RESTORATIVERESTORATIVE DENTISTRY DENTISTRY

Managing Discoloured Non-Vital Teeth: The Inside/Outside Bleaching Technique

NEIL J. POYSER, M ARTIN G.D. KELLEHER AND PETER F.A. BRIGGS

Abstract: should be supported by appropriate The discoloured, non-vital anterior tooth is a common aesthetic concern for special investigations. A methodical many patients. It can have a profound effect on their self-esteem, interaction with approach will ensure that the chance of others and employability. Discoloured non-vital teeth are frequently compromised failure is reduced and that any owing to previous trauma, caries, endodontic therapy and failed restorations. Destructive invasive treatment options are likely to weaken the residual structure of consequence of possible failure is the tooth. This can reduce the prognosis and challenge the long-term viability of the minimal. Ideally, the treatment option tooth, thereby initiating further prosthetic predicaments. This paper discusses modern chosen should provide a predictable approaches to the treatment of discoloured teeth. The importance of preventing and result and be the most beneficial and eliminating the potential for discoloration will be highlighted. The paper will include a cost-effective one for the individual detailed technical account on the application of the inside/outside bleaching technique, patient. with several clinical examples. The most common cause of discoloration in non-vital teeth is the Dent Update 2004; 31: 204–214 presence of pulpal haemorrhagic Clinical Relevance: The inside/outside bleaching technique offers multiple products. The discoloration seen is benefits to patients and practitioners when considering the options for a discoloured thought to be due to the accumulation non-vital tooth. of the breakdown products of haemoglobin or other haematin molecules5 from the pulp, and commonly follows trauma. Discoloration can also be seen after he presence of an unsightly Noticeable discoloration of teeth can endodontic intervention. It has been T discoloured tooth may be of great be a physical handicap that impacts reported that 10% of patients are concern to some patients and lead them on a person’s self-image, self- unhappy with the appearance of their to seek professional dental advice and/or confidence, physical attractiveness tooth following root canal therapy.6 treatment. The aesthetic improvement of and employability.4 Patients frequently ask ‘Will my tooth a patient’s smile can have a profound go ‘black’ now that it has been root affect on the patient’s confidence and A number of techniques have been treated?’ Restorative materials may oral health,1,2 and an improvement in oral developed to manage the problem of a contribute to the discoloration. It is health can significantly contribute to single pulpless discoloured tooth. The known that a number of the materials total well-being.3 aim of this paper is to discuss inside/ used during endodontic therapy, such outside bleaching and to compare the as silver-containing sealants and merits and problems of different points, polyantibiotic pastes, eugenol Neil J. Poyser, BDS, MFDS RCS(Edin.), and phenolic compounds may cause Specialist Registrar in Restorative Dentistry, GKT techniques. Dental Institute of King’s College London, St darkening and staining of the root George’s and Mayday Hospitals, London, Martin dentine.7 The migration of tin ions from G.D. Kelleher,BDS, MSc, FDS RCPS(Glasg.), Diagnosis amalgam restorations may also Consultant in Restorative Dentistry, GKT Dental An accurate diagnosis allows the contribute to discoloration. In the Institute of King’s College London, Royal Surrey, majority of cases, it could be said that it Kent and Canterbury Hospitals and Peter F.A. formulation of the optimal treatment Briggs, BDS, MSc, MRD, FDS RCS(Eng.), plan. In order to establish the is inappropriate management, choice of Consultant in Restorative Dentistry, GKT Dental diagnosis, it is necessary to obtain a techniques, or the placement of Institute of King’s College London and St full history and perform a inappropriate materials that are George’s Hospitals, London. comprehensive clinical examination that responsible for the discoloration.

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tray. Design the tray so that there are ab palatal and labial reservoirs for the target tooth, and so that the tray over the adjacent teeth is cut back to avoid the placement of the bleaching gel onto the unaffected teeth (Figure 3). l Check the bleaching tray for comfort and fit.

