Dental Pharmacology Notes

Fluorides

Fluoride is a mineral that is present naturally in food and water. It is absorbed mainly in the intestine. It is widely distributed in the body but gets concentrated in teeth and bones. The kidney is the major route of excretion.

Actions On Teeth

• Teeth are composed mainly of calcium hydroxyapatite. Fluoride exchanges with hydroxyl ions to form calcium fluorapatite, which is more stable in acid than calcium hydroxyapatite.
• Calcium fluorapatite makes the outer layers of the enamel harder so that the teeth are resistant to acid attack. Fluoride prevents the decalcification of enamel by acids and prevents caries.
• The free fluoride ions released from calcium fluorapatite by the action of acid promote remineralization of enamel, which had been previously demineralized. Fluoride gets concentrated in plaque and inhibits microbial enzymes required for acid production.

Read And Learn More: Pharmacology for Dentistry Notes

Use Of Fluorides

• Dental caries: Caries is a degenerative condition characterized by disintegration of teeth starting from the periphery in the enamel and gradually extending to the pulp/soft tissues.
• Microorganisms present in the oral cavity act upon residual carbohydrates to produce acids. Acids attack the teeth leading to demineralization of enamel and finally cavitation.
• There is an increased incidence of dental caries in areas where drinking water is deficient in fluorides. Fluoridation of drinking water or common salt can be done in these areas.
• Sodium fluoride can be supplemented as tablets, toothpaste, gel and foam, varnish, and mouthwash. There are various ways of using fluorides – community-based, professional application, and individual use.

Community-Based Methods

1. Fluoridation of drinking water
   • Fluoridated drinking water has an optimal concentration of fluoride and is effective in preventing caries in children and adults. The optimal level of fluoride in drinking water is 1 ppm. This optimal level occurs either naturally or is obtained by the addition of fluoride to the community water supply (sodium fluoride is used).
2. Salt fluoridation
   • It is an alternative to water fluoridation which has been implemented in a few countries, wherein 200–300 mg of sodium fluoride/kg salt is added.

Topical Use Of Fluorides

1. Fluoridated toothpaste
   • On brushing, fluoride in toothpaste is taken up by plaque and demineralized enamel. Its concentration is also transiently increased in saliva from where it is taken up by the plaque. Sodium monofluorophosphate is the commonly used fluoride salt in toothpaste.
   • Sodium fluoride may be used but gets inactivated by calcium salts (abrasives) used in toothpaste. Stannous fluoride is not preferred now, as it stains the teeth. People using fluoridated toothpaste should be advised to rinse the mouth well after brushing.
2. Fluoride mouth rinse
   • The fluoride of mouthrinse is retained in the plaque and saliva and helps prevent dental caries. Sodium fluoride 0.20% solution (920 ppm fluoride) and stannous fluoride 0.63% solution is available. Stannous fluoride can stain the teeth.
   • They can be used daily or weekly, as prescribed by the dentist. Mouthrinse should not be swallowed. To maximize the benefit, the patient should be advised not to eat, drink or rinse the mouth for at least 30 min after using a mouth rinse.

Professional Application Of Topical Fluoride

• It involves topical application of high concentrations of fluoride-containing preparations by dentists.
• Gel or solution of acidulated phosphate fluoride (APF, 1.23%), varnish (2%) of sodium fluoride, is available. A duration of 4 min is required for the application of APF. It is to be applied with a disposable applicator in the upright position.
• Care should be taken not to swallow the preparation. The gums and teeth need to wiped dry after application. It should be repeated at 3- to 6-month intervals.
• There is an increase in the concentration of fluorides in the oral cavity for a brief period. This results in inhibition of demineralization and promotion of remineralization. The acidic medium facilitates entry of fluoride into the enamel.

