 mg / l). The disks were stored in SBF for one week and then evaluated by SEM / EDS as described above. The results are shown in Figures 16 - 20.

[0077] The fracture toughness was also tested at a crosshead speed of 1.0 mm / min using a universal material testing machine in a three-point bending mode on samples prepared as described above. The fracture toughness (FT) was calculated using the following formula.

[0078]

Equation

[0079] Here, P is the maximum load in kilonewtons (kN), L is the span length (2 cm), B is the thickness of the test piece in centimeters (cm), W is the width (depth) of the test piece in cm, x depends on a geometric function, and in a / W, a is the crack length in cm. The value of x is given in ASTM E399 - 12.

[0080] Results According to Experiment 1, the monomer conversion rate (DC%) measured by FT-IR spectroscopy was 60 - 61% for all samples in Examples Exp24, 25, 26, 27, 28, and 30.

[0081] The calcification of several different concentrations of PAA with different molecular weights was tested (immersed in SBF for 7 days). The results are summarized in Table 3. Here, (-) means no calcification, (+) means there is some calcification but not complete calcification, and (++) means the surface is completely covered with calcification (shown in Figure 5B).

[0082]

Table 3

[0083] Figures 3A to 5B show the results of remineralization at various time points after immersing demineralized dentin disk samples in SBF. Figure A shows that of the control sample C0, i.e., the sample treated with only water without treatment with the activator solution. Figure B shows that of the sample treated with the above activator solution at 450000 g / mol and 10 mg / l. Figure 3 shows after 1-day immersion, Figure 4 shows after 3-day immersion, and Figure 5 shows after 7-day immersion. The remineralization of the control sample C0 (Figures 3A, 4A, and 5A) was very limited, and only very slight remineralization was observed after 7-day immersion. The samples treated with the above activator solution (Figures 3B, 4B, and 5B) showed significant remineralization already after 3 days.

[0084] Figure 6A shows the same dentin disk as in Figure 5A as a side view. Figure 6B shows the dentin disk of Figure 5B as a side view. As shown, the dentinal tubules in Figure 6B are remineralized on the surface of the disk, while in Figure 6A they basically remain open.

[0085] Figures 7A and 7B (Figure 7B is a partially enlarged view of Figure 7A) show the interface between dentin treated with an activator solution (lower part of the figure, light gray) and a lining material according to the present invention (such as Exp30 after storage in SBF for 2 weeks) applied (upper part of the figure, filler particles are shown in light gray). As shown, a petrified layer or a reactive (ion-rich) layer was formed at the interface between the activated dentin and the backing material. When SEM images of the interface were taken, it was clearly shown that a calcium-rich layer was formed not only in the resin tags inside the demineralized dentin but also at the interface.

[0086] Figure 8 shows a situation where the dentin was not activated with the activating solution of the present invention, but this lining material was used. Comparing with Figures 7A and 7B, it can be seen that the combination of the activator solution and the lining material of the present invention has a significant effect on the calcification of dentin.

[0087] Figures 9, 10, and 11 show the main element compositions of various parts of the interface (shown in Figures 7A and 7B) measured by an energy-dispersive X-ray spectrometer (EDX). Figure 9 shows the composition of the ion-releasing material measured from region 1 (upper part of the figure) of Figure 7B. Figure 10 shows the composition of the calcified layer at the interface measured at point 5 (center of the figure) of Figure 7B. Figure 11 shows the composition of the demineralized dentin measured from region 2 (lower part of the figure) of Figure 7B. As shown, the main element compositions of the ion-rich layer are Ca and P, which promote the remineralization of the activated dentin.

[0088] Figures 12 to 15 show the interfaces between commercially available materials (Comparative Examples C1 to C4) and dentin. Figure 12 uses Fuji II LC (C1) manufactured by GC Dental, Figure 13 uses Fuji IX (C2) manufactured by GC Dental, Figure 14 uses Activa-Liner (C3) manufactured by Pulpdent Corp, USA, and Figure 15 uses Caredyne (C4) manufactured by GC Dental. The results show that no reactive layer or calcified layer was formed at the interfaces between these commercially available materials and dentin.

