A NANO-hydroxyapatite produced in the presence of chitosan

Abstract

The invention relates to a nano-hydroxyapatite composition added to chitosan for use after the tooth bleaching process.

Description

[0001] DESCRIPTION

[0002] A NANO-HYDROXYAPATITE PRODUCED IN THE PRESENCE OF CHITOSAN Technical Field

[0003] The invention relates to a nano-hydroxyapatite composition added to chitosan for use after the tooth bleaching process.

[0004] Background

[0005] As aesthetic anxiety has become more and more important for individuals, the interest in aesthetic practices in dentistry has also increased. Tooth bleaching treatment is one of the leading aesthetic and medical applications in dentistry. Although bleaching treatments produce satisfactory aesthetic results, various applications are needed to treat the changes in the hard tissue of the tooth during and after the treatment of the bleaching process and the negative consequences of these changes.

[0006] Today, new bleaching products and technologies such as nano-additives and alternative carrier systems are being developed. These products and technologies can be effective in maximizing the bleaching benefits by minimizing the structural damage of tooth enamel by accelerating the bleaching reaction. Remineralizing agents such as fluoride, potassium nitrate, amorphous calcium phosphate (ACP), chitosan and hydroxyapatite can be used in the treatment of adverse effects on the enamel surface after tooth bleaching.

[0007] Tooth bleaching treatment is the most conservative treatment method for colored teeth compared to restorative treatment methods. Vital bleaching treatment can be performed by the dentist in the office environment using agents containing high concentrations (25%-40%) of hydrogen peroxide (HP) or carbamide peroxide (CP), or it can be applied in the home environment by the patient under the control of the physician using a lower concentration (3%-7%) of hydrogen peroxide or (6%-20%) of carbamide peroxide. Although there are many different bleaching procedures, they are all based on a common chemical reaction and this reaction is HP's transformation into unstable free radicals as a result of the degradation of peroxides and breaking down large pigment molecules by oxidation-reduction reactions.

[0008] In studies examining the effects of bleaching treatment on enamel surfaces in the literature, effects such as increased porosity, demineralization, decrease in protein concentration, loss of calcium, decrease in surface microhardness and change in Ca / P ratio have been reported. The enamel structure consists of 97% HA crystals with a size of 20-40 nm. A study reported the strong affinity, biocompatibility and restorative capacity of 20 nm-sized artificial HA applied to eroded human enamel.

[0009] Recent interest in nanotechnology in many fields has paved the way for the use of nanohydroxyapatite (n-HA) in dentistry, which offers crystals ranging in size from 50 to 1000 nm.

[0010] In the current system, there are articles with various patent and utility model applications in the relevant field. The article titled "Effects of bleaching gel containing T iO2and chitosan on tooth surface roughness, microhardness and colour" explains the effects of an experimental bleaching gel made with TiO2Opalescence Boost PF and Philips Zoom bleaching agents and chitosan on tooth surface roughness, microhardness and color. In this document, it was determined that the low-concentration (6% HP) experimental gel containing T iO2and chitosan provided effective tooth bleaching and did not cause any negative effects in terms of tooth surface roughness and microhardness. It is stated that the use of TiO2and chitosan provides clinicians with the advantage of using lower HP concentrations by avoiding unwanted side effects.

[0011] In the article titled "In-Office Tooth Bleaching With Chitosan-Enriched Hydrogen Peroxide Gels: In Vitro Results", the addition of chitosan in the bleaching agent and its results are explained. It is emphasized that calcium, amorphous calcium phosphate and synthetic hydroxyapatite are recommended to minimize the specified adverse effects. Different active principles are added to bleaching gels to prevent (or reduce) demineralization events or tooth sensitivity that occur during bleaching treatments. In this sense, biopolymers are characterized as they may have remineralizing or anti-erosive potential.

[0012] In the article titled "Enamel changes of bleached teeth following application of an experimental combination of chitosan-bioactive glass", the side effects of tooth bleaching and the damage it causes to the tooth surface are mentioned. It describes the use of chitosan-added bioactive glass to eliminate these effects. It is emphasized that the results of studies on the combination of chitosan with other materials such as hydroxyapatite and amelogenin are promising, and it may be appropriate to add chitosan directly to bleaching agents to reduce complications without a negative effect on tooth color change.

[0013] Brief Description and Objects of the Invention The invention relates to a chitosan-doped nano-hydroxyapatite composition for application after the tooth bleaching process.

[0014] With the invention, it is ensured that the bleaching agent containing nohydroxyapatite significantly increases the microhardness of the tooth enamel surface and reduces the roughness. After bleaching treatments, it is ensured that the use of experimental nanohydroxyapatite gel increases microhardness and reduces roughness without affecting color change.