Figure 1 (a). A non-vital root-filled central incisor tooth that has discoloured. (b) The tooth was whitened using the inside/outside bleaching. Endodontic Preparation l Remove the access cavity restoration to allow thorough cleaning of the whole pulp chamber THE INSIDE/OUTSIDE obturated with no evidence of (including the pulp horns) with BLEACHING TECHNIQUE periapical pathology. If in doubt, ultrasonic instrumentation. FOR MANAGING consider endodontic revision prior l Remove the coronal aspect of the DISCOLOURED ROOT- to commencing bleaching. gutta-percha root filling to 2–3 mm FILLED TEETH l Record the pre-operative shade. below the cemento-enamel junction. This technique was originally described l Assess patient compliance and This can be easily and safely carried in the American literature by Settembrini reliability in returning for closure of out with a heated plugger. This et al.8 and modification of the technique the access cavity. provides space for the placement of a was later described by Liebenberg.9 l Discuss the treatment options. protective barrier over the root filling. In essence, the bleaching gel is placed l Inform the patient that existing This barrier should prevent bacterial on the internal and external aspects of the restorations may not bleach and ingress around the root filling and discoloured root-filled tooth. The access post-bleaching they may appear prevent the percolation of hydrogen cavity is left open during treatment so different from the surrounding tooth peroxide into the periodontal tissues. that the 10% carbamide peroxide can be tissue. The patient should be warned Glass ionomer cement, zinc easily and regularly changed. A custom- of this and the fact that these phosphate or zinc polycarboxylate made bleaching tray keeps the bleaching restorations may require can be used for this seal (Figure 2h). agent in and around the tooth. replacement. A diagrammatical note l Ensure that the pulp chamber is free Discoloured root-filled teeth can be of those restorations should be of root-filling materials. successfully managed with the inside/ made and given to the patient. outside bleaching technique. The l Check whether the patient is allergic majority of cases can be successfully to peroxide or plastic. Patient Instructions managed using the technique described l Check whether the patient is l Insert the tip of the bleaching below and without the need for pre- pregnant or breast-feeding. syringe into the access cavity of bleaching endodontic revision (Figures l Provide the patient with verbal and each root-filled tooth and fill the 1a and b). If there is concern about the written instructions. cavity with the 10% carbamide endodontic status, revision of the root l Make contemporaneous notes peroxide. filling may be required prior to recording that the above has been l Load the appropriate reservoir within commencing the bleaching (Figures 2a-g). carried out the tray with a pea-sized amount of the 10% carbamide peroxide (Figure 2i). l Insert the tray over the teeth and Patient Selection and Pre- Accurate Diagnosis remove the excess gel as necessary operative Preparation l Know what you are attempting to with a finger, tissue or soft toothbrush. It should be noted that it is necessary to bleach as not all discoloured teeth Rinse gently and do not swallow. follow the standard 10% carbamide will be as amenable to the bleaching peroxide external night-guard bleaching technique as non-vital teeth (e.g. protocol: those with tetracycline staining or Bleaching Protocol amalgam migration). l The gel should be changed inside l Make and record the diagnosis. the tooth and within the tray every l Check the periapical status on two hours and the tray containing radiographs. Bleaching Tray the gel should be worn overnight. l Check that the root-filled tooth is l Take an alginate impression and l After the bleaching session the asymptomatic and satisfactorily construct an appropriate bleaching patient should clean the access

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Case Report This 18-year-old male was concerned about the appearance of his discoloured upper left central incisor. When the patient was 12 years of age the tooth suffered a subluxation injury, subsequently lost vitality and was root treated. This case report illustrates the management of this discoloured tooth utilizing the inside/outside bleaching technique. Prior to bleaching, endodontic revision was provided in this case as there was clinical and radiographic evidence of endodontic failure.

