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Cosmetic dentistry has become a very importantpart of restorative dental practice. The appearance

and color of teeth are important to many individualsseeking dental treatment. Studies in the 1980s1 and1990s2,3 already demonstrated that at least one-thirdof the population is not satisfied with the color andform of their natural teeth. It has been estimated thatamong patients presenting for cosmetic treatments, upto 15% suffer from a psychiatric condition termedBody Dysmorphic Disorder (BDD) also known as dys-morphophobia, literally meaning “fear of ugliness”.4,5

BDD has an estimated prevalence of 1% to 2% in thegeneral population and is characterized by a preoccu-pation with a slight or imagined defect of some aspectof physical appearance.6-8 Patients with such preoccu-pation were nine times more likely to consider toothwhitening.9 With the increasing demand for estheticdental care, it is clear that bleaching can present a mini-mally invasive cosmetic approach.

The effect of external bleaching agents on dental hardtissues has been extensively investigated. Systematic re-

views demonstrated that bleaching treatments mighthave a deleterious impact on restorative materials andrestorations, and that external bleaching with heat mustbe done with caution due to unknown effects on the pul-pal tissue.10 It was also shown that bleaching agentsmight have a negative influence on the integrity of or-ganic enamel structures;11 in addition, mineral loss, lossof fluoride, increased susceptibility to erosion or caries,increased surface roughness, reduced enamel microten-sile strength, reduced fracture stability, and a decrease inabrasion resistance of bleached dental hard tissues werealso seen.12 On the other hand, at present no clinicalstudies or case reports in the literature have docu-mented macroscopically or clinically visible damage dueto vital bleaching or clinically relevant tissue destruction.

Vital tooth bleaching is a popular treatment modalityin dentistry. In order to enhance or to accelerate thewhitening process, heat activation of the bleaching agentby light, heat, or laser has been introduced. Some pro-ponents of “power bleaching” with light also claim thatthere is an improved light absorption, a reduced tooth

Laser-assisted Bleaching with the KTP Laser

Katrien Vanderstrichta, Roeland J. G. De Moorb

a Clinical Resident, Department of Operative Dentistry and Endodontology, Ghent University, Ghent University Dental School, Gent, Belgium.

b Professor, Department of Operative Dentistry and Endodontology, Ghent University, Ghent UniversityDental School, Gent, Belgium.

Abstract: At present, the only system providing laser bleaching (of stains on and in tooth substance) with pho-tothermal, photochemical, and photocatalytic activation of the bleaching gel is the combined use of the KTPlaser (λ = 532 nm) with the Smart Bleach gel (SBI). Moreover, this system offers the advantage of performingtrue photobleaching, meaning that the problem of persisting intense discoloration resistant to the action of theoxygen free radicals – such as results from tetracyclines –can be solved.

Keywords: laser bleaching, KTP laser, photobleaching, power bleaching, tetracyclines.

J Oral Laser Applications 2009; 9: 129-136.

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heating, and even a photochemical activation of thebleaching gel thanks to the addition of an activator orcolorant.13 In a systematic review, Buchalla and Attin10

concluded (1) that available studies on power bleachingdid not allow for a final judgement on whether toothwhitening could be increased or accelerated by addi-tional activation; (2) that activation of bleaching agentsby heat, light, or laser may have an adverse effect onpulpal tissue due to an increase of intrapulpal tempera-ture exceeding the critical value of 5.5°C; (3) that thereis no real evidence of photochemical bleaching, andpower bleaching is the result of photothermal activation.

KTP LASER BLEACHING

The review by Buchalla and Attin10 was performed be-fore the availability of studies in A1 journals using KTPlaser (λ = 532 nm) (green light) for dental bleaching. Anumber of recent studies have demonstrated that KTPlaser bleaching (1) did not result in changes or resultedin signif icantly less change in microhardness of thebleached enamel,14,15 (2) did not result in damaging tem-perature elevation,16,17 (3) was effective at providingbrighter teeth than with diode laser and LED,15 and (4)was particularly helpful for whitening of tetracyclinestains.18-20

