One-year comparative evaluation of Ketac Nano with resin-modified glass ionomer cement and Giomer in noncarious cervical lesions: A randomized clinical trial.

AIM: The purpose of this study was to evaluate the clinical performance of Ketac Nano (Ketac™ N100), RMGIC (Fuji Filling™ LC), and Giomer (Beautifil® II) in noncarious cervical lesions (NCCLs).
MATERIALS AND METHODS: One operator restored 120 NCCLs in 20 subjects, with at least two lesions restored with one of the restorative materials: RMGIC (control group), Giomer and Ketac Nano (experimental groups). Two observers evaluated retention, marginal discoloration, marginal adaptation, color match, surface roughness, and postoperative sensitivity using modified USPHS criteria at baseline, 6, and 12 months. STUDY
DESIGN: Double-blinded randomized clinical trial (RCT). STATISTICAL ANALYSIS: Kruskal-Wallis test, Mann-Whitney U-test, Wilcoxon matched-pairs test.
RESULTS: There was statistically significant difference observed between Giomer, Ketac Nano and RMGIC after 12 months (P < 0.05). There was a significant decrease in retention rates for Giomer (P = 0.0050), increased marginal discoloration and color mismatch for Ketac Nano (P = 0.0025, P = 0.0053), increased surface roughness and color mismatch with RMGIC (P = 0.0022, P = 0.0077) from baseline to 12 months.
CONCLUSION: Within the limitations of this RCT of 12 months, Ketac Nano and RMGIC restorations were better retained in NCCLs while superior color match and surface finish were observed with Giomer restorations.

INTRODUCTION

Noncarious cervical lesions (NCCLs) occur at the neck of the tooth having multifaceted etiology, but not caused by dental caries, which manifests as abrasion, erosion, and abfraction.[12] Levitch et al. have suggested NCCLs need to be restored to prevent hypersensitivity, loss of tooth structure and pulpal exposure, enhance esthetics, and for the placement of partial denture design.[3]

Challenges encountered by the clinician during the restoration of NCCLs include dentinal sclerosis,[4] concentrated occlusal loading leading to cuspal flexure,[5] lack of mechanical retention, difficulty in moisture control and isolation, along with shape and location of these lesions.[2] Therefore, selection of restorative material is a critical factor in determining the clinical success.[26] Several materials and techniques have been tried to obtain the best performance in NCCLs,[6] among which most commonly used restorative materials are glass ionomers cements (GIC), RMGIC, and resin composites (RCs) and their combinations.[256]

Fuji Filling™ LC is a dual cure RMGIC, available in paste/paste system which helps in better handling characteristics compared to powder/liquid form.[7] RMGICs possess an improved mechanical strength, low moisture sensitivity, and improved clinical performance when compared to conventional GIC.[78] Brackett et al. have reported no significant difference in overall clinical performance of RMGIC when compared to RC in NCCLs after 2 years follow-up.[9] Vaid et al. after 1-year follow-up observed no significant difference between performance of RMGIC, Equia, and Nano Hybrid RC in NCCLs.[10]

Beautiful® II belongs to the second generations Giomer which uses surface-prereacted glass technology. Giomers are developed by combining the properties of RC along with high fluoride release and rechargeability of GIC.[1112] Jyothi et al.[12] observed no significant difference in the clinical behavior of Giomer and RMGIC in NCCLs after 1-year follow-up.

Ketac™ N100 is new light cured Nano-Filled RMGIC, which is supplied in user-friendly nonrinsing, paste/paste dispensing system. It has silane-treated glass, silica, zirconia, and ceramic nano fillers. Manufacturer claims increased mechanical properties, wear resistance, and high polish retention.[13] Perdigao et al. after 1-year recall observed a significant difference between RMGIC, Nano-Filled RMGIC, and RC IN NCCLs.[8]

The available literature does not show any studies comparing the clinical performance of RMGIC (Fuji Filling™ LC), Ketac Nano (Ketac™ N100), and Giomer (Beautifil® II) in NCCLs. Hence, the purpose of the present study is to compare and evaluate the clinical performance of Ketac Nano with RMGIC and Giomer. The null hypothesis was there is no difference in the clinical performance of these three restorative materials in NCCLs after 1-year follow-up.

