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Year : 2021  |  Volume : 33  |  Issue : 3  |  Page : 149-152

Spectrophotometric analysis of crown discoloration induced by various intracanal medicaments: An in vitro study

Department of Conservative Dentistry and Endodontics, Vydehi Institute of Dental Sciences and Research Centre, Bengaluru, Karnataka, India

Date of Submission11-Jun-2021
Date of Decision01-Jul-2021
Date of Acceptance04-Sep-2021
Date of Web Publication30-Sep-2021

Correspondence Address:
Dr. Amishi Amit Parikh
Rajiv Gandhi University of Health Sciences, Bengaluru, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/endo.endo_59_19

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Aim: The aim of the study was to assess discoloration potential of four different intracanal medicaments.
Materials and Methods: Thirty single-rooted extracted bovine incisors were sectioned to a standardized root length, accessed, instrumented, and placed with temporary filling and cotton pellet. The specimens were divided into five groups (n = 6): Control group with no intracanal medicament and four groups with the following medicaments, i.e., calcium hydroxide (Ca(OH)2), calcium hydroxide with chlorhexidine (Ca(OH)2 with CHX), triple antibiotic paste (TAP), and silver diamine fluoride (SDF), respectively. Calorimetric evaluation, according to CIE L*a*b* system, was performed at pretreatment, on day 1, 7, 14, and 21. Data were analyzed using One-Way ANOVA and Repeated ANOVA. P <0.05 was considered statistically significant.
Results: The greatest color change (ΔE*) was observed at day 21 in TAP group (P < 0.001) followed by SDF group (P < 0.013), whereas Ca(OH)2 and Ca(OH)2 with CHX groups did not induce visible coronal discoloration.
Conclusions: Ca(OH)2 and Ca(OH)2 with the CHX groups showed the smallest coronal discoloration during the experimental time, whereas TAP and SDF groups showed the highest coronal discoloration.

Keywords: Calcium hydroxide, chlorhexidine, discoloration, silver diamine fluoride, spectrophotometer, triple antibiotic paste

How to cite this article:
Parikh AA, Nirupama D N, Naveen D N, Sindhu J, Nainan MT. Spectrophotometric analysis of crown discoloration induced by various intracanal medicaments: An in vitro study. Endodontology 2021;33:149-52

How to cite this URL:
Parikh AA, Nirupama D N, Naveen D N, Sindhu J, Nainan MT. Spectrophotometric analysis of crown discoloration induced by various intracanal medicaments: An in vitro study. Endodontology [serial online] 2021 [cited 2022 May 22];33:149-52. Available from: https://www.endodontologyonweb.org/text.asp?2021/33/3/149/327270

  Introduction Top

Tooth discoloration is the most common side effect seen in endodontically treated teeth.[1] Tooth discoloration is related to the contact period of the material to the tooth structure and the potential chromogenicity of the materials used in the treatment.[2] The common causes of discoloration are pulpal hemorrhagic products, residual pulpal tissue, intracanal medicaments, obturating, and temporary filling materials.[3] Although calcium hydroxide is the most widely used intracanal medicament for decades, it has limited effectiveness in the complete elimination of microorganisms from the root canal system.[4],[5]

Studies have shown that, when calcium hydroxide is mixed with chlorhexidine (CHX), the antimicrobial activity is increased.[6] When triple antibiotic paste (TAP) containing minocycline is used, promising results are seen in terms of antimicrobial activity. However, it presents with discoloration of the coronal tooth structure.[7] Another effective intracanal medicament is silver diamine fluoride (SDF) against E. faecalis, but it shows a black staining of teeth when used to arrest the carious lesions.[8],[9],[10]

Extensive research of existing literature did not reveal any study investigating crown discoloration induced by SDF and its comparison with other intracanal medicaments. Therefore, this study uses a spectrophotometric technique to assess the coronal discoloration potential of different intracanal medicaments. The null hypothesis of this study is that the tested intracanal medicaments would not affect the color of the crown.

  Materials and Methods Top

Specimen preparation

Thirty single-rooted bovine incisors were collected and immersed in 0.5% Chloramine-T disinfectant solution (Merck, Darmstadt, Germany) for 48 h. Teeth were selected based on the average sum of their buccolingual and mesiodistal dimensions; the distance between the root canal wall and external root surface measured using a digital vernier caliper. The pulp tissue was removed, and irrigation was done with 10 ml 5.25% sodium hypochlorite (NaOCl), 10 ml 17% ethylene diamine tetraacetic acid (EDTA) for 2 min each followed by 10 ml distilled water. After drying with cotton, the pulp chamber was filled with temporary filling material (Cavit TM G, 3M ESPE, Germany) sealing up to 2 mm apical to the cement enamel junction (CEJ). A cotton pellet was placed loosely on the temporary filling material.

The specimens were randomly divided into five groups (n = 6), and intracanal medicament was placed into the canals [Table 1].
Table 1: Distribution of experimental materials

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After placing the medicament in the canal, the apical openings were sealed with sticky wax. All the steps were performed from the apical aspect. Samples were stored at 100% humidity in an incubator at 37°C for 3 weeks.

