A One-Year Comparative Evaluation of Clinical Performance of Activa™ Bioactive composites with Microhybrid Composite In Abfraction Lesions: A Randomized Control Study

Introduction

Abfraction (AF) is a stress-induced non-carious cervical lesion [NCCL] caused by biomechanical loading forces on the teeth which has added more perplexity rather than resolving the dilemma of NCCL.¹ Clinical studies have revealed a greater percentage of restoration failures in the cervical area due to constant destruction of hard tissues of the tooth caused by parafunctional habits. NCCLs exhibit an increased amount of sclerotic dentin resulting in reduced bonding efficacy.²

Restoration of AFL is essential to alleviate hyper sensitivity, to prevent additional tooth structure loss, and to improve esthetics.

Various dental materials have been used for restoring AFL, such as composite resins, polyacid-modified resin composites (compomers), glass ionomer cements, and resin-modified glass-ionomer cements. Among these, composites exhibiting advanced esthetic and functional properties are preferred to preserve healthy tooth structure. Prior to restoration, occlusal adjustment is important for successful treatment.³

Microhybrid composites demonstrate superior elasticity and polish ability, minimum shrinkage stress, and lower modulus of elasticity (MOE).² This material has been commonly used in NCCLs restorations due to its low MOE which can flex the tooth under stress without compromising retention of the restoration.⁴ However, these composites exhibit higher marginal staining^4,5 and body discoloration⁶ over a period requiring a ceaseless search for the more suitable restorative material.

Activa™ (Pulpdent, USA), a recently introduced substance, comprises a proprietary bioactive ionic resin, a patented rubberized resin, and bioactive ionomer glass. This formulation replicates the chemical and physical characteristics of healthy teeth, while also offering the combined strength and aesthetics akin to composites. Additionally, it incorporates the advantageous attributes of glass ionomers.⁷ Hence, the aim of the study was to perform a comparative evaluation of the clinical performance of Activa™ bioactive composites with microhybrid composites in AFL for 1 year.

The null hypothesis posited that there would be no discernible distinction in the clinical performance of Activa™ bioactive and microhybrid in AFL (presumably a study or experiment) after the duration of one year.

Materials and Methods

Selected patients were informed about the protocol of this study and a written informed consent was obtained. They were allotted to 2 groups using computer-generated randomization. The study has been reviewed and approved by the Institutional Ethics Committee [IEC NO- KIDS/IEC/NOV-19/19] and has been registered under CTRI [REF/2020/04/032815]

Group distribution:

The sample size was determined by 2 tailed test with an α level of 5%, the minimum sample size was set at 28. To compensate for the dropout, an additional 3 samples (20%) were included per group, so the final sample size was n= 34 and 17 per group

GROUP 1 [control]: n= 17, Filtek Z250 microhybrid composite

GROUP 2 [experimental]: n=17, Activa™ bioactive composite

Patients having isolated AFL with more than 1 mm depth and not reaching the inner 1/3 of the dentin on the vestibular side, involving premolars and molars, caused due to abnormal biomechanical loading forces were selected. Patients with severe occlusal disturbances, parafunctional habits, TMJ disorders, cervical caries, and severe or chronic periodontitis were excluded from the study.

First, occlusal contacts were evaluated. They underwent occlusal correction through complete occlusal adjustment via selective grinding prior to restoration.

Methods for recording occlusal contacts:

The patients were asked to sit upright with the Frankfurt plane almost horizontal. Occlusal contacts were measured between 9 am and 11 am to rule out diurnal variation errors.

The shim stock (12 µm thick; Arti-Fol metallic film, Dr Jean Bausch, Germany) was placed on the occlusal surface of the right side of the jaw and the patient was guided to the close the mandible to the maximum intercuspation. Later, the patient was asked to perform a habitual gliding movement to the right in light contact at 0.5, 1, 2, and 3mm positions, while a constant pulling force was maintained on the shim stock. The non-working side contacts were examined when the shim stock was placed on the occlusal surface of the mandibular posterior teeth on the left side and the patient was asked to move the mandible toward the right side at 0.5, 1, 2, and 3mm positions. After the movement, the occlusal contact patterns were examined, and occlusal corrections were carried out.

