Patent Publication Number: US-10765499-B2

Title: Method of bleaching teeth

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/449,186, filed Aug. 1, 2014, the entirety of which is incorporated herein by reference. 
    
    
     FIELD 
     The present method relates to the field of dental whitening and in particular to methods of use of dental bleaching compositions. 
     BACKGROUND 
     Stained or discolored teeth are considered as a cosmetic impairment. Teeth&#39;s whitening is a cosmetic treatment done to improve the appearance of teeth. Teeth are whitened to remove impairments such as those resulting from the effects of coffee, cigarettes, and other substances that permanently stain or discolor teeth. Different techniques of teeth whitening or bleaching are known and relatively simple procedures improving the stained teeth appearance exist. The procedures can be conducted in a dental clinic, office or in a residential environment. 
     A variety of dental bleaching compositions and dental bleaching devices or trays exist on the market. Such dental bleaching compositions are typically applied to a person&#39;s teeth using a dental tray configured so as to retain the dental composition against the person&#39;s teeth. Treatment time can vary between about 10 minutes to a few hours and although conducted in a residential environment it can temporarily limit the user&#39;s freedom of speech, movement and function during the treatment period. In addition, it is uncomfortable for the user to keep a dental tray in the mouth over relatively long periods of time. User comfort during the teeth bleaching treatment duration may be improved by shortening the time of bleaching. 
     Most common bleaching agents used are peroxides, including but not limited to hydrogen peroxide, carbamide peroxide, sodium perborate, and sodium percarbonate. The simplest way to shorten the treatment time can be to increase the concentration of the peroxide. However, use of higher concentrations of bleaching agents (e.g., peroxides) can result in irritation and even some damage of oral mucosa such as gums or lips or other soft tissue. 
     As a result, the current methods of application of bleaching agents disclose using lower concentrations of bleaching agents, applying protection to the gums such as a protective light curable gingival protector or similar prior to application of the bleaching agent or using bleaching agents other than hydrogen peroxide such as chlorine dioxide and oxy-chlorine anions (U.S. Pat. No. 8,377,423). 
     Another way to accelerate bleaching time and speed up the chemical reaction related to the bleaching process can be concurrent application of heat or light or DC (Direct Current) electric current to the bleaching composition as disclosed in U.S. Pat. No. 7,775,795. 
     SUMMARY 
     Presented is a method of safe application of a dental bleaching agent, mainly hydrogen peroxide to teeth to speed up and shorten a teeth whitening treatment session while maintaining the safety of the treatment. The method can include applying initially a first dental whitening composition having a high concentration of a bleaching agent (e.g., hydrogen peroxide) to the teeth followed by applying a second dental whitening composition having a low concentration of a bleaching agent. 
     The method can also include generating DC electrical current through the mixture of the applied dental whitening compositions so that to accelerate the activity of the bleaching agent and further shorten the teeth whitening treatment time. 
     The first dental whitening composition having a high concentration of the bleaching agent and the second dental whitening composition having a low concentration of a bleaching agent can be applied consecutively and/or concurrently during the same teeth whitening treatment session. 
     The method also includes applying the first dental whitening composition having a high concentration of the bleaching agent and the second dental whitening composition having a low concentration of a bleaching agent together and allowing sufficient time so that the bleaching agent concentration within the mixture of the compositions stabilizes by diffusion at a concentration sufficiently high to whiten the teeth but not cause any irritation to the oral mucosa. 
     The first composition is operative to penetrate deep within the enamel wherein the high concentration of the hydrogen peroxide in the first composition operates to erase most of embedded stains. Applying the second composition to the same stains for a same period of time would not affect the embedded stains affected by the first composition. Hence, the first composition penetrates deep within the enamel to erase most of embedded stains not affectable by the second composition when applied for a same period of time. 
     The bleaching agent (e.g., hydrogen peroxide) can be an ingredient in, for example, a whitening gel being, for example, a composition of one or more ingredients including hydrogen peroxide as a bleaching agent, a cross-linked polyacrylate polymer as a thickening component, and the electrical conductivity enhancing ingredients such as electrolytes. Potassium nitrate and/or potassium hydroxide are examples of such electrolytes. Each of them could be included alone in the composition or a mix of both of them could be used to enhance conductivity of the dental bleaching gel composition. 
     Other ingredients can include Glycerin, propylene glycol and water are used as vehicles and solvents in which other ingredients or components are mixed to prepare the dental bleaching gel composition. 
     Other ingredients affecting antimicrobial and oxidizing properties of the gel, mouth refreshing components and components improving bleaching gel viscosity and wetting properties are added as required to the composition. 
     The concentration of bleaching agent in the composition can vary (i.e., lower) over time so that to drop below a concentration level that can irritate the oral mucosa. 
     Applying the dental whitening composition or gel could be done by placing the composition or gel in a dental cosmetic treatment tray or applicator configured to retain the dental composition against the person&#39;s dental arcade, such as the Pearl®. applicator commercially available from Illuminage Beauty LTD, Yokneam Industrial Zone, 2069201 ISRAEL). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a frontal view simplified illustration of an example of a first step of a safe method for cosmetic whitening of teeth; 
         FIG. 2  a frontal view simplified illustration of a second step of an example of a safe method for cosmetic whitening of teeth; and 
         FIG. 3  a frontal view simplified illustration of yet another step of an example of a safe method for cosmetic whitening of teeth. 
     
