Original Article COLOUR STABILITY OF COMPOSITE RESINS IN THE PRESENCE OF HERBAL TEAS: A SPECTROPHOTOMETRIC STUDY GOWRISH S. , VANDANA SADANANDA * , MURTAZA HATIM ZAKIYUDDIN Department of Conservative Dentistry and Endodontics, Deralakatte, Mangaluru-575018, Karnataka, India * Corresponding author: Vandana Sadananda; * Email: drvandanasadananda@nitte.edu.in Received: 21 Mar 2025, Revised and Accepted: 24 Jun 2025 ABSTRACT Objective: This study aimed to evaluate and compare the effects of four herbal teas, Amla (Emblica officinalis ), Hibiscus (Hibiscus sabdariffa), Moringa (Moringa oleifera), and Tulsi (Ocimum sanctum) on the colour stability of three composite restorative materials, nanohybrid composite resin, bulk-fill flowable composite and nanohybrid composite resin with SphereTEC fillers, over 60 d using spectrophotometric analysis. Methods: A total of 150 disc-shaped composite specimens were fabricated and divided into three groups: Nanohybrid composite resin (Group I), bulk-fill flowable composite (Group II) and nanohybrid composite resin with SphereTEC fillers (Group III). Each group was further divided into five subgroups (n=10), which were immersed daily in Amla, Hibiscus, Moringa, Tulsi tea, and in artificial saliva (control), for 15 min over 60 d. Colour changes were assessed at baseline, day 30, and day 60 using a digital reflectance spectrophotometer, and ΔE* values were calculated according to the CIELAB system. Results: At day 60, Tulsi tea induced the highest discolouration across all composite resins, with mean ΔE values of 36.21±0.37 (Group I), 37.39±0.40 (Group II), and 37.83±0.60 (Group III). Hibiscus and Amla teas also produced notable staining (ΔE up to 34.29), while Moringa tea caused the least discolouration (ΔE ≈ 30). The artificial saliva subgroups remained near baseline (ΔE<30). No statistically significant differences (p > 0.05) were observed between composite resin types, indicating that resin matrix hydrophilicity may play a more dominant role than filler morphology in staining susceptibility. Conclusion: Herbal teas demonstrated a potential for staining composite restorative materials, with Tulsi tea showing the greatest discolouration effect. These findings highlight the importance of material selection and patient counselling regarding dietary habits to maintain the aesthetic longevity of dental restorations. Keywords: Composite resins, Dental materials, Colour stability, Spectrophotometry, Dental Restoration, Permanent, Staining and discoloration, Herbal teas, Health education, Health Care, Global health, Knowledge © 2025 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/) DOI: https://dx.doi.org/10.22159/ijap.2025v17i5.54294 Journal homepage: https://innovareacademics.in/journals/index.php/ijap INTRODUCTION Composite resins have transformed restorative dentistry by offering superior aesthetics and functional durability [1]. Their ability to bond adhesively to tooth structures enables conservative cavity preparations and minimizes the risk of secondary caries. Additionally, composites can replicate the translucency and shade of natural dentition, making them ideal for anterior and posterior restorations [2]. However, maintaining their long-term colour stability remains a clinical challenge, as discolouration is a primary reason for restoration replacement. Discolouration of composites results from both intrinsic and extrinsic factors. Intrinsic changes involve oxidation of polymeric components, hydrolytic degradation of the filler-resin interface, and polymer aging due to thermal and enzymatic stress, leading to refractive index alterations and yellowing. Residual unreacted monomers can further oxidize over time, exacerbating internal discoloration [3, 4]. Extrinsic staining occurs via absorption or adsorption of chromogenic agents found in foods, beverages, and oral hygiene products. Surface roughness and porosity play crucial roles, with rougher surfaces retaining more pigments [5, 6]. Polishing protocols significantly influence this, as well; polished surfaces offer greater resistance to staining. Resin matrix hydrophilicity also contributes to water absorption, allowing deeper penetration of staining molecules. Composites with higher water sorption exhibit greater colour instability due to pigment diffusion through the water phase [7-9]. Studies have extensively evaluated the staining effects of coffee, black tea, red wine, and soft drinks, which are rich in chromogens like tannins and anthocyanins. These compounds interact with resins through hydrogen bonding and π-π interactions [10]. In contrast, the effects of herbal teas on composites remain underexplored, despite their growing popularity for health benefits. Herbal teas contain distinct bioactive compounds, hydrolysable tannins, flavonoids, anthocyanins, and chlorophylls that may interact differently with resin matrices [11]. Unlike black tea and red wine, which primarily contain condensed tannins and metal-polyphenol complexes, herbal teas have variable solubility profiles and chemical compositions. This biochemical distinction justifies the present investigation. The influence of herbal infusions, especially Tulsi, Amla, Hibiscus, and Moringa on composite resins warrants scientific attention given their increasing consumption in health-focused populations [12]. Contemporary composite technologies, such as nanohybrids and bulk-fills, offer improved optical and mechanical performance. Nanohybrids incorporate nanoscale and microscale fillers, enhancing polishability and reducing pigment adherence [14, 15]. Bulk-fill composites allow deep curing in a single increment due to advanced photoinitiators, but may be more prone to staining due to their higher resin content and larger filler particles. Sphere TEC-based composites use pre- polymerized spherical fillers for better handling and surface finish [16-19]. Despite these advancements, differences in filler systems may not overcome staining susceptibility if resin matrix composition remains hydrophilic. Herbal teas like Amla (Emblica officinalis), Hibiscus (Hibiscus sabdariffa), Moringa (Moringa oleifera), and Tulsi (Ocimum sanctum) contain plant-derived pigments and polyphenols capable of staining dental materials [20-23]. Their staining mechanisms may involve hydrogen bonding, van der Waals interactions, and complexation with polar resin groups [11, 24]. Fig. 1 illustrates key staining molecules. International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 17, Issue 5, 2025