Review of the current status of tooth whitening with the walking bleach technique

Modified Technique for Nonvital Tooth Bleaching: A Case Report

The aim of this study is to report a case of a nonvital, discolored, maxillary central incisor bleached by 35% hydrogen peroxide gel with the use of glass ionomer cement as a mechanical barrier in an attempt to minimize the undesirable side effects of intracoronal bleaching. The patient was a 13-year-old boy complaining of a discolored nonvital upper-right central incisor and was selected for this study from the pedodontic clinic in the Shibin Elkom teaching hospital in June 2013. After successful endodontic treatment, the tooth was bleached by 35% hydrogen peroxide gel (Opalescence Xtra), activated by a standard curing light unit, and evaluated for any periapical changes by a periapical radiograph for a nine-months follow-up period. Radiographically, there was no evidence of cervical or apical resorption during the study period.

Influence of the bleaching interval on the luminosity of long-term discolored enamel-dentin discs

OBJECTIVES

The aim of this study is to investigate the influence of changing the sodium perborate-tetrahydrate (PBS-4) at a 4-day interval versus no change after 16 days of internal bleaching.

MATERIALS AND METHODS

Two hundred and ten bovine enamel-dentin discs were discolored for 3.5 years with 14 different endodontic materials. All groups with a discoloring index of ∆E (mean) ≥ 5.5 were included in the present investigation: ApexCal (APCA), MTA white + blood (WMTA+BL), Portland cement + blood (PC+BL), blood (BL), MTA gray (GMTA), MTA gray + blood (GMTA+BL), Ledermix (LED), and triple antibiotic paste containing minocycline (3Mix). Fourteen specimens of each group were randomly assigned into two treatment groups: (1) no change of the PBS-4 (n = 7); (2) change of the PBS-4 every 4 days (n = 7). Color measurements were taken at 10 different time intervals and the L*a*b* values were recorded with a spectrophotometer (VITA Easyshade® compact).

RESULTS

In the group 3Mix, significantly better results were achieved by changing the bleaching agent every 4 days (P = 0.0049; q = 0.04), while the group WMTA+BL indicated better results by no change of the bleaching agent (P = 0.0222, q = 0.09). All remaining groups showed no statistical difference between the two treatment procedures.

CONCLUSIONS

Moderate discolorations can be successfully treated without changing the bleaching agent over a period of 16 days. Changing the sodium perborate-tetrahydrate every 4 days is preferred in case of severe discolored enamel-dentin discs only.

CLINICAL RELEVANCE

This approach may offer a reduced number of clinical appointments and a secondary cost reduction to the patient.

Bleaching of a non-vital anterior tooth to remove the intrinsic discoloration

Intrinsic discoloration of a non-vital permanent incisor tooth due to trauma may have a significant esthetic and social impact on children and adolescents. Treatment options for discolored Non-vital teeth are bleaching, crowns or veneers. However, this restorative crown or veneer approach has a significant drawback of being an invasive technique. Intervention should be minimal destruction of tooth structure and should not compromise future restorative options. The advantage bleaching over crown is that it offers simple conservative approach in removal of stain and whitening discolored teeth without damaging tooth structure.

Fracture resistance of endodontically-treated teeth submitted to bleaching treatment with hydrogen peroxide and titanium dioxide nanoparticles photoactivated by LED-laser

Objective: The aim of this study was evaluate the fracture resistance of endodontically-treated teeth after bleaching treatment using 15% hydrogen peroxide plus titanium dioxide nanoparticles (15HPTiO2) photoactivated by LED-laser, in comparison with protocols using 35% hydrogen peroxide (35HP), 37% carbamide peroxide (37CP) or sodium perborate (SP). Material and method: After endodontic treatment, fifty bovine extracted incisors were divided into five groups (n = 10): G1- without bleaching; G2- 35HP; G3- 37CP; G4- 15HPTiO2 photoactivated by LED-laser and G5- SP. In G2 and G4, the bleaching protocol was applied in 4 sessions, with a 7 day interval between each session. In G3 and G5, the materials were kept in the pulp chamber for 21 days, but replaced every 7 days. After 21 days, the crowns were subjected to compressive load at a cross head speed of 0.5 mm/min, applied at 135° to the long axis of the root using an eletromechanical testing machine, until fracture. The data were submitted to ANOVA and Tukey tests (p = 0.05). Result: The bleaching treatment in endodontically-treated teeth with 15HP plus TiO2 nanoparticles and photoactivated by LED-laser caused reduction of the fracture resistance similarly provided by 35HP, 37CP or SP (p>0.05). All bleaching treatments reduced the fracture resistance compared to unbleached teeth (p<0.05). Conclusion: All bleaching protocols reduced the fracture resistance of endodontically-treated teeth, but there were no differences between each other.