Figure 2. (a) Pre-operative labial view of /1. Note the blue-grey discoloration concentrated Figure 2. (b) Pre-operative palatal view of in the cervical two-thirds of the crown. /1. Note the discoloration around the margins Figure 2. (c) Pre-operative radiograph of /1. of the leaking composite restoration. There is evidence of a sub-optimal root canal filling and a 6mm diameter periapical radiolucency. Clinical examination revealed the presence of a firm and tender apical swelling in the buccal sulcus. A decision was made to perform endodontic revision prior to commencing the bleaching.

Figure 2. (d) Removal of the access cavity Figure 2. (f) The access cavity was modified restoration revealed a heavily contaminated Figure 2. (e) The contaminated gutta-percha in order to gain complete access to the pulp pulp chamber. Such an environment is not point was removed from the canal. Note the chamber, including the pulp horns. The conducive to the placement of well-bonded, acid- extent of contamination and debris. chamber and coronal aspect of the root canal etched composite restorations. This probably was meticulously debrided with ultrasonic accounted for the staining around the restorative instrumentation. The canal was irrigated with margins due to the microleakage as seen in copious amounts of 5% sodium hypochlorite Figure 2b. and re-prepared. The tooth was dressed with non-setting calcium hydroxide for a fortnight prior to definitive obturation with gutta-percha and canal sealer.

Figure 2. (g) Post-operative periapical radiograph of the definitive root canal obturation. Figure 2. (h) The excess gutta-percha was cut back to beyond the cemento-enamel junction (CEJ) and a polycarboxylate protective barrier was placed to seal the root canal filling.

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Figure 2. (j) At the two week review the tooth was asymptomatic and there was a marked improvement in the colour. The tooth was provisionally restored with zinc polycarboxylate Figure 2. (i) The patient was instructed on the use of the inside/outside cement. A week following cessation of bleaching bleaching technique. Bleaching agent is syringed into the palatal access cavity the tooth was definitively restored with a and also into the bleaching tray. composite restoration.

cavities out with a toothbrush or should not be placed for at least a hinder the penetration of the bleaching single-tufted brush. Injection of the week after cessation of the bleaching agent. Adequate extension of the viscous bleaching gel within the process. This ensures that the enamel bleaching tray at the cervical margins is cavity will naturally remove any is free of any residual oxygen that necessary to hold the bleaching agent food debris throughout the day. would otherwise lead to air inhibition in this area for sufficient time. l Unlike vital bleaching, there is no of the composite bond.10 Those cases that remain discoloured, limit to how many times the material l Following bleaching, the tooth may despite good patient compliance, are can be changed as the patient is appear more translucent than the commonly because of discoloration highly unlikely to experience adjacent teeth owing to the reduced that is not of pulpal origin. This may be sensitivity. The more often the volume of dentine within the root- observed in discoloured non-vital teeth agent is changed, the more rapidly treated tooth. The ‘body’ of the that have previously been restored with the bleaching will occur. tooth should be restored with a an amalgam restoration in the palatal restorative material with moderate access cavity. The bleaching agent will translucent properties (e.g. glass readily breakdown the discoloration Reassessment ionomer cement or dentine shades molecules that originate from the pulp, l The patient should be instructed to of composite resin). This will but metal ions that have migrated from cease the bleaching procedure provide the tooth with a body the amalgam into the adjacent tooth when he/she is happy with the colour and will greatly enhance the structure are more resistant. All of the degree of lightening. The patient final aesthetic result. old amalgam must be removed as should be reviewed at 2–3 days to otherwise it can produce a green tinge, reassess the degree of lightening but this tends to occur only and to avoid prolonged exposure of Causes of Failure to Bleach occasionally with prolonged the access cavities. Owing to the A frequent reason for failure of the bleaching.11 Bleaching should still be frequency at which the bleaching target tooth to lighten is poor patient considered as the initial treatment of agent can be changed, the desired compliance. Good patient selection choice as it may produce the desired result will usually be achieved should minimize this as a problem. aesthetic result in the patient’s rapidly (about 2–3 days). Failure by the patient to follow the perception. If not, the new lightened l On completion of bleaching, the instructions will lead to prolonged baseline colour will improve the pulp chamber should be cleaned out treatment time and the discoloration aesthetic predictability of veneers. thoroughly with ultrasonic may remain. Prolonged treatment will instrumentation and provisionally mean that the access cavity is open for restored with glass ionomer cement longer and it may be more appropriate THE OTHER BLEACHING or zinc polycarboxylate (Figure 2j). to consider other treatment options. TECHNIQUES FOR The presence of existing restorations, MANAGING THE the incomplete removal of an access DISCOLOURED NON-VITAL Definitive Restoration cavity restoration, or the insufficient TOOTH l The definitive composite restorations removal of the coronal gutta-percha will Many different non-vital bleaching

