BLEACHING.pptx

BLEACHING CONSERVATIVE TREATMENT OF DISCOLORED TEETH  Discolorations are classified as extrinsic or intrinsic.  Extrinsic stains are located on the outer surfaces of teeth, whereas intrinsic stains are internal.  The etiology and treatment of extrinsic and intrinsic stains are discuss...

BLEACHING CONSERVATIVE TREATMENT OF DISCOLORED TEETH  Discolorations are classified as extrinsic or intrinsic.  Extrinsic stains are located on the outer surfaces of teeth, whereas intrinsic stains are internal.  The etiology and treatment of extrinsic and intrinsic stains are discussed in the following sections. I. Extrinsic Discolourations  Etiology  Stains on the external surfaces of teeth (referred to as extrinsic discolorations) are common and may be the result of numerous factors.  In young patients, stains of almost any colour can be found and are usually more prominent in the cervical areas of teeth (Fig. 21.19). These stains may be related to remnants of Nasmyth membrane, poor oral hygiene, existing restorations, gingival bleeding, plaque accumulation, eating habits or the presence of chromogenic microorganisms.  In older patients, stains on the surfaces of teeth aremore likely to be brown, black, or grey and occur on areas adjacent to gingival tissue. Poor oral hygiene is a contributing factor, but coffee, tea and other types of chromogenic foods or medications can produce stains (even on plaque-free surfaces).  In Southeast Asia, some women traditionally dye their teeth with betel nut juice to match their hair and eyes as a sign of beauty.  Tobacco stains also are observed frequently. Existing restorations may be discolored for the same reasons II. Intrinsic Discolourations  Etiology  Intrinsic discolorations are caused by deeper (not superficial) internal stains or enamel defects and are more complex to treat than external discolorations.  Teeth with vital or nonvital pulps as well as endodontically treated teeth can be affected.  Vital teeth discolouration  The staining may be located in enamel or dentin. Discolourations restricted to dentin still may show through enamel.  Discolouration also may be localized or generalized, involving the entire tooth.  i. During tooth development  Vital teeth may be discolored at the time the crowns are forming and the abnormal condition usually involves several teeth. Causative factors include  hereditary disorders,  medications (particularly tetracycline preparations),  excess fluoride,  high fevers associated with early childhood illnesses and  other types of trauma.  ii. Tertracycline staining  Various preparations of the antibiotic drug tetracycline can cause the most distracting, generalized type of intrinsic discolouration.  Staining from tetracycline-type drugs most frequently occurs at an early age and is caused by ingestion of the drug concomitant with the development of permanent teeth.  iii. Fluorosis  The presence of excessive fluoride in drinking water and other sources at the time of teeth formation can result in another type of intrinsic stain called fluorosis.  The staining usually is generalized.  iv. Aging  the permeability of teeth usually allows the infusion (over time) of significant organic pigments (fromchromogenic foods, drinks and tobacco products) that produce a yellowing effect.  Additionally, caries, metallic restorations, corroded pins and leakage or secondary caries around existing restorations can result in various types of intrinsic discolouration  Nonvital teeth discolouration  Nonvital teeth also can become discoloured intrinsically.  These stains usually occur in individual teeth after eruption has taken place.  I. The pulp may become infected or degenerate as a result of trauma, deep caries or irritation from restorative procedures.  If these teeth are properly treated by endodontic therapy, they usually retain their normal colour.  If treatment is delayed, discolouration of the crown is more likely to occur.  II. Trauma resulting in calcific metamorphosis (i.e. Calcification of the pulp chamber, root canal or both) also can produce significant yellowing of the tooth.  This condition is extremely difficult to treat  Mild discolourations are best left untreated because no restorative material is as good as a healthy, natural tooth structure. Bleaching treatment  The lightening of the colour of a tooth through the application of a chemical agent to oxidize the organic pigmentation in the tooth is referred to as bleaching.  In keeping with the overall conservative philosophy of tooth restoration, consideration should be given first to bleaching anterior teeth when intrinsic discolourations are encountered.  Classification of bleaching treatments  I. Nonvital bleaching procedures:  i. In-office nonvital bleaching technique  ii. Walking bleach technique  II. Vital bleaching procedures:  i. In-office vital bleaching technique  ii. Dentist-prescribed, home-applied technique  Bleaching generally has an approximate lifespan of 1–3 years, although the change may be permanent in some situations.  With all bleaching techniques, a transitory decrease occurs in the potential bond strength of composite when it is applied to bleached enamel and dentin.  This reduction in bond strength results from residual oxygen or peroxide residue in the tooth that inhibits the setting of the bonding resin, precluding adequate resin tag formation in the etched enamel.  