MATERIALS AND METHODS

This clinical trial followed the Consolidated Standards of Reporting Trials statement[14] and was conducted after obtaining the Institutional Ethical Committee clearance. Written informed consent was obtained from twenty participants aging 35–65 years requiring treatment for NCCLs [Figure 1]. Participants having three pairs of wedge-shaped NCCLs on premolars with depth of 1-3 mm and 2°, 3°, or 4° dentinal sclerosis,[15] good gingival/periodontal health, and occlusion/proximal contact were included in the study. Participants having rampant caries, parafunctional habits, and who were unable to return for recall evaluations were excluded from the study. The minimum sample size required is 75, i.e., 25 for each group with a 95% confidence interval. Anticipating the loss of patients in recall follow-up, a total of 120 NCCLs in twenty patients were randomly assigned into three groups of forty each following a split mouth design. In this design, patient with six premolars (maxillary/mandibular) were selected, which were paired into three groups. Each study material was randomly assigned to the right and left premolar to form a pair in the group. Randomization and allocation concealment was done by faculty member not involved in any phase of the study. Particulars of the allocated groups were entered on cards sequentially numbered, opaque, and sealed envelopes.

Figure 1

Flow chart. nP: Number of patients, nR: Number of restorations

Restorative procedure

One operator who was not involved in the evaluation performed all the restorative procedures. After oral prophylaxis and color matching, the NCCLs were cleansed with pumice slurry. Following the American Dental Association guidelines,[16] no additional retentive features were performed. Isolation was performed with cotton rolls, saliva ejector, and gingival retraction cords. Teeth in RMGIC Group were conditioned with Self Conditioner (GC Corp., Tokyo, Japan) and restored with Fuji Filling™ LC (GC Corp., Tokyo, Japan) which was taken as control group. Teeth in Ketac Nano Group were surface pretreated with Primer (Ketac™ N100 Nano Ionmer Primer [3M ESPE, St. Paul, MN USA]) and restored with the Ketac™ N100 (3M ESPE, St. Paul, MN, USA). Teeth in GIOMER Group followed a two-step self-etch protocol with FL Bond II LC (Shofu, Kyoto, Japan) and restored with Beautifil® II (Shofu, Kyoto, Japan). Restorations were cured with a light-emitting diode curing unit (Bluephase, Ivoclar Vivadent, Schaan, Liechtenstein) with an intensity of 1200 mV/cm2 for 20s. Extra-fine diamond points and Sof-Lex™ disks (3M ESPE, St. Paul, MN, USA) were used for immediate finishing and polishing. All the subjects were instructed to brush with ultra-soft toothbrush, toothpaste, and educated to perform a good brushing technique.

Clinical evaluation

Two observers who were blinded about restorative procedures evaluated the restorations at baseline (immediately), 6, 12 months using modified USPHS[16] criteria (Alpha, Bravo, Charlie scores) for retention, color match, marginal staining, marginal adaptation, surface texture, and postoperative sensitivity. In case, there was no consensus; a third observer evaluated the restoration.

The clinical parameters at 0, 6, and 12 months were analyzed using Kruskal–Wallis test. Comparison between different groups at recall visits was done using Mann–Whitney U-test. Comparison of clinical parameters at periodic time intervals for each individual groups analyzed using Wilcoxon matched-pair test. Inter-examiner agreement was done using Kappa Cohen analysis. The data were statistically analyzed through SPSS 18.0 version (SPSS Inc, Chicago, USA). P < 0.05 was established to state the statistically significant difference.

RESULTS

All the twenty subjects were available for baseline, 6, 12 months recall appointments, and 120 restorations were evaluated. Baseline demographic and clinical characteristics of NCCLs for each group were given in Table 1. In the present study, interexaminer agreement was observed to be 95%. 42 teeth showed mild preoperative sensitivity. Postoperative sensitivity was not observed for any of the restorations. Table 2 shows the comparative clinical data at recall follow-up for the parameters observed in the study.

Table 1

Baseline demographic and clinical characteristics of noncarious cervical lesions in each group

Table 2

Comparison of resin-modified glass ionomer cement, Ketac Nano, Giomer at each interval for retention, color match, surface roughness, marginal adaptation, and discoloration

Table 3a shows a significant reduction in alpha scores for clinical parameters such as surface roughness and color match in RMGIC, retention in Giomer, marginal discoloration, and color match for Ketac Nano restorartions from baseline to 12 months recall with P < 0.05.

Table 3a

Comparison of tested restorative materials that scored alpha from baseline to 12 Months using Kruskal-Wallis test

Tables 3b and 3c shows pair-wise comparison between tested restorative materials at 6 and 12 months, respectively. Significant difference observed for clinical parameters such as retention, marginal discoloration, surface roughness, and color match with P < 0.05.

