A comparison of conventional visual and spectrophotometric shade taking by trained and untrained dental students

Effectiveness of Lighting Conditions on Shade Matching Accuracy Among Dental Students

Background: In prosthodontics, achieving esthetic success requires precise shade matching of restorations to natural teeth. This study evaluated the shade-matching abilities of fourth-year dental students using different tools and conditions in laboratory (LB) and clinical (CL) settings. Methods: In the LB setting, students matched blinded shade tabs to the VITA classical shade guide under natural daylight (ND), artificial light (AL), and a polarized filter (PF). In the CL setting, they determined the shades of patients' central incisors using the same conditions. Participants also completed a questionnaire about their experience. Results: Quantitative analysis showed better shade matching in the LB setting, particularly with the PF (52% correct), compared to ND (50%) and AL (43%). In the CL setting, overall accuracy dropped to 32% across all conditions. No results were statistically significant. Qualitative feedback revealed that students found the spectrophotometer to have improved their accuracy and reliability compared to the ND and AL conditions. Conclusions: This study highlights the importance of incorporating technology as a validation tool in dental practice. Leveraging tools like spectrophotometers may enhance shade-matching accuracy, streamline processes, and improve patient satisfaction while balancing traditional methods with technological advancements.

The colour stability of 3D-printed, non-invasive restorations after 24 months in vivo - esthetically pleasing or not?

OBJECTIVES

The aim of the present prospective study was to evaluate the colour stability of 3D-printed non-invasive restorations after 24 months in vivo.

METHODS

The study included 29 patients, who received 3D-printed restorations made of a computer-aided design (CAD) / computer aided-manufacturing (CAM) hybrid material (n = 354). Restoration colour of 190 restorations was measured using a spectrophotometer. By applying the CIELAB system, *L (lightness), a* (red-green) and b* (blue-yellow) values were recorded. An evaluation of the colour differences (ΔE) after 6, 12 and 24 months was conducted.

RESULTS

Analysis of colour differences of 3D-printed restorations showed continuous discolouration of the restorations. After one year 34 % and after two years 18 % of the restorations were rated alpha or bravo, indicating no or hardly visible colour change. After two years, 54 % of the evaluated restorations yielded a colour difference with ΔE > 6.8 (delta). More than 82 % of the evaluated restorations showed values between ΔE 3.8 - 6.8 (charlie) and ΔE ˃ 6.8 (delta) after two years.

CONCLUSIONS

3D-printed non-invasive restorations showed an overall reduced colour stability after 24 months in vivo.

CLINICAL SIGNIFICANCE

The present study provides first clinical data regarding 3D-printed restorations. These restorations are recommended for a wearing time of about 6 months.

Efficacy of a buccal and lingual at-home bleaching protocol-A randomized, split-mouth, single-blind controlled trial

OBJECTIVE

To compare the color change, the risk and intensity of tooth sensitivity (TS), and gingival irritation (GI) of at-home bleaching applied on the buccal surface only or the buccal and lingual surfaces.

MATERIALS AND METHODS

Sixty patients with canines A2 or darker were selected and their superior arches were randomized in two groups: at-home bleaching on the buccal-only or on the buccal and lingual surfaces, with 7.5% hydrogen peroxide, for 1 h daily/2 weeks. The color change was evaluated at baseline, 7, 14 days, and 1 month after bleaching using shade guides scales (ΔSGU) and a spectrophotometer (ΔEAB, ΔE00, and ΔWID). Risk and intensity of TS and GI were recorded daily using visual analogic scale (0-10). Patient satisfaction was evaluated with the orofacial esthetics. Paired t-test, McNemar's, and Wilcoxon signed-rank test were used for data analysis (α = 5%).

RESULTS

Neither the color change nor the risk/intensity of TS was statistically different between groups (p > 0.05). Patient satisfaction increased after bleaching for both groups (p < 0.05).

CONCLUSION

The addition of one contact surface does not result in an increased whitening degree compared to bleaching applied solely on the buccal surface.

CLINICAL SIGNIFICANCE

Understanding the influence of surfaces interacting with the bleaching agent is crucial for comprehending the bleaching mechanism and avoiding unnecessary material expenses. Notably, employing the buccal-only technique is sufficient to achieve the desired efficacy.

Digital Photocolorimetric Analysis of In Vitro Tooth Color Changes

OBJECTIVE

Tooth color matching is challenging, and digital photocolorimetry using eLABor_aid (eLAB) provides objective evaluation through polarized photographs. However, its comparability with spectrophotometry remains unclear.

METHODS AND MATERIALS

Bovine incisor root canals (n=30) were prepared to simulate an incomplete root apex. The teeth were randomly assigned to three groups based on intracanal medication: control (without medication); calcium hydroxide/propylene glycol; and triple-antibiotic paste (n=10 each). Tooth color was assessed using both eLAB and spectrophotometry. Measurements were taken at the crown medio-cervical region on five-time intervals (baseline, 1, 3, 7, and 14 days). Statistical analysis included two-way repeated-measures ANOVA, Sidak post hoc and Pearson's correlation test (α=0.05).

RESULTS

No significant differences were observed between the two methods for either medication or follow-ups (p>0.05). Triple-antibiotic paste exhibited higher color variation (p<0.05). After 7 days, all groups presented significant color changes (p<0.05). Moderate to high correlations (R2 from 0.51 to 0.84, p<0.0001) were found between both methods for all groups at all intervals.

CONCLUSION

The eLAB is a reliable method for detecting tooth color changes, and its results are comparable to spectrophotometry analysis.

