Dental composition for desensitizing, disinfecting and protecting exposed dentine

TITLE

0002DENTAL COMPOSITION FOR DESENSITIZING, DISINFECTING AND PROTECTING EXPOSED DENTINE

0003DESCRIPTION Field of the invention

0004The present invention relates to dentistry, more precisely it relates to a composition for treating dentinal hypersensitivity and for disinfecting and protecting the teeth and the periodontium. Brief description of the prior art

0005Dentinal hypersensitivity is a symptom that is frequently referred to in odontostomatologic anamnesis. The patient refers a bothersome trouble which occurs by taking hot, cold, sweet and slightly acid food, as well as by toothbrushing .

0006The clinical examination often reveals tooth enamel abrasion or erosion at such dental hypersensitive areas, accompanied by more or less serious dentine exposition; in other cases, a gingival recession causes exposition of the most sensitive part of the tooth, i.e. the transition area between enamel and cementum.

0007Dentine is a tooth part which is radially crossed by many dentinal tubules, which contains dentinal fluid, and are peripherally coated with enamel (in coronal dentine) and by cementum (in radicular dentine) , such that they are substantially impervious. Nerve fibres are also radially arranged between dentine and pulp, which is densely innerved as well. Some of these nerve fibres cross a layer that is called predentine and have an end at the true beginning of the dentinal tubules. Therefore, apart from a few micrometres thick layer, dentine is in large part free from nerve fibres. Nevertheless, tactile, heat or compressive stimulations on the dentine that is exposed due to enamel abrasion or erosion excite the nerve receptors that are located between the pulp and the dentine, causing an electric response and then a pain stimulation. Cases of dentinal hypersensitivity occur when a cavity is made to receive dental filling, in case of changing the cavity-liner, or when creating a dental stump for implanting prosthetic elements; they also occur after scaling and root planning operations and after whitening treatments. Dentinal hypersensitivity is observed, in particular, after that a permanent tooth filling has been completed, as in the case of amalgam or composite tooth fillings. Since the dental filling is stabilised via a retention mechanism, in the case of amalgam filling the use of desensitizing substances is not complicated; on the contrary, in the case of composite dental fillings this procedure cannot be followed, since the dentinal tubules must be pervious to allow adhesion of an adhesive on the dentine. This way, a sealing layer between the composite and the dentine is formed, which, however, is easy to be weakened by exposition to enzymes, such as metalloproteinase .

0008Dentinal hypersensitivity often occurs in the presence of periodontal diseases due to periodontal tissue detachment, which is accompanied by gingival recession and tooth neck exposition. In fact, the exposition of the junction between enamel and cementum, as well as the cementum exposition, softens the exposed cementum and/or the dentine, causing hypersensitivity. As well known, dentinal sensitivity can be considerably reduced by occluding the dentinal tubules orifices, such that their conductance is reduced. Furthermore, substances are known, as potassium nitrate, chloride and oxalate, as well as eugenol, that are adapted to reduce the dentinal sensitivity, via a so-called depolarising effect, i.e. by modifying the sensitivity of the nerve fibres that reach the tubules from the pulp, such that the pulp nerve activity is blocked. In clinical practice, for obstructing dentinal tubules orifices, chemical substances are used in the form of water solutions or gel, as well as physical treatments for mechanically obstructing dentinal tubules openings are known. Among the chemical means, there are ferric and potassium oxalate, which reacts with the calcium ions of the saliva forming calcium oxalate, which precipitates. Silver nitrate and tin fluoride can also be used, to form silver and tin complex precipitates, respectively, as well as strontium salts and other metal salts. Moreover, insoluble salts, such as calcium phosphate, hydroxyapatite, colloidal silica, etc., can be used, which occlude directly the tubular orifices. For this purpose, glass ionomer cement and resins of various kinds can also be used. Among the physical means, the most popular are laser or the use of a pulsed ultrasonic sealer, which cause the production of a consistent amount of smear layer debris that subsequently occlude the tubules.

0009In the present practice, dentine desensitizing is carried out by means of chemical tubules occlusion techniques, or by means of physical techniques that prevent the dentinal fluids from moving inside the dentinal tubules, or by means of depolarizing substances.

