Bleaching

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Bleaching

  1. 1. INTRODUCTION A beautiful smile is probably one of the most captivating attribute that a person can possess. But certain discoloration or stains could abstain a person from doing so. In this age everybody wants a perfect dentition with sparkling white teeth. Now this could pose a challenge to the dentist but with the advent of various bleaching materials and techniques it is possible to transform an unaesthetic smile to an aesthetic one. HISTORY: • First century Roman physicians maintained that brushing teeth with urine, particularly Portuguese urine, whitened teeth. Barber surgeons, after abrading the enamel with coarse metal files, applied “aqua fortis”, a solution of nitric acid, to whiten the teeth. This practice continued till the eighteenth century. ● Guy de chaulic, a 14th century surgeon produced a set of rules for oral hygiene which included the following tooth whitening procedures. “Clean the teeth gently with a mixture of honey and burnt salt to which some vinegar has been added.” • In 1877, Chapple proposed Oxalic acid as the bleaching material of choice. • In 1888, Taft suggested calcium hypochlorite as an effective whitening solution. • In 1884, Harlon used hydrogen dioxide as a whitening agent. • In 1895, electric currents and UV rays were used for whitening teeth. • In 1916, Kane used acid to dissolve brown fluoride stains. He used 18%hydrochloric acid to dissolve the superficial layers of enamel.
  2. 2. • In 1918, Abbot pioneered the dental effects of superoxol. He found that while the chemical was suitable for bleaching teeth, its action could be greatly enhanced by the addition of heat and light. Some of the techniques used today are based on Abbot’s findings. • In 1958, Pearson succeeded in bleaching Non-vital teeth. He sealed superoxol within the pulp chamber and stated that within 3 days, the oxygen releasing capacity of the solution had whitened the experimental teeth to some degree. In 1967, Nutting and Poe refined this method as “walking bleach”. In this method, a 30% mixture of superoxol and sodium perborate was left in the pulp chamber for up to one week. This technique is limited to endodontically treated teeth. • In 1984, Zaragoza bleached maxillary and mandibular arches simultaneously with 70% hydrogen peroxide and heat. • In 1989, a new procedure was developed by Heywood and Heymann whereby a stabilized solution of carbamyl peroxide or per hydroxyl urea is placed in a molded tray, which the patient places over his teeth for hours at a time. This gentle solution works to gradually whiten the teeth in a much more predictable, safe manner than the previous bleaching methods. • In 1989, Croll introduced hydrochloric acid paste for superficial enamel restoration. • In 1996, Lasers were used with a patent system of chemicals by Reyto. NATHOO (1997) CLASSIFICATION OF EXTRINSIC STAINS 1. N1 TYPE DENTAL STAIN (direct dental stain)
  3. 3. The chromogen binds to the tooth surface to cause tooth discoloration. The colour of the chromogen is similar to that of dental stain. These stains can be prevented by good oral hygiene and can be easily removed with prophylaxis paste or tooth paste. 2. N2 TYPE DENTAL STAIN (direct dental stain) The chromogen changes color after binding to the tooth. Ex: Food that has aged and the age-related formation of yellowish discoloration on the interproximal or gingival areas and increases in brown pellicle. N1 type of food stains are known to darken to N2type stains. N2 type stains are more difficult to remove and may require professional cleaning. 3. N3 TYPE DENTAL STAIN (indirect stain) The prechromogen binds to the tooth and undergoes a chemical reaction to cause a stain. Ex: Dental stains from therapeutic agents such as stannous fluoride. Discoloration is due to redox reaction between stannous ions and the sulphhydryl groups in the pellicle proteins. These are most difficult to remove and probably require oxygenating agents such as carbamide peroxide. Tea and coffee in the freshly prepared state cause more staining of teeth and restoration than instant brands. Tea stains glass ionomer more than coffee does. Chlorhexidine+ tea= more stains Chlorhexidine+ coffee= less stain. CLASSIFICATION OF STAINS According to Ilan Rotstein PATIENT RELATED CAUSES DENTIST RELATED CAUSES
  4. 4. - Pulp necrosis ENDODONTICALLY RELATED - Intrapulpal haemorrhage - Pulp tissue remnants - Dentin hyper calcification - Intra canal medicaments - Tooth formation defects - Obturation materials - Drug-related defects RESTORATION RELATED - Amalgam - Pins and posts - Composites EXTRINSIC STAINS Long chain polysaccharides and proteinaceous materials create a tenacious coating on the exposed surfaces of teeth called pellicle. The pellicle occurs along the gingival margin and interproximal areas which are less accessible to tooth brushing. The pellicle is easily stained and may display many colours ranging from white to red to green and can become extremely opaque depending on the source of the pigmentation. Extrinsic stains can be - Dental caries - Bacterial - Dietary -Gingival haemorrhage -Chlorhexidine - Marijuana, chewing tobacco, beetle nut, etc. 1. DENTAL CARIES: It is the most common cause of external and internal discolouration of enamel and dentin. The shade is related to the rate of the carious destruction. 2. BACTERIAL STAINS: Chromophilic bacteria frequently seen in the deciduous or mixed dentition can cause a dotted or black line stain. These types of bacteria are associated with lower than normal caries rates and that removal may result in recolonization of the oral cavity by a more cariogenic flora.