    
    
     DESCRIPTION 
     In the context of the present disclosure the terms “dental bleaching” and “dental whitening” have the same meaning. 
     DC electric current is known to accelerate the bleaching reaction. The DC electric current activates the bleaching agent and accelerates the bleaching reaction. The DC current activates certain ingredients of a specially formulated whitening gel, allowing it to penetrate deep within the enamel to erase most of embedded stains without sensitivity or irritation. Use of DC electrical current and specially formulated gel has proved to deliver whitening results much better than light or heat activated teeth whitening treatments. 
     The term “dental whitening composition having a high concentration of hydrogen peroxide” and “the first composition” mean the same and refer to a dental whitening bleaching agent composition having a concentration of hydrogen peroxide between 20% and 50% (w/v). 
     The term “dental whitening composition having a low concentration of hydrogen peroxide” and “the second composition” mean the same and refer to a dental whitening bleaching agent composition having a concentration of hydrogen peroxide between 0.1%-15% (w/v). 
     As described above, applying bleaching agents such as hydrogen peroxide to teeth could be harmful to the oral mucosa and other adjacent soft tissue. However the effect of a bleaching agent such as hydrogen peroxide on tissue depends not only on the concentration of the bleaching agent in the applied bleaching composition but also on the length of contact time (i.e., direct contact) of the bleaching agent with the tissue. 
     Application of higher concentrations of hydrogen peroxide, e.g., concentrations between 20% and 50% (w/v) can be highly effective whitening or bleaching teeth however, contact time must be short in order to avoid irritation to oral mucosa and other soft tissue. 
     On the other hand, a low concentration of hydrogen peroxide, e.g., concentrations of 0.1%-15% (w/v) can be safer to oral mucosa and other adjacent soft tissue but can require and extended contact time to be effective and whiten teeth satisfactorily. Another aspect of treatment with hydrogen peroxide is that the longer the contact time of hydrogen peroxide, even at lower concentrations, the higher the risk of afflicting irritation to the oral mucosa and adjacent soft tissue. 
     The below described method combines a first dental whitening composition having a high concentration (20% and 50% (w/v)) and a second dental whitening composition having a low concentration (0.1%-15% (w/v)) of a bleaching agent applied for a longer duration and allowing sufficient application time of the mixture so that over time the bleaching agent concentration within the mixture of the compositions in contact with the teeth and oral mucosa stabilizes by diffusion at a concentration sufficiently high to whiten the teeth but not cause any irritation to the oral mucosa and adjacent soft tissue. In other words, the concentration of the bleaching agent in the whitening composition in contact with the teeth and oral mucosa is different and can vary (i.e., become lower) over time by diffusion so that to drop below a concentration that can irritate the oral mucosa. 
     The first dental whitening composition is operative to penetrate deep within the enamel wherein the high concentration of the hydrogen peroxide in the first dental whitening composition operates to erase most of embedded stains. Applying the second dental whitening composition to the same stains for a same period of time would not affect the embedded stains affected by the first dental whitening composition. Hence, the first composition penetrates deep within the enamel to erase most of embedded stains not affectable by the second composition when applied for a same period of time. 