Clinical Comparative Study of Shade Measurement Using Two Methods: Dental Guides and Spectrophotometry

Tooth color is a determining factor in the fabrication of dental prostheses. The aim of the present study is to compare two measurement methods used in the field of dentistry: dental guides and spectrophotometry. A total of 2768 natural teeth were measured using the Vita Classical and Vita 3D-Master dental guides (Vita-Zahnfabrik, Bad Säckingen, Germany), as well as a Vita Easyshade Compact spectrophotometer (Vita-Zahnfabrik). The measurements were carried out by one operator under suitable illumination conditions at 5500 degrees Kelvin. The obtained results show that the measurements obtained with the Vita Classical dental guide classifies teeth into the A-B categories, while the spectrophotometer preferentially classifies teeth into the B-C categories. The correlation coefficients obtained with the dental guides ranged from -0.32 to -0.39 (p < 0.01), while those for the spectrophotometer ranged from -0.35 to -0.55 (p < 0.01). Therefore, we can conclude that the spectrophotometer is more reliable and reproducible in its measurements than the dental guides.

A Comparative Study of Shade-Matching Reproducibility Using an Intraoral Scanner and a Spectrophotometer

BACKGROUND

We compared the repeatability of the shade determination of resin composite restorations and acrylic teeth in light and darker shades at baseline and after an aging process through two digital tooth color-matching methods: using a Trios 3Shape intraoral scanner and using a Vita Easyshade Compact spectrophotometer.

MATERIAL AND METHODS

Forty upper central incisor acrylic teeth in the shade A1 (n = 10) and A3 (n = 10) were randomly assigned to be restored with Filtek Bulk Fill in the shade A1 (n = 10) or A3 (n = 10). Subsequently, 20 Class V cavities were prepared in a standardized manner (mesio-distal = 3.0 mm, cervical-occlusal = 2.0 mm, depth = 1.5 mm). Cavities were restored using an universal adhesive system and resin composite in two increments and were light-cured. The shade difference between the resin composite Class V restorations in acrylic teeth of the A1 and A3 shades was evaluated at baseline and after aging. Aging was simulated using ultraviolet light for 120 h. An Easyshade device and an intraoral scanner were used under D65 illumination. Measurements were taken five times, on top of the restoration and on the acrylic teeth, in a randomized manner.

RESULTS

Data analysis was on the calculation of the arithmetic mean for the percentage of repeatability conducted by the Trios scanner and the Easyshade device. There was no statistically significant comparison between the shade measurement devices (p > 0.05). At baseline, the repeatability for both the Trios intraoral scanner and the Vita Easyshade Compact device for artificial teeth in the shades A1 and A3 was 100%. After aging, the trueness recorded by the intraoral scanner and the Easyshade device for artificial teeth in the shade A1 was 80%. For Class V restoration with shade A1, the intraoral scanner recorded 80% trueness and the Easyshade device recorded 60% trueness at baseline. For shade A3, the intraoral scanner recorded 60% trueness and the Easyshade device recorded 60% trueness.

CONCLUSIONS

The intraoral scanner and Easyshade device are reliable for baseline shade selection, but their accuracy decreases after aging, particularly for darker shades.

Comparison of different digital shade selection methodologies in terms of accuracy

PURPOSE

This study aims to evaluate the accuracy of different shade selection techniques and determine the matching success of crown restorations fabricated using digital shade selection techniques.

MATERIALS AND METHODS

Teeth numbers 11 and 21 were prepared on a typodont model. For the #11 tooth, six different crowns were fabricated with randomly selected colors and set as the target crowns. The following four test groups were established: Group C, where the visual shade selection was performed using the Vita 3D Master Shade Guide and the group served as the control; Group Ph, where the shade selection was performed under the guidance of dental photography; Group S, where the shade selection was performed by measuring the target tooth color using a spectrophotometer; and Group I, where the shade selection was performed by scanning the test specimens and target crowns using an intraoral scanner. Based on the test groups, 24 crowns were fabricated using different shade selection techniques. The ΔE values were calculated according to the CIEDE2000 (2:1:1) formula. The collected data were analyzed by means of a one-way analysis of variance.

RESULTS

For the four test groups (Groups C, Ph, S, and I), the following mean ΔE values were obtained: 2.74, 3.62, 2.13, and 3.5, respectively. No significant differences were found among the test groups.

CONCLUSION

Although there was no statistically significant difference among the shade selection techniques, Group S had relatively lower ΔE values. Moreover, according to the test results, the spectrophotometer shade selection technique may provide more successful clinical results.

Visual Versus Digital Color Determination of 3D-Printed Teeth as an Exercise in Dental Students' Education

Visual color determination is part of the daily routine in dental practice. However, it is not a part of dental education so far. The aim of this study was to evaluate whether visual or digital tooth color determination of 3D-printed teeth is a reliable tool for inexperienced dentistry students. Preclinical dental students evaluated eleven 3D-printed, tooth-shaped samples (VarseoSmile Crown plus, BEGO, Bremen, Germany) of different color shades. Visual shade determination using a reference scale (3D-Master Toothguide (3DM_TG), VITA Zahnfabrik, Bad Säckingen, Germany), followed by a digital color determination using a spectrophotometer (VITA Easyshade V, (ES_V), VITA Zahnfabrik), was performed. Color deviation was calculated in the Lab* color space (ΔE00) and converted into CIELAB 2000. The results were evaluated using the Mann-Whitney U test and the Wilcoxon Rank Sum test (α = 0.05). Significant differences between visual and digital color determination were proven (p < 0.001). Visual color determination (3DM_TG) showed a mean deviation (ΔE00 ± 95%CI) of 6.49 ± 0.47. Digital color determination (ES_V) showed significantly lower mean deviations of ΔE00 of 1.44 ± 0.58. Digital tooth color measurement using a spectrophotometer was a more reliable tool for the color determination of 3D-printed teeth for inexperienced dentistry students.

