Prevention and treatment of periodontal and peri-implant disease

Abstract

This document relates to the field of dentistry and to the treatment and prevention of oral inflammation and / or oral infection and / or use in endodontic procedures by using chitosan gel, optionally in combination with a brush having bristles comprising chitosan.

Description

[Technical field]

[0001] The present invention relates to the field of dentistry and in particular to the treatment and prevention of periodontal and peri-implant diseases, in particular gingivitis, mucositis, periodontitis and peri-implantitis, as well as endodontic procedures. [Background technology]

[0002] Medical implants are frequently implanted today in vertebrates, including humans, to replace anatomical structures and / or to restore bodily function or appearance.

[0003] Medical implants can be made of various materials depending on their application. Examples of materials include composite materials (mixed materials with no chemical bonds between them) and biodegradable materials that are absorbed by the body once they have completed their task. Biodegradable materials are not only absorbed by the body, but rather metabolized within the body, and the end products are secreted, excreted, or expelled entirely from the body, for example in the form of water and carbon dioxide. Silicone implants can be used to replace soft tissue sections. Stainless steel is a strong material that is often used when high mechanical strength is required, such as to repair a fracture or to replace part of a joint. Polyethylene implants can be used as part of a joint replacement implant.

[0004] Also, many medical implants, such as dental implants, orthopedic implants, and vascular stents, are metallic, i.e., made of metallic materials. Examples of metallic materials commonly used to construct metallic medical implants include steel, titanium, zirconium, tantalum, niobium, hafnium, and alloys thereof. In particular, titanium and titanium alloys have proven to be suitable for use in the construction of medical implants. This is due to the fact that titanium is biocompatible, has excellent corrosion resistance in body fluids, and is lightweight and sturdy.

[0005] Dental implants are used in dental restorative procedures in patients who are missing one or more teeth. Dental implants include a dental fixture that is used as an artificial root replacement. The dental fixture thus functions as the root of a new tooth. The dental fixture is typically screw-shaped, i.e., the dental fixture has a screw thread. The implant is surgically implanted into the jawbone, after which bone tissue grows around the fixture, optimally with the bone in direct contact with the implant surface. The process of integrating the implant into the bone is called osseointegration, when the bone grows in direct contact with the surface of the embedded fixture. Osseointegration results in a firm and permanent placement of the implant.

[0006] In patients with implants, the periodontitis-like condition may progress to a condition called peri-implantitis, which is caused by bacterial colonization on the surface of the implant. This condition is a new disease entity that has emerged with the more widespread use of dental implants. So far, no predictable treatment strategies have been developed to cure peri-implantitis, and no evidence-based treatment regimes are currently available. Infection may be caused by bacteria, for example, in the case of poor oral hygiene. Inflammation in the tissues around the implant may cause bone loss if left untreated, which may ultimately lead to the loss of the implant. Patients with implants are also prone to developing a condition called peri-implant mucositis. This condition involves the presence of inflammation in the mucosa around the implant, but there is no sign of loss of supporting bone, in contrast to the bone loss observed in patients with peri-implantitis.

[0007] Treatment of periodontal disease usually involves removing bacterial deposits and calculus. This is usually done by manually scraping the exposed root surface and removing bacterial deposits and calculus, including subgingival deposits. However, it is difficult to achieve complete access to treat the deeper periodontal pockets, resulting in residual bacteria that may reinfect the tissue. Therefore, treatment is often combined with a surgical procedure to open the tooth pocket and expose the tooth. The root is then mechanically freed from bacterial deposits and calculus, as well as removing granulation tissue and bacterial toxins. Alternative treatments include debridement and rinsing of the underlying affected tissue, and local or systemic treatment with antibiotics and anti-inflammatory drugs.

[0008] Bacterial infections around the implant are treated similarly with debridement of the exposed surface.

[0009] Additionally, in many cases it may be advantageous or necessary to debride the surgically exposed hard tissue surface, for example, debridement of the surgically exposed hard tissue surface may be advantageous or necessary prior to the regenerative procedure, i.e., to prepare the hard tissue surface for the regenerative procedure.

[0010] A rapid wound debridement procedure is important to ensure a better overall treatment outcome. In addition, the overall treatment outcome may also depend on the degree of damage caused to the anatomical structures by the debridement instruments used during the wound debridement procedure. Furthermore, the overall treatment outcome may also depend on the amount of contaminant residue left by the debridement instruments on the treated surface. The contaminant residue may cause a foreign body reaction, a toxic reaction, or inflammation disproportionate to its beneficial effect.

[0011] In addition, after the implant is placed in the body, the surface of the implant and the surrounding tissues may need to be cleaned. This is particularly important if infection or contamination occurs. In these cases, it is necessary to remove microorganisms and contaminants from the surface of the failed implant to prevent disease progression and allow the implant to reintegrate. To maintain a stable treatment outcome and prevent further disease progression, the implant surface also needs to be cleaned regularly, both by the patient and by dental care workers in the clinic. If the implant surface is not adequately cleaned and maintained, disease may progress and ultimately result in the loss of both the implant and the surrounding tissues, such as the jawbone.

[0012] The instruments commonly used today to clean metallic implants are mostly designed for tooth cleaning and are relatively hard and sharp to provide thorough cleaning of the root surface. Such cleaning instruments can be made of, for example, stainless steel, titanium, hard alloys, or hard polymers. These instruments may not always be suitable for cleaning medical and / or dental implants, which often have delicate surface structures that can be damaged when debridement is performed with hard and sharp cleaning instruments. In addition, such cleaning instruments may destroy the implant surface morphology and may form surface lesions in which bacteria may hide and adhere, making surface decontamination difficult.

[0013] Additionally, cleaning instruments currently used for implant debridement leave contaminant residues on the medical implant surface or peri-implant tissues that can cause toxic or foreign body and / or other inflammatory responses out of proportion to their beneficial effects, which may further expand peri-implant disease and therefore cause further loss of implant fixtures.

[0014] Periodontal disease is caused by bacteria in plaque, a film that constantly forms on the surfaces of teeth. The disease is very common; it is estimated that between 70-90% of the world's population is affected. Periodontal disease is the leading cause of tooth loss in people over the age of 35. The most common forms of periodontal disease are gingivitis and periodontitis.

