DOI: 10.31038/IJNM.2026713

Abstract

Background: Non-carious cervical lesions (NCCLs) pose a restorative challenge due to their multifactorial etiology, absence of enamel margins, and high stress concentration at the cervical region, which predisposes restorations to marginal breakdown and debonding. Nanofilled composites and resin-modified glass ionomer cements (RMGIC) are widely used for restoring NCCLs, offering distinct advantages in esthetics, mechanical strength, and adhesion, respectively. However, their comparative clinical performance remains debated. This split-mouth trial evaluated and compared nanofilled composite and RMGIC in Class V NCCLs using modified United States Public Health Service (USPHS) criteria

Materials and Methods: Thirty patients with 100 Class V NCCLs were enrolled, and lesions were randomly allocated to nanofilled composite (Filtek Z350 XT, 3M ESPE) or RMGIC (GC Gold Label LC 2), following standard adhesive protocols. Restorations were evaluated at baseline, 3 months, and 6 months for anatomic form, surface roughness, marginal adaptation, marginal discoloration, retention, fracture, secondary caries, and postoperative sensitivity using modified USPHS criteria. Data were analyzed using ANOVA (p < 0.05).

Results: All 100 restorations were available at 6 months. Both materials showed clinically acceptable performance across all parameters, with no significant differences in anatomic form (p=0.337), surface roughness (p=0.695), marginal adaptation, retention, fracture, secondary caries, or postoperative sensitivity (p=0.954). A significant difference was noted in marginal discoloration (p=0.031), with RMGIC showing progressive color mismatch, while nanofilled composite maintained superior color stability.

Conclusion: Both materials performed satisfactorily in NCCLs over 6 months, but nanofilled composite demonstrated superior esthetic stability, making
it preferable in esthetically demanding regions.

Keywords

Non-carious cervical lesions, Nanofilled composite, Resin-modified glass ionomer cement, USPHS criteria, Clinical evaluation, Marginal discoloration

Introduction

Non-carious cervical lesions (NCCLs) involve the irreversible loss of tooth structure at the cervical region, typically around the cementoenamel junction, in the absence of bacterial involvement, and their prevalence and clinical guidelines for restoration have been comprehensively reviewed in the literature [1]. Abrasion, erosion, and abfraction are considered the principal etiological factors, often acting synergistically to produce progressive cervical dentin exposure, which in turn is frequently associated with dentinal hypersensitivity requiring active clinical management [2]. Given the absence of enamel margins and the high stress concentration at the cervical region, restoration of NCCLs remains technically demanding, and no single restorative material has been established as clearly superior, with material selection continuing to be guided largely by clinician preference and lesion characteristics [1,3]. Among the restorative options available, glass ionomer cements (GICs) and composite resins remain the most extensively studied and compared. A systematic review and meta-analysis comparing GICs with composite resins in NCCL restorations found comparable clinical performance between the two material classes across parameters such as retention, marginal adaptation, and marginal discoloration, though considerable heterogeneity was noted across the included studies [3]. Resin-modified glass ionomer cement (RMGIC) was subsequently introduced to overcome the mechanical and esthetic limitations of conventional GIC while retaining its fluoride release and chemical adhesion to tooth structure; a retrospective evaluation of Class V restorations found substantially lower loss rates for RMGIC compared with conventional GIC, supporting its favorable long-term retention [4]. Randomized split-mouth trials directly comparing RMGIC with resin composite restorations in NCCLs have similarly reported acceptable short-term clinical performance for both materials, though postoperative sensitivity and marginal behavior have shown material-dependent differences [5,6]. Combined surgical-restorative approaches using RMGIC and nano-ionomer restorations alongside connective tissue grafting for NCCLs with associated gingival recession have also been explored, reflecting the broader clinical interest in optimizing both esthetic and periodontal outcomes at the cervical margin [7]. Building on this evidence base, the introduction of nanofilled composites, incorporating nanoscale filler particles, has further expanded the restorative options available for NCCLs, offering improved mechanical properties, wear resistance, and surface finish compared with earlier microfilled composite systems. More recent randomized split-mouth trials evaluating newer esthetic restorative systems, including surface pre-reacted glass-ionomer (S-PRG)–containing composites against nanotechnology-based composites, have generally found no statistically significant differences in overall clinical performance between materials over extended follow-up, underscoring that the comparative behavior of contemporary esthetic and ion-releasing materials in NCCLs remains an active area of investigation [8]. Despite this expanding body of evidence, direct split-mouth comparisons specifically between nanofilled composite and RMGIC using standardized clinical criteria over a defined follow-up period remain relatively limited. Given this continued need for material-specific comparative data, the present study was undertaken to clinically evaluate and compare the performance of nanofilled composite and RMGIC in Class V NCCLs using modified USPHS criteria over a 6-month follow-up period.

