Dental color standards: shade tab arrangement

Purpose: The aim of this study was to analyze the shade tab arrangement of two popular dental shade guides, suggest possible improvements, and propose clinical guidelines. Materials and Methods: Data were recorded using a colorimeter set to standard illuminant source C and CIE L*a*b* system. The manufacturers' shade tab arrangement as well as the possible improvements in the arrangement of shade tabs of Vitapan Classical and Vitapan 3-D Master (Vita Zahnfabrik, Bad Säckingen, Germany) shade guides were examined by regression analysis. Results: Certain shortcomings in the manufacturers' arrangement of both color standards were observed. The Vitapan 3-D Master arrangement was more consistent, but with a decrease in lightness, tab saturation decreased as well in four of its five groups. When Vitapan Classical and Vitapan 3-D Master tabs were arranged according to ΔE* in relation to the lightest tab, r² was 0.98 and 0.96, respectively. After dividing the total ΔE* range into four equal segments for the newly established Vitapan Classical guide, r² was 0.91, 0.95, 0.68, and 0.94, respectively. Corresponding r² values for Vitapan 3-D Master were 0.96, 0.94, 0.90, 0.94, and 1.0.
CLINICAL SIGNIFICANCE
Total color difference in relation to the lightest tab, followed by the tab division into an adequate number of groups, is recommended as a possible and universally applicable mode of tab arrangement in dental color standards.     

A one-dimensional color order system for dental shade guides

The purpose of this study was to re-arrange the master Bioform shade guide into a long-range one-dimensional color system based upon color difference. Although most shade guides may show local order when arranged according to hue, long-range order has not been established. However, shade guide arrangement according to a logical color order would be an advantage to the user. The first step in determining the color order was to measure the color of the shade guide teeth. A methodology was developed for measuring the color by use of a reflectance spectrophotometer. The precision of measurement was determined to be equal to CIE L*a*b* delta E of 0.5. Spectra were obtained and converted into CIE L*a*b* and Munsell notation. The measured colors of the Bioform shades ranged from a Munsell hue of 0.9 Y to 3.5 Y; a value of 6.6 to 7.8; and a chroma of 1.9 to 4.1. The teeth were then arranged visually from light to dark. The correlation coefficient between the visual ranking and color difference was 0.95. There was an inverse correlation between visual ranking and Munsell value, with a correlation coefficient of 0.90. Therefore, the sequence according to color difference provided the better agreement with visual perception.     

Evaluation of a newly developed visual shade-matching apparatus

PURPOSE: This study evaluated a newly developed visual shade-matching apparatus, Shademat Visual+, as well as the influence of tab arrangement, clinician gender, and years in practice on shade-matching quality. MATERIALS AND METHODS: A group of 129 color-normal evaluators-dental students and general dentists-matched the shade of four ceramometal crowns using the Vitapan Classical shade guide. Crowns were positioned onto the upper member of an artificial head and fastened to the headrest of the dental chair or Shademat Visual+. Shade tabs were arranged according to the manufacturer's suggestion or according to deltaE* in relation to the "lightest" tab and divided into groups (alternative arrangement). The evaluators matched the shade of four ceramometal crowns both in daylight and using the Shademat Visual+ artificial light source. The color coordinates were determined using digital image analysis. Based on deltaE* values, each shade-matching result was ranked from 1 (the worst match) to 16 (the best match) points. RESULTS: The evaluators achieved a better result in Shademat Visual+ trials than in daylight trials (13.2 points vs 12.4 points; P < .001). For the same ceramometal crown, 12.7 points were recorded in daylight trials with the manufacturer-suggested arrangement, and 13.7 were recorded with the alternative arrangement (P< .001). Corresponding values for Shademat Visual+ trials were 13.6 points and 14.6 points, respectively (P< .001). Female-male and student-dentist evaluator differences were not significant. CONCLUSION: The Shademat Visual+ apparatus enabled better shade-matching results than daylight. The alternative tab arrangement enabled better results than the manufacturer-suggested one. Gender and years in practice did not influence shade-matching quality.     