[0015] If endodontic infections are left untreated, bacteria can spread from the root canal into the surrounding bone and soft tissue. The spread of bacteria can cause acute infections, which, if left untreated, can lead to high patient morbidity. There is also a need to develop antimicrobial agents to improve the outcome of root canal treatment.

[0016] WO2013072308 discloses a dental cleaning instrument in which the bristles comprise chitosan.

[0017] Mayer et al. (Clin Exp Dent Res. 2020;1-8.) describe the use of chitosan brushes for cleaning teeth.

[0018] However, there is a need for improved treatment and prevention of periodontal disease and conditions related to dental implants. There is also a need for better antibacterial agents for endodontic procedures. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] WO2013072308 [Non-patent literature]

[0020] [Non-Patent Document 1] Mayer et al. (Clin Exp Dent Res. 2020;1-8.) Summary of the Invention [Means for solving the problem]

[0021] This document discloses hydrogels comprising chitosan (also referred to herein as chitosan hydrogels, etc.) for use in the treatment and / or prevention of oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures.

[0022] The oral inflammatory condition and / or oral infection may be periodontal disease, peri-implant disease, oral wounds and / or aphthous lesions. Non-limiting examples of periodontal disease include gingivitis, oral mucositis and / or periodontitis, including both marginal and apical periodontitis. Non-limiting examples of peri-implant disease include peri-implant mucositis and / or peri-implantitis. The oral infection may be bacterial, viral and / or fungal infection.

[0023] Chitosan hydrogels typically have a pH of about 2.5 to about 7.0, e.g., about 2.5 to about 6, about 3 to about 6, about 2.5 to about 5.2, about 2.5 to about 5.0, about 2.5 to about 4.5, about 2.5 to about 4, about 2.5 to about 3.8, about 3 to about 4.5, about 3 to about 4, about 3.2 to about 3.8, or about 2.5 to about 3.5.

[0024] Chitosan hydrogels typically have a viscosity of about 50 to about 3000 mPaS, for example, about 500 to about 3000 or about 50 to about 2000 mPaS, for example, about 100 to about 2000 mPaS.

[0025] The concentration of chitosan in the chitosan hydrogel is typically about 2 wt% to about 10 wt%, for example, about 3 wt% to about 9 wt%, for example, about 2 wt% to about 6 wt%, for example, about 2 wt% to about 5 wt%, for example, about 3 wt% to about 6 wt%, for example, about 3 wt% to about 5 wt%, for example, about 3.5 wt% to about 4.5 wt%, for example, about 4 wt%.

[0026] The molecular weight of chitosan is typically from 50 to 1000 kDa, for example from 50 to 600 or from 50 to 400 kDa.

[0027] The degree of deacetylation of the chitosan hydrogel is typically between 68% and 99.9%, typically between 85% and 99%, for example at least 80% or at least 90% or 98%.

[0028] The chitosan hydrogel may include an acid selected from one or more of the acids selected from the group consisting of acetic acid, hyaluronic acid, formic acid, oleanolic acid, and lactic acid.

[0029] The concentration of formic acid may be 0.5 wt % to 10 wt %, for example, 0.5 wt % to 4 wt %.

[0030] The concentration of hyaluronic acid may be 0.5 wt% to 10 wt%, for example, 0.5 wt% to 4 wt%.

[0031] The concentration of oleanolic acid may be 0.5 wt % to 10 wt %, for example 0.5 wt % to 4 wt %.

[0032] The concentration of lactic acid may be 0.5 wt % to 10 wt %, for example, 0.5 wt % to 4 wt %.

[0033] The concentration of acetic acid may be 1 wt % to 10 wt %, for example, 2 wt % to 10 wt %.

[0034] Chitosan hydrogels may, for example, consist of water and / or alcohol such as ethanol as a solvent, chitosan, chlorhexidine, hydrogen peroxide, iodine, and pH adjusters, such as one or more of the acids selected from the group consisting of acetic acid, hyaluronic acid, formic acid, oleanolic acid, and lactic acid. Chitosan hydrogels may, for example, alternatively consist of water and / or alcohol such as ethanol as a solvent, chitosan, hydrogen peroxide, iodine, and pH adjusters, such as one or more of the acids selected from the group consisting of acetic acid, formic acid, oleanolic acid, and lactic acid, and optionally additives, such as hyaluronic acid and oleanolic acid. Alternatively, the hydrogels may consist of chitosan, an aqueous solvent, such as water and / or alcohol (such as ethanol), and one or more pH adjusters, such as lactic acid, acetic acid, formic acid, and / or oleanolic acid.

[0035] This document also relates to chitosan hydrogels as so defined herein.

[0036] The chitosan hydrogel can be used with a brush containing bristles that include or consist of chitosan. The brush may include an insert for a rotary, vibrating, or ultrasonic handpiece.

[0037] This document also discloses a method for treating and / or preventing oral inflammatory conditions and / or oral infections and / or for use in endodontic treatment, comprising applying a chitosan hydrogel as defined herein to an oral surface, such as the interior or exterior of a tooth, a dental root, or a dental implant surface, of a patient in need thereof, which may further comprise treating the oral surface to which the hydrogel has been applied with a brush as defined herein.

[0038] This document also discloses a chitosan hydrogel as defined herein for the manufacture of a medicament for the treatment and / or prevention of oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures.

