Crown Shade Selection Errors: What the Evidence Says

Introduction

A crown that fits perfectly but does not match the adjacent teeth is still a failed restoration from the patient's point of view. Shade errors cost the dental laboratory a remake, the dentist additional chair time and the patient another appointment. In a retrospective audit of 40,344 indirect restorations fabricated in seven dental laboratories in Riyadh, the authors noted that remakes increase chairside time, laboratory costs and patient dissatisfaction [PMID 41680354]. A 2022 meta-analysis notes that colour matching is considered a subjective procedure and describes accurate shade choice as often the most challenging stage of recreating the natural appearance of teeth [PMID 35057185].

This article reviews the published evidence on crown shade selection errors for dental laboratories and the dentists who send work to them: how often shade contributes to remakes, where errors arise between the chair and the bench, which shade selection methods perform best, and what a laboratory can do to reduce shade-related returns.

How often do shade problems lead to remakes?

Shade is one of several causes of remakes; in the largest audit identified, fit-related reasons were reported more often than shade.

Single-unit crowns in US practices. In the National Dental Practice-Based Research Network, 205 dentists evaluated 3750 single-unit crowns. The remake rate was 3.8%, and the most common reasons for rejection were proximal misfit, marginal errors and esthetic failures [PMID 30412320].
A multicentre laboratory audit. Among 40,344 restorations from seven laboratories there were 2,612 remakes; remake prevalence was 7.5% for veneers, 7.1% for onlays and 6.9% for crowns. The leading reasons were margin-fit discrepancy (29.5%), proximal-fit issues (23.2%) and improper fit (22.7%), and shade mismatch was more frequent with lithium disilicate restorations. The authors identified clearer laboratory prescriptions as one addressable target [PMID 41680354].

In our reading, these data indicate that shade-related remakes are a recurring and partly preventable cost, but that a laboratory's quality programme should address shade alongside fit rather than in isolation.

Where shade errors arise

1. Communication between the clinic and the laboratory

The laboratory can only reproduce the shade information it receives. Surveys of technicians repeatedly describe incomplete work authorisations. In a US survey of 199 laboratories (114 responses, 57%), respondents reported a lack of communication through work authorisation forms regarding choice of metal alloy, type of porcelain and margin and pontic design [PMID 16650014]. A survey of 66 laboratories in Riyadh found a lack of communication about marginal design, pontic design, staining diagrams and the type of porcelain and glaze, with a greater deficit in government laboratories [PMID 28725128].

The format of the prescription appears to matter. In a quasi-experimental study in Jordan comparing 300 paper-based prescriptions with 300 prescriptions submitted through an information technology system, the digital system was associated with more complete recording of essential information, faster completion and delivery, less need for re-communication, and less need for modification or redo due to improper shade or inappropriate tooth charting (P < 0.05) [PMID 39507287].

2. The observer

Visual shade matching is limited by human perception, even among trained professionals.

Accuracy is low and chroma is hardest. When 24 operators assessed veneers of a known shade, shade assessment accuracy was only 5.5% under natural light and 9.7% under a colour-corrected light. Most operators identified value and hue correctly, but chroma was mostly identified incorrectly; technicians recorded the most accurate assessments [PMID 33934579].
Agreement with instruments varies by colour dimension. In 1361 maxillary central incisors, agreement between visual selection and a spectrophotometer was greatest for lightness (kappa 0.6587), followed by hue (kappa 0.4337) and chroma (kappa 0.3578) [PMID 24140995].
Inconsistency is common. In a study of 18 dental technicians and 40 dentists, many participants were inconsistent in their approach to shade matching, and performance on the Farnsworth-Munsell 100 Hue test did not predict shade matching performance [PMID 22158197].
Colour vision deficiency. Among 150 dental students, interns, general dentists and specialists in Saudi Arabia, 6.0% had red-green colour vision deficiency and 15.3% had borderline findings; shade-matching accuracy was lowest in those with red-green deficiency [PMID 42819069].

Evidence on the effect of the observer's sex and experience is mixed. A systematic review of 37 studies found that 25 reported no significant difference between sexes, and concluded that sex is unlikely to be a critical factor [PMID 34843155]. In a multicentre study of 614 participants, the level of experience was not a significant factor in shade matching [PMID 19520478].