Influence of a gray background and the illuminant on tooth shade selection

STATEMENT OF PROBLEM

Visual shade selection in dentistry may be influenced by factors that include the background color and the illuminant.

PURPOSE

The purpose of this clinical study was to evaluate the influence of using a gray background and a light-correcting device on visual shade selection.

MATERIAL AND METHODS

Two experienced clinicians assessed the incisor color of 30 volunteers using the VITA 3D-MASTER shade guide. Visual analyses were carried out using or not (control) a gray background, with and without (control) a light-correcting device (Smile Lite). Furthermore, the use of a polarizing filter was evaluated. Data from a clinical spectrophotometer were defined as the standard instrumental analysis. The agreement and the similarity (based on the whitening indexes of tabs) were evaluated between instrumental and visual analyses. Statistical testing was conducted through ordinal logistic regression and repeated-measures ANOVA. The Shapiro-Wilk test was used to confirm the data distribution, and homogeneity of variance was assessed with the Levene test (α=.05) RESULTS: The use of Smile Lite resulted in lighter tabs than indicated by the instrumental analysis, and the opposite was observed in its absence. The polarizing filter did not affect the results (P>.05). For similarity, the illuminant improved the results (P<.001). The gray background reduced the differences between visual and instrumental analysis only in the absence of the Smile Lite (P<.001).

CONCLUSIONS

The color similarity between visual and instrumental analysis improved with the use of a light-correcting device with or without a polarization filter. A gray background was useful only without the light-correcting device.

Color difference for shade determination with visual and instrumental methods: a systematic review and meta-analysis

BACKGROUND

Shade determination is a critical step for the fabrication of a satisfactory restoration. Visual shade selection with conventional shade guides is subjective and influenced by variables related to light, observer, and object. Shade selection devices have been introduced to provide subjective and quantitative shade values. This systematic review and meta-analysis aimed to compare the color difference for shade selection with visual and instrumental methods.

METHODS

An initial search was conducted on databases (MEDLINE via PubMed, Scopus, and Web of Science) in addition to a manual search through references of identified articles. Studies comparing the accuracy of visual and instrumental shade selection based on ΔΕ were included in data synthesis. Mean differences (MDs) and 95% confidence intervals (CIs) were calculated to estimate the effect size for global and subgroup meta-analysis using the inverse variance weighted method and random-effects model (P ˂ 0.05). Results were presented as forest plots.

RESULTS

The authors identified 1776 articles from the initial search. Seven in vivo studies were included in the qualitative analysis of which six studies were included in the meta-analysis. For the global meta-analysis, the pooled mean (95% CI) was - 1.10 (- 1.92, - 0.27). Test for overall effect showed that instrumental methods were significantly more accurate than visual methods with significantly less ΔΕ (P = 0.009). Test for subgroup difference showed that the type of instrumental shade selection method used had a significant effect on accuracy (P ˂ 0.001). Instrumental methods including spectrophotometer, digital camera, and smartphone showed significantly better accuracy compared with visual shade selection (P ˂ 0.05). The greatest mean difference was found between the smartphone and visual method with a mean (95% CI) of - 2.98 (- 3.37, - 2.59) with P ˂ 0.001 followed by digital camera and spectrophotometer. There was no significant difference in accuracy between IOS and visual shade selection (P = 1.00).

CONCLUSIONS

Instrumental shade selection with a spectrophotometer, digital camera, and smartphone showed significantly better shade matching compared with a conventional shade guide, whereas IOS did not improve the shade matching significantly compared with shade guides.

REVIEW REGISTRATION

PROSPERO CRD42022356545.

Dehydration Time Effect on Tooth Color Measurement: An In Vitro Study

OBJECTIVES

 Esthetics have become a primary influencing factor for patient satisfaction, thus dental restorations shade selection is critical, as it should closely resemble a healthy tooth. During various dental procedures, teeth are subjected to dehydration. The commonly used shade guides are being replaced with electronic color measurement devices for more precise measurements. The aim of this study was to evaluate the effect of dehydration time on tooth color measurement using a spectrophotometer.

MATERIALS AND METHODS

 Study sample is represented by 20 extracted caries-free maxillary central incisors, which were obtained from several private clinics in Riyadh, Saudi Arabia, and soaked in normal saline for 24 hours. The VITA Easyshade Advance 4.0 spectrophotometer was used to measure the color at different areas of the tooth (cervical, middle, and incisal thirds) at three time intervals (baseline, after 1 hour of dehydration, and after 2 hours of dehydration).

STATISTICAL ANALYSIS

 All color coordinates across the different areas of each tooth at the incisal, middle, and cervical thirds descriptive statistics of mean (standard deviation) values were calculated and were compared at the different time intervals at baseline, after 1 hour of dehydration, and after 2 hours of dehydration. Finally, the color change value ∆E was calculated using the formula ∆E*_ab = √ (L₂∗ - L₁∗)² + (a₂∗ - a₁∗)² + (b₂∗ - b₁∗)².

RESULTS

 The color difference ∆E showed statistically significant changes at different time intervals: at baseline, after 1 hour of dehydration, and after 2 hours of dehydration (p < 0.001). Hue had statistically significant changes between 1 hour and 2 hours of dehydration (p = 0.002). Chroma value also showed statistically significant changes (p < 0.001) in all time intervals.

CONCLUSION

 By using VITA Easyshade Advance 4.0 spectrophotometer, it was indicated that the tooth color measurements were significantly affected by dehydration time, and tooth shade appeared lighter due to changes in the refractive indices as air replaces the interprism spaces within the enamel. Tooth color measurements for shade selection should be taken as soon as possible to limit dehydration effect and ensure a more accurate shade selection for an enhanced esthetic result.

