Development Team
Principal Investigator Prof. Farhan J Ahmad Jamia Hamdard, New Delhi
Paper Coordinator Dr. Javed Ali
Jamia Hamdard, New Delhi
Content Writer Dr. Mohd. Aqil
Jamia Hamdard, New Delhi
Content Reviewer Dr. Sanjula Baboota
Jamia Hamdard, New Delhi
CONTENTS
Anatomy of tooth
Dentifrices
Tooth powder
Tooth paste
Formulation
Basic ingredients
Application of tooth paste/dental care products
Packaging of dental care products
Evaluation of dental care products
Introduction Anatomy of Teeth
The different parts of a tooth are shown in Fig. 1 and described hereunder:
Fig. 1: Parts of a Tooth
Crown: The top part of the tooth and the only part you can normally see. The shape of the crown determines the tooth's function. For example, front teeth are sharp and chisel-shaped for cutting, while molars have flat surfaces for grinding.
Gumline: Where the tooth and the gums meet. Without proper brushing and flossing, plaque and tartar can build up at the gumline, leading to gingivitis and gum disease.
Root: The part of the tooth that is embedded in bone. The root makes up about two-thirds of the tooth and holds the tooth in place.
Enamel: The outermost layer of the tooth. Enamel is the hardest, most mineralized tissue in the body, yet it can be damaged by decay if teeth are not cared for properly.
Dentin: The layer of the tooth under the enamel. If decay is able to progress its way through the enamel, it next attacks the dentin, where millions of tiny tubes lead directly to the dental pulp. It forms the bulk of the tooth and can be sensitive if the protection of the enamel is lost.
Pulp: The soft tissue found in the center of all teeth, where the nerve tissue and blood vessels are. If tooth decay reaches the pulp, you usually feel pain. The pulp extends from the crown to the tip of the root. Each tooth and periodontal ligament has a nerve supply and the teeth are sensitive to a wide variety of stimuli. The blood supply is necessary to maintain the vitality of the tooth.
Cementum: The layer of bone-like tissue covering the root. It is not as hard as enamel.
Structures around the tooth
Periodontal ligament: It is made up of thousands of fibres which fasten the cementum to the bony socket. These fibres lead the tooth to the jaw bone and act as shock absorbers for the tooth which is subjected to heavy forces during chewing.
Oral Mucosa: This is the term used to describe the moist tissue that lines the mouth.
Gums: These are the soft tissues that immediately surround the teeth and bone. It protects the bone and the roots of the teeth and provides an easily lubricated surface.
Bone: It provides a socket to surround and support the roots of the teeth.
Nerves and blood supply: Each tooth and periodontal ligament has a nerve supply and the teeth are sensitive to a wide variety of stimuli. The blood supply is necessary to maintain the vitality of the tooth.
Dentifrices (Dental Products)
Dentifrices are oral health care products that are used by people on a daily basis to promote oral hygiene. They serve as essential vehicles to carry inert and bioactive substances that provide cosmetic and therapeutic benefits. The term dentifrice is derived from dens (tooth) and fricare (to rub).
Dentifrices can be classified as regular cleansing dentifrices or medicated (therapeutic) dentifrices. Regular dentifrices are the preparations used for cleaning and polishing the surfaces of teeth to keep them shiny and to maintain good health of the teeth and gums. These preparations also help inhibit the formation of unpleasant odors and freshen the breath.
Medicated dentifrices are usually cleansing preparations carrying additionally some medicaments which minimize the occurrence of tooth decay or periodontal disease. The active ingredients which are added in these preparations include bactericidal, bacteriostatic, enzyme inhibiting and acid neutralizing agents. Therapeutic dentifrices bearing stannous fluoride are widely used.