  5. 5. 3. DIETARY REALTED STAINS: The consumption of strong tea or coffee immediately preceded by orange or grape fruit juice is a common dietary cause of external stains. Cola drinks acts by both etching and staining the tooth structure simultaneously. 4. GINGIVAL HEAMORRAGE: Gingivitis (chronic) may induce staining from the breakdown of blood in the gingival sulcus. 5. CHLORHEXIDINE: It acts in reducing plaque formation by disturbing matrix formation of the primary pellicle. This altered pellicle attracts more extrinsic stain not readily removed by tooth brushing. 6. MARIJUANA AND TOBBACCO: Smoking marijuana may produce characteristic linear, green circumferential rings at the cervical margins. Smoking tobacco produces yellow brown discolouration especially on the lingual aspect of teeth. Chewing tobacco causes a black brown stain noticeable on the buccal surfaces of the mandibular posterior teeth. INTRINSIC STAINS: These stains are the result of colour changes of the internal structures of the teeth caused by factors of either systemic or local origin. Intrinsic stains are not only more difficult to treat but because they are distributed through out the tooth, they are more apparent than many extrinsic stains. It can be broadly divide into 2 groups A. Stains caused during odontogenesis B. Stains caused during post eruptive period. A. Stains caused during odontogenesis: During odontogenesis period, teeth may incorporate discolorations in to the enamel or dentin through a change in quantity or quality of these tissues, or by the addition of pigments to their structure.
  6. 6. B. Stains caused during post eruptive period. During the post eruptive period, the teeth can become intrinsically discoloured when discolouring agents are integrated into the hard tissues either from pulp chamber or the tooth surface. INTRINSIC DISCOLORATION CAUSED DURING ODONTOGENESIS 1. ALKAPTONURIA Alkaptonuria is also known as phenylketonuria and ochronosis. It is a recessive genetic deficiency resulting in incomplete oxidation of tyrosine and phenyl alanine, causing an increased level of homogentisic acid. This condition sometimes causes a dark brown pigmentation of the permanent teeth. 2. AMELOGENESIS IMPERFECTA It is genetic defect affects both the primary and permanent dentitions. It can be autosomal recessive or autosomal dominant. This is further divided into - Hypo maturation -Hypocalcific -Hypoplastic Hypo maturation: The enamel has chipped away from the underlying dentin. In the hypo maturation type, the enamel shows autosomal dominant mode of inheritance. Hypocalcific: The enamel found in this group exhibits normal thickness, but it is soft. Often the enamel is completely abraded away soon after eruption. This results in a tooth with a crown that ranges in appearance from a dull opaque white to a dark brown. In addition, these teeth are usually rough and pitted.
  7. 7. Hypoplastic: Enamel found in this group is usually quite thin, often to the point of eliminating interproximal contacts. They usually have a smooth, hard, yellow appearance, although some pitting is found on occasion. 3. DENTINOGENESIS IMPERFECTA This inherited trait is the most prevalent hereditary dystrophy affecting the structure of teeth. It usually affects the primary dentition more seriously than permanent dentition. The clinical crown appear reddish brown to grey opalescent. Often the enamel is friable, and breaks off soon after eruption. The exposed softened dentin then rapidly abrades away. 4. ENDEMIC FLUROSIS This results from the presence of excessive systemic fluoride during enamel matrix formation and calcification. Fluorosis is actually a form of enamel hypoplasia, hence the white spotting. Darker stains occur only after tooth eruption through extrinsic staining of the hypoplastic enamel. Black thought that the stain was caused by the replacement of the normal cementing substance between enamel rods by “BROWNIN”. Dental fluorosis is often found in communities in which the fluoride content of the drinking water exceeds 1PPM.Teeth can be affected from second trimester in utero through age 9. Staining is usually bilateral and affects multiple teeth in both arches. Fluorosis presents as mild, intermittent white spotting, chalky or opaque areas, yellow or brown staining of varying degree and in most severe cases surface pitting of the enamel. 5. ERYTHROBLASTOSIS FAETALIS This is a blood disorder of the neonate due to Rh incompatibility of the maternal blood supplies. It is characterized by agglutination and hemolysis
  8. 8. of the erythrocytes, resulting in free blood pigments. These pigments sometimes discolour all the teeth which are in formation at that time. The affected teeth can range in colour from brown to greenish blue. This condition is usually self treating and the staining resolves as the child matures. 6. PORPHYRIA It is a rare condition which is usually genetically transmitted, although it may develop later in life. This is a disorder of porphyrin metabolism which results in increased formation and excretion of porphyrins. The disease exhibits neurological, psychological and gastro intestinal symptoms. The haematoporphyrin pigment creates a characteristic reddish brown discoloration of the teeth termed “ERYTHRODONTIA” More common in primary dentition. Coloration is dispersed through out the enamel, dentin and cementum and fluoroses red under UV light. 7. SICKLE CELL ANAEMIA AND THALLASSEMIA They are blood dyscrasias results in discoloration similar to erythroblastosis fetalis. But the discolouration from these two dyscrasias is more severe and do not improve with time. 8. TETRACYCLINE STAINING The broad spectrum tetracycline group of antibiotics was first introduced in 1948, for use in the treatment of respiratory illnesses. But tooth discolouration caused by incorporation of systemic tetracycline into tooth structure was first reported by Schwashman and Schuster in 1956.