Management of the single discoloured tooth. Part 1: Aetiology, prevention and minimally invasive restorative options

The single discoloured tooth is commonly encountered in general practice. This is the first of two articles covering the broad range of management options for the single discoloured tooth. This first part outlines the common causes of discoloration and possible methods of prevention. Minimally invasive techniques are covered. Clinical procedures are outlined and clinical cases used to demonstrate outcomes that can be achieved.

CLINICAL RELEVANCE

The single discoloured tooth is a commonly encountered clinical problem in general dental practice. A wide variety of management options exist and any one in particular may be most appropriate given the clinical scenario. It is therefore essential that general dental practitioners are familiar with the range of options that exist, as well as their indications, and consider adopting minimally invasive techniques in the first instance before moving to more invasive therapies.

Clinical comparison between the bleaching efficacy of light-emitting diode and diode laser with sodium perborate

The aim of this clinical study was to test the efficacy of a light-emitting diode (LED) light and a diode laser, when bleaching with sodium perborate. Thirty volunteers were selected to participate in the study. The patients were randomly divided into two groups. The initial colour of each tooth to be bleached was quantified with a spectrophotometer. In group A, sodium perborate and distilled water were mixed and placed into the pulp chamber, and the LED light was source applied. In group B, the same mixture was used, and the 810 nm diode laser was applied. The final colour of each tooth was quantified with the same spectrophotometer. Initial and final spectrophotometer values were recorded. Mann-Whitney U-test and Wicoxon tests were used to test differences between both groups. Both devices successfully whitened the teeth. No statistical difference was found between the efficacy of the LED light and the diode laser.

Treatment planning the endodontic-implant interface

One of the most challenging treatment planning decisions in restorative dentistry is the retention of a root filled tooth or its extraction and replacement with an implant. Making an informed judgement relies upon not only clinical experience and expertise but also interpretation of the published clinical evidence. In the last few years, more robust data and closer scrutiny of the evidence has helped to understand the advantages and disadvantages of each of these treatment modalities. The purpose of this paper is to provide a narrative review of some of the factors that may influence treatment planning for root canal treated teeth and indications for whether these teeth would be better replaced by an implant. From the evidence presented it is clear that both treatments have a place in contemporary restorative dental treatment and that survival for both root filled teeth and implants are similar. Unsurprisingly, both these treatment choices require high standards of clinical expertise and careful planning to ensure the best outcome.

Fracture resistance of teeth submitted to several internal bleaching protocols

AIM

The aim of this study was to evaluate the fracture resistance of teeth submitted to several internal bleaching protocols using 35% hydrogen peroxide (35HP), 37% carbamide peroxide (37CP), 15% hydrogen peroxide with titanium dioxide nanoparticles (15HPTiO2) photoactivated by LED-laser or sodium perborate (SP).

MATERIALS AND METHODS

After endodontic treatment, fifty bovine extracted teeth were divided into five groups (n = 10): G1-unbleached; G2-35HP; G3-37CP; G4-15HPTiO2 photoactivated by LED-laser and G5-SP. In the G2 and G4, the bleaching protocol was applied in 4 sessions, with 7 days intervals between each session. In the G3 and G5, the materials were kept in the pulp teeth for 21 days, but replaced every 7 days. After 21 days, the teeth were subjected to compressive load at a cross head speed of 0.5 mm/min, applied at 135° to the long axis of the root using an eletromechanical testing machine, until teeth fracture. The data were submitted to ANOVA and Tukey tests (α = 5%).

RESULTS

The 35HP, 37CP, 15HPTiO2 and SP showed similar fracture resistance teeth reduction (p > 0.05). All bleaching treatments reduced the fracture resistance compared to unbleached teeth (p < 0.05).

CONCLUSION

All bleaching protocols reduced the fracture resistance of endodontically-treated teeth, but there were no differences between each other.

CLINICAL SIGNIFICANCE

There are several internal bleaching protocols using hydrogen peroxide in different concentrations and activation methods. This study evaluated its effects on fracture resistance in endodontically-treated teeth.