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with time.21 The more significant factors There appears to be no evidence in relating to enamel changes are a low pH the scientific literature reporting the of hydrogen peroxide,22 higher development of invasive cervical concentrations of carbamide peroxide23 resorption when only low and the bleaching system used.21,24 concentrations of hydrogen peroxide Of frequent concern to dentists is the (i.e. 3.5% released from 10% carbamide possible association between the peroxide) are used and when hydrogen bleaching of non-vital teeth and the peroxide is used without heat. induction of resorption. Resorption can It is highly unlikely that patients will Figure 3. A bleaching tray used with the inside/ occur following trauma to a tooth or experience the same degree of outside bleaching technique. The upper right teeth. The probability of developing sensitivity sometimes associated with central incisor is undergoing bleaching treatment. resorption, and the severity of the vital night-guard bleaching, as the target Note how the tray is cut back from the upper resorption, is related to the type of tooth is non-vital. However, it has been right lateral incisor to avoid bleaching to this tooth during treatment. injury, the force involved, whether the shown that patients can still experience tooth was displaced from its socket and gingival and tooth sensitivity when a in which direction. The cases in which bleaching tray is used with a placebo techniques have been described. The internal bleaching has been associated bleaching agent.29 The fit and extension ‘walking bleach’ technique was with invasive cervical resorption are of the tray should be checked as an ill- described in 1961 by Spasser.12 This invariably those cases where heat,25 fitting tray may cause sensitivity. technique involved placing a paste of light and very high concentrations of sodium perborate mixed with water into hydrogen peroxide (e.g 30%) have been the pulp chamber of a non-vital tooth used,26 together with a previous history THE BENEFITS COMPARED and sealing it in. Later, in 1967, Nutting of trauma.27 Even with a thermo-catalytic WITH THE OTHER and Poe13 described a similar technique technique and ‘walking bleach’ BLEACHING TECHNIQUES using a paste of sodium perborate procedures, the incidence of developing There is little scientific evidence reported mixed with hydrogen peroxide. Sodium invasive cervical resorption has been specifically on the inside/outside perborate mixed with water has been reported to be relatively low. Figures of bleaching technique or studies reported to be as effective as when it is 3.9%27 and 6.8%28 have been reported in comparing this method with the other combined with hydrogen peroxide.14,15 bleached non-vital teeth with no history bleaching techniques.30 The majority of Techniques incorporating the use of of trauma, and 2%25 and 7.4%27 in the literature relates to case studies. heat and/or light16 have also been bleached non-vital teeth with a history Further research, preferably from suggested. Home bleaching with 10% of trauma. randomized controlled clinical trials, is carbamide peroxide gel has been The concentration of hydrogen necessary to confirm scientifically that advocated.17 peroxide released when 10% carbamide this technique has distinct benefits over peroxide is used is significantly less other bleaching techniques. than with the peroxide agents used in It is easy to see the potential benefits CONCERNS ABOUT earlier techniques. Sodium perborate of using the inside/outside bleaching BLEACHING releases 10% of its volume as hydrogen technique for non-vital cases compared The main areas of concern with regards peroxide, i.e. usually about 7% with the external night-guard bleaching to bleaching are over any possible hydrogen peroxide. When sodium technique. The removal of the access toxicity, damage to the hard dental perborate is mixed with 6% hydrogen cavity restoration allows evaluation of tissues, tooth resorption and sensitivity. peroxide this produces 17.8% hydrogen the pulp chamber, as in many cases a A comprehensive appraisal of the peroxide and, if mixed with 12% substantial amount of contamination and literature relating to the safety and hydrogen peroxide, produces 25.6% discoloration may originate from the effectiveness of 10% carbamide peroxide hydrogen peroxide. Ten per cent coronal aspect of the tooth. Bleaching under the supervision of a dentist carbamide peroxide releases 3.5% agent will not penetrate restorative filling confirms that it is completely safe from hydrogen peroxide. This is less than half materials, so removal of the palatal the viewpoint of general toxicity, risk of the concentration of hydrogen peroxide restoration allows the bleaching agent to mutation and risk of carcinogenesis.4 released by sodium perborate alone. get to where it is needed. A greater There are conflicting reports in the Resorption has only been reported in surface area is bleached at a time as the literature as to whether 10% carbamide cases where the concentration of 30% agent is applied to the external and peroxide has a detrimental effect on the hydrogen peroxide has been used in internal aspects of the discoloured tooth. hard dental tissues. The evidence seems combination with heat. This The potential benefits over the to indicate that the effect on the surface concentration is nearly nine times walking bleach technique is that there is texture.18,19 and wear resistance19,20 of greater than 3.5% hydrogen peroxide no temporary access cavity restoration human enamel is minimal and reversible released by 10% carbamide peroxide. that has the potential to be lost from the