Shade Matching Assisted by Digital Photography and Computer Software

Purpose: To evaluate the efficacy of digital photographs and graphic computer software for color matching compared to conventional visual matching.
Materials and Methods: The shade of a tab from a shade guide (Vita 3D-Master Guide) placed in a phantom head was matched to a second guide of the same type by nine observers. This was done for twelve selected shade tabs (tests). The shade-matching procedure was performed visually in a simulated clinic environment and with digital photographs, and the time spent for both procedures was recorded. An alternative arrangement of the shade tabs was used in the digital photographs. In addition, a graphic software program was used for color analysis. Hue, chroma, and lightness values of the test tab and all tabs of the second guide were derived from the digital photographs. According to the CIE L*C*h* color system, the color differences between the test tab and tabs of the second guide were calculated. The shade guide tab that deviated least from the test tab was determined to be the match. Shade matching performance by means of graphic software was compared with the two visual methods and tested by Chi-square tests (α= 0.05).
Results: Eight of twelve test tabs (67%) were matched correctly by the computer software method. This was significantly better ( p < 0.02) than the performance of the visual shade matching methods conducted in the simulated clinic (32% correct match) and with photographs (28% correct match). No correlation between time consumption for the visual shade matching methods and frequency of correct match was observed.
Conclusions: Shade matching assisted by digital photographs and computer software was significantly more reliable than by conventional visual methods.     

牙科着色氧化钇稳定四方多晶氧化锆陶瓷的制备及颜色性能

目的添加不同着色剂组合配制着色的牙科氧化钇稳定四方多晶氧化锆（3Y-TZP）陶瓷,并测定其颜色性能。方法将TZ-3Y-S粉体与一定组分的着色剂球磨混合后,在200 MPa压力下等静压成型,在1 500 ℃烧结2 h,烧制5种具有一定颜色的氧化锆材料,每个颜色组分别制备10 mm×10 mm×0.5 mm和10 mm×10 mm×1 mm着色氧化锆陶瓷片,在黑色背景下用柯尼卡美能达CM-2600d分光光度计进行颜色测定,并与VITA In-Ceram YZ染色液比色板颜色作比较。结果通过对粉体进行着色,配制出具有一定颜色的本体着色氧化锆陶瓷材料,颜色明度逐级降低,饱和度逐渐增大,2种厚度3Y-TZP陶瓷的颜色片色差较小,颜色空间范围是L*：67.76～77.78;a*：-2.19～3.80;b*：12.13～25.01。与VITA In-Ceram YZ染色液比色板相比,颜色空间近似,但明度的最低值仍较高。结论着色氧化锆陶瓷材料适宜用于临床上与饰面瓷颜色匹配,有必要再进一步研究低明度的着色氧化锆色片。     

松风HALO比色板的色度分析

目的：研究松风HALO比色板比色片的颈部、体部、切端部色度分布规律,以利提高临床医师对比色板颜色的判断能力。方法：采用数码摄影和计算机技术对松风HALO比色板的牙颈部、牙体部、切端部进行测量,根据比色板体部、颈部、切端部的L*、a*、b*、C*值分别绘制A、B、C、D、R、VR各组色介的L－C曲线及其a*-b*散点分布图。结果：松风HALO比色板各组颜色排列具有一定的规律性,随着A、B、C、D、R、VR各组比色板色阶的增大,颈部、体部、切端部的L＊值呈递减趋势,a*、b*值呈递增趋势。结论：比色板各组颜色排列的序列性,有助于临床医师对比色板颜色的判断。新增加三组根部色和两组偏红色,有利于对牙周病患和具有偏红色牙齿的比色。     

Color difference of four esthetic restorative materials by the illuminant

PURPOSE: To determine the difference in lightness, chroma, hue angle and color of four kinds of esthetic restorative materials of the same shade designation by the change of standard illuminants of D65 (daylight), A (incandescent lamp) and F2 (fluorescent lamp). METHODS: Spectral reflectance and color of four resin composites, a glass ionomer, a resin-modified glass ionomer and a compomer of shade A2 were measured according to the CIELAB color scale relative to the illuminants D65, A and F2. Spectral reflectance curves were compared, and changes in lightness (deltaL*), chroma (deltaC*ab), hue angle (deltah degrees) and color (deltaE*ab) by the changes of illuminants from D65 to A or F2 were compared as "value relative to the illuminant A or F2 - value relative to the illuminant D65". RESULTS: In curves of spectral reflectance, the curves were in the similar range of reflectance (%) except glass ionomer. Changes in lightness were low (0.42-1.27), and changes in chroma were 0.26-2.23 for both conditions. These values were different by the kind of materials. The magnitude of the changes in hue angle was the most prominent in both conditions and was significantly different by the illuminants of A and F2 (P< 0.05). The range of color difference was 1.13-3.02 in both conditions.     