There is evidence of the use of various materials for cleaning and shining the teeth in medieval age. Greeks and Romans used materials like dried plant or animal parts, honey, ashes and minerals as dentifrices. Many of these items were found to be harmful, destroying teeth, irritating and damaging oral mucosa. Modern day dentifrices are available mostly in paste, gel and powder forms and less frequently in liquid and stick forms. In some religious groups and cultures, people still practice traditional toothbrushing without dentifrice with, e.g, a miswak or salt.
Toothpaste
Toothpastes are most popular and widely used preparations for cleansing the teeth and possess largest market share amongst all dentifrices. Though they are more expensive than toothpowders yet they are more preferred because of the following reasons:
1. Attractive consistency.
2. Better coverage of dental set up.
3. Easy to take measured quantity on the tooth brush.
4. No spillage and wastage.
Characteristics of Toothpaste
The ideal characteristics of toothpaste include:-
1. It should be non-toxic and non-irritant to teeth, gums and buccal mucosa.
2. It should have very fine particle size and should be free from grittiness.
3. It must clean the dental surface properly without any scratches.
4. It should be easily squeezed out of the tube to spread on the brush without sinking into it.
5. The consistency should remain constant in wide range of temperature during shelf life.
6. It should not dry quickly.
7. It should not interact with the container parts.
Formulation of Toothpaste
The raw materials used for manufacture of toothpaste (Table 1) can be classified as:- I Basic ingredients
1. Abrasives 2. Detergents 3. Humectants 4. Binding agents
5. Sweetening Agents 6. Flavors
7. Preservatives II Special ingredients
1. Coloring agents 2. Bleaching agents 3. Lubricants
4. Therapeutic ingredients
I Basic ingredients 1. Abrasives
Abrasive is the main constituent of all dentifrices. An abrasive is a powder material hard enough to remove the stains without any damage to tooth structures. The abrasive effect is measured in the RDA (Radioactive Dentine Abrasion) scale, ranging from 40- 80 in most toothpaste. Abrasives are usually water insoluble, should not have unpleasant taste, odor and should be non toxic. The main function of abrasives is to remove the food particles lodged in the teeth. They also help remove some stains from the teeth. Usually, the amount of abrasive(s) is about half of total weight of a toothpaste. Commonly used abrasives are calcium carbonate, tricalcium phosphate, dicalcium phosphate, aluminium sulphate, magnesium trisilicate etc. Transparent toothpastes, commonly called gel toothpastes, are prepared by mixing certain abrasives.
Calcium carbonate is the most frequently used abrasive. It is available in different grades. Usually very light grade calcium carbonate is used in toothpaste preparations as it does not harden easily. It also imparts alkalinity to the preparation. Chalk is a native form of raw calcium carbonate.
Other salts of calcium used as abrasives are dihydrate and anhydrous dicalcium phosphate, tricalcium phosphate and calcium pyrophosphate with dicalcium phosphate dihydrate being most commonly used. They are used both as mild abrasives and polishing materials. Dicalcium phosphate is white, odorless and tasteless, slightly soluble in water. Tricalcium phosphate is also tasteless, odourless, white amorphous powder, insoluble in water. It also has mild abrasive and polishing effect. Dicalcium phosphate imparts neutral pH to the paste whereas calcium carbonate gives alkaline pH. Hence, preparations containing calcium phosphates have better taste and enhance the stability of the flavor.
Sodium metaphosphate is water insoluble and has a good abrasive effect and is used along with tricalcium phosphate. It promotes the lustre of teeth. Magnesium trisilicate is a hydrated magnesium silicate and is used with other abrasives and polishing materials. It is white, tasteless and odourless powder, insoluble in water. Aluminium hydroxide also has abrasive and cleansing properties. It is used along with other abrasives and polishing agents.
Other substances like calcium phosphate, talc, kaolin, zirconium silicate etc. are mild abrasives and are seldom used.
