ORIGINAL RESEARCH Year : 2022  |  Volume : 13  |  Issue : 4  |  Page : 124-127

Shade Matching of OMNICHROMA Analyzed by Four Digital and Visual Shade Selection Techniques: An In Vitro Study

Abdalwahab M Al-Hadithi1, Mohammed K Gholam2
1 Ministry of Health, Baghdad, Iraq
2 Department of Conservative Dentistry, College of Dentistry, Mustansiriyah University, Baghdad, Iraq

Date of Submission29-Jul-2022Date of Decision23-Aug-2022Date of Acceptance24-Aug-2022Date of Web Publication12-Dec-2022

Correspondence Address:
Abdalwahab M Al-Hadithi
Ministry of Health, Baghdad
Iraq

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/denthyp.denthyp_88_22

Introduction: To evaluate the shade matching of teeth restored with OMNICHROMA using four different teeth shade-selection techniques. Methods: Thirty sound upper first premolar teeth were used. Shade was taken by the VITA Linearguide 3D-MASTER, the VITA Easyshade V, digital photography, and the TRIOS 3 intraoral scanner for the cervical area. Subsequently, a Class V cavity was prepared and filled with an OMNICHROMA filling, and another reading for the shade was taken. Results: Value of ΔE in all groups were significantly higher than the clinically acceptable value (ΔE: 3.7) (P < 0.001). One-way ANOVA measurements showed statistically significant differences among the groups (P < 0.001). Conclusion: OMNICHROMA composite showed some degree of mismatch with the surrounding tooth structure. This in vitro model could not simulate complex oral situation and more clinical studies are necessary.

Keywords: Color, color matching, intra-oral scanner, multi-shade universal composites, optical properties, tooth color

How to cite this article:
Al-Hadithi AM, Gholam MK. Shade Matching of OMNICHROMA Analyzed by Four Digital and Visual Shade Selection Techniques: An In Vitro Study. Dent Hypotheses 2022;13:124-7
How to cite this URL:
Al-Hadithi AM, Gholam MK. Shade Matching of OMNICHROMA Analyzed by Four Digital and Visual Shade Selection Techniques: An In Vitro Study. Dent Hypotheses [serial online] 2022 [cited 2022 Dec 13];13:124-7. Available from: http://www.dentalhypotheses.com/text.asp?2022/13/4/124/363442   Introduction 

Searching for a perfect esthetic material for restoring teeth has given rise to exceptional enhancements in esthetic materials and techniques.[1] Composite restorations have been verified to be fine esthetic and tooth-colored restorative materials of choice for many dentists due to their excellent acceptance by patients and their admirable esthetic properties.[2] Shade matching between the restoration and the surrounding dental structure is how patients evaluate the esthetic treatments.[3] The appearance and color of a tooth is a complex phenomenon consisting of several elements, such as lighting conditions, light scattering, opacity, translucency, gloss, the human eye, and the brain influencing the perception of the shade of a tooth.[4] Over the years, great efforts have been made to improve the dental restorative material’s esthetic properties. To achieve ideal esthetics, restorative material must mimic the natural tooth in translucency, surface texture, color, and long-term color stability.[5] Dental materials that display color-shifting towards the color of the surrounding dental tissues may have a clinical advantage, as this can enhance the esthetic appearance of the restoration, simplify shade matching, lessen the number of shade guide tabs and, to some extent, compensate for color mismatches.[6] OMNICHROMA was the first shade-matching composite, and has recently gained considerable popularity. It has a unique property that is based on “smart chromatic technology.” It is capable of capturing the structural color of its surroundings, which is accomplished by controlling the filler particles size.[7] Several studies were conducted to test whether matching was accomplished by OMNICHROMA, but each study used a different shade detection technique from the others.

The objectives of this study were to evaluate the shade match of OMNICHROMA, a one-shade universal supra-nano-filled (filler %: 79 wt) resin composite with the tooth structure by using different shade detection methods (the VITA Linearguide 3D-MASTER, VITA Easyshade V, digital photography, and the TRIOS 3 intraoral scanner) for the same samples.