两种VITA比色板的色度学比较

目的：对两种VITA比色板的色度范围进行比较分析，并与中国人牙色度范围相比较，以便为临床选色和瓷粉的使用提供指导。方法：选用CIEl976—L^*a^*b^*色度系统，用Minolta CM—2600d分光测色计对两种VITA比色板的色度佰进行测定，对二者的色度范围做了比较分析。结果：与Vita C1assical比色板相比，Vita 3D Master比色片明度值在较低的区域也有分布，a^*增大，使颜色向黄红色调方向移动；b^*也增大，使颜色的饱和度增大。Vita 3D—Master比色板几乎全部涵盖了Vita Classical比色板的明度和饱和度范围。二者与中国人牙色度范围相比较，部缺乏明度较高的色片，Vita 3D Master比色板较Vita C1assical比色板能够更好的覆盖中国人牙色范围，二者的色度范围相加则更有代表性。结论：Vita 3D—Master比色板较Vita Classical比色板颜色分布的范围更符合中国人牙色度范围、排列更合理，为临床准确地选色、配色提供了可靠的依据。     

The linear shade guide design of Vita 3D‐master performs as well as the original design of the Vita 3D‐master

Summary Visual tooth colour assessment by use of the Vita 3D‐Master^® (3D; Vita Zahnfabrik, Bad Säckingen, Germany) is well documented. To improve handling, a new linear arrangement of the shade tabs has been introduced (LG; Linearguide 3D‐Master^®). The purpose of this study was to investigate whether the linear design has an effect on shade matching. Fifty‐six students underwent identical, theoretical and practical training, by use of an Internet learning module [Toothguide Training Software^® (TT)] and a standardised training programme [Toothguide Training Box^® (TTB)]. Each student then matched 30 randomly chosen shade tabs presented in an intra‐oral setting by a standardised device [Toothguide Check Box^® (TCB)]; 15 matches were made using the 3D and 15 using the LG shade guide system, under a daylight lamp (840 matches for each guide). It was recorded to what extent the presented and selected shade tabs, or the lightness group of the tabs, matched, also the needed time for colour matching. The results showed that 35% of perfect matches were observed for the 3D and 32% for the LG. The lightness group was correct in 59% of cases for 3D and 56% for LG. Mean time needed for matching of tabs and lightness group was no different between groups (no significant difference for any assessment). Within the limitations of the study design, the colour assessment with regard to performance and time needed in shade matching was not different with the LG or the 3D. Therefore, the user should choose which shade tab arrangement is more applicable.     

Spectral reflectance and color of dentin ceramics for all-ceramic restorations

OBJECTIVE: The study was conducted to observe the spectral reflectance curves, and evaluate the color coordinates (CIELAB) of VM7 dentin ceramics (VITA, Germany) across the whole 3D-MASTER shade system. METHODS: Three disc samples, 13 mm in diameter and 1.4mm in thickness, were produced for each shade by firing following the manufacturer's instructions. Each fired disc was ground to a thickness of 1.0 mm and both faces were polished. Spectral reflectance data in the visible spectrum under the standard illuminant D65 were collected at 1 nm intervals by using a computer-controlled spectrophotometer. Color coordinates, L*, a*, b*, C*, h, in the three-dimensional CIELAB color space were obtained. RESULTS: (1) Spectral reflectance in the short-wavelength range systematically decreased with increasing chroma number (M1, M2, and M3) when compared within the same value (lightness) group (1M, 2M, 3M, 4M, and 5M). (2) Spectral reflectance decreased systematically across the whole visible spectrum with increasing value group when compared within the same chroma group. (3) A negative relationship was recognized between lightness (L*) and chromaticity index a* (red-green direction). That is, a* coordinate increases from approximately 1 for the 1M1 sample to approximately 13 for the 5M3 sample, the corresponding lightness systematically decreased from 87 to 69. (4) With increasing a* coordinate, hue angle (h) significantly decreased from 85 degrees for the 1M1 sample to 69 degrees for the 5M3 sample. (5) Lightness apparently increased with increasing hue angle (h) throughout the whole range of the 3D-MASTER shade system. (6) A strong positive relationship between chroma (C*) and chromaticity index b* (yellow-blue direction) was found, demonstrating that the chroma of the present ceramic is mainly controlled by the b* coordinate. SIGNIFICANCE: Systematic variations in spectral reflectance and color coordinates of VM7 dentin were observed throughout the 3D-MASTER shade system and were suggested to be caused by the fine structure of the sample which can interfere with shorter wavelengths in the visible spectrum.     

