ITMI20131987A1 - TITANIUM OR ITS ANTIBACTERIAL IMPLANT DEVICES - Google Patents

Description

DESCRIPTION

"TITANIUM-BASED ANTIBACTERIAL IMPLANT DEVICES O

ITS ALLOYS "

The present invention refers in general terms to implant devices made of titanium or its alloys, characterized by the fact that they are coated on the surface with an antibacterial composition comprising cations polyhexamethylene biguanide hydrochloride (PHMB), benzalkonium chloride (BZ) and didecyldimethyl ammonium chloride (DDA) .

State of the art

Titanium and its alloys are materials widely used in implantology thanks to their mechanical and biocompatibility characteristics. When exposed to oxygen, titanium tends to oxidize, increasing its intrinsic characteristics that favor osseointegration.

Osseointegration is a process by which the grafted material (implant device or implant) determines an activation of the bone tissue in which it was inserted, such as to determine an adhesion of the bone tissue to the material. The osseointegration process is extremely complex and not fully understood. It involves immunogenic control mechanisms (self recognition), osteoconduction mechanisms (process for which the grafted material represents a support for the new bone production) and osteoinduction (process for which the grafted material determines one or more molecular signals that induce neosynthesis of bone). The osseointegration process can be considered completed in about 60 days, corresponding to the time of consolidation of the fractures.

As for endosseous implants, an important role is played by the effect of the material they are made of, and by the design of the implant itself. In fact, both factors affect the osseointegration process to varying degrees.

Titanium is today the material of first choice for dental and orthopedic prostheses as it combines excellent mechanical properties with high osseointegration.

However, a problem that concerns the previous phase (preoperative phase) to the implantation of a dental and orthopedic prosthesis, both during its storage and handling, is the concrete danger of contamination of the prosthesis itself by microbial loads present in the environment. . In fact, in medical and dental offices, bacteria of various kinds are normally present, which can therefore contaminate the implant and be transmitted to the patient. It is therefore desirable to keep the prosthetic devices free from any microbial contamination for as long a period of time as possible, in order to obtain a better handling of the device itself, without the need to resort to protected environments or particular sanitary precautions.

Therefore, there remains the need to obtain implant devices that combine the required osseointegrative properties with an antimicrobial activity, particularly appreciable especially in the pre-operative phase. The applicants have now found that thanks to the use of a composition comprising the cations: polyhexamethylene biguanide hydrochloride (PHMB), benzalkonium chloride (BZ) and didecyldimethyl ammonium chloride (DDA), it is possible to prepare an antibacterial mixture, useful for coating, by means of adsorption, of implant devices made of titanium or its alloys, keeping the osseointegrative potential of the metal substantially unchanged and also conferring a high antibacterial action.

Summary of the invention

In a first aspect, the invention refers to an implant device in titanium or its alloys coated on the surface by adsorption of an antimicrobial composition comprising: polyhexamethylene biguanide hydrochloride (PHMB), benzalkonium chloride (BZ) and didecyldimethyl ammonium chloride (DDA).

In a further aspect, the invention relates to a process for manufacturing the aforementioned coated implant device, which comprises the surface contact of an implant device made of titanium or its alloys with a composition, preferably hydroalcoholic, containing PHMB, BZ and DDA, followed by possible washing and subsequent drying.

Description of the figures

Figure 1: image of a plate containing the bacterial species S. aureus, E. coli, E. hirae, P. aeruginosa and the fungal species C. albicans, in which an untreated titanium implant is placed.

Figure 2: Image of a plate containing the bacterial species S. aureus, E. coli, E. hirae, P. aeruginosa and the fungal species C. albicans, in which a titanium implant of the present invention is placed, coated using a composition hydroalcoholic (ethanol / water) comprise DDA 5%, BZ 5% and PHMB 10%. The stay in the plate was prolonged for 60 minutes.

Figure 3: image relating to a condition equal to that used in Figure 2, in which the stay in the plate was prolonged for 120 minutes.