[0039] This document a) a brush with bristles containing chitosan; b) chitosan hydrogel as defined herein; Also disclosed are kits that optionally include c) a device, such as a syringe, for applying the hydrogel to an oral surface, such as a tooth surface or a dental implant surface. [Brief description of the drawings]

[0040] [Figure 1] FIG. 1 shows the solubility of test group 1 (pH 3.48) visually inspected at 15 minute intervals. [Diagram 2] FIG. 1 shows the solubility of test group 1 (pH 4.0) visually inspected at 15 minute intervals. [Diagram 3] FIG. 3 is an expanded view of the results from FIGS. 1 and 2 at selected time points. [Figure 4] FIG. 1 shows fiber solubility by visual inspection after 18 hours: test group 1 (top left), test group 2 (middle left), negative controls: water at pH 7 (top right), human saliva at pH 6.8 (middle right) and EDTA (bottom, from left to right: a) baseline, b) 105 min, c) 150 min). [Diagram 5] FIG. 1 shows the results of Group 1 of Example 5: positive control, untreated implants. [Figure 6] FIG. 1 shows the results for Group 2 of Example 5: Chitosan brush alone. [Figure 7] Figure 13 shows the results of Group 3 of Example 5: Chitosan brush with 4% chitosan gel at pH 3.86. [Figure 8] Figure 13 shows the results of Example 5, Group 4: Chitosan brush with 90% lactic acid, pH 3.86. [Figure 9] Figure 5 shows the results of Group 5 of Example 5: Chitosan brush with 4% chitosan gel at pH 3.86 + sterile saline rinse. The arrow indicates an artifact, i.e. gel dripped onto the agar plate before rinsing the coin with saline. [Figure 10]Figure 13 shows the results of Group 6 of Example 5: Chitosan brush with 4% chitosan alone at pH 5.83. [Figure 11] FIG. 1 shows the results of Group 7 of Example 5: Chitosan brush with 4% sterile (autoclaved) chitosan gel at pH 3.86. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Unless otherwise specified, all percentages herein are weight / weight.

[0042] This document relates to hydrogels comprising chitosan (also referred to herein as chitosan hydrogels), either alone or in combination with instruments comprising bristles comprising a bioabsorbable polymer such as chitosan, for use in the treatment and / or prevention of oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures. This document also relates to the chitosan hydrogel itself, as well as kits comprising the chitosan hydrogel and a debridement and / or cleaning instrument having bristles comprising chitosan.

[0043] Chitosan Hydrogel The hydrogel according to this document comprises chitosan, a linear polysaccharide composed of randomly distributed β-(1→4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). Chitosan is usually derived from shrimp shells.

[0044] The chitosan hydrogels disclosed herein have several advantages when used for the treatment and / or prevention of periodontal disease and / or for endodontic treatment. Chitosan hydrogel itself has antibacterial and anti-inflammatory effects. When applied to a surface, such as a tooth or implant surface, the chitosan hydrogel can prevent the growth of microorganisms, such as bacteria, allowing time for the epithelium to grow and come into contact with the dental surface (such as a tooth or root) or implant. In contrast to antibiotics, there is no risk of developing resistance to chitosan hydrogel. Furthermore, in addition to the antibacterial effect, chitosan hydrogel can have an anti-inflammatory effect on the treated surface and / or nearby surfaces.

[0045] The chitosan hydrogels herein typically have a pH of about 2.5 to about 7.0, e.g., about 2.5 to about 6, about 3 to about 6, about 2.5 to about 6, about 2.5 to about 5.2, about 2.5 to about 5.0, about 2.5 to about 4.5, about 2.5 to about 4, about 2.5 to about 3.8, about 3 to about 4.5, about 3 to about 4, about 3.2 to about 3.8, or about 2.5 to about 3.5.

[0046] The acidic pH of chitosan hydrogel, when applied to oral surfaces such as root or implant surfaces, results in the removal of biofilm, damaged epithelium, and / or stimulates the growth of connective tissue. The combination of chitosan and low pH provides better cleaning, antibacterial, and / or anti-inflammatory effects than chitosan or acid alone. The pH selection of chitosan hydrogel allows for good antibacterial activity without the pH being so low that application to the body becomes painful.

[0047] The pH of the chitosan hydrogel is typically adjusted by the presence of a pH adjuster such as an acid. Examples of acids suitable for adjusting the pH are acetic acid, hyaluronic acid, formic acid, oleanolic acid, and lactic acid. Typically, formic acid and / or oleanolic acid are combined with acetic acid, hyaluronic acid, and / or lactic acid. The acetic acid, hyaluronic acid, and / or lactic acid ensure proper dissolution of the chitosan. Formic acid and / or oleanolic acid are advantageous for use in chitosan hydrogels because these acids exert excellent antibacterial effects while not being too strong and therefore can be safely applied to body surfaces. The concentration of formic acid, oleanolic acid, lactic acid, and hyaluronic acid in the chitosan hydrogel is typically 0.5 wt% to 10 wt%, for example 0.5 wt% to 4 wt%. The concentration of acetic acid is typically 2 wt% to 10 wt% when used alone, and 1 wt% to 10 wt% when used in combination with formic acid, oleanolic acid, lactic acid and / or hyaluronic acid.

[0048] Chitosan hydrogel has a viscosity that allows it to remain on the surface to which it is applied. Typically, the viscosity is about 50 to about 3000 mPaS, for example, about 500 to about 3000 or about 50 to about 2000 mPaS, for example, about 100 to about 2000 mPaS, i.e., 0.05 to 3 Ns / m 2 , 0.5~3Ns / m 2 , 0.05~2Ns / m 2 , or 0.1 to 2 Ns / m 2 This allows the chitosan hydrogel to bind to the treated surface, such as a tooth surface or an implant surface, and slowly degrade, thus exerting its effect for a long period of time. If the viscosity of the chitosan hydrogel is too high, it will be very viscous, making the gel difficult to apply and unable to disperse properly on the applied surface. However, the chitosan hydrogel disclosed herein can efficiently deliver the chitosan gel to the surface by providing a low pH with a large amount of chitosan. Furthermore, the specified viscosity allows the chitosan hydrogel to remain on the applied surface for several days, even weeks.

[0049] The concentration of chitosan in the chitosan hydrogel is typically about 2 wt% to about 10 wt%, for example, about 3 wt% to about 9 wt%, for example, about 2 wt% to about 6 wt%, for example, about 2 wt% to about 5 wt%, for example, about 3 wt% to about 6 wt%, for example, about 3 wt% to about 5 wt%, for example, about 3.5 wt% to about 4.5 wt%, for example, about 4 wt%. The molecular weight of chitosan is typically about 50 to about 1000 kDa, for example, about 50 to about 600 or about 50 to about 400 kDa. The lower the molecular weight, the better the antibacterial effect. However, the molecular weight cannot be too low, since it becomes impossible to form a hydrogel with a sufficiently high viscosity.