  9. 9. Tetracycline can cross placental barrier, affecting both deciduous and permanent dentition. Exposure of as short as 3 days can cause discolouration of the teeth anytime from 4 months in utero through age 9. MECHANISM: Tetracycline binds to calcium in the tooth through a chelation process forming tetracycline-calcium-phosphate complex which is subsequently incorporated into the hydroxyapatite crystal of tooth during the mineralization stage of development. It is found through out the tooth but greatest concentration is in the dentin near dentinoenamel junction, because of large surface area of the dentin apatite crystals compared to enamel apatite crystals. The colour of the affected teeth gradually changes over a period of time, especially in those teeth which are most exposed to light, the facial surfaces of anterior teeth. Wallman and Hilton clearly demonstrated the role of light in1962, by splitting a tetracycline stained tooth length wise and exposing only one half to light. The half which was exposed to light underwent a colour change, becoming brown, while the half which was unexposed to the light remained yellow. Therefore many researchers feel that the use of heat and light bleaching systems in the treatment of tetracycline stained teeth may be contraindicated. In 1983, Davies, et al postulated that tetracycline incorporated into hydroxyapatite, when oxidised by light (photo-oxidation) produces the red- quinone product, 4α, 12αanhydro-4-oxo4-dedimethylamino tetracycline.
  10. 10. APPEARANCE Yellow, yellow brown, brown, gray or blue. Intensity of staining varies widely, distribution is diffuse .severe cases may exhibit banding Usually bilateral and affects multiple teeth in both the arches. The hue and severity of tooth discoloration depends upon four factors associated with tetracycline administration. 1. Age at time of administration Anterior primary teeth are susceptible to discolouration by systemic tetracycline from 4 months in utero through 9 months postpartum. Anterior permanent teeth are susceptible from 3 months postpartum through age 7 years. 2. Duration of administration. The severity of the staining is directly proportional to the duration of administration of the medication. 3. Dosage The severity of the staining is directly proportional to the administered dosage. 4. Type of tetracycline. A. chlortetracycline (Aureomycin)-gray brown stain. B. dimethylchlortetracyclin (ledermycin)-yellow stain. C. doxycyclin (vibramycin)-does not cause staining. D. oxytetracyclin(terramycin)-yellow stain. E. tetracycline (achromycin)-yellow stain. STAINS CAUSED DURING POST-ERUPTION PERIOD 1. AGE
  11. 11. Several non-pathologic conditions which are related to the process of aging work gradually to discolor the teeth overtime. The natural process of gradual pulp withdrawal with the formation of secondary dentin causes the development of a yellowish –brown colour. Treatment: strongest indication for tooth whitening. Results are more rapid and predictable. 2. DENTAL METALS The most ubiquitous source of staining from dental metals is the leeching of corrosion products from amalgam. Another source of similar staining is threaded stainless steel pins or gold plated retentive pins. These stains can be extremely dark and pose a significant challenge for any whitening efforts. Treatment: Replace dental metals by composite or porcelain restoration. Remove the retentive pins. Bonding. 3. FOODS AND BEVERAGES Smoking, tea, coffee, and chewing tobacco stain teeth. The degree and quality of the staining is directly related to the type, frequency, and length and exposure to staining agents. Treatment: Vital tooth whitening 4. IDIOPATHIC PULPAL RECESSION A tooth remain vital but usually display a yellow to brown darkening similar to that of a non-vital tooth. But the tooth’s actual condition can be differentiated on the basis of vital testing. Radiographically these teeth show greatly diminished pulp chamber size. 5. NON-ALLOY DENTAL MATERIALS Many of the materials which we use routinely have the potential for causing discoloration of teeth.Ex: Eugenol, Formocresol, Root canal sealer. 6. TRAUMATIC INJURY
  12. 12. Trauma to the tooth occasionally results in internal hemorrhage. Bilirubin is diffused into the dentinal tubules causing a pink discoloration which usually is followed by the development of a diffuse reddish-brown stain. If the pulp is able to avoid necrotic degeneration, the natural color of the crown returns within a few weeks after the injury. If the pulp degenerates, the natural color will not return, and the discoloration can darken. In some case a slowly growing pink spot on the enamel indicates ongoing internal resorption. Treatment:- - Wait till tooth has recovered from trauma. - Sometime natural color will return without intervention. - After vitality test, radiograph should be taken. - If the tooth is vital without internal or external resorption, tooth whitening can be instituted. - If tooth is non-vital=RCT+non vital bleaching. - If tooth is vital but exhibits internal resorption, RCT can be instituted and non-vital bleaching begun. INDICATION OF BLEACHING There are certain discoloration of teeth in which bleaching used alone is most likely to be an adequate treatment. These are- 1. Discoloration is fairly light. 2. Age related discoloration. 3. Evenly distributed discoloration. 4. To match color of prosthesis. 5. Discoloration due to chlorhexidine treatment. CONTRAINDICATION OF BLEACHING FOR VITAL TEETH
  13. 13. 1. Extremely large pulps. 2. Hypersensitivity-This can be due to exposed root surfaces or cervical eroded areas or recent completion of orthodontic tooth movement. They can be a contraindication to bleaching as transient pulp hyperemia may be associated with such cases. In such cases treatment for hypersensitivity should be done first. 3. Severe loss of enamel-opaque flourosis, flourosis staining with pitting may be associated with reduced thickness of enamel which may contraindicate bleaching. 4. Extensive restorations- Bleaching agents may roughen restorative material if they come in contact with them. Greatest damage to GIC and least to porcelain. This is more significant in matrix bleaching in which teeth have longer exposure to the chemicals. CONTRAINDICATION OF BLEACHING FOR NON-VITAL TEETH 1. Pregnancy and lactating mothers. 2. Peroxide allergy-carefully applied rubber dam can help prevent reaction. 3. Root resorption- presence of external or internal root resorption may not be good indication for bleaching. BLEACHING MATERIALS 1. HYDROGEN PEROXIDE It is available in various concentrations, but 30%-35% stabilized aqueous solutions are the most common. Silicone dioxide gel forms containing 35% hydrogen peroxide are also available, some of them activated by a composite curing light. 2. SODIUM PERBORATE
