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Keywords:

  • Anterior composite restorations;
  • Class IV;
  • colour integration;
  • spectrophotometry;
  • L*a*b*

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. References

Background:  This aim of this study was to compare traditional visual appreciation with spectrophotometry to evaluate the optical integration of anterior composite restorations.

Methods:  Eleven restorations were evaluated in eight patients receiving dental treatment at fourth and fifth year student clinics at the dental school of the University of Geneva, Switzerland. Colour integration of completed restorations was assessed by visual observation according to USPHS criteria and spectrophotometric analysis; both methods were then compared.

Results:  A mean ΔE of 1.1 (range 0.7 to 1.7) corresponded to an optimal visual integration between natural tooth and restoration (alpha score) while a mean ΔE of 3.3 (range 2.6 to 3.8) corresponded to clinically ‘non-acceptable’ visual integration (charlie score). Restorations scored as ‘bravo’, corresponded to a suboptimal but not disturbing visual integration, had a mean ΔE of 2. L* and b* values present at the bevel area and into the composite bulk tended to be lower than that of the natural tooth while a* composite values were slightly higher.

Conclusions:  The spectrophotometric method employed in this pilot study has confirmed the published range of ΔE (global difference of L*a*b* values) corresponding to clinically ‘optimal’, ‘acceptable’ and ‘unacceptable’ colour integration.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. References

Modern resin composites have the potential to reproduce the natural tooth’s appearance and constitutes an excellent aesthetic and conservative alternative to laboratory made restorations, such as crowns and ceramic veneers.1–3 In addition, this treatment option allows for a reduction of treatment cost and duration. However, it can be considered successful from the patient’s perspective only if good colour integration is achieved. This major parameter can be evaluated using qualitative or quantitative methods. Qualitative methods imply a visual evaluation using USPHS criteria4 (with or without photographic documentation) or resin/ceramic references tabs. This approach is based on human visual evaluation and implies a lack of precision and possible bias.5,6 Quantitative methods include colorimetry and spectrophotometry, which are more reliable and not operator dependent.7–11 The later methods were extensively used to compare full prosthetic restorations to natural teeth; however, it was only scarcely applied to appreciate the optical integration of partial composite restorations with surrounding, natural tissues.12

Spectrophotometry has another advantage in allowing full, sectional or localized colour analysis, which makes possible an evaluation of colour integration in different tooth areas,13,14 i.e. cervical, medium and incisal. In addition, measurements can be made to analyse optical transition between teeth and restorations. This would be of particular interest to evaluate the aesthetic transition around composite fillings, which is known to be a problematic area.15,16

The ‘Natural Layering Concept’ has been introduced to improve the aesthetic integration of direct composite restorations and at the same time to make the technique more predictable, by reducing the number of layers (only two layers: dentine and enamel) applied.2

The aims of this study were to: (1) evaluate the aesthetic integration of Class IV direct composite restorations performed with the Natural Layering Concept in vivo in an undergraduate environment; (2) tentatively correlate the visual and spectrophotometric colour integration of the same restorations and establish within which numerical interval (ΔE) those restorations can be considered aesthetically acceptable; and (3) analyse the aesthetic transition of the same restorations (from tooth substrate to bevel area to restoration main surface).

Materials and methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. References

Subjects who participated in the study were randomly chosen among patients receiving dental treatment at fourth and fifth year student clinics at the dental school of the University of Geneva, Switzerland. Each enrolled patient had given verbal informed consent for additional spectrophotometric and photographic analysis of their restored anterior upper tooth, following the method proposed by Ardu and co-workers.6 Patients included in this study had to receive one, possibly two Class IV direct composite restorations (involving no more than half of the incisal edge) on one of their four anterior upper incisors. A total of 11 Class IV restorations were evaluated in eight patients aged between 18 and 70. Only vital teeth were selected which had no malformation, fissures or other visible intrinsic or extrinsic discolouration.

Prior to each measurement, the patient’s teeth were cleaned with a prophylaxis paste (Depurdent, Dr. Wild & Co. AG, Basel, Switzerland) and rinsed with water spray to avoid bias due to extrinsic colourations. Care was taken not to dehydrate the teeth before measurement to avoid changes in tooth optical characteristics (chroma, brightness, translucency and opalescence) due to a change in enamel surface moisture.