Effect of Sodium Ascorbate on Dentin Bonding After Two Bleaching Techniques

The purpose of this study was to analyze the influence of 10% sodium ascorbate (SA) on the hybrid layer, resin tag length, and bond strength to dentin after bleaching. Six groups were tested: G C, control; G SA, sodium ascorbate (SA) + restoration; G CP, bleaching with carbamide peroxide (CP) + restoration; G CP+SA, bleaching with CP + SA+ restoration; G HP, bleaching with 35% hydrogen peroxide (HP) + restoration; and G HP+SA, HP + SA + restoration. After dental bleaching, the dentin was exposed and the antioxidant solution was applied to groups G SA, G CP+SA, and G HP+SA, before bonding procedures. The teeth were sectioned in the mesiodistal direction. One section was decalcified, and the specimens were embedded in paraffin and sectioned in the longitudinal direction with a thickness of 6 μm. Fifteen slices of each specimen were selected according to a systematic sample of slices with an interval proportional to the total number of slices obtained for each tooth. The specimens were stained using the Brown & Brenn method, and an optic microscope was used to analyze the hybrid layer thickness and resin tag length. The remaining tooth segment was sectioned into stick-shaped specimens and used for microtensile bond strength testing (0.5 mm/min). Statistical analysis was performed using two-way analysis of variance and Fisher test. The results for hybrid layer + tag formation (in micrometers) were G C, 13.27 Aa; G SA, 11.85 Ba; G CP, 6.84 Bb; G CP+SA, 9.02 Ab; G HP, 7.28 Bb; and G HP+SA, 9.22 Ab; bond strength results (in MPa) were G C, 49.5 Aa; G SA, 51.7 Aa; G CP, 37.16 Bb; G CP+SA, 47.69 Aa; G HP, 32.39 Ab; and G HP+SA, 39.67 Ab. Tooth bleaching with CP or HP impairs the formation of the hybrid layer and resin tags and reduces the microtensile bond strength. Statistically, the use of SA significantly increases the hybrid layer thickness and resin tag length. The microtensile bond strength values for carbamide peroxide increased, but the microtensile bond strength for hydrogen peroxide was not affected.

Effect of endodontic irrigation and dressing procedures on the shear bond strength of composite to coronal dentin

This study aimed to evaluate the effects of three sodium hypochlorite (NaOCl)-endodontic irrigation procedures used alone or in combinations with two intermediate dressing materials on bond strengths of two adhesive composite systems to coronal dentin. Surfaces were treated with NaOCl or NaOCl–Glyde-File-Prep (H₂O₂ and EDTA) with or without chlorhexidine (CHX) as a final rinse. Intermediate dressing materials of calcium hydroxide (Ca(OH)₂) and sodium perborate (SP) were combined with surface treatments. Surface treatment groups (n = 10/group) included (1) distilled water (control), (2) 5.25% NaOCl (30 min), (3) NaOCl/Glyde (30 min), (4) NaOCl/Glyde (30 min) + CHX (2 min), (5) NaOCl/Glyde (30 min) + Ca(OH)₂ (5 days) + CHX (2 min), and (6) NaOCl/Glyde (30 min) + SP (9 days) + CHX (2 min). For each surface treatment group, dentin shear bond strengths of two different composite systems (Excite/Tetric Flow Chroma, [EX/TFC], and Clearfil Protect Bond/Protect Liner F [PB/PLF]) were evaluated. Median shear bond strengths (EX/TFC, PB/PLF) for each surface treatment group in MPa were (1) 21, 18; (2) 26, 18; (3) 21, 17; (4) 22, 16; (5) 17, 11; and (6) 14, 11, respectively. NaOCl significantly increased the bond strength of EX/TFC (p < 0.05), but did not significantly affect that of PB/PLF. The use of NaOCl/Glyde with CHX did not significantly affect EX/TFC (p > 0.05), whereas it significantly decreased PB/PLF (p < 0.05). Ca(OH)₂ and SP significantly decreased the bond strengths of both adhesive systems (p < 0.05). Adhesion to coronal dentin is dependent upon the irrigation regimen and the type of adhesive.