Fluoride Toxicity

1. Acute fluoride toxicity
   • It occurs due to accidental ingestion of fluoride-containing insecticides. It manifests as nausea, vomiting, abdominal pain, diarrhea, hypotension, hypocalcemia, etc.
   • Gastric lavage is done with calcium gluconate to precipitate fluorides. Intravenous glucose is also administered and acidosis is corrected.
2. Chronic fluoride toxicity
   • Chronic fluoride toxicity, resulting in dental fluorosis, occurs where drinking water has a large amount of fluorides (>2 ppm). In mild cases, a white opaque spot is seen on theteeth. In severe cases, brown pits are seen on the teeth, giving the teeth an irregular appearance. Skeletal fluorosis may be seen when fluoride is more than 8 ppm of drinking water.
   • Fluorosis is a preventable condition by changing the source of water. The progression of the disease can be halted but not reversed.

Astringents

Agents that react with and precipitate proteins in superficial cells to form a protective covering on the surface are called astringents. This cover over the underlying tissue:

1. Protects against bacteria and irritants.
2. Decreases exudation.
3. Arrests capillary oozing when applied to bleeding surfaces.

Types Of Astringents

1. Vegetable astringents
2. Metallic astringents
3. Others: Alcohol (not used as an astringent in oral cavity)

 

1. Vegetable astringents
   • Tannic acid: It is a light-brown powder soluble in glycerine and alcohol.
   • Catechu: Its astringent action is due to the presence of tannic acid.
2. Metallic astringents
   • Aluminum salts: For example, alum and aluminum acetate. Alum is aluminum potassium sulfate or aluminium ammonium sulfate.
     • It can be used as a solution or powder. As it is acidic, it may damage the enamel. Aluminum acetate is less irritating.
   • Zinc salts: For example, zinc chloride, zinc sulfate and zinc oxide. They have astringent and antiseptic properties.
     • They do not stain the teeth. Zinc sulfate is less irritating to the oral mucosa than zinc chloride. The astringent action of zinc oxide is weaker as compared to other zinc salts.
   • Ferric chloride: Its use as an astringent has declined, as it can stain the teeth and damage the enamel.
   • Silver nitrate and copper sulfate: They stain the teeth.

Uses Of Astringents

As a mouthwash, paint, dentifrices, mummifying agent, obtundents, and styptics in gingivitis, aphthous ulcers, bleeding gums, and halitosis.

Desensitizing Agents

• Dentinal hypersensitivity is a sharp, short-lasting dental pain usually provoked by thermal, chemical, tactile, or osmotic stimulation of exposed dentinal tubules.
• Causative factors are lack of oral hygiene, the faulty technique of brushing, acids, recession of gingiva, etc.
• This results in either stimulation of nerve endings in the dentine or changes in the direction of fluid movement within the dentinal tubules, which is perceived as pain.
• An ideal desensitizing agent should be rapid-acting, have a long duration of action, be nonirritant, easy to apply, and should not stain the teeth. Dentinal hypersensitivity is treated by:

1. Desensitizing the nerve: By blocking the transmission of neural signals by topical application of potassium nitrate, e.g. 3% potassium nitrate mouthrinse or 5% potassium nitrate toothpaste.
   • The exact mechanism of action is not clear. There is an increase in extracellular potassium levels in the dentine cavities, which blocks the generation of action potential in the pulpal nerves.
2. Occluding the dentinal tubules
   • Salts: Stannous fluoride, sodium fluoride, potassium oxalate, strontium chloride, potassium nitrate, etc. Fluorides, oxalates, and chloride-containing compounds help to seal the surface of the dentine, decrease the movement of fluid in the tubules, and diminish dentine hypersensitivity.
     • Application of sodium and stannous fluoride results in the precipitation of calcium fluoride crystals, which act as a barrier in the dentinal tubules. But the calcium fluoride formed dissolves in saliva; hence, it has a transient action.
     • However, on long-term use, the fluorides enhance dentine formation and reduce dentine sensitivity. Potassium oxalate reacts with calcium in the dentine to form calcium oxalate on the surface of the dentine and inside the tubules.
     • The drawback of this preparation is that the calcium oxalate formed on the surface is lost following regular brushing of the teeth. Strontium chloride precipitates proteins in the dentinal tubular fluid and occludes the tubules. It also hastens the calcification of the bony components of the tooth.
     • Potassium nitrate is an ingredient of desensitizing toothpastes. It occludes dentinal tubules and reduces pain.
   • Agents that precipitate proteins: Glutaraldehyde, formaldehyde, zinc chloride, silver nitrate, etc. by precipitating proteins, they occlude the tubules and decrease the movement of fluid. Use of silver nitrate can result in a blackening of tooth surface. Formaldehyde has a bad odor and taste, hence is not used now.
   • Resins and dental adhesives: Hydroxyethyl methacrylate and some varnishes seal the open dentine tubules and diminish sensitivity.