No loss of bond strength is noted if the composite restorative treatment is delayed at least 1 week after cessation of any bleaching. MECHANISM OF BLEACHING  I. Nonvital Bleaching Procedures  The primary indication for nonvital bleaching is to lighten discoloured teeth that have undergone endodontic therapy.  Discolouration may be a result of:  bleeding into dentin from trauma before root canal therapy,  degradation of pulp tissue left in the chamber after such therapy  or staining from restorative materials and cements placed in the tooth as a part of the endodontic treatment.  A. In-Office Nonvital Bleaching Technique  A more current technique uses 30%–35% hydrogen peroxide pastes or gels that require no heat. This technique is frequently the preferred in- office technique for bleaching nonvital teeth.  It is also recommended that the bleaching agent be applied in the coronal portion of the tooth incisal to the level of the periodontal ligament (not down into the root canal space) to prevent unwanted leakage of the bleaching agent through the lateral canals or canaliculi to the periodontal ligament.  B. Walking Bleach Technique  The walking bleach technique is an in-office bleaching procedure that does not require the use of heat and employs sodium perborate as the bleaching agent.  The bleaching process is slower and continues till the patient reports back for the subsequent appointment for assessment and cessation of the treatment (hence the name ‘walking bleach’)  (A) Nonvital discolouration of dentin.  (B) The access cavity preparation is modified and gutta-percha is removed apically to just below the cervical margin. The pulp horns are cleaned with a round bur.  (C) A protective sealing cement is placed over the gutta-percha, not extending above the cervical margin. A paste composed of sodium perborate and saline (mixed to the consistency of creamy paste) is placed. The incisal area is undercut to retain the temporary restoration.  (D) A temporary filling seals the access.  (E) A permanent restoration is placed when the desired bleaching effect has been achieved.  II. Vital Bleaching Procedures  Indications for Vital Bleaching  I. Teeth intrinsically discoloured because of ageing, trauma or certain medications.  II. External vital bleaching techniques are alternative treatment options for a failed, nonvital, walking bleach procedure.  V. Other indications for external bleaching include teeth that have been darkened by trauma but are still vital or teeth that have a poor endodontic prognosis because of the absence of a radiographically visible canal (i.e.calcific metamorphosis).  VI. Brown fluorosis stains also are often responsive to treatment.  A. In-Office Vital Bleaching Technique  Clinical Technique  Step 1: rubber dam isolation  Step 2: 30–35% hydrogen peroxide bleaching  Most products consist of paste or gel compositions that most commonly contain 30–35% hydrogen peroxide.  Other additives, such as metallic ion-producing materials or alkalinizing agents that can speed up the oxidation reaction, also are commonly found in these commercially available whitening products.  The dentist places the hydrogen peroxide-containing paste or gel on teeth. The patient is instructed to report any sensations of burning of the lips or gingiva that would indicate a leaking dam and the need to terminate treatment.  The use of a light to generate heat may accelerate the oxidation reaction of the hydrogen peroxide and expedite treatment through a thermocatalytic effect. PAC lights and high-output quartz halogen lights have been commonly used for this purpose.  Use of lights to heat the bleaching agent, however, causes a greater level of tooth dehydration.  Use of carbon dioxide laser to heat the bleaching mixture and accelerate the bleaching treatment has not been recommended, because of the potential for hard or soft tissue damage.  Step 3: duration of treatment  Bleaching treatments generally are rendered weekly for two to six treatments, with each treatment lasting 30–45 min.  Step 4: postoperative considerations  On completion of the treatment, the dentist rinses the patient’s teeth, removes the rubber dam or isolation medium and cautions the patient about postoperative sensitivity.  A nonsteroidal analgesic and anti-inflammatory drug may be administered if sensitivity is anticipated.  Advantages  I. This procedure is totally under the dentist’s control and the soft tissue can be generally protected from the process.  II. This technique has the potential for bleaching teeth more rapidly.  Disadvantages  I. Cost of the treatment  II. Unknown duration of the treatment  III. The unpredictable outcome  B. Dentist-Prescribed, Home-Applied Technique  Clinical Technique  Step 1: fabrication of vinyl custom nightguard  Step 2: evaluation of the custom nightguard  Step 3: carbamide peroxide bleaching  A 10%–15% carbamide peroxide bleaching material generally is recommended for this bleaching technique.  Carbamide peroxide degrades into 3% hydrogen peroxide (active ingredient) and 7% urea.  Step 4: clinical use of nightguard bleaching  The patient is instructed in the application of the bleaching gel or paste into the nightguard.  Advantages  I. The use of a lower concentration of peroxide (generally 10%–15% carbamide peroxide)  II. Ease of application  III. Minimal side effects  IV. Lower cost because of the reduced chair time required for treatment  Disadvantages  I. Reliance on patient compliance  II. Longer treatment time  III. The (unknown) potential for soft tissue changes with excessively extended use