Invasive cervical resorption: treatment challenges

Invasive cervical resorption is a relatively uncommon form of external root resorption. It is characterized by invasion of cervical region of the root by fibrovascular tissue derived from the periodontal ligament. This case presents an invasive cervical resorption occurring in maxillary lateral incisor, following damage in cervical cementum from avulsion and intracoronal bleaching procedure. Flap reflection, debridement and restoration with glass ionomer cement were performed in an attempt to repair the defect. But after 2 mon, more resorption extended apically. Considering root stability and recurrence potential, we decided to extract the tooth. Invasive cervical resorption in advanced stages may present great challenges for clinicians. Therefore, prevention and early detection must be stressed when dealing with patients presenting history of potential predisposing factors.

Discolouration potential of endodontic procedures and materials: a review

Advances in endodontic materials and techniques are at the forefront of endodontic research. Despite continuous improvements, tooth discolouration, especially in anterior teeth, is considered an undesirable consequence following endodontic treatment as it creates a range of aesthetic problems. This article aims to discuss the intrinsic and internalized tooth discolouration caused by endodontic procedures, and to address the discolouration potential of materials used during root canal treatment, including root canal irrigants, intra-canal medicaments, endodontic and post-endodontic filling materials. In addition, the discolouration patterns caused by combined endodontic and nonendodontic aetiological factors are discussed. The recommended guidelines that should be followed by dental practitioners to prevent and manage tooth discolouration are also outlined.

Synthesis of metal ion-histidine complex functionalized mesoporous silica nanocatalysts for enhanced light-free tooth bleaching

Several metal ion-histidine complex functionalized mesoporous silica nanoparticles (MSN) were synthesized and utilized as efficient catalysts for enhanced and light-free tooth bleaching. Fe(II), Mn(II), and Cu(II) ions were successfully immobilized in histidine-functionalized MSN and their catalytic abilities against discoloration of a dye (Orange II) in both test tubes and extracted tooth models were compared and discussed. Through direct observation of test tubes and calculation of mean color changes of extracted teeth we concluded that Fe(II)-his-MSN exhibited better catalytic competence than Mn(II)-his-MSN and Cu(II)-his-MSN because of its intrinsic redox ability. In test tubes Orange II was completely degraded within 6 h when Fe(II)-his-MSN was used as the catalyst. For the extracted tooth model the presence of Fe(II)- or Mn(II)-his-MSN significantly enhanced the efficacy of tooth bleaching for three regions, the enamel, outer dentin, and inner dentin, of stained teeth compared with H(2)O(2) alone. Furthermore, unlike current tooth bleaching techniques that need an LED or laser to catalyze H(2)O(2) bleaching, we demonstrated a light-free tooth bleaching system using Fe(II)-his-MSN as an efficient and reliable catalyst.

Whitening the single discolored tooth

This article discusses the possible methods available for whitening of a single discolored tooth. Treatment options can vary from restorative procedures such as crowns, veneers, or bonding to more conservative bleaching treatments. The long-term success of the treatment is dictated by proper diagnosis and treatment planning. The cause and severity of the discoloration has to be carefully evaluated when planning for bleaching options. The vitality of the pulp, presence and absence of symptoms, and periapical pathoses usually determine whether an external or internal bleaching approach will be considered.

Diffusion of peroxides through dentine in vitro with and without prior use of a desensitizing varnish

Different bleaching regimens are used in dentistry possibly penetrating the dentine and affecting the pulp. The aim of the present study was to investigate peroxide diffusion through dentine pre-treated with a desensitizing varnish (Vivasens®) in a standardized in vitro setup during application of different bleaching materials. The penetration was tested using 1.3-mm-thick bovine dentine slabs. The following bleaching materials were tested with and without prior application of the desensitizing varnish on the external side of the dentine slabs: Vivastyle, Whitestrips, Simply White, Opalescence (external bleaching), and sodium perborate (internal bleaching, only tested without varnish; n = 8 samples per subgroup). The penetration of peroxides was measured photometrically using 4-aminoantipyrin as a substrate, the penetration of peroxides was monitored over 240 min. All bleaching agents yielded a diffusion of peroxides through the dentine, the kinetics of penetration were approximately linear for all materials tested. The significantly highest diffusion of peroxides was observed with Opalescence, the lowest with sodium perborate. The adoption of the desensitizing varnish reduced the diffusion of peroxides significantly for all external bleaching materials. Peroxides penetrated the dentine during application of bleaching materials; the penetration of peroxides can be reduced by application of a desensitizing agent.