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individual patient. ab The options for managing the discoloured, pulpless, non-vital tooth can be summarized as follows:

l Monitor and Review. l Bleaching: 1. Inside/Outside Bleaching Technique with 10% carbamide Figure 4. (a) A vital central incisor tooth, with evidence of pulpal sclerosis, which has discoloured. peroxide. (b) The tooth was whitened using the external night-guard bleaching technique. The patient has 2. Walking Bleach Technique: a high lip line so masking the discoloration with other restorative techniques may have been less i. Carbamide peroxide; predictable. ii. Sodium perborate and water; iii. Sodium perborate and hydrogen peroxide. access cavity because of the oxygen for caries within 2–3 days. The presence 3. External Bleaching – Chairside liberated from the bleaching agent of a restoration to seal the gutta-percha Bleaching or Home Bleaching or trapped inside. The degradation rate of root filling, and the fact that the 10% a combination of both. carbamide peroxide during the bleaching carbamide peroxide is bactericidal itself, l Restorative: process is exponential and, after two will minimize the potential of coronal 1. Veneer – Direct composite or hours, only 50% of the active carbamide leakage and endodontic failure. Patients indirect laboratory constructed peroxide is still available.31 The efficacy may occasionally complain of food composite or porcelain veneers; of the bleaching process is maximized as packing in the access cavity. Patients 2. Crown – with or without a post; the carbamide peroxide can be changed with good manual skills may be 3. Extraction and prosthetic every two hours. instructed to place a cotton pellet within replacement. The use of 10% carbamide peroxide the access cavity in between bleaching without the application of heat is episodes and during eating. This must intended to reduce the potential for the then be removed prior to recommencing Monitor induction of cervical resorption that is bleaching. Some patients, especially with a low lip associated with other bleaching The external (only) night-guard line, may accept a mildly discoloured techniques. The treatment time is shorter bleaching technique could be used in tooth. However, monitoring of the than the walking bleach technique so the discoloured tooth cases where there is situation may be unacceptable to many contact time of the hydrogen peroxide concern about contamination of the patients. The presence of discoloration with the peri-cemental tissues is reduced. access cavity restoration or for ‘topping may indicate that restorative failure has The concentration of released hydrogen up’ the lightened non-vital tooth in the occurred (e.g. owing to endodontic or peroxide is lower than that used with the future. However, this is not as effective restorative leakage), and suggest that walking bleach technique or the as the inside/outside bleaching appropriate intervention is necessary. thermocatalytic technique. As the technique. bleaching is carried out at home, the In cases where a localized discoloured patient is very much responsible for the tooth is vital (e.g. pulpal obliteration or Restorative degree of lightening they want for their contusion injuries) there is no need to Placement of a veneer on a significantly tooth. root treat the tooth electively (Figure 4) discoloured single tooth is unlikely to The potential disadvantage of this and standard external night-guard provide a satisfactory aesthetic result. technique is that good patient bleaching can be used in these cases.32 The cervical margin is the most difficult compliance is necessary. The patient area to mask and this may be of most must be relatively dextrous to place the concern in an aesthetically driven bleaching agent within his/her tooth. DISCUSSION OF THE OTHER patient with a high lip line. In order to The access cavity must remain open TREATMENT OPTIONS mask the discoloration, it may be during treatment but this should not be There are many treatment options and necessary to construct a relatively thick of concern when this technique is used combinations of options available to veneer with an initial opaque layer.33 for a short period of time in a motivated manage the discoloured tooth. The This involves greater cervical tooth patient. As long as the patient is caries protracted problems associated with the preparation in order to provide an free, aware of his/her diet, and capable regulations of bleaching products in the adequate bulk of porcelain in this region of using a single-tufted brush or probe UK has contributed to the clinical and and to prevent a poor emergence profile. to clean the cavity, one should not be ethical dilemmas in deciding which The enamel is relatively thin at the overly concerned about any potential option is the most appropriate for an cervical margin, so any tooth reduction