Conventional visual vs spectrophotometric shade taking for porcelain-fused-to-metal crowns: a clinical comparison

This study tested the shade match of single porcelain-fused-to-metal restorations with the adjacent dentition when the restorations were fabricated according to data from conventional visual shade matching or from a new spectrophotometric system. The samples of a Vita Classic shade guide were measured with the spectrophotometer to determine the CIE L*a*b* color parameters. Three clinicians independently selected the best match to a maxillary right or left incisor needing a restoration in 10 patients. The 10 incisors were then measured using a reflectance spectrophotometer. CIE L*a*b* coordinates were directly recorded on the spectrophotometer's detector area using a standard light source. Resulting conventional and spectrophotometric restorations were tested intraorally for best match with the adjacent incisor using conventional shade matching versus spectrophotometric measuring. Total color difference was calculated, and all groups were statistically analyzed. Initial shade evaluation matched for all three visual shade selections in two cases. In six cases only two evaluators matched, and in the remaining two cases all three visual selections differed. In contrast, in nine of 10 cases all three spectrophotometric shade selections matched. Additionally, in nine of 10 cases delta E values of visually assessed tooth shades were higher than spectrophotometrically assessed delta E values. Resulting delta E values for conventional crowns compared to spectrophotometric crowns were significantly higher. Finally, in nine of 10 cases spectrophotometric crowns were preferred over conventional crowns for definitive cementation when evaluated visually. Spectrophotometric shade analysis and communication can be used efficiently for fabrication of porcelain-fused-to-metal restorations.     

Color stability of a resin-modified glass ionomer cement.

The color stability of a resin-modified glass ionomer cement (Fuji II LC) was investigated over six months using colorimetry. Five shades (A2, A3, A4, B3 and C4) were selected and 10 square specimens (7 mm wide and long, and 1.5 mm deep) were made for each shade using special grit molds. CIE L*, a*, b* color parameters of the specimens were taken at one day, one week, one month, three months and six months. Results were subjected to MANOVA and ANOVA/Scheffe's test at significance level 0.05. The effects of time on color parameters (L*, a*, b* values) were found to be shade dependent. All shades exhibited a decrease in L* values over time. With the exception of shade B3, significant differences in L* values were observed at six months. A general decrease in b* values was also observed but differences among the various time intervals were not significant except for shades A3 and C4. No apparent trends were observed for changes in a* values. For all shades, the largest color change (delta E) was observed between one day and one week. The color stability of the resin-modified glass ionomer investigated was shade dependent. A general decrease in lightness and yellow chroma was observed.     

Effects of colour measuring mode and light source on the colour of shade guides

The objectives of this paper were to evaluate the effects of colour measuring modes [specular component excluded (SCE) versus specular component included (SCI)] and the standard light source (C, A or D65) on the colour of shade guides. After the labial part of shade tabs of two shade guides (Vita and Chromascop) was polished flat up to no. 2400 silicone carbide paper, the colour was measured according to the International Commission on Illumination (CIE)L*a*b* colour scale on a spectrophotometer. In both shade guides, all the average CIE L* values of each shade series, and most of CIE b* values were different depending on the measuring mode (P < 0.01). However, there was no difference in CIE a* values depending on the measuring mode. Colour difference (deltaE*) between the values measured with SCE mode and with SCI mode was 3.21-6.50 in Vita shade guide, 3.22-5.47 in Chromascop shade guide. DeltaE* caused by the difference in light source was very small in Vita shade guide regardless of the measuring mode. In the Vita shade guide, the shade series (A-D) was negatively correlated with CIE L* and CIE a* values measured with SCE mode. In the Chromascop shade guide, the shade series (100-500) was negatively correlated with CIE L* value measured with SCI mode.     