[0089] Further results of the remineralization tests are shown in Figs. 16 and 17 (different magnifications). These show the dentin surface cut under normal water cooling and immersed in SBF for 1 week. That is, the samples were not treated at all. No remineralization is seen, only a layer of dirt is seen. Figs. 18 and 19 are the same SEM / EDS photographs as Figs. 16 and 17, but for samples cut under this activator solution and stored in SBF for 1 week. It can be seen that remineralization covers the entire surface of the samples. Fig. 20 is a cross-sectional view of the same sample, showing the thickness of the remineralized layer. Fig. 21 shows the main elemental composition of the region marked with a square in Fig. 21, measured by EDX. As is clear here, the activator solution provides an appropriate environment for the remineralization of dentin.

[0090] Fig. 22 shows the test results of the dissolution of calcium (g / kg) in water for 24 hours from the disk samples. The tests were performed on four samples. The first sample on the left was from Example Exp26, the second sample was from Example Exp27, the third sample was the control sample C5, and the fourth sample on the right was from Example Exp30. For each sample, according to this specification, four measurements were made, and each column of each group shows the results. In each group, the leftmost column (the minimum value of each group) shows the measured value by AAS from the total weight of the sample, and the second column from the back shows the measured value by AAS from the weight of the active part of the sample. Naturally, the control sample can only give the AAS from the total weight of the sample. The third column of each group corresponds to the measured value of ISE from the total weight of the sample, and the rightmost column corresponds to the measured value of ISE from the weight of the active part of the sample. The line shows the measured pH of the water in which the sample was immersed. The results show that it is important to include calcium carbonate in the mixture (Examples Exp27 and 30) when rapid calcium release is required.

[0091] Figure 23 shows the results of measuring the dissolution of zinc into water (g / kg) from the sample of Example 30 at three different time points, namely 15 minutes (left), 24 hours (center), and 168 hours (right). The lines indicate the pH of the water in which the sample was immersed. In each column group, the left column shows the measured value by AAS from the total weight of the sample, and the right column shows the measured value by AAS from the weight of the active part of the sample. The results show that the amount of zinc ions released increases with time, thereby causing the pH to change to a more alkaline value.

[0092] Figure 24 shows the measurement results of the dissolution of calcium from the sample of Example 30 into water (g / kg) at three different time points, namely 15 minutes (left), 24 hours (center), and 168 hours (right). The lines indicate the pH of the water in which the sample was immersed. The leftmost column in each column group is the measured value by AAS from the total weight of the sample, and the second column is the measured value by AAS from the weight of the active part of the sample. The third column in each group corresponds to the measured value by ISE from the total weight of the sample, and the rightmost column corresponds to the measured value by ISE from the weight of the active part of the sample. The results show that the amount of calcium ions released increases with time, thereby causing the pH to change to a more alkaline value.

[0093] Figure 25 shows the flexural strength (MPa) of various comparative examples (C6 - C9) having different compositions and components and several samples prepared according to the present specification (Example Exp24, Example Exp25, Example Exp26, Example Exp27, Example Exp28, and Example Exp30). The flexural strength of each sample was measured for the dry sample (left column in each group, the line above the numerical result) and the sample aged by boiling in water at 100 °C for 16 hours (right column in each group, the lower part is the numerical result). The results show that the lining material of the present invention is much stronger than the commercially available comparative materials before and after aging (boiling).

[0094] Figure 26 shows the flexural strength (MPa) of two samples (Examples Exp30 and 31) prepared according to the present specification with different resins. The flexural strength of each sample was measured for the dry sample (left column of both groups) and the sample boiled in water (100 °C) for 16 hours (right column of both groups). The samples were identical in other respects. The samples whose results are shown in the group of the left column used a resin mixture of BisGMA / TEGDMA (50 / 50) (Example Exp30), and the samples whose results are shown in the group of the right column used a resin mixture of UDMA / TEGDMA (70 / 30) (Example Exp31).

[0095] Figure 27 shows the flexural strength (MPa) of comparative samples C10, C11, C8, and C12, and also shows the results of the samples according to Example Exp30. As is clear, the present material significantly improves the flexural strength compared to some commercially available materials and reaches the same flexural strength as some other commercially available materials when compared to some commercially available materials.

[0096] Figure 29 shows the shear bond strength of the dentin surface after various surface treatments of samples S1 to S6 and C13, that is, in MPa units. In each group of samples, the left column shows the results of the samples treated as in Example Exp30 (S1a, S2a, S3a, S4a, S5a, S6a, C13a), and the right column shows the results of the samples treated with a commercially available flowable composite material (S1b, S2b, S3b, S4b, S5b, S6b, C13b). The results show that when only PAA is used for dentin surface treatment, both materials provide the same shear bond strength (Sample S1). When etching is used, the present material significantly improves the shear bond strength (Sample S2). The same effect also applies when MDP is used at 0.4 mg / ml (Sample S3), 2.5 mg / ml (Sample S4), or 5.0 mg / ml (Sample S5) together with PAA. In the case of MDP used at an amount of 8.3 mg / ml (Sample S6) together with PAA or at an amount of 5 mg / ml alone (Sample C13), the material of the present invention provides a shear bond strength slightly lower than that of the commercial product.