2. Detergents
The cleansing action of the detergents (surfactants) is due to their lowering of interfacial tension and production of foam thus helping in wetting and dispersion of powdered materials in the paste. They also help in penetration of paste and abrasives into the fine cracks and other places thus assisting in removal of food particles and debris. By their emulsification capability they help in removal of mucus. The amount of detergents added in the toothpaste varies from 1 to 3%.
Synthetic detergents are widely used surfactants in toothpastes. Sodium lauryl sulfate is one of the most commonly used detergents. Others are magnesium lauryl sulfate, sodium lauryl sarcosinate, diethyl sodium lauryl sarcosinate. Detergents may lower the abrasive effect of toothpastes.
Though soaps are alkaline in nature but they are still used in preparation of toothpastes.
As soaps may have odor or taste, odorless and tasteless soaps are preferred.
3. Humectants
The humectants help retain moisture and prevent drying out of the toothpaste and thus impart plasticity to the product. They prevent loss of water, and subsequent hardening of the paste, when it is exposed to air. The amount of humectants used in toothpaste can vary from 20% to 35%. The actual amount depends on the specific gravity of the powder mix. Less amount of humectant is used in substances with lower specific gravity. Commonly used humectants in toothpaste are glycerin, sorbitol and propylene glycol. Of these, glycerin is most widely used. It also imparts some sweetness.
Sometimes sorbitol is preferred as it imparts more viscosity and plasticity than glycerin.
4. Binding agents
Binding agents are used in toothpaste to control viscosity and maintain creamy consistency. They also prevent separation of toothpaste. Various hydrocolloids are used for this purpose usually in concentration of 1-2%. Previously, starch, liquid glucose and simple syrup were used; they have been gradually substituted by mucilages of karaya gum, tragacanth and gum arabic. Gum tragacanth is one of the most widely used binders. The amount of binding agent can be selected depending upon the consistency desired. The gum is first mixed with sufficient quantity of glycerin and alcohol before adding water to prevent formation of lump.
Other substances used as binding agents are mucilages of carboxy methyl cellulose sodium alginate, carbopol, bentonite, veegum etc.
5. Sweetening Agents
Sweetening agents are used in the toothpaste to improve the taste of the preparation in the mouth. Saccharine sodium is the most commonly used sweetener. They are usually used in concentration of 0.05-2%. The exact amount is determined by the quantity and sweetness of other ingredients present like glycerin.
6. Flavors
Flavoring agents are essentially used in toothpaste for fragrance and good feel during the usage of the product. The flavors used in toothpaste are blending of volatile oils which produce a pleasant and refreshing smell in the mouth after use. In combination with sweetening agents, they contribute to the distinct paste of the product. Examples of commonly used flavors are peppermint oil, spearmint oil clove oil cassia oil, cinnamon oil, menthol etc.
7. Preservatives
Preservatives are essentially added in toothpaste to prevent microbial growth due to presence of gum and water. Sweetening agents like glycerin and flavors may add to antimicrobial action of the preservatives. Commonly used preservatives in toothpaste are methyl para hydroxybenzoate (0.15%) and propyl para hydroxybenzoate (0.02%).
8. Solvent
Water is the most common solvent used in toothpastes in concentration of 20-40%.
II Special ingredients
There are various other additives which are used in toothpaste in order to achieve certain special functions as follows:
1. Coloring agents: Colors are not usually added in the toothpastes as most of these are white. Though these days colored toothpastes are available in the market to mask the color of other ingredients or to catch the attention of the consumer. The colors to be added in the toothpaste must be selected from the approved list of coloring agents under Drugs and Cosmetics Act and Rules. Pink red and green are commonly used colors in toothpastes. Multi colored and striped toothpastes are also prepared using combinations of different colors 2. Bleaching agents
Bleaches are added in toothpastes for removal of stains and whitening of the teeth. They are basically oxidizing agents such as hydrogen peroxide, magenesium peroxide and sodium perborate.
3. Lubricants
Lubricants facilitate the easy removal of the paste from the tube or container without any extra pressure. Liquid paraffin (1-2%) can be used as a lubricant.