Human-eye versus computerized color matching

This project compared the difference in color matching between human-eye assessment and computerized colorimetry. Fifty dental personnel were asked to color match Vita Lumin shade tabs to seven different randomly arranged test tabs from the Z100 shade guide. All evaluators were blinded to the shades of the test tabs and were asked to match only body shade of the Vita Lumin tab to the middle third or body of each test tab. The results obtained were subsequently computed into L*a*b* values and compared with results obtained by computerized colorimetry. Results indicate that the difference in color matching between human-eye assessment and computerized colorimetry is shade dependent. Discrepancy was significant for b* coordinates for shades A1 and B2 and L* and b* coordinates for shade C4. For all shades evaluated, color difference between human-eye and computerized color matching is perceivable under clinical settings, as delta E values are greater than 3. There is a need for correction factors in the formal specification of the color-matching software due to the discrepancy between human-eye and computerized colorimetric color matching.     

The influence of porcelain layer thickness on the final shade of ceramic restorations

STATEMENT OF PROBLEM: Ceramic restorations should be made of porcelain layers of different opacity, shade, and thickness in order to provide a natural appearance. By means of CAD/CAM layering technology such as CICERO, it is feasible to produce all-ceramic crowns with porcelain layers of predetermined thickness. However, it is not yet known whether changes in thickness of these porcelain layers within the clinically available space can perceivably influence the overall shade of the restoration. PURPOSE: The purpose of this study was to determine, quantitatively, the effect of different thickness ratios of opaque porcelain (OP) and translucent porcelain (TP) layers on the overall shade of all-ceramic specimens. MATERIAL AND METHODS: The CIELAB values of 5 assembled specimens, each consisting of 2 or 3 discs (CORE 0.70 mm/OP--0, 0.25, 0.50, 0.75, or 1.00 mm/TP 1.00, 0.75, 0.50, 0.25, or 0 mm) were determined with a spectrophotometer for the Vita shades A1, A2, and A3. Distilled water was used to attain optical contact between the layers. Black or white backgrounds were used to assess the influence of the background on the final shade. Color differences (DeltaE) between layered specimens were determined. Correlation between the thickness ratio and the L*, a*, and b* values was calculated by 2-tailed Spearman correlation analysis. RESULTS: The results indicated that small changes in OP/TP thickness ratio can perceivably influence the final shade of the layered specimens (DeltaE>1). Redness a* and yellowness b* increased with the thickness of OP for all shades. Redness a* (P<.01 for all shades) correlated more strongly with thickness than yellowness b* (P<.01 for A1 and A3; P<.05 for A2). The lightness (L*) was shade dependent. The correlation (r) between OP/TP thickness and L* was 0.975 (P<.01) for shade A1, 0.700 (not statistically significant) for shade A2, and 0.900 (P<.05) for shade A3. CONCLUSION: Small changes in thickness and shade of opaque and translucent porcelain layers can influence the final shade of the layered porcelain specimen.     

Sphere spectrophotometer versus human evaluation of tooth shade

The purpose of this study was to compare an objective to a subjective method of tooth shade evaluation using the SP78 sphere spectrophotometer and human visual analysis. Twenty extracted fully developed human maxillary teeth had their L* values (lightness) read by the SP78 on day 1 and then again on day 14. Using a blind method, five human evaluators then attempted to match shade tabs from a six-tab experimental Vita shade guide to the same teeth on days 1 and 14. The SP78 L* values read for each tooth were evaluated for a match between those obtained on day 1 and those read on day 14. The results of human evaluation of tooth shade were compared among the evaluators and then between themselves over time. Finally, the ability of human evaluators to match tooth shade was compared with the results obtained with the SP78. The SP78 reproduced L* readings within the standard error of the machine (< or = 1.0) in 16 of 20 (80%) teeth. In contrast, interevaluator agreement expressed as majority agreement (3, 4, or 5 of 5 evaluators agreeing) was only 10 of 20 (50%) teeth on day 1 and 13 of 20 (65%) teeth on day 14. Intraevaluator agreement over the experimental period ranged from 20 to 60%. The results of this study confirm that human evaluation of tooth shade is unreliable and that the SP78 sphere spectrophotometer can provide a more predictable and accurate method of evaluating tooth shade in vitro. This finding opens up a new avenue of investigation for testing the effectiveness of materials and techniques in bleaching discolored teeth.     