Accuracy and repeatability of different intraoral instruments on shade determination compared to visual shade selection

OBJECTIVE

To evaluate the accuracy and repeatability of intraoral instruments used for shade determination compared to visual shade selection (VSS).

MATERIALS AND METHODS

A total of 20 subjects and 10 observers, balanced by gender, participated in the study. Observers performed VSS of the upper right central incisor from each subject. Instrumental shade determination of the same teeth was performed using a spectrophotometer (Easyshade V) and intraoral scanners (CEREC Omnicam, Primescan, Trios 3 and Trios 4). Vita Classical shade nomenclature was used to record the shade designation for all instruments and VSS. The accuracy of the instruments was determined by comparing the instrument readings with the most frequent visual shade selected. The percentage of accuracy was obtained by comparing the number of agreements with the number of comparisons. The percentage of repeatability was obtained by comparing the number of repeated shades with the number of shade measurements in each group. Accuracy was compared using Cochran Q test followed by pairwise comparisons using multiple McNemar's tests with Bonferroni correction. Repeatability of the instruments was evaluated using Cronbach's alpha.

RESULTS

Omnicam showed a significant lower accuracy than the other instruments (p < 0.05). No statistical difference on repeatability was found among the different instruments (p > 0.05). It was not found any statistical differences for VSS accuracy among the observers (p = 0.437) and between genders (p = 0.867).

CONCLUSION

Instrumental repeatability (≥75%) and similar accuracy between the best performed instruments (69%-77.5%) and the observers performance (65%-90%) supports the use of high-performance instruments for dental shade determination.

CLINICAL SIGNIFICANCE

Most instruments (Easyshade V, Primescan, Trios 3, and Trios 4) showed similar accuracy performance to observers in the VSS.

The Accuracy and Reliability of Tooth Shade Selection Using Different Instrumental Techniques: An In Vitro Study

This study aimed to investigate and compare the reliability and accuracy of tooth shade selection in the model using 30 milled crowns via five methods: (1) digital single-lens reflex (DSLR) camera with twin flash (TF) and polarized filter (DSLR + TF), (2) DSLR camera with a ring flash (RF) and polarized filter (DSLR + RF), (3) smartphone camera with light corrector and polarized filter (SMART), (4) intraoral scanner (IOS), and (5) spectrophotometer (SPEC). These methods were compared with the control group or manufacturer’s shade. The CIE Lab values (L, a, and b values) were obtained from five of the methods to indicate the color of the tooth. Adobe Photoshop was used to generate CIE Lab values from the digital photographs. The reliability was calculated from the intraclass correlation based on two repetitions. The accuracy was calculated from; (a) ΔE calculated by the formula comparing each method to the control group, (b) study and control groups were analyzed by using the Kruskal–Wallis test, and (c) the relationship between study and control groups were calculated using Spearman’s correlation. The reliability of the intraclass correlation of L, a, and b values obtained from the five methods showed satisfactory correlations ranging from 0.732–0.996, 0.887–0.994, and 0.884–0.999, respectively. The ΔE from all groups had statistically significant differences when compared to the border of clinical acceptance (ΔE = 6.8). The ΔE from DSLR + TF, DSLR + RF, SMART, and SPEC were higher than clinical acceptance (ΔE > 6.8), whereas the ΔE from IOS was 5.96 and all of the L, a, and b values were not statistically significantly different from the manufacturer’s shade (p < 0.01). The ΔE of the DSLR + RF group showed the least accuracy (ΔE = 19.98), whereas the ∆E of DSLR + TF, SMART, and SPEC showed similar accuracy ∆E (ΔE = 10.90, 10.57, and 11.57, respectively). The DSLR camera combined with a ring flash system and polarized filter provided the least accuracy. The intraoral scanner provided the highest accuracy. However, tooth shade selection deserves the combination of various techniques and a professional learning curve to establish the most accurate outcome.

Visual and digital tooth shade selection methods, related effective factors and conditions, and their accuracy and precision: A literature review

OBJECTIVE

Despite developments of dental shade selection methods, shade selection is still a challenge affecting esthetic outcomes. The purpose of this review was to discuss visual and digital shade taking methods, related effective factors and conditions, and their accuracy and precision to find out the most accurate, precise shade selection method available in dentistry.

OVERVIEW

The key terms of accuracy, background, ceramic, color, colorimeter, color analysis, color science, color measurement, color measuring instrument, color matching, composite resin, dental/tooth shade guide, digital camera, esthetics, imaging, imaging application/program/ software, intraoral scanner, light source, photography, precision, shade, shade matching/ determination/prediction/reproduction/selection, shade taking device, spectrophotometer, spectrophotometry, tooth color measurement, tooth color/shade, and visual perception were used separately and jointly to detect related English-language articles published between January 1, 1985, and January 1, 2021. Electronic/non-electronic searches of Google Scholar/PubMed/Scopus/Web of Science were accomplished. Consequently, 249 articles were considered. Accordingly, the digital methods show higher accuracy and precision compared to the visual methods while requiring to be enhanced regarding accuracy to achieve ideal shade taking results.

CONCLUSIONS

Dental spectrophotometers provide the highest overall accuracy and precision among different shade selection methods while needing clinical setting to control related effective factors/conditions and technological improvement to perform optimally.

CLINICAL SIGNIFICANCE

Different factors can affect the accuracy and precision of tooth shade selection methods and devices. The understanding of these effective factors may lead to a standard shade taking protocol using accurate, precise methods and devices.

Validity and reliability of tooth color selection by smartphone photography and software applications

Aim:

This study assessed the validity and reliability of color selection by smartphone photography using two smartphone applications and Adobe Photoshop software.

Settings and Design:

In vitro comparative study.

