| Abstract|| |
Aim: The aim of this in vitro study was to evaluate the effect of two different chemomechanical caries removal (CMCR) agents on dentin microhardness.
Materials and Methods: In this study, the crown portion of ten carious-free and ten caries-affected teeth were selected. In carious-free samples, the teeth were decoronated at the level of cemento - enamel junction. Only the crown portion of the teeth was selected. Occlusal one-third of the crowns were cross-sectioned and discarded to expose the dentin, and it was divided into two groups, five teeth in each group. Then, they were further sectioned longitudinally through the centre. In one group, no agent was applied on one half and Carisolv was applied on other half. In another group, no agent was applied on one-half and Carie-Care was applied on the other half for 1 min. In carious samples, the crowns were sectioned through the centre of carious lesion. Carisolv was applied on one-half and Carie-Care was applied on the other half. After using CMCR agents, surface hardness of dentin was examined using Vickers hardness number (VHN).
Statistical Analysis and Results: The data were analyzed using t-test and one-way analysis of variance (ANOVA). There were no significant difference among normal dentin (62.91 ± 2.76), Carisolv-treated normal dentin (61.72 ± 2.89), and Carie-Care-treated normal dentin (61.90 ± 3.19). In carious samples, the results of Carisolv-treated dentin (58.57 ± 2.62) was not statistically significantly different from those of the Carie-Care-treated dentin (56.77 ± 4.41).
Conclusion: In conclusion, neither of the CMCR methods caused a significant change in the microhardness of normal dentin and the treated carious dentin.
Keywords: Chemomechanical caries removal; carisolv; carie-care; dentin microhardness
|How to cite this article:|
Ramamoorthi S, Nivedhitha MS, Vanajassun P P. Effect of two different chemomechanical caries removal agents on dentin microhardness: An in vitro study. J Conserv Dent 2013;16:429-33
|How to cite this URL:|
Ramamoorthi S, Nivedhitha MS, Vanajassun P P. Effect of two different chemomechanical caries removal agents on dentin microhardness: An in vitro study. J Conserv Dent [serial online] 2013 [cited 2020 Jan 22];16:429-33. Available from: http://www.jcd.org.in/text.asp?2013/16/5/429/117520
| Introduction|| |
The main objective in treating carious lesions is to remove the infected layer, while leaving behind the affected dentin. The outer carious dentin is irreversibly denatured, infected, and non-remineralizable and must therefore be removed. The inner carious dentin is reversibly denatured, not infected, and remineralizable and must therefore be preserved.  In order to avoid the painful and unnecessary removal of healthy tooth structure, the differentiation between these layers is clinically relevant. 
Caries excavation has conventionally been performed according to the mechanical principles using drills and sharp-edged hand instruments. These methods, although often effective, have some major disadvantages that can result in heat, pressure, dentin desiccation, vibration, and pain.  First, due to apparent lack of objective clinical markers, the amount of dentin to be removed is often difficult to establish. Second, it often induces pain and discomfort; therefore, local anesthesia is needed.  To prevent these drawbacks, alternative dentin caries-removal methods have been proposed, including chemomechanical techniques, , air abrasion with aluminum oxide or glass particles,  sono-abrasion,  ultrasonic instrumentation,  and lasers.  The advantages of chemomechanical caries removal (CMCR) agents increased patient's compliance,  avoided usage of local anesthesia,  left the healthy dentin intact,  and facilitated ultimate tissue preservation. 
Chemomechanical method of caries removal was first based on the studies by Goldman and Kronman with the introduction of GK-101, followed by GK-101E in 1980, which was marketed as a Caridex system. Caridex system was eventually abandoned because of its lack of efficiency and convenience. Recently, the Carisolv system was introduced by Mediteam, Sweden. Carisolv system consists of two gels: One containing 0.95% sodium hypochlorite (NaOCl) and the other containing three amino acids (glutamic acid, leucine, and lysine), sodium chloride, carboxy-methyl-cellulose, sodium hydroxide, and water. In 2003, a Brazilian formulation named Papacarie was introduced, which is a gel based on papain, a proteolytic cysteine enzyme that has antibacterial and anti-inflammatory properties.  Thus, the Carie-Care system was introduced in India by Uni-Biotech Pharmaceuticals Pvt. Ltd., which consists of papaya extract (papain) 100 mg, clove oil 2 mg, colored gel (blue), chloramines, sodium chloride, and sodium methyl paraben, with similar property as that of Papacarie. Hence, the aim of this in vitro study was to evaluate the effect of two different CMCR agents on dentin microhardness.