Effect of light-activated bleaching on the microleakage of Class V tooth-colored restorations

OBJECTIVE

In-office bleaching procedures utilizing highly concentrated 30%-35% hydrogen peroxide solutions or hydrogen peroxide releasing agents are used for tooth whitening. Some recommend that, to enhance the whitening process, light-activation of the bleaching agent should be performed. The current study evaluated the effect of plasma arc bleaching on the microleakage of Class V restorations restored with resin composite, compomer and resin-modified glass ionomer (RMGI).

MATERIALS AND METHODS

The buccal surfaces of 72 freshly extracted premolars were prepared with Class V cavities (4 x 2.5 x 1.5 mm) extended 1 mm apical to the CEJ. The prepared teethwere randomly divided into six groups. The cavities were restored with Single Bond and Z100 resin composite (Groups 1 and 2), Prompt L-Pop and F2000 compomer (Groups 3 and 4) and Vitremer RMGI (Groups 5 and 6), respectively. They were then thermocycled for 500 cycles. The samples from Groups 1, 3 and 5 were incubated at 37 degrees C and 100% humidity. Groups 2, 4 and 6 were bleached using in-office bleaching gel and the plasma arc bleaching unit, then incubated. All samples were sealed with nail varnish and immersed in 2% basic fuschin for 24 hours. The restorations were sectioned longitudinally and microleakage was evaluated using a scale ranging from 0 to 3. The data were analyzed using the Kruskal-Wallis test (alpha = 0.05).

RESULTS

No statistically significant differences between study groups were observed in both the enamel and dentinal margins (p > 0.05).

CONCLUSION

Plasma arc bleaching did not significantly affect the microleakage of existing tooth-colored restorations restored with Z100 resin composite, F2000 compomer and Vitremer RMGI.

Tooth bleaching with nonthermal atmospheric pressure plasma

We demonstrated that room temperature plasma could be used for tooth bleaching. A nonthermal, atmospheric pressure, helium plasma jet device was developed to enhance the tooth bleaching effect of hydrogen peroxide (H(2)O(2)). All teeth were sectioned sagittally into halves, which were assigned randomly to either the experimental group or the control group. The experimental group was treated with H(2)O(2) (28%, 20 microL every 30 seconds) plus plasma (5 W) for 10 minutes; the control group was treated with H(2)O(2) alone for the same duration. Removal of the tooth surface protein was demonstrated by scanning electron microscopy images and Ponceau staining. Production of hydroxyl radicals (.OH) was measured by using electron spin resonance spin-trapping. Combining plasma and H(2)O(2) improved the bleaching efficacy by a factor of 3 compared with using H(2)O(2) alone. Tooth surface proteins were noticeably removed by plasma treatment. When a piece of tooth was added to a solution of H(2)O(2) as a catalyst, production of *OH after plasma treatment was 1.9 times greater than when using H(2)O(2) alone. We suggest that the improvement in tooth bleaching induced by plasma is due to the removal of tooth surface proteins and to increased *OH production.

Undesirable and adverse effects of tooth-whitening products: a review

Hydrogen peroxide (H(2)O(2)) is a powerful oxidising agent. It gives rise to agents known to be effective bleaching agents. The mechanisms of bleaching involve the degradation of the extracellular matrix and oxidation of chromophores located within enamel and dentin. However, H(2)O(2) produces also local undesirable effects on tooth structures and oral mucosa. In clinical conditions, the daily low-level doses used to produce tooth whitening never generate general acute and sub-acute toxic effects. Genotoxicity and carcinogenicity only occur at concentrations that are never reached during dental treatments. Some transient adverse effects have been reported on the oral mucosa and the digestive tract if the product is swallowed. Local effects may occur on the oral mucosa and dental tissues during whitening, namely, pulp sensitivity, cervical resorption, release of selected components of dental restorative materials, and alteration of the enamel surface. Most of the local effects are dependent of the technique and concentration of the product so far used, but as the results of bleaching obtained are not stable, repeated treatments add to the adverse effects. The informed decision to administer or not and the control of bleaching effects should stand in the hand of dental surgeons and certainly not as it appears at present, as cosmetics sold without any restriction despite the potential health hazards of peroxides.