Desensitizing agents are available as gel, dentifrices, and mouthwash, or they can be applied topically as varnish, adhesives, resin, glass ionomer composite, etc. Depending on the agent, they can be applied either by the patient (‘at home’) or the dentist (‘professionally applied’).

Uses: Desensitizing agents are used to treat dentinal hypersensitivity due to gingival recession, abrasion and erosion of tooth surface. They can also be used to decrease sensitivity after periodontal treatment. Potassium nitrate can be used before and during tooth bleaching to reduce dentine sensitivity.

Anticaries Agents

• Dental caries is common in children and young adults but can occur in any age group.
• There are various ways of controlling dental caries. Primary preventive measures for controlling caries include use of fluorides, pit and fissure sealants, and dietary modification.

Fluorides

• Fluorides are effective anticaries agents, and their use has reduced the incidence of dental caries. Fluoride inhibits demineralization and promotes remineralization of the enamel.
• It improves the structure of enamel – makes it more acid resistant. It also has antimicrobial actions – thereby inhibiting the fermentation of carbohydrates and acid production.
• Fluorides are administered in the form of fluoridated drinking water, dentifrice, mouth rinse, gel, foam, varnish, and supplements.

Nonfluoride Agents

• Certain non-fluoride agents may provide some benefit as an adjunct to primary prevention measures in children and adults at high risk of developing caries.
• Chewing of sucrose-free polyol gum (containing either xylitol only or polyol combinations) for 10–20 min after meals can be used in children (>5 years) and adults at high risk of developing caries. Xylitol has antimicrobial effects and inhibits acid production in the oral cavity.
• A 1:1 mixture of chlorhexidine/thymol varnish may be efficacious in the prevention of root caries in adults and the elderly.
• Calcium and phosphate in toothpaste or mouth rinse will increase the concentration of these ions in the oral cavity and improve remineralization. Triclosan has antimicrobial and anti-inflammatory effects. Chlorhexidine has broad-spectrum antimicrobial effects.
• But there is not sufficient evidence that non-fluoride agents like calcium and/or phosphate agents (with or without casein derivatives), topical chlorhexidine alone, and triclosan can reduce the incidence of caries.

Prevention Of Caries

• The public, especially children should be educated about good oral hygiene, proper use of toothbrushes, dental floss, etc. Brushing of teeth should be done twice daily.
• Carbohydrate-containing foods like ice cream, chocolates, etc. should be avoided.

Antiplaque Agents

• Dental plaque consists of a wide range of bacteria in a matrix of food debris, bacterial polysaccharides and salivary proteins. Plaque plays an important role in the initiation of caries and can cause gingival inflammation, which can progress to periodontal disease.
• A good antiplaque agent should have prolonged retention time on the oral surface and broad spectrum of antibacterial action with minimal side effects.

The following agents are used as mouthwash or dentifrice for their antiplaque actions.

1. Fluorides: Stannous fluoride, sodium fluoride, organic amine fluoride
2. Bis-biguanides: Chlorhexidine, bis-pyridine
3. Quaternary ammonium compounds: Benzalkonium chloride, cetylpyridinium chloride
4. Phenols and essential oils: Triclosan, thymol, eucalyptol, menthol
5. Enzymes: Amyloglucosidase, glucose oxidase, protease, lipase
6. Antiseptics: Povidone-iodine, chloramine
7. Alkaloids: Sanguinarine
8. Detergent: Sodium lauryl sulfate
9. Metals: Zinc, tin
10. Antimicrobials: Penicillin, tetracycline, gramicidin

Some of the commonly used agents are discussed below.