4. Therapeutic ingredients
Active ingredients are added in the toothpaste as desired for specific functions.
For removal of calculus or tartar, pyrophosphates, zinc and pancreatin (approx.
2%) have been used without any damage to tooth enamel. Dimethicones, hydrogen peroxide and papain have been used as whitening agents.
It has been reported that fluoride toothpastes reduce caries in the deciduous dentition by 37% and by 24% in the permanent dentition of children and adolescents. A meta-analysis also concluded that fluoride is effective in preventing caries in adults of all ages. The most important anti-caries effect is claimed to be due to the formation of calcium fluoride (CaF2) in plaque and on the enamel surface during and after rinsing or brushing with fluoride. The
effectiveness of fluoride toothpastes are concentration dependent. The fluoride content in toothpaste is usually between 0.10-0.15%. Brushing with fluoride toothpaste may be recommended twice daily. Fluorides such as stannous fluoride, amine fluoride, sodium fluoride and sodium monofluorophosphate have been widely used in medicated toothpastes to prevent tooth decay.
Stannous fluoride combines with tooth enamel and forms tin oxide, tin phosphates and calcium fluoride which inhibit acid penetration and tooth decay.
Other anti caries agents used in toothpastes are xylitol and sodium carbonate.
Strontium chloride is added in toothpastes for treatment of hypersensitivity.
Sodium lauryl sarcosinate is also used in tooth pastes for anti-enzyme, bacteriostatic and anticariogenic activities in addition to its usual foaming action. Alkalis and urea are added to neutralize acid in saliva and to prevent decomposition of carbohydrates and formation of acid. Examples of antiplaque agents used in toothpastes are sodium lauryl sulfate, triclosan, metal ions like stannous and zinc, essential oils and chlorhexidine. Zinc and chlorophyll have been used as anti-halitosis agents to prevent bad odor in mouth.
Table 1: Raw materials used in toothpastes
Ingredient Quantity
Abrasive 20 – 50 %
Detergent 1 - 3 %
Humectant 20 - 35 %
Binder 1 - 2 %
Sweetener 0.05 - 2 %
Flavor 0 - 2 %
Therapeutic agent 0 - 2 %
Water 20 - 40 %
Color or preservative 0.05 – 0.5 %
of toothpastes
Formulae of some toothpastes are given below:-
Formula 1
Ingredients %w/w Calcium carbonate 56.0 Sodium lauryl sulfate 1.0
Gum Tragacanth 1.5
Glycerin 22.0
Saccharine sodium 0.1
Water 19.4
Flavor q.s.
Preservative q.s.
Formula 2
Ingredients %w/w Calcium pyrophosphate 40.0
Glycerin 29.0
Gum Tragacanth 1.0
Stannous fluoride 0.4 Stannous pyrophosphate 1.0 Sodium lauryl sulfate 1.5
Saccharine Sodium 0.1
Water q.s.
Flavor q.s.
Preservative q.s.
Formula 3
Dicalcium phosphate 60.0
Sorbitol 16.0 Sodium lauryl sulfate 1.0
Gum Tragacanth 1.0
Saccharine sodium 0.1
Water 21.9
Preservative q.s.
Flavour q.s.
Procedures for preparation of toothpastes
Toothpastes can be made in stainless steel mixer or planetary mixer or any other mixer used for used for making semisolid preparations. General methods for preparing toothpastes are given below:-
Method A:
1. Mix the gum with a suitable quantity of humectant without any water.
2. Other colloids like methyl cellulose may be dispersed with cold water. Ethyl cellulose should be mixed in warm water.
3. Pass the other powder ingredients through a suitable sieve and add gradually to the above binder mixture with continuous stirring. Then add the above mixture to the aqueous medium.