  14. 14. It is available in powdered form or as various commercial preparations. When fresh, it contains about 95%perborate, corresponding to9.9% of available oxygen. It is stable when dry. In the presence of acid, warm air, or water, it decomposes to form sodium metaborate, hydrogen peroxide, and nascent oxygen. 3 types of sodium perborate are available. 1. Monohydrate 2. Trihydrate 3. Tetra hydrate. These differ in oxygen content It should be the material of choice in most intracoronal bleaching procedures. 3. CARBAMIDE PEROXIDE It is also known as urea hydrogen peroxide , available in the concentration of 3%-45%.10% carbamide peroxide is most commonly used with a mean ph of 5- 6.5.10% carbamide peroxide breaks down into urea, ammonia, carbondioxide,3.5% hydrogen peroxide. Bleaching preparation containing carbamide peroxide usually also include glycerin or propylene glycol, sodium stannate, phosphoric acid or citric acid, and flavor additives. In some preparations, carbopol, a water soluble polyacrylic acid polymer is added as a thickening agent. Carbopol also prolongs the release of active peroxide and improves shelf life. MECHANISM OF BLEACHING The bleaching process is based on the oxidation of the bleaching agent. Oxidation is the chemical process by which organic materials are converted into carbon-di-oxide and water. The oxidation-reduction reaction that takes place in the bleaching process is called the REDOX reaction.
  15. 15. HYDROGEN-PEROXIDE BLEACHING Hydrogen peroxide is an oxidizing agent and has the ability to produce free radicals, HO2 and O, which are very reactive. The HO2 (per hydroxyl) is more potent. In aqueous form, hydrogen peroxide is weakly acidic (to reduce its breakdown and extended shelf life) and ionizes as- H2 O2 → H2 O+O ↓ H+ H O2 (ionization of hydrogen peroxide at acidic PH. In order to promote the formation of H O2 ions, the H2 O2 is buffered to make it alkaline. In alkaline condition (ph9.5-10.8) H2O2 ionizes producing more per hydroxyl (H O2), which results in greater bleaching effect. H2 O2 → H2 O + O ↓ H + H O2 (higher percentage of stronger free radicals) The whitening mechanism of bleaching is believed to be linked to the degradation of high molecular weight and complex organic molecules that reflect a specific wavelength of light and responsible for color of stain. The resulting degraded products are of lower molecular weight and composed of less complex molecules that reflect less light resulting in reduction or elimination of discoloration. Darkly pigmented organic material responsible for enamel discoloration is composed of carbon ring structures with unsaturated, double-carbon bonds. With further oxidation these products are modified to hydrophilic, non pigmented carbon structures with saturated carbon bonds (saturation point).Ideally this is the point at which whitening should be terminated. If
  16. 16. the degradation process continues, however there is a further decomposition of organic matrix, which can lead to complete oxidation with generation of carbon dioxide and water, resulting in total loss of enamel matrix protein. CARBAMIDE PEROXIDE CHEMISTRY Carbamide peroxide is available in conc. of 3%-15%. In dental bleaching, carbamide peroxide is usually used at a conc. of 10%-15%. The carbamide peroxide breakdown into hydrogen peroxide.10% carbamide peroxide produces 3.6%hydrogen peroxide. The resulting hydrogen peroxide then ionizes as previously mentioned. CH2 N2 O H2 O2 ↓ ↓ NH3 H2 O2 + CO2 Carbamide peroxide products contain either a carbopol or glycerin base. The carbopol base slows the release of hydrogen peroxide. Carbamide peroxide precipitation has a slightly acidic ph to extend shelf life. FACTORS THAT AFFECT BLEACHING 1. Surface debridement: Through scaling and polishing should be performed in order to eliminate all superficial debris. 2. Hydrogen peroxide concentration: The higher the conc., the greater the effect of the oxidation process. The highest conc. generally used is 35%. Note: when gelling agents are added to 35% hydrogen peroxide, conc. of hydrogen peroxide is then reduced to 25%. 3. Temperature: an increase of 10degree doubles the rate of the chemical reaction. Generally, if the temperature is elevated to a point at which the
  17. 17. patient doesn’t feel discomfort, then the procedure is taking place at a safe range of temperature. 4. Ph: when hydrogen peroxide is stored and shipped, an acidic ph must be maintained to extend shelf life. The optimum ph for hydrogen peroxide to have its oxidation effect is ph-9.5- 10.8. This produces a 50% greater result in the same amount of time as at a lower ph. 5. Time: The effect of the bleach is directly related to the time of exposure. The longer the exposure, the greater the color changes. 6. Sealed environment: Placing the hydrogen peroxide into a sealed environment has been shown to increase its bleaching efficiency BLEACHING TECHNIQUE FOR ENDODONTICALLY TRATED TEETH The methods most commonly used to bleach endodontically treated teeth are the Walking bleach and the Thermo catalytic technique. Walking bleach is preferred since it requires less chair time and is safer and more comfortable for the patient. A. WALKING BLEACH The walking bleach technique should first be attempted in all cases requiring intracoronal bleaching. It involves the following steps. 1. Familiarize the patient with the possible causes of discoloration, procedure to be followed, expected outcome, and possibility of future rediscoloration. 2. Assess the status of the periapical tissue and the quality of the endodontic obturation with radiograph. Endodontic failure or questionable obturation should always be retreated prior to bleaching. 3. Assess the quality and shade of any restoration present and replace if defective. Tooth discoloration frequently is the result of leaking or discolored restoration. In such cases, cleaning the pulp chamber and replacing the defective restoration is sufficient.