[0050] The viscosity of chitosan hydrogels depends on both the chitosan concentration and the molecular weight of chitosan: the higher the chitosan concentration and / or the higher the molecular weight of chitosan, the higher the viscosity.

[0051] Chitosan hydrogels are typically aqueous and contain a solvent selected from water and / or an alcohol such as ethanol. The addition of an alcohol such as ethanol can increase the chitosan concentration on the surface to which the chitosan hydrogel is applied without the need to increase the concentration of chitosan in the hydrogel (which can make the chitosan hydrogel difficult to apply). This is because after the chitosan hydrogel is applied to the surface, the alcohol evaporates quickly, thereby making the chitosan hydrogel more concentrated in chitosan and more viscous. This allows the chitosan hydrogel to remain more easily on the surface to which it is applied. As disclosed below, the concentration of chitosan on the surface to which the chitosan hydrogel is applied can also be increased by treating the surface with a brush having bristles containing chitosan. The use of alcohol can increase the concentration of chitosan in, for example, a 4 wt% chitosan hydrogel to 8 wt% on the surface to which it is applied. When a surface is treated with a brush having bristles containing chitosan, the concentration of chitosan on the treated surface can optionally be increased to up to 15 wt %.

[0052] The chitosan hydrogel may be free of additional antimicrobial agents such as antibiotics and / or chlorhexidine. The chitosan hydrogel may be free of crosslinkers.

[0053] The chitosan hydrogel of this document may be composed of chitosan, chlorhexidine, hydrogen peroxide, iodine, an aqueous solvent, such as water and / or alcohol (such as ethanol), and one or more pH adjusters, such as one or more of the acids selected from the group consisting of acetic acid, hyaluronic acid, formic acid, oleanolic acid, and lactic acid. The chitosan hydrogel may alternatively be composed of water and / or alcohol, such as ethanol, chitosan, hydrogen peroxide, iodine, and one or more of the pH adjusters, such as one or more of the acids selected from the group consisting of acetic acid, formic acid, oleanolic acid, and lactic acid, and optionally additives, such as hyaluronic acid and oleanolic acid. One example of a chitosan hydrogel comprises or consists of water, chitosan, chlorhexidine, hydrogen peroxide, iodine, acetic acid, and formic acid and / or oleanolic acid. Another example of the chitosan hydrogel of this document comprises or consists of water, chitosan, hydrogen peroxide, iodine, acetic acid, and formic acid and / or oleanolic acid. Another example of the chitosan hydrogel comprises or consists of water, ethanol, chitosan, chlorhexidine, hydrogen peroxide, iodine, acetic acid, and formic acid and / or oleanolic acid. Another example of the chitosan hydrogel comprises or consists of water, ethanol, chitosan, hydrogen peroxide, iodine, acetic acid, and formic acid and / or oleanolic acid. Yet another example of the chitosan hydrogel comprises or consists of ethanol, chitosan, chlorhexidine, hydrogen peroxide, iodine, acetic acid, and formic acid and / or oleanolic acid. Another example of the chitosan hydrogel comprises or consists of ethanol, chitosan, hydrogen peroxide, iodine, acetic acid, and formic acid and / or oleanolic acid. For example, the chitosan hydrogel may be comprised of chitosan, an aqueous solvent, such as water and / or alcohol (such as ethanol), and one or more pH adjusting agents, such as lactic acid, acetic acid, formic acid, and / or oleanolic acid. Another example of a chitosan hydrogel herein is comprised of an aqueous solvent, such as water and / or alcohol (such as ethanol), chitosan at a concentration of about 4%, and lactic acid, and the pH of the chitosan hydrogel is about 3.5 to about 4, for example about 3.8.

[0054] Another example of a chitosan hydrogel comprises or consists of an aqueous solvent, such as water and / or alcohol (eg, ethanol), chitosan, chlorhexidine digluconate, dexanthenol, and allantoin.

[0055] The chitosan hydrogel may also contain stabilizers such as glycerin, urea, ascorbic acid, potassium sorbate or polysorbate 20, tocopherol and / or collagen.

[0056] The degree of deacetylation of the chitosan used in the chitosan hydrogel is typically between 68% and 99.9%, and typically between 85% and 99%. The degree of deacetylation may be, for example, at least 80%, more preferably at least 90% or 98%, thereby providing a suitable antimicrobial effect. Furthermore, this degree of deacetylation results in a suitable degradation rate and / or a better bacteriostatic effect of the chitosan gel when applied to the surface to be treated.

[0057] Preparation of chitosan hydrogels The chitosan hydrogels disclosed herein are typically prepared by dissolving an appropriate amount of chitosan in an acidic aqueous solvent such as water (such as sterile water) and / or alcohol, with the pH adjusted with a pH adjuster.

[0058] The solution is typically stirred for a period of time, such as about 1-3 hours, for example about 2 hours. At the same time, the solution may be slowly heated to a temperature of about 50°C.

[0059] Potential impurities in the mixed solution are then removed by filtering through a sterile filter, such as a 125 μm PE filter, for example using a Buchner funnel and a vacuum chamber.

[0060] The solution can then be first sonicated for about 20 minutes and then cooled to about 20°C.

[0061] Sterility is achieved, for example, by steam sterilizing the solution in the primary packaging, capped glass vials, for example using a steam sterilization cycle (Ph.Eur.5.1.1 reference cycle) with a process holding temperature of ≥ 121°C for ≥ 15 minutes.

[0062] Use of chitosan hydrogels with brushes having bristles containing chitosan - Patent Application 20070123633 This document a) a brush as defined herein comprising bristles comprising or consisting of chitosan; b) chitosan hydrogel as defined herein; c) optionally a device, such as a syringe, for applying the hydrogel to oral surfaces; The present invention also relates to a kit comprising:

[0063] The brush includes bristles that include or consist of chitosan.

[0064] The length of the bristles may be 0.5 to 50 mm. Apart from bristles, other structures for cleaning are also feasible, such as filaments or other flexible elements made of bioabsorbable polymers. Such elements are encompassed herein by terms such as "bristles".

[0065] The brush may comprise a cleaning portion and a gripping portion, which may have a means for attaching the brush to a motor-driven device such as a rotary, vibrating, or ultrasonic handpiece.