The study design was not reviewed by the dental school’s ethics committee because dental restorations under evaluation are part of the usual restorative therapy employed in the undergraduate teaching programme at the University of Geneva.

Tooth shade determination by shade tab selection

A digital intraoral photograph (Nikon D500, Miyagi, Japan) of the four anterior front teeth was taken with a macro lens (105 mm Macro Lens, Sigma, Japan) and a macro flash (EM140DG Flash, Nikon, Japan) before and one week after the end of the treatment as proof of the clinical evaluation. The optimal dentine and enamel shades of the restorative composite (Miris2, Coltene Whaledent, Altsätten, Switzerland) were selected using a proprietary dual shade guide system, following the manufacturer’s instructions and the Natural Layering Concept.2 This involved three steps: (1) selection of dentine chroma with the dentine shade tab being placed next to the tooth collar; (2) visual selection of the appropriate enamel tint and translucency; and (3) confirmation of both dentine and enamel choice with the combination of two shade samples, placed with the shade guide incisal edge against natural tooth incisal edge. Shade was registered by each operator (student) and confirmed by the supervising assistant. Seven student-operators participated in this multi-operator pilot study.

Colour measurements

In this in vivo study, a double evaluation was performed: visual, based on the optical USPHS scale which had been confirmed by two different operators4 (dentist plus student) who have been previously ‘calibrated’ according to the methodology proposed by Hickel et al.17 and a spectrophotometric device using a calibrated reflectance spectrophotometer (SpectroShade, Handy Dental Type 713000, Serial No. HDL0090, MHT, Arbizzano di Negar, Verona, Italy). Using this device, CIE 1976 L*a*b* measurements of the restored and the corresponding natural surface located on the other tooth half of each subject were performed without any background. The device has a built-in aiming mechanism that enables reproducible positioning perpendicular to the facial tooth surface to ensure equal measurement conditions for all teeth evaluated. The device was equipped with a D65 light source (6500°K); this light is splinted in order to have each tooth illuminated simultaneously from two sides at a 45° angle. The reflected light was directed at 0° on the system’s two detector areas (18 mm × 13 mm). One detector was a colour CCD chip that generates a colour video image. The other CCD detector recorded spectrophotometric data. Polarization filters were used to eliminate surface gloss. The data are stored in a proprietary image file format which was used to create detailed CIE L*a*b* data.

Spectrophotometric measurements

Colour measurements were performed one week after the final polishing of the restoration over the entire buccal surface of each restored tooth so that CIE L*a*b* data could be further analysed. This served to: (1) compare the entire restoration surface (integration measurement) to the contralateral tooth half (Fig. 1a); and (2) evaluate in each tooth/restoration third (cervical, medium and incisal) the transition from restoration to natural tooth surface (Fig. 1b) and from bevel and to natural tooth (Fig. 1c), using a spot measurement approach (over 5 pixels).

image

Figure 1.  Spectrophotometric measurements. (a) = surface integration; (b) = spot measurements for tooth/restoration comparison over 3 thirds; (c) = spot measurement for tooth/bevel comparison over 3 thirds.

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Colour differences were mathematically calculated as ΔE values, using MHT analysis software (SpectroShade, Dental Software Version 2.41, MHT) and according to the following formula:

  • image

Statistical analysis

Spectrophotometric values were distributed into three subgroups according to visual observation score (alpha, bravo and charlie). Non-parametric tests (Kruskal–Wallis) were then performed to explore possible differences between those subgroups for each evaluation method (integration and spot measurements for restoration-natural tooth and bevel-natural tooth at cervical, medium and incisal thirds). To ascertain the concordance between ΔE values and their respective visual scores, a Kendall’s tau coefficient of concordance was applied.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. References

Visual observations

Summarized results of visual observations are presented in Tables 1A to 1C according to the three measuring methods described in Fig. 1. When surface integration area was considered (composite restoration being compared to the natural tooth half), four restorations were scored as alpha (optimal colour match), 1 as bravo (acceptable colour match) and 6 as charlie (‘non-acceptable’ colour match). When the composite-natural tooth spot measurement was performed over the three different thirds of the tooth, four segments were scored as alpha, 7 as bravo and 22 as charlie. When the bevel-natural tooth spot measurement was performed over the three thirds of the tooth, 19 segments were scored as alpha, 6 as bravo and 8 as charlie.