[0097] Figure 30, similar to Figure 29, shows the shear bond strength in MPa for various samples (except Sample S5). This figure shows the influence of the PAA concentration and its molecular weight. The lowest result (Sample S9) was obtained with PAA in an amount of 2 g / l, but it is clear that a better shear bond strength is obtained at a concentration of 10 mg / l and a molecular weight of 450,000 g / mol (Sample S5) than those exceeding 4,000,000 g / mol (Sample S7). Similarly, at a molecular weight of 450,000 g / mol, the shear bond strength is higher at a concentration of 10 mg / l (Sample S5) than at 20 mg / l (Sample S8).

[0098] Furthermore, in the case of Sample C14 (using NCC in the activator solution), the shear bond value was 3.9 MPa (SD 2.2). This is the same result as that of Sample C13b, except that only the use of NCC is different in C14. Therefore, the use of NCC did not affect the shear bond strength of the material.

[0099] Figures 31A, 31B, 32A and 32B are SEM photographs of the dentin surface after treatment with 5 mg / ml MDP (i.e., C13; Figures 31A and 31B at different magnifications), or after treatment with 5 mg / ml MDP and PAA (i.e., S5; Figures 32A and 32B at different magnifications). Both samples were immersed in SBF for one week. Clearly, the samples treated with both MDP and PAA show significantly more calcification than when MDP was used alone.

[0100] Figure 33 shows the fracture toughness of the comparative samples C10, C11, C8 and C12, and the samples prepared using the lining material of Example Exp30, in MPa m 1 / 2 as indicated by As. Clearly, the fracture toughness of the materials according to the present specification is significantly higher than that of commercially available materials.

Claims

1. - An aqueous activator solution containing polyacrylic acid having a molecular weight of 250,000 to 600,000 g / mol, wherein the concentration of polyacrylic acid in the solution is 5 to 20 mg / l, and - A lining material, comprising 20 to 80% by weight of a dental resin and 20 to 80% by weight of an ion-releasing material containing at least one of calcium, phosphate, and zinc, based on the total weight of the lining material, The aqueous activator solution further contains 10-methacryloyloxydecyl dihydrogen phosphate at a concentration of 0.8 to 7.5 mg / ml, and a dental restoration kit.

2. The ion-releasing material is selected from hydroxyapatite, carbonated apatite, calcium carbonate, bioactive glass, zinc oxide-containing glass, calcium aluminosilicate glass, titanium oxide-containing glass, and mixtures thereof. The kit according to claim 1.

3. The composition of the ion-releasing material is based on the total weight of the ion-releasing material, - 35 to 55% by weight of carbonated apatite, - 2 to 10% by weight of calcium carbonate, and - 40 to 60% by weight of ZnO-containing glass. The kit according to claim 1 or 2.

4. The dental resin is selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, morpholinoethyl methacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diurethane dimethacrylate, 2,2-bis(4-(2-hydroxy-3-methacryloxy)phenyl)propane, acrylic acid, epoxy, bisphenol A-glycidyl methacrylate, urethane dimethacrylate, trimethylolpropane ethoxylate triacrylate, semi-crystalline polyceram, and mixtures thereof. The kit according to any one of claims 1 to 3.

5. Further comprising an inert filler disposed in the lining material, The relative amounts of the ion-releasing material, the dental resin, and the inert filler are based on the total weight of the lining material, - 30 to 50 wt% of an ion-releasing material, - 30 to 50 wt% of a dental resin, and - 10 to 30 wt% of an inert filler, the kit according to any one of claims 1 to 4.

6. The kit according to claim 5, wherein the inert filler is selected from E glass fiber, S glass fiber, and a mixture thereof.

7. The kit according to any one of claims 1 to 6, further comprising a dental restoration material.

8. The kit according to any one of claims 1 to 7, wherein the activator solution is suitable for use as a drilling solution in tooth restoration or as a surface modifier.

9. The kit according to any one of claims 1 to 8, wherein the lining material is suitable for use as a liner material or a base material in tooth restoration.

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