  Materials and Methods 

This in vitro study was conducted in the Department of Conservative Dentistry, University of Mustansiriyah/Collage of Dentistry, Baghdad, Iraq, and it was approved by Mustansiriyah University-College of Dentistry Research Ethics Committee with approval number REC103. The outcomes were evaluated by a single blinded examiner.

Thirty sound human maxillary premolar teeth extracted for orthodontic purpose from patients with the age of 18 to 23 years had been used in this study. Cleaning of teeth has been done carefully from any calculus and soft tissue deposits with hand scaler, then teeth were polished by a rubber cup in low-speed handpiece using non-fluoride pumice and then rinsed with water.[8] Teeth were positioned for 48 h in 0.1% Thymol solution (BDH chemical Ltd., Kingston, UK) at room temperature to constrain fungal and bacterial growth.[9] Each sample was inserted into a cubical rubber mould that was specially fabricated and that contained cold-cure acrylic (Shanghai New Century Dental Materials Co., Ltd., Shanghai, China) by using a dental surveyor (Paraline Dentaurum, Ispringen, Germany).

Four types of teeth shade-selection techniques were used including the VITA Linearguide 3D-MASTER (VITA Zahnfabrik H. Rauter GmbH & Co., Sackingen, Germany), VITA Easyshade V (VITA Zahnfabrik H. Rauter GmbH & Co., Sackingen, Germany), digital photography (Nikon, Tokyo, Japan), and the TRIOS 3 intraoral scanner (3shape, Copenhagen, Denmark).

All samples were stored in distilled water so that all the shade selection techniques could be conducted while the teeth were wet.

VITA 3D-MASTER linear shade guide

Shade matching was carried out under balanced lighting (daylight between 11 a.m. and 2 p.m.) and at a distance of 10 in., viewed at eye level, so that the most color-sensitive part of the operator’s retina is used. First, the degree of lightness was taken by the value VITA 3D-MASTER linear shade guide by comparing the shade tabs with the natural tooth. The value linear shade guide contains six group levels between 0 and 5 that best correspond to tooth lightness. This value guide consists of M2 of all shades, which are considered the middle chroma and neutral hue. Based on the first preselection, the corresponding VITA Chroma/Hue guide 3D-MASTER level (0/1, 2, 3, 4, or 5) is taken out of the acrylic box and the chroma and hue are determined. After selecting the tab, it is transferred to the CIELAB value by using conversion table in which Shade Guides measured with spectroradiometer with 45° illumination and 0° observer without an aperture.[10]

VITA Easyshade V digital spectrophotometer

The Easyshade V was adjusted and calibrated according to the manufacturer’s instructions and was supported by a special holder in the dental surveyor. Its tip was in contact with the tooth surface perpendicular to the cervical area.[11] Three measurements were taken for each sample, and the mean of these measurements was considered. All results from the Easyshade V were in CIELAB values.

Digital photography

Digital photographs were acquired by using a digital camera (Nikon 5600) equipped with a 105-mm lens (EF 105 mm f/2.8L Macro, Sigma), ring flash, and polarized filter. Camera stabilization was accomplished by mounting a floor tripod in a standard position. All photographs were taken with standardized parameters: exposure was 1/125 s, distance was 15 cm, ISO was 200, f-stop was 25, focusing was 1:1 in RAW format. A grey reference card (PhotoMed International, Van Nuys, California, USA) was used for white balance setting and images were transferred to a computer to be analyzed for color matching. The digital image files were opened in the Adobe Photoshop Lightroom program. The white balance and the image calibration were conducted according to the grey reference card.[12]

Intraoral scanner

Before taking the scan, the TRIOS 3 intraoral scanner was calibrated. Subsequently, the scan was conducted according to the manufacturer’s recommendations, and the result, which was translated to CIELAB values according to the conversion table, was obtained in the 3D-MASTER.

