Bleaching Sessions Research Articles

Tooth sensitivity and bleaching effectiveness associated with use of a calcium-containing in-office bleaching gel

The authors conducted a study to evaluate tooth sensitivity (TS) and the bleaching effectiveness associated with use of a calcium-containing (CC) in-office bleaching gel. The authors used a 35 percent calcium-free (CF) hydrogen peroxide gel and a 35 percent CC hydrogen peroxide gel according to the manufacturer's instructions in 40 caries-free participants 18 years or older. They performed two bleaching sessions with a one-week interval between sessions. The authors registered the color at baseline and after the first and second bleaching sessions by using a shade guide and by gauging the participant's perception of TS as registered on a scale from 0 (none) to 4 (severe). The authors evaluated the bleaching effectiveness at each week's recall visit by means of the Friedman test, and they compared the groups at each assessment point by means of the Mann-Whitney test. They evaluated the percentage of participants with TS and the intensity of the TS by using the Fisher exact and Mann-Whitney tests. Both groups demonstrated equivalent and significant tooth color enhancement compared with color values at baseline (P < .05), with an average bleaching of 7 to 8 shade guide units. Most of the participants from the CF group (80 percent) experienced sensitivity while undergoing the bleaching regimen, whereas only 40 percent of participants from the CC group reported experiencing TS (P = .02). The intensity of TS was significantly higher (P < .01) for the CF group during in-office dental bleaching. The CC 35 percent hydrogen peroxide gel reduced the TS during in-office dental bleaching without jeopardizing the bleaching effectiveness. The results of this study support the findings that a CC 35 percent hydrogen peroxide gel can reduce TS during in-office dental bleaching.

Effect of Light Activation on Tooth Sensitivity After In-Office Bleaching

This clinical study evaluated the effects of light-emitting diode (LED)/laser activation on bleaching effectiveness (BE) and tooth sensitivity (TS) during in-office bleaching. Thirty caries-free patients were divided into two groups: light-activated (LA) and non-activated (NA) groups. A 35% hydrogen peroxide gel (Whiteness HP Maxx, FGM Dental Products, Joinville SC, Brazil) was used in three 15-minute applications for both groups. For the LA group, LED/laser energy (Whitening Lase Light Plus, DMC Odontológica, São Carlos SP, Brazil) was used, in accordance with the manufacturer's directions. Two sessions of bleaching were performed at one-week intervals. Color was registered at baseline and after the first and second bleaching sessions using a Vita shade guide. Patients recorded TS on a 0 to 4 scale during bleaching and within the next 24 and 48 hours of each session. BE at recall each week and intensity of TS were evaluated by repeated measures analysis of variance (ANOVA) and Tukey tests (α=0.05). Tooth sensitivity was compared using the Friedman repeated measures analysis of variance by rank and the Wilcoxon sign-ranked test. Faster bleaching was observed for the LA group than for the NA group after the first session (4.8 and 3.8 shade guide units [SGUs]; p=0.0001). However, both techniques were capable of bleaching the same number of SGUs after the second bleaching session (p=0.52). Most of the LA group (53.3%) had sensitivity even 24 hours after each bleaching session, but only 26.6% from the NA group reported TS. The intensity of TS was similar for both groups immediately after bleaching but significantly higher for the LA group 24 hours after each bleaching session (p=0.001). After two bleaching sessions, the use of LED/laser light activation did not improve bleaching speed. Persistent tooth sensitivity and higher tooth sensitivity after 24 hours of bleaching were observed when light activation was used.

Color alteration in teeth subjected to different bleaching techniques

This study evaluated the color alteration of teeth subjected to the action of different bleaching agents and the influence of light sources commonly used in association with these products, In GI, the specimens remained immersed in artificial saliva. The specimens in GII were bleached with a 10% carbamide peroxide gel 4 hours/day during 3 weeks; the teeth in the other three groups were subjected to three sessions of three 10-min applications of 35% hydrogen peroxide gel at 7-day intervals. In GIII, no light was used, while in GIV and GV the gel was associated with a quartz-tungsten-halogen light and a LED/laser source, respectively. The teeth color was evaluated before and 7 days after the bleaching sessions by reflectance spectrophotometry. Data were analyzed statistically by ANOVA and Fisher’s test (α = 0.05), and showed that a significant color change was obtained in all treated groups. After the first week of treatment and at the end of it, the bleaching protocols showed similar results. The results of the present study indicate that association of a light source is not necessary to obtain the bleaching effect and that optimal bleaching can be achieved with all techniques tested.