Bleaching a devital primary tooth using sodium perborate with walking bleach technique: a case report

Nowadays, both children and parents place a greater value on appearance and aesthetics than has previously been the case. Primary teeth with intrinsic discoloration may be treated by a number of methods, including facings and abrasion. However, dental bleaching may offer a safer alternative that can be completed with less chair time and without harming dental structures. This case report describes the treatment of a darkened primary tooth of a 4-year-old boy with sodium perborate using the walking bleach technique and its 1-year clinical and radiographical follow-up. During this 1-year follow-up period, no signs of any pathology were observed either clinically (sensitivity to percussion or palpation, fistulae, color change) or radiographically (external or internal root resorption, apical radiolucency). In this study, using sodium perborate with the walking bleach technique is found to be successful in whitening primary teeth and can be recommended as a safe alternative for the bleaching of devital primary teeth with intrinsic discoloration.

Oxygen release of tetra acetyl ethylene diamine (TAED) and sodium perborate combination

AIM

To evaluate the effect of tetra acetyl ethylene diamine (TAED) on oxygen release from sodium perborate and to compare it with sodium perborate-hydrogen peroxide (H(2)O(2)) and sodium perborate-distilled water mixtures.

METHODOLOGY

Six groups were evaluated: control groups (groups I-III), sodium perborate was mixed with distilled water or 3% or 30% H(2)O(2); experimental groups (groups IV-VI), sodium perborate was mixed with TAED in different ratios and then distilled water was added to these mixtures. The amount of oxygen released from the samples was measured with a digital oxygen meter at room temperature (25 degrees C) and body temperature (37 degrees C) after 1 min, 1-6 h and 12 h and on each day up to 1 week. The results were statistically evaluated by one-way analysis of variance and post hoc Tukey's tests.

RESULTS

The TAED groups demonstrated significantly higher amounts of released oxygen after 1 min and 1 h at 25 degrees C and 1 min at 37 degrees C (P < 0.05). At all other measurement times, the amount of TAED in each mixture did not alter the amount or speed of oxygen release (P > 0.05).

CONCLUSIONS

Tetra acetyl ethylene diamine groups achieved their maximum oxygen release 2 h earlier at 25 degrees C and 1 h earlier at 37 degrees C than the other groups. Thus, TAED accelerated oxygen release from sodium perborate-distilled water mixtures regardless of its proportions up to 24 h.

12-month color stability of enamel, dentine, and enamel-dentine samples after bleaching

The study aimed to quantify the color regression of enamel (E), dentine (D), and combined enamel-dentine (ED) of differently bleached ED specimens over a period of 12 months in vitro. Two ED samples were obtained from the labial surfaces of bovine teeth and prepared to a standardized thickness with the enamel and dentine layer each 1 mm. The ED samples were distributed on four groups (each n = 80), in which the different bleaching products were applied on enamel (1, Whitestrips; 2, Illuminé 15%; 3, Opalescence Xtra Boost) or dentine surfaces (4, mixture of sodium perborate/distilled water). Eighty ED samples were not bleached (control). Color (L*a*b*) of ED was assessed at baseline, subsequently after bleaching and at 3, 6, and 12 months of storage after bleaching (each 20 samples/group). E and D samples were prepared by removing the dentine or enamel layer of ED samples to allow for separate color analysis. Bleaching resulted in a significant color change (Delta E) of ED specimens. Within the observation period, Delta L but not Delta b declined to baseline. L* values of E and D samples also declined and were not significantly different from control samples after 12 months, while b* values did not decrease to baseline. Generally, no differences between the bleaching agents could be observed. Color change of enamel, dentine, and combined ED of in vitro bleached tooth samples is not stable over time with regard to lightness. However, yellowness did not return to baseline within 1 year.

Nonvital tooth bleaching: a review of the literature and clinical procedures

Tooth discoloration varies in etiology, appearance, localization, severity, and adhesion to tooth structure. It can be defined as being extrinsic or intrinsic on the basis of localization and etiology. In this review of the literature, various causes of tooth discoloration, different bleaching materials, and their applications to endodontically treated teeth have been described. In the walking bleach technique the root filling should be completed first, and a cervical seal must be established. The bleaching agent should be changed every 3-7 days. The thermocatalytic technique involves placement of a bleaching agent in the pulp chamber followed by heat application. At the end of each visit the bleaching agent is left in the tooth so that it can function as a walking bleach until the next visit. External bleaching of endodontically treated teeth with an in-office technique requires a high concentration gel. It might be a supplement to the walking bleach technique, if the results are not satisfactory after 3-4 visits. These treatments require a bonded temporary filling or a bonded resin composite to seal the access cavity. There is a deficiency of evidence-based science in the literature that addresses the prognosis of bleached nonvital teeth. Therefore, it is important to always be aware of the possible complications and risks that are associated with the different bleaching techniques.

