Class V lesions represent a significant portion of restorative challenges in clinical dentistry due to their proximity to the gingival margin, involvement of enamel-cementum junction, and frequent association with non-carious cervical lesions [1]. Achieving durable marginal integrity in this region is complicated by polymerization shrinkage, occlusal stress concentration, and difficulties in moisture isolation [2]. Composite resins have evolved considerably with improved filler technology, bonding systems, and optical properties, making them the material of choice for esthetic restorations [3]. However, concerns persist regarding marginal microleakage resulting from polymerization contraction and elastic modulus mismatch [4]. Glass ionomer cements, on the other hand, offer chemical adhesion to tooth structure, fluoride release, and favorable thermal expansion characteristics [5]. Despite these advantages, inferior color stability and surface degradation over time remain major drawbacks [6]. Marginal microleakage has been directly linked to postoperative sensitivity, secondary caries, and restoration failure [7]. Similarly, color instability compromises esthetics and patient satisfaction, particularly in anterior and cervical regions [8]. Given the continuous evolution of restorative materials and conflicting evidence in the literature, a direct comparative evaluation of composite and glass ionomer restorations in Class V cavities is clinically relevant. This study aimed to assess and compare marginal integrity and color stability of these materials under standardized conditions [9,10].

Study Design A controlled in-vitro comparative study was conducted following institutional ethical clearance. Sample Selection Sixty freshly extracted, non-carious human premolars were collected and stored in 0.1% thymol solution until use. Teeth with cracks, restorations, or cervical defects were excluded. Cavity Preparation Standardized Class V cavities (3 mm × 2 mm × 2 mm) were prepared on the buccal surface using a high-speed handpiece under water coolant. Group Allocation • Group I (n = 30): Restored with light-cured composite resin • Group II (n = 30): Restored with conventional glass ionomer cement Restorations were performed according to manufacturer instructions and finished with standardized polishing protocols. Aging Procedure All samples underwent thermocycling (5,000 cycles between 5 °C and 55 °C) followed by immersion in staining solution. Evaluation Parameters • Marginal integrity: Assessed using dye penetration method and scored under stereomicroscope • Color stability: Evaluated using spectrophotometer and expressed as ΔE values Statistical Analysis Data were analyzed using SPSS software. Independent t-test and chi-square test were applied with p < 0.05 considered statistically significant.

Table 1 (Distribution of microleakage scores): The distribution of microleakage scores revealed a clear difference between the two restorative materials. A higher proportion of composite restorations exhibited score 0 (no dye penetration), whereas glass ionomer restorations showed a greater frequency of higher microleakage scores. This indicates that composite restorations achieved superior marginal sealing compared to glass ionomer restorations, with the difference being statistically significant (p < 0.01). Table 2 (Mean microleakage score comparison): The mean microleakage score was significantly lower in the composite group than in the glass ionomer group. This finding quantitatively confirms that composite restorations demonstrated better marginal integrity overall. The statistically significant difference (p < 0.01) suggests a more consistent adaptation of composite material to the cavity margins compared to glass ionomer cement. Table 3 (Mean ΔE values for color stability): Evaluation of color stability showed that composite restorations had significantly lower mean ΔE values compared to glass ionomer restorations. The color change observed in the composite group remained within clinically acceptable limits, while the glass ionomer group exhibited markedly higher discoloration after aging. This difference was highly statistically significant (p < 0.001). Table 4 (Percentage exceeding clinically acceptable ΔE): A substantially higher percentage of glass ionomer restorations exceeded the clinically acceptable ΔE threshold when compared with composite restorations. Only a small proportion of composite samples demonstrated perceptible color change, whereas the majority of glass ionomer samples crossed the acceptability limit, indicating inferior long-term esthetic stability. Table 1. Distribution of Microleakage Scores Between Groups Microleakage Score Composite (n=30) Glass Ionomer (n=30) p-value Score 0 18 (60%) 6 (20%) Score 1 8 (26.7%) 10 (33.3%) Score 2 4 (13.3%) 14 (46.7%) <0.01* Table 2. Mean Microleakage Score Comparison Group Mean ± SD p-value Composite 0.53 ± 0.62 Glass Ionomer 1.27 ± 0.78 <0.01* Table 3. Mean ΔE Values for Color Stability Group Mean ΔE ± SD p-value Composite 2.1 ± 0.6 Glass Ionomer 4.8 ± 1.1 <0.001* Table 4. Percentage of Samples Exceeding Clinically Acceptable ΔE Group ΔE > 3.3 (%) Composite 10% Glass Ionomer 63%