Table 1A.   Visual scores of the entire restoration related to ΔE as obtained with spectrophotometric analysis (with clinical case reference)
 AlphaBravoCharlie
 1.3 (3)2 (11)3.6 (2)
0.7 (7) 3.9 (5)
1.7 (6) 3.8 (8)
0.7 (4) 3.2 (9)
  2.9 (10)
  2.6 (1)
Mean 1.1 2 3.3
Table 1B.   Visual scores of spot measurements for composite-natural tooth comparison, related to ΔE as obtained with spectrophotometric analysis (with clinical case reference)
 AlphaBravoCharlie
 1.4 (3)1.8 (7 C)5.2 (3 C)
0.8 (5 I)1.9 (10 C)2.7 (5 C)
1.7 (1 M)1.8 (4 M)3.3 (10 I)
0.6 (2 M)1.8 (10 M)3.6 (8 C)
 2 (4 C)2.7 (9 C)
 2.2 (11 C)3 (3 M)
 2.1 (8 M)3.1 (5 M)
  5.3 (6 M)
  3.2 (7 M)
  3.8 (8 M)
  5.4 (1 I)
  2.6 (2 I)
  3.6 (5 I)
  6.4 (6 I)
  2.8 (7 I)
  5.3 (8)
  4.3 (9 I)
  3.3 (6 C)
  3 (11 I)
  2.5 (1 C)
  2.3 (2 C)
  2.4 (11 M)
Mean 1.1 1.9 3.6
Table 1C.   Visual scores of spot measurements for bevel-natural tooth comparison, related to ΔE as obtained with spectrophotometric analysis (with clinical case reference)
 AlphaBravoCharlie
 1.1 (1 I)1.8 (1 M)3.4 (2 C)
1 (5 I)1.9 (4 I)3.8 (6 M)
1.1 (6 I)1.9 (1 C)4.9 (6 C)
1.2 (7 I)2 (9 C)2.9 (7 M)
1.4 (8 I)2.2 (10 C)2.9 (7 C)
1.6 (9 I)2.2 (11 C)2.3 (8 C)
1.2 (10 I) 2.4 (3 I)
1.6 (11 I) 2.4 (3 M)
1.2 (11 M)  
0.9 (10 M)  
1.4 (9 M)  
1.1 (8 M)  
0.9 (5 M)  
0.7 (4 M)  
0.6 (2 M)  
0.6 (3 C)  
1.4 (4 C)  
0.7 (5 C)  
1(2 I)  
Mean 1.1 2 3.13

Spectrophotometric evaluation

Table 2 describes the typical quantitative colour evaluation presented in this report; intraoral photography served only as a reference (Fig. 2).

Table 2.   Quantitative colour evaluation of case no. 11 (Fig. 2)
 Tooth surfaceComposite surfaceDiff t-c
L*61.961.970.08
a*3.422.440.9
b*15.6113.831.74 ΔE 1.97
 toothbevelDiff t-bcompositeDiff t-c
CERVICAL
 L*64.2763.830.4463.79−0.47
 a*4.324.3203.840.48
 b*17.4415.93−1.51 ΔE 1.5815.382.06 Δ2.17
MIDDLE
 L*56.9666.640.566.810.85
 a*3.332.750.582.90.43
 b*18.2317.350.88 ΔE 1.1716.032.2 ΔE 2.4
INCISAL
 L*57.8458.220.3858.360.52
 a*4.03.690.313.440.56
 b*17.7515.632.12 ΔE 2.1714.92.85 ΔE 2.95
image

Figure 2.  Typical restoration to which the pilot colour evaluation method was applied (case no. 11)

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When the total surface integration area was considered (composite restoration area being compared to the corresponding natural surface located on the other tooth half) spectrophotometric values for USPHS alpha score ranged from 0.7 to 1.7 (mean 1.1), for bravo score was 2 (1 sample only) and for charlie score ranged from 2.6 to 3.8 (mean 3.3) (Table 3A).