Study Design and Participants

This interventional, split-mouth clinical study was conducted in the Department of Conservative Dentistry and Endodontics, Government Dental College and Hospital, Nagpur. Ethical approval for the study protocol was obtained from the Institutional Ethics Committee of the same institution (IEC/GDCHN/29/2024). Written informed consent was obtained from all participants prior to their enrolment in the study. The sample size was calculated based on proportions reported in a previous study [10] for subjects presenting with at least two non-carious cervical lesions (NCCLs), using a significance level of α = 0.05 and a statistical power of 80%. With proportions of 0.077 and 0.154 for the two comparison groups, the minimum calculated sample size was 45 teeth per group. To compensate for potential loss to follow-up, the sample size was increased to 50 teeth per group, yielding a total of 100 restorations placed in 30 patients. Participants were selected based on predefined inclusion and exclusion criteria. Patients aged 18–55 years, presenting with at least two NCCLs that responded positively to vitality testing and demonstrated acceptable oral hygiene (Oral Hygiene Index–Simplified [OHI-S] score of 0.0–3.0), were included in the study. Patients were excluded if they presented with poor oral hygiene, active carious lesions, heavy bruxism, tooth fractures or cracks, or were currently undergoing orthodontic treatment. Additionally, patients who had undergone dental bleaching within the preceding six months or presented with lesions of abfractive origin were excluded from participation. A total of 100 NCCLs were diagnosed in 30 patients, each presenting with a minimum of two qualifying lesions, irrespective of the underlying etiology; lesion width and depth were not considered as selection criteria. The lesions were randomly allocated into two groups of 50 teeth each: Group I, restored with nanofilled composite (Filtek Z350 XT, 3M ESPE), and Group II, restored with resin-modified glass ionomer cement (RMGIC; GC Gold Label LC 2). A split-mouth design was employed, wherein a lesion in one quadrant was restored with nanofilled composite, while the corresponding contralateral lesion was restored with RMGIC, thereby minimizing inter-patient variability.

Restorative Procedure and Clinical Evaluation

Prior to restoration, all selected teeth were cleaned using a slurry of pumice and water. A 1-mm bevel was placed along the enamel margins using a high-speed diamond bur under continuous water coolant. Teeth were isolated using cotton rolls and gingival retraction cord to ensure adequate moisture control and prevent contamination. Following bevel preparation, the enamel and dentin surfaces were dried using oil-free air from the dental unit’s triple syringe. For lesions assigned to the nanofilled composite group, a universal bonding agent (Single Bond Universal, 3M ESPE) was applied according to the manufacturer’s instructions, involving active application with agitation for 20 seconds, followed by gentle air-thinning to achieve a uniform, even layer, and light-curing for 20 seconds using an LED curing unit (Bluephase). The nanofilled composite was then placed incrementally and light-cured. For lesions assigned to the RMGIC group, only bevel preparation was performed prior to material placement, in accordance with the manufacturer’s self-adhesive application protocol, without the use of a separate bonding agent. Following restoration, gross finishing was performed using yellow-coded flame- and football-shaped diamond finishing burs, followed by Shofu polishing discs. Final polishing was achieved using Shofu silicone polishers, including rubber cup-, flame-, and wheel-shaped tips, to obtain a smooth, high-luster surface finish. All restorations were clinically evaluated at 7 days (baseline), 3 months, and 6 months by two calibrated, blinded examiners using the modified United States Public Health Service (USPHS) criteria (Table 1). The parameters assessed included anatomic form, surface roughness, marginal adaptation, marginal discoloration, retention, fracture, secondary caries, and postoperative sensitivity. Data obtained at each follow-up interval were statistically analyzed using one-way analysis of variance (ANOVA), with the significance level set at p < 0.05.

Table 1: Categories and score descriptions for the clinical evaluation of restorations according to the modified USPHS criteria.

Category	Score	Criteria
Anatomic Form	0	Restoration is continuous with tooth anatomy.
	1	Slightly under- or over-contoured restoration.
	2	Restoration is under-contoured, dentin or base exposed.
	3	Restoration is missing or partially fractured; restoration causes pain in tooth/adjacent tissue.
Surface Roughness	0	Smooth surface.
	1	Slightly rough or pitted, can be polished.
	2	Rough, cannot be polished.
	3	Surface deeply pitted with irregular grooves.
Marginal Adaptation	0	Restoration is contiguous with tooth anatomy, explorer does not catch.
	1	Explorer catches, but no visible crevice into which explorer will penetrate.
	2	Crevice at margin, enamel exposed.
	3	Obvious crevice at margin, dentin or base exposed.
	4	Restoration mobile, fractured, or missing.
Marginal Discoloration	0	No discoloration evident.
	1	Slight staining, can be polished away.
	2	Obvious staining, cannot be polished away.
	3	Gross staining.
Retention	0	No loss of restorative material.
	1	Partial loss of restorative material.
	2	Missing restoration.
Secondary Caries	0	No evidence of caries contiguous with restoration margin.
	1	Caries evident contiguous with restoration margin.
Fracture	0	Absent.
	1	Small fracture, clinically acceptable.
	2	Clinically unacceptable fracture.

