Whitening the SingleD i s c o l o re d Too t hSo Ran Kwon, DDS, MS, PhD KEYWORDS Single discolored tooth Traumatic injury Bleaching techniques ComplicationsThe single discolored tooth can be a challenge in obtaining an esthetic outcome in theanterior region (Figs. 1–3). Treatment options can vary from restorative proceduressuch as crowns, veneers, or bonding to more conservative bleaching treatments.The long-term success of the treatment is dictated by proper diagnosis and treatmentplanning. The cause and severity of the discoloration has to be carefully evaluatedwhen planning for bleaching options. The vitality of the pulp, presence and absenceof symptoms, and periapical pathoses usually determine whether an external orinternal bleaching approach will be considered.THE INITIAL EXAMINATIONPatients presenting with a single discolored tooth should always be questioned aboutany history of traumatic injury to the tooth. Regardless of the status of the pulp,a former trauma might have caused bleeding into the dentinal tubules resulting in adark brown to black discoloration. The baseline color may be evaluated with theVITA Classical shade guide (VITA, Bad Sackingen, Germany) or the VITA Bleached-guide (VITA, Bad Sackingen, Germany). However, single discolored teeth usuallyare outside the range of commercial shade guides so that technology-based colormeasuring devices such as the VITA Easyshade Compact (VITA, Bad Sackingen,Germany), Spectroshade Micro (MHT, Verona, Italy), or CrystalEye (Olympus, Tokyo,Japan) may be used to obtain a more objective evaluation of the tooth color at baselineand accurate data on the color change before and after bleaching. Another importantconsideration when evaluating baseline tooth color is the color of the root and thethickness and level of the gingiva. The dentin in the root is different from the anatomiccrown, and does not bleach well if at all, regardless of whether internal or externalbleaching is attempted.1 Radiographs, vitality testing with ice and electric pulp testing,and transillumination are additional procedures that should be performed to assesswhether root canal treatment is indicated prior to bleaching (Figs. 4–6). The case included in this article has been presented at the 2nd Annual Meeting of the Society of Color and Appearance in Dentistry, September 24, 2010. Department of Operative Dentistry, College of Dentistry, University of Iowa, Iowa City, IA 52242-1001, USA E-mail address: email@example.com Dent Clin N Am 55 (2011) 229–239 doi:10.1016/j.cden.2011.01.001 dental.theclinics.com 0011-8532/11/$ – see front matter Ó 2011 Elsevier Inc. All rights reserved.
230 Kwon Fig. 1. Preoperative view of full smile of the patient. If the tooth is nonvital and there is absence of periapical radiolucency and symp- toms, endodontic treatment is usually not recommended. However, if the pulp canal is severely obliterated, performing endodontic treatment before the development of a periapical radiolucency may prevent difficulty and complications associated with these teeth, and also increase the success rate for teeth treated without periapical radiolucencies versus teeth treated with periapical radiolucencies.2 CAUSES OF DISCOLORATION The tooth can discolor from extravasations of blood components into the dentinal tubules associated with pulp extirpation or traumatic injury.3 The blood cells undergo hemolysis and release iron, which reacts with hydrogen sulfide, a metabolic by-product of bacteria, to form iron sulfide, which causes the gray staining of the tooth.4 Incomplete removal of pulpal debris, especially in the pulp horn area, is another cause of discoloration in a single root-filled tooth.5 Root-filling materials can also cause coronal discoloration.6 Bleaching can be effective in removing stains depending on the substance. However, discoloration caused by metallic ions cannot be removed by whitening treatments.7 If the pulp survives a traumatic injury, it can undergo pulp canal obliteration, also referred to as calcific metamorphosis. Calcific metamorphosis is characterized by rapid deposition of hard tissue beginning within the pulp chamber and continuing along the root canal space, resulting in a yellow to brown discoloration of the clinical crown. Studies indicate that 1% to 16% of calcific metamorphosis cases will eventually undergo pulp necrosis, so that it is advisable to manage cases demon- strating calcific metamorphosis through observation and periodic examination.8 Fig. 2. Frontal view of discolored left central incisor.
Whitening the Single Discolored Tooth 231Fig. 3. Lateral view of discolored left central incisor.BLEACHING MATERIALS FOR THE SINGLE DISCOLORED TOOTHBleaching of discolored teeth was first attempted on nonvital teeth with the use ofvarious bleaching materials including chlorinated lime, oxalic acid, sodium peroxide,sodium hypochlorite, and mixtures of 25% hydrogen peroxide in 75% ether(pyrozone).9 Hydrogen peroxide, the most commonly used bleaching material nowa-days, was reported by Harlan in 1885.10 Hydrogen peroxide was placed into the pulpcavity at chair-side and replaced periodically or activated with electric current,11 heat,Fig. 4. Periapical radiograph. Note the pulp canal obliteration state on the left centralincisor.