带金属底冠定制比色板的制作及其颜色特征

目的：探讨带金属底冠定制比色板的制作方法对其颜色特征的影响。方法：以右侧上颌中切牙为模型,按照临床金属融附烤瓷全冠的制作要求,制作与VITAPAN比色板颜色相对应的16色带金属基底的定制比色板标本,采用PR-650型光谱扫描色度仪,对上不同瓷层后的比色片进行颜色测量。结果：上釉完成后的比色片与上遮色瓷时的比色片进行比较,发现L^＊值呈下降趋势,a^＊、b^＊值呈上升的趋势。从上遮色瓷到上体瓷的过程中,比色片的L^＊值明显下降,而a^＊、b^＊值明显增加;随着釉瓷和透明瓷厚度的增加,L^＊、a^＊和b^＊值均稍有减小;上釉可增加比色片的明亮度。结论：金瓷修复体中各瓷层对修复体颜色都会产生一定影响,并且其影响作用各不相同。     

Reliability of shade selection using an intraoral spectrophotometer

In this study, we evaluate the accuracy and reproducibility of human tooth shade selection using a digital spectrophotometer. Variability among examiners and illumination conditions were tested for possible influence on measurement reproducibility. Fifteen intact anterior teeth of 15 subjects were evaluated for their shade using a digital spectrophotometer (Crystaleye, Olympus, Tokyo, Japan) by two examiners under the same light conditions representing a dental laboratory situation. Each examiner performed the measurement ten times on the labial surface of each tooth containing three evaluation sides (cervical, body, incisal). Commission International on Illumination color space values for L* (lightness), a* (red/green), and b* (yellow/blue) were obtained from each evaluated side. Examiner 2 repeated the measurements of the same subjects under different light conditions (i.e., a dental unit with a chairside lamp). To describe measurement precision, the mean color difference from the mean metric was used. The computed confidence interval (CI) value 5.228 (4.6598-5.8615) reflected (represented) the validity of the measurements. Least square mean analysis of the values obtained by examiners 1 and 2 or under different illumination conditions revealed no statistically significant differences (CI = 95%). Within the limits of the present study, the accuracy and reproducibility of dental shade selection using the tested spectrophotometer with respect to examiner and illumination conditions reflected the reliability of this device. This study suggests that the tested spectrophotometer can be recommended for the clinical application of shade selection.     

Polymerization color changes of esthetic restoratives

The color changes of three different types of tooth-colored restoratives during polymerization were investigated using colorimetry. L*, a*, b* color parameters of five different shades of Z100 (a mini-filled composite resin), Fuji II LC (a resin-modified glass-ionomer cement), and Dyract (a polyacid-modified composite resin) were taken precure and postcure. The results showed that the restoratives evaluated all underwent color changes during polymerization. The polymerization changes in color parameters were shade and not material dependent. Changes in L* parameter or lightness during polymerization were significant for all material and shade combinations and had the greatest influence on the overall polymerization color change. As the color change was perceivable by the human eye for most shades of materials, the clinical practice of polymerizing some material on, or adjacent to, the undried tooth to confirm shades of esthetic restoratives before restorative procedures is prudent.     

Clinical trial evaluating two peroxide whitening strips used by teenagers

Double-blind clinical research was conducted to compare the clinical response of a thin, concentrated peroxide whitening strip (relative to a marketed control) among a teenage population with preceding safety and efficacy data. Informed consent and child assent was obtained from 48 teens, 13-17 years of age. After baseline measurements were taken, subjects were divded randomly into two groups, one using a thin 10% hydrogen peroxide whitening strip, the other using a 6.5% hydrogen peroxide strip with a thicker gel layer. Strip use was 30 minutes twice per day for 22 days on the maxillary arch, followed by 22 days on the mandibular arch. Efficacy was measured objectively based on L*a*b* color change from digital images taken every 11 days, where L* indicates lightness and b* indicates blue-to-yellow shade. The mean age was 15.1 (+/-1.5) years. Relative to baseline, both strip groups experienced significant (p < 0.0001) color improvement for yellowness (deltab*) and lightness/brightness (deltaL*) beginning at the first visit (Day 11). Continued use resulted in significant color improvement through Day 22. Groups did not differ significantly (p > 0.33) with respect to combined deltab* or deltaL* at end-of-treatment. Tooth sensitivity and oral irritation represented the most common adverse events. No subject discontinued early due to a treatment-related adverse event. Teenagers who used either 10% hydrogen peroxide gel or 6.5% hydrogen peroxide gel whitening strips twice a day for 44 days saw significant tooth whitening without serious adverse events.