Fluorides

• Stannous fluoride is more effective than sodium fluoride as an antiplaque agent.
• Stannous fluoride reduces Streptococcus mutans and Streptococcus sanguis in plaque and S. mutans in saliva. Stannous fluoride-treated enamel is more resistant to colonization by bacteria.
• It also inhibits bacterial glycolysis by oxidizing the thiol group of enzymes involved in the process. It is available as a component of toothpaste and mouthwash. The adverse effect is staining of the teeth.

Enzymes

• Amyloglucosidase and glucose oxidase activate the lactoperoxidase system in saliva, which converts salivary and exogenous thiocyanate to hypothiocyanite.
• The hypothiocyanite formed has an inhibitory effect on bacterial growth. Enzymes like dextranases, mutants, and proteases are plaque-removal agents; but they cause mucosal erosion.

Metal Ions

Zinc ions in the form of citrate and chloride are used as antiplaque agents in toothpaste and mouthwash. Zinc ions inhibit the conversion of glucose to lactic acid by inhibiting enzymes of glycolysis in bacteria. They also inhibit enzymes required for glucose uptake by S. sanguis and S. mutans.

Triclosan

• It has a broad spectrum of antibacterial effects. It damages the bacterial cytoplasmic membrane, leading to leakage of cellular contents. It also has anti-inflammatory effects.
• Optimal antiplaque effect is achieved when triclosan is combined with a copolymer.
• The latter increases the period of retention of triclosan in the oral cavity. Triclosan does not cause staining of the teeth. It is present in toothpaste and gels.

Chlorhexidine

• It has anti-inflammatory and a broad-spectrum antibacterial effect. It has prolonged oral retention time. Its antiplaque action is decreased by stannous fluoride and sodium lauryl sulfate. Rinsing with chlorhexidine should be avoided after use of toothpaste.
• Best effects are obtained if it is used as a mouth rinse twice daily along with other hygienic measures and professional care. Drawbacks are its taste and ability to cause staining of the teeth and tongue.

Essential Oils

Essential oils like thymol, menthol, and eucalyptol affect bacterial cell walls to produce antibacterial activity. They help to reduce plaque.

Quaternary Ammonium Compounds

• They alter the permeability of the bacterial cell membrane resulting in leakage of cell contents. They are effective against both gram-positive and gram-negative bacteria.
• They are used as mouth rinses. They have a short retention time in the oral cavity.

Others

Sodium lauryl sulfate produces an antiplaque effect by inhibiting the enzyme glucosyltransferase, which plays a role in colonization of enamel by S. mutans. Sanguinarine, an alkaloid, has doubtful efficacy as an antiplaque agent, and because of its unpleasant taste is not used much.

Disclosing Agents

Agents applied to teeth to reveal the presence of dental plaque (identify plaque). The coloration produced is temporary and makes the plaque visible. Disclosing agents are nonirritants. They are as follows:

1. Erythrosine: Most widely used red dye – causes red staining of plaque.
2. Fluorescent disclosing agents: For example, 0.75% sodium fluorescein solution plaque appears bright yellow in normal light and intensive yellow-green under blue light.
   • The disadvantage is the requirement of a special light source or filter mirror.
   • Fluorescent-containing dye is ideal for patients who find erythrosine staining objectionable.
3. Two-tone dye: It is a multi-coloring disclosing agent. Older plaque stains blue, newer plaque stains red.
   • Disclosing agents are available as tablets or liquids. The tablet is chewed, swished, and spit out. Liquid is applied on the teeth with a cotton-tipped applicator or can be rinsed with a small amount of water and spit out.
   • Patient should be informed that there will be a change in color of oral cavity by the agent, which is temporary.