  18. 18. 4. Evaluate the tooth color with a shade guide and if possible, take clinical photographs at the beginning of and throughout the procedure. These provide a point of reference for future comparison. 5. Isolate the tooth with rubber dam. The dam must fit tightly at the cervical margin of the tooth to prevent possible leakage of the bleaching agents onto the gingival tissue. Interproximal wedges and ligatures may also be used for better isolation. If superoxol is used, a protective cream such as orabase or Vaseline must be applied to the surrounding gingival tissues prior to dam placement. 6. Remove all restorative material from the access cavity, expose the dentin and refine the access. Verify that the pulp horns and other areas containing pulp tissue are clean. 7. Remove all materials to a level just below the labial gingival margin. Orange solvent, chloroform or xylene on a cotton pellet may be used to dissolve sealer remnants. Etching the dentin with phosphoric acid is unnecessary and may not improve the prognosis. 8. Apply a sufficiently thick layer, at least 2mm of a protective white cement barrier such as polycarboxylate cement, Zinc phosphate cement, GIC, IRM or cavit, to cover the endodontic obturation. The coronal height of the barrier should protect the dentinal tubules and conform to the external epithelial attachment. 9. Prepare the walking bleach paste by mixing sodium perborate and an inert liquid such as water, saline, or anesthetic solution to a thick consistency of wet sand. With a plastic instrument, pack the pulp chamber with the paste. Remove excess liquid by tamping with a cotton pellet. This also compresses and pushes the paste into all areas of the pulp chamber. 10. Remove excess bleaching paste from undercuts in the pulp horn and gingival area and apply a thick well-sealed temporary filling (preferably
  19. 19. IRM) directly against the paste and into the undercuts. Carefully pack the temporary filling, Atleast 3mm thick, to ensure a good seal. 11. Remove the rubber dam and inform the patient that bleaching agents work slowly and significant lightening may not be evident for several days. 12. Evaluate the patient 2 weeks later and, if necessary, repeat the procedure several times. Repeat treatments are similar to the first one. 13. As an optional procedure, if initial bleaching is not satisfactory, strengthen the walking bleach paste by mixing the sodium perborate with gradually increasing concentrations of hydrogen peroxide (3-30%) instead of water. The more potent oxidizers may have an enhanced bleaching effect but are not used routinely because of the possibility of penetration into the tubules and damage to the cervical periodontium by these more caustic agents. Sodium per borate+ water → sodium metaborate+ hydrogen peroxide+ oxygen THERMOCATALYTIC BLEACHING This technique involves placement of the oxidizing chemical, generally 30-35% hydrogen peroxides (superoxol), in the pulp chamber followed by heat application either by electric heating devices or specially designed lamps. Disadvantages: Cervical root resorption caused by irritation to the cementum and periodontal ligament. This is possibly due to the oxidizing agent combined with heating. Therefore, application of highly concentrated hydrogen peroxides and that during intra coronal bleaching should not be carried out routinely. ULTRAVIOLET PHOTO OXIDATION This technique applied light to the labial surface of the tooth to be bleached. A 30-35% H2O2 solution is placed in the pulp chamber on a cotton
  20. 20. pellet followed by a 2 min exposure to UV light. This causes oxygen release like thermo catalytic bleaching technique. INTENTIONAL ENDODONTICS AND INTRACORONAL BLEACHING: This technique is more helpful in tetracycline staining as the stains are incorporated into dentin and are therefore more difficult to treat from the external enamel surface. This technique involves standard endodontic therapy followed by intracoroanl walking bleach technique. COMPLICATIONS AND ADVERSE EFFECTS TO BLEACHING: 1. External root resorption Clinical reports and histologic studies have shown that intra-coronal bleaching may induce external root resorption. This is probably caused by the oxidizing agent, particularly 30-35% hydrogen peroxides. Mechanism: The irritating chemical diffuses via unprotected dentinal tubules and cementum defects and causes necrosis of the cementum, inflammation of the periodontal ligament and finally, root resorption. The process may be enhanced if heat is applied or in the presence of bacteria. Previous traumatic injury and age may act as predisposing factors. 2. Chemical burns 30% H2O2 is caustic and causes chemical burns and sloughing of the gingiva. When using such solutions. The soft tissues should always be protected with Vaseline or orabase. 3. Damage to restorations H2O2 affects bonding of composite resins to dental hard tissues. Residual peroxide inhibits polymerization and increases resin porosity. Immersion of peroxide treated dental tissues in water at 370 C for 7 days prevents the reduction in bond strength.