4. Finally add the flavor and detergent and stir further to obtain the final product.
Method B:-
1. Mix the binder with abrasives and other powders.
2. Add the above mixture in a suitable mixer along with aqueous solution of the humectant, preservative and sweetening agent.
3. Continue the mixing to obtain a homogenous mixture.
4. Finally add flavor and detergent.
Tooth Powder
Tooth powders are one of the oldest, simplest and the cheapest dental preparations. Their market share has been reduced over the years due to popularity of toothpastes but they are still being used by a sizeable population. The main disadvantages of tooth powder are:-
1. Floating of powders in air during preparation and use.
2. Formation of cake on storage.
3. Uneven distribution in mouth.
Formulation (Basic ingredients) of toothpowder
The basic ingredients used in tooth powder are the same except that the binders, humectants and solvent are not required. Abrasives used in tooth powders are also same as in tooth pastes like calcium carbonates, calcium phosphates, tricalcium phosphates, calcium sulphonates etc.
Heavy grade calcium carbonate is used in tooth powders whereas lighter grade is used in tooth pastes.
Below are typical formulae of tooth powders:
Formula 1
Ingredients %w/w
Calcium carbonate 84.0 Tricalcium phosphate 10.0 Sodium lauryl sulfate 3.0
Sodium perborate 2.0
Saccharine sodium 1.0
Color q.s
Flavor q.s.
Formula 2
Ingredients %w/w Calcium carbonate 92.8 Dental soap powder 6.0
Saccharine sodium 0.2
Flavor q.s.
Procedure for preparation of toothpowder
A general procedure for manufacture of toothpowder is given hereunder:
1. Mix all the ingredients in ascending order of their weights in a ribbon type or agitator type mixture.
2. Finally spray the favouring agent on the top of the above powder mix and stir well.
Application of toothpastes/dental care products
The toothpastes and other dental care products are used for the following purposes:
1. Dentifrices are primarily used for cleansing of teeth.
2. They are also used for polishing and whitening of the teeth.
3. They prevent halitosis (bad odour) and refresh the breath.
4. They improve remineralisation of teeth.
5. They reduce hypersensitivity of teeth.
6. They inhibit formation of calculus or tartar.
7. They prevent and remove dental plaque.
8. They prevent caries and tooth decay.
9. They are recommended for prevention of periodontal disease.
10. They are claimed to be effective in correction of xerostomia and mouth ulcer.
Safety of dentifrices
While dentifrice products have been considered to be safe over the years, concerns have been raised for dental fluorosis due to fluoride ingestion in children under the age of six years. There are reports that for children 1–3 years, 30–75% of the dentifrice is ingested, and for children 4- 7 years 14–48% is swallowed. Hence, precautions need to be taken to prevent overdose. The FDA requires labeling of all fluoride containing dentifrices to include a statement "to minimize swallowing use a pea-size amount in children under six." It is also recommended to make childproof caps on fluoride dentifrice products meant for use by children. Alternatively, metered dentifrice delivery systems can be presented for children less than six years, for dispensing of the correct amount of fluoride depending on the body weight of the child.
Dentifrices containing fluorides in concentrations >1500 ppm are categorized as prescription only medicines (POM) and should be used only above the age of 10 years and for the management of high caries risk individuals such as those with xerostomia or root surface caries.
Sodium lauryl sulfate, commonly used surfactant in toothpastes may occasionally cause mucosal desquamation or ulceration. Triclosan can react with water to produce chloroform which, if ingested in large quantities, can cause depression, liver problems and, in some cases, cancer. Essential oils, flavors, cinnamonaldehyde, benzoates, carvone and antimicrobial agents,
can cause irritation or allergic reactions in the mouth, lips as contact cheilitis and circumoral dermatitis. Occasionally, allergic rhinitis or asthma may occur.
