Clinical Performance of a Bioactive Restorative Material vs a Glass Hybrid Restorative in Posterior Restorations in High-risk Caries Patients

INTRODUCTION

As one of the most commonly used restorative materials, resin composites have been widely used for about 50 years. Resin composites are now considered the first choice as restorative material due to their esthetics and direct-filling properties.¹ About 200 million resin composite dental restorations are placed per year in the United States, of which half failed within 10 years.² Obviously, there is a need for improvement to decrease the failure rates and enh ance longevity. The long-term durability of resin composites faces challenges due to failures caused by secondary caries and bulk fractures. More strategies in the development of self-repairing, antibacterial, and bioactive materials enhancing tissue regeneration, will provide new approaches to improve composite restorations.¹

While glass ionomers are not superior in esthetics, there are certain clinical situations where they are the material of choice for restoring teeth. The unique chemistry of glass ionomer allows for the release of fluoride at the margins of restorations and can have fluoride inside its chemical matrix recharged by exposure to other fluoride-releasing materials, thus offering important clinical advantages for patients at risk of caries or with caries lesions.³

However, conventional glass ionomer cement is more liable to wear than resin composite and has low physical-mechanical properties, while in addition, they are slow self-setting. Furthermore, they have poorer esthetics compared to resin composites.⁴ Resin-modified glass ionomers (RMGI) have improved physical-mechanical properties, such as being moisture contamination resistant at the early stages, decreased microleakage, and enhanced adhesion to the tooth structure, in addition to significant enhancement in esthetic properties when compared to conventional GICs.⁴ While in recent years, RMGI as a direct restorative material has become more user-friendly, most are not recommended for definitive restorations in permanent teeth in stress-bearing areas because they do not have the physical and mechanical properties of amalgam or resin composite.⁵

ACTIVA BioACTIVE RESTORATIVE (Pulpdent Corporation, Watertown, MA, USA) has recently been introduced with claims to be the first bioactive dental material with an ionic resin matrix, a shock-absorbing resin component, and bioactive fillers that mimic the chemical and physical properties of natural teeth. It is durable, wear and fracture-resistant, and chemically bonds to teeth, seals against bacterial microleakage, and releases and recharges with calcium, phosphate, and more fluoride ions than glass ionomers.⁴

EQUIA Forte Fil (GC Corporation, Tokyo, Japan) is a bulk-fill fluoride-releasing restorative system that unites EQUIA Forte Fil, which is a high strength glass hybrid restorative with EQUIA Forte Coat, a wear-resistant, self-adhesive, light-cured resin coating. Due to its new glass hybrid technology, improved acid and wear resistance, and flexural strength, the manufacturer claims that Equia extends the recommended indications to include stress-bearing Class II restorations.⁶

The clinical performance of these materials regarding functional, esthetic, and biological properties is yet to be evaluated. Controlled randomized clinical trials based on widely adopted evaluation systems are crucial for effective evidence-based dental knowledge and restorative practice.⁷ The FDI clinical criteria introduced in 2007 and further modified in 2008 provide detailed evaluation criteria and better differentiation between different types of failure and incorporate objective assessment tools and a clear scoring system.⁸

Thus, this randomized clinical trial aimed to evaluate the clinical performance of a bioactive restorative material ACTIVA BioACTIVE RESTORATIVE vs a glass hybrid restorative material EQUIA Forte Fil in posterior restorations of high-risk caries patients over a period of one year. The null hypothesis was that there will be no difference in the clinical performance of Activa and Equia in high-risk caries patients after one year.

MATERIALS AND METHODS

Materials used in the current study are listed in Table 1.

The protocol of the current study was registered on www.clinicaltrials.gov/database with unique identification number NCT03608306. All procedures done involving human candidates were in fulfillment of the ethical standards of the Research Ethics Committee of Faculty of Dentistry, Cairo University (CREC), (Ref. 18/09/24).

Sample size calculation was done using PS: Power and Sample Size Calculation Software Version 3.1.2 (Vanderbilt University, Nashville, Tennessee, USA). Based on an overall clinical performance score of 56%, 21 restorations were needed in each group to test the null hypothesis with a power of 0.8. By increasing this to 25 per group to compensate for attrition, a statistical significance of p %3C; 0.05 can be attained.

RESULTS

Assessment of 25 restorations in each group was to be done at the baseline, 6, and 12 months. After 6 months, each group had 2 participants drop out, representing 8%. Complete loss of one restoration occurred in one patient of the Activa group at the 6 months evaluation period. After 12 months, 22 (n = 22) restorations in the Activa group and 23 (n = 23) restorations in the Equia group could be evaluated.