Reversal of Compromised Bonding in Bleached Enamel Using Antioxidant Gel

Dental bond strength is significantly reduced when bonding is performed immediately after bleaching treatments. It has also been reported that the application of an antioxidant after bleaching treatment improves the adhesive bond strength of oxidized enamel tissue. The application of an antioxidant in gel form by the patient makes the application process easier and shortens time spent in the clinic.

Efficacy and tolerability of two home bleaching systems having different peroxide delivery

The aim of this study was to investigate tooth whitening efficacy and oral side effects during bleaching with Whitestrips (WS) (6% hydrogen peroxide H(2)O(2) gel) and Vivadent Vivastyle (VS) (10% carbamide peroxide gel). Forty-seven subjects were included in this single blind, randomized, parallel group study. Application of WS was performed twice a day for 30 min. Trays filled with VS were worn for 60 min once a day. Tooth color was evaluated by measuring L*a*b* values before the study and after completion of the bleaching. Treatment tolerability was monitored throughout bleaching with an 8-week follow-up after completion of therapy. After 2 weeks both treatment groups demonstrated significant improvements in tooth color compared to baseline. A shift toward less yellow (-Deltab) and brighter (+DeltaL) tooth color was observed. Deltab amounted to -1.69 +/- 0.38 for WS and -1.20 +/- 0.34 for VS (mean value +/- SE). DeltaL was +1.55 +/- 0.41 for WS and +1.20 +/- 0.37 for VS. There was no significant difference between the two systems. No significant differences between the two bleaching systems were recorded for clinically observed signs or reported symptoms. Gingival irritation was observed in 13%, reported tooth hypersensitivities in 22% and reported gum irritation in 20% of the total study population. At an 8-week follow-up visit no adverse effects were observed. Both WS and VS demonstrated significant and comparable levels of tooth color improvement after 2 weeks. Each treatment caused similar levels of transient oral side effects.

External bleaching therapy with activation by heat, light or laser—A systematic review

OBJECTIVE

External bleaching procedures utilizing highly concentrated 30-35% hydrogen peroxide solutions or hydrogen peroxide releasing agents can be used for tooth whitening. To enhance or accelerate the whitening process, heat-activation of the bleaching agent by light, heat or laser is described in the literature. The aim of the present review article was to summarize and discuss the available information concerning the efficacy, effects and side effects of activated bleaching procedures.

SOURCES

Information from all original scientific full papers or reviews listed in PubMed or ISI Web of Science (search term: (bleaching OR brightening OR whitening OR colour) AND (light OR laser OR heat OR activation)) were included in the review.

DATA

Existing literature reveals that activation of bleaching agents by heat, light or laser may have an adverse effect on pulpal tissue due to an increase of intra-pulpal temperature exceeding the critical value of 5.5 degrees C. Available studies do not allow for a final judgment whether tooth whitening can either be increased or accelerated by additional activation.

CONCLUSION

Therefore, application of activated bleaching procedures should be critically assessed considering the physical, physiological and patho-physiological implications.

Time-Course Diffusion of Hydrogen Peroxide Through Human Dentin: Clinical Significance for Young Tooth Internal Bleaching

The purpose of this study was to record the time-course diffusion of hydrogen peroxide through human dentin from a peroxide carbamide gel designed for the walking bleach technique in order to determine its optimal renewal time. It was considered that the optimal renewal rate corresponded to the time necessary to achieve 80% of the maximal diffusion because a much longer time does not involve further significant diffusion. Thirty-six freshly extracted human premolars were used for this study. Eighteen were extracted for orthodontic reasons on patients under 20 years old (young-teeth group). Eighteen were extracted for periodontal reasons on patients between 40 and 60 years old (old-teeth group). The teeth were endodontically treated, and a flat defect was created at the enamel-cementum junction. The teeth were suspended in vials containing water, and the access cavities were filled with 20 microL of 20% hydrogen peroxide gel. The amount of diffusing hydrogen peroxide was assessed at 1 hour, 24 hours, 48 hours, and 120 hours. The diffusive flux and the maximal diffusion were calculated as well as the optimal renewal time. Hydrogen peroxide diffusion through young teeth lasted 352 hours but lasted 291 hours through old teeth. Diffusive flux and maximal diffusion were higher through young teeth than through old teeth. The optimal renewal time for young teeth was 33 hours and for old teeth was 18 hours.

