| Abstract|| |
Aim: The aim of this study was to assess color changes in teeth and two different composite resins under the influence of chlorhexidine (CHX) with and without anti-discoloration system (ADS).
Materials and Methods: A total of 20 extracted human premolar teeth for periodontal and orthodontic purposes were selected for the study. Further, a total of 40 composite specimens comprising 20 each nanoceramic and nanohybrid composite disks of size 10-mm diameter and 0.5-mm thickness were prepared on a customized model for standardization using the composite filling instrument. The specimens were cured with light-curing unit for 20 s and polished with a composite polishing kit. Two mouthrinses comprising CHX and CHX with ADS were used. Baseline color values of natural tooth and two composite resins were recorded using an ultraviolet spectrophotometer. After baseline spectrophotometric measurements, all the samples were subjected to the mouthrinses. The postimmersion color values of the samples were then recorded, respectively, using the same spectrophotometer.
Statistical Analysis Used: The statistical analysis was done using paired t-test.
Results: Reflectance values showed a statistically significant difference between CHX and CHX with ADS among nanoceramic and nanohybrid composite samples. There was no statistically significant difference in reflectance values among natural teeth samples with either CHX or CHX with ADS.
Conclusion: Within the limitations of the current study, CHX with ADS may aid in avoiding stains caused due to use of CHX mouthwash, thereby making it more acceptable for patients.
Keywords: Anti-discoloration system; chlorhexidine mouthrinse; color stability; composite resin; spectrophotometer
|How to cite this article:|
Jaganath BM, Krishnegowda SC, Rudranaik S, Beedubail SP. Assessment of color changes in teeth and composite resins under the influence of chlorhexidine with and without anti-discoloration system: An in vitro study. J Conserv Dent 2023;26:52-5
|How to cite this URL:|
Jaganath BM, Krishnegowda SC, Rudranaik S, Beedubail SP. Assessment of color changes in teeth and composite resins under the influence of chlorhexidine with and without anti-discoloration system: An in vitro study. J Conserv Dent [serial online] 2023 [cited 2023 Feb 5];26:52-5. Available from: https://www.jcd.org.in/text.asp?2023/26/1/52/362916
| Introduction|| |
Restorative dentistry is constantly evolving with the advancement in the field of dental materials. The surge for esthetic enhancement is the main reason behind the advent of various materials in dentistry. Various composites have come in the market with alterations in its technology to meet the esthetic demand. Yet, the color stability of these restorative materials in a dynamic oral environment is an important criterion influencing its clinical longevity which still continues as an inherent challenge to the material. Discoloration of composite resin may occur due to several extrinsic and intrinsic factors. Intrinsic factors include dimensions of filler particles, depth of polymerization, and coloring agents. Extrinsic factors include oral hygiene status, the presence of surface roughness, dietary habits, smoking, beverages, and mouthrinses.
Mouthrinses are the commonly prescribed chemical plaque control agents. They are adjunct to the mechanical means for prevention and control of caries, periodontal diseases, for the cessation of plaque, and help in diminishing oral malodor. Although mouthrinses being antibacterial and has a lot of advantages, it has disadvantages too. The etiology for discoloration of composites is multifactorial, of which proprietary mouthrinse is one of the causative factors. They are available as alcohol- and nonalcohol-based mouthrinses. The low pH of the mouthrinse may influence the hardness, wear, and color stability of composites. According to the literature, the staining side effect associated with chlorhexidine (CHX) use is attributed to Maillard reaction, the formation of pigmented metal sulfides, and reactions between polyphenols and tannin from food and drinks and CHX itself.
To combat the tooth staining disadvantage of CHX, CHX with anti-discoloration system (ADS) was introduced in the market. This new mouthrinse, which contains CHX along with ADS, promises to prevent plaque formation and also avoids staining of the tooth. This composition contains Plasdone K-29/32 which is known to prevent staining. Plasdone K-29/32 is known to be a water-soluble, high molecular weight homopolymer of vinylpyrrolidone that has been designed as an anti-discoloration agent to reduce discoloration.
Since color stability of composite still remains a long-term clinical problem, this study was carried out to assess color changes in teeth and composite resins under the influence of CHX with and without ADS using an ultraviolet (UV) spectrophotometer.
| Materials and Methods|| |
Twenty extracted human premolar teeth for periodontal and orthodontic purposes were selected for the study. They were collected, stored, sterilized, and handled according to the Occupational Safety and Health Administration and the Centre for Disease Control and Prevention Guidelines. A total of 40 composite specimens were prepared. It comprised 20 each nanoceramic and nanohybrid composite disks of size 10-mm diameter and 0.5 mm thickness. Samples were prepared on a customized model for standardization using the composite filling instrument (GDC Composite Filling Instrument). The thickness was confirmed using a vernier caliper. The specimens were cured with light-curing unit (LEDition Polymerization Unit, Ivoclar Vivadent AG, Liechtenstein) for 20 s and polished with composite polishing kit (Shofu). CHX (Hexidine, ICPA Health Products) and CHX with ADS (Clohex™ ADS, Dr. Reddy's Laboratories Ltd) were used in the study.
Specimens were divided into the following groups for the study purpose.
- Group I (n = 20): nanohybrid composite disks (3M ESPE, St. Paul, USA)
- Group II (n = 20): nanoceramic composite disks (Ceram.x SphereTEC, Dentsply, Konstanz, Germany)
- Group III (n = 20): natural tooth
- Further, each group was subdivided into two subgroups, namely A and B, containing ten samples each. Samples under the A subgroup from each group were subjected to CHX with ADS and samples under the B subgroup from each group were subjected to CHX without ADS.