KTP laser (High Tech Laser; Herzele, Belgium) bleach-ing with the Smart Bleach gel (SBI; Herzele, Belgium)differs from other light activated systems: of particularinterest is the red color of the bleaching gel (red andgreen are complementary colors) and the specific wave-length of 532 nm which can break tetracycline moleculesand greyish discolorations into colorless molecules. Thissystem is rather new and was patented in 2000.21 Thehydrogen peroxide based bleaching gel (50% H2O2) ismixed with a photosensitizer, rhodamine B dye, resultingin an aqueous gel of high pH (pH 9.5). The activation ofthe alkaline gel results in the release of hydroxyl andother oxygen free radicals, which can break down vari-ous colored organic molecules. Under these conditions(intense light and alkaline pH), hydroxyl radicals are pro-duced by decomposition of the hydrogen peroxide.These radicals are more reactive than superoxide andother oxygen reactive species.22 Thus, the activation ofthe red bleaching gel with the KTP laser under alkalineconditions will result in a photocatalytic effect (limitedphotothermal activation of the gel and more pro-nounced photochemical activation). This process is anexample of a photodynamic process employing intenselight from a noncoherent light source of a laser to drivea sequence of molecular changes in light-sensitive com-

pounds, which results in the generation of reactive oxy-gen species. In the Smart Bleach system, photodynamicreactions are exploited for the purpose of bleachingteeth. Activation of the gel results in the release of hy-droxyl and other oxygen free radicals. In an alkaline en-vironment (here, ionization of buffered hydrogenperoxide) more perhydroxyl ions are released, of whichis known that they are 50% more reactive than otheroxygen molecules.

Next to the photocatalytic effect, there is also thefeasibility of photobleaching thanks to the specific wave-length. The KTP laser is capable of photo-oxidizing thechelate formed between tetracyclines and hydroxyap-atite or calcium orthophosphate, and not responding tothe chemical bleaching agents, eg, the produced freeradicals. Most grey discolorations form the same chelateas tetracyclines with hydroxyapatite or calcium ortho-phosphate. These complexes are also photo-oxidizableby the 532 nm of a KTP laser. The combination of allthese characteristics enables a more profound bleachingof teeth as compared to other bleaching systems.

THE SMART BLEACH PROCEDURE

The appointment for laser bleaching is approximately 90min in duration, including the initial preparation andphotographs. Before the start of the bleaching appoint-ment, all patients had an initial appointment where theoral health status was screened. Contraindications forbleaching are leaking restorations, periodontal prob-lems, caries, too many sensitive root necks, and enamelfractures or cracks. Patients are also informed that theyhave to stop smoking. Bleaching is not performed inmouths without sufficient oral hygiene, with periodontalproblems and untreated carious lesions. Before the start of the bleaching procedure, patients at the GDLC(Ghent Dental Laser Centre) also sign an informed con-sent form, which informs them about the following:what hydrogen peroxide is and its possible side effects,the bleaching procedure, the fact that in a number ofcases more than one session will be needed to achieve agood result and that it is difficult to predict results in ad-vance, the impact of pigments on tooth discolorationand the impact of these colorants on the result and themaintenance of the bleaching result, the fact that fillingmaterials and porcelain cannot be bleached, that a re-lapse as a function of time due to aging is possible, andthat photographs and the patients’ background can beused anonymously for research purposes.

At first, extrinsic stains, plaque, debris, and/or de-posits of pellicle are removed with pumice in order to

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obtain optimal results (Fig 1). Any remaining organicproteinaceous material on the tooth surface will interactwith the bleaching agent, and also reduce its penetrationinto the enamel, reducing its effectiveness. Conventionalpolishing and prophylaxis pastes may not be used, be-cause they contain oils and coat the tooth surface, thusinhibiting the redox reaction and impairing the genera-tion of free radicals.

A cheek retractor is then placed and teeth are gentlydried, followed by taking photographs. When using theOptraGate Lip and Cheek Retractor (Ivoclar Vivadent;Schaan, Liechtenstein), the retractor is placed at the be-ginning of the procedure (Fig 2). Both extremes in theshade guide (VITA B1 and C4) are included in the firstimage (Fig 3). A second photograph is taken with theshade guides reproducing the color of the teeth (Fig 4).