This comparative evaluation demonstrated that restorations placed with resin composite exhibited significantly better marginal integrity and superior color stability than conventional glass ionomer restorations in standardized Class V cavities. The observed difference in marginal integrity is clinically important because cervical margins frequently terminate on dentin/cementum, where adhesion is less predictable and contamination risk is higher, predisposing to marginal gap formation and subsequent microleakage-related failure pathways (postoperative sensitivity, marginal staining, and secondary caries) [1–3]. The superior marginal integrity in the composite group is biologically plausible. Contemporary adhesive strategies enable micromechanical and chemical interaction with enamel/dentin substrates, creating a hybrid layer and resin tags that can reduce interfacial leakage when technique sensitivity is controlled [2,4]. Although polymerization shrinkage remains a concern in resin-based materials, appropriate incremental placement, careful light-curing, and adequate bonding can mitigate stress concentration at the cervical margin [4,5]. Prior microleakage studies in Class V restorations using dye penetration methodologies commonly report comparatively lower leakage for resin-based restorations than for ionomer-based materials when bonding protocols are optimized [5–7]. Consistent with those reports, the present findings showed a significantly greater proportion of “Score 0” (no dye penetration) restorations in the composite group, supporting the inference that improved interfacial adaptation and adhesive sealing contributed to performance [5–7]. Conversely, conventional glass ionomer cement relies primarily on acid–base setting reactions and ionic bonding with tooth calcium. While this chemical adhesion and hydrophilicity can be advantageous in cervical lesions where isolation is difficult [2,3], ionomers are also more vulnerable to early moisture imbalance (syneresis/imbibition), surface dissolution, and maturation-related dimensional changes that may contribute to marginal breakdown under thermal stress [3,8]. Additionally, the cervical region is exposed to flexural forces and cyclic loading; when combined with thermal cycling, these factors can propagate interfacial defects and increase leakage susceptibility [3,6,8]. Evidence from earlier comparative investigations indicates that conventional ionomers may show higher dye penetration at gingival margins relative to resin-based materials, particularly after thermocycling [6,9]. The present study’s thermocycling protocol likely accentuated these differences by repeatedly challenging the tooth–restoration interface through expansion–contraction mismatch and water-mediated degradation [6,9]. Color stability outcomes also favored resin composite restorations. Discoloration in restorative materials is multifactorial, involving intrinsic factors (resin matrix composition, filler characteristics, polymer network density) and extrinsic factors (surface roughness, staining media adsorption, water sorption) [10–12]. Resin composites with modern filler systems and better polymer conversion frequently show lower ΔE shifts compared with ionomer-based materials, which are comparatively more porous and water-reactive [10,13]. The current findings—mean ΔE values remaining largely within clinically acceptable limits for composite, and markedly higher ΔE shifts for glass ionomer—align with reports that ionomer-based materials tend to exhibit greater staining and perceptible color change after aging or exposure to chromogenic solutions [10,13,14]. The interpretation of “clinical acceptability” for color change commonly uses ΔE thresholds in the range of ~3.3 as a pragmatic visibility/acceptability benchmark in dental materials research [11,15]. Using this conventional threshold, a substantially higher percentage of glass ionomer samples exceeded acceptable ΔE compared with composites, indicating that cervical restorations using conventional glass ionomer may be more prone to esthetic compromise over time, especially in patients with high staining exposure (tea/coffee, tobacco) [10–12]. From a practice standpoint, these results support selecting resin composite when esthetic longevity and marginal integrity are the primary priorities in Class V restorations—particularly in visible zones—while recognizing that glass ionomer may still be appropriate in high-caries-risk contexts or where fluoride release and simplified handling provide benefit [2,3]. In real-world clinical settings, restoration survival is strongly influenced by operator factors and moisture contamination; studies in general practice have highlighted that contamination and lesion characteristics can reduce longevity for cervical restorations and may differentially affect materials [3,16]. Therefore, the material choice should be individualized, balancing esthetic expectations, isolation feasibility, lesion depth, and caries risk. Finally, this study’s outcomes are directionally consistent with conservative dentistry perspectives emphasizing the role of the oral environment—particularly salivary factors—in influencing material behavior, surface interactions, and staining potential [17]. Complementary evidence on nanocomposite color behavior and practitioner preferences for Class V materials further contextualizes the present findings within applied restorative decision-making [18-20]. Limitations and Clinical Implications Limitations: 1. In-vitro conditions cannot fully replicate intraoral challenges such as cyclic occlusal loading, pH fluctuations, salivary enzymes, and long-term biofilm exposure. 2. Dye penetration is a useful comparative method but does not directly quantify clinical failure risk. 3. The evaluation did not include resin-modified glass ionomer or newer bioactive restorative options, which may perform differently. Clinical implications: 1. For cervical restorations in visible areas, resin composite is likely to provide superior esthetic stability and marginal sealing when placed under proper isolation and bonding protocols. 2. Conventional glass ionomer may require careful case selection and patient counseling regarding potential discoloration, particularly in high staining exposure. 3. When isolation is compromised or caries risk is high, fluoride-releasing materials may still be justified, but esthetic expectations should be managed.