     Applying the first dental whitening composition or gel could be done by means of an applicator or brush  102  ( FIG. 1 ). Applying the second dental whitening composition or gel to the teeth can be done by placing the second dental whitening composition in a cosmetic treatment tray or applicator  202  ( FIG. 2 ) configured so as to retain the dental composition against the person&#39;s dental arcade  100  ( FIG. 1 ). The tray or applicator could be such as the Pearl® applicator commercially available from Iluminage Beauty LTD, Yokneam Industrial Zone, ISRAEL and depicted in  FIG. 2  by phantom lines. 
     The method includes applying a thin film of a first composition ( FIG. 1 ) having a high concentration of a bleaching agent for a very short duration immediately followed by applying a second composition ( FIG. 2 ) including a low, safe concentration of a bleaching agent without irritation of the oral mucosa and other adjacent soft tissue and allowing sufficient time so that the bleaching agent concentration within the mixture of the compositions stabilizes by diffusion at a concentration sufficiently high to whiten the teeth but not cause any irritation to the oral mucosa. 
     Additionally and optionally, the bleaching gel could also include one or more electrical conductivity enhancing ingredients such as electrolytes. When using a bleaching gel including electrical conductivity enhancing ingredients, the method of application could include applying a thin film of a first dental bleaching gel ( FIG. 1 ) producing a high concentration of hydrogen peroxide (i.e., 20% and 50%) immediately followed by applying to the treated teeth an applicator  202  ( FIG. 2 ) including a second dental bleaching gel (not shown) producing a low concentration of hydrogen peroxide (i.e., 0.1% and 15%) and activating applicator  202  by pressing on an ON/OFF button  304  ( FIG. 3 ) and applying a DC current through the mixture of compositions retained in the applicator and in contact with the teeth so that to accelerate the bleaching activity of the hydrogen peroxide on teeth and shorten the teeth bleaching treatment time. 
     The first dental whitening composition having a high concentration of the bleaching agent and the second dental whitening composition having a low concentration of a bleaching agent can be applied consecutively and/or concurrently during the same teeth whitening treatment session. 
     The bleaching agent can be an ingredient in, for example, a whitening gel being, for example, a composition of one or more ingredients including hydrogen peroxide as a bleaching agent, a cross-linked polyacrylate polymer as a thickening component, and the electrical conductivity enhancing ingredients such as electrolytes. Potassium nitrate and/or potassium hydroxide are examples of such electrolytes. Each of them could be included alone in the composition or a mix of both of them could be used to enhance conductivity of the dental bleaching gel composition. 
     Other ingredients can include Glycerin, propylene glycol and water are used as vehicles and solvents in which other ingredients or components are mixed to prepare the dental bleaching gel composition. 
     Other ingredients affecting antimicrobial and oxidizing properties of the gel, mouth refreshing components and components improving bleaching gel viscosity and wetting properties are added as required to the composition. 
     It will be appreciated by persons skilled in the art that the present methods are not limited to what has been particularly shown and described hereinabove. Rather, the scope of the methods includes both combinations and sub-combinations of various features described hereinabove as well as modifications and variations thereof which would occur to a person skilled in the art upon reading the foregoing description and which are not in the prior art.