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in this region is likely to expose a long-term clinical or aesthetic outcome. meticulous approach will help to prevent significant amount of discoloured Restorations used to mask the and minimize problems in the future. dentine and may make the situation discoloration do not address the worse. It is difficult to harmonize a thick, remaining discoloration within the root l Optimal management and follow-up possibly opaque, veneer on a dentine. Gingival recession in the future of trauma cases – to help ensure discoloured tooth with an adjacent may lead to the exposure of the that pulpal health is maintained. To natural tooth that has different restorative margins and the discoloured instigate endodontic therapy as translucent, reflective and refractory root dentine. The completion of gingival soon as necessary in order to properties. Porcelain veneers have a maturation around the crown of an minimize the possibility of relatively good survival rate with a adolescent patient may result in a similar discoloration from the dying pulp. failure rate of approximately 3% per predicament. There is the potential for the l Adequate access – in order to gain year.34,35 However, once a patient has greyness of a metallic post to shine good access to the pulp canal embarked on restorative treatment, the through the cervical aspect of the tooth system. Ensuring that no pulpal tooth is likely to be involved in further and cause cervical ‘grey-out’. In order to remnants are left in the pulp horns of preparation and restorations. Despite improve the aesthetics, it may be the chamber. the reported favourable survival rate of necessary to replace the restoration and l Ultrasonic instrumentation - to veneers, it is appropriate to note that extend the restorative margins more ensure complete debridement of the ‘survival’ does not necessarily relate to cervically. The conical form of a root pulp chamber, especially the pulp ‘aesthetic satisfaction’. Many reports means that further tooth preparation in a horns. Entry into the pulp chamber do not include this important cervical direction will be on a smaller with an ultrasonic tip permits safer information, in spite of the fact that circumference of root. In order to produce canal localization, with less chance many veneers are placed to improve the a suitable preparation form, it is of perforation when compared with appearance. necessary to remove an increasing rotary instruments. It has been reported that the amount of precious coronal tooth tissue. l Copious irrigation – sodium preparation and impression standards This will result in an increased crown-to- hypochlorite is the irrigant of choice. for veneers provided within the UK are root ratio and a reduced bulk of root Its bactericidal and tissue-degrading less than satisfactory.36 This lack of dentine. It must be remembered that there properties ensure that pulpal predictability has been suggested as a is the potential for gingival recession to remnants are removed as far as reason for the reduction in the number of occur again in the future. possible from the root canal system. porcelain veneers prescribed in England The profession also accepts that Owing to the complexity of the root and Wales. In the year 1992–93, a total of dental restorations do fail and are canal system, a chemo-mechanical approximately 150,500 porcelain veneers increasingly communicating this to approach is necessary to maximize were claimed under the NHS General patients from the outset. It is likely that the efficiency of canal debridement. Dental Service in England and Wales. numerous replacements of restorations l Good endodontic preparation and This figure steadily reduced over the next will be required in a young/middle-aged obturation techniques – to minimize decade by nearly 50% to 83,000 in the patient’s lifetime. The more conservative coronal or apical leakage. year 2001–02.37 The concern is that, the technique used at the start, the more l Adequate coronal gutta-percha because of the real and imagined options will be available if and when removal – to avoid discoloration of difficulties with veneers, practitioners failure occurs later in life. A more the tooth owing to shine-through of may be prescribing more destructive conservative approach utilizing bleaching the gutta-percha and to allow techniques, such as full coverage techniques and/or adhesive principles adequate penetration of the restorations, as they may feel that these will often produce a very satisfactory bleaching agent to the cervical are more predictable, easier in terms of outcome and also ensure that sufficient margin. Removal of the carbon aesthetic ‘blending’, and possibly better tooth structure remains for any deposits of the heated and burnt financially compensated under the NHS subsequent restorations. gutta-percha with ultrasonic General Dental Services. instrumentation is necessary. The dental profession is slowly Adequate reduction also allows for accepting that the destructive restorative PREVENTION OF TOOTH an optimal height of the coronal procedures, involved in the placement of DISCOLORATION access restoration to be placed and full coverage restorations, have Ideally, one should attempt to prevent the minimizes possible microleakage. significant biological consequences and discoloration from the outset, as l Suitable access cavity restorative problems. The placement of a full prevention is better than cure. The materials – amalgam is unsuitable as coverage restoration in an attempt to practitioner has multiple opportunities this can lead to discoloration. A well- provide a predicable and ‘permanent’ during the management of a potentially placed tooth-coloured material such solution for the discoloured tooth may discoloured non-vital tooth to prevent as composite is the restoration of not provide a favourable ‘permanent’ this occurring. A systematic and choice. An optimal technique for