The prepared samples were immersed in distilled water in separate containers and incubated at 37°C for 24 h. After 24 h, baseline color values of each sample were recorded using a UV spectrophotometer (190 to 3200 nm, UV-VIS-NIR/DRS, LAMBDA 750, PerkinElmer). The reflectance values were recorded at 400 and 700 nm. Following baseline color measurements, the samples were subjected to mouthrinses. Specimens from each group were immersed in 0.2% chlohex–ADS mouthrinse and 0.2% CHX mouthrinse, respectively, for 1 min twice daily for 21 days. Between exposures to the mouthrinses, samples were stored in artificial saliva (Wet Mouth, ICPA Health Products) at 37°C. Storage media was changed after every exposure of the sample to the mouthrinses. Postimmersion color values of the samples were then recorded, respectively, using the same spectrophotometer at 400 and 700 nm [Figure 1].
|Figure 1: Samples tested in UV spectrophotometer (190 to 3200 nm, UV-VIS-NIR/DRS, Lambda 750, Perkin Elmer. UV: Ultraviolet|
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The data were collected, tabulated, and subjected to statistical analysis.
Descriptive statistics were calculated. Test of normality indicated the normal distribution of the data. Paired t-test was used for comparison between the groups.
| Results|| |
The present study revealed that there was a statistically significant difference between baseline and postexposure to mouthrinse in reflectance values of light among both Group I and Group II under the influence of CHX at 400 and 700 nm. Samples subjected to CHX-ADS showed no statistically significant difference between baseline and postexposure to mouthrinse in reflectance values of light at both wavelengths. Group III showed no significant changes in reflectance values of light under the influence of either CHX or CHX –ADS mouthrinse [Table 1].
|Table 1: Comparison of reflectance values of light at baseline and postexposure to mouthrinses at two different wavelengths among the groups|
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| Discussion|| |
There is a strong body of evidence in support of CHX mouthrinse but one of the most prominent side effects is tooth staining. The occurrence of staining could influence the compliance of the patient in regard to the proper use of CHX. CHX with ADS contains a patented ingredient Plasdone K-29/32, which is known to be a water-soluble, high molecular weight homopolymer of vinylpyrrolidone that has been designed as an anti-discoloration agent meant as an additive in CHX to reduce discoloration. Plasdone K-29/32 acts by binding to stain-causing chemicals and increases stain solubility and result in the removal of stains. Plasdone is known to be nonoxidative as it is neither peroxide-based nor a peroxide generator and is nonabrasive.
The color changes can be assessed using various instruments including spectrophotometer and colorimeter. In this study, we have used a spectrophotometer because it is considered to be more accurate in measuring color change. The spectrophotometer used in this study (UV-visible-NIR Spectrophotometer with diffuse reflectance, Perkin Elmer, Lambda 750, USA) has a measurement range of 190–3200 nm. For the purpose of analysis of color changes in our study, a wavelength range of 400–700 nm was utilized and reflectance values were noted at the limits of 400 and 700 nm of the visible light spectrum.
Tooth color is dependent on the reflectance and absorbance properties of the tooth, which are influenced by layers of the tooth – enamel, dentin, and pulp. When light irradiates on the tooth surface, some of the light is reflected on the surface. Part of the incident light is absorbed by the pigmented proteins and other colored stains in the tooth. Thus, chromogen concentration is an important factor in determining the degree of absorption in the tooth. The reflected or transmitted light will change as the concentration of chromogen in the tooth changes. Therefore, in this study, the reflectance of irradiated light was used as a measure of discoloration of teeth and composite resins.
Among the composite resins tested in our study, the magnitude of decrease in reflectance values was more pronounced in nanoceramic composite resins when compared to nanohybrid composite resins. This is in alignment with previous studies conducted by Jung et al., Celik et al., and Shree Roja et al. where the reason for color changes in nanoceramic composites can be related to structural difference, low volumetric filler content of the material, and porosities detected which led to more retention of stains.,,
The discoloration was also observed in nanohybrid composites under the influence of CHX which can be attributed to large filler particles which are more susceptible to discoloration and water absorption and the effect of coloring agents on the quality of the bond between the matrix and filler which can cause discoloration.
On contrary, Maran et al. in their systematic review and meta-analysis revealed that meta-analyses of color matches failed to show differences between the different types of composites in any of the study follow-ups. This can be attributed to the difference in study designs which includes measurement methods, the protocol of exposure to mouthrinse used, time period, temperature, and surface characteristics of the samples. To mimic the real-life scenario, this study was conducted for 21 days, with exposure of samples to mouthrinse for 1 min to 12 h interval in a day and further stored in saliva substitute at 37° temperature.
| Conclusion|| |
Within the limitations of the study, it can be concluded that although in lesser magnitude, composite resins exhibit discoloration with the use of CHX mouthrinse alone at a 21-day period. In vitro assessment of natural teeth without the influence of any dietary or salivary constituents did not exhibit significant discoloration with the use of CHX mouthrinse at a 21-day period. It would be wiser to prescribe CHX with ADS to patients so as to avoid staining caused due to use of CHX mouthrinse, making it more acceptable for patients.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Dr. Siri Parvathi Beedubail
Department of Conservative Dentistry Endodontics, Sri Hasanamba Dental College and Hospital, Vidyanagar, Hassan - 573 202, Karnataka
Source of Support: None, Conflict of Interest: None