Table 3b

Pair-wise comparison between tested restorative materials that scored alpha at 6 months using Mann-Whitney U-test

Table 3c

Pair-wise comparison between tested restorative materials that scored alpha 12 months using Mann-Whitney U-test

DISCUSSION

This study evaluated the clinical performance of RMGIC, Ketac Nano, and Giomer using modified USPHS criteria similar to other studies.[8121718] According to Krithikadatta patient-related factors can be eliminated by following a balanced study design.[16] Hence, in the current randomized clinical trial (RCT), a paired tooth and split mouth design on maxillary and mandibular premolars were applied during randomization. According to Aw et al., the incidence of dentin sclerosis in NCCLs[19] was found to be 76%, thus making it one of the most common characteristic features of NCCLs.[2] Hence, in the present study, dentinal sclerosis variable was kept constant by excluding nonsclerotic lesions, similar to other clinical studies.[815]

Retention of restorations in NCCLs is mainly through bonding to tooth structure.[16] Adhesion of Ketac Nano is through chemical bonding with hydroxyapatite in tooth structure.[13] Coutinho et al. in transmission electron microscope (TEM) analysis revealed formation of a tight junction with dentin without signs of dentin demineralization or hybrid layer formation.[10] Adhesion of RMGIC occurs through a combination of chemical and micromechanical bonding.[278] Bond strength values of RMGIC[10] to dentin ranges from 13.56 to 19.67 MPa, Ketac Nano[13] to dentin ranges from 12.6 ± 6.5 MPa, and FL Bond II[20] to nonetched dentin ranges from 37.7 ± 3.2 MPa. Despite of higher bond strength values of FL Bond II to nonetched dentin, loss of eight restorations was observed indicating a bond failure with Giomer restorations. The results of the present study were in contrary to clinical studies.[1112] This difference may be due to the presence of sclerosed dentin in NCCLs of the current study. Restorative materials with low elastic modulus are intended to flex with the tooth and better resist the cervical flexure in NCCLs without debonding.[1221] Ketac Nano[21] and RMGIC[12] have low elastic modulus when compared to Giomer.[11] This could be another reason for the failure of Giomer restorations in the present study.

In the present study, marginal discoloration was observed to be high with Ketac Nano, which was similar to other clinical research.[817] Versluis et al.[22] have reported that Ketac Nano undergoes rapid hygroscopic expansion to compensate polymerization shrinkage after 1 week and continued till 1 year.[8] Hence, these irregular margins might lead to pigment absorption, plaque accumulation on restorations rather than marginal breakdown.[817]

In current RCT, good marginal adaptation was observed in Ketac Nano which was not significant with RMGIC and Giomer. Similarly, Ketac Nano showed least microleakage under in vitro conditions conducted by Abd et al.[23] and Hussein et al.[24] In a three dimensional finite element analysis conducted by Srirekha et al. observed least stresses in Ketac Nano group.[21] In contrary, Perdigao et al. observed significant increase in Bravo scores regarding marginal adaptation in Ketac Nano after 1 year.[8]

Smooth surface with high gloss retention was observed for Giomer restorations in all the recall evaluations, resembling its typical nature to RC. The results of the present study were in corroboration with the previous studies.[1112] In this RCT, Ketac Nano showed high polish retention than RMGIC due to the presence of silane-treated nano-sized fillers particles[25] (0.1–100 nm) which leads to good filler and matrix adhesion. In an in vitro study, Hussein et al. under atomic force microscope observed that Ketac Nano showed minimum erosion with least roughness test values among other glass ionomer materials used in the study.[24] Similar to the previous clinical research, RMGIC showed high surface roughness.[82627] This could be due to the larger and irregular filler particle size of RMGIC (3–4 μ).[112627]

Color mismatch of RMGIC and Ketac Nano restorations observed in the present study was similar to other clinical research.[8] Unlike Giomer, RMGIC and Ketac Nano need mixing procedure before placement which introduces porosity leaving behind rough surface, plaque accumulation, and staining.[11]

Even though 1 year evaluation is short period, it gives valuable initial data regarding the clinical behavior of restorative materials. Current RCT showed 100% retention rates in RMGIC and Ketac Nano while 100% color match and surface finish was observed with Giomer. Tay and Pashley in a TEM analysis observed uneven etching, hybridized intermicrobial matrix, and partially dissolved hypermineralized layer along with areas devoid of hybrid layer when employing mild self-etch primers (SEPs) in sclerotic dentin.[4] Similarly, in the RCT, FL Bond II which is a mild SEP showed reduced retention rate of 17.5% after 12 months.

Limitations of the present study include short follow-up period and cluster effect caused due to placement of more than four restorations. Hence, further clinical studies should be aimed at incorporating longer follow-up periods and by avoiding cluster effect.

CONCLUSION

Within the limitations of this RCT of 12 months follow-up following conclusions can be drawn:

High retention rates were seen with RMGIC and Ketac Nano when compared to Giomer, which were statistically significant

Marginal discoloration was found to be high for Ketac Nano which was statistically significant with Giomer and RMGIC

Surface roughness and color mismatch was statistically high for RMGIC

Giomer showed statistically significant difference in surface finish with RMGIC and color match with RMGIC and Ketac Nano.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.