| Materials and Methods|| |
Ten permanent molars with dentin caries and ten caries free molars extracted due to periodontal reasons in patient aged between 30 and 50 years were used in this study. The patients' teeth were stored in 0.1% thymol solution at room temperature to avoid dehydration and used within 2 weeks after extraction.
Preparation of carious-free samples
Carious-free teeth were decoronated at the level of cemento-enamel junction. Only the crown portion of the teeth were selected. Occlusal one-third of the crowns were cross-sectioned using a disk rotating at low speed. Occlusal one-third of the crown was discarded to expose the dentin, and it was divided into two groups, with five teeth in each group. Then, they were further sectioned longitudinally through the centre. In one group, no agent was applied on one-half and Carisolv was applied on the other half, according to the manufacture's instruction for 1 min. In other group, no agent was applied on one half and Carie-Care was applied on the other half according to the manufacturer's instruction, for 1 min. Next, they were rinsed thoroughly with distilled water and gently dried [Figure 1].
Preparation of carious samples
Carious lesions of brown to black color and resistant to probing but readily penetrated when tested with a sharp explorer were selected for this study. All lesions had no enamel coverage, and the dentin was easily accessible through the cavity. The teeth were decoronated at the level of cemento-enamel junction. Only the crown portion of teeth was selected, and it was further sectioned through the centre of carious lesion. Carisolv was applied on one-half and Carie-Care was applied on the other half, according to the manufacture's instruction, for 1 min. The caries was gently excavated using spoon excavator. The procedure continued for as long as the carious tissue could be removed. The prepared cavities were verified according to the color and hardness of the lesion by checking with a dental explorer until a sharp scratching sound was heard. 
All cavities were cross-sectioned perpendicular to the tooth axis at the occlusal third of the crown using a diamond wheel cutter with water cooling to avoid injury to the dentin and sections were smoothened with sandpaper (400 grit) [Figure 2].
Measurement of hardness
The sections were then embedded in a chemically cured acrylic resin so that the occlusal surfaces were exposed to the external surface. The blocks were soaked in thymol immediately at the dough stage of polymerization of the resin. At the doughy stage, the temperature rise as a result of auto-curing was very low and it did not affect the tooth tissues.  After polymerization, each block was smoothed with sandpaper. The blocks were kept in distilled water containing 0.1% thymol at room temperature until hardness measurement was completed within 24 h.
Microhardness was measured with a Vickers hardness tester. The test was determined using a load of 1 Newton (100 g) applied to the specimens for 15 s.  The Vickers hardness numbers (VHNs) were measured at five points in dentin with a minimum distance of 40 μm. In the carious samples, VHNs were measured at 25 μm next to the cavity floor, which was considered as Carisolv/Carie-care-treated dentin.
For the carious samples, data were analyzed using t-test and a value of P ≤ 0.05 was considered significant. For the caries-free samples, t-test was used to compare between Carisolv-treated healthy dentin and Carie-Care-treated healthy dentin and analysis of variance (ANOVA) was used to evaluate any statistical difference between Carisolv-treated dentin, Carie-Care-treated dentin, and the control (P ≤ 0.05).
| Results|| |
The mean values of VHN was 62.91 ± 2.76 for the untreated dentin, 61.72 ± 2.89 for Carisolv-treated dentin, and 61.90 ± 3.19 for the Carie-Care-treated dentin. The microhardness of the dentin for the samples in which healthy dentin was treated with Carisolv and Carie-Care gel showed no significant difference as compared with the adjacent untreated dentin [Table 1] and [Table 2].
|Table 1: One-way ANOVA to compare the mean hardness among healthy dentin, Carisolv on healthy dentin, and Carie-care on healthy dentin|
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|Table 2: Independent samples t-test comparison of mean hardness between Carisolv and Carie-care in healthy dentin|
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The results revealed that the VHN of the cavity floor prepared by Carisolv was 58.57 ± 2.62, which did not differ statistically significantly from the VHN of the cavity floor prepared by Carie-Care (56.77 ± 4.41) [Table 3].
|Table 3: Independent samples t-test comparison of mean hardness between Carisolv and Carie-care in decayed teeth|
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| Discussion|| |
This in vitro study evaluated the efficacy of two chemomechanical carious removal agents, namely Carisolv system and Carie-Care system.