[0015] With the invention, the Ca / P ratio on the tooth surface was increased without changing the bleaching efficiency. In addition, positive effects were achieved in microhardness and surface roughness values.

[0016] Descriptions of the Figure

[0017] Figure 1 : A view of the characteristic diffraction peaks of the n-HA sample.

[0018] Figure 2: A SEM image of n-HA crystals with chitosan added.

[0019] Figure 3: SEM images of samples from normal enamel surface (control AB), Group B (C, D), Group O (E, F), Group Bn (G, H), Group On (I, K) at lOOOx (left) and 5000x (right) magnification.

[0020] Figure 4: A comparison of average surface roughness values before and after bleaching and groups (Ra).

[0021] Figure 5: A comparison of microhardness values before and after bleaching and groups.

[0022] Figure 6: SEMZEDS point analysis images of the particles seen on the tooth surface.

[0023] Figure 7: An element analysis (%) graph of the particles seen on the tooth surface.

[0024] Figure 8: A graphical analysis of O, F, Na, P, Cl and Ca elements (%) on tooth surfaces.

[0025] Detailed Description of the Invention

[0026] The invention relates to a nano-hydroxyapatite composition added to chitosan.

[0027] For chitosan-added nano-hydroxyapatite, n-HA synthesis was performed first. Here, nanosize HA particles were obtained by the high-temperature oxidation method using HA in the micro dimension. Chitosan was used as an additive in the production of n-HA.

[0028] 88% by weight of titanium powder, 2% chitosan (additive) and the rest (10%) were complemented with distilled water and mixed thoroughly in a sonic and magnetic stirrer for 15 minutes and 1 hour until the solution was homogeneous. It was then allowed to dry for 24 hours in an 80°C oven.

[0029] Solutions were removed from the oven at 10°C / min. It was quickly incinerated in a high-temperature ashing furnace at 800°C for 30 minutes. Characterization of synthesized nanohydroxyapatite powders was carried out with XRD and SEM devices.

[0030] The sample obtained was confirmed to be n-HA in the XRD characterization experiment. Figure 1 shows the characteristic diffraction peaks of the n-HA sample. It has been observed that the crystal structure in the figure corresponds exactly to the characteristic index values defined by the file number (JCPDS no. 09-0432) determined for HA by the Joint Committee on Powder Diffraction Standards (JCPDS). In addition, it was observed that the HA particles were nanoscale. It is seen in Figure 2 that the size of the particles produced by n-HA by adding chitosan is less than 50 nm.

[0031] Thanks to the invention, it has been concluded that the application of nano-hydroxyapatite in the presence of chitosan increases the microhardness value on the enamel surface and reduces the surface roughness, as can be seen from Table 1, it contributes to the Ca / P ratio, shows non-homogeneous accumulation on the surface, has no negative effect on the aesthetic result and reduces the surface demineralization.

[0032]

[0033] Table 1: A demonstration of the effects of nano-hydroxyapatite application in the presence of chitosan

[0034] In order to form the groups mentioned in Table 1, 52 upper anterior teeth were randomly divided into 4 groups. These groups are as follows:

[0035] Group B: Biowhiten in-office 40% n-Hp application.

[0036] Group O: Opalescence Boost PF 40% HP application (n-HA-free)

[0037] Group Bn: Experimental n-HA gel application after Biowhiten in-office 40% n-HP application.

[0038] Group On: Experimental n-HA gel application after Opalescence Boost PF 40% HP application. Initial color, enamel surface roughness and microhardness measurements of 10 teeth from each group were performed. One tooth that was not treated and two tooth samples that were treated from each group were reserved for SEMZEDS analysis. Other measurements of the samples were repeated immediately after bleaching and one week after the bleaching process. In this process, the teeth were kept at room temperature in light-proof containers containing distilled water.

[0039] The teeth divided into groups were rinsed with distilled water after the initial measurement. BioWhiten in-office n-HP bleaching gel was activated by mixing at the tip of the tube. Afterwards, it was applied to cover the tooth surface completely and to be 0.5-1 mm thick. In accordance with the manufacturer's instructions, the gel was kept on the tooth surface for a total of 40 minutes 4 times in 10-minute sessions. Then, the excess of the gel on the tooth surface was wiped with the help of a cotton roll and the surfaces were rinsed with distilled water so that there was no more gel on the tooth surface.

[0040] Afterwards, Opalescence Boost PF 40% bleaching gel was mixed with 50 times (25x2) back and forth movements to be activated. All activated gel was collected in a tube and then applied to the tooth surfaces to cover the entire buccal surfaces of the tooth, to be 0.5 mm-1 mm thick. The gel was kept on the tooth surface for a total of 40 minutes in 2 sessions of 20 minutes. When the process was completed, the excess of the gel on the tooth surface was wiped with the help of a cotton roll and the surfaces were thoroughly rinsed with distilled water.

