Testing the Tools: The Best of Bioactive Materials

  • by AGD Staff
  • May 22, 2023
Interest is high in bioactive materials because of the role they play in regenerating tissue. AGD Impact Testing the Tools columnist Ross Isbell, DMD, MAGD, of Isbell Dental in Gadsden, Alabama, frequently reviews bioactive materials he tests in his own practice for a variety of applications. For this week’s issue, we highlight a few of his recent reviews.

A Long-Lasting Antimicrobial Restorative Solution 

Dental Restoratives

Infinix (1)I would argue that the introduction of positive bioactivity and disruption of the decay process is the most important pursuit of the dental industry. From fluoridated water to filling materials that actively introduce good ions, there have been great gains in materials, but nothing like the Infinix™ line from Nobio. Products like antibacterial drugs and mouthrinses all have a particular lifetime of action and therefore can lead to resistance or reinfection. Since Infinix is a new product, there aren’t long-term studies on the success of its quaternary ammonium silicate (QASi) filler particles at reducing decay. However, the product’s claim of “an antibacterial cavity-cleansing effect” suggests promising data showing a dramatic reduction in bacterial presence that isn’t reduced over the product’s lifetime. This has been demonstrated in situations both from contacting the surface of restorations as well as from saliva that has been in contact with the restorations over a six-month timeframe. Unlike other bioactive materials that promote the uptake and release of ions like silver and fluoride, the QASi particles are embedded in the materials and don’t leech into the oral environment, and there is also no material release. Instead, they cause bacterial cell wall lysis upon contact. With nano-hybrid filler particles ranging in size from 40 nanometers to 3 micrometers, the consistency of the flowable and standard composites is similar to comparable products with easy handling and ability to sculpt. The Infinix family of products also includes a two-step adhesive with a self-etching primer and a light-curing bonding agent that shares the antimicrobial QASi effects and is therefore recommended to be used instead of your typical bonding agent. Currently, they are limited to only A2 and A3, but I don’t find that a limitation because I’m primarily using it in high-caries-risk patients, and A2 fits most people. This is not a bulk fill material with only a 2-millimeter depth of cure — it is strong enough to stand up in all normal composite restoration situations. While it’s too early to know if this material functions as promised, antimicrobial particle activity has the potential to reduce or eliminate secondary caries, and, in my opinion, that’s a chance worth taking.

A Versatile New SDF Option in the Preventive Market 

Riva Star Aqua 
SDI Ltd. 

Riva Star AquaSilver diamine fluoride (SDF) has become one of the most important products in cariogenic biofilm inhibition and caries prevention treatments available to the dental team. There are several options, but I have found SDI’s Riva Star system to work best for me. This two-step system introduces a new player to the SDF game, potassium iodide (KI), which in itself does not have any important effects on teeth but does have a critical effect on SDF. When KI interacts with 38% SDF, it forms a creamy white precipitate of silver iodide that functions the same as standard SDF when binding to tooth structure and occluding dentinal tubules before it turns clear and is easily washed away. Hardness measurements have determined that Riva Star treatment is more effective than standard sodium fluoride varnish treatments. By combining with the free-floating silver ions, the KI turns the typically dark staining of SDF into a white color that can even mask decay after it binds. The biggest downside to the original Riva Star formula is that the SDF solution is suspended in ammonia and has a slightly unpleasant smell and taste and can sometimes cause gingival irritation. SDI’s new Aqua product uses a water-based suspension fluid instead and yields the same results but with a better taste and no gingival irritation. In my office, we primarily use Riva Star for high-caries-risk patients or patients who have high caries scores. However, since the silver iodide precipitate does such a great job of occluding dentinal tubules, it also works as a localized desensitizer. If you use the original Riva Star, SDI recommends applying a gingival barrier to prevent irritation, but that isn’t necessary with Aqua. It is best to apply the SDF to as clean a tooth surface as you can, so you should attempt to minimize biofilm by polishing with a prophy cup or at least some gauze before painting the affected sites. When applying Riva Star, be careful handling the bottle containing the SDF because, in the same way that SDF can stain teeth, it will also stain your countertops. This is an easy way to stop decay without the need for anesthesia and can help save teeth before they decay — or at least until you have a chance to restore them.

Flowable and Dense Makes a Winner

Ceramir® Protect LC

Ceramir Protect LCCeramir® Protect LC is a newer product on the market and is based on the chemistry involved with the company’s successful bioceramic cement. Unlike the cement, the Ceramir Protect LC does not need to be triturated to be activated and is supplied in a simple-to-use single-barrel tube. After cavity preparation, place the material directly into the area that you suspect is in closest proximity to the pulp chamber, and then light cure. This liner has a creamy consistency and flows easily but has enough density to hold onto whatever wall you place it on. Indicated for direct and indirect pulp capping, this liner promotes the formation of hydroxyapatite by maintaining a high-alkaline pH and releasing calcium steadily. I have not used it in direct pulp capping situations, but I have used it for indirect capping and have had only good reports from patients with deep excavations regarding minimal postoperative sensitivity. Similar to other composite-type pulpal liners, this material is radiopaque and insoluble and is a bright white color to help differentiate it from the overlaying composite layers in case of future excavation.