Detailed description

“Percent by volume” (% v / v) indicates the quantity by volume of the single component with respect to the final volume of the antibacterial composition. Similarly, “percentage by weight” (% w / w) indicates the weight of the single component with respect to the final weight of the composition.

In one embodiment, the present adsorption-coated implant device is obtained by means of a process which involves the use of a hydroalcoholic mixture in the form of a solution comprising water and suitable alcohol, in which the antibacterial organic cations PHMB, BZ, have been dissolved. and DDA. In this regard, the term "solution" is intended to indicate a liquid phase which is substantially homogeneous and free of background bodies or precipitates.

The implant device (or implant) made of titanium or its alloys of the present invention is characterized in that it is coated on the surface by adsorption of organic cations: polyhexamethylene biguanide hydrochloride (PHMB), benzalkonium chloride (BZ) and didecyldimethyl ammonium chloride (DDA).

The benzalkonium chloride product (CAS No. 63449-41-2), has the following general structural formula:

wherein the group R is a linear or branched alkyl group having from 8 to 18 carbon atoms.

Polyhexamethylene biguanide (CAS No.32289-58-0) has the following general structural formula:

while didecyl dimethyl ammonium chloride (CAS No. 7173-51-5), has the following structural formula:

These substances are characterized by a powerful bactericidal effect with a broad spectrum of action and low toxicity. Their probable mechanism of antibacterial action consists in the destruction of the cell membrane of the microbial species. BZ, DDA and PHMB are commercial products, available both as a solid and in aqueous solution, which can both be used in the preparation of the present plant, as described and claimed herein.

As mentioned above, the Applicants have surprisingly found that the organic cations of DDA, BZ and PHMB can be used for the realization of an antibacterial composition, to be used for the stable coating (total or even partial) of the surface of an implant device in titanium or its alloys, by adsorption. In this way, the resulting device has both osseointegrative properties and a high antimicrobial activity, useful in order to reduce the possibility of contamination from external agents, especially in the preoperative phase.

Advantageously, in fact, the coated device of the invention is able to stably adsorb the indicated cations, maintaining its antimicrobial activity for a long period of time, even more than 30 days from the deposition of the coating. The device, therefore, can also be prepared several days before its use, without the need for special conditions or storage treatments. The Applicants have also noted that the present adsorption-coated implant maintains an acceptable condition of sterility for several months, even if it is left in the presence of microbial contaminants normally present in the environment of use, such as in medical and dental surgeries.

In a preferred embodiment of the invention, the implant device has an adsorbed surface with BZ and DDA in a total concentration between 1% and 25% w / w, and PHMB in a concentration between 2% and 10% w / p.

In a particularly preferred form, the surface comprises BZ, DDA and PHMB adsorbed in quantities ranging from 5 to 10% w / w, being even more preferred values of BZ and DDA of 5% and of PHMB of 10%.

Furthermore, the three organic cations indicated can be present in the coating composition (and therefore on the implant surface) in a 1: 1: 1 ratio to each other, or preferably in the presence of an excess of PHMB, even more preferably in a 2: 1 ratio. compared to DDA and BZ. In this way, the antimicrobial activity of the coating composition is able to perform its function very quickly, and to keep it substantially unchanged even for months, as supported for example by the enclosed experimental part.

Preferably, the present device is completely coated (intended for at least 99% of its surface) or even partially (intended for a surface area between 1 and 99%), depending for example on the type of device and the applications to which can be destined.

In a further aspect, the invention refers to the present implant device in the form of: dental, orthopedic implant, connection screws and transcutaneous and transmucosal parts. Preferably the device is a dental or orthopedic implant, even more preferably a screw. In this regard, the following are particularly preferred: healing screws (which are temporarily applied, by screwing them, on the implanted dental root, whose purpose is to promote healing and adaptation of the soft gingival tissues that will surround the final dental crown) ; cap screws (or healing screws that are placed inside the implant at the end of placement and which serve as a guide to the gingiva for the healing of the tissues above the implant itself in the healing phase); connecting screws that secure the abutments to the implants with the aim of obtaining an antimicrobial effect within the implant-abutment connection.