Cavity preparation

A dental surveyor specially modified for this study was used for the preparation of all tooth samples. Class V cavities of 4-mm width, 2-mm length, and 1.5-mm depth were prepared 1-mm coronal to cementoenamel junction. The cavities were rinsed with water and air-dried. Next, they were acid-etched for 20 s with 37% phosphoric acid gel and then rinsed and dried gently. PALFIQUE Bond (Tokuyama Dental, Tokyo, Japan) was applied, and the cavities were light-cured for 20 s in accordance with the manufacturer’s instructions. OMNICHROMA composite (Tokuyama Dental, Tokyo, Japan) was packed in the cavities using a non-stick coating instrument. The restoration was then covered with celluloid strip to minimize the oxygen inhibition layer and to obtain the smoothest possible surface; after this, it was light-cured (radii plus, SDI, Bayswater, Australia) for 40 s. The filling was finished and polished using OptiDisc finishing and polishing Kit (Kerr, Orange, California, USA), which includes an extra coarse disk for contouring, a course/medium disk for finishing, a fine disk for polishing, and an extra-fine disk for high-gloss polishing.[13]

Teeth shade second measurements

All four shade measuring methods were repeated for the teeth with OMNICHROMA restorations and were checked to determine how they match the surrounding tooth structure. The second CIELAB values from this second measuring were obtained to determine the ΔE using the equation

[INLINE:1]

Statistical analysis

One sample student’s t-test, one-way ANOVA, and Tukey post hoc test were used to analyze results by a blinded data analyst using the Python 3.10.4 (The Python Software Foundation, www.python.org).

  Results 

The one sample student’s t-test compares the means of sample data to a known clinically acceptable value (ΔE: 3.7).[14] Value of ΔE in all groups were significantly higher than the clinically acceptable value (P < 0.001). Statistical testing of ΔE among groups was conducted using one-way ANOVA statistic, which showed significant differences among the groups (P < 0.001) [Figure 1].

Figure 1 Box and whisker plot showed results of the ΔE related to the four study groups. P values showed results related to post hoc comparisons using the Tukey method.

Click here to view

  Discussion 

ΔE can be expressed as an acceptability threshold (AT) and perceptibility threshold (PT). The AT is the magnitude of color difference that is acceptable for esthetic outcomes, while the PT is the visually detectable color difference. Some studies have reported that, in a clinical situation, the human eye cannot detect color differences unless the ΔE attains a value of 3.3.[15] However, for Khashayar et al.,[16] PT of ΔE = 1 and AT of ΔE = 3.7 are preferred. Hence, when the ΔE between a filling and tooth structure is below 3.7, it can be said that there is a good shade match between this filling and the tooth structure, and when the ΔE is above 3.7, there will be a mismatch between this filling and the tooth structure.

The results of this study revealed that the ΔEs between the tooth and the OMNICHROMA filling using all methods were all greater than the clinically acceptable value (ΔE: 3.7). For digital photography, the ΔE was 4.721, which was the lowest ΔE compared to the other methods. For the VITA 3D-MASTER, ΔE was 5.135, and for TRIOS 3, ΔE was 13.638. The largest ΔE was generated by the Easyshade V, which was 14.941. Because of these high ΔE results between the OMNICHROMA composite fillings and the teeth, it can be said that there is a difference in shade for this composite filling, and statistically it is significant for all methods compared to the clinically acceptable value of 3.7. The TRIOS 3 and Easyshade V are the most significant, followed by digital photography and the VITA Linearguide 3D-MASTER. The results of this study demonstrated a mismatch between the OMNICHROMA and the teeth due to the high ΔE results, which agrees with that reported by Morsy et al.,[13] who showed a mean ΔE of 9.89.

Our study revealed disagreements with the results reported by Alhamdan et al.,[17] which reported a ΔE of 2.39 for the C3 samples, 3.24 for the A3 samples, and 3.41 for the B2 samples. This disagreement may be related to the use of acrylic teeth rather than natural extracted teeth. Also, Saegusa et al.,[18] reported acceptable color matching for OMNICHROMA using artificial teeth.

Readers must note this is an in vitro study. With respect to the limitations of in vitro models, our study could not simulate complex oral situation and more clinical studies are necessary.

Acknowledgement

The authors would like to thank Mustansiriyah University (www. uomustasiryah.edu.iq), Baghdad-Iraq, for its support in the present work.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 

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  [Figure 1]