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Endodontics Lecture 12 حسين فيصل الحويزي.د.أ Tooth Discoloration and Bleaching Classification of discoloration 1- Patient related causes a) b) c) d) Pulp necrosis Intrapulpal haemorrhage Dentin hypersensitivity Age 2- Tooth related defects a) Developmental defects Enamel hypocalcification Enamel hypoplasia Systemic conditions Erythroblastosis fetalis High fever Thalassemia and sickle cell anemia Amelogensis imperfecta Dentinogensis imperfecta b) - 3- Drug related defects a) b) Tetracycline Endemic fluorosis 4- Dentist related causes a) Endodontically related Pulp tissue remanants Intracanal medicaments Obturating materials Restoration related Amalgam Pins and posts Composite b) - Patient related causes a) Pulp necrosis: Any irritation to the pulp may result in pulp necrosis and release of disintegration by-products. These may penetrate the dentinal tubules and discolor the surrounding dentin. The degree of discoloration depends on how long the tooth was necrotic. Treatment is by intracoronal bleaching. b) Intrapulpal hemorrhage: When a tooth is subjected to trauma hemorrhage occurs in the pulp. Erythrocytes undergo lysis to products as iron sulphides enter the dentinal tubules and discolor the dentin. This discoloration is difficult to bleach and may be reversible. Treatment is by intracoronal bleaching. c) Dentin hypercalcification: Due to trauma the pulp may form dentin rapidly to decrease the volume of the pulp. Such new dentin increases the yellow appearance of the tooth. Treatment starts with extracoronal bleaching and if not beneficial more aggressive treatment is needed as root canal therapy and intracoronal bleaching or crown the tooth. d) Age: In old aged teeth certain problems occur to the tooth as physiological dentin apposition, thinning and cracking of enamel and incisal wear of the tooth. These problems increase the color of the tooth which can be treated by bleaching. Tooth related defects a) Developmental defects Enamel hypocalcification: The enamel surface is intact with distinct white to brown areas on the facial surface of the tooth. Enamel hypoplasia: The enamel surface is defective and porous. It may be hereditary as amelogenesis imperfect or due infection, tumors or trauma. During enamel formation, proper mineralization of the tooth is affected. Treatment can start by bleaching and later conservative treatment to repair the porous surface. b) Systemic conditions Erythroblastosis fetalis: It happens due to Rh incompatibility of blood in new born babies. Large amounts of hemosiderin pigment are released and discolor the dentin. Stain is usually green, brown or blue. Sickle cell anemia: It is an inherited blood dyscrasia. The discoloration is similar to erthroblastosis fetalis but more severe. Amelogenesis imperfect: It causes yellow to brown discoloration. Dentinogenesis imperfect: It causes brown, yellow or gray discoloration which should be treated by restorative procedures as composite buildup or crowns. Drug related defects There are certain drugs that when ingested the tooth color during its formation. a) Tetracycline In the 1960s Tetracycline was used to treat chronic obstructive diseases. It was discovered to discolor teeth in children. Color change ranges from light yellow to more darker gray to brown depending on the dosage, duration of intake and age of the patient at time of administration of the drug. Tetracycline binds to calcium and gets incorporated to hydroxyapatite crystals of enamel and dentin. Treatment may be bleaching extracoronally or intracoronally after intentional root canal therapy. b) Endemic fluorosis Intake of large amount of fluoride during tooth formation may produce defect in enamel matrix causing hypoplasia. It is seen as white spots ranging from chalky white to brown discoloration. Treatment is done by extracoronal bleaching with restorative therapy o the porous surface. c) Chlorhexidine This is a surface stain after prolonged use of chlorhexine mouthwash. It ranges from yellowish to brown color. Dentist related causes a) Endodontically related Pulp tissue remanants: If some pulp tissue remains in the pulp chamber especially the pulp horn, discoloration occurs due to tissue and blood decomposition. Intracanal medicaments: Phenolic or iodofrm based medicaments may discolor dentin. Obturating materials: After obturation, sealer and gutta percha have to be removed from the pulp chamber to prevent tooth discoloration. c) Restoration related Amalgam: Silver alloys with its tarnish may discolor the tooth structure which is difficult to treat. Pins and posts: Metal pins and posts may show through the composite restoration. Composite: Microleakage around a composite filling may discolor the tooth due to the entrance of bacteria and fluids through the gap between the tooth and the filling. Treatment is by replacing the filling. Bleaching Materials The main bleaching materials used now are: Hydrogen peroxide: It is also called Superoxol (30-35%) is the most common bleaching agent. It has a strong bleaching action but it is caustic and burns tissue in contact. Sodium perborate: It is a material that when dry is stable but in the presence of water it decomposes to form sodium metaborate, hydrogen peroxide and oxygen. It is safe and easily controlled so it is used in intracoronal bleaching. Carbamide peroxide: It is also called urea hydrogen peroxide (3-45%). It is mostly used in 10% and when it breaks down it forms about 3.5% hydrogen peroxide and many by-products as urea, ammonia carbon dioxide. Mechanism of bleaching action Bleaching agents act on the organic structure of the dental hard tissues, slowly degrading them to by-products as carbon dioxide. Inorganic molecules do not react with the bleaching agents. This reaction is called oxidation-reduction reaction or redox reaction whereby unstable peroxides convert to unstable free radicals which oxides or reduce other molecules. Bleaching techniques for endodontically treated teeth Thermocatalytic technique Isolate the tooth with rubber dam. Place bleaching agent (H2O2 or sodium peroxide or both) in the tooth chamber. Heat the agent with heat by a heat source (hot stick or light source). Repeat until bleaching gives satisfactory results. Wash the pulp chamber with water and seal the tooth with cotton pellet and temporary material. After 2-3 weeks, recall the patient to analyze the bleaching results. Place suitable filling material to seal permanently the tooth. Intracoronal/walking bleaching technique Take a radiograph to ensure good endodontic oturation. Isolate the tooth with rubber dam. Prepare an access opening and cleaning the pulp chamber from any gutta percha or filling material. Place a barrier as glass ionomer cement of 2 mm thickness on the coronal orifice to protect the dentinal tubules from penetration of the bleaching agent. Place a freshly mixed sodium perborate/water mix in the pulp chamber. Place a temporary filling to seal the access opening. Recall the patient after 1-2 weeks and repeat the treatment when needed. After completion of bleaching, close the access opening with composite material. When discoloration is internal and external a combination treatment can be done by: a) Intracoronal bleaching and in-office bleaching (placing H2O2 on the facial surface and placing a heat source) b) Intracoronal bleaching and home bleaching using a night guard template and H2O2 gel. Effect of bleaching agents on the tooth and surrounding structures 1Tooth sensitivity This is mostly seen with in office technique/ H2O2 with heat. This may be due to penetration of the bleaching agent through enamel and dentin and junctions with restorations. 2Effect on enamel Bleaching agents decrease enamel hardness but fluoride application restores remineralization of enamel. 3Effect on pulp When the bleaching agent penetrates the enamel and dentin it will cause transient reduction in pulpal blood flow. 4Cervical resorption When using H2O2 of more than 30% concentration, external cervical resorption may occur. 5Effect on composite After bleaching, composite fillings may be affected by surface roughening of the restoration. Tensile strength is decreased and microleakage is more possible to occur.