The survival percentage for both groups was 98% (86–100 95% CI) after 6 and 12 months. There was no statistically significant difference between the two groups p < 0.05 (Table 2). While for the secondary outcome, at baseline no difference between the tested groups was observed for all esthetic parameters except in color match, which was significantly better for the Activa group (p < 0.05). The same was observed after 6 and 12 months. Activa also scored better in esthetic anatomic form at the 6 and 12 months observation periods (p < 0.05) (Table 3). Regarding functional properties, at baseline, there was no difference between the tested groups with respect to all functional parameters (p %3E; 0.05); however, after 6 and 12 months, Activa scored significantly better for occlusal contour and wear p < 0.001 (Table 4). Regarding, overall primary and secondary outcome result scores, at baseline, no difference between the tested groups was found for all parameters (p > 0.05), except in overall esthetics, which showed a significantly better score for Activa (p < 0.001). At 6 and 12 months, insignificant difference between the tested groups was found for overall biological parameters (p > 0.05). While overall esthetic and functional parameters showed significantly better scores for Activa compared to Equia group.

DISCUSSION

For treatment of cavities in stress-bearing areas, resin composite may be considered the gold standard for treatment in general. However, plaque studies evaluating the level of cariogenic bacteria showed significant lower levels of caries-associated microorganisms related to glass ionomers compared to both resin composite and amalgam restorations.¹²

Glass ionomers are indicated in high-risk caries patients as they inhibit cariogenic bacteria that cause demineralization at the tooth-restoration interface. They also provide good sealing to cavity walls, while in addition providing continuous fluoride ion release and uptake by enamel.¹³ However, glass ionomers are susceptible to dissolution during setting, have reduced wear resistance and poor fracture strengths, long setting times, and undesirable esthetics.¹⁴

Hybrid materials uniting the advantages of glass-ionomer and composites were evolved to overcome these problems, resulting in resin-modified glass ionomer cements (RMGIs), compomers (polyacid-modified composites), Giomers, and recently bioactive resin composites.¹⁵

Recently, in 2013, ACTIVA BioACTIVE RESTORATIVE was launched. Referred to by some¹⁶ as a bioactive composite and considered by others an RMGI.^3,17 It is composed of an ionic resin matrix and a shock-absorbing resin component. Bioactive fillers mimic the physical and chemical properties of teeth. It releases and recharges with Ca, phosphates, and F ions and is esthetically pleasing. Another advantage is a lack of Bis-GMA and BPA derivatives.

Thus, according to Pameijer et al.,3 Activa has the strength, esthetics and physical properties of composites and offers the best of RMGIs. It responds to pH cycles and by releasing Ca, phosphates, and F-ions the formation of mineralized hard tissue is stimulated resulting in a phosphate apatite layer that seals the interface. It has been reported that the biomineralization is at the same level as MTA, Biodentine, and TheraCal LC.¹⁸

For comparison, EQUIA Forte Fil was selected based on properties such as the release of fluoride ions, antimicrobial effect, and the ability to chemically bond to the tooth, thus minimizing microleakage and recurrent caries according to Croll et al.¹⁹ Activa and Equia are both injectable materials with excellent handling characteristics.

The American Dental Association Caries Risk Assessment >6 model was used in this study for the purpose of caries risk assessment and to guide treatment planning. In contrast to a study by Van Dijken et al.,¹⁷ selective enamel etching was performed, and a dentin-bonding agent used prior to restoring the tooth with Activa according to the manufacturer’s instructions.

The Activa restorations were finished with EQUIA Forte Coat to enhance the mechanical properties of the restorations.¹⁸ The coating increases the strength of the glass ionomer and increases its abrasion resistance.²⁰

Assessment of the restorations was performed at baseline, 6 months, and after 1 year. Although long-term follow-up is essential to evaluate the clinical performance of restorative materials, short-term clinical data can give important pieces of information.²¹

The clinical success of restorations depends on many elements, such as caries risk, quality of the restorative material, the size and site of the restoration, parafunctional habits, and operator skills.²² ABR and EFF demonstrated similar successful clinical performance when posterior permanent teeth in high caries risk patients were restored with a 98% survival after 1 year. This is in agreement with Bhadra et al.²³ The success was attributed to the ionic resin component of Activa that has phosphate acid groups with antimicrobial action, which enhances the interactivity between the resin and the reactive glass fillers, thus enhancing the interaction with tooth structure. The hydrogen ions separate from the phosphate groups due to an ionization process in the presence of water and are replaced by calcium in the tooth. This ionic interaction unites the restoration and the tooth, fills microgaps, minimizes sensitivity, and protects against secondary caries forming a strong resin apatite complex.