232 Kwon Fig. 5. Vitality testing with electric pulp testing exhibited a positive response. or light12–15 to speed up the bleaching process. The acceleration was assumed to follow the Q10 rule that for every 10 C increase in temperature, the reaction rate increases 2 times. The use of a mixture of sodium perborate and distilled water was described by Salvas16 and reconsidered by Spasser17 as the walking bleach tech- nique. This technique is still widely accepted, with various modifications in the bleach- ing agent placed in the chamber. Nutting and Poe18 used a mixture of sodium perborate and 30% hydrogen peroxide to speed up the process. Since the first publi- cation on night guard bleaching with the use of 10% carbamide peroxide,19 mixtures of sodium perborate and carbamide peroxide of different concentrations have been proposed.20,21 The use of carbamide peroxide in nonvital bleaching has also changed the delivery method whereby the bleaching agent is placed inside the chamber as well as the outside in a custom-fitted tray.22–24 The use of carbamide peroxide has been advocated because of its neutral pH and slow release of active ingredients. However, when 30% hydrogen peroxide is mixed with sodium perborate in a ratio of 2:1 (g/mL) the pH of the mixture is alkaline, which favors the effectiveness of the bleaching agent. So far there seems to be no agreement on which bleaching material is best, but it seems prudent to understand the chemistry of each bleaching agent and apply it cautiously to the proposed treatment technique. BLEACHING TECHNIQUES There are several bleaching techniques available for the single discolored tooth. The decision is mainly based on the vitality of the tooth and whether the treatment should be performed in the office or at home, or a combination of both. Fig. 6. Transillumination is used to evaluate existence of severe crack lines.
Whitening the Single Discolored Tooth 233Single-Tooth In-Office BleachingA single discolored tooth without any symptoms, no periapical pathosis, and a ques-tionable response to vitality testing is a good candidate for in-office bleaching withhighly concentrated hydrogen peroxide that is commonly used in power bleachingfor vital teeth.Treatment Sequence Evaluate the color with a shade guide or a color measurement device (Figs. 7 and 8). Clean the tooth with a slurry of pumice and rubber-cup. Isolate the tooth on the facial and lingual side with a resin barrier or rubber dam (Fig. 9). Apply highly concentrated bleaching agent on the facial and lingual. Place a precut linear low-density polyethylene wrap onto the bleaching agent to prevent evaporation of the bleaching agent and inadvertent contact with the patient’s soft tissue (Fig. 10).25 Activate the bleaching agent with light (optional). Remove bleaching agent after 40 to 60 minutes with a high suction tip or a small cotton pellet. Rinse and remove the resin barrier or rubber dam. Evaluate the tooth color and reappoint patient for several in-office bleaching sessions until the desired shade is obtained.Single-Tooth Tray BleachingThe indication for single-tooth tray bleaching is similar to single-tooth in-office bleach-ing. However, if the patient shows good cooperation and prefers to perform the treat-ment at home, tray bleaching is highly recommended.Treatment Sequence Take an alginate impression of the whole arch. Pour the impression with plaster and avoid any bubbles or defects. Trim the cast so that the occlusal surface is parallel to the base (Fig. 11). Use an Omnivacuum machine to fabricate a custom-fitted tray.Fig. 7. Color map of right central incisor.
234 Kwon Fig. 8. Color map of discolored left central incisor. Trim the tray in a straight pattern on the facial and lingual side. Mark the tooth to be bleached and scallop the facial and lingual side of the tray, only at the marked tooth area (Fig. 12). Disinfect the tray with a cleaning solution in an ultrasonic cleaner. Deliver the tray and home bleaching gel (10%–20% carbamide peroxide gel). Instruct the patient to place the bleaching gel only at the discolored tooth and wear the tray overnight. Reappoint the patient to evaluate the progress of the treatment. Evaluate the color of the tooth and the bleaching change relevant to the adjacent teeth (Figs. 13–15). Thermocatalytic Bleaching The thermocatalytic bleaching technique is one of the oldest forms of bleaching nonvital teeth in the office. However, the use of highly concentrated hydrogen peroxide in a liquid state requires utmost attention, and the use of heat has often been associated with the development of cervical root resorption. Consequently the performance of the thermocatalytic bleaching technique is decreasing. Fig. 9. Isolation of discolored tooth with a resin barrier (OpalDam, Ultradent Products Inc, South Jordan, UT, USA).
Whitening the Single Discolored Tooth 235Fig. 10. Placement of a 38% hydrogen peroxide gel (Opalescence Boost, Ultradent ProductInc, South Jordan, UT, USA) and a linear low-density polyethylene wrap.Walking Bleach TechniqueThe use of an intracoronal filling of sodium perborate combined with water orhydrogen peroxide continues until today, and has been shown to be a successfultreatment for bleaching nonvital teeth.26Treatment Sequence Evaluate the existing root canal filling on the radiograph. Isolate the tooth with a well-fitting rubber dam. Clean the pulp chamber and the pulp horns of any debris or pulpal remnants. Remove the gutta percha root canal filling material with a heated instrument or a low-speed small round burr to 2 mm below the cementoenamel junction. Place a cervical barrier of 2 mm thickness with glass-ionomer cement or flowable resin to prevent the leakage of hydrogen peroxide into the surrounding alveolar bone. Mix sodium perborate with water or hydrogen peroxide in a ratio of 2:1 (g/mL) to a thick mix. Place the mixture into the pulp chamber with an amalgam carrier or an applicator. Use a damp cotton pellet to remove excess material to allow space for the temporary filling material. Use Cavit or glass-ionomer cement as a temporary filling material to properly seal the access cavity.Fig. 11. Trimmed cast with reservoir placement on the left central incisor.
