Dental caries is a chronic, multifactorial disease influenced by biological, behavioural, and environmental factors (1). It results from an imbalance between demineralization and remineralization processes mediated by biofilm activity (2). Accurate detection and proper management of carious lesions are essential to prevent disease progression, preserve tooth structure, and maintain pulp vitality (3).

Minimally invasive dentistry has gained prominence in recent years, promoting conservative strategies that prioritize tissue preservation and long-term tooth survival (4). In this context, visual-tactile inspection remains the most widely used diagnostic method. Systems such as the International Caries Detection and Assessment System (ICDAS) provide a standardized and reproducible approach to assess lesion activity and depth (5). Despite its reliability, the accuracy of visual inspection can be affected by clinical conditions and examiner experience (6).

To enhance diagnostic precision, adjunctive technologies have been developed. Fluorescence-based devices, such as DIAGNOdent and QLF, detect variations in fluorescence that correspond to demineralized tooth structure or bacterial byproducts (7). These tools have shown promise, particularly in early lesion detection, but their sensitivity and specificity vary across clinical studies (8, 9).

In cases of deep carious lesions, accurate diagnosis is particularly important, as it determines the choice of appropriate minimally invasive approaches, such as selective or stepwise caries removal, which aim to preserve pulp vitality and avoid unnecessary tissue removal. These techniques offer a conservative alternative to non-selective caries removal, which increases the risk of pulpal exposure and irreversible damage (10–14).

Previous studies have shown that selective carious tissue removal offers several advantages, including reduced risk of pulp exposure, preservation of dental and pulp tissues, and greater restoration longevity (15–17). These benefits have positioned it as one of the most recommended operative procedures in current conservative dentistry. Clinically, caries evaluation often relies on the colour and hardness of dentin. However, this method is subjective and has low reproducibility (18, 19). To improve accuracy, caries detector dyes were introduced. These dyes aim to highlight infected dentin while preserving healthy tissue (5, 20).

In 1972, a technique using a basic fuchsin red stain was suggested (and subsequently developed) to aid in the differentiation of the two layers of carious dentin (5, 6). Because of potential carcinogenicity, the basic fuchsin stain was subsequently replaced by another dye, acid red solution (7). Since then, various protein dyes have been marketed as caries detection agents (21). Caries detector dyes typically contain 1% acid red in propylene glycol and help clinicians distinguish demineralized dentin from sound tissue during excavation (22). Nevertheless, studies have reported that these dyes can overstain and lead to the unnecessary removal of sound dentin (5, 18, 23). Conversely, other investigations suggest that these dyes can aid detection, and their absence might result in undiagnosed carious tissue (19, 24–27).

In addition to chemical agents, fluorescence-based devices have been introduced. The DIAGNOdent (KaVo Dental, Biberach, Germany) uses laser fluorescence (wavelength 655 nm) to detect caries by measuring fluorescence emitted by bacterial porphyrins (28, 29). This device quantifies lesion severity numerically, offering an objective diagnostic tool (30–33).

Additionally, the Fluorescence-Assisted Caries Excavation (FACE) system (Selbekk, Oslo, Norway) enables clinicians to identify infected dentin by directly observing red-orange fluorescence, avoiding the use of dyes (34, 35). The DIAGNOdent Cam, functioning similarly to Quantitative Light-induced Fluorescence (QLF), also relies on fluorescence emissions to detect early demineralization, highlighting a diagnostic overlap that warrants further comparative studies.

To improve the sensitivity and reliability of caries detection methods, it is suggested to correlate visual and tactile criteria with microbial activity in dentin. This approach could provide a more accurate and reproducible method for both quantitative and qualitative assessment (36–38).

Therefore, this scoping review aims to evaluate diagnostic methods that support effective selective caries removal. Specifically, it compares the clinical performance of caries detector dyes and laser fluorescence devices in terms of diagnostic accuracy and support for minimally invasive approaches, such as stepwise and selective removal techniques. The review also explores their advantages regarding dental tissue preservation, pulp vitality maintenance, and the long-term success of restorative treatments.