Carisolv contains NaOCl, which breaks the cross-links between the dentinal collagen fibrils by denaturing them and dissolving the necrotic tissue. The bond between NaOCl and the amino acids reduces the effect of whole collagen denaturation and breaks only the bond between the affected collagen fibrils, without causing any molecular alterations. Carisolv removes only the non-remineralizable infected and necrotic dentin, preserving the affected dentin layer  and not causing harm to the healthy dentin surrounding the lesion. 
Carie-Cáre, a gel based on papain and containing chloramines, similar to Papacárie ® (Fórmula and Ação, São Paulo SP, Brazil) is less costly than Carisolv and has similar use, indication, and CMCR efficiency.  Papain, a papaya extract has antibacterial and anti-inflammatory properties  and also acts as a debris-removing agent. It does not harm healthy tissues and promotes tissue healing and acts only on carious tissue, which lacks plasmatic protease inhibitor alpha-1-antitrypsin; its proteolytic action is inhibited on healthy tissue because healthy tissue contains this substance.  Chloramines help in the healing process and shorten tissue repair time and have the potential of dissolving carious dentin by means of chlorination of partially degraded collagen. This helps in disruption of collagen structure, dissolves hydrogen bonds, and helps in tissue removal.  Clove oil has an analgesic and antiseptic action. Sodium methyl paraben is used as a preservative.
CMCR involves softening of carious dentin using chemicals, followed by the removal of carious dentin with instruments similar to excavators. Along with Carisolv system, a specialized set of instruments were supplied.  However, in our study, we did not use any specialized instruments for removing carious dentin after Carisolv application. In order to standardize the excavation, in both the cases, spoon excavators were used to remove the carious dentin.
Microhardness of tooth can be checked by three ways, namely, Knoop's Hardness number (KHN), VHN, and Brennel's hardness number (BHN). In this study, VHN test was used instead of KHN test as it was proposed that the Vickers indenter should always be used in tooth hardness test  and square shape of indent obtained in VHN was easy and more accurate to measure the tooth hardness. 
Collys et al., suggested a load of 50 g and more for studies of hardness in teeth, because they found that lower loads influence the indentation size. Qasim et al.,  recommended a load of 100 g, because it gave a clear indentation to be observed under microscope. Therefore, in this study, a load of 100 g was used and kept constant for all the samples.
Hossain et al.,  evaluated the removal of carious dentin by the Carisolv system and found that there were no significant differences between the quantities of calcium content (Ca weight %), phosphorus content (P weight %), and the Ca/P weight ratio of Carisolv cavities with that of the adjacent healthy dentin (P < 0.01). KHN test of the Carisolv cavity floor was almost similar to that of the adjacent healthy dentin. This suggests that Carisolv does not have any adverse effects on the dentinal compositions.
The results in our study also showed that CMCR agents did not affect microhardness of healthy dentin and also there were no significant difference between the two different agents on the carious dentin. This suggests that Carisolv and Carie-Care does not have any adverse effects on healthy and treated carious dentin.
The result indicates that Carisolv and Carie-Care do not produce any adverse side effects on dentin microhardness. Therefore, cavity preparation with these agents provides a clean dentin surface without affecting the adjacent healthy dentin. Although Carie-Care and Carisolv present a potential to be used in caries excavation, these products, particularly Carie-Care, that is more recent in the market, needs further laboratory and clinical investigation to evaluate their efficacy, and its effects such as bond strength of restorative materials to dentin surface.
| Conclusion|| |
In conclusion, neither of the CMCR methods causes a significant change in the microhardness of healthy dentin and the treated carious dentin.
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Department of Conservative Dentistry and Endodontics, Saveetha Dental College, Saveetha University, 162, PH Road, Velappanchavadi, Chennai - 600 077, Tamil Nadu
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]