3. Conditions at the time of shade selection

Dehydration. In 32 participants, tooth colour changed beyond the perceptibility threshold within the first minute of isolation; after the first minute, 87% of teeth exceeded the perceptibility threshold and 72% exceeded the acceptability threshold, and teeth had not rehydrated within 15 minutes. The authors recommended that shade be selected at the beginning of the procedure, before teeth dehydrate [PMID 30801926].
Lighting. In a study of 100 subjects comparing daylight, a dental operating light and a colour-corrected light, the light source significantly affected visual shade selection, and the authors concluded that visual matching produces the best results under a colour-matching light [PMID 32068979]. In a clinical study of 30 volunteers, a light-correcting device improved the similarity between visual and instrumental analysis, and a grey background helped only when the light-correcting device was not used [PMID 38228448].

4. The material and the shade system

Shade errors are not purely clinical. In a 2026 study of CAD-CAM lithium disilicate crowns in VITA Classical shades A3, B3, C3 and D3, mean colour differences exceeded the ΔE00 acceptability threshold of 1.8 for A3, B3 and C3 crowns relative to their corresponding shade tabs, with the greatest difference in C3; the authors reported an inconsistency between measured colour values and the nominal shade [PMID 41996648]. This is consistent with the Riyadh audit, in which shade mismatch was more frequently associated with lithium disilicate [PMID 41680354].

How much colour difference is acceptable?

A multicentre study involving 175 observers, including dentists and dental technicians, determined a 50:50% perceptibility threshold of ΔEab 1.2 and an acceptability threshold of ΔEab 2.7 for dental ceramics; the corresponding CIEDE2000 values were 0.8 and 1.8 [PMID 25886208]. A later review describes these thresholds as a quality control tool and notes that clinical and research findings cannot be fully interpreted without them [PMID 30891913].

In our reading, a laboratory that measures finished restorations instrumentally can use these thresholds as an objective reference when discussing a disputed shade with a clinic, rather than relying on subjective impressions alone.

Which shade selection method performs best?

Visual versus instrumental. A systematic review of 26 studies concluded that spectrophotometers may provide the most precise and accurate shade matching, but that higher-quality studies are still needed [PMID 23034418]. A systematic review and meta-analysis of 21 studies from India concluded that knowledge and training in a shade selection protocol are necessary for proper shade matching [PMID 32655217].
Digital photography. A 2022 meta-analysis of 13 studies found that colour difference was greater when shade was matched conventionally than with computerised methods (p = 0.007). In subgroup analysis only digital photographs reduced colour difference (p < 0.0001), whereas the spectrophotometer showed no advantage over visual shade tabs (p = 0.57); incorrect shade matching was nonetheless higher with conventional shade tabs (p < 0.001) [PMID 35057185].
Clinical crown outcomes. In 45 patients receiving lithium disilicate crowns, the mean colour difference between the cemented crown and the adjacent tooth was 5.32 with visual shade selection, compared with 2.75 with a digital camera and cross-polarising filter and 2.34 with a smartphone and light-correcting device; a grey reference card helped standardise white balance [PMID 33741142]. In an earlier study of 36 patients who each received two metal ceramic crowns, crowns matched with a spectrophotometer had significantly lower colour differences, and conventionally matched crowns were more likely to be rejected (odds ratio 12.5) [PMID 18456047].
Intraoral scanners. A systematic review of 17 studies concluded that intraoral scanners show acceptable precision but unacceptable accuracy for shade matching [PMID 36347647]. A 2025 meta-analysis reported trueness between 0.28 and 0.38 and repeatability between 0.81 and 0.85, and stated that shade determination with intraoral scanners is not recommended [PMID 39248580].

Can shade matching be taught?

Training appears to help. In 174 dental students, shade matching scores improved significantly after colour education and training, from a mean of 7.06 to 8.43, while the control group showed no significant improvement [PMID 27061853]. The meta-analysis from India similarly concluded that knowledge and training of a shade selection protocol are necessary [PMID 32655217].

Practical steps for laboratories and clinics

The following steps are our interpretation of the evidence above, not a protocol tested as a whole in any single study.