[0066] The brushes are typically twist-in-wire brushes in which bristles including or made of a bioabsorbable polymer are twisted between the wires. The brushes may also include an insert for a rotary, vibrating, or ultrasonic handpiece.

[0067] An example of a brush suitable for use according to the present document is disclosed in WO2013072308. A specific example of a brush is the Labrida BioClean® brush (Labrida AS, Slemdalsveien1, 0369 Oslo, Norway). The Labrida BioClean® brush is a twist-in-wire brush with chitosan bristles twisted between steel wires and includes an insert for a rotary, vibrating, or ultrasonic handpiece.

[0068] Brushes are sometimes referred to as debridement, tooth, and / or implant cleaning instruments.

[0069] The degree of deacetylation of the chitosan used in the chitosan bristles of the brush is typically at least 50%.

[0070] The combined use of the chitosan hydrogel defined herein and the brush defined herein improves cleaning and / or debridement of the treated surface. For example, microorganisms, biofilms, and / or infected, inflamed, and / or dead tissue are efficiently removed from the treated surface. Further advantages are disclosed elsewhere herein.

[0071] Furthermore, when the chitosan hydrogel disclosed herein is used with a brush as defined herein, especially when the bristles comprise or consist of chitosan, the chitosan gel dissolves the bristles that may become loose during use of the tool, leading to a more rapid removal of the loose bristles from the body and / or contributing to an increased concentration of chitosan around the treated surface, as described elsewhere herein. When using other cleaning tools that do not contain bioabsorbable polymers, there is a risk that the loose bristles will remain in the body, which may, for example, hinder healing and cause undesirable reactions such as inflammation and / or allergies. As mentioned above, the chitosan hydrogel of this document in combination with a brush having bristles that comprise or consist of chitosan provides an efficient treatment of the surface while avoiding loose bristles remaining in the body due to the dissolving effect of the chitosan hydrogel on the chitosan bristles. Also, as disclosed elsewhere herein, the use of chitosan hydrogel in combination with a brush with bristles containing or consisting of chitosan allows the bristles to dissolve during use, thus allowing for a larger amount of chitosan to be delivered to the treatment site without the need to increase the chitosan concentration in the hydrogel beyond what can be practically handled.In contrast, a chitosan hydrogel with too much chitosan will be too viscous to be applied to a surface in a convenient manner.For example, a hydrogel with too high a viscosity cannot be applied using a syringe.

[0072] Therefore, this document also relates to the medical uses of the chitosan hydrogels disclosed herein, together with brushes with chitosan bristles disclosed herein for the medical uses disclosed herein.

[0073] Medical Applications of Chitosan Hydrogel This document also relates to chitosan hydrogels as defined herein for use in the treatment and / or prevention of oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures. Optionally, the chitosan hydrogels may be used in combination with brushes equipped with chitosan bristles for such medical applications.

[0074] This document also relates to the use of a chitosan hydrogel as defined herein for the manufacture of a medicament for the treatment and / or prevention of oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures. Optionally, the chitosan hydrogel may be used for such medical applications in combination with a brush equipped with chitosan bristles, as described elsewhere herein.

[0075] This document also relates to methods for treating and / or preventing oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures, comprising applying a hydrogel as defined herein to an oral surface of a patient in need thereof, such as a tooth, a tooth root, or a dental implant. Optionally, chitosan hydrogel may be used in such methods in combination with a brush equipped with chitosan bristles, as described elsewhere herein.

[0076] The oral inflammatory condition and / or oral infection may be periodontal disease, peri-implant disease, oral wounds and / or aphthous lesions. Non-limiting examples of periodontal disease include gingivitis, oral mucositis and / or periodontitis, either marginal or apical periodontitis. Non-limiting examples of peri-implant disease include peri-implant mucositis and / or peri-implantitis. The oral infection may be bacterial, viral and / or fungal infection.

[0077] When chitosan hydrogel is used for the treatment and / or prevention of oral inflammatory conditions and / or oral infections and / or for endodontic treatment, the chitosan gel is applied to the surface to be treated, such as a dental surface, e.g., the interior or exterior of a tooth or root surface, a dental implant surface, the interior of an implant crown and / or bridge, and / or any other surface in the oral cavity. The chitosan hydrogel can be applied either non-surgically or during a surgical procedure. The chitosan hydrogel then remains at the application site where it slowly degrades while exerting its antibacterial and / or anti-inflammatory effects. The treatment time with chitosan hydrogel is typically between 20 seconds and 3 minutes per site. The chitosan hydrogel is typically applied to the surface to be treated using a syringe or the like, or with a brush, such as a brush with chitosan bristles as disclosed elsewhere herein. The chitosan hydrogel can be applied during active treatment of periodontal disease and peri-implantitis, but can also be included in home care products.

[0078] The patient being treated is typically a human, although any mammal, such as horses, dogs and cats, can be treated with the chitosan hydrogels according to the present document.

[0079] Chitosan gel can also be used with a brush having bristles that contain or consist of chitosan, as described elsewhere herein. When using such a brush, the brush is gently moved over the surface to which the chitosan hydrogel has been applied, for example to mechanically remove microorganisms or dead tissue. Such treatment can provide a good treatment outcome, since the surface is efficiently cleaned, which, for example, allows connective tissue to better adhere to the tooth and / or implant surface. Thus, this document also relates to the medical applications disclosed herein, which use a brush with chitosan bristles in combination with chitosan hydrogel, as disclosed herein.

[0080] Brushes with bristles containing or consisting of chitosan can be dipped into chitosan hydrogel before using the instrument. The chitosan hydrogel is then applied to the cleaning instrument, particularly to the portion of the instrument that contains a bioabsorbable polymer such as chitosan. The dipping time is typically at least 15 seconds, preferably at least 30 seconds, even more preferably at least 1 minute, and most preferably at least 2 minutes but less than 5 minutes. The dipping time typically does not exceed 30-40 minutes. The instrument is then prepared for use. During dipping, the chitosan portion of the cleaning brush expands and acts as a carrier for the chitosan gel.

[0081] The gel has a long-term effect due to its bacteriostatic properties, so that it remains at the cleansing site after treatment is completed, ie, it is not washed off (see Example 4 in the Experimental section below).