The initial database search yielded a total of 124 records (PubMed/MEDLINE: 82; Web of Science: 42). After removal of 15 duplicates, 109 titles and abstracts were screened for eligibility. Following the screening process, 89 records were excluded based on title and abstract review for reasons such as irrelevant outcomes, study design not meeting inclusion criteria, or evaluation of non-targeted diagnostic methods.

A total of 20 full-text articles were assessed for eligibility. Of these, 16 studies were excluded for the following reasons: non-comparative design (n = 9), use of different diagnostic tools unrelated to caries detector dyes or laser fluorescence (n = 5), and studies involving primary teeth (n = 2). Ultimately, 4 studies were included in the final qualitative analysis.

The study selection process is illustrated in Figure 1.

Study designs: The selected studies (39–42) conducted between 2015 and 2024. These studies are shown in Table 1. Additionally, there was a lack of homogeneity in conventional and minimally invasive methods, requiring the combination of similar procedures with variations in their protocols.

Given the small number of studies directly comparing caries detector dyes and laser fluorescence methods, a descriptive comparison of the diagnostic values was performed. This allowed for a clearer interpretation of the diagnostic effectiveness of both methods, while respecting the methodological framework of a scoping review.

The findings in Figure 2 highlight key differences in caries detection methods. Peskersoy et al. (39) and Koç Vural et al. (40) showed that fluorescence-assisted excavation (FACE) significantly reduces residual caries compared to conventional methods. Sadasiva et al. (41) found that combining caries detector dyes with laser fluorescence enhances diagnostic accuracy and minimizes unnecessary dentin removal. Abba et al. (42) further confirmed that DIAGNOdent achieves the highest sensitivity and specificity, making it a valuable tool for selective caries removal. Similarly, Koç Vural et al. (40) reinforced this perspective by comparing different detection techniques and their impact on clinical decision-making. Their study assessed the diagnostic accuracy of visual, radiographic, and staining methods in determining the extent of dentin removal. The authors concluded that fluorescence-assisted excavation significantly enhances the identification of carious dentin while preserving as much healthy tissue as possible. On the other hand, Kanar et al. (2024) introduced a technological dimension with the use of laser fluorescence (LF) in evaluating caries removal techniques. Their study compared the effectiveness of DIAGNOdent and FACE with conventional methods, finding that fluorescence-based systems offer superior sensitivity and specificity. However, the authors noted that factors such as extrinsic pigmentation, tooth hydration, and detection threshold variability can influence their performance.

This scoping review identified that laser fluorescence-based diagnostic methods demonstrate higher sensitivity, specificity, and overall diagnostic accuracy compared to caries detector dyes in the context of selective caries removal. Both diagnostic approaches contribute to the clinical objective of preserving dentin and maintaining pulp vitality, aligning with the principles of minimally invasive dentistry. However, the available evidence remains limited, and further high-quality research is necessary to substantiate these findings and standardize clinical protocols. The primary aim of this review was to determine the most appropriate intraoperative diagnostic method to support selective caries removal by comparing the effectiveness of caries detector dyes and laser fluorescence systems in accurately identifying carious tissue, with a specific focus on tissue preservation, pulp vitality, and long-term restorative success.

A detailed comparative overview of the diagnostic performance, including sensitivity and specificity values across different studies and methods, is presented in Table 3. This table highlights the variability among techniques and supports the need for standardized protocols. Laser fluorescence systems demonstrate superior sensitivity, allowing for more reliable detection of residual infected dentin. This reduces the risk of undiagnosed carious tissue and helps ensure long-term restoration success. Similarly, the higher specificity of fluorescence-based methods minimizes the unnecessary removal of healthy, remineralizable dentin, reinforcing the goal of preserving pulp vitality and supporting the fundamental principles of selective caries removal. In contrast, the lower specificity associated with caries detector dyes may result in over-excavation and inadvertent pulp exposure, increasing the risk of operative complications and negatively impacting the long-term success of restorations. These differences in diagnostic performance have significant clinical implications, emphasizing the potential role of laser fluorescence systems as adjunctive tools to inform clinical decision-making in minimally invasive caries management. Fluorescence devices have demonstrated more consistent diagnostic performance across the analyzed studies, which may translate into greater clinical reliability. However, this hypothesis requires further validation through studies conducted in real-world clinical settings.