Table 3A.   Summary of surface integration for the 11 restored teeth (composite total restoration area compared to the contralateral surface, located on the other tooth half)
 1234567891011meanSD
ToothL*62.368.059.662.253.356.470.363.962.861.661.962.04.7
a*2.71.02.54.75.17.51.53.13.64.43.43.61.8
b*15.517.915.315.916.122.011.715.916.016.115.616.22.4
CompositeL*62.364.060.262.954.055.470.961.665.262.262.061.94.5
a*2.73.02.64.74.96.31.11.81.83.22.43.11.6
b*15.520.014.216.620.021.911.813.414.314.013.816.03.2
ΔT-CL*2.2−4.00.70.00.7−1.00.5−1.32.30.70.10.11.6
a*−0.32.00.10.0−0.2−1.20.5−1.2−1.81.10.90.01.1
b*−1.31.9−1.10.73.8−0.80.1−2.5−1.72.11.70.31.9
ΔE2.63.51.30.73.91.70.73.83.22.42.02.31.2

When the composite-natural tooth comparison and analysis was performed over the three different tooth’s thirds, spectrophotometric values for alpha score ranged from 0.6 to 1.7 (mean 1.1), for bravo score ranged from 1.8 to 2.2 (mean 1.9), and for charlie score ranged from 2.3 to 6.4 (mean 3.6) (Tables 3B–3D).

Table 3B.   Summary of spot measurements made in the cervical third for the 11 restored teeth (T = Tooth, C = Composite, B = Bevel)
 1234567891011meanSD
ToothL*65.067.367.361.756.057.071.864.867.267.064.364.54.7
a*4.53.53.47.36.68.75.13.95.45.44.35.31.7
b*20.020.019.920.121.028.417.018.317.619.017.419.93.1
BevelL*64.066.765.160.755.056.770.864.465.866.063.863.64.5
a*5.03.73.88.16.68.75.44.35.55.54.35.51.7
b*20.021.019.018.721.427.417.517.016.818.415.919.33.2
CompositeL*66.066.063.459.953.858.269.965.865.765.963.863.54.5
a*3.74.54.68.07.07.45.83.45.05.33.85.31.5
b*18.021.718.919.722.525.616.814.815.317.515.418.73.4
ΔT-CL*1.0−1.21−4.9−1.8−2.21.10.93.4−1.61.1−0.5−0.42.2
a*−1.01.11.30.60.4−1.30.7−0.5−0.40.10.50.10.8
b*−2.01.6−1.0−0.41.5−2.80.4−3.4−2.21.52.1−0.41.9
ΔT-BL*−1.0−0.6−2.2−0.2−0.9−0.3−1.0−0.3−1.41.00.4−0.60.9
a*0.50.20.40.80.00.00.40.40.10.00.00.20.2
b*0.40.8−0.9−1.40.4−1.10.5−1.3−0.70.6−1.5−0.40.9
ΔE T-B1.11.02.41.91.01.11.21.41.61.21.61.40.4
ΔE T-C2.52.35.22.02.73.31.83.62.71.92.22.71.0
Table 3C.   Summary of spot measurements made in the medium third, for the 11 restored teeth (T = Tooth, C = Composite, B = Bevel)
 1234567891011meanSD
ToothL*66.069.064.464.057.656.073.565.567.067.757.064.45.4
a*3.01.42.04.74.58.52.73.13.03.43.33.61.9
b*18.019.317.016.221.425.114.617.519.617.218.218.52.8
BevelL*66.069.563.264.056.858.473.464.467.167.466.665.24.7
a*3.01.32.24.34.36.62.52.93.23.22.73.31.4
b*18.019.314.916.821.122.514.917.818.316.317.317.92.4
CompositeL*66.069.363.465.755.857.870.366.568.767.066.865.24.6
a*1.91.51.94.25.05.82.32.12.53.12.93.01.3
b*19.018.914.116.318.920.711.916.416.215.516.016.72.4
ΔT-CL*−1.00.3−1.11.7−1.31.4−3.21.01.70.70.80.11.5
a*−1.00.1−0.1−0.50.5−2.60.4−1.0−0.50.30.4−0.40.9
b*1.1−4.3−2.90.02.5−4.4−2.6−1.1−3.41.72.21.02.6
ΔT-BL*1.70.6−1.20.0−0.82.0−0.1−1.10.10.30.50.20.9
a*0.0−0.10.2−0.4−0.21.8−0.2−0.10.20.20.60.20.6
b*0.00.0−2.00.6−0.3−2.60.30.3−1.40.90.9−0.31.2
ΔE T-B1.80.62.40.70.93.82.91.11.41.01.21.61.01.8
ΔE T-C1.70.63.01.83.15.33.22.13.81.82.42.61.21.7
Table 3D.   Summary of spot measurements made in the incisal third for the 11 restored teeth (T = Tooth, C = Composite, B = Bevel)
 1234567891011meanSD
ToothL*63.062.959.061.851.253.365.960.959.958.057.859.44.1
a*0.62.32.13.75.37.10.74.02.63.74.03.31.7
b*11.019.212.013.44.627.67.620.017.115.417.715.16.2
BevelL*63.064.559.662.551.953.767.360.261.158.158.260.04.4
a*1.42.01.92.95.36.30.93.22.33.23.73.01.5
b*13.016.212.214.411.822.810.118.115.513.215.614.83.4
CompositeL*67.063.060.064.751.653.267.162.863.157.358.460.84.7
a*3.51.92.22.24.66.10.83.01.52.93.42.91.5
b*12.016.611.014.911.421.310.115.214.412.314.914.03.1
ΔT-CL*4.50.10.92.90.40.01.21.93.20.70.51.51.1
a*2.9−0.40.1−1.4−0.6−1.10.0−1.0−1.00.80.6−0.10.7
b*0.9−2.6−1.01.5−0.2−6.32.5−4.5−2.73.12.8−0.63.1
ΔT-BL*0.51.60.50.751.60.51.4−0.71.20.10.45.215.3
a*0.7−0.3−0.2−0.84.60.80.10.7−0.30.50.30.61.4
b*1.6−2.90.21.011.4−4.82.5−2.0−1.62.22.10.94.2
ΔE T-B1.93.40.61.40.74.92.92.22.02.32.22.31.21.9
ΔE T-C5.42.61.43.60.86.42.85.34.33.32.93.51.65.4