At present we prefer to use the OptraGate Lip andCheek Retractor. Lips and cheeks are more gently and

evenly retracted than with conventional retractors. Thesystem is also more comfortable for the patient and pro-tects the lips better against contact with the bleachinggel. This is also important because the patient must re-main still for a good part of the procedure. A combina-tion bite block and saliva aspirator (the “expanded dutycotton mouth dry field system”, HighTech Laser) is alsoused (Figs 5 and 6). This block protects the tongue fromcontact with the bleaching materials. Being able to biteon this block also helps the patient relax and enables po-sitioning of the mandible and maxilla, facilitating thebleaching procedure. The isolation devices must remainin position and the patient is not permitted to rinse.

After drying teeth and gums using compressed air, agingival protection is applied. Exposed cervical root sur-faces and the cervical gingival tissues are protected fromthe hydrogen peroxide gel and from dehydration, usinga flowable resin material (Smartblock). Soft tissues need

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Fig 1 Cleaning of the teeth with pumice. Fig 2 Rinsing and gentle drying of the teeth.

Fig 4 Second photograph with shade guides reproducing thecolor of the teeth.

Fig 3 Situation before treatment with extremes in the shadeguide (VITA B1 and C4).

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to be protected, as they would absorb the visible greenlight of the KTP laser, resulting in thermal damage. TheSmartblock is applied using a syringe with a blunt tipwhich is placed directly into the opening of the gingivalcrevice (Fig 7). The flowable resin is applied in layers,with the first layer covering the cervical aspects of theteeth for approximately 1 mm. After placement of aborder 2 cm long (the width of 2 teeth), the resin isphotopolymerized (Figs 8 and 9). The flowable compos-ite can also be used for the protection of areas of ex-posed dentin on the root surface or the crown.

The patient, assistant, and dentist performing thelaser whitening procedure must wear protective glasses,because the human eye is extremely sensitive to visiblegreen light. Appropriate protective glasses, goggles orface shields must have an attenuating power of log 4(OD 4).18 A vitamin E gel is also delivered with the sys-tem, and can be used for instant neutralization of tissueirritation or burning due to contact with the bleachinggel. This gel is a very strong anti-oxidant.

The SmartBleach gel needs to be prepared in ad-vance. About 5 ml of peroxide is mixed with the powderto give the desired gel consistency. Once mixed, the gelmust be allowed to stand in its closed container for atleast 5 min to allow the carbonate buffer system withinthe gel to elevate the pH to approximately 9.5. TheSmartBleach gel is colored using rhodamine B dye,which absorbs visible green laser light and breaks downto release oxygen free radicals.

The gel is applied in thin layers on the teeth with aspatula or a brush and in a predetermined sequence. Be-cause maxillary teeth are bigger and have a thicker layerof enamel, especially in the front area, the gel is appliedfirst on the central incisors 11-21, followed by 12-22, 13-23, 14-24, 15-25, 41-31, 42-32,43-34, 44-35, 45-35.

Every tooth is irradiated for 30 s in the same se-quence as the gel application (Fig 10). The laser beam isapplied with a spot size of 6 to 8 mm, using continuouswave. The handpiece is moved in a sweeping actionacross the tooth surface at a power of approximately 1W. If unfavorable or unacceptable sensitivity occurs, en-ergy density or the average power setting has to be de-creased. After irradiation, the gel is left for 10 min onthe teeth. Activation and exposure of the gel to the laserbeam results in discoloration of the red gel (Fig 11).Therefore, it is also important not to apply the gel toothickly.

After completion of one pass over all teeth, the gel isthen removed by aspiration and the teeth are thor-oughly rinsed with spray. After inspection of the effectand result, the teeth are gently dried, fresh gel is appliedif needed, and the whole procedure is repeated. A maxi-mum of four passes can be performed in one treatmentsession.

Selective application to restricted areas on a singletooth (eg, tetracycline bands) or teeth is also possible.Instead of the handpiece, a fiber can be used for the acti-vation of the gel for bleaching of localized discolorations

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Fig 6 Protection appliances in situ (cheek retractor – bite blockwith connected saliva aspirator).

Fig 5 The expanded duty cotton mouth dry field system.