Bleaching Agents

• Tooth whitening or bleaching has become a popular aesthetic dental treatment. Though both terms are used interchangeably, ‘whitening’ refers to the restoration of normal tooth color, whereas ‘bleaching’ results in whitening of the teeth beyond their natural colour.
• Surface whiteners remove surface stains. Bleaching agents are used to remove deep (intrinsic) and surface (extrinsic) stains on the teeth. Tetracycline and high levels of fluorides cause intrinsic staining of the teeth.
• Extrinsic staining can occur due to aging, smoking, beverages, food, trauma, etc. Demineralization in caries can cause both intrinsic and extrinsic staining of teeth.
• Bleaching agents can be administered either by the dentist in office or by the patients themselves at home. They are used in the form of trays, strips, toothpaste, mouth rinses, gums, gels, paint-on products, etc.
• Ideally, tooth bleaching should be done after a proper dental examination and diagnosis, and under professional supervision.
• The result of bleaching depends on the type of stain, concentration and contact time of the bleaching agent, frequency of application and age of the patient.

The commonly used bleaching agents are primarily peroxides – carbamide peroxide and hydrogen peroxide.

1. Hydrogen peroxide: Hydrogen peroxide breaks down into water and free oxygen radicals. The free radicals bind to the stain and decolorize it through an oxidation reaction. The liberation of nascent oxygen is accelerated by the application of heat or light. Hydrogen peroxide-containing mouth rinse and strips are available.
2. Carbamide peroxide (concentration between 10% and 38%): On contact with saliva, it breaks down to liberate hydrogen peroxide (it is the active bleaching agent) and urea. Application of 10% carbamide peroxide in a tray worn for 2 weeks is a commonly used bleaching procedure. A paint-on liquid and gel containing carbamide peroxide is available.
3. Sodium perborate: It releases hydrogen peroxide and sodium metaborate. It is combined with hydrogen peroxide (synergistic effect) for internal bleaching (teeth is brightened from the inside – carried out in devitalized teeth).
4. Calcium peroxide: It reacts with acid to release hydrogen peroxide. Toothpaste containing calcium peroxide is available.
5. Sodium thiosulfate: It is used for removing iodine stains. It is a reducing agent.
6. Silica: A nonabrasive agent used in toothpastes.

Adverse effects: Tooth sensitivity is a common adverse effect following use of peroxide.

• It is due to the penetration of peroxide through the enamel into the pulp. It is usually common in those with a history of tooth sensitivity, use of high concentration, or frequent use of peroxide.
• It subsides after treatment is stopped. Sensitivity depends on the concentration of peroxide and the duration for which it is in contact with the teeth.
• Desensitizing agents like potassium nitrate and fluorides can be used to manage tooth sensitivity.
• Peroxides can alter the calcium and phosphorus content of dental hard tissues, resulting in a decrease in the microhardness of enamel.
• They can affect the soft tissues and cause gingival irritation. They also affect restorative materials. Following treatment of teeth with bleaching agent, there is a decrease in the enamel composite resin bond strength. They can alter the colour of filling materials resulting in a mismatch of colour of teeth with filling material.
• Those who are allergic to peroxides should not use them. Discoloration of teeth could be a manifestation of undiagnosed underlying disease.
• Unsupervised use of these agents could mask the underlying disease. There have been concerns of carcinogenicity following use of hydrogen peroxide, but it has not been substantiated so far.
• Dentifrices containing nonbleaching whiteners are available. Nonbleaching whiteners remove surface stains by physical or chemical action. They include:

1. Abrasives, for example, small particles of calcium carbonate, sodium bicarbonate, and silica, which can mechanically remove stains from the surface of the teeth. Some abrasives can damage the dentine.
2. Enzymes, for example, papain – a protease that hydrolyses peptide bonds.
3. Dimethicone makes the surface of the teeth smooth and prevents stains.

Whitening products are available as gels, toothpaste, mouthrinse, strips, and chewing gum. There is an increasing use of laser for whitening of teeth now.

Obtundents

Agents that diminish or abolish dentine sensitivity are obtundents. An ideal obtundent:

1. Should be nonirritating to the pulp.
2. Should be rapid acting.
3. Should be easy to apply.
4. Should not stain the teeth.