When the composite bevel-natural tooth comparison and analysis was performed over the three different tooth’s third, spectrophotometric values for alpha score ranged from 0.6 to 1.4 (mean 1.1), for bravo score ranged from 1.8 to 2.2 (mean 2), and for charlie score ranged from 2.3 to 4.9 (mean 3.1) (Tables 3B–3D).

The Kruskal–Wallis test, comparing spectrophotometric results of the three subgroups for surface integration and spot measurements, gave the following p-values respectively: 0.0184 (Table 1A), <0.0001 (Table 1B) and <0.0001 (Table 1C). Therefore, the statistical test revealed that there were significant differences between the ΔE average values of the three subgroups. The highest significance was found for spot measurements for composite-natural tooth and for bevel-natural tooth comparison.

The concordances between optical and spectrophotometric scores (Kendall’s tau coefficients of concordance) (Tables 4A–4C) showed significant values for each group, with p-values of 2% for surface integration (Table 4A) and below 1% for third and spot measurements (Tables 4B and 4C).

Table 4A.   Kendall’s tau correlation: 0.6548 (p-value < 0.02) for the entire restoration evaluation
 SubgroupΔE based classificationTotals
A (ΔE ≤ 1.1)B (1.1 < ΔE ≤ 3.3)C (ΔE > 3.3)
Visual classificationAlpha22 4
Bravo 1 1
Charlie 336
 Totals26311
Table 4B.   Kendall’s tau correlation: 0.5246 (p-value < 0.01) for restoration-natural tooth (spot measurements)
 SubgroupΔE based classificationTotals
A (ΔE ≤ 1.1)B (1.1 < ΔE ≤ 3.3)C (ΔE > 3.3)
Visual classificationAlpha22 4
Bravo 7 7
Charlie 13922
 Totals222933
Table 4C.   Kendall’s tau correlation: 0.6397 (p-value < 0.01) for bevel-natural tooth (spot measurements)
 SubgroupΔE based classificationTotals
A (ΔE ≤ 1.1)B (1.1 < ΔE ≤ 3.3)C (ΔE > 3.3)
Visual classificationAlpha118 19
Bravo 6 6
Charlie 538
 Totals1119333

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. References

Spectrophotometric devices are useful tools which provide precise and reproducible colour measurements in vitro and in vivo as published in the literature.5,6,8,18–21 However, little is known about the correlation between visual integration of composite restorations and spectrophotometric values. In this study, the authors visually evaluated the aesthetic result of Class IV fillings in the upper anterior area and compared the USPHS colour scores with their respective spectrophotometric evaluation.