The clinical success of Equia has been reported by several authors^12,22,24,25 and our data are in agreement with these findings. Only Balkaya et al.²¹ reported a high failure rate for Activa in Cl II restorations and recommended its use to be carefully considered.

The biological properties as primary outcome and recurrence of decay scored 100% success with a score of 1 for both restorative materials after 1 year. This could be due to cavity design, with no weak cusps or undermined enamel,^26,27 biocompatibility of the materials,²⁸ and the superior sealing of Activa.²⁹ This contradicts reports that the weak antibacterial properties of Activa are not effective in preventing caries.^30,31

Regarding postoperative hypersensitivity and tooth vitality, periodontal response, adjacent mucosa and oral and general health, 95.7% of the restorations had excellent scores after 1 year with no statistically significant difference between both materials p %3E; 0.05. In each group one restoration failed, Activa due to lack of retention and Equia due to fracture.

With respect to functional properties, Activa after 6 months had statistically significantly better scores for occlusal contour and wear (p < 0.005). This is in agreement with Garcia-Godoy and Morrow,³² and Bansal et al.⁴ Loss of anatomic form of Equia restorations may occur following abrasion of the coating.²⁴

According to the American Dental Association, a restorative material intended for use in posterior teeth needs to have a retention rate of at least 90% after 18 months of clinical service to be accepted as a definitive restorative material.⁸ The current study lasted 12 months with both groups scoring a retention rate >90%. This suggests that both materials performed well up to 12 months. Each group had a failure, ABR with the loss of one restoration and EFF with 2 chipped restorations. These failures may be attributed to excessive occlusal loads or less than ideal cavity preparations.³³

The Equia Forte restoration with an unsatisfactory score was a compound class II restoration. Due to the difficulty applying the protective resin coating interproximal this surface may be prone to early moisture exposure resulting in loss of material. Glass ionomers can chemically adhere to metals, and microcracks may be induced by the force applied during removing the matrix in the glass ionomer cement. These microcracks make the restoration more prone to chemical attacks.²¹

With respect to esthetic properties, our results are in agreement with Balkaya et al.²¹ At baseline, 6, and 12 months, Activa had a significantly better score (100% clinically excellent) compared to Equia. Of interest is to note that after 6 months, the color match of Equia improved from score 3 (sufficient) to score 2 (good). These findings are in agreement with Diem et al.³⁴ who also observed an improvement over a 3-year period (25% good at baseline, increasing to 80% good at 3 years), as well as better translucency over time with the cement maturation. However, improvement of color is not universally shared as other authors²¹ reported no improvement of Equia.

Our findings agree with Bhadra et al.²³ who stated that Activa imitates the physical and chemical properties of natural teeth by uniting the good mechanical properties and esthetics of composites with all the advantages of glass ionomers.

The null hypothesis was accepted. There was no difference in the clinical performance of ACTIVA^™ BioACTIVE-RESTORATIVE and EQUIA Forte in high caries risk patients at the end of 1 year. However, ACTIVA^™ BioACTIVE RESTORATIVE^™ exhibited better clinical performance than EQUIA Forte in particular for occlusal contour and wear, color match, and esthetic anatomic form.

The main limitation of our study was being a short-term clinical study; however, patients will continue to be evaluated in the future. To encourage compliance, participants received comprehensive dental treatment and are scheduled for periodic follow-ups.

CONCLUSION

At the end of 1 year, both ACTIVA^™ BioACTIVE-RESTORATIVE^™ and EQUIA Forte showed similar and successful clinical performance while restoring posterior permanent teeth in high-risk caries patients. The use of EQUIA Forte as a semi-permanent restorative material in stress bearing cavities rather than a permanent material might be more appropriate. Regarding restoring posterior teeth in the esthetic zone (upper premolars), ACTIVA^™ BioACTIVE RESTORATIVE^™ exhibited superior esthetics.

DISCLOSURE STATEMENT

Drs. Essa, Akah, Yousry, Hassanein and Hamza declared no conflict of interest. Dr Pameijer is a consultant for Pulpdent Corporation. Dr Mai Mahmoud Yousry passed away during the preparation of this manuscript.

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