Within the limitations of this in-vitro comparative evaluation, resin composite restorations demonstrated significantly better marginal integrity and superior color stability than conventional glass ionomer restorations in Class V cavities after thermocycling and staining. Composite resin may therefore be preferred for esthetically demanding cervical restorations where reliable bonding and isolation can be achieved.

1. Teixeira DNR, Thomas RZ, Soares PV, Cune MS, Gresnigt MMM, Slot DE. Prevalence of noncarious cervical lesions among adults: A systematic review. J Dent. 2020;95:103285. 2. dos Reis Perez C, Gonzalez MR, Prado NAS, de Miranda MS, Macêdo Mde A, Fernandes BM. Restoration of noncarious cervical lesions: when, why, and how. Int J Dent. 2012;2012:687058. 3. Stewardson DA, Creanor SL, Thornley P, Bigg T, Bromage C, Browne A, et al. The survival of Class V restorations in general dental practice. Br Dent J. 2012;212(6):E9. 4. Irie M, Suzuki K, Watts DC. Vertical and horizontal polymerization shrinkage in composite restorations: dimensional change and implications for marginal adaptation. Braz Oral Res. 2014;28(Spec No):1-8. 5. Umer F, Khan FR. An in vitro evaluation of microleakage in class V preparations restored with different restorative materials. J Conserv Dent. 2011;14(4):305-308. 6. Kaplan I, Goldberg J, Lasilla J, et al. Microleakage of composite resin and glass ionomer cement restorations in Class V cavities. J Prosthet Dent. 1992;67(3):616-623 7. Luong E, Shayegan A. Assessment of microleakage of class V restored by resin composites and glass ionomers using different conditioning methods: an in vitro study. Int J Dent. 2018;2018:1-7. 8. Venugopal K, Lakshmi T, Ramasamy P, et al. A comparative evaluation of microleakage between resin-based composites and glass ionomer-based restorations in Class V cavities: an in vitro study. J Pharm Bioallied Sci. 2021;13(Suppl 1):S448-S451. 9. Ahmed W, Majeed A, et al. Gingival microleakage of Class V composite restorations: influence of restorative techniques and materials. J Contemp Dent Pract. 2013;14(1):622-628 10. Sabatini C, Campillo M, Aref J. Color stability of ten resin-based restorative materials. J Esthet Restor Dent. 2012;24(3):185-199. 11. Vichi A, Ferrari M, Davidson CL. Color and opacity variations in three different resin-based composite products after water aging. Dent Mater. 2004;20(6):530-534. 12. Schulze KA, Marshall SJ, Gansky SA, Marshall GW. Color stability and hardness in dental composites after accelerated aging. Dent Mater. 2003;19(7):612-619. 13. Alacote-Mauricio B, et al. Color stability in a giomer, a conventional glass ionomer, and a resin composite after exposure to staining solutions. J Int Oral Health. 2023;15(4):357-366 14. Abuljadayel R, et al. Evaluation of bioactive restorative materials’ color stability after artificial aging and thermocycling in staining solutions. Materials (Basel). 2023; 15(8):e43038 15. Sinha RR, Fidha M, Siddique S, Chiluvuri P, Pandey PRP, Mahajan A, Syed AK. Preference of restorative material for class V restoration among BDS students, interns, practising dentists and post graduate students: a cross sectional survey. J Cardiovasc Dis Res. 2021;12(6):1652-1656. 16. Devi Priya B, Syed AK, Danda OEB, Dasarathi A. Root end filling material which is better in marginal adaptation? An invitro study. Int J Med Biomed Stud. 2021;5(1):112-128. 17. Shetty G, Tiwari RVC, Tiwari HD, Dutta P, Jaiswal A, Syed AK. Role of saliva in conservative dentistry. Int J Early Child Spec Educ. 2022;14(1):3697-3703. 18. Arora M, Penumudi SM, Akula T, Chaitanya M, Ram S, Yaragani A, Syed AK. Assessment of the color variation of the various nanocomposites: an invitro study. Int J Med Biomed Stud. 2022;6(4):103-108. 19. Patyal A, Rathore BS, Tiwari RVC, Varma PK, Syed AK, Tiwari HD, Mahajan A. Comparative evaluation of root resorption associated with maxillary canine in OPG versus CBCT: an original research. JCDR. 2022;13(4):782-786. 20. Shaik I, Dasari B, Alapati S, Dhavala PC, Tiwari R, Tiwari HD. Effect of sterilization and irrigating solutions on nanostructure alteration of Ni-Ti rotary instruments in endodontics: an atomic force microscopic study. J Pharm Bioallied Sci. 2024;16(Suppl 1):S613-S618.