[0082] Experimental Section EXAMPLES

[0083] Preparation and construction of chitosan hydrogels A hydrogel containing chitosan was prepared as follows: 2% acetic acid is prepared by mixing distilled water with 98-100% acetic acid. The pH was monitored to be 2.9 + / - 0.2.

[0084] 4% w / w chitosan (with a low molecular weight between 50 and 400 kDa, and a high degree of deacetylation of >95%) is added to the solution.

[0085] The solution is stirred for 2 hours while being slowly heated to 50°C.

[0086] The mixed solution is filtered through a 125 μm PE filter using a Buchner funnel and a vacuum chamber.

[0087] The solution was then first sonicated for 20 min and then cooled to 20° C. The viscosity and pH were measured at 20° C. The viscosity was between 2000 and 3000 mPas.

[0088] The pH was between 4.1 and 4.7.

[0089] To prepare chitosan hydrogel at pH 3.5, the same procedure was used, but in the first step a 15% acetic acid solution was prepared. EXAMPLES

[0090] Fiber dissolution test In this in vitro experiment, the objective was to test how chitosan fibers dissolve in chitosan hydrogel. One effect of this is that it allows for an increased concentration of chitosan at the site of application of the chitosan hydrogel without the need to increase the concentration of the chitosan hydrogel beyond what is practical to handle (e.g., if the concentration of chitosan in the chitosan hydrogel is too high, it becomes too viscous to be easily applied to a surface).

[0091] The subjective task was to test the hypothesis that chitosan brushes would be a viable carrier for chitosan hydrogel in the treatment of periodontal disease by mechanical and chemical debridement of infected gingival sites.

[0092] Two chitosan solutions were prepared by dissolving 4% chitosan in acetic acid at pH 3.48 and 4.0. Commercially available chitosan brushes (Labrida BioClean®, Labrida AS, Oslo Norway) with working ends made of highly deacetylated (95%) chitosan fibers were placed in four separate vials containing 4 cc of solution: A. Test 1. pH 3.48 n=4, B. Test 2 pH 4.0 n=4, C. Negative Control 1. Water pH 7.0 n=1, D. Negative Control 2, Human Saliva pH 6.8 n=1, E. Negative Control 3: EDTA gel (PrefGel, Straumann AS, Peter Merian-Weg 12, 4002 Basel, Switzerland). The solubility was visually checked at 15 min intervals (see Figures 1-4).

[0093] result The chitosan brush began to dissolve within 5 minutes of starting the experiment.

[0094] Chitosan bristle filaments placed in test group 1 (pH 3.48) were almost completely dissolved after 45 min, whereas filaments placed in test group 2 (pH 4) were completely dissolved after 60-90 min.

[0095] Chitosan bristle filaments placed in the three control groups were intact after 18 hours and showed no signs of dissolution at any time point upon visual inspection.

[0096] conclusion Both pH 3.48 and 4.0 chitosan hydrogels are feasible to combine with brushes containing chitosan fibers. To increase the rate of dissolution, gels with the lowest possible pH are optimal. EXAMPLES

[0097] Mechanical and chemical debridement of dental implants using chitosan brushes and chitosan hydrogels the purpose This study tests a chitosan gel consisting of 4% chitosan containing lactic acid and a pH of 3.86 to evaluate the effect of the gel on adjunctive efficacy when added to mechanical debridement using a chitosan brush alone.

[0098] Materials and Methods 50 Straumann SLA dental implants (D, 4.1 mm, L, 12 mm) Standard Plus, SLA (Straumann Ag, Basel, Switzerland) are included. All implants are received sterile in the original manufacturer's packaging. The implants are randomly assigned to three treatment groups of 10 implants and a negative control (10 implants). The treatment groups and the untreated negative control group are contaminated with a P. gingivalis strain.

[0099] Implant contamination One P. gingivalis strain, A7A1-28(VIR), was grown on blood agar plates under anaerobic conditions for 4 days.

[0100] This P. gingivalis strain was originally provided by AJ van Winkelhoff, The Netherlands, and is part of the material included in the Enersen et al. 2008 paper characterized by MLST and fimA genotyping.

[0101] The strain is dissolved in anaerobic PBS (phosphate buffered saline, pH 7.4) with McFarland 1.8 and 100 μl is transferred to each culture flask, which is incubated anaerobically at 37° C. in a jar (90% N2, 5% H2, 5% CO2) (Anoxomat WS9000, Mart, Lichtenvoorde, The Netherlands) with agitation (50 rpm) together with the implants for 8 days.

[0102] SEM One implant from the control group and the attachment of P. gingivalis strains to the implant surface are confirmed using a scanning electron microscope (SEM) (XL30 EEM, Philips, Eidenhoven, The Netherlands). The implant is fixed in 2.5% glutaraldehyde, dehydrated in a gradient of ethanol, then dried at the critical point, mounted on a metal stud and sputter-coated with a 30 nm thick platinum layer in a Polaron E5100 sputter coater. The SEM was operated at 15 kV.

[0103] Implant Decontamination Implants are instrumented using custom implant holders according to the following standardized protocol: Implants are randomly selected and secured in a vertical position. Each implant is thoroughly rinsed using approximately 20 mL of sterile saline. Instrumentation is performed circumferentially in an apical-cervical direction. Based on pre-study testing, 2 minutes of instrumentation is deemed sufficient for each device to complete decontamination of the implant surface. To prevent contamination, implant holders are rinsed with ethanol and sterile saline before and between each implant instrumentation.

[0104] group 1. Test 1. Chitosan brush alone n=10 (VIR) 2. Study 2. Chitosan brush with 4% sterile chitosan gel at pH 3.86 n=10 (VIR) 3. Positive control, untreated implants n=10 (VIR) 4. Negative control (sterile implants)

[0105] Prior to the main project to calibrate the method, a pilot study was carried out using titanium coins with the following groups: 1. Positive control, untreated implants n=3 2. Chitosan brush alone n=4 3. Chitosan brush with 4% chitosan gel at pH 3.86, n=4 4. Chitosan brush with 90% lactic acid, pH 3.86 5. Chitosan brush + sterile saline rinse with 4% chitosan gel at pH 3.86 n=4 6. Chitosan brush with 4% chitosan alone at pH 5.83, n=4 7. Chitosan brushes with 4% sterile (autoclaved) chitosan gel at pH 3.86, n=4 8. 5. Chitosan brush with PrefGel (EDTA gel, Straumann) + rinse with sterile saline n=4

[0106] The implants are equipped with either a chitosan brush alone or with a chitosan brush containing 4% chitosan gel at pH 3.86 using a rotating brush (Labrida BioClean®, Labrida AS).