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placement is required in order to are the retention of precious tooth tissue 20: 986–991. 17. Frazier KB. Nightguard bleaching to lighten a avoid microleakage, discoloration and avoiding the risks associated with restored, non vital discoloured tooth. Compend and loss of the restoration, tooth preparation and post preparation. Contin Educ Dent 1988; 19: 810–813. secondary caries or endodontic The technique is very cost-effective 18. Haywood VB, Leech T, Heymann HO, Crumpler D, failure when compared with invasive restorative Bruggers K. Nightguard bleaching: effects on enamel l surface texture and diffusion. Quintessence Int 1990; Monitoring and regular review – so procedures, especially when laboratory 21: 801–804. that intervention can be instigated fees have to be considered. If, for any 19. Lopes GC, Bonissoni L, Baratieri LN, Vieira LC, as soon as needed. reason, the bleaching fails to provide the Monteiro S Jr. Effect of bleaching agents on the final desired result, the new baseline hardness and morphology of enamel. J Esthet Restor Dent 2002; 14(1): 24–30. colour can facilitate the success of less 20. Clelland NL, Dorosti Y, Seghi RR. Effect of DISCUSSION aggressive adhesive techniques such as carbamide peroxides on wear resistance and color There are many options for managing veneers. change of enamel opposing porcelain. discoloured teeth. However, there is a J Prosthodont 2002; 11: 81–85. 21. Turkun M, Sevgican F, Pehlivan Y, Aktener BO. marked contrast in the amount of tooth Effects of 10% carbamide peroxide on the enamel structure that has to be removed to surface morphology: a scanning electron provide a similar aesthetic outcome. The REFERENCES microscopy study. J Esthetic Rest Dent 2002; 14: 1. Baldwin DC. 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