  21. 21. 3 minutes catalase treatment effectively removed all of the residual hydrogen peroxides from the pulp chamber. SUGGESTIONS FOR SAFER BLEACHING OF ENDODONTICALLY TREATED TEETH: - Isolate the tooth effectively with rubber dam, interproximal wedges and ligatures. - Protect the oral mucosa by applying creams such as Vaseline or orabase. Apply catalase to oral tissue totally prevents tissue damage caused by H2O2. - In pulp chamber and access cavity is carefully restored with light-cured acid etched composite resin. Light curing is done from labial surface, rather than lingual surface since this result in shrinkage of the composite resin towards the axial walls, reducing the rate of micro leakage. - Verify adequate endodontic obturation, as it provides an additional barrier against damage by oxidizers to the periodontal ligament and periapical tissues. - Use protective barriers to prevent leakage of bleaching agents that may infiltrate between the gutta percha and root canal walls, reaching the periodontal ligament via dentinal tubules, lateral canals, or the roots apex and causing root resorption. - Avoid acid etching - Avoid strong oxidizers - Avoid heat as it may damage the cementum and periodontal ligament as well as dentin and enamel, especially when combined with strong oxidizers. - Recall patient periodically to examine bleached teeth both clinically & radio graphically.
  22. 22. Post-bleaching tooth restoration: After bleaching wait for few days to restore the tooth with composite resin as residual peroxides from bleaching agents may affect the bonding strength of composite. VITAL BLEACHING TECHNIQUES: In these techniques, oxidizers are applied to the external enamel surface of the teeth. I. In-office bleaching technique using light / heat (thermo/photo bleaching) Bleaching solutions used: 30%-35% H2O2 available in 10ml prepacked dosages. Bleaching light: Photo flood lamp – provides light and heat. Rheostat controlled solid state heating device with specially shaped metal tips that provides precise localized heating of bleaching solution on teeth. Procedure: 1. Apply protective cream to surrounding gingival tissues and isolate the teeth with rubber dam and waxed dental floss ligatures. 2. Avoid metal rubber dam clamps if heat lamp is used as they are subjected to heating and may be painful to the patient. 3. Do not inject a local anesthetic. 4. Protect patients and operations eye with protective glass. 5. Oral prophylaxis with pumice and water is done. 6. For severely stained teeth, etching each teeth with 35% phosphoric acid facially and lingually for 10 sec may enhance the penetrability of the bleaching solution and produce the greatest amount of immediate stain reduction. Rinse the teeth with water for 60 seconds.
  23. 23. 7. Place a small amount of 30-35% H2O2 into a dappen dish. Apply the hydrogen peroxide liquid on the labial surface of the teeth using a small cotton pellet or a piece of gauge. Instead of aqueous solution, gel containing H2O2 can be used. 8. Apply heat with a heating device or a light source. The temperature is usually between 1250 F and 1400 F (520 C-600 C).Rewet the enamel surface with hydrogen peroxide as necessary. 9. Remove the heat source and allow the teeth to cool down for at least 5min. Then wash with warm water for 1min and remove the rubber dam. Avoid cold water, as the sudden change in temperature may damage the pulp or can be painful to the patient. 10. Dry the teeth and gently polish with composite resin polishing cup. Treat all of the etched and bleached surfaces with a neutral sodium fluoride gel for 3-5min. 11. Inform the patient about cold sensitivity for 24 hours and use fluoride rinse daily for 2 weeks. 12. Re-evaluate the patient after 2weeks and repeat bleaching if necessary. Complications and adverse effects: - Post-operative pain - Pulpal damage - Dental hard tissue damage - ↓Micro hardness of enamel dentin and cementum - Susceptible to degradation and to secondary caries formation - Mucosal damage – ulceration and sloughing due to oxygen gas bubbles - Prevention – application of protective cream and catalases MOUTH GUARD BLEACHING: This technique is generally used for mild discolorations. It has been basically advocated as a home bleaching technique and there are wide
  24. 24. variations in materials, bleaching agents, frequency and duration of treatment. Bleaching agents commonly used and hydrogen peroxide and carbamide peroxide. Technique: 1. Patient is familiarized with the probable causes of discoloration, the procedures to be followed and the expected outcome. 2. Prophylaxis is performed and the color of the teeth is assessed with a shade guide. Photographs are taken at the beginning of and throughout the procedure. 3. An alginate impression is made of the arch to be treated. The guard is outlined in the cast model. It should completely cover the teeth in arch. Two layers of die relief are placed on the buccal aspects of the cast teeth to form a small reservoir for the bleaching agent. A vaccum formed soft plastic matrix approximately 2mm thick is fabricated and trimmed with crown and bridge scissors to 1mm past the gingival margins. This is then adjusted with an acrylic trimming bur. 4. The mouth guard is inserted to ensure proper fit. The guard is removed and the bleaching agent applied in the space of each tooth to be bleached. The mouth guard is then reinserted over the teeth and excess bleaching agent is removed. 5. The patient is familiarized with the use of the bleaching agent and with the method of wearing the guard. The procedure is performed for 3-4hrs a day, and the bleaching agent is replenished every 30-60min. The patient is informed about possible thermal sensitivity and minor irritation of soft tissues. Discontinue the use of guard if it is uncomfortable. 6. Treatment continues for 4 to 24 weeks. Patient is recalled every 2 weeks to monitor lightening or complications. Look for tissue irritation, oral