In an equally preferred embodiment, the present implant device is in the form of: abutment (or stump, in dentistry identifies the prosthetic part detached and emerging from the gingiva of an intraosseous implant); monophasic implant in the transmucosal and prosthetic part; prosthetic part, typical for example of metal structures that support prosthetic crowns; orthopedic screw in the transcutaneous part; orthopedic, maxillofacial and dental-orthodontic distractor for the transcutaneous and trans mucosal part, and implantology surgical set in general. In any case, the coated device of the invention is able to maintain its antimicrobial activity substantially unchanged over time, even for periods longer than a month, without the need for specific storage or maintenance conditions. In this way, the implant can be handled by the operator with more peace of mind and in hygienic and sanitary conditions typical of the medical environment in which this device is implanted.

In support of this, the accompanying figures clearly show that when an uncoated titanium prosthesis is immersed in a bacteria-rich environment, no antibacterial effect is observed (Figure 1). On the contrary, when a titanium coated implant according to the present invention is immersed in the same environment, for times of 60 and 120 minutes (Figures 2 and 3), a high antibacterial action is observed, which lasts over time and allows its use. of the plant safely and continuously coated.

In a further aspect, the invention also refers to a process for manufacturing the aforementioned coated implant device, which comprises contacting the starting device based on titanium or its alloys with a composition comprising: polyhexamethylene biguanide hydrochloride (PHMB ), benzalkonium chloride (BZ) and didecyldimethyl ammonium chloride (DDA), followed by possible washing and subsequent drying. Preferably, said contact occurs by immersion of the device in a solution comprising the aforesaid compounds, even more preferably, in a hydroalcoholic solution.

Therefore, in one embodiment, the invention refers to a process for the realization of the present implant device, which includes the steps of:

a) surface contact of an implant device made of titanium or its alloys with a solution, preferably hydroalcoholic, containing BZ, DDA and PHMB;

b) possible washing of the surface of the treated device;

c) drying of the surface of the device obtained.

As mentioned above, in a preferred form of the process, step a) takes place through the use of a hydroalcoholic mixture comprising BZ, DDA and PHMB, intended to include water and at least one alcohol having from 1 to 6 carbon atoms, even more preferably ethanol or isopropanol. In one embodiment, therefore, the present implant device made of titanium or its alloys is characterized in that it is obtained (or obtainable) by coating with a hydroalcoholic antimicrobial composition, preferably water / ethanol, comprising PHMB, DDA and BZ, the latter still more preferably in the concentrations indicated above.

In this regard, hydroalcoholic mixtures comprising alcohol and water in a ratio ranging from 1: 1 to 1: 3 are particularly preferred, being particularly preferred percentages by volume with respect to the total volume of alcohol ranging from 20% to 60% v / v.

In a further embodiment, step a) of the present process takes place by immersion of the device, even more preferably using a composition in the form of a hydroalcoholic solution comprising ethyl alcohol 50% v / v and water 30% v / v. Typically depending on the concentration of the hydroalcoholic solution used, the surface coating can take place by immersion, for example for a time between 10 and 180 minutes, at room temperature, understood as between 15 and 40 ° C.

Optionally, at the end of step a) the treated device is subjected to washing with an alcohol having from 1 to 6 carbon atoms, preferably with ethyl alcohol or isopropyl alcohol. In this way it is possible to eliminate the excess of the PHMB, DDA and BZ components that are not directly adsorbed on the implant surface. After any washing, the coated device is subjected to step c) of drying, which can be carried out for example by air flow, preferably at temperatures between 20 and 60 ° C. In this way it is possible to eliminate alcohol and / or water residues, allowing the permanent and stable adsorption over time of the BZ, DDA and PHMB cations on the surface of the device.