[0041] Within the scope of the invention, n-HA powder with chitosan added was mixed with phosphate-buffered saline solution, which will act as a carrier to apply it to the tooth surface, at a ratio of Iml / lg and brought to a gel consistency. After bleaching was applied to Group Bn and Group On samples, the produced n-HA gel was applied to the tooth surface with the help of a bond brush to cover the buccal surface of the tooth. Then, it was adapted to the tooth surface by making round movements with a bond brush and a round brush. The n-HA gel was kept on the tooth surface for 5 minutes and then the teeth were rinsed with distilled water.

[0042] Color analysis was also carried out to show the effect of the use of n-HA powder with chitosan added developed with the invention. The L* a* b* values obtained as a result of the measurements made before bleaching, immediately after bleaching and 1 week after bleaching were recorded. The L* a* b* values measured at baseline and immediately after bleaching (L0-Ll), baseline, and 1 week after bleaching (L0-L3) were calculated in the CIEL* a* b* system in terms of the AE value, which indicates the degree of perceived color difference between the two bodies. In the calculation, L' a' b' values measured before and immediately after bleaching were also analyzed according to the results obtained using the formula AE = ((AL)2 + (Aa)2 + (Ab)2) Vi. The AE values of each group before bleaching, immediately after the bleaching process and 1 week after the bleaching process are shown in Table 2.

[0043] Color Change (AE) AE1 AE2

[0044] (L0-L1) (L0-L2)

[0045] Group B 3.215+0.983 2.874±0.734 Group 0 3.302+0.910 2.699±0.774 Group Bn 3.216±0.406 2.865+0.358 Group On 3.200+0.401 2.795+0.425

[0046] p20.992* 0.928* Table 2: AE values of the groups before bleaching, immediately after bleaching and 1 week after bleaching

[0047] The AE1 value obtained as a result of the measurements made immediately after the initial bleaching is 3.2; the AE2 value obtained as a result of the measurements made one week after the initial bleaching is 2.7. The values obtained according to the NBS system used to determine the relationship between the amount of color change recorded in a spectrophotometer and the clinical environment were found to be 2.94 for the AE1 value and 2.48 for the AE2 value. According to the NBS criteria, these values indicate a clinically visible color change.

[0048] When the color change of the treatment groups was compared, no statistical difference was observed between the groups (p>0.05). There was no difference between the color changes of the groups measured immediately after bleaching and 1 week after bleaching (p>0.05).

[0049] The roughness values of the tooth surfaces were evaluated in Ra before bleaching, immediately after the application of the bleaching process and 1 week after the application of the bleaching process. The mean surface roughness values of the groups and the differences between the groups are shown in Table 3 and Figure 4. Surface roughness Before bleaching immediately after 1 week after p1(Ra) bleaching bleaching

[0050] Group B 0.097±0.02 0.126±0.019A0.124±0.019A0.075* Group O 0.093±0.016a0.153±0.018bB0.152±0.019bB<0.001* Group Bn 0.129±0.073 0.117±0.011A0.114±0.011A0.123* Group On 0.107±0.015 0.122±0.016A0.120±0.015A0.376

[0051] p20.202* <0.001* <0.001*

[0052] Table 3: Statistical mean surface roughness and standard deviation values of the groups before and after bleaching (Ra)

[0053] pl: Intertemporal p* value, p2: Intergroup p* value

[0054] *The same lowercase letters on the same line indicate similar times.

[0055] *The same capital letters in the same column indicate similar groups.

[0056] When the post-bleaching test groups were compared, an increase in Ra value was observed only in Group O (p<0.05). No significant difference was observed in Ra values in the measurements made immediately after bleaching between Group B, Group Bn, and Group On (p>0.05). Group On showed a statistically lower Ra value than Group O. (p<0.05). In the measurements made immediately after the application of the bleaching process and 1 week later, no statistically significant difference was found in terms of Ra values in all groups.

[0057] The microhardness analyses of the groups were evaluated before bleaching, immediately after the application of the bleaching process and 1 week after the application of the bleaching process. The microhardness values and statistical differences of the groups are shown in Table 4 and Figure 5.

[0058] Microhardness Before bleaching immediately after 1 week after p1

[0059] bleaching bleaching

[0060] Group B 322.40±10.85a294.20±9.83bA301.30±13.65bA<0.001* Group O 316.07±6.72a274.07±11.41bB275.60±13.14bB<0.001* Group Bn 325.53±7.77a316.80±8.40bc310.20±8.14bc<0.001* Group On 324.23±12.49a312.27±13.05bc308.37±13.04bc<0.001* p20.155* <0.001* <0.001*

[0061] Table 4: Statistical mean and ± standard deviation values of the microhardness values of the groups before and after bleaching.