[0107] Before use, the sterile packaged brush is soaked in sterile saline or chitosan gel for 2 minutes and then attached to a handpiece with a 1:1 gear connected to a micromotor set at 1500 rpm. Brush gently, parallel to the long axis of the implant. Use a new brush for each implant. Similarly, the handpiece is disinfected with ethanol for each new implant.

[0108] Clean implants are placed in new broth / agar to observe any remaining live bacteria on the implant. Control implants are simply rinsed lightly with the sterile saline provided. Live bacteria are observed on days 1 and 3 by taking aliquots from the broth and transferring them to agar plates (anaerobic incubation) and Eppendorf tubes (for DNA analysis). Implants are further transferred to Eppendorf tubes for DNA / RNA isolation.

[0109] Microbiological sampling, DNA extraction, and qPCR using SYBR green (AriaMx) After instrumentation, DNA is extracted from the implants and quantified by qPCR using known diluted P. gingivalis DNA standards. An AriaMx real-time PCR machine (Agilent) is used. DNA of positive and negative controls with and without P. gingivalis is used as reference values. In each group, the remaining bacterial implant surface DNA is applied as the inverse decontamination determinant. Before DNA extraction, the treated implants are transferred to a tube containing 200 microliters of TE solution (10 mM Tris-HCl and 1 mM EDTA). DNA isolation is performed by Epicentre (MasterPure™ Complete DNA and RNA Purification Kit).

[0110] statistical analysis Bacterial counts are analyzed by comparison to known P. gingivalis DNA standards. Descriptive statistics, median and range of bacterial scores are calculated for each treatment group. As bacterial count results are organized categorically and are not normally distributed, a Kruskal-Wallis rank test is applied to test for overall differences in bacterial reduction between treatment groups. The same test is further used to test for differences in bacterial counts between groups. Parameters Sa, Sds and Sdr were measured from three different sites for each implant. Box plots showing the raw data for the three parameters are displayed. As each implant was measured at three sites, a linear mixed effects model is used. The linear model (assuming normal distribution and identity link function) included a fixed effects section applying dummy coding for the three sites and the four treatment categories. Implant is entered as a random effect to adjust for correlation between different measurements from the same implant. From these analyses, estimated marginal means based on the estimated fixed effects are displayed. Post-hoc analyses for multiple comparisons of differences between treatment groups and sites are adjusted using the Scheffe method. Results were considered statistically significant at P, 0.05. All analyses were performed using Stata version 13 (Stata Corp, College Station, Tex). EXAMPLES

[0111] Effect of pH of hydrogel on cleaning efficiency of titanium coins with chitosan gel and chitosan brush A chitosan brush with chitosan bristles (Labrida BioClean®, Labrida AS) and various decontamination agents were included to evaluate the effect of the decontamination agent on the adjunctive effect when added to mechanical debridement using only the chitosan brush.

[0112] Materials and Methods Sterile titanium coins of 5 mm diameter with a diameter representing a Straumann SLA surface (Straumann AG, Basel, Switzerland) were included. The coins were obtained from Straumann AG. All coins were received in sterile conditions.

[0113] group 1. Positive control, untreated coins n=3 2. Chitosan brush alone n=4 3. Chitosan brush with 4% chitosan gel at pH 3.86 and lactic acid, n=4 4. Chitosan brush with 90% lactic acid at pH 3.86 5. Chitosan brush + sterile saline rinse with 4% chitosan gel at pH 3.86 and lactic acid, n=4 6. Chitosan brush with 4% chitosan alone at pH 5.83, n=4 7. Chitosan brushes, n=4, with 4% sterile (autoclaved) chitosan and lactic acid gel, pH 3.86.

[0114] In the above groups, water was used as the solvent.

[0115] Coin contamination One P. gingivalis strain, A7A1-28(VIR), was grown on blood agar plates under anaerobic conditions for 4 days.

[0116] This P. gingivalis strain was originally provided by AJ van Winkelhoff, The Netherlands, and is part of the material included in the Enersen et al. 2008 paper characterized by MLST and fimA genotyping.

[0117] The strain was dissolved in anaerobic PBS (phosphate buffered saline, pH 7.4) at McFarland 1.8 and 100 μl was transferred to each culture flask, which was incubated anaerobically at 37°C in a jar (90% N2, 5% H2, 5% CO2) (Anoxomat WS9000, Mart, Lichtenvoorde, The Netherlands) with agitation (50 rpm) for 8 days with coins.

[0118] Decontamination of coins The titanium coins were instrumented according to the following standardized protocol: The titanium coins were fixed in a horizontal position with sterile forceps. Instrumentation was performed circumferentially in an apical-cervical direction. Based on pre-study testing, 2 minutes of instrumentation was considered sufficient for each device to complete decontamination of the coin surface. After instrumentation, the coins in group 1 were rinsed again using approximately 20 mL of sterile saline. The coins in groups 2, 3, 4, 6, and 7 were not rinsed, i.e., the decontaminant remained on the surface. The coins in group 5 were rinsed with 20 mL of sterile saline after debridement. To prevent contamination, the forceps were rinsed with ethanol and sterile saline before and between each coin instrumentation.

[0119] The coins were equipped with either a chitosan brush alone, or a chitosan brush with 4% chitosan gel, or 4% chitosan gel with 10% lactic acid, using a rotating brush (Labrida BioClean®, Labrida AS). Before use, the sterile packaged brush was immersed for 2 minutes in either sterile saline or one of the gels (No. 2-7) and then attached to a vibrating handpiece (NSK ER10 / TEQY) connected to a micromotor set at 1500 rpm. The brush was gently applied parallel to the coin. Each side of the coin was applied for 1 minute. The sides of the coin were treated in the same way. A new brush was used for each coin. Similarly, the handpiece was disinfected using ethanol for each new implant. The forceps were sterilized using a Bunsen burner flame.