In this regard, it should be noted that the quantity of BZ, DDA and PHMB that cover the plant can be calibrated by changing the concentration of the solution and / or the treatment times, it being understood that higher concentrations and / or longer times allow the coating the implant with a higher quantity of BZ, DDA and PHMB. Further features and advantages of the invention will become clearer from the description of some examples of embodiment, given below for indicative and non-limiting purposes.

EXPERIMENTAL PART

Example 1: XPS analysis of titanium implants treated with alcoholic solutions of BZ, DDA and PHMB.

The XPS analysis of the surface clearly highlights the surface grafting of the organic substance, witnessed by the increase in species N and C, well above the atomic concentrations already present on the control sample (white).

The 5-hour coating time does not significantly change the atomic concentrations of the N and C species, already detected after 3 hours of coating.

Preparation of the device of the invention

A preliminary test was performed by immersing 1 cm <2> titanium platelets in hydroalcoholic solutions containing respectively 10% w / w DDA, 10% w / w BZ, and 10% w / w PHMB, for a time equal to 45 minutes in order to check the adsorption capacity of the various antimicrobial active ingredients on the titanium surface. The platelets were then immersed in ethyl alcohol for 5 minutes and then dried in an air stream at 50 ° C.

Table 1: data obtained, expressed in atomic% and the energetic position of the Binding Energy, B.E. in electron volts (eV).

% Atomic

Ti2p C1s N1s 01s (B.E.eV)

Ti white 18.4 20.4 1.9 58.2

(459) (285.5) (401) (530.5)

DDA 10.7 35.5 10.0 37.9

(459) (286) (400.5) (531)

PHMB 10.9 34.8 9.5 40.8

(459.5) (286) (400.5) (531)

BZ 10.0 34.1 9.2 41.7

(459) (286) (400.5) (531)

The table clearly shows the increase in the concentration of both C and N in the treated samples with respect to the control Ti (C from 20 to about 35; N from 2 to about 10). The energy positions of the relative electronic levels do not vary significantly within 0.5 eV.

Tests were then performed by immersing titanium platelets in alcoholic solutions containing the mixture of the three active ingredients in w / w concentration equal to: DDA, 5%, BZ 5% and PHMB 10% for times of 1 h, 3h, and 5 h.

Table 2: results in atomic% showing the absorption of antimicrobial organic cations.

ATOMIC CONCENTRATION

white EtOH EtOH EtOH

1 hour 3 hours 5 hours

C1 23.33 45.33 58.05 57.73

N1 6.89 14.70 24.78 25.29

01 45.97 24.35 7.43 6.77

Ti1 10.20 2.85 0.00 0.00

Si2 9.78 8.09 4.20 4.37

AI2 3.03 1.18 0.00 0.00

CI1 0.58 3.44 5.54 5.84

Zn1 0.22 0.06 0.00 0.00

100.00 100.00 100, 00 100.00 In table 2, the ETOH indication 1 hour, 3 hours and 5 hours refers to the immersion times of titanium implants in solutions having the following composition:

ethyl alcohol 50% v / v, water 30% v / v, BZ 5% w / w, DDA 5% w / w, PHMB 10% w / w.

In all cases, after the organic cation adsorption phase, the platelets were washed by immersion in ethyl alcohol for 5 minutes and subsequent drying in an air stream.

It is observed that the surface of the white sample shows the presence of Al and Zn contaminations, which are covered by the deposited organic component, as well as in the case of titanium (Ti) which is no longer visible after 3 hours of treatment. Si and Cl are also present, the latter increasing with the deposition of the organic component.

Example 2: Evaluation of the antimicrobial activity of titanium implants treated with the composition of the invention.

Dental implants treated with a solution containing 50% v / v ethyl alcohol, 30% v / v water, 5% w / w BZ, 5% w / w DDA, 10% w / w PHMB, and left to soak for equal to 60 and 120 min, followed by washing in ethyl alcohol and drying in a current of air, they were subjected to microbiological analysis in order to evaluate the microbicidal activity of the coating created on their surface.