Mechanism of action: Obtundents act by

1. Precipitating proteins within dentinal tubules, for example, silver nitrate, zinc chloride, ethyl alcohol, paraformaldehyde, etc.
2. Paralyzing sensory nerve ending, for example, phenol, camphor, menthol, and thymol.

Commonly used obtundents:

1. Zinc chloride: It is an astringent and acts mainly by precipitating proteins in the dentine. It does not stain the teeth.
2. Silver nitrate: It precipitates proteins but stains the teeth black.
3. Ethyl alcohol (70%): It acts by precipitating proteins. It is nonstaining.
4. Thymol, camphor, and menthol: They are volatile oils used in combination and act rapidly. They cause initial stimulation and later paralyse the sensory nerve endings.
5. Clove oil: It initially stimulates and then paralyses the sensory nerve endings. It may stain the teeth. Eugenol is the main constituent of essential oil obtained from cloves.
6. Phenol: It acts by paralyzing sensory nerve endings. It acts rapidly and does not stain healthy dentine.
7. Paraformaldehyde: It liberates formaldehyde, which precipitates proteins. It is slow-acting. It may penetrate the pulp and cause inflammation.

Uses: Obtundents are used to make excavations painless. They are also used to reduce pain in alveolar osteitis – a gauze containing eugenol (clove oil) along with lignocaine is packed into the affected socket; pain is relieved within minutes.

Disadvantage: Irritant obtundents may shrink the pulp.

Mummifying Agents

Agents used to harden and dry the soft tissues of the pulp and root canal. They have antiseptic and astringent properties. Commonly used mummifying agents:

1. Tannic acid: It is an astringent and precipitates proteins. The tissues are hardened and become resistant to bacterial infection. It may be used alone or in combination with iodoform or eugenol and glycerine.
2. Iodoform: It has antiseptic and weak local anesthetic properties. It decomposes to liberate iodine. It is used as a paste in combination with phenol, glycerine, and eugenol.
3. Liquid formaldehyde: It is an irritant, so it is not used alone. It can cause necrosis of oral tissues. It is used in combination with zinc oxide, thymol, local anesthetic, and glycerine as a paste.
4. Paraformaldehyde: It acts by liberating formaldehyde. It is used as a paste in combination with zinc oxide/zinc sulfate and cresolate.
5. Cresol: It is used in combination with thymol and zinc oxide as a paste.

• Mummifying agents are used when the devitalized pulp and contents of root canal cannot be removed. The disadvantage with the use of mummifying agents is the possibility of a secondary infection due to retained dead tooth pulp.
• However, now with the practice of root canal therapy, the dry canal is packed with a resin sealant following pulpectomy.

Mouthwashes (Mouthrinses)

• A mouthwash is an aqueous solution used to rinse the oral cavity and maintain oral hygiene. Ideal properties of a mouth rinse include low cost, low toxicity, palatability, adequate penetration into plaque, adequate retention at the site of disease, entry into less-accessible areas, stability on storage, and effective antibacterial activity.
• Cosmetic mouthwash may temporarily suppress bad breath and refresh the mouth with a pleasant taste. Therapeutic mouthwash can help reduce plaque, gingivitis, caries, and bad breath.
• Mouthwash contain antiseptics (phenolic compounds, bisbiguanides, quaternary ammonium compounds, triclosan, halogens, oxygenating agents), astringents, antiplaque, antitartar, anticaries, desensitizing agents, sweeteners, flavouring, coloring agents, detergents, odour neutralizers, etc.

Bisguanide:

• Chlorhexidine gluconate is a widely used oral product. It is a cationic bisbiguanide that has an antimicrobial effect. It decreases pellicle formation and colonization of enamel by bacteria. It can reduce plaque and gingivitis. It has good substantivity.
• Adverse effects include unpleasant taste, staining of teeth and restorative materials, calculus deposition, mucosal irritation, and taste disturbances. Its efficacy is decreased by sodium lauryl sulfate; hence, it should be used 30 min to 2 h after use of toothpaste.