These findings underscore the clinical importance of selecting appropriate intraoperative diagnostic methods during selective caries removal. The greater diagnostic accuracy achieved with laser fluorescence systems—characterized by higher sensitivity and specificity—enables more reliable differentiation between infected and remineralizable dentin. This contributes to minimizing the risk of residual carious tissue and avoiding unnecessary dentin removal, both of which are critical to maintaining pulp vitality, especially in deep lesion management. Although current clinical outcome data are limited, existing evidence suggests that fluorescence-guided selective caries removal is associated with lower rates of pulp exposure and improved restorative prognosis compared to approaches relying solely on caries detector dyes. The integration of adjunctive diagnostic technologies within minimally invasive protocols may also support the standardization of clinical procedures, enhance pulp preservation, and reduce operative complications. Nonetheless, practical considerations such as the cost of devices, clinical accessibility, and the learning curve for clinicians must be addressed to facilitate the widespread adoption of these technologies in routine practice.

These practical barriers must be considered when evaluating the real-world applicability of these technologies. Although devices like DIAGNOdent and FACE offer high diagnostic accuracy and intraoperative utility, their broader clinical adoption is constrained by factors such as cost, the need for regular calibration, and operator training. DIAGNOdent is sensitive to external variables such as hydration or surface staining, which may affect its consistency. FACE, meanwhile, provides direct visual assessment of infected tissue but remains less accessible due to higher costs and limited availability. In contrast, caries detector dyes offer a low-cost, easy-to-use alternative, though their lower specificity can lead to overtreatment, particularly in the absence of magnification or standardized interpretation criteria. Therefore, selecting a diagnostic system should account not only for clinical efficacy but also for feasibility based on available resources, supporting a balanced integration into daily practice.

Despite the promising diagnostic performance of fluorescence-based methods, several limitations in the current evidence must be acknowledged. Studies such as Kanar et al. (2024) provide valuable medium-term data on restoration longevity and success but often face challenges related to patient attrition and the inability to control for confounding variables such as oral hygiene practices. Conversely, shorter-term studies (e.g., 40, 41) offer precise diagnostic performance data but do not assess the long-term clinical implications of these diagnostic methods. Furthermore, methodological heterogeneity among studies—in terms of excavation protocols, operator experience, and outcome measures—limits the generalizability of findings and hinders the establishment of definitive clinical guidelines.

To address these limitations, future research should focus on large-scale, randomized controlled trials with standardized diagnostic criteria, consistent operator training, and long-term follow-up. Patient-centered outcomes, including restoration survival, quality of life indicators, and cost-effectiveness, should be incorporated into study designs to enhance their clinical relevance. Moreover, the impact of factors such as the specific type of caries detector used, manual vs. rotary excavation techniques, and clinician expertise warrants further investigation to optimize selective caries removal strategies. The use of magnification tools, such as dental operating microscopes or magnifying loupes, may also contribute to greater precision by enabling the detection of minimally demineralized areas not visible to the naked eye. This could help reduce the risk of inadvertent pulp exposure or excessive removal of sound tissue. Additionally, conventional pulp sensitivity tests frequently employed in clinical settings do not reliably reflect the true inflammatory status of the pulp, further emphasizing the need for improved diagnostic strategies in the management of deep carious lesions.

Although this review has focused primarily on caries detector dyes and laser fluorescence systems, the potential synergy between these diagnostic tools and optical magnification warrants a more detailed discussion.

Koç Vural et al. (40) provided direct evidence supporting the added value of magnification. Their study compared visual inspection with and without magnifying glasses to fluorescence-aided caries excavation (FACE), showing that magnification significantly enhanced residual caries detection. Residual lesions were identified in 46.5% of cases using FACE, compared to only 31.8% with unaided visual inspection.

Despite this, most studies evaluating caries detector dyes do not specify whether magnification was employed during clinical assessment. For instance, Peskersoy et al. (39) and Sadasiva et al. (41) examined the efficacy of dyes and fluorescence systems but did not indicate the use of magnification, limiting our understanding of the dyes' full diagnostic potential. This methodological omission may result in an underestimation of the accuracy of dye-based diagnostics when used without enhanced visualization.