The antimicrobial activity was evaluated against the following microorganisms: Escherichia coli, Staphyloccoccus aureus, Pseudomonas aeruginosa, Enterococcus hirae, Candida albicans.

Example 3. EXPERIMENTAL PROCEDURE

3.1 TEST SYSTEM

Microorganisms

The following test strains were used:

Pseudomonas aeruginosa ATCC 15442

Staphylococcus aureus ATCC 6538

Escherichia coli ATCC 10536

Enterococcus hirae ATCC 10541

Candida albicans ATCC 10231

The strains come from Diagnostic International Distribution SpA.

The bacterial strains were kept frozen in culture broth and 50% (v / v) glycerol; before use they were transplanted on TSA slants and stored in the refrigerator at 4 ° C ± 2 ° C.

Candida albicans was kept frozen in culture broth and 50% glycerol.

(v / v); before use it was transplanted onto Malt Extract Agar slant and stored in the refrigerator at 4 ° C ± 2 ° C.

3.2 CULTURAL LANDS AND REAGENTS

Land

Tryptone Soya Agar (TSA) for bacterial strains and Malt Estract Agar (MEA) for Candida albicans.

Diluent

Tryptone, digestion

pancreatic casein 1.0 g OXOID

NaCl 8.5 g MERCK

Distilled water to taste 1000 ml

3.3 EQUIPMENT

- KW oven for dry sterilization

- COLUSSI steam autoclave

- MEMMERT thermostat

- VELP Vortex stirrer

- VWR stopwatch

- THERMO SCIENTIFIC micropipettes

3.4. EXECUTION OF THE ASSAY

Preparation of test suspensions

The bacterial strains and the Candida albicans strain, once thawed, were transplanted twice in a row on TSA slants (MAE for Candida albicans) and incubated at 37 ° C ± 1 ° C for 18 hours, obtaining the culture of work. Within 2 hours of starting the test, the working culture was suspended in diluent using glass beads and the suspension was diluted to a count of 1.5 x 10 <6> to 5.0 x 10 <6> cfu / ml ( trial suspension). Test suspension count

Serial dilutions in diluent up to 10 <-5> - 10 <-6> of the test suspensions having concentrations from 1.5 x 10 <6> to 5.0 x 10 <6> cfu / ml were carried out. A double count was performed for inclusion in Agar. The number of cfu / ml of the suspension was determined after an incubation period of 24 hours at 37 ° C ± 1 ° C.

Dental implant coatings

The coatings were made with the following procedure:

1) washing of the systems with distilled water

2) coating with the antimicrobial solution containing ethyl alcohol 50%, water 30%, BZ 5%, DDA 5% PHMB 10% with immersion times of 60 minutes and 120 minutes

3) washing by immersion in ethanol for 5 minutes.

4) drying in a current of air.

Execution of the essay

For each strain of microorganisms, a test tube containing 5 ml of test suspension with a concentration between 1.5 x 10 <6> and 5.0 x 10 <6> cfu / ml was prepared. Subsequently, 1 ml was taken from each tube and placed in a single tube which therefore contains, at the end of the procedure, a mixture of all the strains of the microorganisms having a concentration in the range 1.5 x 10 <6> - 5.0 x 10 <6> cfu / ml.

The treated and untreated dental implants were immersed in the test mixes, containing the microbial species, and extracted after 30 seconds. The samples were left under a sterile hood in contact with the air for a time equal to 5 minutes. At the end of this time, the implants were placed in Petri dishes and covered with liquid culture medium, maintained at a temperature of 50 ° C. The Petri dishes were stirred for 1 minute, in order to favor the homogeneous diffusion in the whole plate of microorganisms adhered to the surface of the samples and the medium was then allowed to solidify. The Petri dishes were finally placed in an incubation cell at 37 ° C for 24 hours.

After this time the plates were examined by evaluating the development of bacterial and fungal colonies.