Materials and Methods:

The validity and reliability of dental tooth shade recognition (DTSR), Chromatcher, and Adobe Photoshop were evaluated for color selection of shade tabs. The iPhone 7 camera in automatic mode was used for photography. Images were captured using Smile Lite with/without polarized filter and with camera flash. To assess the reliability, nine Vita Lumin Vacuum shade tabs were chosen and each was photographed for 10 times using Smile Lite. The reliability of DTSR, Chromatcher, and Photoshop in shade-taking was calculated. To assess their validity, 16 shade tabs of Vita Lumin Vacuum and 26 shade tabs of Vita 3D Master were photographed using the aforementioned lighting conditions. The color of photographs was calibrated and shade-taking was performed and compared with the shade suggested by SpectroShade as reference.

Statistical Analysis Used:

Data were analyzed using Two-way analysis of variance and Bonferroni post hoc test.

Results:

The reliability of Photoshop, DTSR, and Chromatcher was 98.88%, 63.3%, and 100%, respectively. The validity of Photoshop was significantly higher than other software programs (P < 0.05). Chromatcher had higher validity than DTSR (P < 0.05).

Conclusion:

Shade-taking by calibrated smartphone pictures and Adobe Photoshop has high validity and reliability.

Color interaction between resin composite layers: An overview

OBJECTIVE

Resin composite (RC) layering is increasingly popular in restorative dentistry. However, little is known regarding the color interaction between RC layers. The objective of this article is to review the current literature on color interaction between RC layers and its effect on the overall appearance of the double-layer restoration.

OVERVIEW

A literature review was conducted on theoretical and experimental in vitro studies that tested layered RC systems using different thicknesses. This article discusses specimen design, color measurement methods and devices, parameters defined as outcomes, and RC shades and systems used in the studies of double-layered RC that were reviewed here. Relevant clinical findings and gaps that still exist in the literature were also highlighted.

CONCLUSIONS

Various methods to test layered RC were found in the literature. Each study had a unique design and provided valuable information on color interaction between the enamel and dentin layers that could be applied to clinical use. For more predictable esthetic outcomes, manufacturers could provide tailored recommendations specific for their RC systems, stating the recommended thickness and shade for each layer used in the RC layering technique.

CLINICAL SIGNIFICANCE

With increased variability in RC shades and manufacturers, it is often difficult to predict the final overall color of restoration with multiple layers. Advancing research on RC layering will help clinicians deliver the best customized restorative treatment tailored to the needs and expectations of their patients. Future research along these lines can enhance the efficiency of chair time and will increase the satisfaction of both clinicians and patients.

The One-Year In Vivo Comparison of Lithium Disilicate and Zirconium Dioxide Inlays

The objective of the present study was to evaluate the one-year clinical performance of lithium disilicate (LD) and zirconium dioxide (ZrO₂) class II inlay restorations. Thirty healthy individuals who met the inclusion criteria were enrolled for the study. The patients were randomly divided into two study groups (n = 15): LD (IPS e.max press) and ZrO₂ (Dentcare Zirconia). In the ZrO₂ group, the internal surfaces of the inlays were sandblasted and silanized with Monobond N (Ivoclar, Leichsteistein, Germany). In the LD group, the internal surfaces of the inlays were etched with 5% hydrofluoric acid. The ceramic inlays were cemented with self-cure resin cement (Multilink N). Clinical examinations were performed using modified United State Public Health Codes and Criteria (USPHS) after 2 weeks, 4 weeks, 6 months and 1 year. The one-year survival rate was evaluated. In total, one failure was observed in the ZrO₂ group. The survival probability after 1 year for the ZrO₂ inlays was 93%, and for the LD inlays was 100%, which was statistically insignificant. The differences between both groups for most USPHS criteria (except for colour match) were statistically insignificant. Within the imitations of the present study, the lithium disilicate- and zirconia dioxide-based inlays exhibited comparable clinical performances. However, the colour and translucency match was superior for the lithium disilicate restorations.

In-office bleaching with low/medium vs. high concentrate hydrogen peroxide: A systematic review and meta-analysis

OBJECTIVE

To answer the following research question: "Dolow/medium hydrogen peroxide (HP) concentrations used for in-office bleaching in patients with permanent dentition have similar color change and bleaching sensitivity (BS) to high HP concentrations?"

DATA

Randomized controlled trials that compared low/medium vs. high concentrate HP were included. The risk of bias (RoB) was evaluated using the Cochrane Collaboration tool. Meta-analyses were conducted for color change (ΔE*ab, ΔSGU/SGU), risk, and intensity of BS, using the random-effects model. Heterogeneity was assessed with the Cochrane Q test, I2 statistics, and prediction interval. The GRADE assessed the certainty of the evidence.

SOURCES

Search was performed in PubMed, Cochrane Library, BBO, LILACS, Scopus, Web of Science and grey literature on 15th September 2018 (updated on 13th May 2020).

STUDY SELECTION

25 studies remained. Five were at low RoB; thirteen were at unclear RoB, and seven were at high RoB. The risk of having BS was, on average, 33 % lower (RR = 0.67; 95 % CI 0.51 to 0.86) for low/medium concentrate HP than high HP. No significant difference in color change was detected among groups, except from the subgroup low vs. high HP for the immediate color change, but this difference is not clinically relevant. The certainty of evidence for color change was low and very low, and moderate for the BS.

CONCLUSIONS

Low and medium hydrogen peroxide concentrate products for in-office bleaching have lower risk and intensity of bleaching sensitivity than the high concentrate hydrogen peroxide group, with no difference in color change efficacy.

CLINICAL SIGNIFICANCE

The use of low concentrate hydrogen peroxide products may produce the same color change efficacy with the bonus of having lower risk and intensity of bleaching sensitivity. However, the ideal concentration at which this occurs is yet unknown and deserves further investigations. No funding. PROSPERO CRD42018108266.