236 Kwon Fig. 12. The custom fitted tray is scalloped only on the single discolored tooth. Recall the patient after 3 to 5 days to evaluate the progress of the treatment, and repeat the walking bleach procedure 3 to 5 times until the color matches that of the adjacent teeth. The final composite restoration should be placed 2 to 3 weeks after the last walking bleach procedure to allow for the color to stabilize, and to allow for the recovery of bond strength to tooth structure that is usually compromised immediately after bleaching.27 Inside-Outside Closed Bleaching This technique comprises the combination of walking bleach and the single-tooth tray bleaching to speed up the bleaching process and to reduce multiple appointments in the office. Inside-Outside Open Bleaching The inside-outside open bleaching technique is indicated in patients with good coop- eration, because the bleaching agent has to be applied outside and inside within the pulp chamber. Fig. 13. Color map of left central incisor after bleaching.
Whitening the Single Discolored Tooth 237Fig. 14. Split-tooth image showing the difference of color change before and after bleach-ing, DE 5 7.34.Treatment Sequence Take an alginate impression of the whole arch and fabricate a custom-fitted tray as for a single-tooth tray bleaching. Evaluate the existing root canal filling and place a cervical barrier of 2 mm thickness. Instruct the patient to fill the custom-fitted tray of the marked tooth on the labial side and also fill the pulp chamber with 10% to 20% carbamide peroxide. The tray can be worn every day, overnight until the color of the discolored tooth matches that of adjacent teeth. Show the patient how to irrigate the open chamber when debris has accumu- lated inside the chamber. Place the final composite restoration 2 to 3 weeks after the last bleaching gel application.Fig. 15. Natural blend-in of color with adjacent teeth after combined in-office and single-tooth tray bleaching.
238 Kwon COMPLICATIONS Occurrence of external cervical root resorption has been linked to intracoronal bleach- ing using hydrogen peroxide. The exact mechanism is still unknown, but it is hypoth- esized that hydrogen peroxide penetrates into the alveolar bone, causing an inflammatory response.28 It has also been postulated that hydrogen peroxide dena- tures the collagen initiating a foreign body reaction,29 or decreases the pH resulting in increased osteoclastic activity.30 All theories are based on the microleakage of hydrogen peroxide into the surrounding alveolar bone. Therefore it seems essential to place a barrier in order to seal the patent dentinal tubules, especially in young patients with wide open tubules, to prevent the development of cervical root resorption. SUMMARY Bleaching is the most conservative, economical, and safe approach for treating a single discolored tooth. The bleaching technique employed should be based on the vitality of the tooth and the cooperation of the patient. Whenever the tooth is vital or exhibits calcific metamorphosis on radiographs, an external approach should be used. In a nonvital tooth with existing root canal fillings, the chamber can be used for the walking bleach technique or for the inside-outside bleaching technique. Caution should be exercised as to the time of the placement of the final composite resin restoration in the pulp chamber. Bonding to the enamel and dentin is affected immediately after bleaching, so that the final restoration should be placed 2 to 3 weeks after the last bleaching session. Failure to do so might affect the long-term color stability of the treated tooth. REFERENCES 1. Haywood VB, Diangelis AJ. Bleaching the single dark tooth. Inside Dent 2010; 6(September):42–52. 2. daCunho FM, deSouza IM, Monnerat J. Pulp canal obliteration subsequent to trauma: perforation management with MTA followed by canal localization and obturation. Brazilian J Dent Traumatology 2009;1(2):64–8. 3. Goldstein RE, Garber DA. Complete dental bleaching. Berlin: Quintessence; 1995. 4. Grossmann LI. Endodontic practice. 5th edition. Philadelphia: Lea and Febiger; 1960. 5. Brown G. Factors influencing successful bleaching of the discolored root-filled tooth. Oral Surg Oral Med Oral Pathol 1965;20:238–44. 6. Van der Burgt TP, Plaesschaert AJ. Tooth discoloration induced by dental materials. Oral Surg Oral Med Oral Pathol 1985;60:666–9. 7. Glockner K, Ebeleseder K. Indikationen und Grenzfaelle fuer das Bleichen von devitalen verfaerbten Frontzaehnen. Quintessenz 1993;44:519–27 [in German]. 8. Amir FA, Gutmann JL, Witherspoon DE. Calcific metamorphosis: a challenge in endodontic diagnosis and treatment. Quintessence Int 2001;32:447–55. 9. Attin T, Paque F, Ajam F, et al. Review of the current status of tooth whitening with the walking bleach technique. Int Endod J 2003;36:313–29. 10. Harlan AW. The removal of stains from teeth caused by administration of medical agents and the bleaching of a pulpless tooth. Am J Dent Sci 1884/1885;18:521. 11. Westlake A. Bleaching teeth by electricity. Am J Dent Sci 1895;29:101.
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