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or bands. The fiber is also moved with a sweeping actionover the area covered with gel for 30 s at a power of 1W. At present, investigations have shown that a 10-spass at 3 W also results in successful whitening and canbe of interest for intense discolorations.17

After the last pass is complete and the teeth arecleaned of gel remnants, the gingival protection is re-moved. After wetting of the teeth with water spray andgentle drying as done in the beginning of the procedure,the final shade can be checked using shade tabs. The twocalibrator shades (VITA B1 – C4) (Fig 12) and the origi-nal shades (Fig 13) are included in the image to act asreference points.

When the bleaching procedure is completed, a trans-parent neutral sodium fluoride gel is applied to theteeth. The cheek retractors are removed and the resultis discussed with the patient. Patients are also instructednot to consume pigmented foods for 72 h. Coffee, tea,red wine, and smoking should be avoided. An appoint-

ment is always made for a control session after 2 weeks.If more than one bleaching appointment is needed, theinterval is one month.

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Fig 9 The gingival block protects the gingival margin and covers 1mm of the tooth at the cervix; this important to ensure that theresin is inserted into the sulcus.

Fig 10 Activation of the gel.

Fig 8 Photopolymerization of the Smartblock.Fig 7 Application of the gingival protection.

Fig 11 Result of the pass over the gel with the laser.

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CLINICAL CASES

A guideline to predict a possible outcome of a KTP laser-assisted bleaching is shown in Table 1. Satisfactory re-sults are obtained for mild to moderate yellowdiscolorations after two to three applications of thebleaching gel; intense discolorations regularly requirefour passes (Figs 14 to 17). Figures 18 to 20 give an ex-ample of a case where the patient was not satisfied withhome bleaching using trays. After cleaning with pumice,there was already some change of the color, though withlaser bleaching it was possible to eliminate the yellowand orange discoloration. Brown discolorations aremore resistant to whitening and generally require at

least three passes of bleaching gel and laser energy.Whitening of intense grey discolorations as well as tetra-cycline staining degrees II and III is hardly possible with-out the application of laser energy. Here, it is alwaysimportant to temper the patients expectations and em-phasize that at least two sessions are mandatory (Figs 21and 22).

REFERENCES

1. Goldstein RE. Survey of patient attitudes toward current estheticprocedures. J Prosthet Dent 1984;52:775-780.

2. Truin GJ, Burgersdijk RC, Kalsbeek H, van ‘t Hof MA. Cosmeticdentistry. Ned Tijdschr Tandheelkd 1989;96:378-381.

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Fig 13 Result with color shade close to the bleached teeth.Fig 12 Result with color comparison (extremes of the colorshades).

Table 1 Effectiveness and number of treatment sessions (according to Ver-heyen et al23)

Discoloration 1 treatment session 2 treatment sessions 3 treatment sessions

Yellow mild Xmoderate X (X)intense X

Brown mild Xmoderate X (X)intense (X) X

Gray mild X (X)moderate (X) Xintense X (X)

Tetracycline grade I X (X)Tetracycline grade II X (X)Tetracycline grade III (X) X

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3. Willemsen WL, Burgersdijk RC, Truin GJ, Mulder J. Cosmeticdental treatment in an adult Dutch population. Community DentHealth 1994;11:156-160.

4. Sarwer DB, Wadden TA, Pertschuk MJ, Whitaker LA. Bodyimage dissatisfaction and body dysmorphic disorder in 100 cos-metic surgery patients. Past Reconstr Surg 1998;101:1644-1649.

5. Crerand CE, Franklin ME, Sarwer DB. Body dysmorphic disorderand cosmetic surgery. Plast Reconstr Surg 2006;118:167-180.

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Fig 19 Cleaning with pumice already reveals a lighter color,though there are still yellowish and orange discolorations present.

Fig 16 Before KTP laser bleaching.

Fig 15 After laser bleaching.

Fig 17 After KTP laser bleaching.

Fig 14 Before treatment.

Fig 18 Patient was not satisfied after a home bleaching with trays.

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6. Oosthuizen P, Lambert T, Castle DJ. Dysmorphic concern: preva-lence and association with clinical variables. Aust NZJ Psychiatry1998;32:171-179.