Statistical Analysis

Data were analyzed using the Statistical Package for the Social Sciences (SPSS, version XX; IBM Corp., Armonk, NY, USA). Descriptive statistics, expressed as mean ± standard deviation, were calculated for each clinical parameter at 7 days (baseline), 3 months, and 6 months. Between-material comparisons of nanofilled composite and resin-modified glass ionomer cement (RMGIC) were performed using one-way analysis of variance (ANOVA). A p-value of < 0.05 was considered statistically significant.

Result

All 100 restorations (100%) were available for evaluation at baseline, 3 months, and 6 months, with no loss to follow-up. Both restorative materials demonstrated clinically acceptable performance over the 6-month follow-up period, as assessed using the modified United States Public Health Service (USPHS) criteria. No statistically significant differences were observed between nanofilled composite and resin-modified glass ionomer cement (RMGIC) with respect to anatomic form (p = 0.337), surface roughness (p = 0.695), or postoperative sensitivity (p = 0.954). Neither material exhibited failures in retention, fracture resistance, marginal adaptation, or secondary caries during the study period. However, a statistically significant difference was observed in marginal discoloration (p = 0.031), with RMGIC restorations exhibiting progressive color mismatch, whereas nanofilled composite restorations demonstrated better color stability throughout the evaluation period. Overall, these findings indicate that although both materials exhibited satisfactory clinical performance over 6 months, nanofilled composite demonstrated superior esthetic stability compared with RMGIC (Table 2).

Table 2: Comparative evaluation of clinical performance of Nanofilled Composite and Resin-Modified Glass Ionomer Cement (RMGIC) at 7 days, 3 months, and 6 months based on USPHS criteria. Data are presented as mean ± standard deviation (SD). ANOVA * means significant. d- Days; m-Months.

Criteria	Nanofilled Composite (Mean ± SD)	RMGIC (Mean ± SD)	Between-Material p-value
Anatomic Form	7d: 0.06 ± 0.23 3m: 0.06 ± 0.23 6m: 0.06 ± 0.23	7d: 0.08 ± 0.24 3m: 0.07 ± 0.25 6m: 0.09 ± 0.26	0.337
Surface Roughness	7d: 0.07 ± 0.25 3m: 0.07 ± 0.25 6m: 0.07 ± 0.25	7d: 0.06 ± 0.22 3m: 0.07 ± 0.23 6m: 0.08 ± 0.27	0.695
Marginal Discolouration	7d: 0.12 ± 0.38 3m: 0.12 ± 0.38 6m: 0.12 ± 0.38	7d: 0.10 ± 0.35 3m: 0.14 ± 0.39 6m: 0.18 ± 0.42	0.031 *
Retention & Fracture	7d: 0.00 ± 0.00 3m: 0.00 ± 0.00 6m: 0.00 ± 0.00	7d: 0.00 ± 0.00 3m: 0.00 ± 0.00 6m: 0.00 ± 0.00	–
Marginal Adaptation & Secondary Caries	7d: 0.00 ± 0.00 3m: 0.00 ± 0.00 6m: 0.00 ± 0.00	7d: 0.00 ± 0.00 3m: 0.00 ± 0.00 6m: 0.00 ± 0.00	–
Post-operative Sensitivity	7d: 0.08 ± 0.27 3m: 0.08 ± 0.27 6m: 0.00 ± 0.00	7d: 0.07 ± 0.25 3m: 0.05 ± 0.22 6m: 0.02 ± 0.15	0.954