Similar procedure was carried out on the left side to record the occlusal contacts of the patient.⁸

After occlusal adjustments were done, the same researcher performed all restorative procedures for standardization purposes. All restorations were carried out with rubber dam isolation and cleansing the tooth walls with pumice paste and water. Margins of AFL were beveled with a fine bur to reduce internal stress. The materials were handled and inserted according to the manufacturer’s recommendations.

Restorative procedure:

1. For Microhybrid Composite: [Filtek Z250]

Cavities were acid-etched with 37% phosphoric acid for 15 seconds and flushed out for 1 minute. Later, two layers of 3M Single Bond Bonding agent were placed, dispersed, dried for 5 seconds, and light-cured for 15 seconds. Then the composite was applied in successive layers inside the cavity and light-cured (1200 mw/cm² ) for 20 seconds.

2. For Activa™ Bioactive Composite [Pulpdent, USA]

In a similar fashion, etching and bonding were carried out following which the tooth was bulk filled with Activa™ using an automated syringe. It was then allowed to selfcure for 2 min, followed by light cure for 20 seconds using a LED light-curing unit set at 1200 mw/cm² . All these restorations were finally finished and polished using Super snap kit (Shofu, Japan).

Clinical evaluation- data collection

Two blinded examiners evaluated the restorations with a mouth mirror and probe at baseline, 1 month, 6 months, and 1 year by modified USPHS criteria by filling out an individual evaluation form for each patient. Modified USPHS criteria contained following parameters-Retention, Color Match, Marginal Discoloration, Marginal Adaptation, Secondary Caries, Surface Texture, Anatomic Form, Postoperative Sensitivity.⁹

Statistical analysis

The following non-parametric tests: Friedman’s ANOVA, the Wilcoxon post-hoc test, and the Mann-Whitney test were used. Each test was performed using SPSS VERSION 17 with a 5% level of statistical significance. To confirm the calibration of the evaluators, Kappa Cohen test was used and the results obtained were satisfactory. Both examiners were in agreement with each other

Results

The recall and retention rate were 100% throughout the evaluation period. A total of 34 restorations were evaluated at baseline, 1 month, 6 months, and 1 year recall.

Table 1 summarizes the statistical evaluation of clinical performance between Filtek and Activa groups at different time intervals. Table 2 shows intragroup analysis between Filtek and Activa at baseline, 6 months, and 1 year, respectively. In Intergroup analysis, all restorations gave 100% alpha ratings for all parameters until 1-month recall. However, in Filtek group, alpha ratings for color match, marginal discoloration, marginal adaptation, and anatomic form decreased at the end of 6 months. But this reduction did not show any statistical differences. Marginal staining was observed in Filtek group only.

Additionally, in Active discrepancies were observed in marginal adaptation and surface roughness at 6 months, although it was statistically insignificant (p>0.05).

At 1 year, all these criteria showed the same trend in both groups, but significant differences were not observed. Additionally, in microhybrid discrepancies in surface roughness were noticed and one patient experienced postoperative sensitivity at half-year interval which continued to be present at 1 year.

In intragroup assessment between baseline and 6 months, both groups yielded similar clinical behavior whereas at 1 year statistically significant difference (p=0.046) was noted with marginal adaptation criteria in the filtek group (Table 2).

Overall, all the restorations were clinically acceptable and both experimental groups showed statistically no significant differences (p>0.05) throughout the evaluation period.

Discussion

Abfraction lesions have challenged modern dentistry because of its multifactorial etiology, pathogenesis, diagnosis, and selection of different restorative procedures. Thus, creating a great deal of debate.¹

The crucial elements that influence the retention of cervical restorations are occlusion; degree of dentinal sclerosis; and the patient’s age. Material with a low MOE should be used to enhance the retention rate of cervical restorations. These materials can serve as a cushion because they are flexible enough to resist the polymerization stresses and help in dissipation of these stresses.⁶ The MOE of dentin is between 12 and 20 GPa. In the current study, filtek [9.53GPa]¹⁰ and Activa [4.8GPa]¹¹ with low MOE were chosen.