[0120] After instrumentation (7 different treatments), 2 coins per treatment were transferred directly to an agar plate and 2 coins were incubated in 1.0 ml thioglycollate broth + 5% human blood for 2 (1) days. Then, 20 μl of medium from each well and coins were transferred to a blood agar plate and bacterial colonies were monitored for 3 and 7 days.

[0121] result Microbial growth was visually inspected by a trained and experienced microbiologist after 7 days of growth, and representative photographs were taken (see Figures 5-11).

[0122] [Table 1A]

[0123] [Table 1B]

[0124] Based on the above experiments, it was reported that the use of chitosan brush alone resulted in the retention of bacteria on the titanium coins. The use of chitosan brush supplemented with chitosan gel at pH 3.86 and rinsing with sterile saline, i.e. no gel was left on the titanium surface, did not prevent bacterial regrowth, i.e. no bactericidal effect was reported. Washing with two chitosan gels at pH 3.86 (groups 3 and 7) and the chitosan gel left on the surface prevented further growth where the gel was present, i.e. a bacteriostatic effect was reported. Neither chitosan alone (group 6, pH 5.83) nor lactic acid alone (group 4, pH 3.86) prevented further growth.

[0125] conclusion Based on the above experiments, it was demonstrated that the chitosan gel at pH 3.86 combining the effects of 4% chitosan and lactic acid had a bacteriostatic effect against P. gingivalis. Lactic acid alone or 4% chitosan alone did not provide a bacteriostatic effect.

[0126] Although the present invention has been described with reference to certain exemplary embodiments, this description is intended only to illustrate the concepts of the invention in general and should not be construed as limiting the scope of the invention, which is generally defined by the claims.

Claims

1. 1. A hydrogel comprising chitosan for use in the treatment and / or prevention of oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures, said hydrogel having a pH of from about 2.5 to about 5.

2.

2. 2. The hydrogel for use according to claim 1, wherein the oral inflammatory condition and / or oral infection is periodontal disease, peri-implant disease, oral wounds and / or aphthous lesions.

3. 3. The hydrogel for use according to claim 2, wherein the periodontal disease is periodontitis such as gingivitis, oral mucositis and / or apical periodontitis.

4. 3. The hydrogel for use according to claim 2, wherein the peri-implant disease is peri-implant mucositis and / or peri-implantitis.

5. 2. The hydrogel for use according to claim 1, wherein the oral infection is a bacterial, viral and / or fungal infection.

6. 6. The hydrogel for use according to any one of claims 1 to 5, wherein the hydrogel has a pH of about 2.5 to about 7.0, such as about 3 to about 6, about 2.5 to about 6, about 2.5 to about 5.2, about 2.5 to about 5.0, about 2.5 to about 4.5, about 2.5 to about 4, about 2.5 to about 3.8, about 3 to about 4.5, about 3 to about 4, about 3.2 to about 3.8, or about 2.5 to about 3.

5.

7. 7. The hydrogel for use according to any one of claims 1 to 6, wherein the viscosity of the hydrogel is from about 50 to about 3000 mPaS, such as from about 500 to about 3000, from about 50 to about 2000 mPaS, or from about 100 to about 2000 mPaS.

8. 8. The hydrogel for use according to any one of claims 1 to 7, wherein the concentration of chitosan is from about 2wt% to about 10wt%, such as from about 3wt% to about 9wt%, for example from about 2wt% to about 6wt%, such as from about 2wt% to about 5wt%, for example from about 3wt% to about 6wt%, such as from about 3wt% to about 5wt%, for example from about 3.5wt% to about 4.5wt%, for example about 4wt%.

9. The hydrogel for use according to any one of claims 1 to 8, wherein the molecular weight of the chitosan is between 50 and 1000 kDa, such as between 50 and 600 or between 50 and 400 kDa.

10. 10. The hydrogel for use according to any one of claims 1 to 9, wherein the hydrogel does not contain any additional antimicrobial agents, such as antibiotics, and / or crosslinking agents.

11. 11. The hydrogel for use according to any one of claims 1 to 10, wherein the hydrogel comprises an acid selected from one or more of the acids selected from the group consisting of acetic acid at a concentration of 1 wt% to 10 wt%, hyaluronic acid at a concentration of 0.5 wt% to 10 wt%, formic acid at a concentration of 0.5 wt% to 4 wt%, oleanolic acid at a concentration of 0.5 wt% to 10 wt%, and lactic acid at a concentration of 0.5 wt% to 10 wt%.

12. 10. The hydrogel for use according to any one of claims 1 to 9, wherein the hydrogel consists of water and / or an alcohol such as ethanol as a solvent, chitosan, chlorhexidine, hydrogen peroxide, iodine, and a pH adjuster, such as one or more of the acids selected from the group consisting of acetic acid, hyaluronic acid, formic acid, oleanolic acid, and lactic acid.

13. 13. The hydrogel for use according to any one of claims 1 to 12, wherein the hydrogel consists of chitosan, an aqueous solvent, such as water and / or an alcohol (such as ethanol), and one or more pH adjusting agents, such as lactic acid, acetic acid, formic acid, and / or oleanolic acid.

14. 14. The hydrogel for use according to any one of claims 1 to 13, wherein said hydrogel is used together with a brush comprising bristles comprising or consisting of chitosan.

15. 14. Use of a hydrogel comprising chitosan as defined in any one of claims 1 to 13 in the preparation of a medicament for the treatment and / or prevention of oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures.

16. 14. A hydrogel comprising chitosan as defined in any one of claims 1 to 13 for treating and / or preventing oral inflammatory conditions and / or oral infections and / or for use in endodontic procedures, for application to oral surfaces, such as teeth, tooth roots or dental implant surfaces, of a patient in need thereof.

17. d) a brush as defined in claim 14; e) a hydrogel as defined in any one of claims 1 to 13; f) Optionally, a device, such as a syringe, for applying said hydrogel to an oral surface, such as a tooth surface or a dental implant surface.

18. 14. A hydrogel comprising chitosan as defined in any one of claims 1 to 13.

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