0010However, although the well-known techniques for obstructing dentinal tubules are rather simple to use, they have not become very popular among the dentists. Similarly, depolarising substances have a short-lasting efficacy, due to the difficulty of keeping a sufficiently high potassium ions concentration within the dentinal tubules. Methods based on glass-ionomer cement and photo- activated resins provide a more long-lasting desensitizing effect, but they are suitable for treating only very deep erosion cases, and are difficult to use. Finally, laser treatment or pulsed ultrasonic sealer treatment exhibits about the same effectiveness as soluble salt, in terms of percentage of success and effect duration, but require a quite expensive equipment .

0011Even if the currently used desensitizing substances have a rather satisfactory effectiveness, the need is felt of a product which has improved desensitizing features, as well as a disinfecting efficacy, and which provides a protection against metalloproteinase.

0012Summary of the invention

0013It is therefore a feature of the present invention to provide a dental composition for desensitizing, disinfecting and protecting exposed dentine, which does not exhibit the drawbacks of the well-known treatments.

0014It is another feature of the invention to provide such a composition which can be topically applied on a sensitive zone in a simple way, for example by means of a small brush or a microsponge.

0015It is also a feature of the present invention to provide such a composition, which can be used in desensitizing, disinfecting and protecting dentine therapy.

0016It is a further feature of the invention to provide such a composition, which exhibits an improved efficacy in creating a quite deep occlusion inside the dentinal tubules, but leaving pervious the last 3-6 microns of tubule length.

0017It is still another feature of the invention to provide such a composition, which is suitable for depolarizing dentinal nerve fibres. It is also a feature of the invention to provide such a composition, which offers protection against metalloproteinase of the collagen that is present in the hybrid layer of the dentine that has been pre-treated with ortho-phosphoric acid.

0018It is finally a feature of the invention to provide such a composition, which has a high desensitizing/ protective response and therefore a long lasting adhesive stability. These and other features are reached with an exemplary composition, according to the invention, for desensitizing, disinfecting and protecting exposed dentine, the composition comprising:

0019- a substance that causes a precipitation within the dentinal tubules of a calcium-containing substance;

0020- a substance that stabilizes the precipitated calcium-containing substance; the main feature of which is that the substance that stabilizes is an acrylic polymer. Advantageously, the substance that causes a precipitation within the dentinal tubules of a calcium- containing substance is selected from the group comprised of:

0021- oxalic acid; - potassium oxalate;

0022- a fluorine salt;

0023- or a combination thereof .

0024In particular, the precipitated calcium-containing substance can be selected from the group comprised of: calcium oxalate, calcium fluoride, or a combination thereof .

0025Advantageously, the composition comprises, furthermore, a disinfecting substance. Preferably, the disinfecting substance is a cationic disinfecting substance .

0026In particular, the cationic disinfecting substance is selected from the group comprised of : benzalkonium chloride, benzethonium chloride, chlorhexidine , cetrimide, cetylpyridinium chloride, chlorhexidine gluconate.

0027Advantageously, the soluble fluorine salt is selected from the group comprised of: potassium fluoride, sodium fluoride, sodium monofluorophosphate , potassium monofluorophosphate, amine fluoride, or a combination thereof .

0028Preferably, the acrylic polymer is HEMA (2- hydroxyethylmetacrylate) .

0029The pharmaceutical composition, according to the invention, allows to overcome the above-described drawbacks, due to the moderate effectiveness of the commonly used desensitizing substances.

0030The association of a cationic disinfecting substance with an acrylic polymer, with the chlorhexidine, with oxalic acid and/or with a fluorine salt allows to obtain, surprisingly, a high desensitizing and protecting efficacy towards dentine. This surprising activity depends upon a synergistic action of the cationic disinfecting substances, oxalic acid, fluoride ion, and the acrylic polymer .

0031It is well known from literature, in fact,^that a desensitizing activity of the disinfecting substances arises, when they are applied on exposed dentine, since the disinfecting substances reduce the bacterial plaque and reduce also all the reaction and degradation products of the bacteria that can otherwise penetrate the dentinal tubules, which are pervious due to dentine exposition. In particular, chlorhexidine, furthermore, might inhibit metalloproteinase, while oxalic acid and fluorine salts might create a deep obstruction inside the tubules. The HEMA might stabilize the calcium oxalate and calcium fluoride crystals, which are formed deep within the dentinal tubules . The potassium ions might act on the nerve fibres that are contained in the dentinal tubules, thus lowering the sensitivity threshold.