Accuracy and repeatability of different intraoral scanners on shade determination

OBJECTIVE

To evaluate the accuracy and repeatability of different intraoral scanners on shade determination.

MATERIALS AND METHODS

Ten different shades of Vita Mark II blocks were used. A disc-shape specimen (10 mm in diameter and 1 mm thick) per ceramic block was fabricated. Ten color measurements per specimen were performed by each instrument (Vita Easyshade V [control], 3shape Trios, Cerec Omnicam, Cerec Primescan) and recorded in Vita Classic color system. The number of correct shade match per instrument for each shade was recorded. Instrumental accuracy was compared using Cochran Q test and repeatability was analyzed using Cronbach's alpha.

RESULTS

There was a significant difference in the instrumental accuracy for shade determination (p < 0.001). There was no statistical difference between the Easyshade V (78%) and the 3Shape Trios (66%) (p > 0.05), with the latter being similar to the other scanners Primescan(63%) and Omnicam (57%) (p > 0.05). No significant difference was found (p > 0.05) when different shades were evaluated by the same instrument. Similar repeatability was found for the different devices, ranging from 44.3% for Easyshade to 51.9% for Omnicam.

CONCLUSION

The evaluated instruments showed less than expected repeatability and accuracy on measuring different dental shades. Therefore, caution should be exercised when using instrumental shade determination, which should be accompanied by experienced human visual assessment.

CLINICAL SIGNIFICANCE

The outcome of this study might help clinicians evaluate the performance of intraoral scanners as a shade matching tool.

Efficacy of 980 nm diode laser and 2940 nm Er: YAG laser in gingival depigmentation: A comparative study

BACKGROUND

Gingival hyper-pigmentation is an esthetics problem in patients with excessive gingival display. Laser ablation has been suggested recently as the most effective, pleasant, and reliable technique for gingival depigmentation compared to blade surgery.

AIM

The present study aimed to identify and compare the effectiveness of two types of lasers, Er:YAG laser-2940 nm and Diode laser-980 nm, in gingival depigmentation in the maxilla and mandible.

PATIENTS/METHODS

20 participants, 16 males, and 4 females, whose ages ranged between 18 and 35 years, were recruited using simplified random sampling. Oral pigmentation was measured at pre- and two postoperative follow-ups, 1 month, and 6 months, according to the oral pigmentation index. Furthermore, the study assessed postoperative intensity of pain using the Visual Analogue Scale, bleeding and healing process in both groups.

RESULTS

There was a significant decrease in the oral pigmentation index scores, 1 month (0.90 ± 0.64) and 6 months (1.55 ± 0.60) after the operation (P < .001). No significant differences were detected between the two study groups regarding the mean ranking on the oral pigmentation index pre-operatively (P = .547), 1 month after the operation (P = .154), and 6 months after the operation (P = .831).

CONCLUSIONS

The Er:YAG laser and Diode laser both significantly reduced gingival pigmentation with no significant differences between the effectiveness of the two types of laser in treating gingival hyper-pigmentation.

Impact of the ambient light illuminance conditions on the shade matching capabilities of an intraoral scanner

PURPOSE

To compare the shade matching capabilities between an intraoral scanner (IOS) and a spectrophotometer under different ambient light illuminance conditions.

MATERIAL AND METHODS

The shade of three teeth of a patient was obtained using an IOS (IOS group) (TRIOS 3; 3Shape) and a spectrophotometer (DS group) (EasyShade V; Vita Zahnfabrik) at 4 ambient illuminances: 10000-, 1000-, 500-, and 0-lx. Ten shade measurements were documented using Vita Classical and 3D-Master guides per tooth at each lighting condition. Data was analyzed using the Kruskal-Wallis and Mann Whitney U tests (α = .05).

RESULTS

Significant shade discrepancies were obtained between the groups in different lighting conditions (P < .05). The IOS group presented significant shade discrepancies in different lighting conditions when evaluated using either shade guide, with lower variation under the 0-lx condition. However, the DS group did not present significant shade discrepancies among the different lighting conditions with either shade guide, except for the maxillary lateral incisor measured under 10 000-lx condition using the 3D-Master guide.

CONCLUSIONS

Lighting conditions influenced the shade matching competency of an IOS. The IOS tested obtained high variation in the different lighting conditions evaluated and provided a lower shade value than the spectrophotometer. The spectrophotometer revealed high consistency amongst the various lighting conditions evaluated.

CLINICAL IMPLICATIONS

Ambient light illuminance conditions can impact the shade matching capabilities of IOSs. The results of this investigation suggest the use of a supplementary instrumental method for assessment of tooth shade.

Evaluation of reservoirs in bleaching trays for at-home bleaching: a split-mouth single-blind randomized controlled equivalence trial

Objectives

This randomized, split-mouth, single-blinded trial assessed whether the use of reservoirs in at-home bleaching trays is equivalent to non-reservoir trays. Our choice of an equivalence trial was based on the expectation that a non-reservoir tray is sufficient to produce a color change. Secondary outcomes such as tooth sensitivity (TS) and gingival irritation (GI) were also assessed.

Methodology

Forty-six patients were selected with canines shade A2 or darker. In half of the patient’s arch, bleaching trays were made with reservoirs and the other half, without reservoirs. At-home bleaching was performed with carbamide peroxide (CP) 10% (3 h daily; 21 days). Color change was evaluated with a digital spectrophotometer (ΔE, ΔE00, and Whiteness Index) and shade guide units (ΔSGU) at baseline, during and one-month post-bleaching. TS and GI were assessed with a numeric scale (NRS) and a visual analog scale (VAS).

