## 1 Introduction  
The dental caries diagnosis is completely subjective, less reproducible, and based on the dentin consistency and in its color [1]. The removal of carious tissue is the main purpose of dental treatment that includes preserving the sound tooth structure and vitality of the pulp [2]. The successful restoration of a carious tooth depends upon the excavation of all the affected tissue so that secondary caries can be prevented by providing a sound structural base for the restoration [3]. This procedure is assessed conventionally using a mouth mirror and an explorer but the visual and tactile method of assessing the carious lesion may be skewed so it is difficult to judge when to stop the excavation. Recently, the clinical management of dental caries has followed the concept of minimal intervention (MI) [4; 5; 6]. The basis of MI is restoring the cavitated carious lesion with minimal intervention and remineralization of the noncavitated lesion as proposed by the FDI (Federation Dentaire Internationale) in 2000 [7]. Dentinal caries is mainly categorized in two layers as inner and outer layer [8; 9], and the previous literature has shown that the destruction of collagen fibers in the outer layer cannot be remineralized, but the inner layer can be remineralizedwith prompt treatment [10; 11; 12]. However, the caries removal once again caries an individual variation in the dentists based on their previous experience, change in color and dentin hardness [13; 14; 15; 16]. In clinical trials done in the United States [17] and United Kingdom [18] that assess the use of dyes in cavities prepared by dental students and assessed by clinical instructors it was revealed that the judgment of the instructors was often flawed, and that there was still some residual decay. On this background, propylene glycol and acid red were used to develop a caries detector dye as an objective index for the diagnosis and removal of carious dentin [19; 20; 21]. The most common components of the caries detector dyes are a dye and a solvent like propylene glycol, and even though these caries detector dyes do not stain the bacteria in the carious lesion, they enable the identification of the infected dentin [22]. The solvent propylene glycol penetrates the loose collagen fibers in infected dentin which causes the staining of the degraded collagen fiber by the dyes. Since the caries detection dye only stains degraded collagen not the bacteria that causes the carious lesion, these dyes are used under the assumption that removing the degraded collagen will remove the bacteria causing the carious lesion [22]. Several studies have shown that these caries detection dyes may yield a false-positive staining of healthy cavity walls leading to the unnecessary removal of the intact dentin [23; 24; 25]. Nevertheless, a few investigations have revealed dyes may be beneficial in detecting caries, and its use during cavity preparation could aid in detecting carious tissues that may go undiagnosed by the clinician [26; 27]. It is now noticeably proven that dyes stain the dentin, which has an organic matrix of less mineralized structure, and not the bacteria [28]. [PERSON] and others compared and confirmed the mineral density at the site of dye stainable dentin and the lack of specificity of caries detector dyes [26]. The penetration of these caries dyes in the matrix of less mineralized dentin can result in the unnecessary removal of tooth structure especially in primary teeth which are usually less mineralized than permanent teeth. The innovation of adhesive resin systems and dentin bonding is among the most essential areas of study in operative dentistry. The resin present in the dentin bonding agent on polymerization flows into the demineralized enamel and dentine structure that forms micro/nano-mechanical interlocking resin tags to shield the dentine tubules.