In vitro colorimetric evaluation of the efficacy of various bleaching methods and products

<h3>Objective</h3> Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficacy is unknown. The aim of this in vitro study was to evaluate the ability of different bleaching products and protocols to lighten enamel and dentin. <h3>Method and Materials</h3> Bovine tooth samples of standardized thickness (2.5 ± 0.025 mm with similar dentin and enamel thicknesses) were prepared and stained with whole blood and hemolysate before being submitted to 11 different bleaching regimens: home bleaching using 10%, 15%, 16%, or 20% carbamide peroxide, power bleaching using 15% hydrogen peroxide, 30% hydrogen peroxide, or 25% carbamide peroxide with or without light activation, and over-the-counter bleaching strips containing 5.3% hydrogen peroxide. Colorimetric measurements were performed on each sample side, according to the CIE L^{∗^a∗}b^∗ system, before and after staining as well as after each series of 5 bleaching sessions (number of applications varied from 5 to 20 times, according to the bleaching protocol). <h3>Results</h3> All products and protocols produced a similar bleaching effect on enamel, while the home bleaching regimen proved largely superior to lighten dentin. <h3>Conclusion</h3> In-office bleaching techniques proved less efficient than home bleaching for removing stains deposited in dentin.—<i>Reprinted with permission of Quintessence Publishing</i>.

Effect of Prolonged Direct and Indirect Peroxide Bleaching on Fracture Toughness of Human Dentin

The effects of prolonged exposure to peroxide bleaching agents on dentin structural integrity are uncertain. To evaluate the effect of in vitro prolonged tooth bleaching on the fracture toughness (K(1C)) of human dentin. Dentin from recently extracted molar teeth was directly or indirectly treated to simulate a prolonged at-home (10% carbamide peroxide or 3% hydrogen peroxide, 6 hours/day, 5 days/week for 8 weeks) or in-office (30% hydrogen peroxide, 1 hour/week for 8 weeks) bleaching regimen (N=8/group). Placebo gel and distilled water acted as control materials. Compact tension test specimens (approximately 4.60 x 4.50 x 1.60 mm) were prepared from coronal dentin and tensile loading was applied at a rate of 10 mm/min 24 hours after the last bleaching session. Results were analyzed using analysis of variance and Tukey's test (p < 0.05). For direct bleach application, the treatment materials were applied onto dentin that was already prepared as compact tension specimens. For indirect bleach application, bleach was applied to the enamel of intact teeth prior to specimen preparation. There was a significant decrease in dentin K(1C) after 8 weeks of direct bleach treatment (p < 0.05). There were no significant differences between the bleach and control groups after 8 weeks of indirect bleach treatment (p=0.19). The in vitro fracture resistance of dentin was reduced after the prolonged use of bleach products that were applied directly to dentin. Caution should be considered when using bleach for prolonged treatment times in clinical cases where there is dentin exposure such as occlusal attrition or gingival recession.

Clareamento externo para dentes com calcificação distrófica da polpa: relato de caso clínico

Este trabalho descreve o tratamento de dentes com calcificação distrófica da polpa, que envolve geralmente uma alteração na cor do dente. Tradicionalmente, esses dentes eram tratados de maneira invasiva com confecção de facetas ou coroas dentárias. O clareamento externo é uma alternativa de tratamento que possibilita uma solução estética, conservadora e biológica, especialmente nos casos em que há uma dificuldade de acesso ao sistema de canais radiculares. O presente caso clínico mostra uma paciente que apresentava alteração de cor no incisivo central superior esquerdo, decorrente de calcificação distrófica total da câmara pulpar e do canal radicular, em função de um trauma. O tratamento englobou trinta dias de clareamento caseiro supervisionado, a partir do uso de moldeira com o gel de peróxido de carbamida a 16% e mais duas sessões de clareamento de consultório com peróxido de hidrogênio a 35% para resolver a intensa saturação no colo do dente.

Composite resin color change after vital tooth bleaching

Color change of composite resin was determined with the Minolta Chroma meter (CR-100) after four sessions of vital bleaching. Specimens of selected composite resin materials were subjected to vital bleaching (37% H 3PO 4/1 minute, then 30% H 20 2/infrared light/30 minutes.) Specimens were stored in water between bleaching. Control specimens were used to determine the effects of water storage alone. Initial L *a *b * color readings were made on 24-hour hydrated specimens. Final L *a *b * readings were made on 24-hour hydrated specimens. Calculations were made for the A E values for each specimen. Mean Δ E values and standard deviations were obtained for each material. Two-way ANOVA and Newman-Keuls analyses showed significant (α = 0.05) color change for most bleached materials. Additionally, some materials had Δ E values greater than 3. These were visibly lighter compared to their controls. Vital bleaching produced color change in most composites as measured with the Chroma meter. This technique may be used to lighten dark-colored or stained composite resin restorations.