0032For example, the solution may have the following weight proportions : HEMA 5-40%,

0033Chlorhexidine gluconate 0.1-5%,

0034Oxalic acid 0,5-5%,

0035Potassium fluoride 0,1-5%,

0036Ethyl alcohol 96° 1-40%, Depurated water up to 100 ml.

0037The use of a cationic disinfecting substance together with an acrylic polymer, oxalic acid and/or a soluble fluorine salt, is unknown in dentistry practice, where, instead, a combination of these substances can be profitably used according to the present invention.

0038Some examples of dental compositions, according to the present invention, are presented below, for desensitizing, disinfecting and protecting the exposed dentine .

0039EXAMPLE 1 A desensitizing, disinfecting and protecting composition that provides the use of a solution based on chlorhexidine gluconate and oxalic acid together with HEMA and Potassium fluoride; the composition is packaged in 0,5 ml PE single-dose ampoules or in 5 ml glass small vials, equipped with dropper, and has the following weight proportions:

0040Oxalic acid 3%, Chlorhexidine gluconate 2%, 2-hydroxyethylmetacrylate (HEMA) 35%, Potassium fluoride 2%, Depurated water up to 100%.

0041EXAMPLE 2 A desensitizing, disinfecting and protecting composition that provides the use of a solution based on chlorhexidine gluconate and oxalic acid together with HEMA; the composition is packaged in 0,5 ml PE single-dose ampoules or in 5 ml glass small vials, equipped with dropper, and has the following weight proportions:

0042Oxalic acid 3%,

0043Chlorhexidine gluconate 2%,

00442-hydroxyethylmetacrylate (HEMA) 35%,

0045Depurated water up to 100%. EXAMPLE 3

0046A desensitizing, disinfecting and protecting composition that provides the use of a solution based on chlorhexidine gluconate and oxalic acid together with HEMA; the composition is packaged in 0,5 ml PE single-dose ampoules or in 5 ml glass small vials, equipped with dropper, and has the following weight proportions: Oxalic acid 3%, Chlorhexidine gluconate 2%, 2-hydroxyethylmetacrylate (HEMA) 35%, Ethyl alcohol 30%,

0047Depurated water up to 100%.

EXAMPLE 4

0049A desensitizing, disinfecting and protecting composition that provides the use of a solution based on chlorhexidine gluconate and potassium fluoride together with HEMA; the composition is packaged in 0,5 ml PE single-dose ampoules or in 5 ml glass small vials, equipped with dropper, and has the following weight proportions :

0050Potassium fluoride 3%, Chlorhexidine gluconate 2%, 2-hydroxyethylmetacrylate (HEMA) 35%, Depurated water up to 100%.

EXAMPLE 5

0052A desensitizing, disinfecting and protecting composition that provides the use of a solution based on chlorhexidine gluconate and potassium oxalate together with HEMA; the composition is packaged in 0,5 ml PE single-dose ampoules or in 5 ml glass small vials, equipped with dropper, and has the following weight proportions : Potassium oxalate 3%,

0053Chlorhexidine gluconate 2%,

00542-hydroxyethylmetacrylate (HEMA) 35%,

0055Depurated water up to 100%.g

0056Such compositions are used in a desensitizing, disinfecting and protective treatment, as described below:

0057Cleaning the dentine surface to remove bacterial plaque; treating recesses after cleaning and applying 37% orthophosphoric acid mordant gel, abundantly washing with water. Carefully drying with an air jet for about 10 seconds, if a severe hypersensitivity is present, or just drying with a cotton swab;

0058Applying the liquid: squeezing the single-dose content directly on the area to be treated or in a mixing vessel of a disposable kit (if the product is packaged in small vials equipped with a dropper) . Then picking up the liquid solution with a small brush or microsponge and delicately rubbing for about 10 seconds. The composition is particularly indicated for treating a composite dental filling preparation, but, more in general, it can be used to treat any dental regions which exhibit enamel erosion or wear, or in patients who are affected by a gingival recession, in which the junction between enamel and cementum is exposed. The composition can also be applied on dental prosthetic stumps, after scaling and root planning, or after a whitening treatment.

0059The foregoing description of specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiments without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.