Essential oils:

• Phenolic compounds containing essential oils like thymol, eucalyptol, and menthol kill microorganisms by damaging their cell membrane and inhibiting their enzymes. They scavenge free radicals and also slow down maturation of plaque.
• They are useful for the prevention of plaque, gingivitis, and halitosis. Mouthwashes containing essential oils have been used as an adjunct to brushing and flossing to prevent and control plaque formation and gingivitis. Mouthwashes having essential oils contain ethanol.
• They should not be used in patients with xerostomia or oral mucosal disease because ethanol can cause mucosal irritation and dryness.

Quaternary ammonium compounds:

• For example, cetylpyridinium chloride and domiphen bromide. Cetylpyridinium chloride is a cationic agent that binds to and disrupts the bacterial cell membrane.
• It has been shown to reduce plaque but is less effective and has a lower substantivity than chlorhexidine. Adverse effects include the staining of teeth and the formation of calculus.

Germicide:

Triclosan is a broad-spectrum antibacterial agent that acts by disrupting the microbial cell membrane. It inhibits cyclooxygenase and lipoxygenase to produce an anti-inflammatory effect. It is used in combination with a polymer to improve its antiplaque activity and surface retention.

Oxygenating agents:

• For example, hydrogen peroxide and sodium perborate. They are broad-spectrum antimicrobials. Hydrogen peroxide is a strong oxidizing agent. Preparations containing sodium perborate are available; it reacts with water to produce hydrogen peroxide and borate.
• They liberate oxygen, which removes light stains and kills anaerobes. They have been shown to reduce gingivitis. They can be used for stain removal and prior to prosthodontic treatment to decrease gingival inflammation.

Povidone-iodine:

It is a broad-spectrum antimicrobial agent – active against bacteria, fungi, protozoa, and viruses. It can reduce plaque and gingivitis. It is useful as an adjunct with brushing for prevention of plaque formation. It also reduces severity of radiation-induced mucositis.

Fluorides:

For example, sodium fluoride, stannous fluoride, or acidulated phosphate fluoride. They promote re-mineralization and make the enamel resistant to acid attack. They are prescribed for patients who are at high risk of dental caries. Fluoride mouthwashes are avoided in children less than 6 years of age, as the risk of ingestion is high.

Alcohol:

Ethyl alcohol is used in mouthwash as an antiseptic, preservative, and solvent. Alcohol-free mouthwashes are available. High concentrations of alcohol can cause mucosal irritation, ulceration, and pain.

Detergents:

• For example, sodium lauryl sulfate and sodium lauryl sarcosinate. They reduce the surface tension in the oral cavity, thus, allowing other ingredients of mouthwash to come in contact with the teeth easily. They have an antiplaque effect.
• By their foaming action, they help to remove food debris from the oral cavity. Sodium lauryl sulfate is a commonly used detergent. Its disadvantage has been the occurrence of aphthous ulcers in some patients.
• Sodium lauryl sarcosinate is another detergent that is less irritant to the mucosa. Detergent-free mouthwashes are available.

Astringents:

For example, zinc chloride, zinc sulfate, and tannic acid. They precipitate proteins in the cells to form a protective coat. They are useful in ulcerative gingivitis, aphthous ulcers, and chronic alveolar abscesses.

Antitartar agent:

Zinc compounds prevent build-up of tartar.

Flavoring agents:

They are menthol, eucalyptol, peppermint, etc. They improve the flavour of mouthwash, mask the unpleasant taste of ingredients like sodium lauryl sulfate and provide a sense of freshness inside the mouth.

Sweeteners:

Saccharin, sucralose, sorbitol, and xylitol are used to impart a mild sweet taste to the mouthwash.

Preservatives:

Sodium benzoate and methylparaben are used as preservatives to prevent the growth of microorganisms.

• Coloring agents are also used in mouthwashes to improve their appearance.