Moreover, evidence suggests that magnified visualization may not only complement but potentially rival laser fluorescence systems. Clinical scenarios have demonstrated that suspicious areas overlooked under normal vision become evident under dental operating microscopes, and when combined with dye application, allow for more targeted tissue removal. These findings highlight the diagnostic value of magnification-assisted techniques, particularly when paired with chemical indicators.

Further research is needed to specifically assess the performance of caries detector dyes under magnification and compare such combined strategies to advanced technologies like DIAGNOdent. Standardizing protocols that incorporate enhanced optical tools could improve the precision and consistency of selective caries removal, providing an effective and potentially more accessible alternative to fluorescence-based diagnostics.

From a therapeutic perspective, incorporating fluorescence-based methods could enhance the standardization of selective caries removal, reducing the risk of pulp exposure and unnecessary tissue loss. Given that permanent teeth require long-term restorative strategies, optimizing diagnostic precision is critical for ensuring restoration durability and pulp vitality. Although fluorescence-based techniques show promise in permanent dentition, further high-quality research is needed to develop robust clinical guidelines. Large-scale randomized controlled trials should evaluate their long-term efficacy, considering patient-specific variables and standardized protocols. Integrating these methods into clinical practice could improve diagnostic reliability and lead to more predictable treatment outcomes in restorative dentistry. Long-term follow-up studies, such as that by Kanar et al. (2024), provide valuable data on restorative longevity and medium-term outcomes but face limitations such as patient attrition and uncontrolled variables like oral hygiene habits. Conversely, studies with shorter follow-up periods, such as those by Sadasiva et al. (41) and Koç Vural et al. (40), yield immediate and specific results on diagnostic performance but do not adequately address long-term impact.

These factors influence the observed outcomes and should be considered in future investigations. While meta-analyses are critical for consolidating scientific evidence, the number of comparative studies retrieved in this review remains modest. Alternative methodological approaches could help fill existing gaps. Furthermore, variables related to caries removal procedures, including the type of detector used, excavation technique, and clinician experience may affect outcomes and should be systematically addressed in future reviews. Integrating advanced technologies such as laser fluorescence into clinical practice has the potential to significantly improve outcomes, particularly in cases where the preservation of healthy tissue is critical. Nonetheless, implementation must account for factors such as device cost, availability, and the associated learning curve. A combined diagnostic approach may offer a balanced solution, maximizing diagnostic efficacy while mitigating the limitations inherent to individual techniques.

Although studies conducted in primary dentition dominate the literature, available evidence suggests that fluorescence-based techniques and caries detector dyes are equally effective in permanent teeth. Given the structural and functional differences between primary and permanent dentition, it is essential to further investigate long-term outcomes in adult populations. Ensuring diagnostic accuracy in permanent teeth is crucial for maintaining pulp vitality and optimizing restorative success, reinforcing the need for continued clinical trials. The validation and integration of fluorescence-based methods into standardized clinical protocols is essential to enhance diagnostic reliability, optimize restorative outcomes, and ensure the longevity of restorations in permanent dentition.

In addition to reporting diagnostic performance, it is crucial to critically assess the practical limitations and clinical implications. Although laser fluorescence systems generally show superior sensitivity and specificity, their performance can be influenced by extrinsic staining, hydration levels, and variations in calibration, potentially leading to false positives or inconsistent readings. On the other hand, caries detector dyes, while simpler and more cost-effective, are prone to overstaining, which may result in overtreatment and unnecessary dentin removal—especially when used without magnification or objective thresholds. This comparative analysis highlights the trade-off between accessibility and diagnostic accuracy. The combined use of dyes and fluorescence has shown promise yet lacks standardized protocols and long-term clinical validation. Therefore, future directions should aim to refine existing methods by incorporating visual enhancement tools, improving diagnostic selectivity, and developing integrative approaches that overcome the individual weaknesses of each modality. Such critical evaluation not only enhances the scientific depth of this review but also provides clinicians with a more nuanced understanding of the tools available for minimally invasive caries management.

A combined approach utilizing fluorescence–based systems together with visual aids, such as magnification, may provide the most balanced strategy enhancing diagnostic accuracy while minimizing unnecessary dentin removal and overtreatment in deep carious lesions. Clinical decision–making protocols for selective caries removal in different scenarios are summarized in Table 4.