Packaging of dental care products
The toothpastes are commonly packed in collapsible tubes. The toothpaste tube has three main layers: an inner layer of polyethylene plastic, a metallic foil layer to prevent flavor loss and an outer layer of thermo plastic material that can be printed on. The disk or “shoulder” near the cap is also made from polyethylene. The cap is made from polypropylene plastic and can be designed also to be flipped open (not just unscrewed). All toothpaste boxes contain recycled material and are recyclable. Box ends are tightly closed so that they are tamper resistant.
Colgate began manufacturing toothpaste in “pumps” in 1984. The body and head of the pump is made from polypropylene with some smaller components made from low density polyethylene.
Toothpowders are usually packed in wide mouth plastic containers.
Evaluation of dental care products
The dental preparations can be evaluated for their quality by analyzing the following characteristics:
1. Abrasiveness
Abrasiveness can be tested by rubbing the toothpastes or toothpowders on extracted dental set and then observing the abrasive function visually or mechanically.
2. Particle size
It can be estimated microscopically or by sieving. The particle size should be ideal in order to provide good abrasiveness without any gritty feel and to minimize damage to the gums.
3. Consistency
The viscosity of the paste and rheology of the powders should be optimum to ensure smooth flow of product from the container.
4. Cleansing action
This can be assessed by brushing the teeth for 2 weeks with the toothpaste/powder and then examining the appearance of the teeth before and after use by comparing the photographs. Alternatively it can be assessed by observing the change in the reflectance of a lacquer coating on a polyster film caused by brushing with a toothpaste/powder.
5. pH of the product
A 10% dispersion of the product is made in water and pH is determined. It should be optimum so as not to damage the teeth and the gums.
6. Foaming property
This test is essential for evaluation of foam producing dentifrices. A fixed amount of the product is mixed in sufficient quantity of water and stirred vigorously. The foam generated is then observed for its nature, density, stability and washability.
7. Volatile matter and moisture
A predetermined quantity of the product is taken in a dish and is dried till a constant weight is obtained. Change in weight will indicate the percentage of moisture and volatile matter.
8. Limit test for heavy metals
The dental products are also tested for the content of arsenic and lead as these are very toxic metals and can harm the user if found in excess quantity.
9. Effect of special ingredients
Specific tests may be performed for evaluation of special ingredients in dental products like antienzyme action of sodium lauryl sarcosinate and anticariogenic action of fluorides.
SUMMARY
Dentifrices are oral health care products that are used by people on a daily basis to promote oral hygiene. They make the teeth appear shiny and attractive. They are also used for prevention of caries, tooth decay, plaque, tartar (calculus), hypersensitivity, bad odour, and periodontal diseases. Dentifrices are available in paste, powder, gel and stick forms. The basic ingredients of a tooth paste include abrasives, surfactants, humectants, binding agents, sweetening agents, flavors and preservatives. In tooth powders binders and hemectants are not required. Abrasive is the most commonly used ingredient in dentifrices used for cleansing action and usually comprises about 50% or more of the product. Some special ingredients are added in the dental products as desired. These include coloring agents, bleaching agents, lubricants etc. Bioactive substances like anticaries agents e.g. stannous fluoride, amine fluoride, sodium fluoride, sodium monofluorophosphate, xylitol and sodium carbonate are used to prevent tooth decay. For removal of calculus or tartar, pyrophosphates, zinc and pancreatin are added. Dimethicones, hydrogen peroxide, and papain have been used as whitening agents.
Strontium chloride is added in toothpastes for treatment of hypersensitivity. Examples of antiplaque agents used in toothpastes are sodium lauryl sulfate, triclosan, metal ions like stannous and zinc, essential oils and chlorhexidine. Zinc and chlorophyll have been used to prevent bad odor in the mouth. The dental preparations can be evaluated for their quality by analyzing characteristics like abrasiveness, particle size, consistency, cleansing action, pH, foaming, volatile matter and moisture, limit test for heavy metals and effect of special ingredients. Dentifrices should be used with caution by children under six years of age as they have been reported to cause dental fluorosis.