  25. 25. lesions, enamel etching and leaky restorations. If complications occur treatment is stopped. COMPLICATIONS AND ADVERSE EFFECTS OF MOUTH GUARD BLEACHING: Systemic effects: - Accidental ingestion of large amount of bleaching gets may be toxic and cause irritation to the gastric and respiratory mucosa. - Bleaching agents containing carbapol, which retards the rate of oxygen release from peroxide, are usually more toxic. - Dental hard tissue damage - Tooth sensitivity: Transient tooth sensitivity to cold may occur during or after mouth guard bleaching. - Transient pulpalgia. - Mucosal damage, possibly from mechanical interference by the mouth guard, chemical irritation by the bleaching active agent and allergic reaction to gel components. - Damage to restoration: Bleaching agents may cause softening and cracking of the resin matrix of composites. It is reported that both 10% carbamide peroxide and 10% H2O2 may enhance the liberation of mercury and silver from amalgam restorations and may increase exposures of patients to toxic by products. So, cover the amalgam restorations with a protective layer of dental varnish prior to gel application. Occlusal disturbances and TMJ pain. LASER-ACTIVATED BLEACHING Recent techniques use lasers for extra coronal bleaching. Types of lasers: 1. Argon laser – emits visible blue light
  26. 26. 2. Carbon-dioxide laser – emits invisible infrared light These lasers can be targeted to stain molecules and, with the use of a catalyst, rapidly decompose hydrogen peroxide to oxygen and water. The catalyst / peroxide combination may be damaging, therefore exposed soft tissues, eyes, and clothing should be protected. Combination of both lasers can significantly reduce intrinsic stains in the dentin. An argon laser can be targeted at stain molecules without overheating the pulp. It is easy to use and is best for removal of initial dark stains such as tetracycline stains. Carbon dioxide laser interacts directly with the catalyst peroxide combination and removes the stain regardless of the tooth color. ALTERNATIVES TO BLEACHING MICRO ABRASION: It is a technique for removing about 25µ of the enamel surface. It is particularly useful for eliminating white or brown spots or surface roughness. Original protocol used 18% HCl and pumice. A proprietary compound consists of water soluble gel containing a dilute conc. of HCl and an abrasive. The gel is applied to the enamel surface with special rubber cups in a contra angle hand piece for about 10sec / tooth and teeth must be well rinsed with water. Assessment is made of color change and degree of tooth removal and the process is repeated as required. When the desired result has been achieved, teeth are rinsed thoroughly with water and the residual solution is neutralized with sodium bicarbonate. The teeth are rinsed again with water, dried, and polished with a fine, fluoride containing prophy paste. The McInnis micro abrasion technique:
  27. 27. A solution of 5 parts 30% H2O2, 5 parts 36% hydrochloric acid, and 1 part diethyl ether is applied directly to the discolored areas for 1-2min. Fine cuttle discs are used over the enamel surface for 15 sec to removes the softened enamel surface. MACROABRASION This technique is used to remove localized, superficial white spots and other surface stains or defects. It uses 12-fluted composite finishing bur and fine grit finishing diamond in a high speed hand piece to remove the defect. Care must be taken to use light, intermittent pressure and carefully monitor removal of tooth structure to avoid irreversible damage to the tooth. Airwater sprays is used as coolant and maintain the tooth in hydrated state to facilitate assessment of defect removal. After removal of the defect, a 30-fluted composite finishing bur is used to remove any facets or striations created by the previous instruments. Final polishing is accomplished with an abrasive rubber point. Review of available light sources: Conventional bleaching light Tungsten halogen curing light Xenon-plasma arc light Argon laser light Diode laser light Conventional bleaching light: supplies energy to enhance bleaching action of H2O2 simply by adding heat. The heat causes vigorous release of O2 and facilitates the dissolution of pigments. It is slow and often uncomfortable to patient. Tungsten-halogen curing light: Initiate a chemical reaction by activating the light sensitive chemicals in bleaching agent. Time consuming process (40-60 secs/tooth).