Example 4: RESULTS

Preliminary essay

Table 3 - Concentration values (cfu / ml) of the test suspensions

CONCENTRATION OF MICROORGANISMS TEST SUSPENSION TEST (cfu / ml) Staphylococcus aureus (ATCC 6538) 3.71x10 <tì> Pseudomonas aeruginosa (ATCC 15442) 2.18x10 <tì> Escherichia coli (ATCC 10536) 1.94x10 <hirae 41> Enterococcus ) 1.70x10 <tì> Candida albicans (ATCC 10231) 3.26x10 <tì>

Real essay

The images in Figures 1, 2 and 3 represent the development of plates where the dental implants treated with the procedure described above were placed and not treated after contact with the test mixture containing the bacterial species S. aureus, E. coli, E. hirae, P. aeruginosa and the fungal species C. albicans.

As shown in the images of Figures 1-3, the dental implants of the invention coated with the mixture DDA, BZ, PHMB demonstrate a high antimicrobial activity, inducing the total mortality of the microbial cells. The activity was observed unchanged for implants immersed in the antimicrobial solution for 60 or 120 min.

It should be noted that the implant in Figures 1-3 was immersed in extremely concentrated solutions of microorganisms (> 10 <6> cfu / ml) and therefore the surface of the implant device came into contact with millions of microbial cells. The high antimicrobial activity was verified for all the test strains considered and was also confirmed 30 days after the initial treatment.

It is evident that the antimicrobial cations adsorb stably on the surface of metal implants made of titanium, giving their surface a high microbicidal property, which remains unaltered for considerable times from application, while keeping the implants exposed to contamination deriving from the species. environmental microbes.

Claims (13)

CLAIMS 1. Implant device made of titanium or its alloys, coated on the surface by adsorption of an antimicrobial composition comprising: polyhexamethylene biguanide hydrochloride (PHMB), benzalkonium chloride (BZ) and didecyldimethyl ammonium chloride (DDA). 2. Implant device according to claim 1, having an adsorbed surface with BZ and DDA in a total concentration of between 1% and 25% w / w, and PHMB in a concentration of between 2% and 10% w / w. weight. Implant device according to claim 2, having an adsorbed surface with BZ and DDA in a concentration of 5% respectively, and PHMB of 10% w / w. 4. Device according to any one of the preceding claims, adsorbed for at least 90% of its surface. 5. Device according to any one of the preceding claims in the form of: dental, orthopedic implant, connection screws, transgingival and transgingival parts. 6. Device according to claim 5, in the form of: healing abutment; screw cap; connecting screw, abutment, monophasic implant in the transmucosal and prosthetic part, prosthetic part, orthopedic screw in the transcutaneous part, orthopedic, maxillofacial and dental-orthodontic distractor for the transcutaneous and transmucosal part. 7. Process for manufacturing the implant device according to any one of claims 1 to 6, which comprises the steps of: a) surface contact of an implant device made of titanium or its alloys with a solution, preferably hydroalcoholic, containing BZ, DDA and PHMB; b) possible washing of the surface of the treated device; c) drying of the surface of the device obtained. 8. Process according to claim 7, wherein the surface contact of step a) occurs by immersing the device in said solution. 9. Process according to claim 7 or 8, wherein the hydroalcoholic solution of step a) is a solution comprising: water, at least one alcohol having from 1 to 6 carbon atoms, PHMB, DDA and BZ. 10. Process according to any one of claims 7-9, wherein said alcohol is present in quantities ranging from 20% to 60% v / v. 11. Process according to any one of claims 7-10, wherein said alcohol is ethanol or isopropanol. 12. Process according to any one of claims 7-11, wherein the hydrolacolic solution of step a) is a solution comprising: water 30% v / v, ethanol 50% v / v, DDA 5%, BZ 5%, PHMB 5 % or 10% w / w. 13. Process according to any one of claims 7-12, in which the drying step c) is carried out by means of air flow at temperatures between 20 ° C and 60 ° C.