Results

After one month, the equivalence of reservoir and non-reservoir groups were observed in all color instruments (p>0.05). Fifteen and sixteen patients presented pain (absolute risk: 33% and 35%, 95%, confidence interval (CI) 21-46% and 23-49%) in the reservoir and non-reservoir side, respectively. The odds ratio for pain was 0.8 (95%CI 0.2-3.0) and the p-value was non-significant (p=1.0). TS intensity was similar between both groups in any of the pain scales (p>0.05). No difference in the GI was observed (p>0.05).

Conclusions

The protocol with reservoirs is equivalent in color change to the non-reservoir, although no superiority of the latter was observed in terms of reduced TS and GI with at-home 10% carbamide peroxide bleaching.

Clinical Relevance

The presence of reservoirs in a bleaching tray did not improve color change or affect tooth sensitivity and gingival irritation.

Dentin Staining Caused by Nano-silver Fluoride: A Comparative Study

CLINICAL RELEVANCE

The new formulations of nano-silver fluoride caused less dentin staining than the already available commercial agents 35% silver fluoride and silver diamine fluoride at 30% and 38%.

SUMMARY

The objective of this study was to evaluate the dentin staining potential of nano-silver fluoride (NSF 600 and 1500 ppm) compared with the following commercially available cariostatic agents: Advantage Arrest (Elevate Oral Care, West Palm Beach, FL, USA), Riva Star (SDI, Victoria, Australia), and Cariestop (Biodinâmica, Paraná, Brazil). Seventy-five extracted human molars were sectioned at the cementoenamel junction, and the occlusal enamel was removed for exposure of coronary dentin. The samples were divided among the five agents tested (n=15). The dentin staining (ΔE/ΔL) was analyzed with a digital spectrophotometer (VITA Easyshade, VITA Zahnfabrik, Bad Säckingen, Germany) at three different time points (before application, after two weeks, and after four weeks). Photographic images were also performed. The Kruskal-Wallis and Mann-Whitney tests compared the mean ΔE and ΔL values between groups. The NSF 600 and 1500 ppm resulted in the smallest color change (ΔE=1.02 and 1.53) and dentin staining after four weeks (ΔL=-0.76 and -1.2). The new formulations differed significantly from the commercial cariostatic agents (p<0.001). NSF might be an alternative to silver diamine fluoride since it does not compromise esthetics.

Tooth shade analysis and selection in prosthodontics: A systematic review and meta-analysis

Aim:

To evaluate the methods of the dental shade selection and provide a summary of different factors affecting the shade selection.

Design and Setting:

The systematic review and meta-analysis.

Materials and Methods:

The electronic search of the peer-review articles between 2002 and 2018 was carried out the by using the PRISMA guidelines. A total twenty-one studies related to the visual shade methods, instrumental shade methods, and the factors affecting the shade selections was evaluated. The search strategy was based on the PICOS framework.

Statistical Analysis:

There was statistically significant heterogeneity (Q = 1038.1518, df = 20, and P < 0.0001). The statistics of fixed-effect model reported an MD of − 0.0970 (95% CI = −0.1391, −0.0549). The random-effect model reported an MD of − 0.0862 (95% CI = −0.5866, 0.4142).

Result:

The review evaluated the 21 studies of tooth colour science that met with the inclusion criteria and search criteria. The meta-analysis of the 21 combined studies reported acceptable homogeneity (i² = 98%) which indicates a statistically significant difference between the treatment and control groups.

Conclusion:

The VES spectrophotometer reported the highest accuracy, reliability, and repeatability in shade selection followed by photo colorimetric method. The Vita 3D master shows more consistent results in repetitive shade selection. Knowledge and training of the shade selection protocol are necessary for proper shade matching

Repeatability of the human eye compared to an intraoral scanner in dental shade matching

Objective

The purpose of this investigation was to compare the repeatability of an intraoral scanner (3Shape TRIOS) with the traditional visual method for dental shade matching in patients and to assess the influence of ambient lighting and the observer's sex and experience on visual shade matching. An additional aim was to determine the color dimension for which repeatability is greater with both the visual method and intraoral scanner.

Methods

Thirty observers (15 men and 15 women), grouped by professional experience, selected the shade of the right maxillary central incisor in 10 patients on three different occasions under different ambient lighting conditions (twice under studio clinic lighting and once under natural light). The same procedure was repeated using an intraoral scanner. All shades were selected based on the VITA Toothguide 3D-MASTER. The repeatability of each observer and the intraoral scanner were recorded for each color dimension (hue, chroma, and value).

Results

The TRIOS intraoral scanner obtained a mean repeatability of 86.66% in dental shade matching compared to 75.22% achieved by the visual method. Ambient lighting had a direct effect on the repeatability of the shade selection for the visual method, whereas the observer's sex and clinical experience did not. For the visual method, the repeatability in dental shade matching depended on the dimension studied, with the best results in value, followed by hue and chroma; however, such dependence was not detected for the intraoral scanner.

Conclusions

The TRIOS intraoral scanner ensured better repeatability than the visual method in dental shade matching.

Does the Use of Reservoirs Have Any Impact on the Efficacy of At-Home Bleaching? A Systematic Review

Abstract To answer the following focused question through a systematic review: “Are the risk and intensity of tooth sensitivity (TS) and bleaching efficacy different between adult patients who undergo at-home bleaching using trays with reservoirs and those who use trays without reservoirs?”. A comprehensive search was performed in the MEDLINE via PubMed, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature database, Brazilian Library in Dentistry, Cochrane Library, and grey literature without restrictions. Abstracts from conferences; unpublished and ongoing trial registries, dissertations and theses (ProQuest Dissertations and Periódicos Capes Theses databases) were searched. Only randomized clinical trials (RCTs) were included. We used the Risk of Bias tool (RoB) from the Cochrane Collaboration for quality assessment. After the removal of duplicates, title and abstract screening and full-text examination, nine RCTs remained for qualitative analyses. The great majority of the studies did not report the method of randomization, allocation concealment, and examiner blinding during color assessment. From the nine studies, eight were at unclear risk of bias. In regard to color change, four studies reported no change and two reported improved color change with reservoirs. Only four studies recorded tooth sensitivity and they reported no significant differences. Only one study reported greater gingival irritation with reservoirs. Lack of data reporting prevented us from running a meta-analysis. Further well-designed RCT should be conducted to answer this research question. So far there is not evidence to support that reservoirs in bleaching trays improve color change. PROSPERO - CRD42016037628

Evaluation of small-group education on the shade determination ability of preclinical dental students-A controlled clinical trial

OBJECTIVES

To evaluate the effect of small-group education including practical training on dental students' shade determination performance compared with a control group.