A Great Choice for Pediatric Pulpotomies 

TheraCal PT® 

TheraCal PTTheraCal® by Bisco has been a longtime pulpal lining product, but the company continues to improve and expand its offerings. What once was a single product is now a family of products that all have great bioactivity. TheraCal PT (pulp therapy) is a dual-cured material that comes in a small double-barrel syringe. Instead of using IRM® or calcium hydroxide, my preference is to use TheraCal PT for pediatric pulpotomies or direct pulp caps. The proprietary tricalcium silicate filler particles are mixed into a hydrophilic monomer so they work well in the presence of blood, but you should definitely achieve some level of hemostasis prior to application. Setting time is typically around 1.5 minutes when not light-cured. The filler particle composition allows a high release of calcium and creates a high-alkaline pH that, in company studies, measured at 11.5 after seven days. This chemistry promotes formation of hydroxyapatite and secondary and tertiary dentin while inhibiting bacterial activity and infiltration. At this point, I’ve had equivalent results compared with calcium hydroxide and with significantly easier placement.

Ready for Deep Preparations 

Activa™ BioACTIVE Base/Liner and Restorative 

Activa BioActive BaseLiner and RestorativePulpdent® is another longtime producer of bioactive dental materials, and a great example of this is the Activa™ BioACTIVE Base/Liner. Like the TheraCal products, the same basic chemistry has been used to create an array of products for most restorative dentistry needs. The Activa BioACTIVE materials are hydrophilic and reactive to pH changes to allow for greater or lesser release of fluoride, phosphate and calcium ions when needed. The Activa Liner in particular has far less water absorption than glass ionomers, so it will remain adhered and flexurally strong. The Liner and most Activa products are dual-cured, so they will work well with deep preparations and help to create new hydroxyapatite in proximity to the pulp even if the curing light cannot reach them. Even without a bonding agent, the bond strength and minimal marginal leakage make this material a safe choice. The regular Activa restorative gun can be a little bulky, but the liner is in a small, easy-to-use double barrel. In deep situations where I once would have placed a glass ionomer as an interim restoration, I’m now placing Activa Liner and Restorative simultaneously as long-term permanent restorations.

A Flowable for Long-Lasting Restorations 

everX Flow™ 
GC America 

everX FlowThis new flowable composite material from GC is a fantastic way to create strong, lasting restorations with easy dispensation. Reinforced with E-glass and barium glass microfibers, this flowable composite is designed for repairing weakened tooth structures quickly. These fibers are quite effective and alter the direction of force transfer, thereby reducing crack propagation in the material. This creates a very tough material that is resistant to compressive forces and highly fracture-resistant. The filler particle concentration is about 70%, which is possible because the fibers and resin are silanated to allow for better bonding to each other and to surrounding tooth structure. When this product line was first introduced, the microfiber length was significantly greater, but it created issues with manipulation and handling. To address this issue, GC made the microfibers much smaller and thinner — approximately 700 nanometers. Most nanohybrid composites have filler particles that are about 1 micrometer and no microfibers, so it definitely still has a chunky feel and appearance. The resin matrix is still creamy, so, while the handling is not like a normal flowable, it is also not cumbersome and still does an excellent job of adapting to uneven surfaces. The density and viscosity are also helpful because they allow for placement on walls with minimal slumping, even when gravity is against you. This material is available in a more transparent bulk shade that can be cured up to 5.5-millimeter depths or a dentin shade that can be cured in 2-mm depths. I prefer the dentin shade because I usually layer flowables anyway to minimize C-factor forces. This material has made its way into my armamentarium for use as a core buildup material primarily, but it is also becoming one of my main materials for temporary coverage of broken cusps or fractured teeth while I wait for presentation of symptoms on trauma teeth or to allow for strength until we have time in the schedule to do an indirect restoration. When I first placed it, I fully expected the material to appear splotchy or inconsistent after curing. However, if polished appropriately, everything looks pretty average and smooth. I highly recommend this material as a quick strong fix for almost any reparative situation.

A Good Powder That’s a Little Hard to Mix 

MTA Angelus® 

MAT AngelusMTA Angelus® powder is a successful example of a mineral trioxide aggregate (MTA) material and is indicated for use in pulp capping, pulpotomies, periapical surgeries and root perforations. Due to the hydrophilic nature of the material and its ability for calcium release, it is very biocompatible and useful in situations involving wetness or blood. My primary complaint is that the granule size of the powder is too large, which makes for difficult mixing if you are aiming to create a putty. However, since MTA Angelus is activated by water, the distilled water that accompanies the powder really only needs to be used to create a more easily transported powder, or it can be mixed as a slurry and dried after placement. The MTA Angelus powder has a setting time of 10–15 minutes, so sometimes it can be difficult to wait long enough for that to harden and close, especially in a situation with uncontrolled bleeding. Since my primary use for MTA Angelus is pediatric pulpotomies and in perforation situations, I typically don’t wait for a full set. Instead, I dry the site with a cotton ball or something similar, place the MTA Angelus, compact and dry again with a cotton ball, then place a light-cured liner material to hold it in place. This allows for some semblance of isolation, and then I continue with either obturation or restoration. The amount of MTA included in one vial will last five to 10 uses if you are conservative, and it is nice that, since it is all contained in a single vial, you can choose the amount you need for the case. While this product does exactly what it sets out to do, I think the handling and delivery is a little difficult.

Ross Isbell, DMD, MBA, currently practices in Gadsden, Alabama, with his father, Gordon Isbell, DMD, MAGD. He attended the University of Alabama at Birmingham (UAB) School of Dentistry and completed a general practice residency at UAB Hospital. Isbell has confirmed to AGD that he has not received any remuneration from the manufacturers of the products reviewed or their affiliates for the past three years. All reviews are the opinions of the author and are not shared or endorsed by AGD Impact or AGD. To comment on this article, email impact@agd.org.