Standardise the prescription. Agree a shade section that records the shade system used, the shade by region, characterisation and translucency notes and, where relevant, the preparation (stump) shade [PMID 22158197]; structured digital prescriptions were associated with fewer shade-related redos [PMID 39507287][PMID 28725128].
Ask for calibrated photographs. Request photographs with the selected shade tab in view and a grey reference card; cross-polarised or light-corrected images were associated with smaller crown colour differences than visual selection alone [PMID 33741142][PMID 30093117].
Encourage shade selection before isolation. Tooth colour changes perceptibly within the first minute of dehydration [PMID 30801926].
Specify the light. A colour-corrected or light-correcting source improves visual matching [PMID 32068979][PMID 38228448].
Use instruments where available, but not the scanner alone. Spectrophotometric data can support visual selection [PMID 23034418][PMID 18456047], whereas current reviews do not support intraoral scanner shade as the sole reference [PMID 36347647][PMID 39248580].
Check material-specific shade behaviour. Verify how the chosen ceramic and shade reproduce the target tab, particularly for lithium disilicate [PMID 41996648][PMID 41680354].
Invest in training and screening. Shade training improves performance [PMID 27061853], and colour vision screening may identify staff who would benefit from instrument-assisted matching [PMID 42819069].
Audit remakes by reason. Recording shade-related returns separately from fit-related returns allows a laboratory to target its improvement work [PMID 41680354][PMID 30412320].

D4dent's lab order workflow keeps the requested work, tooth number, shade, scans and written instructions together on the case, and ties case communication to that case, so that a question about a shade is answered in context rather than lost in a message thread. Dentists can see how orders are sent and tracked on the lab orders page for dentists, and laboratories can learn how the workflow supports intake, production, quality check and dispatch on the D4dent for labs page. D4dent connects patients, doctors, clinics, laboratories, dealers and X-ray centres in one ecosystem.

Frequently asked questions

How common are crown remakes caused by shade problems?

Shade is one of several reasons for remakes. In a US practice-based study of 3750 single-unit crowns, the remake rate was 3.8%, and the most common reasons for rejection were proximal misfit, marginal errors and esthetic failures. In an audit of 40,344 indirect restorations from seven laboratories in Riyadh, fit-related problems led the list, and shade mismatch was more frequent with lithium disilicate than with other materials.

Is a spectrophotometer more accurate than a shade guide?

Systematic reviews generally favour instrumental methods. A 2012 review concluded that spectrophotometers may provide the most precise and accurate shade matching, while noting that high-quality studies were still needed. A 2022 meta-analysis found fewer colour differences and less incorrect shade matching with digital photography and spectrophotometric measurement than with conventional shade tabs, although in its subgroup analysis the spectrophotometer showed no advantage over visual tabs for colour difference.

Can an intraoral scanner be used to select crown shade?

Current reviews advise caution. A 2024 systematic review concluded that intraoral scanners show acceptable precision but unacceptable accuracy for shade matching, and a 2025 meta-analysis found low trueness compared with spectrophotometers and stated that shade determination with intraoral scanners is not recommended.

Limitations to keep in mind

Much of the evidence on shade matching comes from in vitro studies, studies of dental students and single-centre clinical series, and the systematic reviews cited here report heterogeneity and call for higher-quality studies [PMID 23034418][PMID 32655217][PMID 34843155]. The two remake audits were conducted in the United States and Saudi Arabia [PMID 30412320][PMID 41680354], and the communication surveys reflect technicians' perspectives in those settings [PMID 16650014][PMID 28725128]; results may differ in Indian laboratories. The lithium disilicate shade study was published online ahead of print and examined a small sample [PMID 41996648]. Figures here are taken from published abstracts; readers should consult the full texts before applying specific values.

Conclusion

Crown shade selection errors arise from several sources: incomplete communication between clinic and laboratory [PMID 16650014][PMID 28725128], the limits of visual perception [PMID 33934579][PMID 24140995], dehydration and lighting at the time of selection [PMID 30801926][PMID 32068979], and the behaviour of the restorative material itself [PMID 41996648]. Instrumental and calibrated photographic methods reduce colour differences compared with visual selection alone [PMID 35057185][PMID 33741142], whereas intraoral scanner shade is not yet reliable [PMID 39248580]. In our reading, the most effective safeguard is a structured, complete shade record that travels with every case, supported by calibrated photographs, agreed lighting conditions and a remake audit that separates shade from fit.

More in this series

Receive structured lab orders with shade details, files and instructions attached to each case. Create your D4dent lab account.

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Crown Shade Selection Errors: Causes, Evidence and Prevention for Dental Laboratories