[0062] No statistically significant difference was observed between the groups in terms of microhardness values of the teeth before bleaching (p>0.05). A decrease in the microhardness value was observed on the tooth surfaces in all groups immediately after the bleaching process (p<0.05). Group O showed the lowest microhardness value after the bleaching process (p<0.05). Group Bn showed a statistically higher microhardness value than Group B (p<0.05). Group On showed a statistically higher microhardness value than Group O (p<0.05). In the measurements made immediately after bleaching and 1 week after bleaching, no significant difference was found in terms of microhardness value. (p>0.05)

[0063] Samples from unbleached enamel surface (control) and treatment groups were examined in SEM-EDS devices at 10 kV voltage, lOOOx and 5000x magnification. The images obtained are shown in Figure 3.

[0064] Parallel abrasion lines formed by the polishing process are seen on all tooth surfaces. Group O showed a more irregular surface and crack-like formations along the surface compared to Group B (Figure 3-E, F). When Group B and the untreated enamel surface were compared, it was observed that some particles clustered on the tooth surface in Group B at x5000 magnification (Figure 3-D). It was observed that the tooth surfaces of Group Bn and Group On, to which experimental n-HA gel was applied after the bleaching agent, were smoother and covered with a thick layer compared to Group O (Figure 3-H, Figure 3-K). At higher magnifications (x5000) on Group B, Group Bn, and Group On surfaces, it is seen that single and clustered particles adhere to the enamel surface (Figure 3-D, Figure 3-H, Figure 3-K). The distribution of these particles is not homogenous. Point analysis was performed on the particles that were seen to accumulate on the tooth surface in these groups. SEM images and EDS elemental content (%) of the particles displayed as a result of this analysis are given in Figure 6 and Figure 7.

[0065] Ca, P, and O chemical elements were found in the particles examined in the EDS point analysis. These elements were found to be compatible with the elements in the formula Cal0(PO4)6(OH)2 of the HA structure. In addition, the size of these particles is <50 nm. For this reason, the particles seen belong to the n-HA structure. For all groups, the chemical composition of tooth enamel in terms of O, F, Na, P, Cl and Ca elements % by weight and Ca / P ratio was analyzed using EDS. The weight (%) ratios and Ca / P ratio of the concentration values of the chemical elements observed as a result of the SEMZEDS analysis of the tooth surfaces of all groups are shown in Table 1 and Figure 8 given above. The lowest Ca / P ratio was observed on the tooth surface of Group O. A higher amount of Ca and P was observed on the tooth surface of Group B compared to Group O. It was observed that the amount of Ca and P increased in Group Bn and Group On, to which experimental n-HA gel was applied.

[0066] As can be seen, after the application of two different bleaching agents with and without nanohydroxyapatite, the effects and morphological changes of the use of experimental nanohydroxyapatite gel on microhardness, roughness and color change on tooth hard tissue were examined in vitro.

[0067] In the presence of chitosan, nano-hydroxyapatite can be used in-clinically or by the patient to reduce adverse effects after bleaching treatment, in the form of a paste or gel, integrated into the bleaching agent. In addition, for the treatment of dentin sensitivity, it can be used in restorative dentistry and pedodontics as a preventive or therapeutic method and in dentistry practice.

[0068] Chitosan prevents mineral release from the enamel surface and prevents enamel demineralization. Chitosan also has many useful properties, such as being non-toxic, hydrophilic, biocompatible, biodegradable, and antibacterial, which makes it a versatile material in many biomedical applications. Chitosan works as a thickener and carrier due to its ability to form a thin film.

Claims

CLAIMS1. A nano-hydroxyapatite composition for use after the tooth bleaching process, characterized in that it comprises the following:• 88 wt % of titanium powder,• 2 wt % chitosan.

2. The composition according to Claim 1, characterized in that it further comprises 10 wt % distilled water.

3. The composition according to Claim 1, characterized in that it is in gel form.

4. A production method of the composition according to Claim 2, characterized in that it comprises the following process steps:a. Mixing titanium powder, chitosan and water with a sonic mixer,b. Mixing titanium powder, chitosan and water in a magnetic mixer, c. Drying the solution,d. Incinerating the solution in a high-temperature ashing furnace.

5. The production method of the composition according to Claim 4, characterized in that the mixture is mixed for 15 minutes in the process step a.

6. The production method of the composition according to Claim 4, characterized in that the mixture is mixed for 1 hour in the process step b.

7. The production method of the composition according to Claim 4, characterized in that the solution is dried at 80°C for 24 hours in the process step c.

8. The production method of the composition according to Claim 4, characterized in that the solution is burned at 800°C at a speed of 10°C / min for 30 minutes in the process step d.

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