The universal adhesive used in the current study contains MDP monomer, which is highly resistant to hydrolysis. Good clinical behavior may be associated with micromechanical locking, chemical bonding of the poly alkenoic acid copolymer, and 10-MDP monomer with HAP.¹²

AFL more than 1 mm depth was considered as AFL <1 mm in depth requiring only monitoring at regular intervals.² At 1 year recall, 100% retention rates were noted unlike Tuncer who reported 91.8% of retention rates for microhybrid at 1 year recall in his study. He attributed this loss for not beveling the cavity margins.¹³ In this study, none of the restorations had popped out which could be associated to occlusal adjustment, beveling of cavity margins and selection of low MOE composites.

Wood stated that reducing excursive occlusal loads on a tooth in a lateral excursion would lead to a reduction in the rate of progression of abfraction lesions.¹⁴ In the current study, Metallic shimstock films made of metallic polyester film of 12 microns thick were used. The metallic film and its color variation offer an additional advantage of high spot precision over conventional shimstock films.¹⁵ Anderson et al. conducted a comparison between the use of an articulating paper technique and a shim stock method. They determined that the shim stock approach exhibited greater reliability in assessing dentists’ ability to evaluate occlusal contacts in the intercuspal position.¹

Microhybrid composites have been extensively studied in the restoration of NCCLs. They possess better mechanical and functional properties with improved esthetics. The present study is in accordance with a study done by Tuncer who concluded that two different microhybrid composites [TPH Spectrum and Z250] exhibited similar and sustainable clinical performance in AFL after 24 months recall.¹⁶

Loguercio et al., reported Filtek Z250 showed a tendency to body discoloration at 24 months recall period.⁶ Baracco reported that teeth restored with Adper Scotchbond SE + Filtek Z250 showed higher marginal discoloration over 2 years of evaluation.⁴ In accordance, the present study reported marginal discoloration in filtek group which was not statistically significant and needs long term evaluation.

Activa is the foremost bioactive composite with unique features and mechanical properties having shock-absorbing rubberized resin, ionomer, glass matrix, and bioactive fillers.⁷ It is claimed to have good bonding to the dentin without application of etchant and bonding agents. But the total etch technique was performed to increase the bond strength to dentin in the cervical region, which is in accordance to an invitro study done by Yadav et al.¹⁷ who evaluated microleakage in class V lesions restored with Activa and nanohybrid and found that Activa in combination with total etch adhesive (Tetric N Bond) showed the least microleakage. The present study is in positive correlation with the study done by Nassar who evaluated Class V cavities restored by different bioactive restorative materials - Activa™, Beautifil II, and Fuji IX GP for 1 year and found clinically acceptable behavior.¹⁸

At the conclusion of one year, no statistically significant distinctions were observed in the clinical performance between Activa and microhybrid. So, the null hypothesis was accepted. This is the first clinical study to use Active bioactive composite for NCCLs restorations.

The limitation could be the shorter study duration. Further long-term follow-ups with a large sample size should be considered for a broader understanding of the biomechanics of AFL, keeping in mind the challenges in diagnosing and impeding the progression of these lesions by relieving the occlusal stresses for a higher survival rate of restorations.

Conclusion

Considering the study’s inherent constraints, it can be inferred that both materials demonstrated satisfactory clinical performance after the completion of one year. However, discrepancies were noted in the marginal adaptation criteria for microhybrid. Active composites could be considered as the material of choice for restoring AFL. In addition, performing occlusal adjustments could enhance the survival rate of restorations by reducing the occlusal stress.

Declaration of Patient

The authors have obtained all appropriate consent forms.

Financial Support and Sponsorship

Nil.

Conflict of Interest

The manuscript was presented and secured the best paper award in the 22nd IACDE national PG convention held on 25th to 27th March 2022 at GSL Dental College.

Acknowledgments

Nil