7. Corove MB, Gleaves DH. Body dysmorphic disorder: a review ofconceptualizations, assessment, and treatment strategies. ClinPsychol Rev 2001;21:949-970.

8. Rief W, Buhlmann U, Wilhelm S, Borkenhagen A, Brahler E. Theprevalence of body dysmorphic disorder: a population based sur-vey. Psychol Med 2006;36:877-885.

9. De Jongh A, Oosterink FMD, van Rood YR, Aartman IHA. Pre-occupation with one’s appearance: a motivating factor for cos-metic dental treatment? Br Dent J 2008;204:691-695.

10. Buchalla W, Attin T. External bleaching therapy with activation byheat, light or laser – a systematic review. Dent Mater 2007;23:586-596.

11. Attin T, Schmidlin PR, Wegehaupt F, Wiegand A. Influence ofstudy design on the impact of bleaching agents on dental enamelmicrohardness: a review. Dent Mater 2009;25:143-157.

12. Hegedüs C, Bistey T, Flora-Nagy E, Keszthelyi G, Jenei A. Anatomic force microscopy study on the effect of bleaching agentson enamel surface. J Dent 1999;27:509-515.

13. Baik JW, Rueggeberg FA, Liewehr FR. Effect of light-enhancedbleaching on in vitro surface and intrapulpal temperature rise. JEsthet Restor Dent 2001;13:370-378.

14. De Moor RJG, Vanderstricht K. KMO Innovation Project –Province of Eastern Flanders / Belgium – The influence of bleach-ing agents of two in-office bleaching systems and the SmartBleach system (KTP laser-activated bleaching) on enamel micro-hardness. 2007.

15. Zhang C, , Wang X, Kinoshita JI, Zhao B, Toko T, Kimura Y, Mat-sumoto K. Effects of KTP laser irradiation, diode laser, and LEDon tooth bleaching: a comparative study. Photomed Laser Surg2007;25:91-95.

16. Walsh LJ, Liu JY. Digital image analysis of changes in tooth shadewith laser photochemical and photothermal bleaching. ESOLA(European Society for Oral Applications), 2nd Laser Congress,Florence, Italy 2003.

17. De Moor RJG, Vanderstricht K. KTP Laser bleaching. NationalBelgian Laser Symposium, Gent, Belgium. January 30, 2009.

18. Walsh LJ, Liu JY, Verheyen P. Tooth discolouration and its treat-ment using KTP laser-assisted tooth whitening. J Oral Laser Ap-plic 2004;4:7-21.

19. Vanderstricht K, De Moor RJG. Laser-assisted bleaching for pro-nounced discolorations. SOLA (International Society for Oral Ap-plications), 4th Laser Congress, Bruges, Belgium 2007.

20. Goharkhay K, Schoop U, Wernisch J, Hartl S, De Moor R,Moritz A. Frequency doubled neodymium:yttrium-aluminum-gar-net and diode laser-activated power bleaching-pH, environmentalscanning electron microscopy, and colorimetric in vitro evalua-tions. Lasers Med Sci 2009;24:339-346.

21. Verheyen P. International patent WO 02/22097 (Issued 14.09.2000).

22. Walsh LJ. Safety issues relating to the use of hydrogen peroxidein dentistry. Aust Dent J 2000;45:257-269.

23. Verheyen P, Walsh LJ, Wernisch J, Schoop U, Moritz A. Laser-as-sisted bleaching. In: Mortiz A, Beer F, Goharkay K, Schoop U,Strassl M, Verheyen P, et al (eds). Oral Laser Application. Quin-tessence: Berlin, 2006:407-448.

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Contact address: Professor Dr. Roeland De Moor, Depart-ment of Operative Dentistry and Endodontology, Ghent Uni-versity, Ghent University Hospital, Dental School, GhentDental Laser Centre, De Pintelaan 185 - P8, B-9000 Gent, Bel-gium. Tel: +32-9-332-4000, Fax: +32-9-332-3851. e-mail: roeland.demoor@ugent.be

Fig 22 Result already after one bleaching appointment and threepasses.

Fig 21 Tetracycline discoloration grade III.Fig 20 Result of a KTP laser bleaching in one appointment.