METHODS

Sixty-three non-colour-blind preclinical students were asked to participate and belonged to an intervention (n = 31) and a control (n = 32) group, respectively. All students received a lecture on dental shade determination. The members of the intervention group were educated and practically trained in small groups in addition. Ten volunteers, each with unrestored upper right middle and lateral incisors, were recruited. The students of both the intervention and control groups were then asked to determine the colour of the volunteers' test teeth using the 3D-Master shade guide (Vita Zahnfabrik, Bad Säckingen, Germany) under artificial daylight illumination. For analytical purposes, the CIE L*a*b* coordinates were obtained using a spectrophotometer. Colour differences, ΔE, between all shade tabs selected by the students and the natural teeth were calculated. ΔE observed in the intervention and control groups were compared using t tests. In addition, a multi-level regression model was adjusted for age and gender.

RESULTS

Mean (SD) ΔE between the shade tabs selected by the students and the natural teeth in the intervention and control groups were 3.8 (2.1) and 4.3 (2.3), respectively (P < .001). The effect of group membership was reproduced in multivariate analysis whereas age and gender did not reach statistical significance.

CONCLUSIONS

With more intensive education and practical training the ability to perform clinical shade determinations improved for students without previous clinical experience. The results obtained support the idea of implementing thematic small-group education in the dental curriculum.

Comparison of efficacy of tray-delivered carbamide and hydrogen peroxide for at-home bleaching: a systematic review and meta-analysis

OBJECTIVES

The aim of the study was to compare the color change produced by tray-delivered carbamide peroxide [CP] versus hydrogen peroxide products [HP] for at-home bleaching through a systematic review and meta-analysis.

MATERIALS AND METHODS

MEDLINE via PubMeb, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature database (LILACS), Brazilian Library in Dentistry (BBO), and Cochrane Library and Grey literature were searched without restrictions. The abstracts of the International Association for Dental Research (IADR) and unpublished and ongoing trial registries were also searched. Dissertations and theses were explored using the ProQuest Dissertations and Periodicos Capes Theses databases. We included randomized clinical trials that compared tray-delivered CP versus HP for at-home dental bleaching. The color change in shade guide units (SGU) and ΔE were the primary outcomes, and tooth sensitivity and gingival irritation were the secondary outcomes. The risk of bias tool of the Cochrane Collaboration was used for quality assessment.

DATA

After duplicate removal, 1379 articles were identified. However, only eight studies were considered to be at "low" risk of bias in the key domains of the risk bias tool and they were included in the analysis. For ΔE, the standardized mean difference was -0.45 (95 % CI -0.69 to -0.21), which favored tray-delivered CP products (p < 0.001). The color change in ΔSGU (p = 0.70), tooth sensitivity (p = 0.83), and gingival irritation (p = 0.62) were not significantly different between groups.

CONCLUSIONS

Tray-delivered CP gels showed a slightly better whitening efficacy than HP-based products in terms of ΔE, but they were similar in terms of ΔSGU. Both whitening systems demonstrated equal level of gingival irritation and tooth sensitivity.

CLINICAL SIGNIFICANCE

Tray-delivered CP gels have a slightly better whitening efficacy than HP-based products in terms of ΔE. This should be interpreted with caution as the data of ΔSGU did not show statistical difference between the products.

The effect of powder A2/powder A3 mixing ratio on color and translucency parameters of dental porcelain

PURPOSE

The purpose of this study is to mix dental ceramic powder in varying ratios and evaluate the effect of the mixing ratio on color and translucency.

MATERIALS AND METHODS

The ceramic powder of shade A3 of the same product was mixed with the shade A2 of three products: IPS e.max Ceram (Ivoclar Vivadent, Schaan, Liechtenstein), Vintage Halo (SHOFU Inc., Kyoto, Japan), and Ceramco 3 (Ceramco-Dentsply, Burlington, NJ, USA) in the following fixed ratios (0 wt%, 25 wt%, 50 wt%, 75 wt%, and 100 wt%) and then fired. A total of 150 specimen of ceramic fired were manufactured in a regular size (W: 8.5 mm, L: 10.5 mm, and H: 1.5 mm). For color and translucency, L*, a*, and b* were measured and Two-way analysis of variance (ANOVA) and One-way analysis of variance (ANOVA) were used for data analysis (α=0.05).

RESULTS

The higher the mixing ratio was, L*, a*, and b* of IPS e.max Ceram were all increased, and L* of Vintage Halo was reduced and a* and b* were increased. L* and a* of Ceramco3 were reduced and b* of Ceramco3 was increased. Color difference (ΔE*ab) was increased in all three products as the mixing ratio got higher. Increased mixing ratios resulted in decreased translucency parameter (TP) values for IPS e.max Ceram but increased TP values for Vintage Halo and Ceramco3.

CONCLUSION

In this limited study, CIE L*, a*, and b* were influenced by the mixing ratio of the A3 powders and porcelain powder mixtures represented a various color and translucency.