  28. 28. Xenon plasma-are light: This is a non laser, high intensity light produce great deal of heat. Therefore it is applied of only 3 sec. Greater trauma to pulp because of greater production of heat. THE INSIDE/OUTSIDE BLEACHING This has also been called ‘internal/external bleaching’ (settembrini et al 1997) and the ‘patient-administered intracoronal bleaching technique’ or modified walking bleach technique’ (Liebenberg 1997). The technique combines the intracoronal bleaching technique with the home bleaching technique. PROCEDURE: 1. PREPARATION OF THE BARRIER The non-vital tooth is prepared in the same manner as walking bleach method. Take a pre-operative radiograph to verify the presence of an acceptable root canal treatment and the absence of apical pathology. The tooth is isolated with rubber dam while removing extracoronal restoration.However the rubber dam is not mandatory as the bleaching material is not caustic. As in the intracoronal technique, the gutta-percha is removed to 2-3 mm below the cemento-enamel junction. The object of the gutta-percha removal is to provide space for the barrier. Conventional glass ionomer or a resin modified glass ionomer can be used as barrier over the gutta-percha to prevent the bleach escaping into the root canal system at the CEJ. It has been suggested to place a calcium hydroxide plug of 1mm thickness over the exposed gutta-percha. This prophylactic step aims to maintain an alkaline medium because cervical resorption has been associated with a drop in ph at the cervical level. 2. CLEANING THE ACCESS CAVITY
  29. 29. The access cavity is cleaned and any remaining pup horn constituents removed. The access cavity can be etched merely to clean the internal surface. It does not enhance the bleaching effect. A cotton wool pellet is placed into the access cavity to avoid food packing into it. 3. SHADE ASSESSMENT The pre –operative shade is taken both of the non-vital tooth color and the surrounding teeth and recorded. 4. INSTRUCTIONS FOR HOME BLEACHING The bleaching tray is checked for fit and comfort. The patient is instructed not to bite with the anterior teeth during the duration of the treatment. The patient is sent home with the bleaching instructions and enough bleaching materials. The cotton pellet in the access cavity is removed with a tooth pick before bleaching. The bleaching syringe can be applied directly into the open chamber prior to seating the bleaching tray, or the bleaching material can be applied into the tray with extra material into the space for the tooth with the open chamber. The patient is instructed to remove the excess with a tooth brush or a paper tissue. After the bleaching session, the tooth is irrigated with a water syringe and a fresh cotton wool pellet is inserted back into the tooth. After a meal, the tooth is again irrigated with water to ensure the absence of debris and a fresh cotton wool pellet is inserted. 5. TREATMNT TIMING If the patient can change the solution every two hours, five to eight applications may be all that it is necessary to achieve the desired lightening. 6. REASSESSMENT OF THE SHADE AND BLEACHING RESULTS The patient returns in 3-7 days. The shade changes are assessed. If sufficient lightening has occurred the bleaching procedure may be terminated. 7. SEALING THE ACCESS CAVITY The access cavity is first irrigated with sodium hypochlorite to flush out any remaining debris. The access cavity can then be cleaned using catalase. The
  30. 30. cavosurface margin, the enamel surrounding the access cavity and the pulp chamber dentine are etched for 15 seconds with 37%phosporic acid. Dentin bonding agents are then applied. Acetone based bonding agents are preferred as they have been shown to reverse the effects of bleaching on enamel bond strengths. The access cavity is sealed with a composite restoration using incremental build ups of composite and flowable composites at the base, over the glass ionomer. 8. REVIEW The tooth should be periodically reviewed and a radiograph taken annually to check for any signs of cervical inflammatory process. BENEFITS 1. More surface area is available both internally and externally for the bleach to penetrate. 2. A lower concentration (10%carbamide peroxide with neutral ph) of the bleach is used. 3. This technique will hopefully eliminate the incidence of cervical resorption that has been reported with the conventional intracoronal bleaching technique as most of the potential factors for resorption are reduced. 4. The need to change the access cavity dressing is eliminated as the access cavity is left open. 5. Treatment time is reduced to days rather than weeks if repeated replenishment is used. 6. The patient can discontinue filling the pulp once the desired color has been achieved. 7. Using catalase prior to placement of the restoration can eliminate residual oxygen.
  31. 31. 8. No heat is required to activate the bleaching material. REFERENCES 1. The effect of hydrogen peroxide concentration on metal ion release from dental amalgam. • Al-Salehi SK, Hatton PV, McLeod CW, Cox AG. J Dent. 2007 Feb; 35(2):172-6. The aim of this study was to investigate the effect of hydrogen peroxide (HP) concentration on metal ion release from dental amalgam CONCLUSIONS: Exposure to HP bleaching agent was associated with increased metal ion released from dental amalgams compared to treatment with a control solution. Ion release was in proportion to the peroxide concentration tested, with the highest concentration associated with the greatest metal ion release for all elements investigated. 2. The effect of bleaching on enamel susceptibility to acid erosion and demineralisation. • Pretty IA, Edgar WM, Higham SM. The purpose of this in vitro study was to determine if enamel that had been bleached by carbamide (urea) peroxide gel (CPG) was at
  32. 32. increased risk of either acid erosion or demineralisation (early caries) than un-bleached enamel The results suggest that tooth bleaching with carbamide (urea) peroxide (using commercially available concentrations) does not increase the susceptibility of enamel to acid erosion or caries. CONCLUSION Dental bleaching can be used to correct many tooth discolorations. These discolorations may have been caused by staining, aging, or chemical damage to teeth. Using the latest in bleaching technology, we can offer a safe method for creating a beautiful, "brilliant" smile. In cases of extreme tooth discoloration, crowns or veneers may be the only choice. But because of the low cost of bleaching treatments, bleaching is nearly always worth a solid try. CONTENTS  INTRODUCTION  HISTORY  CLASSIFICATION OF STAINS  INDICATIONS AND CONTRAINDICATIONS  BLEACHING MATERIALS  MECHANISM OF BLEACHING  BLEACHING NON-VITAL TEETH • WALKING BLEACH • THERMOCATALYTIC BLEACHING • ULTRAVIOLET PHOTO OXIDATION • INTENTIONAL ENDODONTICS AND INTRACORONAL BLEACHING
  33. 33. • COMPLICATIONS AND ADVERSE EFFECTS  BLEACHING VITAL TEETH • IN-OFFICE BLEACHING – THERMO/PHOTO BLEACHING • COMPLICATIONS AND ADVERSE EFFECTS • MOUTH GUARD BLEACHING • COMPLICATIONS AND ADVERSE EFFECTS  INSIDE / OUTSIDE BLEACHING  ALTERNATIVE TO BLEACHING • MICROABRASION • MACROABRASION  LASER ACTIVATED BLEACHING  REVIEW OF AVAILABLE LIGHT SOURCES  REFERENCES  CONCLUSION

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