Others:

Benzydamine hydrochloride:

It has analgesic, anti-inflammatory, antimicrobial, and anesthetic properties. It acts by inhibiting prostaglandin synthesis and decreasing cytokine production by macrophages. It has been shown to reduce the severity and duration of radiation-induced mucositis for which it is recommended.

Antibacterial peroxidase:

Mouthwashes may contain enzymes that act against bacterial peroxidases. The enzymes include glucose oxidase, lactoperoxidase, and lysozyme. They can be used for gingivitis and halitosis. These mouthwashes have a low pH, which may result in dental erosion following prolonged use.

Sodium bicarbonate:

It is useful in patients with oral ulcers, as it does not irritate the oral mucosa. It increases the pH of saliva and suppresses the growth of S. mutans. Anaerobic bacteria produce volatile sulfur compounds, which results in bad breath. Sodium bicarbonate helps to neutralize and mask bad odors.

Uses of mouthwash

1. To reduce plaque formation.
2. In gingivitis, dental caries and stomatitis.
3. To relieve soreness of teeth and gums following flossing and use of dentures.
4. To reduce bad breath (halitosis).
5. To keep the oral cavity moist in xerostomia, as lack of saliva increases the risk of tooth decay.
6. To treat oral burns, aphthous ulcers, alveolar osteitis (dry socket) and mucositis following cancer chemotherapy and radiotherapy.
7. To maintain oral hygiene in persons who are unable to brush adequately owing to their physical disability.

The mouthwash should be swished in the mouth for about 1 min twice/thrice daily and spit out. It should not be swallowed. Patient should be advised not to eat, drink or rinse their mouth for at least 30 min after using a mouthwash.

Side effects

• Mouthwash may contain ingredients that cause mucosal irritation and ulcers. They can cause taste disturbances and staining of teeth due to the restorative materials used.
• Allergy can occur to ingredients of mouthwash. Swallowing of fluoride-containing mouthwash can lead to fluoride toxicity. Too much ingestion of alcohol-containing mouthwash can be dangerous in children.
• There has been concern about the possible risk of oral cancer on long-term use of mouthwash due to alcohol present in it. Excessive use of mouthwash can damage the normal flora in the oral cavity.

Sialagogues

Sialagogues are drugs used to augment salivary secretion. They are mainly used in the treatment of xerostomia (dry mouth) that follows head and neck radiation treatment or use of certain medications (for example, antidepressants, antipsychotics, anticholinergics).

If not treated, xerostomia can lead to secondary fungal infections, dental caries, halitosis, burning mouth, etc. The following drugs used in the treatment of xerostomia:

1. Pilocarpine, a cholinergic alkaloid; is used at a dose of 5 mg orally three times daily with food. It is also used in Sjogren’s syndrome, an autoimmune disorder characterized by dryness of all mucosae (dry eyes, mouth, etc.).
2. Cevimeline, an M3 agonist, can also be used to treat xerostomia and dry eyes. It is longer acting and has fewer side effects compared to pilocarpine. It is used at a dose of 30 mg t.d.s.
3. Bethanechol, a cholinergic drug can also be used in dry mouth.
4. Intraoral topical agents like chewing gums, saliva stimulants, and saliva substitutes can also be used. Sugar-free chewing gums and candies which are commercially available can increase salivary flow.
   • An oral spray containing malic acid and ascorbic acid have been used as salivary stimulants.
   • Salivary substitutes improve viscosity and mimic natural saliva. They usually contain minerals like fluoride, phosphate, and calcium; carboxymethylcellulose, flavouring agents, and preservatives.

Antisialogogues

Antisialogogues are drugs used to treat sialorrhoea (hypersalivation). They include:

1. Glycopyrrolate is a synthetic derivative of atropine. It can be used to decrease salivary secretion during dental procedures and heavy metal poisoning. It is used at a dose of 1–2 mg.
2. Scopolamine patches can be tried. By blocking cholinergic activity, it suppresses sialorrhoea.
3. Botulinum toxin A: It can be injected into salivary glands under ultrasound guidance to control sialorrhoea.