Color measurement

In a dark room, color measurements were recorded pretreatment (pretreatment T0), at day 1 (T1), 7 (T7), 14 (T14), and 21 (T21), respectively, after placement of the medication. The color of each specimen was assessed by the CIE L*a*b* (Commission Internationale L'Eclairage, 1978) system using a spectrophotometer (Vita Easyshade Advance, VITA Zahnfabrik, Bad Sackingen, Germany) on the buccal surfaces of the crown. To standardize the color measurement, a circular tape of diameter 6 mm with a hole in the middle was bonded to the buccal surface of the crown 2 mm coronal to the CEJ [Figure 1]. The spectrophotometer was calibrated according to the manufacturer's instructions. Color measurement was performed three times, and the mean was calculated. L* represents the value of lightness or darkness, a* represents the measurement along the red-green axis, and b* represents the measurement along the yellow-blue axis. The total color differences (E*) were calculated using the following formula:[11]
Figure 1: Circular strip on the buccal surface of the crown above the cement enamel junction

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Statistical analysis

The L*, a*, and b* parameters of the samples were measured and compared to the pretreatment values. Descriptive statistics were represented with mean and standard deviation. ANOVA test was used to find significance among the groups. Repeated ANOVA was used to find significance in follow-up (within the group). P < 0.05 was considered statistically significant.

  Results Top

The experimental groups did not have significantly different baseline L* (P = 0.966), a* (P = 0.900), and b* (P = 0.499). Interactions between time and materials demonstrated a significant effect on the values (ΔE*) in each experimental groups (P < 0.001, P < 0.009, P < 0.001, and P < 0.013) except the control group (P = 0.139) [Figure 2]. SDF and TAP induced visible coronal discoloration, whereas Ca(OH)2 and Ca(OH)2 with CHX groups did not induce visible coronal discoloration [Figure 3].
Figure 2: The color change at different time periods in the groups. Group A: Control, Group B: Ca(OH)2, Group C: Ca(OH)2 with CHX, Group D: TAP Group E: SDF

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Figure 3: Discoloration of teeth on 21st day. Group A: Control, Group B: Ca(OH)2, Group C: Ca(OH)2 with CHX, Group D: Triple Antibiotic Paste, Group E: Silver Diamine Fluoride

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  Discussion Top

The primary objective of this study was to assess the discoloration potential of four different intracanal medicaments.

In the present study at day 1, experimental groups, i.e. Ca(OH)2, Ca(OH)2 with CHX, TAP, and SDF did not induce statistically significant coronal discoloration. The evaluated endodontic filling materials provided ΔE* values higher than 3.7, which is the clinical threshold for acceptability of color differences,[12] except the Ca(OH)2 group on day 1. The highest level of coronal discoloration occurred in the teeth filled with TAP reaching ΔE* =20.32 on day 21. The results of our study are in accordance with Akcay et al.[13] Their results indicated that TAP with amoxicillin induced severe color changes from week 1 of evaluation. The mechanisms by which TAP induces coronal tooth discoloration is binding of minocycline to the calcium ions through chelation.[14],[15],[16] Interestingly, in our study, teeth filled with SDF also resulted in clinically visible crown discoloration, reaching ΔE* =16.18 on day 21. The mechanisms by which SDF impacts coronal tooth discoloration may relate to silver deposits at tubular orifices after removal of the smear layer.[17],[18],[19] However, there are no previous study data to compare coronal discoloration of Ca(OH)2, Ca(OH)2 with CHX, TAP, and SDF when used as intracanal medicament.

The rationale behind choosing bovine teeth to assess discoloration by various intracanal medicaments was based on the study by Schilke et al.,[20] who reported that, in bovine teeth, the number of dentinal tubules in coronal dentin did not significantly differ from the dentin of human teeth. In our study, all the procedures were performed from the apical aspect to avoid coronal microleakage of the intracanal medicament and prevent disruption of the intact crown.[14],[21] Using #45 H file, the pulp was removed in toto from the apical aspect. Moreover, to remove any remaining pulp tissue in the chamber, 5.25% NaOCl and 17% EDTA were used for irrigation.[22] This was more predictable in the bovine model, which is another reason for the use of bovine teeth.

In this study, a digital spectrophotometer was used to register tooth shades at the different experimental phases. The spectrophotometer is commonly used for the measurement of transmitted or reflected light and moreover is suitable for color analysis of convex and asymmetric objects such as teeth[23],[24] and are the reference tools for color assessment.[25],[26],[27]

  Conclusion Top

Within the limitation of the study, intracanal placement of Ca(OH)2 and Ca(OH)2 with CHX groups did not induce clinically visible crown discoloration until day 21, whereas TAP and SDF groups induced clinically visible crown discoloration from day 7 onward, after placement. Further studies are required on various substitutes and techniques so that the clinician can make an informed decision regarding the use of intracanal medicament, striking the right balance between the degree of coronal discoloration and antimicrobial efficacy, especially in teeth present in the esthetic zone.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Krastl G, Allgayer N, Lenherr P, Filippi A, Taneja P, Weiger R. Tooth discoloration induced by endodontic materials: A literature review. Dent Traumatol 2013;29:2-7.  Back to cited text no. 1
Parsons JR, Walton RE, Ricks-Williamson L. In vitro longitudinal assessment of coronal discoloration from endodontic sealers. J Endod 2001;27:699-702.  Back to cited text no. 2
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Gomes BP, Vianna ME, Zaia AA, Almeida JF, Souza-Filho FJ, Ferraz CC. Chlorhexidine in endodontics. Braz Dent J 2013;24:89-102.  Back to cited text no. 6
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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]


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