The SpectroShade from MHT is a device that records the entire tooth surface, making it possible to analyse the full or partial tooth and restoration surfaces/locations. Furthermore, taking an intraoral colour measurement takes into consideration all the clinical factors that may influence the aesthetic appearance of the teeth and restorations, such as the pulpal blood supply and the surrounding gingival tissues, which by scattering phenomenon can influence tooth colour perception.5 No coloured background for both visual and spectrophotometric analysis was used in this study. This was done to simulate the clinical situation that is common during speaking or smiling, i.e. when no overlap between upper and lower teeth is present.

In this way a direct comparison between human vision and spectrophotometry could be performed and the degree of correlation between both ‘colour evaluation methods’ could be established. So far it has been claimed that a ΔE (colour difference) higher than 1.1 is visually perceptible and 3.3 aesthetically disturbing.22,23 According to the results of the total surface area integration as well as evaluations for each third, the values proposed in the literature are substantially confirmed. In this study, for the total surface integration, a mean ΔE of 1.1 (range 0.7 to 1.7) corresponded to an optimal surface integration between natural tooth and restoration (alpha score) while a mean ΔE of 3.3 (range 2.6 and 3.8) corresponded to clinically ‘non-acceptable’ visual integration (charlie score). Restorations scored as ‘bravo’, corresponding to a suboptimal but not disturbing visual integration, had a mean ΔE of 2.

Within the limitations of this in vivo pilot study, the overall visual scores and spectrophotometrical results demonstrated the satisfactory aesthetic outcomes of the Class IV restorative technique which suggests that direct adhesive restorative techniques provide aesthetically satisfactory results. However, the aesthetic transition from restoration to tooth over the bevel remains critical.

Furthermore, the agreement between optical evaluation and spectrophotometric values proved to be statistically significant and demonstrated, despite the limited sample size, a good correlation. From a mathematical and theoretical standpoint and for this specific set of restorations, the following ΔE visual score boundaries –ΔE alpha below 1.7, ΔE bravo between 1.7 and 2.2, and ΔE charlie above 2.2 – which only represents a slight alteration of published borders, would provide a total (100%) correlation between both evaluation methods.

Nonetheless, these results should be viewed with caution due to the low number of clinical cases and restricted number of operators. Future randomized double blind in vivo clinical studies with higher number of restorations (Class IV as well as Class III) and operators are needed to confirm the results obtained in this pilot study. In addition, as no spectrophotometric device (including the one used in this study) has integrated values for composite systems, it cannot serve to select colour in everyday practice as commonly done for ceramic systems. The proposed method then remains useful for clinical research only.

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. References

This pilot study has compared a visual approach to spectrophotometry in order to evaluate the optical integration of anterior composite restorations. One of the main drawbacks of the visual method still used routinely in many clinical studies is its ‘subjective’ dimension leading to a semi-quantitative rating of restoration aesthetic integration. The spectrophotometric method employed in this study has: (1) confirmed the range of ΔE (global difference in L*a*b* values) corresponding to clinically ‘optimal’, ‘acceptable’ and ‘unacceptable’ colour integration published in the literature; (2) demonstrated statistically the value of spectrophotometry for further clinical evaluations of tooth coloured restorations and its satisfactory correlation with visual evaluation; and (3) underlined the still aesthetic integration-transition of Class III and IV composite fillings at the tooth-restoration interface. These conclusions need to be confirmed by a multi-operator study and a larger number of samples.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. References
  • 1
    Dietschi D. Layering concepts in anterior composite restorations. J Adhes Dent2001;3:7180.
  • 2
    Dietschi D, Ardu S, Krejci I. A new shading concept based on natural tooth color applied to direct composite restorations. Quintessence Int2006;37:91102.
  • 3
    Ardu S, Krejci I. Biomimetic direct composite stratification technique for the restoration of anterior teeth. Quintessence Int2006;37:167174.
  • 4
    Ryge G, Snyder M. Evaluating the clinical quality of restorations. J Am Dent Assoc1973;87:369377.
  • 5
    Paul S, Peter A, Pietrobon N, Hämmerle CH. Visual and spectrophotometric shade analysis of human teeth. J Dent Res2002;81:578582.
  • 6
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