Discussion

Non-carious cervical lesions (NCCLs) are frequently encountered in clinical practice and pose considerable challenges in restorative management [9]. Research evaluating Class V restorations placed in cervical root caries lesions has reported substantially higher failure rates, with cumulative failure rates after two years in university clinical settings ranging from approximately 27% to 96% [11]. Aesthetic materials commonly used for Class V restorations can be broadly classified into resin composites, conventional glass ionomer cements (GICs), resin-modified glass ionomer cements (RMGICs), and compomers. Among these materials, RMGICs have demonstrated favorable clinical performance owing to their ability to chemically adhere to tooth structure and their relatively low elastic modulus, which may help accommodate tensile stresses in the cervical region associated with functional loading and occlusal discrepancies. Furthermore, their coefficient of thermal expansion closely approximates that of natural tooth structure, potentially contributing to restoration durability, particularly at enamel margins in NCCLs [12]. Long-term clinical evaluations of conventional composite restorations placed directly or indirectly in high-stress regions indicate that restoration fracture is among the common modes of failure. Although composite restorations can survive for more than 10 years, their longevity may be lower than that of GIC restorations in certain clinical settings, prompting continued improvements in composite formulations, from microfilled materials to nanofilled composites [13]. Microfilled composites used in NCCLs provide satisfactory aesthetics and a smooth surface finish; however, long-term evaluations have reported lower retention and greater marginal degradation than those observed with microhybrid or nanofilled composites. Although their greater flexibility was initially considered advantageous in stress-prone cervical regions, clinical findings suggest that reduced stiffness does not necessarily improve retention, and microfilled composites may exhibit inferior long-term durability [14]. Against this background, the present study aimed to compare the clinical performance of nanofilled composite and RMGIC in Class V NCCLs using a split-mouth design. This design minimizes interindividual variability by enabling direct intra-individual comparisons of restorative materials, thereby strengthening the validity of treatment effect estimates in clinical evaluations of NCCLs [15]. The findings of the present study demonstrated that both nanofilled composite and RMGIC provided clinically acceptable performance over the 6-month follow-up period. However, nanofilled composite demonstrated significantly better marginal color stability than RMGIC, with the latter exhibiting progressive marginal discoloration. These findings suggest that nanofilled composite may be preferable when aesthetic outcomes are a primary consideration. The results are consistent with those reported by Kaur et al. (2015) [16], who found that nanofilled composites exhibited greater resistance to erosive and abrasive challenges than microfilled composites and RMGIC. This evidence supports the potential advantages of nanofilled composites in maintaining surface stability and esthetic durability in cervical restorations.

In the oral environment, restorative materials are subjected to cyclic cervical stresses during occlusal loading, which may contribute to fatigue-related cracking and abfraction-associated wear. They are also exposed to abrasive and erosive challenges that can accelerate surface degradation. In addition to wear and surface deterioration, postoperative sensitivity is another important clinical concern associated with NCCL restorations and may cause considerable discomfort for patients [17,18]. Advances in adhesive dentistry, including the development of self-etch adhesives and selective enamel-etching techniques, have improved restorative outcomes by facilitating effective bonding and reducing the risk of postoperative sensitivity. Over time, postoperative discomfort may also diminish through natural pulpal responses, including tertiary dentin formation. Furthermore, modifications to conventional GICs to produce RMGICs, advances in composite formulations, and reductions in filler particle size have contributed to improvements in wear resistance, surface characteristics, and the potential to minimize postoperative sensitivity [19]. A systematic review and meta-analysis by Arbildo-Vega et al. (2025) [19] compared the clinical performance of GICs and composite resins in NCCL restorations. Based on 18 randomized controlled trials, the authors reported no statistically significant differences between the two material groups across the evaluated clinical parameters. These findings support the clinical acceptability of both restorative approaches, suggesting that material selection may depend on the clinical situation, handling characteristics, and aesthetic requirements. Adhesion in NCCLs remains challenging because of limited enamel availability, polymerization shrinkage stress, and functional stresses, which may contribute to marginal gaps and discoloration. Advances in adhesive systems and polishing techniques may help minimize these complications, while adequate oral hygiene is essential for reducing the risk of secondary caries and maintaining periodontal health [20]. A 36-month split-mouth randomized clinical trial by Vural et al. [21] compared microhybrid resin composites with RMGIC in cervical caries lesions. Both materials demonstrated high retention and acceptable marginal adaptation, with no statistically significant differences in overall clinical performance, although RMGIC exhibited

Conclusion

Within the limitations of the present study, both nanofilled composite and resin-modified glass ionomer cement (RMGIC) demonstrated clinically acceptable performance in non-carious cervical lesion restorations over the 6-month follow-up period. Although no statistically significant differences were observed between the materials for most of the evaluated clinical criteria, nanofilled composite exhibited superior marginal color stability. Therefore, nanofilled composite may be preferred when aesthetic outcomes are a primary consideration. Further studies with larger sample sizes and longer follow-up periods are warranted to confirm these findings and evaluate the long-term clinical performance of both restorative materials.

Conflict of Interest

The authors declare no conflict of interest.

Institutional Review Board Statement

Approved by the Institutional Ethics Committee

Author Contributions

Declared

Funding

This research received no external funding.

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