Efficacy and oral side effects of two highly concentrated tray-based bleaching systems

The aim of this study was to investigate the tooth-whitening efficacy and oral side effects of the two tray-based bleaching systems Visalys whitening (VW) and Opalescence PF (OP). A stratified, randomised distribution of the subjects (n = 60) to two treatment groups was performed according to baseline tooth brightness (L* values) as determined by colourimeter and to the criteria smoker/non-smoker. Tooth colour was evaluated by measuring L*a*b* values generated from standardised digital image analysis with Adobe Photoshop of the facial surfaces of the right central maxillary incisor. Tooth hypersensitivity, with intensity graded from 0 (no hypersensitivity) to 10 (high hypersensitivity), was assessed chair-side using an air syringe. After bleaching therapy, both treatment groups demonstrated significant improvements in tooth colour (p < or = 0.05). A shift towards less yellow (-Deltab*) and brighter (+DeltaL*) tooth colour was observed. Deltab* was significantly higher in the OP group in comparison to the VW group, DeltaL* showed no significant difference between the both treatment groups (p < or = 0.05). After bleaching, the intensity of tooth hypersensitivity was increased significantly compared to baseline in both groups (p < or = 0.05), with no significant difference between the both groups. Both highly concentrated bleaching systems are effective as tooth-whitening systems, with few reported side effects such as transient tooth hypersensitivity.

Cosmetic dentistry

PURPOSE OF REVIEW

Patients seeking the expertise of facial plastic surgeons for facial aesthetic improvement may also desire or benefit from dental aesthetic procedures. This paper reviews current treatment options available in cosmetic dentistry.

RECENT FINDINGS

Many techniques exist to improve dental aesthetics in color, position, shape, size, alignment and overall smile appearance. Although orthodontic therapy is still an important modality for smile aesthetics, some simpler procedures can provide acceptable aesthetic results. Comparison of external dental bleaching techniques reveals similar long-term results for in-office and at-home bleaching; in-office treatments, however, may provide the benefit of faster results. Internal dental bleaching is an effective method for correcting nonvital teeth coloration. Enamel shaping via either direct tooth contouring or the application of resins or veneers to tooth surfaces can correct defects, asymmetries and shape or rotation problems. Veneers or crowns are also options to correct intrinsic dental stains not amenable to bleaching techniques. Treatments to refine gingival margins and borders are another proven beneficial cosmetic procedure.

SUMMARY

A myriad of techniques exist to correct a patient's particular concerns. Correction of discoloration is usually feasible as is the improvement of a patient's smile and overall dental aesthetics.

In Vitro Assessment of a Gel Base Containing 2% Chlorhexidine as a Sodium Perborate’s Vehicle for Intracoronal Bleaching of Discolored Teeth

The purpose of this study was to assess a gel base containing 2% chlorhexidine (CHX) as a vehicle to be mixed with sodium perborate for intracoronal bleaching of discolored teeth, comparing its bleaching efficacy to sodium perborate mixed with other vehicles; 37% carbamide peroxide and 30% hydrogen peroxide. There were 110 fresh bovine incisors artificially stained using whole blood. The samples were divided into 11 groups and the intracoronal bleaching was performed using the "walking bleach technique". The bleaching agents were replaced three times at 7-day intervals. Using digital photos and a shade guide created for bovine teeth, the samples were evaluated at day 0, 7, 14, 21, and 28. On evaluation day, the photos were examined by three endodontists giving scores from 1 to 5 based on the shade guide created. Data were analyzed statistically by Kruskall-Wallis test. After 28 days, all evaluated teeth received scores that were statistically similar. Groups that used sodium perborate and a liquid vehicle bleached faster than those that used a gel based vehicle. The CHX gel allowed dissociation for the bleaching agent. The 2% CHX gel exhibited a good potential for use as a vehicle for sodium perborate or as a complement for carbamide peroxide.

Endodontic problems

If modern clinical techniques were carefully followed, many common endodontic problems would never occur. Incorrectly designed access cavities may make root canals both difficult to identify and to instrument. Careful study of the pre-operative radiograph is essential. Various aids are available to remove fractured instruments and failed root fillings, but the problem must first be correctly diagnosed. As more patients seek cosmetic procedures, the practitioner should be familiar with the 'walking bleach' procedure, again after careful diagnosis of the cause of the discolouration. The practitioner should also be fully aware of the prognosis for this and other endodontic procedures.